Edema and Related Medical Conditions

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Saturday, December 31, 2005

A Case of Negative Pressure Pulmonary Edema After Breast Implant Surgery

Bob Langenderfer, MEd, RRT-NPS School of Nursing and Health Professions Northern Kentucky University Highland Heights Kentucky USA


Bob Langenderfer: A Case of Negative Pressure Pulmonary Edema After Breast Implant Surgery. The Internet Journal of Pulmonary Medicine. 2005. Volume 5 Number 2.


This case report concerns a 50 year old woman with no prior history of lung disease who exhibited respiratory distress, dyspnea and low oxygen saturations in the recovery room following breast implant surgery. The diagnosis of negative pressure pulmonary edema was made based on immediate history, radiographic exams, and testing that ruled out myocardial infarction and pulmonary embolus. High resolution CT scans revealed multiple non-calcified pulmonary nodules along with moderate-to-severe emphysema from a concealed smoking history.


Negative pressure pulmonary edema (NPPE) is an uncommon but recognized complication of upper airway obstruction. It was first described in children in 1973 ( 1 ). This form of non-cardiogenic pulmonary edema occurs when the patient struggles to inhale against a partially or completely occluded upper airway. In a vigorous adult the inspiratory muscles can generate a negative intrapleural pressure in the range of -50 to -100 cm H2O ( 2 ). The high negative pressure gradient causes fluid to extravasate from the pulmonary capillaries into the interstitial and alveolar spaces ( 3 ). This fluid leak represents non-cardiogenic pulmonary edema, and it may result in immediate or delayed hypoxemia. Even after an upper airway obstruction is alleviated, pulmonary edema can develop immediately or up to six hours later ( 4 ). Upper airway compromise may be due to occlusion of an artificial airway, as when a patient bites down on an endotracheal tube. Or it may come from internal or external obstruction of the natural upper airway, as might happen in epiglottitis or strangulation.

In the case presented below, the radiographic exam was complicated by the recent placement of bilateral breast implants. An under-reported smoking history and unrecognized moderate to severe emphysema were contributing factors.

Case Report

A 50 year old woman status post bilateral breast implant surgery exhibited dyspnea, wheezing, chest pressure, and low oxygen saturations after extubation in the post-anesthesia recovery room. Before extubation she was noted to be in respiratory distress with severe retractions.

A pulmonary consult several hours later described her as pleasant, cooperative, alert and oriented, and speaking in full sentences with only mild dyspnea and some chest pressure. Physical exam at that time revealed clear lungs without wheeze or crackles and an SpO2 of 89% on 2 L/min oxygen by nasal cannula. Cardiac exam noted regular rate and rhythm without chest pain or palpitations. The patient had a history of rheumatoid arthritis treated with methotrexate and gold salts, but no history of pulmonary disease, hemoptysis or pleurisy. Family history was positive for coronary artery disease in both mother and father. Before surgery she had informed the anesthesiologist that she smoked one pack of cigarettes per week, but after the episode of hypoxemia she admitted to smoking more than a pack per day.

The differential diagnosis included reaction to anesthesia, excessive IV fluids, myocardial infarction, pulmonary emboli, and negative pressure pulmonary edema.

A-P portable chest X-ray (Figure 1, chest X-ray of 6/26) revealed bilateral diffuse perihilar infiltrates and right lower lobe atelectasis, but the presence of breast implants complicated the radiographic analysis of both lower lung fields. High resolution chest CT scans with contrast were used to rule out pulmonary emboli. Over a hundred sequential scans revealed no evidence of pulmonary emboli or pneumothorax, but did show pulmonary edema superimposed on moderate-to-marked emphysema with multiple non-calcified small pulmonary nodules (Figure 3, Chest CT #21, and Figure 4, chest CT #31). Subcutaneous emphysema and bilateral breast prostheses in the soft tissue of the anterior chest were consistent with the surgical history.

Serial troponin and creatinine phosphokinase levels along with echocardiography were used to rule out MI. Three successive troponin levels were all less than .35, and CK levels of 432, 497 and 716 reflected the surgical history. Echocardiography showed atria and ventricles normal in size and function, along with normal tricuspid, aortic and mitral valves.
Treatment was successful with oxygen therapy and diuresis. Figure 2, (chest X-ray of 6/27) shows almost complete resolution of the right and left perihilar infiltrates. The patient was discharged on the second postoperative day. Oximetry at rest and during ambulation three weeks later showed a normal saturation of 98% at rest, but during ambulation the SpO2 fell to 85%, reflecting the severity of the emphysema along with the side effects of treatment for rheumatoid arthritis.

The multiple pulmonary nodules seen on Chest X-ray and CT scan were most likely due to the gold and methotrexate used to treat her rheumatoid arthritis.

In this case the patient's lack of honesty before surgery with the anesthesiologist regarding the extent of her smoking contributed to her abrupt deterioration in the post-operative recovery room. Her change in condition was sudden and severe enough to cause significant concern between her surgeon and the anesthesiologist. The discovery of “moderate to severe emphysema” on the chest CT scan along with her admission of smoking more than a pack per day clarified the differential diagnosis


NPPE is an uncommon problem, but it is common and serious enough to warrant quick recognition and effective treatment. NPPE has been estimated to occur in 11% of patients with clinically significant upper airway obstruction requiring treatment ( 5 ). In adults about 50% of NPPE occurrences are due to post-operative laryngospasm ( 6 ). Young physically fit athletes are at risk after surgery because they have the respiratory muscle power required to generate highly negative intrapleural pressures ( 7 ). Risk factors for NPPE include airway lesions, upper airway surgery, obesity and obstructive sleep apnea. Besides post-extubation laryngospasm, reported causes include foreign bodies, hanging, strangulation, croup, epiglottitis, obstructive sleep apnea, and artificial airway obstruction ( 3 ).

Several pathways for the development of NPPE have been proposed, but the exact mechanism has not been determined. In the usual explanation, NPPE begins with a significant upper airway obstruction. Strong inspiratory efforts to overcome the obstruction generate highly negative intrapleural and alveolar pressures, and the high pressure gradient cause fluid to move out of the pulmonary capillaries and into the interstitial and alveolar spaces ( 3 ).

Another explanation for NPPE holds that the highly negative intrathoracic pressures cause an increase in systemic venous return to the heart but a decrease in cardiac output, since pulmonary venous drainage to the left atrium is decreased. Pulmonary capillary pressures increase while alveolar pressures plunge, and alveolar cell junctions are disrupted. Fluid moves rapidly into interstitial and alveolar spaces, and the pulmonary edema fluid remains even after the airway obstruction is relieved ( 4 ). Both of these pathways along with other mechanisms contribute to the development of NPPE.

