Sequential compression alone for the prevention of deep venous thrombosis in operating theatres

This is a prospective point prevalence, surgical comparative effectiveness study of patients undergoing either an emergency or elective laparoscopic cholecystectomy. It is a requirement of the study that any participating hospital has already adopted or is trialing the protocol of routine Sequential Calf Compression Devices (SCCDs) alone for laparoscopic cholecystectomy prior to data collection, and that this decision is made on clinical grounds and not for the purposes of research. All patients requiring either an elective or an emergency laparoscopic cholecystectomy will be recruited into this study. For those participants who are booked for an elective laparoscopic cholecystectomy, they will be admitted to the hospital on the day of their surgery. A sequential calf compressor device will be fitted as per manufacturer’s specifications by the trained theatre technician, immediately prior to the commencement of surgery and will be used for the duration of surgery (approximately 1 hour), performed by or under the supervision of a consultant general surgeon. At the completion of surgery and immediately before the patient is transferred to the post anaesthetic care unit (PACU), the SCCDs will be removed. Chemical thromboprophylaxis will be initiated by the subcutaneous injection of 40 mg of enoxaparin, 5,000 IU of dalteparin or 5,000 IU of heparin at any time at the discretion of the treating team. Subsequent does of enoxaparin and dalteparin (if required) are given 24 hours later following the initial dose. The dosing of enoxaparin is to be based on BMI and renal function only. For those patients whose Body Mass Index (BMI) is less than 40, use 40 mg once daily (OD), for those patients whose BMI is equal to or greater than 40, use 40 mg twice daily, with the second dose being given 12 hours after the initial dose. For those patients with chronic renal disease, with a creatinine clearance of less than 30 mL/minute, a renal adjusted dose will be given. For those patients receiving heparin, the second dose will be given 12 hours post the initial dose. No participant undergoing an elective operation is to have Graduated Compression Stockings (GCSs) fitted either pre- or post-operatively. Participants may be discharged home on the day of their surgery, or after an overnight hospital stay, at the discretion of their treating surgeon. During the operation, positioning of the patient and the intra-abdominal insufflation pressure will be at the discretion of the treating surgeon. For those participants who are undergoing an emergency laparoscopic cholecystectomy, access to theatre may differ across the various hospital campuses. This will be controlled for by the acquisition of data pertaining to the length of time of admission to the hospital, relative to the timing of their actual surgery. For these patients, it is anticipated that they will have received chemical thromboprophylaxis prior to their operation. This data will be collected and analysed separately as a sub-analysis. There will be no restrictions on the type and timing of chemical thromboprophylaxis used. These patients are allowed to have GCSs fitted pre-operatively. However, these GCSs will be removed when the patient presents to the operating theatre and the use of GCSs post-operatively is contraindicated. SCCDs will be applied as per the manufacturer's instructions by the trained theatre technician. The operation will be performed or supervised by a consultant general surgeon. Demographic and operative data will be collected at the end of the operation by the surgical fellow/registrar/resident who has been recruited to the study and trained under the auspices of the WestSURG collaborative. This process will also be supervised by the PI from each institution. All participants may be seen post-operatively in surgical outpatient clinics at the discretion of the treating surgeons. This clinic appointment may be face to face, or conducted via telephone or telehealth. At this visit, symptoms of Venous Thromboembolism (VTE) may be enquired about, and if suggestive of a VTE, image confirmation may be obtained. As part of this study, all patients will be contacted between day 30 and 35 post-operatively via telephone to enquire about symptoms that may be suggestive of the development of VTE, irrespective of the clinical follow-up. Post-operative morbidity will also be sought via this phone process, as well as review of the patient's file. The process of the phone questionnaire will include a verbal consent. This process will occupy approximately 2 – 5 minutes of their time and involves a fixed set of questions that are verbally asked for each participant regarding any morbidity or symptoms of VTE with results recorded by the researcher straight on to a REDCap database. For those participants who have symptoms suggestive of a VTE, they will be referred back to their treating hospital via the Emergency Department for image confirmation of VTE which may include bilateral leg ultrasound if experiencing symptoms of deep venous thrombosis, or computed tomography pulmonary angiogram if experiencing symptoms of pulmonary embolism. If VTE is confirmed, then an anticoagulation regime will be commenced at the discretion of the clinical team, the duration of which is guided by the latest guidelines from the Thrombosis and Haemostasis Society of Australia and New Zealand (Tran et al., 2019).