Table 2.

Characteristic analysis of the categorical risk factors associated with post-extubation negative pressure pulmonary edema (NPPE)

Categorical variables	Case (n = 16)		Matched controls (n = 131)		P value
	n	%	n	%
Male	10	62.5	61	46.6	< 0.001*
ASA PS					0.174
I–II	14	87.5	101	77.1
III–IV	2	12.5	30	22.9
Emergency operation
Yes	4	25.0	16	12.2	0.003*
Anesthetic technique					< 0.001*
ETGA	14	87.5	85	64.9
LMA	2	12.5	46	35.1
Difficult airway
Yes	0	0	17	13.0	< 0.001*
Type of inhaled anesthetic					0.016*
Desflurane	5	31.3	18	13.7
Sevoflurane	11	68.7	107	81.7
Active smoker
Yes	9	56.3	26	20.0	< 0.001*

ASA PS American Society of Anesthesiologists Physical Status, ETGA endotracheal tube general anesthesia, LMA laryngeal mask anesthesia. Data were analyzed by chi-square test and are shown as number (percent). *P < 0.05 is considered statistically significant