An absolute contraindication for scuba diving refers to a medical condition that presents an unacceptable risk of serious injury or death during a dive. Unlike a relative contraindication, which might allow diving with precautions, an absolute contraindication means diving is not safe under any circumstances due to the physiological stresses of the underwater environment.
Pulmonary Conditions: The Risk of Barotrauma
Pulmonary barotrauma, a lung overexpansion injury, is a significant risk for divers with certain lung conditions. Air trapped in the lungs during ascent can expand and potentially rupture lung tissue, leading to serious complications like arterial gas embolism (AGE) or a collapsed lung (pneumothorax).
Conditions That Prohibit Diving
Certain pulmonary conditions are absolute contraindications for scuba diving due to the risk of barotrauma. These include active asthma, particularly if exercise or cold-induced, as it increases the risk of air trapping. Chronic Obstructive Pulmonary Disease (COPD) also poses a risk by impairing lung elasticity. A history of spontaneous pneumothorax (unless surgically treated on both sides), lung cysts or bullae, and cystic fibrosis involving the lungs are also generally considered absolute contraindications.
Cardiovascular Conditions: The Heart Under Pressure
Scuba diving adds stress to the cardiovascular system, making certain heart conditions dangerous.
Critical Cardiac Disqualifications
Untreated coronary artery disease significantly increases the risk of a heart attack during a dive. Uncontrolled ventricular arrhythmias also pose a high risk of sudden incapacitation. Heart failure and cardiomyopathy are typically absolute contraindications. Conditions like a large patent foramen ovale (PFO) can increase the risk of decompression sickness by allowing bubbles to bypass normal lung filtration. While some with PFO may be cleared after medical review, those with a history of serious DCS should avoid diving.
Neurological and Psychiatric Conditions: Mind Over Water
Neurological and psychiatric issues can lead to loss of control or impaired judgment underwater, with potentially fatal outcomes.
Neurological and Mental Health Barriers
Seizure disorders like epilepsy are a major concern, as the stresses of diving can trigger seizures. An underwater seizure is extremely dangerous. Many guidelines require a long seizure-free period without medication before even considering clearance, which is often denied. Conditions affecting judgment, reality testing, or concentration, such as active psychosis, are absolute contraindications. Panic disorder, severe anxiety, claustrophobia, and agoraphobia can also pose risks underwater. Diving under the influence of drugs or alcohol is prohibited due to impaired judgment.
Other Absolute Contraindications
Pregnancy and ENT Issues
Pregnancy is an absolute contraindication for scuba diving due to the theoretical risk of gas bubbles harming the fetus. The inability to properly equalize middle ear pressure is also a disqualifier because it can cause ear barotrauma, potentially leading to permanent damage or dangerous disorientation underwater. An unhealed perforated eardrum and Meniere's disease, which causes vertigo, are also absolute contraindications.
Comparison of Absolute vs. Relative Contraindications
To clarify the distinction, here is a comparison table outlining key differences:
| Feature | Absolute Contraindication | Relative Contraindication |
|---|---|---|
| Risk Level | Presents an unacceptable, high risk of serious injury or death. | Represents an increased risk that may be mitigated, resolved, or managed. |
| Diving Status | Permanently disqualifies an individual from diving. | May allow for diving after further medical evaluation, treatment, or protocol changes. |
| Example Conditions | Active asthma, uncontrolled seizures, pregnancy, significant cardiac shunts. | Controlled diabetes, hypertension, healed ear surgery (requires evaluation). |
| Physician Stance | A dive medicine physician will advise against diving and will not provide clearance. | Requires a case-by-case assessment by a qualified physician knowledgeable in dive medicine. |
The Critical Importance of Medical Evaluation
A comprehensive medical evaluation by a physician knowledgeable in diving medicine is crucial before diving. This helps identify risks that might not be apparent to the diver. Conditions well-managed on land, like controlled epilepsy, can become dangerous underwater. Full disclosure of medical history is vital for an accurate assessment.
The Need for Honesty
Hiding a medical condition to dive is dangerous for the individual, their buddy, and the dive team. The risks of injury or death are severe. Safety in diving requires honest medical assessment. Resources like the Divers Alert Network (DAN) offer medical consultation for divers and physicians.
Conclusion
While scuba diving is generally safe, certain medical conditions make it incompatible with the underwater environment. Pressure changes, increased gas density, and cold temperatures amplify the risks for individuals with pulmonary, cardiovascular, and neurological issues. Absolute contraindications like pregnancy, uncontrolled seizures, active psychosis, and significant heart or lung disease should never be ignored. Seeking evaluation from a dive medicine specialist is essential for anyone with health concerns to ensure a safe diving career.
