Marino's Clinical Reports

The purpose of this site is to provide a brief overview of selected medical topics, with emphasis on topics that are either controversial or not readily appreciated by the general public.

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Location: New York, New York, United States

Sunday, February 03, 2008

No Benefit From Antibiotics in Acute Sinusitis

Symptoms of acute sinusitis (i.e., localized pain or purulent nasal discharge) are responsible for about 2% of all patient visits to a doctor's office, and antibiotics are prescribed for as many as 98% of these cases (at a cost of about $2.4 billion annually). In most cases, antibiotics are dispensed without performing tests to confirm the presence of sinusitis, and to determine if the responsible organism is treatable with antibiotics. This practice surely leads to excessive use of antibiotics, but how excessive? The answer to this question is suggested by the following observations (in adults).

The symptoms of acute sinusitis resolve within one or two weeks in most patients, regardless of whether antibiotics are used or not (1,2).

The symptoms of acute sinusitis do not resolve more rapidly when antibiotics are given (3).

These observations indicate that most, if not all, of the antibiotic use in patients with suspected acute sinusitis is excessive and unnecessary.

The prevailing opinion is that antibiotics should NOT be used for routine cases of acute sinusitis. Antibiotics should be reserved only for case where there is evidence of systemic sepsis (e.g., fever) (4), or when the symptoms persist for longer than one week and there is radiographic evidence of acute sinusitis (5).

1. Williams JW Jr, Aguilar C, Cornell J, et al. Antibiotics for acute maxillary sinusitis. Cochrane Reviews 2003; 2:CD000243.

2. Ah-See KW, Evans AS. Sinusitis and its management. BMJ 2007; 334:358-361.

3. Williamson IG, Rumsby K, Benge S, et al. Antibiotics and topical nasal steroid for acute maxillary sinusitis. JAMA 2007; 298:2487-2496.

4. Lindbaek M. Acute sinusitis – to treat or not to treat? JAMA 2007; 298:2543-2544.

5. Ah-See KW. Sinusitis (acute). Clin Evid 2005; 13:646-653.

Tuesday, May 29, 2007

Acetaminophen and Your Liver

Acetaminophen (the main ingredient in Tylenol) is the most widely used pain reliever and fever suppressant in the United States. Each year, Americans consume an estimated 8 billion tablets of acetaminophen (an average of 29 tablets per person). The overwhelming popularity of this drug indicates that the general public views it as being safe and non-toxic. Not so.
Liver Damage
Acetaminophen is known in the medical community for its ability to cause life-threatening liver damage if taken in high doses. Misuse of acetaminophen is responsible for 40 – 50% of all cases of acute liver failure in both the United States and the United Kingdom, and the mortality in these cases is as high as 20%.
Lack of Awareness
The problem with acetaminophen, other than the risk of liver damage, is an apparent lack of awareness of this side effect in the general population. Clinical studies show that as many as 50% of toxic acetaminophen ingestions are not suicide attempts, but rather occur in people who ingest large doses of the drug to relieve pain.
What You Need to Know
The most important measure for preventing acetaminophen-induced liver injury is to limit the daily intake of acetaminophen to a maximum of 4 grams (equivalent to 12 regular-strength tablets, 8 extra-strength tablets, or 4 extended-release tablets). Acetaminophen almost never produces liver damage when the quantity ingested at one time is less than 7 grams, so limiting the total daily dose to 4 grams should eliminate the risk for liver damage. Further restrictions are recommended if alcoholism, HIV infection, and therapy with dilantin (an anticonvulsant) is present. These conditions show an increased susceptibility to acetaminophen-induced liver damage, and the total daily dose of the drug should be less than 4 grams, or a suitable alternative drug should be used.
Look for Acetaminophen in Cold Remedies
It is also important to check for acetaminophen in any drug preparation advertised as a cold remedy or pain reliever. At least 200 drug products contain acetaminophen, and excessive use of these preparations could result in a toxic ingestion. When reviewing the contents of a drug preparation, be aware that acetaminophen is often listed by the abbreviation APAP.
What To Do Following An Overdose
If a toxic ingestion of acetaminophen does occur, immediate medical attention in an emergency room can be life-saving. There is an effective antidote for acetaminophen poisoning, but it must be given within 24 hours of drug ingestion.