In clinical presentation, initial findings usually include decreased oxygen saturation, with pink frothy sputum and chest X-ray abnormalities ( 2 ). Manifestations of the acute airway obstruction include stridor, suprasternal and supraclavicular retractions, urgent use of accessory muscles of inspiration, and panic in the facial expression. As NPPE develops, auscultation usually reveals crackles and occasionally wheezes. Pulmonary edema causes both impaired diffusion of oxygen and ventilation/perfusion mismatching, leading to sudden and possibly severe hypoxemia. The typical chest X-ray will show diffuse interstitial and alveolar infiltrates ( 7 ).

The differential diagnosis would include acute respiratory distress syndrome, fluid overload, cardiac abnormalities, pulmonary embolism, and NPPE.

The first treatment priority is relief of the airway obstruction and correction of hypoxemia. The next step is to address the pulmonary edema with a diuretic unless the patient is hypovolemic. Effective airway management and immediate treatment with oxygen and diuretics is sufficient in most cases of NPPE. Persistent airway obstruction may necessitate an artificial airway, and acute respiratory failure would require artificial ventilation with oxygen and appropriate levels of PEEP. If the airway obstruction is due to the patient biting down on the endotracheal tube, a dose of succinylcholine (0.1-0.2 mg/kg) may be needed to relax the jaw muscles ( 7 ).


Bob Langenderfer MEd, RRT-NPS, Respiratory Care Program, School of Nursing and Health Professions, Northern Kentucky University, Nunn Drive HC-225C, Highland Heights, KY 41099. Email: langenderfer@NKU.edu


1. Capitanio MA, Kirkpatrick JA. Obstruction of the upper airway in children as reflected on the chest radiograph. Radiology 1973; 107:159-161.
2. Lathan RS, Silverman ME, Thomas BL, Waters WC. Postoperative pulmonary edema. South Med J. 1999; 92(3):313-315.
3. Butterell H, Riley RH. Life-threatening pulmonary oedema secondary to tracheal compression. Anaesth Intensive Care 2002;30(6)804-806.
4. Tarrac SE. Negative pressure pulmonary edema - a postanesthesia emergency. J Perianesth Nurs. 2003;18(5):317-323.
5. Melinick BM. Postlaryngospasm pulmonary edema in adults. Anesthesiology 1984; 60:516-517.
6. Goli AK, Goli SA, Byrd RP, Roy TM. Spontaneous negative pressure changes: an unusual cause of noncardiogenic pulmonary edema. J Ky Med Assoc 2003;101(8): 317-320.
7. Davidson S, Guinn C, Gacharna D. Diagnosis and treatment of negative pressure pulmonary edema in a pediatric patient: a case report. AANA J 2003; 72(5): 337-338.

The Internet Journal of Pulmonary Medicine*

*Article with Diagnostic and Evaluative Images

Tuesday, December 20, 2005

Neck Edema

Neck swelling

Some neck swelling may be present after an injury to the neck, but the swelling will go away once healing begins.

Common causes of neck swelling include:

Enlarged lymph nodes from an infection, such as a sore throat or from a cancerous tumor.

An enlarged thyroid gland from thyroid hormone changes.

Deep neck
abscesses from a throat or mouth infection.

Cysts near the jaw, such as a thyroglossal duct cyst, or below the earlobe, such as a brachial cleft cyst.

Swollen salivary glands.

Mumps. Swelling of the parotid gland may cause facial and neck swelling.


Monday, December 19, 2005

Edema Glossary

Abdomen: The belly , that part of the body that contains all of the structures between the chest and the pelvis . The abdomen is separated anatomically from the chest by the diaphragm , the powerful muscle spanning the body cavity below the lungs . See the entire definition of Abdomen

Abdominal: Relating to the abdomen, the belly , that part of the body that contains all of the structures between the chest and the pelvis . The abdomen is separated anatomically from the chest by the diaphragm , the powerful muscle spanning the body cavity below the lungs . See the entire definition of Abdominal

Abdominal cavity: The cavity within the abdomen, the space between the abdominal wall and the spine. See the entire definition of Abdominal cavity

Albumin: The main protein in human blood and the key to the regulation of the osmotic pressure of blood. Chemically, albumin is soluble in water, precipitated by acid, and coagulated by heat. See the entire definition of Albumin

Alveoli: The plural of alveolus. The alveoli are tiny air sacs within the lungs where the exchange of oxygen and carbon dioxide takes place.

Analysis: A psychology term for processes used to gain understanding of complex emotional or behavioral issues. See the entire definition of Analysis

Angiotensin: A family of peptides (smaller than proteins) that act as vasoconstrictors to narrow blood vessels.

Antihypertensive: Something that reduces high blood pressure (hypertension).

Artery: A vessel that carries blood high in oxygen content away from the heart to the farthest reaches of the body. Since blood in arteries is usually full of oxygen, the hemoglobin in the red blood cells is oxygenated. The resultant form of hemoglobin (oxyhemoglobin) is what makes arterial blood look bright red. See the entire definition of Artery

Ascites: Abnormal buildup of fluid in the abdomen. Ascites can occur as a result of a number of conditions, including severe liver disease and the presence of malignant cells within the abdomen.

Auricle: 1. The principal projecting part of the ear. Also called the pinna.2. Something ear shaped such as the upper chambers of the heart. Also called the atria.Auricle is not to be confounded with oracle. Neither the pinna nor the atria possess oracular powers.

Balance: A biological system that enables us to know where our bodies are in the environment and to maintain a desired position. Normal balance depends on information from the inner ear, other senses (such as sight and touch) and muscle movement. See the entire definition of Balance

Bicarbonate: In medicine, bicarbonate usually refers to bicarbonate of soda (sodium bicarbonate, baking soda) white powder that is common ingredient in antacids. Also, the bicarbonate level is an indirect measure of the acidity of the blood that is determined when electrolytes are tested. The normal serum range for bicarbonate is 22-30 mmol/L.

Biopsy: The removal of a sample of tissue for purposes of diagnosis. (Many definitions of "biopsy" stipulate that the sample of tissue is removed for examination under a microscope. This may or may not be the case. The diagnosis may be achieved by other means such as by analysis of chromosomes or genes.) See the entire definition of Biopsy

Blood: The familiar red fluid in the body that contains white and red blood cells, platelets, proteins, and other elements. The blood is transported throughout the body by the circulatory system. Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous blood is the means by which carbon dioxide and metabolic by-products are transported to the lungs and kidneys, respectively, for removal from the body.

Blood clot: Blood that has been converted from a liquid to a solid state. Also called a thrombus . See the entire definition of Blood clot

Blood sugar: Blood glucose. See also: High blood sugar; Low blood sugar.

Capillaries: Capillaries are the smallest of blood vessels. They serve to distribute oxygenated blood from arteries to the tissues of the body and to feed deoxygenated blood from the tissues back into the veins. The capillaries are thus a central component in the circulatory system, essentially between the arteries and the veins. When pink areas of skin are compressed, this causes blanching because blood is pressed out of the capillaries. The blood is the fluid in the body that contains, among other elements, the red blood cells (erythrocytes) that carry the oxygen and give the blood its red color.

