Dr. Hanna Saadeh

Dr. Hanna Saadah - Fever is the elevation of the body temperature above normal. Under ordinary situations the body produces more heat than is required to maintain normal temperatures. However, normal body temperatures are strictly maintained in spite of environmental variations by balancing the heat generated from our metabolism, livers, and muscles against the heat dissipated from our skin and lungs.

The body’s temperature is regulated by our brain’s thermostat, the hypothalamus. When the hypothalamus is reset upward, it triggers the body’s mechanisms that generate and conserve heat such as constriction of skin blood vessels and muscle shivering; when it is reset downward, it triggers mechanisms that dissipate heat such as the opening of the skin blood vessels (flushing), sweating, and rapid breathing.

The average oral temperature is about 36.8 degrees Centigrade or 98.2 degrees Fahrenheit and tends to be lowest at 6 a.m. and highest at 4 p.m. The maximum normal oral temperature is 37.2 °C or 98.9 °F at 6 a.m. and 37.7 °C or 99.9 °F at 4 p.m. Rectal temperatures are about 0.4 °C or 0.7 °F above oral readings. Consequently, temperatures higher than these normal temperatures are considered fevers.

Fever is our body’s reaction to injury, inflammation, certain hormonal storms, and infections—all of which release certain chemicals called toxins and cytokines, which reset the hypothalamus thermostat upwards. When that happens, the skin blood vessels constrict to conserve heat—the muscles shiver and the liver increases it metabolism to generate heat. This process continues until the temperature reaches the higher-set level. The reverse happens when the hypothalamus resets the temperature down, causing the skin to flush and sweat and the lungs to breath faster, thus cooling off the body.

Fever does not help the body’s fight against infection and reducing it does not hinder the body’s defenses. Therefore, fever needs to be treated only if it renders the patient uncomfortable. Otherwise, fever should only be monitored because it gives very valuable information about the progress of disease. Very high fevers, however, may cause seizures, especially in children, and should be promptly treated with medicines and by cooling the body in a water bath.

The treatment of fever rests on the use of antipyretics (Tylenol, Aspirin, and others) all of which reset the hypothalamus thermostat down. Conversely, medications that suppress sweating (anti-cholinergics) or flushing (vasoconstrictors) may interfere with the body’s cooling mechanisms and increase fever.

There are fevers that do not obey the settings of the body’s thermostat. These conditions may occur when heat generation is excessive and heat dissipation is limited by hot external conditions. Examples include laboring or exercising in very hot weather. In such situations the heat generated exceeds the heat dissipated, causing a condition known as hyperthermia, which may lead to heat strokes. Here, using Aspirin or Tylenol will do no good because the body’s thermostat is already set low and lowering it further does not help. Moving to a cooler place and bathing in cool water are the quickest means that reduce this kind of high fever.

Many conditions that directly affect the brain such as hemorrhages and strokes can reset the brain’s thermostat upward, causing high fever. In such cases, it may prove more difficult to reset the thermostat down with medications alone. Moreover, certain medicines can cause very high fevers by directly resetting the brain’s thermostat upward. For example: a) antipsychotics, which block the brain’s hormone dopamine, may cause a very dangerous condition known as the Neuroleptic Malignant Syndrome; b) general anesthetics, in the genetically inclined, may cause an equally dangerous condition called Malignant Hyperthermia; and c) certain antidepressants may cause the deadly Serotonin Syndrome. The treatments for these serious conditions are very complex and require high expertise.

Antibiotics, which are used to treat infections, can themselves cause a high fever known as Antibiotic Fever. The only treatment for this condition is to stop the antibiotics, which causes the fever to defervesce within a few days. Other conditions such as old age, kidney failure, septicemia, and certain medications such as steroids prevent the brain’s thermostat from resetting upward, thus masking fevers and making infections much harder to diagnose.

