Patient 2 was readmitted to the ICU 2 weeks later with evidence of further severe sepsis, including hypotension, fever, and leukocytosis. His recent microbiologic results included MDR K pneumoniae (blood cultures, as well as tracheal aspirate and urine), resistant Bacteroides fragilis (blood cultures), and MDR Escherichia coli and P aeruginosa (abdominal fluid collection). Because his condition was worsening and he was currently being treated with tigecycline, levofloxacin, meropenem, metronidazole, and fluconazole, a consensus decision was made to administer a test dose of polymyxin under careful monitoring in the ICU, because the previous diagnosis of a polymyxin-induced neuromuscular weakness had been suspected but not proven and the therapeutic alternatives were limited. Before the infusion, his respiratory rate was 13 to 17 breaths/min, with an Sao2 of 100% on oxygen by nasal cannula. Two hours after commencing the infusion of polymyxin B, the patient developed a witnessed respiratory arrest requiring emergency airway management (including endotracheal intubation) followed by extubation without sequelae the next day. Polymyxin infusion rates were not documented in either of these cases; however, the pharmacy label indicated a 90-min infusion time.