Clinical Use of an Automated SBP-Responsive Pneumatic Tourniquet: A Single-Center Retrospective Study

Summary

This retrospective study evaluated an automated systolic blood pressure (SBP)-responsive pneumatic tourniquet in 203 upper-extremity procedures. The system provided reliable hemostasis with individualized cuff pressures, stable perioperative hemodynamics, and no observed postoperative neurovascular or cutaneous complications.

Abstract

Conventional pneumatic tourniquets typically rely on fixed empirical pressures that do not account for patient-specific vascular characteristics or dynamic hemodynamic changes, potentially exposing tissues to unnecessary mechanical and ischemic stress. This single-center retrospective cohort study evaluated the clinical performance and safety of an automated systolic blood pressure (SBP)-responsive pneumatic tourniquet in 203 consecutive eligible patients who met the predefined inclusion and exclusion criteria and underwent upper-extremity surgery between January 2023 and September 2024. Continuous or high-frequency SBP measurements were synchronized with cuff-pressure waveforms to characterize real-time closed-loop pressure modulation. Primary outcomes included hemostatic effectiveness and breakthrough bleeding, while secondary outcomes included cuff-pressure behavior, the relationship between SBP and cuff pressure, perioperative hemodynamic stability, and postoperative neurologic or cutaneous complications. The mean tourniquet cuff pressure was 39.61 ± 2.41 kPa (approximately 297 ± 18 mmHg), with values ranging from 34 to 46 kPa. A significant positive correlation was observed between preoperative SBP and cuff pressure (r = 0.706, p < 0.001). Hemostasis was consistently effective, with no breakthrough bleeding observed (0%; 95% CI, 0%–1.8%). Perioperative blood pressure showed only modest fluctuations, and no postoperative neurologic deficits, paresthesia, skin injury, or distal perfusion abnormalities were identified. These findings suggest that a fully automated SBP-responsive tourniquet can provide reliable hemostasis, dynamically maintain physiologically appropriate occlusion pressures, and achieve a favorable short-term safety profile without Doppler-based calibration or manual pressure adjustment, supporting its potential as an individualized and workflow-efficient approach to surgical tourniquet management.

Introduction

Tourniquets are indispensable in orthopedic, hand, and reconstructive surgery, where a bloodless operative field enhances visualization, facilitates precision, and reduces operative time¹. Despite their ubiquity, modern tourniquet practice still relies largely on empirically fixed inflation pressures, typically 250–350 mmHg for upper-limb procedures². These values are simple to apply but are inherently insensitive to individual vascular anatomy, limb geometry, soft-tissue compliance, and real-time hemodynamic variability³. A substantial body of experimental and clinical literature has demons....

Protocol

Ethical approval was obtained from the Institutional Review Board of The First Affiliated Hospital, Zhejiang University School of Medicine (Approval No. IIT20251355B). Given the retrospective nature of the study and the use of de-identified data collected from existing medical records, the requirement for written informed consent was waived by the Institutional Review Board. The tools used in the protocol are listed in the Table of Materials.

1. Study design and setting

This retrospective cohort study was conducted at The First Affiliated Hospital, Zhejiang University School of Med....

Results

During the study period, 221 consecutive patients undergoing upper-extremity surgery with the automated SBP-responsive pneumatic tourniquet were screened for eligibility. Of these, 18 were excluded: 2 because of active dermal lesions at the cuff site, 4 because of peripheral vascular disease, 5 because of uncontrolled hypertension or clinically significant cardiovascular instability, 3 because of pre-existing peripheral neuropathy, and 4 because of incomplete perioperative hemodynamic or cuff-pressure documentation. The .......