Cardiac: Having to do with the heart. See the entire definition of Cardiac

Cavities: Holes in the two outer layers of a tooth called the enamel and the dentin. The enamel is the outermost white hard surface and the dentin is the yellow layer just beneath enamel. Both layers serve to protect the inner living tooth tissue called the pulp, where blood vessels and nerves reside. Small cavities may not cause pain, and may be unnoticed by the patient. Larger cavities can collect food, and the inner pulp of the affected tooth can become irritated by bacterial toxins, foods that are cold, hot, sour, or sweet - causing toothache. Also referred to as caries.

Chest: The area of the body located between the neck and the abdomen . The chest contains the lungs , the heart and part of the aorta . The walls of the chest are supported by the dorsal vertebrae , the ribs , and the sternum . See the entire definition of Chest

Chronic: This important term in medicine comes from the Greek chronos, time and means lasting a long time. See the entire definition of Chronic

Circulation: The movement of fluid in a regular or circuitous course. Although the noun "circulation" does not necessarily refer to the circulation of the blood, for all practical purposes today it does. Heart failure is an example of a problem with the circulation.

Cirrhosis: An abnormal liver condition characterized by irreversible scarring of the liver. Alcohol and viral hepatitis B and C are among the many causes of cirrhosis. Cirrhosis can cause yellowing of the skin (jaundice), itching, and fatigue. Diagnosis of cirrhosis can be suggested by physical examination and blood tests, and can be confirmed by liver biopsy in some patients.

Complications of cirrhosis include mental confusion, coma, fluid accumulation (ascites), internal bleeding, and kidney failure. Treatment of cirrhosis is designed to limit any further damage to the liver as well as complications. Liver transplantation is becoming an important option for patients with advanced cirrhosis.

Clinical: 1. Having to do with the examination and treatment of patients. 2. Applicable to patients. A laboratory test may be of clinical value (of use to patients). See the entire definition of Clinical

Compression: 1. The act of pressing together. As in a compression fracture, nerve compression, or spinal cord compression. 2. To shorten in time. In embryology, there may be compression of development with some stages even omitted.

Condition: The term "condition" has a number of biomedical meanings including the following:
An unhealthy state, such as in "this is a progressive condition."
A state of fitness, such as "getting into condition."

Something that is essential to the occurrence of something else; essentially a "precondition."

As a verb: to cause a change in something so that a response that was previously associated with a certain stimulus becomes associated with another stimulus; to condition a person, as in behavioral conditioning.

Diagnosis: 1 The nature of a disease ; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies . 3 The identification of any problem. The diagnosis was a plugged IV. See the entire definition of Diagnosis

Dialysis: The process of cleansing the blood by passing it through a special machine. Dialysis is necessary when the kidneys are not able to filter the blood. Dialysis allows patients with kidney failure a chance to live productive lives. There are two types of dialysis: hemodialysis and peritoneal dialysis. Each type of dialysis has advantages and disadvantages. Patients can often choose the type of long term dialysis that best matches their needs.

Dilate: To stretch or enlarge. It comes from the Latin verb "dilatare" meaning "to enlarge or expand."

Disease: Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs). Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.

Diuretic: Anything that promotes the formation of urine by the kidney. (The word "diuretic" comes from a combination of the Greek "dia-", thoroughly + "ourein", to urinate = to urinate thoroughly). See the entire definition of Diuretic

Dysfunction: Difficult function or abnormal function. See the entire definition of Dysfunction

Edema: The swelling of soft tissues as a result of excess water accumulation. See the entire definition of Edema

Esophagus: The tube that connects the pharynx (throat) with the stomach. The esophagus lies between the trachea (windpipe) and the spine. It passes down the neck, pierces the diaphragm just to the left of the midline, and joins the cardiac (upper) end of the stomach. In an adult, the esophagus is about 25 centimeters (10 inches) long. When a person swallows, the muscular walls of the esophagus contract to push food down into the stomach. Glands in the lining of the esophagus produce mucus, which keeps the passageway moist and facilitates swallowing. Also known as the gullet or swallowing tube. From the Greek oisophagos, from oisein meaning to bear or carry + phagein, to eat.

Feet: The plural of foot, both an anatomic structure and a unit of measure. See the entire definition of Feet

Gallop rhythm: Heart rhythm like the gallop of a horse. See the entire definition of Gallop rhythm

Gynecomastia: Excessive development of the male breasts. Temporary enlargement of the breasts is not unusual or abnormal in boys during adolescence or during recovery from malnutrition. Gynecomastia may be abnormal as, for example, in Klinefelter's syndrome.

Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest. See the entire definition of Heart

Heart disease: Any disorder that affects the heart. Sometimes the term "heart disease" is used narrowly and incorrectly as a synonym for coronary artery disease. Heart disease is synonymous with cardiac disease but not with cardiovascular disease which is any disease of the heart or blood vessels. Among the many types of heart disease, see, for example: Angina; Arrhythmia; Congenital heart disease; Coronary artery disease (CAD); Dilated cardiomyopathy; Heart attack (myocardial infarction); Heart failure; Hypertrophic cardiomyopathy; Mitral regurgitation; Mitral valve prolapse; and Pulmonary stenosis.

Heart failure : Inability of the heart to keep up with the demands on it and, specifically, failure of the heart to pump blood with normal efficiency. When this occurs, the heart is unable to provide adequate blood flow to other organs such as the brain, liver and kidneys. Heart failure may be due to failure of the right or left or both ventricles. The signs and symptoms depend upon which side of the heart is failing. They can include shortness of breath (dyspnea), asthma due to the heart (cardiac asthma), pooling of blood (stasis) in the general body (systemic) circulation or in the liver's (portal) circulation, swelling ( edema ), blueness or duskiness (cyanosis), and enlargement (hypertrophy) of the heart. See the entire definition of Heart failure

Heart muscle: A type of muscle with unique features only found in the heart. The heart muscle, or cardiac muscle, is medically called the myocardium ("myo-" being the prefix denoting muscle).

Hospital: It may seem unnecessary to define a "hospital" since everyone knows the nature of a hospital. A hospital began as a charitable institution for the needy, aged, infirm, or young. See the entire definition of Hospital

Hypertension: High blood pressure , defined as a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 with a diastolic pressure above 90. See the entire definition of Hypertension

Hypoalbuminemia: An abnormally low blood level of albumin. Normally, albumin is the most plentiful protein in human blood and the key to the regulation of its osmotic pressure.

