Intravenous colistin-induced acute respiratory failure: A case report and a review of literature.

The emergence of multi-drug-resistant gram negative bacillary infections has regained popularity of ancient drugs such as polymyxins. We report a case of acute respiratory failure induced by use of intravenous colistimethate, which is one of the forms of polymyxin. The patient is a 31 year old female with paraplegia due to spina bifida who underwent excisional debridement of large lumbosacral decubitus ulcer with osteomyelitis infected with pan-resistant Pseudomonas aeruginosa and MRSA. Six days after initiation of intravenous colistimethate and vancomycin, she developed acute respiratory failure requiring mechanical ventilation. Pan-culture was negative including a chest radiograph. V/Q scan showed low probability for pulmonary embolism. Echocardiogram showed normal right ventricle with no strain or pulmonary hypertension. Colistimethate was discontinued. Within 24 hours, she was extubated. In the early years after introduction of polymyxin, there were several reports of acute respiratory paralysis. The mechanism is thought to be noncompetitive myoneuronal presynaptic blockade of acetylcholine release. Though a direct causal relationship for respiratory failure is often difficult to establish in current era with multiple co morbidities, the timeframe of apnea, acuity of onset as well as rapid recovery in our case clearly point out the causal relationship. In addition, our patient also developed acute renal failure, presumably due to colistimethate induced nephrotoxicity, a possible contributing factor for her acute respiratory failure. In summary, colistimethate can induce acute neurotoxicity including respiratory muscular weakness and acute respiratory failure. Clinicians should consider its toxicity in the differential diagnosis of acute respiratory failure especially in critically ill patients.