A 25 year old overweight female was given fentanyl- pancuronium anesthesia for surgery. After surgery and extubation, she was observed to have limited movement of the upper body and chest wall in the recovery room. She was conscious and alert but the voluntary respiratory effort has limited. Her blood pressure and heart rate were normal. The likely diagnosis is -
Incomplete reversal of pancuronium Pulmonary embolism Fentanyl-induced chest wall rigidity Respiratory depression