Idiopathic: Of unknown cause. Any disease that is of uncertain or unknown origin may be termed idiopathic. For example, acute idiopathic polyneuritis , diffuse idiopathic skeletal hyperostosis , idiopathic pulmonary fibrosis , idiopathic scoliosis , etc. See the entire definition of Idiopathic

Inflammation: A basic way in which the body reacts to infection , irritation or other injury, the key feature being redness, warmth, swelling and pain . Inflammation is now recognized as a type of nonspecific immune response . See the entire definition of Inflammation

Interstitial: Pertaining to being between things, especially between things that are normally closely spaced. See the entire definition of Interstitial

Kidney: One of a pair of organs located in the right and left side of the abdomen which clear "poisons" from the blood, regulate acid concentration and maintain water balance in the body by excreting urine. The kidneys are part of the urinary tract. The urine then passes through connecting tubes called "ureters" into the bladder. The bladder stores the urine until it is released during urination.
See the entire
definition of Kidney

Leg: In popular usage, the leg extends from the top of the thigh down to the foot. However, in medical terminology, the leg refers to the portion of the lower extremity from the knee to the ankle. See the entire definition of Leg

Liver: An organ in the upper abdomen that aids in digestion and removes waste products and worn-out cells from the blood. The liver is the largest solid organ in the body. The liver weighs about three and a half pounds (1.6 kilograms). It measures about 8 inches (20 cm) horizontally (across) and 6.5 inches (17 cm) vertically (down) and is 4.5 inches (12 cm) thick.
See the entire
definition of Liver

Liver disease: Liver disease refers to any disorder of the liver. The liver is a large organ in the upper right abdomen that aids in digestion and removes waste products from the blood. See the entire definition of Liver disease

Lungs: The lungs are a pair of breathing organs located with the chest which remove carbon dioxide from and bring oxygen to the blood. There is a right and left lung.
Membrane: A very thin layer of tissue that covers a surface.

Menstrual: Pertaining to menstruation (the menses), as in last menstrual period, menstrual cramps, menstrual cycle, and premenstrual syndrome. From the Latin menstrualis, from mensis meaning month.

Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."

Neck: The part of the body joining the head to the shoulders. Also, any narrow or constricted part of a bone or organ that joins its parts as, for example, the neck of the femur bone. See the entire definition of Neck

Nevi: The plural of nevus.

Organ: A relatively independent part of the body that carries out one or more special functions. The organs of the human body include the eye, ear, heart, lungs, and liver.
Paracentesis: The removal of fluid from a body cavity using a needle, trocar, cannula, or other hollow instrument. See the entire
definition of Paracentesis

Peripheral: Situated away from the center, as opposed to centrally located. See the entire definition of Peripheral

Peritoneal: Having to do with the peritoneum.

Pleural: Pertaining to the pleura, the thin covering that protects the lungs. The term "pleural" is pronounced like "plural" (but does not have plural meanings).

Potassium: The major positive ion (cation) found inside of cells. The chemical notation for potassium is K+. See the entire definition of Potassium

Protein: A large molecule composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein. See the entire definition of Protein

Pulmonary: Having to do with the lungs. (The word comes from the Latin pulmo for lung).

Pulmonary edema: Fluid in the lungs.

Reabsorption: Absorbing again. For example, the kidney selectively reabsorbs substances such as glucose , proteins, and sodium which it had already secreted into the renal tubules. These reabsorbed substances return to the blood. See the entire definition of Reabsorption

Rebound: Return of the original symptoms when maneuvers or treatment is discontinued.
Receptor: 1. In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds a specific substance. There are many receptors. There is a receptor for ( insulin ; there is a receptor for low-density lipoproteins ( LDL ); etc. To take an example, the receptor for substance P, a molecule that acts as a messenger for the sensation of pain , is a unique harbor on the cell surface where substance P docks. Without this receptor, substance P cannot dock and cannot deliver its message of pain. Variant forms of nuclear hormone receptors mediate processes such as cholesterol metabolism and fatty acid production. Some hormone receptors are implicated in diseases such as diabetes and certain types of cancer. A receptor called PXR appears to jump-start the body's response to unfamiliar chemicals and may be involved in drug-drug interactions.2. In neurology, a terminal of a sensory nerve that receives and responds to stimuli. See the entire
definition of Receptor

Regimen: With the accent on the first syllable (reg as in Reggie Jackson), a regimen is a plan, a regulated course such as a diet, exercise or treatment, designed to give a good result. A low-salt diet is a regimen.

Renal: Having to do with the kidney. From the Latin renes (the kidneys), which gave the French les reins which mean both the kidneys and the lower back.

Rest: 1. Repose. Relaxation.2. A fragment of embryonic tissue that has been retained after the period of embryonic development. Also called an embryonic rest.

Salt: In medicine, salt usually refers to sodium chloride, table salt, used for seasoning food, for the preservation of meat, etc. Salt is found in the earth and in sea water and is isolated by evaporation and crystallization from sea water and other water impregnated with particles of salt. See the entire definition of Salt

Sense: In biology and medicine, the faculty of sensory reception. The ability to convey specific types of external or internal stimuli to the brain and perceive them. Sensory reception occurs through a process known as transduction in which stimuli are converted into nerve impulses which are relayed to the brain. See the entire definition of Sense

Side effects: Problems that occur when treatment goes beyond the desired effect. Or problems that occur in addition to the desired therapeutic effect. See the entire definition of Side effects

Skin: The skin is the body's outer covering. It protects us against heat and light, injury, and infection. It regulates body temperature and stores water, fat, and vitamin D. Weighing about 6 pounds, the skin is the body's largest organ. It is made up of two main layers; the outer epidermis and the inner dermis.
See the entire
definition of Skin

Sodium: The major positive ion (cation) in fluid outside of cells. The chemical notation for sodium is Na+. When combined with chloride, the resulting substance is table salt. See the entire definition of Sodium

Syndrome: A set of signs and symptoms that tend to occur together and which reflect the presence of a particular disease or an increased chance of developing a particular disease. See the entire definition of Syndrome

Syringe: A device used in medicine to inject fluid into or withdraw fluid from the body. Medical syringes consist of a needle attached to a hollow cylinder that is fitted with a sliding plunger. The downward movement of the plunger injects fluid; upward movement withdraws fluid. See the entire definition of Syringe

Systemic: Affecting the entire body. A systemic disease such as diabetes can affect the whole body. Systemic chemotherapy employs drugs that travel through the bloodstream and reach and affect cells all over the body. See the entire definition of Systemic

Testicles: The testicles (also called testes or gonads) are the male sex glands. They are located behind the penis in a pouch of skin called the scrotum. The testicles produce and store sperm, and they are also the body's main source of male hormones (testosterone). These hormones control the development of the reproductive organs and other male characteristics, such as body and facial hair, low voice, and wide shoulders.

Therapy: The treatment of disease . See the entire definition of Therapy

Thrombophlebitis: Inflammation of a vein that occurs when a blood clot forms.

