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.

Table 2 Effect of CO₂ insufflation vs air insufflation (mean ± SD)

	CO2 group	Air group	P value
Gas volume in the GI tract
Immediately after ESD (mL)	803 ± 371	1173 ± 580	0.0128
Next day (mL)	300 ± 136	304 ± 215	0.9449
End-tidal carbon dioxide partial pressure (EtCO2) measurements
Baseline EtCO2 level (mmHg)	38.2 ± 3.6	38.1 ± 4.1	0.7543
Maximum EtCO2 level (mmHg)	45.9 ± 4.1	44.3 ± 6.7	0.8562
Oxygen saturation (SpO2) measurements
Baseline SpO2 level (%)	98.9 ± 1.3	98.4 ± 1.0	0.2762
Minimum SpO2 level (%)	93.7 ± 3.4	93.9 ± 2.3	0.8198
Sedative drugs
Propofol dose (mg)	537 ± 258	610 ± 533	0.5655
Pentazocine hydrochloride dose (mg)	27.2 ± 4.5	27.1 ± 5.8	0.9658
Droperidol used, No. of patients	5	2	0.4859
Droperidol dose (mg)	3.0 ± 1.1	2.5 ± 0.0	0.5761

Table 3 Clinical course

	CO2 group	Air group	P value
Fever ≥ 38 °C	8.3%	9.1%	0.6652
Duration of fever ≥ 38 °C (d)	1.5 ± 0.7	2.0 ± 1.4	0.6984
Duration of fasting, d	2.4 ± 0.8	2.1 ± 0.2	0.1639
Complications
Perforation	0%	0%	-
Post-procedure hemorrhage	0%	0%	-
Esophageal stricture with dysphagia	8.3%	9.1%	0.6652
Pneumonia	0%	0%	-
Death	0%	0%	-