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 a tertiary hospital in Nairobi|
Adembesa, Isaac; Mung’ayi, Vitalis; Premji, Zulfiqarali & Kamya, Dorothy
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 (PACU) 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 PACU. There is a paucity of published randomized controlled 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.
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
Methods: Onehundred sixty eight adult patients in ASA physical status I and II requiring general anaesthesia for elective surgery with cisatracurium as the muscle relaxant were randomized into 2 groups of 84 each. 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 standardized 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 analyzed.
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 groupversus 5% in TOF group P-value 0.149 while severe hypoxia (SPO2 <90%) 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 <90%) 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<0.0001 for patients requiring airway maneuver, 21% versus 2% P-value <0.0001 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 maneuver (OR 0.20
95% CI 0.10-0.43 P-value <0.001) and snoring (OR 0.30 95% CI 0.13-0.68 P-value 0.04).
Conclusion: Among this population, there is a lower incidence of critical respiratory events in PACU 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
Randomized control trial; neuromuscular function; elective surgery; Nairobi.