Diving Medicine - Causes and Treatment

Introduction

With the invention of international airlines, people could travel for recreational activities. The availability of self-contained underwater breathing apparatus (SCUBA) for civilian use has attracted people to utilize diving as a recreational experience. In recent years, recreational diving has become a popular recreational activity that millions enjoy. However, immersion of one's body in deep water can cause health complications. Hence, diving medicine deals with health issues caused by diving and the undersea environment.

What Is Diving Medicine?

It is a branch of medicine that includes research, diagnosis, treatment, and prevention of health complications caused by the undersea environment. The divers experience various systemic effects due to high pressure. Free or scuba diving, even for small depths, can cause stress on the ears, lungs, and cardiovascular system. Individuals with previous medical illnesses, diving accidents, and low functional reserve (lung volume) affect divers adversely.

What Are the Factors Affecting Diving?

• Apnea and Respiratory Drive: The factors that affect breath holding are lung volume, oxygen consumption rate, and carbon dioxide tolerance rate. In deep water diving, lack of oxygen reserve reduces respiratory drive (intensity of lung output), resulting in loss of consciousness.

• Pressure: Volume Changes in Diving: In underwater sea diving, a slight increase in depth can significantly raise pressure due to high water density. If pressure changes occur during diving, the divers develop barotrauma, cardiac syncope (loss of consciousness), or pulmonary edema (excess fluid in the lung).

• Solubility of Gas in Liquids: SCUBA tank is predominantly composed of nitrogen gas that dissolves in blood and body tissues. During diving, high partial pressure (force exerted by gas molecules) of nitrogen leads to nitrogen narcosis.

• Immersion Diuresis: Immersion in water causes a venous return to the heart. To prevent overload on the heart. Heart muscle secretes peptides to cause diuresis. The loss of water volume through diuresis and expired air changes blood properties resulting in decompression sickness.

What Are the Medical Prerequisites for Diving Fitness?

Divers between 18 to 40 years old must undergo medical evaluation every three years. Individuals with few medical illnesses must undergo medical evaluation every year. Most diving operators require divers to have diving fitness certifications.

The diving fitness evaluation includes detailed history taking and physical evaluation. The individuals must undergo tests like:

1. ECG (electrocardiography) at rest.

2. Pulmonary function test (measures lung function).

3. Evaluation of physiologic reserve (ability to adapt to stresses) with a cycle ergometer (stationary bike to measure active, passive, and resistant exercise capabilities).

What Are the Medical Disorders That Prohibit Diving?

• Disorders of Ear and Paranasal Sinuses: The mucosal edema in the middle ear caused by allergies affects communication with the nasopharynx (nasal pathway) and oropharynx (oral path). During diving, it can cause difficulties in pressure equalization, leading to pain, exudate formation, and hemorrhage (bleeding). This ultimately causes eardrum perforation causing water to seep into the middle ear, causing disequilibrium, vomiting, and disorientation.

• Dental Problems: Re-expansion of air trapped under fillings and temporary crowns can cause severe toothache during the diver's ascent.

• Eye Disorders: The eye is essential to visualize underwater, read instruments, and avoid danger. Individuals that have undergone cataracts (clouding of eye lens) or LASIK (Laser-assisted in situ keratomileusis) are contraindicated to dive until completely healed. Individuals with narrow-angle glaucoma (which can cause sudden and permanent eyesight loss), advanced chorioretinal vascular disease (vascular changes of the retina), and macular degeneration (loss of center of vision field) are unfit for diving.

• Lung Disorders: Optimal airways and lungs are essential for divers. Individuals with cold or bronchitis (swelling of bronchus) secrete mucus that can lead to air entrapment in alveoli causing barotrauma. Individuals with pulmonary emphysema (chronic lung disease), COPD (chronic obstructive pulmonary disease), and uncontrolled or partially controlled asthma are unfit to dive.

