Authors (including presenting author) :
Wong HMK(1), Mok LYH(1), Chen PY(1), Au SSW(1), Wong RHL(2)
Affiliation :
(1) Department of Anaesthesia and Intensive Care, Prince of Wales Hospital, The Chinese University of Hong Kong, (2) Department of Cardiothoracic Surgery, Department of Surgery, The Chinese University of Hong Kong
Introduction :
Sternotomy pain is usually significant after cardiac surgery. Analgesic options for sternotomy in cardiac surgery are often limited. Poorly controlled acute pain is an important factor to development of chronic postsurgical pain. The reported incidence ranges from 28% to 56% up to 2 years postoperatively. The transversus thoracis muscle plane (TTP) block is a novel technique that provides analgesia to anterior chest wall. A pilot study was conducted to assess the feasibility of applying TTP block as an adjunct to analgesia in cardiac surgery
Objectives :
(1) To assess the feasibility of applying TTP block as an adjunct to analgesia in cardiac surgery
(2) To provide the basis for sample size calculation and power analysis for a larger-scale randomized controlled trial
Methodology :
In this single-blinded, prospective, randomized controlled pilot study, patients aged 18 or older, undergoing elective cardiac surgery were randomized to intervention or control group on the day of admission for operation. Under ultrasound guidance, intervention group received bilateral TTP block, 20ml 0.25% levobupivacaine per side, after induction of general anaesthesia. Another 4ml 0.5% levobupivacaine was injected subcutaneously over the clavicular heads to block medial branch of supraclavicular nerves that provide sensory innervation to upper chest. Control group did not receive any injections. All blocks were performed by a single blinded anaesthetist and data was collected by blinded assessors. Primary outcomes are the rate of recruitment and adverse events. Secondary outcomes include intraoperative and postoperative opioid consumption, hemodynamic changes with sternotomy, Visual Analogue Scale (VAS) pain score at rest and upon 3 maximal coughs at 12, 24, 48 and 72-hour postoperatively, time to extubation, length of ICU and hospital stay.
Hemodynamic changes with sternotomy are defined as the percentage (%) changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR) between the baseline and their peaks within 10 minutes of skin incision. The baseline blood pressure is captured upon resting the patient for 5 minutes prior to skin incision.
Result & Outcome :
Results
24 patients were recruited with 12 in each group. The recruitment rate was 100% and there was no block-related adverse event. The mean (SD) %SBP, MAP, DBP change at incision were 13.5% (8.7), 12.6% (8.4), 13.2% (9.9) in block group vs 35.8% (16.9), 36.5% (16.1), 32.1% (14.6) in control group (p=0.001, p< 0.001, p=0.001 respectively). The mean (SD) intraoperative opioid consumption (morphine equivalent) was 7.6mg (3.6) vs 17.4mg (6.1) in block and control group respectively (p< 0.001). The mean (SD) VAS pain score at rest within 72 hours after surgery was 6.5 (5.5) vs 6.5 (4.9) in block and control group. The mean (SD) VAS pain score upon 3 maximal coughs within 72 hours was 17.0 (7.3) and 20.6 (9.6) in block and control group. Mean (SD) extubation time was 6.8 (3.9) hours vs 7.2 (3.7) hours in block and control group. Mean (SD) ICU stay was 21.5 (2.3) hours vs 19.8 (5.3) hours and mean (SD) hospital stay was 8.9 (2.3) days vs 9.7 (2.3) days in block and control group, respectively.
Conclusion
TTP block is a novel technique for sternotomy pain management. The study shows TTP block is reliable and may associate with stable hemodynamic at incision with intraoperative opioid-sparing effect, which has significant implication to the development of ultra-fast-track cardiac anaesthesia. The pilot study also provides basis for a larger-scale randomized controlled trial to evaluate the analgesic efficacy of TTP block for sternotomy in cardiac surgery.