Thyroid: 1. The thyroid gland. Also, pertaining to the thyroid gland. 2. A preparation of the thyroid gland used to treat hypothyroidism. 3. Shaped like a shield. (The thyroid gland was so-named by Thomas Wharton in 1656 because it was shaped like an ancient Greek shield.)

Tissue: A tissue in medicine is not like a piece of tissue paper. It is a broad term that is applied to any group of cells that perform specific functions. A tissue in medicine need not form a layer. Thus,

The bone marrow is a tissue;
Connective tissue consists of cells that make up fibers in the framework supporting other body tissues; and
Lymphoid tissue is the part of the body's immune system that helps protect it from bacteria and other foreign entities.

Uric acid: A breakdown product of purines that are part of many foods. In gout, there are frequently, but not always, elevated levels of uric acid in the blood (hyperuricemia). However, only a small portion of those with hyperuricemia will develop gout.

Urinary: Having to do with the kidneys, ureters, and bladder. The urinary system represents the functional and anatomic aspects of the kidneys, ureters, and bladder.

Urine: Liquid waste. The urine is a clear, transparent fluid. It normally has an amber color. The average amount of urine excreted in 24 hours is from 40 to 60 ounces (about 1,200 cubic centimeters). Chemically, the urine is mainly an aqueous (watery) solution of salt (sodium chloride) and substances called urea and uric acid. Normally, it contains about 960 parts of water to 40 parts of solid matter. Abnormally, it may contain sugar (in diabetes), albumen (a protein) (as in some forms of kidney disease), bile pigments (as in jaundice), or abnormal quantities of one or another of its normal components.

Vascular: Relating to the blood vessels of the body. The blood vessels of the body, as a group, are referred to as the vascular system. See the entire definition of Vascular

Vein: A blood vessel that carries blood low in oxygen content from the body back to the heart. The deoxygenated form of hemoglobin (deoxyhemoglobin) in venous blood makes it appear dark. Veins are part of the afferent wing of the circulatory system which returns blood to the heart. See the entire definition of Vein

Ventricle: A chamber of an organ. For example, the four connected cavities (hollow spaces) in the central portion of the brain and the lower two chambers of the heart are called ventricles.

Ventricles: 1, The right ventricle and the left ventricle, the lower two chambers of the heart. 2. Two or more of the four connected spaces within the central portion of the brain.

Vessel: A tube in the body that carries fluids: blood vessels or lymph vessels.


Sunday, December 18, 2005

Kidney Disease and Edema

Why does edema occur in patients with kidney disease?

Edema forms in patients with kidney disease primarily for one of two reasons: either a heavy loss of protein in the urine or impaired kidney (renal) function. In the first situation, the patients have normal or fairly normal kidney function. The heavy loss of protein in the urine (over 3.0 grams per day) is termed the nephrotic syndrome and results in a reduction in the concentration of albumin in the blood (hypoalbuminemia). Since albumin helps to maintain blood volume in the blood vessels, a reduction of fluid in the blood vessels occurs. The kidneys then register that there is depletion of blood volume and, therefore, attempt to retain salt. Consequently, fluid moves into the interstitial spaces, thereby causing pitting edema.

The treatment of fluid retention in these patients is to reduce the loss of protein into the urine and to restrict salt in the diet. The loss of protein in the urine may be reduced by the use of ACE inhibitors and angiotensin receptor blockers. Both categories of drugs, which ordinarily are used to lower blood pressure, prompt the kidneys to reduce the loss of protein into the urine. Examples of ACE inhibitors drugs are enalapril (Vasotec), quinapril (Accupril), captopril (Capoten), benazepril (Lotensin), lisinopril (Zestril or Prinivil), and ramapril (Altase). Examples of angiotensin receptor blockers are losartan (Cozaar), valsartin (Diovan), candesartin (Atacand), and irbesartan (Avapro). Certain kidney diseases may contribute to the loss of protein in the urine and the development of edema. A biopsy of the kidney may be needed to make a diagnosis of the type of kidney disease, so that specific treatment, if available, can be given.

In the second situation, patients who have kidney diseases that impair renal function develop edema because of a limitation in the kidneys' ability to excrete sodium into the urine. Thus, patients with kidney failure from whatever cause will develop edema if their intake of sodium exceeds the ability of their kidneys to excrete the sodium. The more advanced the kidney failure, the greater the problem of salt retention is likely to become. The most severe situation is the patient with end-stage kidney failure who requires dialysis therapy. This patient's salt balance is totally regulated by dialysis, which can remove salt during the treatment. Dialysis is a method of cleansing the body of the impurities that accumulate when the kidneys fail. Dialysis is accomplished by circulating the patient's blood over an artificial membrane (hemodialysis) or by using the patient's own abdominal cavity (peritoneal membrane) as the cleansing surface. Individuals whose kidney function declines to less than 5 to 10% of normal may require dialysis.

Medicine Net

Liver Disease and Edema

Why do patients with liver disease develop ascites and edema?

In patients with chronic diseases of the liver, fibrosis (scarring) of the liver often occurs. When the scarring becomes advanced, the condition is called cirrhosis of the liver. Ascites is fluid that accumulates in the abdominal (peritoneal) cavity. It is a complication of cirrhosis and appears as an abdominal bulge. The peritoneum is the inner lining of the abdominal cavity, which also folds over to cover the organs inside the abdomen such as the liver, gallbladder, spleen, pancreas, and intestines. Ascites develops because of a combination of two factors: (1) increased pressure in the vein system that carries blood from the stomach, intestines, and spleen to the liver (portal hypertension); and (2) a low level of the protein albumin in the blood (hypoalbuminemia). Albumin, which is the predominant protein in the blood and which helps maintain blood volume, is reduced in cirrhosis primarily because the damaged liver is not able to produce enough albumin.

Other consequences of portal hypertension include dilated veins in the esophagus (varices), prominent veins on the abdomen, and an enlarged spleen. Each of these conditions is due primarily to the increased pressure and accumulation of blood in the abdominal blood vessels. Other signs of chronic liver disease are spider nevi (distinctive vascular malformations) on the skin, certain characteristic changes in the nails, gynecomastia (enlarged breasts), and shrinkage of the testicles (testicular atrophy). The fluid of ascites can be removed from the abdominal cavity by using a syringe and a long needle. This procedure is called paracentesis. Analysis of the fluid can help differentiate ascites that is caused by cirrhosis from other causes of ascites, such as cancer, tuberculosis, congestive heart failure, and nephrosis. Sometimes, when ascites does not respond to treatment with diuretics, paracentesis can be used to remove large amounts of the ascitic fluid.

