Introduction to Diving Fitness
Underwater diving is a physically demanding activity that subjects the body to significant pressure changes. For most healthy individuals, this is a safe and exhilarating experience, but for those with certain medical conditions, it can be extremely dangerous. Understanding the risks is the first step toward safe diving. Medical screening questionnaires are standard practice for a reason: they are designed to flag potential issues that could be exacerbated by the underwater environment.
Respiratory Conditions
Respiratory conditions are among the most serious contraindications for diving because of the risks associated with pulmonary barotrauma. This can occur during ascent if air becomes trapped in the lungs, causing it to expand and potentially rupture lung tissue, leading to a collapsed lung (pneumothorax) or, more dangerously, an arterial gas embolism (AGE).
Asthma
Active or severe asthma is a significant risk factor. The narrowing of airways can lead to air trapping, and the cold, dense air found at depth can trigger an attack underwater. Even controlled asthma requires careful evaluation by a doctor specializing in diving medicine.
Chronic Obstructive Pulmonary Disease (COPD)
COPD, including emphysema, is generally a permanent contraindication. The condition involves structural damage to the lungs and reduces their elasticity, making them prone to rupture from expanding gas during ascent.
History of Spontaneous Pneumothorax
A history of a collapsed lung, particularly if it was spontaneous rather than from an injury, is a major barrier to diving. It often indicates a structural weakness in the lung, such as blebs or bullae, which are highly susceptible to rupturing under pressure changes.
Cardiovascular Conditions
The stress of immersion, cold water, and physical exertion places significant strain on the heart and circulatory system. Any condition that compromises the heart's function is a major risk.
Uncontrolled Hypertension and Heart Disease
Uncontrolled high blood pressure (hypertension), coronary artery disease, heart failure, and a history of significant heart attacks or arrhythmias are all serious concerns. These conditions can lead to sudden incapacitation underwater, such as a heart attack, and can increase the risk of immersion pulmonary edema (IPO).
Atrial Septal Defects and Patent Foramen Ovale (PFO)
Divers with a right-to-left shunt, such as an atrial septal defect or a large PFO, have an increased risk of decompression sickness (DCS). This is because venous gas bubbles, which would normally be filtered by the lungs, can pass through the shunt and enter the arterial circulation, potentially causing neurological DCS or stroke.
Neurological Conditions
Any condition that could lead to a loss of consciousness or impaired judgment underwater is a critical safety issue, potentially leading to drowning or other accidents.
Epilepsy and Seizure Disorders
Epilepsy is considered one of the biggest contraindications for diving. A seizure underwater would almost certainly lead to death by drowning. A person with a history of seizures, even if controlled, must have a prolonged seizure-free period and be medically cleared by a specialist.
History of Stroke or Severe Head Injury
Individuals with a history of stroke or severe head injury that resulted in unconsciousness should be evaluated for residual neurological effects and potential seizure risk before considering diving.
Metabolic and Other Conditions
Diabetes Mellitus (Insulin-Dependent)
For individuals with insulin-dependent diabetes, the risk lies in hypoglycemia (low blood sugar), which can cause confusion, disorientation, or unconsciousness. While some diabetics can dive under strict medical protocols, it requires careful blood glucose management and professional medical supervision.
Pregnancy
Due to the potential for venous gas bubbles to cross the placenta and affect the fetus, diving is not recommended during any stage of pregnancy. There is insufficient research to establish a safe diving protocol for pregnant individuals.
Mental Health Considerations
While often overlooked, mental and psychological fitness is just as important as physical fitness for diving.
Panic Disorders and Claustrophobia
The enclosed feeling of being underwater and dependent on a breathing apparatus can trigger panic attacks in individuals prone to anxiety or claustrophobia. A panic attack underwater is an extremely dangerous scenario that can impair judgment and lead to critical errors.
Severe Depression or Psychosis
Certain mental health conditions, particularly those requiring strong medications, can impair judgment, increase anxiety, or cause erratic behavior, making diving unsafe. The medications themselves may also interact with pressure and nitrogen.
Comparison of Major Contraindications
To highlight the key risks, the following table compares some of the most serious contraindications.
| Condition | Primary Risk Factor | Reason | Risk Level |
|---|---|---|---|
| Active Asthma | Pulmonary Barotrauma | Trapped air in narrowed airways expands during ascent, risking lung rupture. | High |
| Epilepsy | Loss of Consciousness | A seizure underwater leads to loss of control, increasing the risk of drowning. | Extremely High |
| History of Spontaneous Pneumothorax | Pulmonary Barotrauma | Indicates a structural weakness in the lung that is prone to rupture under pressure. | Extremely High |
| Uncontrolled Heart Disease | Sudden Incapacitation | Heart attacks or arrhythmias underwater could be fatal and impede rescue. | High |
| Insulin-Dependent Diabetes | Hypoglycemia | Low blood sugar can cause confusion and unconsciousness, leading to drowning. | High |
| Pregnancy | Fetal Complications | Potential for decompression sickness effects on the developing fetus; research is insufficient. | High |
The Critical Role of Medical Evaluation
It is imperative that any potential diver with a pre-existing medical condition consult a physician who is trained in diving medicine before entering the water. Standard doctors may not understand the unique physiological stresses of the underwater environment. Organisations like the Divers Alert Network (DAN) provide resources and guidelines for both divers and physicians to help make informed decisions. A medical professional can assess individual risk and provide the necessary clearance or advice for safe diving.
Conclusion
In conclusion, the decision of which of the following medical conditions would be contraindicated with regard to diving underwater is not to be taken lightly. Conditions involving compromised respiratory or cardiovascular function, neurological instability, or other factors that could lead to incapacitation are considered major contraindications. While diving can be enjoyed by many, acknowledging and respecting these medical limitations is vital for personal safety and the safety of your dive buddies. Never dive without honestly disclosing your medical history and obtaining professional clearance if required. For authoritative guidance and further reading, consult the Divers Alert Network (DAN) medical resources.
