decompression sickness, a painful, sometimes fatal syndrome caused by the formation of nitrogen bubbles in the tissues of divers, caisson workers, and aviators who move too rapidly from environments of higher to those of lower atmospheric pressures. Nitrogen breathed in air under pressure dissolves in tissue fluids. When ambient pressure is reduced too rapidly, nitrogen goes out of solution faster than it can be circulated to the lungs for expiration. Gaseous nitrogen then accumulates in the joint spaces and peripheral circulation, impairing tissue oxygenation. Also called bends, caisson disease, diver’s palsy, diver’s paralysis. Compare barotrauma. ▪ OBSERVATIONS: The physiologic effects include profound fatigue, disorientation, severe pain, and syncope. There are no specific laboratory tests for decompression sickness. ▪ INTERVENTIONS: When available, 100% oxygen is administered. Treatment entails rapid return of the patient to an environment of higher pressure (hyperbaric therapy) followed by gradual decompression. Rehydration with saline or Ringer’s lactate solution is often required. ▪ PATIENT CARE CONSIDERATIONS: Relapses can occur without hyperbaric therapy even when patients respond well to oxygen and hydration. Admission to a facility with the capacity to administer hyperbaric therapy is a priority.