Effects of small-dose S-ketamine on anesthesia-induced atelectasis in patients undergoing general anesthesia accessed by lung ultrasound: study protocol for a randomized, double-blinded controlled trial

Table 1 The schedule of enrollment, interventions, and assessments

	Study period
	Enrollment	Allocation	Postallocation
Time point	Day − 1	Day 0	T1 (after radial artery puncture)	15 min after intubation (T2)	Before extubation (T3)	2 h after surgery	24 h after surgery
Enrollment
Eligibility screen	X
Informed consent	X
Randomization		X
Allocation		X
Interventions
[Group 1] S-ketamine group			X
[Group 2] Normal saline group			X
Outcome assessment
Total LUS			X	※	X
LUS of 12 chest regions				X
PaCO₂, PaO₂, and PaO₂/FiO₂			X	X	X
P_plat and Cdyn				X	X
Incidence of postoperative complications associated S-ketamine						X	X
Incidence of PPCs						X	X

LUS lung ultrasound scores, P_plat plateau pressure, Cdyn dynamic lung compliance, PPCs postoperative pulmonary complications. ※ primary outcome

ISSN: 1745-6215