What You Should Know About Cholesterol

The association between cholesterol and cardiovascular disease (the leading cause of death in the United States) has created a national obsession with cholesterol, and a multibillion dollar industry for cholesterol-lowering drugs. Unfortunately, the public perception about cholesterol is rooted in as much fancy as fact, and this has created some unsound practices for the control of blood cholesterol. The following information about cholesterol will help to correct this situation, and will help you make well-informed decisions about the cholesterol in your bloodstream.

The Cholesterol Hypothesis
The "cholesterol hypothesis" claims that excess cholesterol in blood will damage the inner lining of blood vessels and promote cardiovascular diseases such as coronary heart disease and stroke. This hypothesis is almost universally accepted by the general public, but is debated by researchers in the field. One of the problems with the cholesterol hypothesis is the inconsistent relationship between blood cholesterol levels and the risk of cardiovascular disease. For example, one of the largest studies of cardiovascular risk factors in the United States (The Framingham Study) showed that elevated blood cholesterol is associated with an increased risk of death from coronary heart disease in people who are under the age of 50, but in people who are over the age of 50, elevated blood cholesterol is associated with a lower risk of death from coronary heart disease.
There are several studies that show no correlation, or a negative correlation, between elevated blood cholesterol and the risk of coronary heart disease. One observation that is particularly interesting comes from a small Italian village named Stocarredo located about a half-mile north of Venice, where residents have excessively high blood levels of cholesterol despite having a much lower incidence of coronary heart disease than the average American. Over 90% of the population of this village shares the same surname, indicating that the tolerance to high cholesterol in these people may be genetic in origin. This observation points to the relative importance of genetic factors over cholesterol (and all other risk factors) in determining the predisposition to coronary heart disease.

Cholesterol in Blood
Cholesterol does not readily dissolve in plasma, and a series of carrier proteins is needed to transport the cholesterol in blood. The cholesterol-protein complexes are called lipoproteins, and there are several lipoproteins identified by their optical density. The lower-density lipoproteins (LDL) are capable of damaging blood vessels and promoting cardiovascular disease, while the higher-density lipoproteins (HDL) have the opposite effect, and can protect blood vessels and prevent cardiovascular disease. As a result of these opposing effects, the risk of cardiovascular disease is determined by the balance between low-density and high-density cholesterol fractions in blood, and not by the total amount of cholesterol in blood. In fact, the total cholesterol level can be misleading because it can be normal despite an elevated LDL-cholesterol ("bad" cholesterol).
Despite the limited value of the total cholesterol level, the routine assay for blood cholesterol (the one used in "screening cholesterol" programs promoted in many health fairs) measures only total cholesterol. This is an unacceptable practice, particularly for health awareness programs that are dedicated to lowering the risk of cardiovascular disease. Remember to ask for a lipoprotein profile to ensure a meaningful evaluation of the cholesterol in your blood.
The most recent recommendations of the National Cholesterol Education Program identifies only LDL-cholesterol as the target of cholesterol-lowering interventions. The desirable level of LDL-cholesterol is determined by the number of other risk factors for cardiovascular disease present in each patient. The other risk factors include age (above 45 years for males or above 55 years for females), smoking, diabetes, hypertension, obesity, HDL-cholesterol less than 40 mg/dL, and a family history of premature coronary heart disease. The target LDL-cholesterol is 160 mg/dL or lower for those with no other risk factors, 130 mg/dL or lower for those with 2 or more additional risk factors, and 100 mg/dL or lower for those with multiple risk factors that include a strong family history of coronary heart disease. (These guidelines are available at