Although infections do cause fever, not all infections cause fever and not all infections require antibiotics. Viral illnesses such as colds, sore throats, bronchitis etc. will not respond to antibiotics, which can only cause adverse effects. On the other hand, febrile bacterial infections such as pneumonia, strep throat, kidney infections, etc. need prompt antibiotic therapy. Fever is just a warning sign, indicating that something is wrong; finding the cause and deciding whether to treat or not to treat are the real issues.

Edema fluid is formed from the liquid components of blood; it does not contain red or white blood cells because blood cells are too big to leak through the tiny pores in the walls of the small blood vessels (capillaries), which connect our arteries and our veins. There are millions of these capillaries and they regulate the amount of tissue fluid by absorbing it and sending it back up the veins to the heart.

Normal edema results after sitting for prolonged periods of time, as often happens on a long flight. The sitting position bends and constricts our veins at the knees and hips, reducing venous return and tipping the balance in favor of tissue fluid accumulation. Walking corrects this imbalance because muscle action actively pumps blood up the veins whereas lying down enhances venous return by neutralizing gravity. Most edema accumulations are lowest when we get up in the morning and highest after prolonged standing or sitting. It may take several days of lying flat with elevated legs to completely absorb massive edema.

The commonest cause of edema is vein damage, which causes the valves inside our veins to become leaky (insufficient). These valves, which point upward, normally direct the blood-flow against gravity, towards the heart. When these valves become insufficient, some of the returning blood is pulled back by gravity and swelling ensues. Pregnancy, varicose veins, leg trauma, blood clots, knee arthritis, knee or hip operations, and advancing age are common causes of this type of venous insufficiency that is caused by vein damage and valve dysfunction.

Reduced venous flow may also result from increased pressure inside the heart, chest, and abdomen. Conditions such as—liver cirrhosis with increased belly fluid, chronic lung disease, heart failure, heart sac restriction due to scarring or fluid accumulation—all impede venous return and cause swelling. Tumors that compress the chest or abdominal veins and scarring conditions that trap the veins (fibrosis) also lead to swelling.

Low blood proteins diminish the force (osmotic pressure), which holds-in our blood fluids (plasma) and prevents them from leaking out of our blood vessels into the tissues. Conditions such as chronic kidney disease or liver failure, by diminishing our blood proteins below a critical level, increase capillary leakage and cause swelling.

Damage or obstruction of the special channels that help carry protein rich, tissue fluids back to the heart (lymphatic channels) can also result in swelling even when the veins are normal. There are numerous disorders that can cause lymphatic channel dysfunction and the lymph edema that results from such disorders does not respond to diuretics or leg elevation, as does the vein edema. It requires a specific type of repetitive massage therapy, which physically propels the lymph edema fluid out of the feet and upward toward the thighs.

Vein inflammations and clots (thrombophlebitis) can be a silent disease that may not cause swelling or pain. It is important to suspect it because it may send deadly blood clots to the lungs, causing dangerous lung attacks. The causes of leg vain inflammations are numerous but trauma, general surgeries, joint replacements, prolonged bed rest, cancers, autoimmune diseases, clotting disorders, and severe medical illnesses are common predisposing factors.

If leg vein inflammation is not treated promptly with blood thinners, the clots will continue to grow, causing more and more damage to the valves inside our veins. When enough vein valve damage occurs, the swelling that ensues becomes chronic and persists for life, regardless of treatment. This chronic venous insufficiency can be partially improved by wearing knee-high support stockings from the time one leaves one’s bed till the time one returns to it.

Today, the commonest cause of leg swelling is obesity. The excess weight impedes venous return and causes fluid retention via several mechanisms, rendering the swelling resistant to diuretics and physical therapy. Medications may also result in leg swelling either by causing fluid retention or by causing the capillaries to become more leaky or by encouraging blood clots to form inside normal veins.

Leg swelling that does not improve after normal sleep or with diuretics, especially when it affects only one leg, should be promptly investigated. Blood clots to the lungs (pulmonary embolism) should be suspected whenever sudden, unprovoked shortness of breath develops, with or without cough or chest pain.