Signs and symptoms
In surgery
Symptoms include:
Hypotension
Shortness of breath

In divers
Symptoms of arterial gas embolism include:
Loss of consciousness
Cessation of breathing
Vertigo
Convulsions
Tremors
Loss of coordination
Loss of control of bodily functions
Numbness
Paralysis
Extreme fatigue
Weakness in the extremities
Areas of abnormal sensation
Visual abnormalities
Hearing abnormalities
Personality changes
Cognitive impairment
Nausea or vomiting
Bloody sputum
Symptoms of other consequences of lung overexpansion such as pneumothorax, subcutaneous or mediastinal emphysema may also be present. Causes
Interventional procedures
Interventional radiology procedures, cardiac, and neurosurgical procedures can predispose to air embolism. Besides, increasing use of pump injectors for contrast delivery, and percutaneous intervention to the lungs also increases the risk of air embolism. Decompression illness
Gas embolism is a diving disorder experienced by underwater divers who breathe gases at ambient pressure, and can happen in two distinct ways:

Pulmonary barotrauma:  Air bubbles can enter the bloodstream as a result of gross trauma to the lining of the lung following a rapid ascent while holding the breath; the air held within the lung expands to the point where the tissues tear (pulmonary barotrauma). This is easy to do as the lungs give little warning through pain until they do burst. The diver will usually arrive at the surface in pain and distress and may froth or spit blood. A pulmonary barotrauma is usually obvious and may present quite differently from decompression sickness. Decompression sickness: Inert gas bubbles form in the bloodstream if the gas dissolved in the blood under pressure during the dive is not allowed sufficient time to be eliminated in solution on ascent.
Patients become symptomatic around the age of 10. The weakness attacks in hyperPP are relatively short lasting, and range from minutes to hours. The attacks can happen upwards of ten times per month.Hypo-kalemic PP (hypoPP) is associated with low potassium levels. The onset of hypoPP occurs between the ages of 15 and 35. The prevalence of hypoPP is estimated to 1/100,000. HypoPP can be triggered by many external factors such as stress, high-sugar diet, and rest after exercise. During hypoPP attacks, the serum potassium concentrations can drop to less than 3 mM. Furthermore, hypoPP attacks are considerably longer lasting than hyperPP. As exercise is a trigger for periodic paralysis attacks, recently there is more research going into the physiological changes that accompany exercise including changes in blood pH. Diagnosis
This disease is unusually difficult to diagnose. Patients often report years of wrong diagnosis and treatments that made them worse instead of better. Part of this may be that migraines are present in up to 50% of patients and can cause a confusing array of symptoms including headaches, speech difficulties and visual, auditory or sensory auras. DNA testing is available for only a half dozen common gene mutations, while dozens of known mutations are possible but are not routinely tested. Electromyography (EMG) findings are not specific but the McManis Protocol, also called the Compound Muscle Amplitude Potential test (CMAP) can be used by a skilled neurologist capable of utilizing the EMG, which can give assistance in diagnosing several of these PP disorders.