Opioid Overdose

Opioid poisoning occurs when excessive opioid agonist activity at µ-opioid receptors suppresses the brainstem’s respiratory drive. The patient breathes more slowly and shallowly, responds less effectively to rising carbon dioxide, and may eventually stop breathing. Falling ventilation then causes hypoxia, which can progress to cyanosis, worsening confusion, loss of consciousness, and cardiac arrest. The same opioid effect commonly produces constricted or pinpoint pupils and sedation. A reduced level of consciousness can further obstruct the airway when the tongue, secretions, or vomit limit air movement. That is why a patient with a pulse can still be in immediate danger: the reversible threat is inadequate ventilation, not simply drowsiness. Respiratory rate alone is not enough. Notice the depth and effort of each breath, airway sounds, skin or lip colour, responsiveness, and whether the patient can maintain an open airway. A slow rate with poor chest movement is an emergency even if the monitor still shows a heart rate.