Peripheral edema, which is usually seen as pitting edema of the legs and feet, also occurs in cirrhosis. The edema is a consequence of the hypoalbuminemia and activation of the renin-angiotensin- aldosterone hormonal system, which prompt the kidneys to retain salt and water. The presence or absence of edema in patients with cirrhosis and ascites is an important consideration in the treatment of the ascites. In patients with ascites without edema, diuretics must be given with extra caution. The reason for this is that a diuresis (induced increased volume of urine) that is too depleting or rapid in these patients can lead to a low blood volume (hypovolemia), which can possibly be followed by kidney and liver failure. In contrast, when patients who have both edema and ascites undergo diuresis, the edema fluid in the interstitial space serves as somewhat of a buffer against the development of low blood volume. The excess interstitial fluid moves into the blood vessel spaces to rapidly replenish the depleted blood volume.

Medicine Net

Saturday, December 17, 2005

High altitude cerebral edema

Acute mountain sickness
Alternative names Return to top

High altitude cerebral edema; Altitude anoxia; Altitude sickness; Mountain sickness; High altitude pulmonary edema

Return to top

Acute mountain sickness is an illness that can affect mountain climbers, hikers, skiers, or travelers who ascend too rapidly to high altitude (typically above 8,000 feet or 2,400 meters). This is especially for persons who normally reside at or near sea level.

Causes, incidence, and risk factors Return to top

Reduced atmospheric pressure and a lower concentration of oxygen at high altitude are the causes of this illness. It affects the nervous system, lungs, muscles, and heart. Symptoms can range from mild to life-threatening.

In most cases the symptoms are mild, but in severe cases fluid collects in the lungs (pulmonary edema) causing extreme shortness of breath and further decreasing oxygenation. Swelling may also occur in the brain (cerebral edema), causing confusion, coma, and, if untreated, death.
The likelihood and severity of altitude illness is greater with increasing rate of ascent, higher altitude attained, and higher levels of exertion.

Approximately 20% of people will develop mild symptoms at altitudes between 6,300 to 9,700 feet, but pulmonary and cerebral edema are extremely rare at these heights. However, above 14,000 feet, a majority of people will experience at least mild symptoms, while approximately 10% and 1.5%, respectively, of un-acclimatized people staying at this altitude will develop pulmonary or cerebral edema.

Symptoms Return to top

Symptoms generally associated with mild to moderate altitude illness include:
Difficulty sleeping
Loss of appetite
Nausea or vomiting
Dizziness or light-headedness
Rapid pulse (heart rate)
Shortness of breath with exertion

Symptoms generally associated with more severe altitude illness include:

Shortness of breath at rest
Chest tightness or congestion
Bluish discoloration of the skin
Coughing up blood
Inability to walk in a straight line, or to walk at all
Decreased consciousness or withdrawal from social interaction
Gray or pale complexion (cerebral edema)

Signs and tests Return to top

Listening to the chest with a stethoscope (auscultation) reveals crackles in the lung fields in patients with pulmonary edema.
chest X-ray may be performed.

Treatment Return to top

The mainstay of treatment for all forms of altitude illness is to descend to lower altitude as rapidly and safely as possible. Supplemental oxygen should also be administered, if available.
Hospitalization may be required for severe illness.

Acetazolamide (Diamox) may be used to stimulate breathing, speed acclimatization, and diminish the milder symptoms of acute mountain sickness. Do not consume alcoholic beverages while taking Diamox, and drink sufficient fluids since Diamox increases urination.
Pulmonary edema is treated with oxygen, nifedipine (a high-blood pressure medication also effective for this disorder), and in severe cases, mechanical ventilation.

For cerebral edema, administration of the steroid drug dexamethasone (Decadron) may be helpful.

Expectations (prognosis) Return to top

Most cases are mild, and symptoms improve promptly with a return to lower altitude. Severe cases may result in death due to respiratory distress or brain swelling (cerebral edema).
In remote locations, emergency evacuation may not be possible, or treatment may be delayed.

These conditions could adversely affect the outcome.

Complications Return to top

Pulmonary edema
High altitude cerebral edema (brain swelling)

Calling your health care provider Return to top

Call your health care provider if symptoms of acute mountain sickness develop, even if symptoms resolved when returning to a lower altitude.

Call the local emergency number (such as 9-1-1) or seek emergency medical assistance if severe difficulty breathing develops, if consciousness is decreased, if coughing up blood, or if other severe symptoms are present. If unable to contact emergency help, descend immediately, as rapidly as is safely possible.

Prevention Return to top

Education of mountain travelers before ascent is the key to prevention. Basic principles include: gradual ascent, stopping for a day or two of rest for each 2,000 feet (600 meters) above 8,000 feet (2,400 meters); sleeping at a lower altitude when possible; and learning how to recognize early symptoms so you can return to lower altitude before worsening symptoms occur.
Mountaineering parties traveling above 9,840 feet (3,000 meters) should carry an oxygen supply sufficient for several days.

Acetazolamide (Diamox) helps to speed acclimatization and reduce minor symptoms. Therapy should start one day before the ascent and continue one to two days into the excursion. This measure is recommended for those making a rapid ascent to high altitudes.

Those susceptible to anemia (particularly women) should consult a doctor regarding an iron supplement to correct the condition before traveling in high altitudes. Anemic persons have a reduced red blood cell count, and therefore, a lower amount of oxygen carried in the blood.

Drink sufficient fluids, avoid alcohol, and eat regularly. Foods should be relatively high in carbohydrates.

People with underlying cardiac or pulmonary (lung) diseases should avoid high altitudes.

Update Date: 1/29/2004
Updated by: Cherlin Johnson, M.D., Department of Emergency Medicine, University of Southern California, Los Angeles, CA. Review provided by VeriMed Healthcare Network.

Medline Plus


Acute Mountain Sickness (AMS)

AMS is very common at high altitude. At over 3,000 metres (10,000 feet) 75% of people will have mild symptoms. The occurrence of AMS is dependent upon the elevation, the rate of ascent, and individual susceptibility. Many people will experience mild AMS during the acclimatisation process. The symptoms usually start 12 to 24 hours after arrival at altitude and begin to decrease in severity around the third day.

The symptoms of Mild AMS include:

Nausea & Dizziness
Loss of appetite
Shortness of breath
Disturbed sleep
General feeling of malaise


The pleasures of trekking in the world's highest mountain ranges cannot be overstated. Neither can the dangers. Altitude sickness can occur in some people as low as 8,000 feet, but serious symptoms do not usually occur until over 12,000 feet. Even then it is not the height that is important, rather the speed in which you ascended to that altitude.Acute mountain sickness (AMS) is actually more common in fit young men because they are more likely to attempt a rapid ascent by racing up the mountain like some indestructible super hero! As a general rule, it is far safer (and more enjoyable) to avoid altitude sickness by planning a sensible itinerary that allows for gradual acclimatisation to altitude as you ascend, (you can race back down as fast as you like!).

2,500 to 4,000 metres
8,000 to 13,000 feet
Very High
4,000 to 5,500 metres
13,000 to 18,000 feet
Extremely High
over 5,500metres
over 18,000feet

What is High Altitude?

