optimal timing of intercostal nerve blocks during video-assisted thoracic surgeries

Conditions: Video-Assisted Thoracic Surgery; Video-Assisted Thoracoscopic Surgery

Summary: intercostal nerve block, performed under the guidance of videoscope, is a part of standard anesthesia procedures for patients receiving video-assisted thoracic surgeries. in this double-blind, prospective, multi-center, randomized, controlled clinical trial the investigators aim to compare preemptive versus post-closure intercostal injection of ropivacaine in controlling post-video-assisted thoracotomy pain.

the design of the study is a double-blind, prospective, multi-center, randomized, controlled clinical trial of preemptive vs. post-closure intercostal injection of ropivacaine in controlling post-video-assisted thoracotomy (vats) pain. in standard intercostal nerve block procedures, the contents of a (a total of a 10 ml-solution that consists of 9 ml of ropivacaine hcl 0.5% and 1 ml of dexamethasone 4mg/ml preparation) and c (a total 25 ml solution that consists of 24 ml of ropivacaine hcl 0.5%, 1 ml of dexamethasone-4mg/ml preparation, and 0.125 ml of epinephrine-1:1000 preparation) are combined into one set of injections injected into the intercostal spaces of t5-6, t6-7, t7-8, t8-9 and t9-10, with each intercostal spaces receives about 7 ml of combined a and c solutions (each intercostal space receives 2 ml of a and about 5 ml of c). in this study, the intercostal nerve block is split into two sets of injections: one set of injections at the beginning of vats, and the other set right before closure. therefore the investigators consider both sets of injections as research procedures. patients will be randomly assigned to receive a preemptive 2ml-injection of a or injection of b (contains 10 ml of 0.9% normal saline) at each intercostal space as previously delineated by the operating surgeon. both the research team and the surgical team will be blind to the nature of the injectates during surgery. as parts of the standard care procedures, all patients will be monitored with non-invasive asa standard in addition to invasive arterial blood pressure monitoring. prior to the closure, patients who receive injections of a at the beginning of surgery will receive the second set of injections containing a mixture of b and c (5 ml of solution c is given at each intercostal space) at the intercostal spaces as previously delineated. patients who receive injections of b at the beginning of surgery will receive the second set of injections containing a mixture of a and c (5 ml of solution c is given at each intercostal space). the investigators will group the patients who are assigned to receive injectate a at the end of the surgery as the control group. because the injectate a and injectate c are usually given together in one set of injections at the same anatomical locations in standard intercostal nerve block procedures, the intercostal block received by the control group will closely resemble the procedures performed in standard intercostal nerve block. patients who receive injectate a at the beginning of surgery are grouped as experimental group. regardless of the group assignment, the total dosage of ropivacaine and dexamethasone given to a patient will be equal to the dosage given under the standard care procedures. post operative pain, ventilatory profile and length of hospital stay will be compared between two study arms.

Eligibility criteria:
inclusion criteria: patients will be eligible to enroll in this study if they: * have physical status within asa class ii or iii * are between 18 and 85 years of age * are candidates for vats * are able to complete vas assessments * are competent to sign the informed consent form exclusion criteria: patients will not be enrolled in this study if they: * are pregnant * have allergy to ropivacaine or hydromorphone * have renal insufficiency (egfr\<60ml/min/1.73m2) * have hepatic insufficiency (ast, alt, or both \>60 u/l) or cirrhosis * have a predicted postoperative forced vital capacity (fvc) of \<40%, predicted forced expiratory volume at 1s (fev1) \<40% * have coagulopathy (platelet count\ 2, or both) * have a history of opioid addiction, chronically taking opioids, currently taking high dose of opioids or currently taking opioid agonist+antagonist (e.g. suboxone®) * are taking nonsteroidal anti-inflammatory drug, including aspirin, within a week prior to surgery (since the analgesic effects of nsaid drugs may become confounding factors).