A randomized control trial comparing train of four ratio ≥0.9 to clinical assessment of return of neuromuscular function before endotracheal extubation on critical respiratory events in adult patients undergoing elective surgery at the Aga Khan University Hospital, Nairobi

Background: There is increasing evidence that the incidence of postoperative residual paresis after using neuromuscular blockers ranges from 24 to 50% in post anaesthesia care unit and is associated with postoperative complications such as critical respiratory events as evidenced by hypoxia, hypoventilation and upper airway obstruction. Quantitative neuromuscular monitoring (such as the assessment of Train of four (TOF) ratio) and reversal of neuromuscular blockers has been shown to reduce postoperative residual paresis. There are very few outcome studies on effect of residual paresis in Post anaesthesia care unit (PACU). There are no published randomised control trials investigating whether using a TOF ratio ≥0.9 before endotracheal extubation compared to clinical assessment of return of neuromuscular function reduces the incidence of critical respiratory events in PACU. Primary Objective: To determine whether using TOF ratio ≥0.9 compared to clinical assessment of return of neuromuscular function before endotracheal extubation reduces the incidence of critical respiratory events in PACU Secondary objectives: To determine incidence and severity of hypoxia in PACU. To determine incidence of upper airway obstruction in PACU Study Design: Randomised, prospective, double blinded control trial Setting: Operating theatres of the Aga Khan University hospital Nairobi Population: Adults, aged 18-65 years ASA physical status I and II undergoing elective surgery under general anaesthesia. Sample size: 168 patients randomised to TOF ratio group and clinical assessment group, 84 per group. Methods: Patients requiring general anaesthesia for elective surgery with cisatracurium as the muscle relaxant were randomised into 2 groups using computer generated numbers. Group 1 were patients who required a TOF ratio of ≥0.9 before extubation. Group 2 patients were extubated based on clinical assessment of return of adequate neuromuscular function by the anaesthetist as is the standard of practice at the Aga Khan University hospital Nairobi. General anaesthesia was standardised in both groups. Both the investigators and patients were blinded during the study. Once the patient was transferred to PACU, oxygen saturation (SP02), respiratory rate and any signs of upper airway obstruction as demonstrated by stridor, laryngospasms or requirement of any airway manipulation was recorded for the first 30 minutes. Duration of anaesthesia and surgery was also recorded. Patient demographics were recorded and analysed. vii Results: There was no statistical difference between the 2 groups in terms of patient demographics, duration of surgery and anaesthesia and duration since last muscle relaxant was given. In terms of hypoxia on arrival in PACU, the incidence of mild hypoxia (SPO2 90-93%) was 11% in clinical assessment group versus 5% in TOF group P-value 0.149 while severe hypoxia (SPO2 \u3c90%) was 19% versus 10% P-value 0.078. During the first 30 minutes in PACU, the incidence of mild hypoxia (SPO2 90-93%) was statistically significant between the 2 groups (12% in clinical assessment group versus 1% in TOF group, P-value 0.005) while severe hypoxia (SPO2 \u3c90%) was 7% versus 5%, P-value 0.373. The incidence of upper airway obstruction was statistically significant between the two groups (45% in clinical assessment group versus 14% in TOF group P-value\u3c0.0001 for patients requiring airway maneuver, 21% versus 2% P-value \u3c0.0001 for those who required tactile stimulation and 31% versus 12% were snoring, P-value 0.003. Logistic regression analysis revealed TOF group was less likely associated with mild hypoxia (OR 0.09 95% CI 0.01-0.71 P-value 0.023), tactile stimulation (OR 0.09 95% CI 0.02-0.40 P-value 0.002), airway manuever (OR 0.20 95% CI 0.10-0.43 P-value \u3c0.001) and snoring (OR 0.30 95% CI 0.13-0.68 P-value 0.04). Conclusion: There is a lower incidence of critical respiratory events in post anaesthesia care unit with the use of neuromuscular monitoring using TOF ratio ≥0.9 to assess neuromuscular function before endotracheal extubation compared with the use of clinical assessment method