It is difficult to determine who may be affected by altitude sickness since there are no specific factors such as age, sex, or physical condition that correlate with susceptibility. Some people get it and some people don't because some people are more susceptible than others.Most people can ascend to 2,500 metres (8,000 feet) with little or no effect. If you have been at that altitude before with no problem, you can probably return to that altitude without problems as long as you are properly acclimatised. If you haven't been to high altitude before, you should exercise caution when doing so.

The Causes of Altitude Sickness

The percentage of oxygen in the atmosphere at sea level is about 21% and the barometric pressure is around 760 mmHg. As altitude increases, the percentage remains the same but the number of oxygen molecules per breath is reduced. At 3,600 metres (12,000 feet) the barometric pressure is only about 480 mmHg, so there are roughly 40% fewer oxygen molecules per breath so the body must adjust to having less oxygen.

In addition, high altitude and lower air pressure causes fluid to leak from the capillaries in both the lungs and the brain which can lead to fluid build-up. Continuing on to higher altitude without proper acclimatisation can lead to the potentially serious, even life-threatening altitude sickness.


The main cause of altitude sickness is going too high too quickly. Given enough time, your body will adapt to the decrease in oxygen at a specific altitude. This process is known as acclimatisation and generally takes one to three days at any given altitude, e.g. if you climb to 3,000 metres and spend several days at that altitude, your body will acclimatise to 3,000 metres. If you then climb to 5,000 metres your body has to acclimatise once again.

Several changes take place in the body which enable it to cope with decreased oxygen:

The depth of respiration increases.
The body produces more red blood cells to carry oxygen.
Pressure in pulmonary capillaries is increased, "forcing" blood into parts of the lung which are not normally used when breathing at sea level.
The body produces more of a particular enzyme that causes the release of oxygen from haemoglobin to the body tissues.
Cheyne-Stokes Respirations

Above 3,000 metres (10,000 feet) most people experience a periodic breathing during sleep known as Cheyne-Stokes Respirations. The pattern begins with a few shallow breaths and increases to deep sighing respirations then falls off rapidly even ceasing entirely for a few seconds and then the shallow breaths begin again. During the period when breathing stops the person often becomes restless and may wake with a sudden feeling of suffocation. This can disturb sleeping patterns, exhausting the climber. This type of breathing is not considered abnormal at high altitudes. Acetazolamide is helpful in relieving this periodic breathing.

Acute Mountain Sickness (AMS)

AMS is very common at high altitude. At over 3,000 metres (10,000 feet) 75% of people will have mild symptoms. The occurrence of AMS is dependent upon the elevation, the rate of ascent, and individual susceptibility. Many people will experience mild AMS during the acclimatisation process. The symptoms usually start 12 to 24 hours after arrival at altitude and begin to decrease in severity around the third day.

The symptoms of Mild AMS include:

Nausea & Dizziness
Loss of appetite
Shortness of breath
Disturbed sleep
General feeling of malaise

Symptoms tend to be worse at night and when respiratory drive is decreased. Mild AMS does not interfere with normal activity and symptoms generally subside within two to four days as the body acclimatises. As long as symptoms are mild, and only a nuisance, ascent can continue at a moderate rate. When hiking, it is essential that you communicate any symptoms of illness immediately to others on your trip.

Moderate AMS

The signs and symptoms of Moderate AMS include:

Severe headache that is not relieved by medication
Nausea and vomiting, increasing weakness and fatigue
Shortness of breath
Decreased co-ordination (ataxia).

Normal activity is difficult, although the person may still be able to walk on their own. At this stage, only advanced medications or descent can reverse the problem. Descending only 300 metres (1,000 feet) will result in some improvement, and twenty four hours at the lower altitude will result in a significant improvement. The person should remain at lower altitude until all the symptoms have subsided (up to 3 days). At this point, the person has become acclimatised to that altitude and can begin ascending again.

The best test for moderate AMS is to have the person walk a straight line heel to toe just like a sobriety test. A person with ataxia would be unable to walk a straight line. This is a clear indication that an immediate descent is required. It is important to get the person to descend before the ataxia reaches the point where they cannot walk on their own (which would necessitate a stretcher evacuation).

Severe AMS

Severe AMS results in an increase in the severity of the aforementioned symptoms including: Ÿ Shortness of breath at rest, Ÿ Inability to walk, Ÿ Decreasing mental status, Ÿ Fluid build-up in the lungs, Severe AMS requires immediate descent of around 600 metres (2,000 feet) to a lower altitude.

There are two serious conditions associated with severe altitude sickness; High Altitude Cerebral Oedema (HACO) and High Altitude Pulmonary Oedema (HAPO). Both of these happen less frequently, especially to those who are properly acclimatised. But, when they do occur, it is usually in people going too high too fast or going very high and staying there. In both cases the lack of oxygen results in leakage of fluid through the capillary walls into either the lungs or the brain.

High Altitude Pulmonary Oedema/Edema (HAPO)

HAPO results from fluid build up in the lungs. This fluid prevents effective oxygen exchange. As the condition becomes more severe, the level of oxygen in the bloodstream decreases, which leads to cyanosis, impaired cerebral function, and death.

Symptoms of HAPO include:

Shortness of breath at rest
Tightness in the chest, and a persistent cough bringing up white, watery, or frothy fluid
Marked fatigue and weakness
A feeling of impending suffocation at night
Confusion, and irrational behaviour

Confusion, and irrational behaviour are signs that insufficient oxygen is reaching the brain. One of the methods for testing yourself for HAPO is to check your recovery time after exertion. In cases of HAPO, immediate descent of around 600 metres (2,000 feet) is a necessary life-saving measure. Anyone suffering from HAPO must be evacuated to a medical facility for proper follow-up treatment.

High Altitude Cerebral Oedema/Edema (HACO)

HACO is the result of the swelling of brain tissue from fluid leakage.

Symptoms of HACO include:

Loss of co-ordination
Decreasing levels of consciousness
Loss of memory
Hallucinations & Psychotic behaviour

It generally occurs after a week or more at high altitude. Severe instances can lead to death if not treated quickly. Immediate descent of around 600 metres (2,000 feet) is a necessary lifesaving measure. There are some medications that may be used for treatment in the field, but these require proper training in their use.

Anyone suffering from HACO must be evacuated to a medical facility for follow-up treatment.

Prevention of Altitude Sickness

This involves proper acclimatisation and the possible use of medications.

If possible, don't fly or drive to high altitude. Start below 3,000 metres (10,000 feet) and walk up.

If you do fly or drive, do not overexert yourself or move higher for the first 24 hours.

If you go above 3,000 metres (10,000 feet), only increase your altitude by 300 metres (1,000 feet) per day, and for every 900 metres (3,000 feet) of elevation gained, take a rest day to acclimatise.

Climb high and sleep low! You can climb more than 300 metres (1,000 feet) in a day as long as you come back down and sleep at a lower altitude.

