Hypoxia and Medicine

How does alcohol and smoking contribute to hypoxia, for pilots flying aircraft?

Public Comments

1. I am no doctor, but they reduce the ability of your blood to carry oxygen.
2. Smoking produces carbon monoxide, which sticks to hemoglobin much easier than oxygen. This reduces the hemoglobin available for transporting oxygen to the brain causing Hypemic Hypoxia - which is the inability of blood to carry oxygen. Alcohol inhibits cells from having the ability to effectively use oxygen. This is called Cytotoxic Hypoxia. One ounce of alcohol = 2,000 feet of additional altitude on the body. FYI - There are two other types of hypoxia: 1. Hypoxia - which is an inadequate supply of oxygen (altitude sickness) 2. Stagnant - Inadequate circulation of the blood. This is usually due to heart problems. Hope this answers your question.
3. I am not a pilot or doctor, but was a NAVY enlisted flight crew member for over 16 years. The effects of alcohol are well known, and the navy has a "12 hours bottle (drink) to flight brief minimum time limit. There's also the " it takes one hour for the effects of every 1 ounce of alcohol to wear off" i.e. 5 beers (shots/8 ounce glass of wine) equals being impaired for a minimum of 5 hours from time of last drink. As for the smoking part I used to smoke and smoking impairs blood's ability to carry oxygen. Information (in the mid to late 1990s) published by the U.S. NAVAL Safety Center and Flight Surgeons at the time based on aviation physiology studies carried out in pressure/altitude chambers indicated that the average smoker's blood oxygen levels were the same at sea level as a non smoker's were at 5,000 feet altitude. Navy flight regulations recommended being on oxygen at cabin altitudes above 10,000 feet and required the use of oxygen at altitudes above 13,500 feet, and 100% oxygen above 25,000 feet to prevent and limit the effects of Hypoxia. So if the average smoker's blood is only carring half as much oxygen to the brain as a non smoker's then in theory smokers are more likely to become impaired by the effects of Hypoxia at lower altitudes, possibly suffering the onset of hypoxia at 6,000 feet versus 12,000 feet for a non smoker. However, everybody and case is different. I experieanced explossive decompression above 25,000 feet several times and was able to get on oxygen without passing out. Once I was doing cabin inflight checks and was able to get back to my flight station and a portable oxygen bottle while the other crewmember in the back cabin with me passed out within a couple seconds. I was able to do this by performing the same breathing technique (I forget the name) the BLUE ANGELS flight demonstration team uses. The technique requires sucking in a large amount of air and bearing down hard (as if constipated). The other crew member was also a smoker. Because of requirements to go through refresher physiology every 4 years NAVY flight crew members experience the onset and effects of Hypoxia in a safe, monitored enviroment and learn to recognize the onset of symptoms.
4. This is about education so keep reading, I published this in my 2004 newsletter. Smoking is a habit that is widely accepted in social circles. Therefore one tends to underestimate the effects of smoking. Smoking not only has short-term effects, but has a multitude of long term effects as well. Furthermore, tobacco is considered as a highly addictive drug. The use of tobacco is implicated in development of many diseases including heart disease, circulatory disease, lung disease and numerous cancers. The manner in which smoking contributes to disease includes relative deprivation of oxygen to heart muscle and other tissue, irritation of the lining of the respiratory track and other organs and the constriction of blood vessels. The US Public Health Service has reported that cigarette smokers are 20 times more likely than non-smokers to die from cancer of the esophagus, bladder and pancreas. This is not surprising as a single cigarette contains a considerable amount of carcinogens. (It has been quoted that a single cigarette contains more than 4 000 carcinogens!) Tar is one of the major cancer causing agents. Its primary effect is to cause destruction of the delicate membranes of the respiratory tract and other organs. In pilots smoking reduces tolerance to hypoxia and acceleration, and reduces night vision Smoking and hypoxia There is an assumption that hypoxia is only associated with flight at high altitude. While it is true that there is a progressive decrease of oxygen with increase in altitude, there are many other factors that can lead to hypoxia, including smoking. Combustion of tobacco produces carbon monoxide. Carbon monoxide (CO) binds with hemoglobin in the red blood cells. This reduces the amount of hemoglobin available to bind with oxygen. CO will combine with the hemoglobin about 250 times more readily than oxygen. The hemoglobin involved in this combination is not available to carry oxygen to the tissues, producing a degree of hypoxia and thus reducing individual altitude tolerance. This effect increases with increasing altitude due to progressive decrease of oxygen with increase in altitude. The non-smoker will have carbon monoxide levels of less than ½%. If the smoke of three cigarettes is inhaled at sea level, a blood saturation of 4% CO may result. Heavy smokers may have levels of up to 15%, which leaves this amount of blood unavailable for carrying oxygen. Tar, the residue left from tobacco smoke, also impairs proper oxygenation of the blood, which leads to an additive reduction in tolerance to hypoxia. Although the CAR's allow a pilot to fly below 12 000 feet without oxygen, the smoker may have subtle effects of hypoxia at lower altitudes and the imperceptible errors in judgment that accompany hypoxia. Night vision is particularly sensitive to hypoxia and visual impairment can occur at altitudes below 10 000 feet, especially amongst smokers. Non-smokers without any lung disease should consider using oxygen on night flights above 10 000 feet. Smokers will have almost a 40% reduction in night vision at 5 000 feet without oxygen. Regular smokers do adapt to hypoxia by producing more hemoglobin. However, this in turn can lead to thickening of the blood with resulting complications such as deep venous thrombosis and stroke. Quitting smoking Only one fourth of those who try to quit smoking are successful. Many people, especially pilots who tend to be very independent and reluctant to ask for outside help (how often do you ask ATC for help if you are "temporarily misoriented"?), try to quit "cold turkey". This is very difficult, but 80% of the successful quitters use this method. Heavy smokers who are successful often do so using a combination strategy of counseling, support group, nicotine patches or gum and possibly, medications in pill form. Unfortunately, not all of the medications available are allowable by the FAA or some CAA while flying. There is good reason behind these policies, yet flexibility should be allowed for pilots who want to improve their health and still fly. Research shows that a combination of strategies, such as medication, counseling, alternate activities and participation in support groups, is the most effective method for long term smoking cessation.