Dietary Restriction
About 85% of the cholesterol in the human body is manufactured by cells in the body (in the liver, intestines, and reproductive organs), while dietary intake contributes only 15% of total body cholesterol. This small contribution of dietary cholesterol means that cholesterol-restricted diets will have little impact on the cholesterol concentration in blood). In fact, when there is a decrease in the dietary intake of cholesterol, the body compensates by increasing the rate of cholesterol production, and this serves to further minimize the effect of cholesterol intake on blood cholesterol levels. Clinical studies have confirmed that dietary restriction of cholesterol has small and inconsistent effects on both total cholesterol and LDL-cholesterol levels in blood. Those "cholesterol free" food labels that are so inviting are more likely to increase sales of the product than lower your blood cholesterol levels.
The dietary factors that will reduce LDL-cholesterol levels include restriction of saturated fatty acids (found in whole milk, cheese, ice cream, and red meat), restriction of trans-fatty acids (present in bread, doughnuts, crackers, cookies, and french fries) and, most importantly, restriction of total calories. Weight reduction through dietary restriction and exercise is the most effective way to reduce LDL-cholesterol levels and avoid the use of cholesterol-lowering drugs.

Cholesterol-Lowering Drugs
When lifestyle modifications (diet, exercise, and weight reduction) do not achieve the desired LDL-cholesterol, then cholesterol-lowering drugs are usually started. The drugs that are most effective are called statins, and they block the metabolic production of cholesterol in the body. These drugs are capable of reducing LDL-cholesterol levels by as much as 50%.
The important question regarding the use of cholesterol-lowering drugs is not their ability to lower LDL-cholesterol levels, but whether this effect is accompanied by a decrease in cardiovascular disease. The evidence from clinical trials shows that these drugs do indeed reduce the incidence of coronary heart disease and stroke, but only in people who have 3 or more risk factors for cardiovascular disease or a strong family history of premature cardiovascular disease. Statins are also not recommended for people who are 70 years of age or older (because the risks from these drugs exceeds the benefits of cholesterol reduction in the elderly).
Are cholesterol-lowering drugs overused? Probably, considering that physicians show a tendency to use these drugs in all adults with an elevated cholesterol or LDL-cholesterol level. The appropriate use of these drugs would limit their use to people with all of the following: 1) an LDL-cholesterol above the target level despite lifestyle modification, 2) three or more risk factors for coronary heart disease, or a strong family history for premature coronary

Saturday, June 25, 2005

Oxygen Enriched Water-Buyer Beware

Although this is not a medical topic, it should be of interest to the legions of bottled water enthusiasts that populate this country. I have noticed in recent months that there are bottled water products that claim to be enriched or supercharged with oxygen. According to one manufacturer, this product will "give you the energy and boost you need during athletic activities". There's even an oxygen-enriched spray that you can squirt in your mouth for that instant energy rush.
Here's the problem: oxygen does not readily dissolve in water. This is the reason we need hemoglobin to carry oxygen in the blood (plasma is 93% water, and not enough oxygen can dissolve in plasma to meet the oxygen needs of aerobic metabolism). Let's see how much oxygen dissolves in water under normal conditions.

How Much Oxygen is in Water?
The volume of a dissolved gas in water can be calculated as the product of the gas pressure and the solubility coefficient for the gas in water. At room temperature, the solubility coefficient for O2 in water is 0.03 mL/L/mmHg. If the partial pressure of oxygen in the atmosphere is 150 mmHg, then one liter of water contains (0.03 x 150 = ) only 5 mLs of oxygen. The whole-body oxygen consumption of an average sized adult at rest is 250 mL/min, which means that for a person who is not active, the oxygen in one liter of water is enough to sustain metabolism for only 1.2 seconds! The situation gets much worse during exercise, where the oxygen consumption can increase 5 to 10-fold.

Is it Possible to Put More Oxygen in Water?
The manufacturers of these products claim they have a patented method for increasing the solubility of oxygen in water, but they give no information on this process, and there is nothing I can find in the scientific literature to support such a claim. Decreasing temperature will increase oxygen solubility in water, but the effect is extremely small. In fact, if there was a method to dissolve more oxygen in water, it could obviate the need for blood transfusions (simply give the oxygen-supercharged water instead). The scientist who discovers such a method would undoubtedly be a candidate for a Nobel Prize !

Thus, the notion of oxygen-enriched water is more fancy than fact, and products that make such claims are best left on the shelves of your grocery or pharmacy.