If you begin to show symptoms of moderate altitude sickness, don't go higher until symptoms decrease.

If symptoms increase, go down, down, down!

Keep in mind that different people will acclimatise at different rates. Make sure everyone in your party is properly acclimatised before going any higher.

Stay properly hydrated. Acclimatisation is often accompanied by fluid loss, so you need to drink lots of fluids to remain properly hydrated (at least four to six litres per day). Urine output should be copious and clear to pale yellow.

Take it easy and don't overexert yourself when you first get up to altitude. But, light activity during the day is better than sleeping because respiration decreases during sleep, exacerbating the symptoms.

Avoid tobacco, alcohol and other depressant drugs including, barbiturates, tranquillisers, sleeping pills and opiates such as dihydrocodeine. These further decrease the respiratory drive during sleep resulting in a worsening of symptoms.

Eat a high calorie diet while at altitude.

Remember: Acclimatisation is inhibited by overexertion, dehydration, and alcohol.

Preventative Medications

Acetazolamide (Diamox): This is the most tried and tested drug for altitude sickness prevention and treatment. Unlike dexamethasone (below) this drug does not mask the symptoms but actually treats the problem. It seems to works by increasing the amount of alkali (bicarbonate) excreted in the urine, making the blood more acidic. Acidifying the blood drives the ventilation, which is the cornerstone of acclimatisation.

For prevention, 125 to 250mg twice daily starting one or two days before and continuing for three days once the highest altitude is reached, is effective. Blood concentrations of acetazolamide peak between one to four hours after administration of the tablets.

Studies have shown that prophylactic administration of acetazolamide at a dose of 250mg every eight to twelve hours before and during rapid ascent to altitude results in fewer and/or less severe symptoms (such as headache, nausea, shortness of breath, dizziness, drowsiness, and fatigue) of acute mountain sickness (AMS). Pulmonary function is greater both in subjects with mild AMS and asymptomatic subjects. The treated climbers also had less difficulty in sleeping.

Gradual ascent is always desirable to try to avoid acute mountain sickness but if rapid ascent is undertaken and actazolamide is used, it should be noted that such use does not obviate the need for a prompt descent if severe forms of high altitude sickness occur, i.e. pulmonary oedema or Gradual ascent is desirable to try to avoid acute mountain sickness. If rapid ascent is undertaken and aceazolamide is used, it should be noted that such use does not obviate the need for prompt descent if severe forms of high altitude sickness occur, i.e. pulmonary or cerebral oedema.

Side effects of acetazolamide include: an uncomfortable tingling of the fingers, toes and face carbonated drinks tasting flat; excessive urination; and rarely, blurring of vision.

On most treks, gradual ascent is possible and prophylaxis tends to be discouraged. Certainly if trekkers do develop headache and nausea or the other symptoms of AMS, then treatment with acetazolamide is fine. The treatment dosage is 250 mg twice a day for about three days.

A trial course is recommended before going to a remote location where a severe allergic reaction could prove difficult to treat if it occurred.Dexamethasone (a steroid) is a drug that decreases brain and other swelling reversing the effects of AMS. The dose is typically 4 mg twice a day for a few days starting with the ascent. This prevents most of the symptoms of altitude illness from developing.

WARNING: Dexamethasone is a powerful drug and should be used with caution and only on the advice of a physician and should only be used to aid acclimatisation by sufficiently qualified persons or those with the necessary experience of its use.

For further information go to the Mountain Medicines page.

Treatment of AMS

The only cure for mountain sickness is either acclimatisation or descent.Symptoms of Mild AMS can be treated with pain killers for headache, acetazolamide and dexamethasone. These help to reduce the severity of the symptoms, but remember, reducing the symptoms is not curing the problem and could even exacerbate the problem by masking other symptoms.

Acetazolamide allows you to breathe faster so that you metabolise more oxygen, thereby minimising the symptoms caused by poor oxygenation which is especially helpful at night when the respiratory drive is decreased.

Dexamethasone: This powerful steroid drug can be life saving in people with HACO, and works by decreasing swelling and reducing the pressure in the skull. The dosage is 4 mg three times per day, and obvious improvement usually occurs within about six hours. This drug "buys time" especially at night when it may be problematic to descend. Descent should be carried out the next day. It is unwise to ascend while taking dexamethasone: unlike diamox this drug only masks the symptoms.

Dexamethasone can be highly effective: many people who are lethargic or even in coma will improve significantly after tablets or an injection, and may even be able to descend with assistance. Many pilgrims at the annual festival at Gosainkunda lake in Nepal suffer from HACO following a rapid rate of ascent, and respond remarkably well to dexamethasone. Mountain climbers also sometimes carry this drug to prevent or treat AMS. It needs to be used cautiously, however, because it can cause stomach irritation, euphoria or depression.It may be a good idea to pack this drug for a high altitude trek for emergency usage in the event of HACO In people allergic to sulpha drugs (and therefore unable to take diamox) dexamethasone can also be used for prevention: 4 mg twice a day for about three days may be sufficient.

Other Medicines used for treating Altitude Sickness include:

Ibuprofen which is effective in relieving altitude induced headache. (600mg three times a day).

Nifedipine: This drug is usually used to treat high blood pressure. It rapidly decreases pulmonary artery pressure and also seems able to decrease the narrowing in the pulmonary artery caused by low oxygen levels, thereby improving oxygen transfer. It can therefore be used to treat HAPO, though unfortunately its effectiveness is not anywhere as dramatic that of dexamethasone in HACO. The dosage is 20mg of long acting nifedipine, six to eight hourly.Nifedipine can cause a sudden lowering of blood pressure so the patient has to be warned to get up slowly from a sitting or reclining position. It has also been used in the same dosage to prevent HAPO in people with a past history of this disease.

Frusemide may clear the lungs of water in HAPO and reverse the suppression of urine brought on by altitude. However, Frusemide can also lead to collapse from low volume shock if the victim is already dehydrated. Treatment dosage is 120mg daily.

Breathing · 100% Oxygen also reduces the effects of altitude sickness.

The Gamow Bag

This clever invention has revolutionised field treatment of altitude sickness. The bag is composed of a sealed chamber with a pump. The casualty is placed inside the bag and it is inflated by pumping it full of air effectively increasing the concentration of oxygen and therefore simulating a descent to lower altitude

In as little as 10 minutes the bag can create an "atmosphere" that corresponds to that at 900 to 1,500 metres (3,000 to 5,000 feet) lower. After two hours in the bag, the person's body chemistry will have "reset" to the lower altitude. This acclimatisation lasts for up to 12 hours outside of the bag which should be enough time to get them down to a lower altitude and allow for further acclimatisation.

The bag and pump together weigh about 6.5 kilos (15 pounds) and are now carried on most major high altitude expeditions. Bags can be rented for short term treks or expeditions.

The Travel Doctor