Any pregnant woman who would not take any medication or may even avoid drinking coffee in order to protect her baby (fetus) from any unknown risk, will still ask if it is safe to dive during pregnancy?
As a matter of fact, human research is quite defective regarding the direct effect of diving on the fetus, being a passive passenger at depth, but most workers investigating DCS and fetal risk agree that the fetus is not at increased risk.
Let's first discuss the effect of diving on the pregnant mother and then return back to the effect on the fetus.
*During pregnancy, the mother will experience a change in the distribution of her body fluids with the increased amount of interstitial fluids and edema (what is sometimes called the third-space fluids).
As well, her body undergoes an increase of 5% in deposited fat during pregnancy.
The combination between this third –space fluid and increased fat stores will definitely alter both the inert gas intake and elimination times suggesting an increased risk of DCS for a pregnant woman.
*Physiological fluid retention during pregnancy also causes the swelling of the mucous membranes including the naso-pharynx that will render many diving pregnant women decongestants-dependant (nasal drops and tablets) with the inherited risk of rebound congestion (reversed blocks).
*A third problem might be the increased gastro-intestinal symptoms (in 60% of pregnancies) like nausea, vomiting, heart burn and reflux which will make riding a boat a night mare and also will increase the risk of vomiting into the regulator during diving.
*Another problem is the state of vasodilatation (opening of skin blood vessels) which puts the pregnant diver at risk of hypothermia in cool water, and the state of increase in the basal metabolic rate (excessive heat production) which increases the risk of hyperthermia in case of heavy activity in warm water.
*Add to all this the uncomfortable fit of the diving gear as the weight belt and the wet suit on the expanding belly, as well the getting tighter wet suit on the already swollen hands and feet will interfere with the exchange of gases increasing the risks of limb DCS.
The pregnant diver, especially in the last few months, will also have some problems in her movements carrying and balancing heavy equipment and will always suffer the simplest entries and exits to and from the water.
Effect of diving on the fetus:
*A lot of researchers have investigated the effect of DCS done to pregnant animals on the offspring to pressures between 6.4 – 7.1 ata (54 – 61 meters) which is in excess of depths encountered in sport diving. The results suggested an increase in the rate of fetal deformity when exposure (diving) was done in early pregnancy (first trimester) while exposure in the last trimester denoted an increase in the number of still birth of those animals as a result of lacking of the lung filter of the fetal circulation which makes the bubbles pass directly to the brain and heart. These results are still not applicable to humans so far.
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* Another challenge to the diving fetus is the exposure to a hyperbaric oxygen environment simply as the mother goes underwater or more dramatically if the mother will have to be treated from a diving accident in a chamber using oxygen as a breathing gas. Animal studies showed cardiovascular malformations and blindness in delivered babies of pregnant animals who were exposed to hyperbaric oxygen.
*Human data on hyperbaric oxygen and the fetus are very limited, a case was reported to have been treated from CO toxicity while pregnant using hyperbaric oxygen with a 5 weeks later delivery of a normal infant, while a few cases of maternal non-diving related air embolism cases have been treated with hyperbaric oxygen and all fetuses died with no adequate explanation of the definite cause of death!
*Only two surveys have been conducted questioning the outcome of women who dived while pregnant, although no statistical analysis was done, the results suggested higher rates of low birth weight, birth defects, neonatal respiratory difficulties and other problems in the group that continued to dive while pregnant.
*One of the hazards that could harm the fetus underwater is the accidental envenomation of the pregnant mother by a marine animal, undefined fetal toxic effects may follow, and specific antitoxins (if any will exist) will also hold risk.
In view of the elective nature of diving, even though diving during pregnancy does not clearly increase maternal or fetal incidence of DCS or air embolism, the unborn may be at severe risk if a diving accident occurs. Summarizing that has been cited and said,
Pregnant women should not dive.
Dr. Hossam Nasef
Drugs and diving I
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People nowadays learned to depend on drugs either routinely or intermittently to control diseases and to be able to cope with every day's life minor illnesses.
Diving environmental conditions such as cold, spatial disorientation, reduced visibility, inability to localize sound direction, narcotic effect of inert gases in the breathing medium, all of these could change dramatically the effect ( desired or undesired) of the drug taken by the diver.
Another way the drug can exert its effect upon a diver is by changing the rate of uptake or elimination of the inert gas , our best example is dehydration that is caused by certain drugs such as diuretics and alcohol increasing the incidence of decompression sickness.
One of the most common drugs is Aspirin, It interferes with blood clotting mechanism and increase bleeding tendency, an effect that is considered disastrous in inner ear embolism or severe inner ear decompression sickness.
Antihypertensive drugs are ingested by a considerable number of divers now , who were divers long before becoming hypertensive patients, this group of divers are middle aged, experienced divers, though having normal life stress, yet successful and very proud, if you are one of this group, please consult a hyperbaric medicine specialist about your medication, for example a common drug group are ß-blockers that is prescribed by cardiologists ,they have minimal side effects and are well tolerated by many patients, ß-blockers can cause inadequate heart response to exercise, an effect that could be critical in emergency dive situations.
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Another example is oral contraceptives, the hormones that increase the coagualbility of blood predisposing to decompression sickness, so if you are a dive master, diving every day two or three dives, in a warm weather like Hurghada, you have to be very careful from getting dehydrated that adds to coagulability of blood and less efficient circulation predisposing to decompression sickness.
The List is long, there is too much that we do not know about how drugs can interact with our bodies in the hyperbaric environment
It can not simply become you are taking a drug you do not dive !!!
As drugs (natural or synthetic) have become a part of modern life, we have to understand how they act and use them safely while enjoying our dives.
Dr. Hanaa M. Nessim
Drugs and diving II
This time we will mention Recreational drugs, they are drugs, which may be legal or illegal to consume in the country you are living in, they are taken regularly or occasionally on social events, consumed to change mood or alleviate peer pressure. These drugs include Tobacco, Alcohol, Marijuana, Hashish
(Cannabis) and others.
To start with, the most common in use is Tobacco
The main active principal of tobacco is nicotine, the pharmacological generalized effect of which is raising blood pressure, increasing heart rate and restriction of blood flow to the heart muscle ( Coronary vasoconstriction). This obviously lowers physical fitness. (Can you swim 200 meters towing an unconscious diver?)
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Inhalation of tobacco smoke containing nicotine and tar causes bronchospasm
( narrowing of respiratory passages ) as well as more mucus production by the tissue that lines these bronchi adding to more narrowing of Bronchial lumen, this leads to higher possibility of air trapping in lung tissue with the incidence of
pulmonary infection (bronchitis) getting very high, and the possibility
( not remote) of ascent pulmonary barotrauma due to partial air trapping inside the lungs and fatal air embolism.
A whisper for professional divers who are chronic smokers:
How many times last year have you suffered from chronic cough for several days with or without fever (Bronchitis) ?? If more than 2 times and not seasonal, then either quit smoking today or find another job.
To investigate your pulmonary functions, it is recommended to make a
Lung function test during your diving regular medical checks.
Tobacco smoking increases carboxy hemoglobin level to 5-9% in blood , which increases the viscosity of blood with less efficient blood circulation and more likelihood of decompression sickness.
I wish you safe diving.
Dr. Hanaa M. Nessim