• Cardiac Disorders: Individuals with cardioverter defibrillators (devices to detect and stop irregular heartbeat), biventricular pacemakers (implanted devices to treat heart failure), and diseases of the cardiac structure are unfit for diving. This condition can cause severe arrhythmia (irregular heartbeat), resulting in syncope or hypertensive edema. However, heart patients with excellent cardiac functional reserve and rate control are fit to dive but require yearly evaluations. The heart conditions that require yearly medical evaluation include coronary heart disease (damage to heart blood vessels), angina pectoris (chest pain), peripheral arterial occlusive disease, hypertension, and implanted pacemaker.

What Are the Medical Conditions Caused by Diving?

• Barotrauma: The condition commonly affects the middle ear. It can cause pain, bleeding, perforation, and damage to the tympanic membrane. Entrapment of expanding gasses in the middle ear, sinus, or external ear during ascent or descent can lead to ear damage. Few individuals may develop pulmonary barotrauma due to gas entrapment in alveoli, causing lung rupture. The gas escaping from lung rupture can further cause mediastinal or subcutaneous emphysema (air accumulation beneath the skin), pneumothorax (collapsed lung), or embolization in the left side of the heart.

• Non-barotraumatic Ear Conditions: Unequal volumes of air in the middle ear during ascent or descent can stimulate the vestibular apparatus (senses body orientation), resulting in a temporary feeling of vertigo (feeling of off balance), nausea, and disorientation. The symptoms resolve when equilibrium of the middle ear is achieved. Repeated immersion can macerate the external ear causing the swimmer's ear.

• Decompression Sickness: It is a diving emergency. Decompression sickness is caused by the emergence of nitrogen gas dissolved in blood and tissues during ascent. Much gas released compared to expiration can lead to bubble formation. A small number of bubbles are expelled through the lungs. However, the critical level of bubbles formed causes decompression sickness.

• Arterial Gas Embolism: It manifests as severe decompression sickness or pulmonary tear. The air bubbles occlude terminal arteries, predominantly of the brain and spinal cord. The symptoms develop during ascent or when the diver reaches the surface.

• Divers Accidents: Drowning is caused by underlying cardiac conditions or accidents.

How to Manage Diving Disease?

• Barotrauma: Middle ear, sinus, or outer barotrauma without perforation resolved without treatment. Divers must avoid diving until completely healed. Ear doctors treat perforations.

• Nonbarotraumatic Ear Conditions: Swimmer's ear is resolved with astringent ear drops. Some patients require steroids or topical mixed antibiotics. Severe cases are treated with systemic antibiotics.

• Decompression Sickness: The risk of decompression sickness can be reduced by extending ascent time by slow ascent and taking regular breaks. Safety protocols must be followed. Once diagnosed, individuals with decompression sickness must be administered 100 percent oxygen. Hyperbaric oxygen therapy is a standard treatment administered.

• Arterial Gas Embolism: Severe decompression illness can be treated with 100 percent oxygen or pressure-chamber treatment.

What Are the Conditions Caused by Unbalanced Gasses?

• Nitrogen Narcosis: The condition is caused by the anesthetic effect of nitrogen gas. The individuals experience mild euphoria, sleepiness, illusions, and impaired judgments.

• Hypoxia: Condition caused by lack of oxygen in the body. Impaired judgments, muscular weakness, drowsiness, impaired vision, depression, and death are some symptoms.

• Pulmonary Oxygen Toxicity: Lung damage caused by excess inhalation of oxygen. During auscultation, individuals experience trickle-in throat, cough, fever, crackles, or wheezing.

• Hypercapnia: Excess carbon dioxide present in the bloodstream causes hypercapnia. Symptoms include throbbing headache, flushing, dizziness, rapid heartbeat, bradycardia, and loss of consciousness.

• Hypocapnia: Decrease in alveolar and blood carbon dioxide levels. Individuals present with hyperventilation, dizziness, muscle spasm, anxiety, and tingling sensation.

Conclusion

Since diving has been gaining popularity worldwide, Doctors need to understand the medical conditions associated with diving. All divers must be evaluated to obtain diver fitness certification, irrespective of their health status. Divers who spend time underwater are at high risk for health complications. Treating the condition at the earliest can prevent the worsening of health.