Safety of Intraoperative Use of Muscle Relaxants and Their Reversal Agent Neostigmine

• Impaired gas exchange [ Time Frame: Within 10 min. upon PACU arrival ] [ Designated as safety issue: Yes ]
  Gas exchange is assessed by a ratio of pulse oxymetry oxygen saturation relative to fraction of inspired oxygen. Oxygen saturation at PACU admission is defined as the first oxygen saturation value written by an independent nurse in patients' clinical PACU note.
  
  

• Hospital Length of Stay [ Time Frame: within 100 days after surgery ] [ Designated as safety issue: No ]
  Hospital length of stay is defined as the length from the day of the surgery to hospital discharge.
  
  

• Incidence of postoperative atelectasis [ Time Frame: Within one month after surgery ] [ Designated as safety issue: Yes ]
  Diagnosis of atelectasis will be retrieved from the hospital billing data.
  
  
• Incidence of unplanned postoperative intensive care unit admission [ Time Frame: Within one week after surgery ] [ Designated as safety issue: Yes ]
  Incidence of unplanned postoperative intensive care unit admission due to respiratory failure, pulmonary edema and arrhythmia.
  
  

The investigators' laboratory has recently identified the intraoperative use of intermediate-acting non-depolarizing neuromuscular blocking agents and neostigmine reversal of neuromuscular blockade as independent risk factors for severe postoperative respiratory complications. Additionally, the investigators found that postoperative residual curarization (PORC), defined as a train-of-four ratio less than 0.90 upon postanesthesia care unit (PACU) arrival, is associated with an increased PACU length of stay.

To examine the mechanisms contributing to the association of neuromuscular transmission failure with postoperative respiratory complications, the investigators aim to evaluate in a performance improvement driven initiative to better understand the association between the use of neuromuscular blocking agents and reversal agents with postoperative respiratory complications (see British Medical Journal 2012 Oct 15;345:e6329) if patients presenting with PORC develop subsequently 1) an increased incidence of postoperative impaired gas exchange upon PACU admission and result in 2) an increased hospital length of stay. In addition the investigators evaluated the effects of neostigmine on signs and symptoms of postoperative respiratory dysfunction and an incidence of unplanned postoperative intensive care unit admission.