Table 2.

Respiratory event outcomes by body mass index group and neuraxial morphine dose

Type of event	BMI ≥40 kg/m2 n=1945	BMI <40 kg/m2 n = 9382	Odds ratioa (95% CI)	P-valuea
Intubation performed	2, 10.3 (2.8 to 37.4)	0, 0.0 (0.0 to 4.1)	Inf (0.9, Inf)	0.029
Naloxone administered	2, 10.3 (2.8 to 37.4)	5, 5.3 (2.3 to 12.5)	1.9 (0.2 to 11.8)	0.344
Rapid response called	1, 5.1 (0.9 to 29.1)	6, 6.4 (2.9 to 13.9)	0.8 (0.0 to 6.6)	1.000
Total events	5, 25.7 (11.0 to 60.0)	11, 11.7 (6.5 to 21.0)	2.2 (0.6 to 6.9)	0.174
Type of event	BMI ≥30 kg/m2 n = 7092	BMI < 30 kg/m2 n = 4235	Odds ratioa (95% CI)	P-valuea
Intubation performed	2, 2.8 (0.8 to 10.3)	0, 0.0 (0.0 to 9.1)	Inf (0.1 to Inf)	0.532
Naloxone administered	5, 7.1 (3.0 to 16.5)	2, 4.7 (1.3 to 17.2)	1.5 (0.2 to 15.7)	1.000
Rapid response called	5, 7.1 (3.0 to 16.5)	2, 4.7 (1.3 to 17.2)	1.5 (0.2 to 15.7)	1.000
Total events	12, 16.9 (9.7 to 29.6)	4, 9.4 (3.7 to 24.3)	1.8 (0.5 to 7.6)	0.439
Type of event	High-dose neuraxial morphineb (n = 6390)	Low-dose neuraxial morphineb (n = 4937)	Odds ratioa (95% CI)	P-valuea
Intubation performed	1, 1.6 (0.3 to 8.9)	1, 2.0 (0.4 to 11.5)	0.8 (0.0 to 60.6)	1.000
Naloxone administered	4, 6.3 (2.4 to 16.1)	3, 6.1 (2.1 to 17.9)	1.0 (0.2 to 7.0)	1.000
Rapid response called	3, 4.7 (1.6 to 13.8)	4, 8.1 (3.2 to 20.8)	0.6 (0.1 to 3.4)	0.478
Total events	8, 12.5 (6.3 to 24.7)	8, 16.2 (8.2 to 31.9)	2.2 (0.6 to 6.9)	0.623

BMI: body mass index. All incidences are reported as n (total number of patients), estimated incidence per 10 000 with 95% confidence interval [CI], calculated using the Wilson binomial method.

^aOdds ratios and P-values were computed using the Fisher’s exact method.

^bHigh and low neuraxial doses as defined by the Society for Obstetric Anesthesia and Perinatology Respiratory Monitoring Guidelines (high-dose intrathecal >0.15 mg, low-dose intrathecal ≤0.15 mg, high-dose epidural >3 mg, low-dose epidural ≤3 mg).¹³