Adult bradypnea

Specialty: Respiratory.

• slow breathing in adults
• decreased respiratory rate

Why it occurs

• Acute opiate or sedative intoxication (direct depression of the respiratory centers in the brainstem mediated by mu or GABA receptors)
• Severe intracranial hypertension (as part of the Cushing triad along with hypertension and bradycardia, due to compression of the medulla oblongata)
• Moderate to severe systemic hypothermia (decrease in basal metabolism that depresses central respiratory automatism)
• Severe untreated myxedema or hypothyroidism (generalized slowing of metabolic functions and chemoreceptor control)
• Structural lesions of the brain stem due to cerebrovascular accident (CVA) or trauma (infection of the pneumotaxic and apneustic nuclei)

Initial workup

Continuous monitoring of vital signs; Immediate arterial blood gas (to evaluate severe respiratory acidosis and hypercapnia); Qualitative and quantitative toxicological determination in urine and blood; Simple non-contrast head computed tomography (CT) scan; Electrolytes and complete thyroid profile (TSH, free T4).

Standard management

• Naloxone — opioid antagonist, dose 0.4 mg to 2 mg intravenously, intramuscularly, or subcutaneously, repeatable every 2-3 minutes depending on clinical response
• Flumazenil — benzodiazepine antagonist, administered at a dose of 0.2 mg intravenously over 15 seconds, with a maximum cumulative dose of 1 mg, monitoring the risk of seizures
• Hot physiological solution — infusion at 37-40 °C if associated with severe hypothermia
• Levothyroxine sodium (administered intravenously at doses of 200-400 micrograms in case of verified myxedema coma).