Carbon dioxide insufflation in esophageal endoscopic submucosal dissection reduces mediastinal emphysema: A randomized, double-blind, controlled trial

Table 1 Patient characteristics

	CO2 group	Air group	P value
Total No. of patients	24	22
Sex, M/F	21/3	19/3	0.7460
Age (yr, mean ± SD)	67.5 ± 5.8	72.0 ± 7.2	0.7718
Location1
Cervical esophagus (Ce)	0	0	0.6015
Upper thoracic esophagus (Ut)	2	4
Middle thoracic esophagus (Mt)	17	11
Lower thoracic esophagus (Lt)	4	4
Abdominal esophagus (Ae)	1	3
Histology1
Squamous cell carcinoma	23	19	0.3364
Barrett’s adenocarcinoma	1	3
Histological depth1
EP	5	6	0.1734
LPM	11	9
MM	4	6
SM1	0	1
SM2	4	0
Tumor size (mm, mean ± SD)	26.6 ± 14.4	27.4 ± 22.9	0.8955
Resection size (mm, mean ± SD)	40.0 ± 14.1	42.3 ± 21.2	0.6620
En-bloc resection	24	22	-
R0 resection	22	20	0.9378
HM+	1	1	0.5087
VM+	1	0	0.9649
Ly+	0	0	-
V+	1	3	0.3364
Procedure time (min, mean ± SD)	69.2 ± 28.1	65.0 ± 39.2	0.6847

¹Based on the Japanese Classification of Esophageal Cancer[19]. EP: Carcinoma in situ; LPM: Tumor invades lamina propria mucosa; MM: Tumor invades muscularis mucosa; SM1: Tumor invades upper third of the submucosal layer; SM2: Tumor invades middle third of the submucosal layer or deeper.