Force measurement
At baseline, the required force was applied in 9 (30%) and 8 (27%) participants for “awake” and “anaesthetised” patients respectively. Eight (27%) participants applied less than the force required to prevent aspiration for “awake” patients and 18 (60%) applied less than the required force for “anaesthetised” patients. Thirteen (43%) participants applied forces greater than recommended for “awake” patients and 4 (13%) participants applied greater than recommended force for “anaesthetised” patients (Figure 5).
The LMM (random coefficient) had the best model fit as adjudged by the information criteria for evaluating the difference in applied force according to the 3 different teaching methods (Table 3). Baseline cricoid pressure forces was a weak determinant of post-teaching cricoid pressure forces (P= =0.053). LMM co-efficient and difference in predicted force estimates for the biofeedback, nose and syringe methods in “awake” and “anaesthetised” patients are shown in Tables 3 and 4.
Model estimates and marginal predictions of post-teaching forces between the 3 teaching methods and in “awake” vs “anaesthetised” patients yielded considerable differences in applied cricoid pressure. Importantly, the biofeedback method led to predicted forces within the recommended limit for both “awake” and “anaesthetised” patients. Graphical representation of predicted force is displayed in Figure 6.