OCOSO2: study protocol for a single-blinded, multicentre, randomised controlled trial assessing a central venous oxygen saturation-based goal-directed therapy to reduce postoperative complications in high-risk patients after elective major surgery

Table 1 Schedule of enrolment, interventions and assessments

	Study period
	Enrolment	Allocation	Post-allocation					Close-out
Timepoint	Pre-anaesthesia consultation	Surgery day	t₁ During surgery	t₂ PACU	t₃ D1 to D5 postop	t₄ D15 postop	t₄ D30 postop	D30 postop
Enrolment:
Eligibility screen	X
Informed consent	X
Allocation		X
Interventions:
Control group: standard care			X
Intervention group: ScvO₂-guided GDT			X
Assessments:
Demographics, comorbidities, surgical risk		X
Haemodynamic, respiratory and neurologic variables Total fluid administration			X
Arterial and venous blood gas analysis, LUS				X
Postoperative complications, CCI					X	X	X
Close-out form								X

Abbreviations: PACU post-anaesthesia care unit, D day, GDT goal-directed therapy, LUS lung ultrasound score, CCI Comprehensive Complication Index

ISSN: 1745-6215