The influence of residual neuromuscular block on the incidence of critical respiratory events. A randomised, prospective, placebo-controlled trial.

CONTEXT

Residual paralysis is associated with post-operative pulmonary complications, including critical respiratory events.

OBJECTIVE

We determined the incidence of critical respiratory events, such as hypoxaemia, in patients with minimal residual neuromuscular blockade and compared these data with those from patients with full recovery of blockade.

DESIGN

Randomised, prospective, placebo-controlled trial.

SETTING

Single centre; Rostock, Germany, from January 2007 to February 2008.

PATIENTS

One hundred and thirty-two adult patients, aged 18-80 years, with the American Society of Anesthesiology I-III physical status, undergoing orthopaedic surgery under general anaesthesia, including rocuronium to produce neuromuscular blockade; 114 patients were randomised to one of two groups: neostigmine group (neostigmine 20 μg kg-1) or placebo group (saline).

INTERVENTIONS

In the patients in the neostigmine group, the tracheal tube was removed at a train-of-four (TOF) ratio of 1.0; in the patients in the placebo group, the trachea was extubated at a TOF ratio less than 1.0, but without fade in TOF and double-burst stimulation (DBS). Neuromuscular monitoring was assessed simultaneously with qualitative TOF/DBS monitoring, and with quantitative calibrated acceleromyography. Critical respiratory events, such as hypoxaemia, were assessed in the post-anaesthesia care unit.

MAIN OUTCOME MEASURES

Forty-five patients (39.5%) became hypoxaemic (SaO2 < 93%); there was a significant difference between the groups (29 patients in the placebo group versus 16 in the neostigmine group; P = 0.021).

RESULTS

In the neostigmine group, all patients were extubated at a TOF ratio of 1.0. In the placebo group, the median TOF ratio was 0.7 (range: 0.46-0.9; P < 0.001). The median time for spontaneous recovery in the placebo group was 16 min (range 3-49 min). Neostigmine 20 μg kg was effective in antagonising rocuronium-induced blockade without fade in TOF and DBS.

CONCLUSION

In this randomised, prospective, placebo-controlled trial, minimal residual block was associated with hypoxaemia in the post-anaesthesia care unit. Neostigmine 20 μg kg was effective in antagonising rocuronium-induced (minimal) blockade.