Anticipation of the Difficult Airway
Anticipation of the Difficult Airway
A total of 8364 independent preoperative assessments were completed. Incomplete assessments (>4 risk factors not completed) were excluded, resulting in a total of 8075 assessments included in our analysis. Three thousand three hundred and thirty-two (41%) were performed by the experimental group and 4743 by the control group (59%) (Fig. 2). A total of 1560 (17%) of all postoperative assessments (n=9117) were reported as DA.
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Figure 2.
Assessment distribution. DMV, difficult mask ventilation; DDL, difficult direct laryngoscopy; DI, difficult intubation; DSGA, difficult supraglottic airway; DA, difficult airway.
No difficult surgical or invasive airways were reported. The frequency of each particular event was similar between all groups (Fig. 2), and ranged from 7.17% to 8.79% for DMV, 5.59% to 5.64% for DDL, 4.09% to 4.98% for DI, and 1.38% to 1.43% for DSGA.
Results are shown in Table 1 and demonstrate significant differences between the two groups. The experimental group had a higher rate of completion than the control group (94.3% vs 84.3%; P<0.001).
The experimental group correctly predicted a DA in 2397 out of 3471 patients (69.1%). The control group predicted 3551 out of 4984 patients (71.2%) correctly, which was significantly higher (P=0.032) than the experimental group (Table 2).
Prediction accuracy for each day of the study was calculated and graphed as a 30 day moving average for the entire study period (Fig. 3). The multiple logistic regression model created to analyse the differences in the rates of accuracy between resident groups showed significant relationships with both patient factors (age, weight, Mallampati, jaw protrusion, interincisor distance, thyromental distance, sternomental distance, and neck circumference) and resident factors (day of study and cohort). Inclusion in the CA 1–1 cohort was the largest negative predictor of correctness (likelihood estimate −0.62, P=0.001) followed by the CA 2–3 cohort (likelihood estimate −0.36, P=0.0025). Compared with the CA 3 cohort, the odds ratios for both the CA 1–1 (0.267, CI 0.130–0.549) and CA 2–3 (0.347, CI 0.171–0.705) cohorts were statistically significant. Inclusion in the CA 1–2 cohort was associated with a positive likelihood estimate (0.28, P=0.018), but compared with the CA 3 cohort, the odds ratio was not significant (0.660, CI 0.330–1.321). A significant positive likelihood estimate was also noted when the day of the study was used as a predictor (0.00068, P=0.031), indicating a small improvement in correct prediction during the study period.
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Figure 3.
Thirty day moving average of prediction accuracy over duration of study. CA 1–2 are residents who enrolled as first-year residents when the study began and were second-year residents at the end of the study; CA 2–3 are residents who enrolled as second-year residents when the study began and were third-year residents at the end of the study; CA 1–1 are residents who enrolled as first-year residents the second year of the study; CA 3 are residents who enrolled as third-year residents the first year of the study.
Results
A total of 8364 independent preoperative assessments were completed. Incomplete assessments (>4 risk factors not completed) were excluded, resulting in a total of 8075 assessments included in our analysis. Three thousand three hundred and thirty-two (41%) were performed by the experimental group and 4743 by the control group (59%) (Fig. 2). A total of 1560 (17%) of all postoperative assessments (n=9117) were reported as DA.
(Enlarge Image)
Figure 2.
Assessment distribution. DMV, difficult mask ventilation; DDL, difficult direct laryngoscopy; DI, difficult intubation; DSGA, difficult supraglottic airway; DA, difficult airway.
No difficult surgical or invasive airways were reported. The frequency of each particular event was similar between all groups (Fig. 2), and ranged from 7.17% to 8.79% for DMV, 5.59% to 5.64% for DDL, 4.09% to 4.98% for DI, and 1.38% to 1.43% for DSGA.
Completeness of Airway Examination Documentation
Results are shown in Table 1 and demonstrate significant differences between the two groups. The experimental group had a higher rate of completion than the control group (94.3% vs 84.3%; P<0.001).
Overall Recognition of the DA
The experimental group correctly predicted a DA in 2397 out of 3471 patients (69.1%). The control group predicted 3551 out of 4984 patients (71.2%) correctly, which was significantly higher (P=0.032) than the experimental group (Table 2).
Impact on Resident Education
Prediction accuracy for each day of the study was calculated and graphed as a 30 day moving average for the entire study period (Fig. 3). The multiple logistic regression model created to analyse the differences in the rates of accuracy between resident groups showed significant relationships with both patient factors (age, weight, Mallampati, jaw protrusion, interincisor distance, thyromental distance, sternomental distance, and neck circumference) and resident factors (day of study and cohort). Inclusion in the CA 1–1 cohort was the largest negative predictor of correctness (likelihood estimate −0.62, P=0.001) followed by the CA 2–3 cohort (likelihood estimate −0.36, P=0.0025). Compared with the CA 3 cohort, the odds ratios for both the CA 1–1 (0.267, CI 0.130–0.549) and CA 2–3 (0.347, CI 0.171–0.705) cohorts were statistically significant. Inclusion in the CA 1–2 cohort was associated with a positive likelihood estimate (0.28, P=0.018), but compared with the CA 3 cohort, the odds ratio was not significant (0.660, CI 0.330–1.321). A significant positive likelihood estimate was also noted when the day of the study was used as a predictor (0.00068, P=0.031), indicating a small improvement in correct prediction during the study period.
(Enlarge Image)
Figure 3.
Thirty day moving average of prediction accuracy over duration of study. CA 1–2 are residents who enrolled as first-year residents when the study began and were second-year residents at the end of the study; CA 2–3 are residents who enrolled as second-year residents when the study began and were third-year residents at the end of the study; CA 1–1 are residents who enrolled as first-year residents the second year of the study; CA 3 are residents who enrolled as third-year residents the first year of the study.
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