Discussion

Conventional fixed-pressure tourniquets remain widely used despite long-standing recognition of their physiologic mismatch with true arterial occlusion requirements. Because fixed thresholds disregard limb-specific vascular properties and intraoperative blood pressure variability, they frequently apply more pressure than necessary, generating steep radial and longitudinal pressure gradients at cuff edges⁴. These mechanical forces compress peripheral nerves, impair microvascular perfusion, and cont.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Adhesive fixation tape	3M Health Care, St. Paul, MN, USA	Micropore Surgical Tape	Secures monitoring cables and tubing
Automated SBP-responsive pneumatic tourniquet system (STS-I)	Hangzhou Medic Instrument Co., Ltd., Hangzhou, China	STS-I	Closed-loop automatic pneumatic tourniquet system with LOP measurement and SBP-responsive pressure modulation
Disposable non-invasive blood pressure cuff	Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China	Adult NIBP cuff	Continuous perioperative blood pressure monitoring
Elastic limb exsanguination bandage	3M Health Care, St. Paul, MN, USA	Esmarch Bandage	Used for limb exsanguination before cuff inflation
Electronic medical record system	First Affiliated Hospital, Zhejiang University School of Medicine	Institutional platform	Retrieval of perioperative clinical and hemodynamic data
High-frequency linear ultrasound probe	FUJIFILM SonoSite, Bothell, WA, USA	HFL38x Linear Probe	Visualization of upper-extremity peripheral nerves
Local anesthetic solution (Ropivacaine hydrochloride)	AstraZeneca, Cambridge, UK	Naropin	Peripheral nerve block anesthesia
Multiparameter anesthesia monitor	Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China	BeneVision series	Continuous perioperative monitoring of systolic blood pressure, diastolic blood pressure, heart rate, and oxygen saturation
Neurological assessment kit	Wartenberg Neurological Instruments, Germany	Standard neurological kit	Postoperative sensory and motor function assessment
Non-invasive blood pressure module	Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China	Integrated module	Provides real-time systolic blood pressure signals for cuff pressure adjustment
Peripheral nerve block needle	B. Braun Melsungen AG, Melsungen, Germany	Stimuplex Ultra 360	Needle for ultrasound-guided peripheral nerve block
Pneumatic upper-extremity tourniquet cuff	Hangzhou Medic Instrument Co., Ltd., Hangzhou, China	Compatible cuff for STS-I system	Sterile-compatible cuff used for upper-extremity arterial occlusion
Pulse oximeter	Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China	Integrated monitor module	Monitoring distal limb perfusion and oxygen saturation
Statistical analysis software	IBM Corp., Armonk, NY, USA	SPSS Statistics Version 27.0	Statistical analysis of perioperative and hemodynamic data
Statistical computing software	R Foundation for Statistical Computing, Vienna, Austria	R Version 4.3.1	Regression analysis and figure generation
Sterile gauze pads	Winner Medical Co., Ltd., Shenzhen, China	Sterile gauze	Soft tissue protection and intraoperative assistance
Sterile surgical drapes	3M Health Care, St. Paul, MN, USA	Steri-Drape series	Sterile operative field preparation
Sterile surgical gloves	Ansell Healthcare, Melbourne, Australia	GAMMEX Latex Surgical Gloves	Standard sterile surgical protection
Sterile ultrasound probe cover	CIVCO Medical Solutions, Coralville, IA, USA	610-1321	Maintains sterile conditions during regional anesthesia
Surgical hand table	Maquet Getinge Group, Rastatt, Germany	Hand Surgery Table	Provides stable upper-extremity positioning during surgery
Surgical marking pen	Viscot Medical, East Hanover, NJ, USA	Viscot Mini XL	Preoperative identification of cuff placement site
Surgical suction device	Medela AG, Baar, Switzerland	Dominant Flex	Removal of blood or irrigation fluid if required
Tourniquet air tubing connector	Hangzhou Medic Instrument Co., Ltd., Hangzhou, China	STS-I accessory	Connects the cuff to the pneumatic controller
Tourniquet pressure waveform recording software	Hangzhou Medic Instrument Co., Ltd., Hangzhou, China	Integrated software	Real-time recording and storage of cuff-pressure waveforms
Ultrasound system for regional anesthesia	FUJIFILM SonoSite, Bothell, WA, USA	SonoSite Edge II	Ultrasound-guided peripheral nerve block anesthesia