Optimization of surgical tourniquet usage to improve patient outcomes: Translational cross-disciplinary implications of a surgical practice survey.

Tourniquet use is common practice in many millions of orthopaedic procedures annually. Recent reviews of risks and benefits of surgical tourniquet use have primarily involved meta-analyses, many of which have forgone a comprehensive risk-benefit analysis to simply question whether "tourniquet or no tourniquet" use produces improved patient outcomes, often leading to limited, inconclusive, or conflicting results. To investigate further, a pilot survey was undertaken to determine current practices, opinions, and understandings among orthopaedic surgeons in Canada regarding use of surgical tourniquets in total knee arthroplasties (TKAs).

Tourniquet-induced nerve compression injuries are caused by high pressure levels and gradients - a review of the evidence to guide safe surgical, pre-hospital and blood flow restriction usage.

Tourniquets in orthopaedic surgery safely provide blood free surgical fields, but their use is not without risk. Tourniquets can result in temporary or permanent injury to underlying nerves, muscles, blood vessels and soft tissues. Advances in safety, accuracy and reliability of surgical tourniquet systems have reduced nerve-related injuries by reducing pressure levels and pressure gradients, but that may have resulted in reduced awareness of potential injury mechanisms.

Deep venous thrombosis identification from analysis of ultrasound data.

Purpose: The purpose of this research was to determine whether combined ultrasound- and sensor-based compressibility and augmented blood flow measures yielded better results for DVT detection than for the individual measures alone.

Methods: Twenty-six limbs from 19 patients were scanned using a sensorized ultrasound DVT screening system, and compressibility and flow measures were obtained at 125 locations. Results from conventional compression ultrasound examination were used as gold standard, with seven vessels (four patients) positive for DVT.

Surgical tourniquets in orthopaedics.

Higher levels of tourniquet pressure and higher pressure gradients beneath tourniquet cuffs are associated with a higher risk of nerve-related injury. Measurement of limb occlusion pressure can help to minimize tourniquet pressure levels and pressure gradients for individual patients and individual surgical procedures. Selective use of pneumatic, wider, and contoured tourniquet cuffs reduces tourniquet pressure levels and the applied pressure gradients.

Minimizing tourniquet pressure in pediatric anterior cruciate ligament reconstructive surgery: a blinded, prospective randomized controlled trial.

Background: Tourniquet cuff pressures in pediatric patients are commonly set at standard pressures. Recent evidence on adult subjects has shown that safer and more effective cuff pressures can be achieved by measuring limb occlusion pressure (LOP) and using a wide contour cuff. There is little evidence validating these techniques in children.

Real-time vessel segmentation and tracking for ultrasound imaging applications.

A method for vessel segmentation and tracking in ultrasound images using Kalman filters is presented. A modified Star-Kalman algorithm is used to determine vessel contours and ellipse parameters using an extended Kalman filter with an elliptical model. The parameters can be used to easily calculate the transverse vessel area which is of clinical use.

System for deep venous thrombosis detection using objective compression measures.

A system for objective vessel compression assessment for deep venous thrombosis characterization using ultrasound image data and a sensorized ultrasound probe is presented. Two new objective measures calculated from applied force and transverse vessel area are also presented and used to describe vessel compressibility. A modified star-Kalman algorithm is used for feature detection in acquired ultrasound images, and objective measures of vessel compressibility are calculated from the detected features and acquired force and location data from the sensorized probe.

Survey of tourniquet use in orthopaedic foot and ankle surgery.

Background: Tourniquet technique varies among foot and ankle surgeons, and to establish a standard practice guideline the current standard of care should be examined.

Methods: One hundred and forty responses were received after 253 surveys were mailed to American Orthopaedic Foot and Ankle Society (AOFAS) members, concerning type of tourniquets, location, and pressures used.

Results: Cuff pressures most commonly used were 301 to 350 mmHg for thigh cuffs (49% of thigh cuff users) and 201 to 250 mmHG for calf and ankle cuffs (52% of calf cuff users, 66% of ankle cuff users).

Wide contoured thigh cuffs and automated limb occlusion measurement allow lower tourniquet pressures.

We examined the amount of thigh tourniquet pressure that can be reduced from the typical 300 to 350 mm Hg by using a new automated plethysmographic limb occlusion pressure measurement technique. We also examined how much pressure could be reduced by using a wide contoured cuff compared with a standard cuff and if limb occlusion and systolic blood pressures were well correlated. Patients having surgery with a thigh tourniquet were randomized into two groups, one group having surgery with a standard cuff and the other with a wide cuff.

Can a new design of pneumatic compression device reduce variations in delivered therapy for the mechanical prophylaxis of thromboembolic disease after total hip arthroplasty?

Background: Compression devices have been shown to prevent thromboembolic disease. However, the pressures generated may not be the same as the ones recommended by the manufacturer. The purpose of this study is to investigate a new sequential compression device with feedback to maintain optimal therapy, and to determine whether therapy is improved with this new device.

Survey of tourniquet use in podiatric surgery.

Tourniquet use in foot and ankle surgery is common practice; however, the technique varies among foot and ankle surgeons and there are no standard guidelines. To analyze trends in foot and ankle tourniquet use, the authors conducted an e-mail survey. One thousand six hundred sixty-five foot and ankle surgeons were sent a tourniquet-use survey via e-mail, across Canada and the United States.

Tourniquet safety in lower leg applications.

Purpose: To reduce the chance of injury due to pneumatic tourniquet use, the minimum cuff pressure required to maintain a bloodless field should be used. The purpose of this study was to find out if Limb Occlusion Pressure (LOP--the cuff pressure required to occlude arterial flow) is lower with a wide contoured cuff than with a standard width cylindrical cuff at the calf, if cuff pressures based on measured LOP will be lower than the typical 250 mmHg used in lower leg cuffs, and if a new automatic LOP measurement method gives the same results as the standard Doppler stethoscope method.

Sample: 16 adult volunteers were tested in a controlled laboratory setting, and 53 clinical cases were reviewed at two centers.