. Author manuscript; available in PMC: 2013 Oct 1.

Published in final edited form as: Crit Care Med. 2012 Oct;40(10):2788–2796. doi: 10.1097/CCM.0b013e31825b8ade

Table 3.

Changes in nighttime sedation dose and odds ratios of liberation from mechanical ventilation ^#

	Percentiles		Successful SBT		Successful extubation
Variables	10^th	90^th	OR (95% CI)	P value	OR (95% CI)	P value
Change in sedative dosing at night
Benzodiazepine dose, mg/hr	−0.19	0.25	0.4 (0.2 – 0.8)	<0.01	0.7 (0.3 – 1.7)	0.38
Propofol dose, mcg/kg/min	−7.7	5.7	0.8 (0.5 – 1.4)	0.43	1.0 (0.6 – 1.6)	0.94
Daytime sedative dosing
Benzodiazepine dose, mg/hr	0	2.4	nonlinear^*	<0.01	nonlinear^*	0.02
Propofol dose, mcg/kg/min	0	40.1	0.4 (0.2 – 1.1)	0.09	1.2 (0.5 – 2.6)	0.67

N=192 observations for extubation model, N=173 observations for SBT model

Because these associations are nonlinear, the magnitude of the associations cannot be summarized using a single odds ratio but are displayed in Figures 2 and 3.

Interpretive example: The odds ratios (ORs) reflect the change in odds of the outcome that was independently associated with a change in the exposure from the 10^th percentile value to the 90^th percentile value. For example, a nighttime increase in benzodiazepine dose of 0.25 mg/hr, compared to a decrease of 0.19 mg/hr, was independently associated with a 60% reduction in odds of successful spontaneous breathing trial on the day following sedative exposure.