Last updated on March 2019

Paravertebral Block vs. General Anesthesia for Major Abdominal Surgery


Brief description of study

Elderly patients are usually presented with higher risk for developing cardiopulmonary complications after general anesthesia (GA). Bilateral paravertebral block (PVB) has been associated with favorable outcomes in patients undergoing ventral hernia repair. Hence, elderly patients undergoing major abdominal surgery may benefit from PVB anesthetic technique.

Detailed Study Description

Introduction

Elderly patients are usually presented with higher risk for developing cardiopulmonary complications after general anesthesia (GA). The risk of adverse events in elderly patients increases with the combination of intraoperative fentanyl, opioid premedication and neuromuscular blockers. Bilateral paravertebral block (PVB) has been associated with favorable outcomes in patients undergoing ventral hernia repair. Hence, elderly patients may benefit from PVB anesthetic technique.

The objective of the study is to compare PVB versus GA for elderly patients undergoing major abdominal surgery. The primary outcome measure is admission to the Intensive Care Unit (ICU). The secondary objective is postoperative analgesic consumption.

Methods

Following approval from the Institutional Review Board, 40 patients aged 70 years or older scheduled to undergo major abdominal surgery from September 2015 till September 2016 will be included in the study. Consent will be obtained from the patients or their family member. The sealed envelope technique will be used to randomly allocate the patients into two groups. Group I will receive PVB while group II will receive GA.

Demographic variables including age, gender, height, weight, and ASA physical status will be collected for each patient. Intraoperative hemodynamic data such as mean arterial pressure (MAP) and heart rate (HR) are noted pre and post skin incision, during the operation, upon wound closure and at arrival to the Post Anesthesia Care Unit (PACU). Moreover, surgery duration, admission to ICU and hospital stay are recorded.

Pain will be measured using the numeric rating scale (NRS) (0- no pain and 10-maximum possible pain) and will be noted at different time intervals (0, 6, 12, 24, 36 and 48 hours) in addition to analgesic consumption. Morbidity and mortality rates will also be obtained.

General Anesthesia technique Anesthesia is induced with 1 g/kg fentanyl, 1.5-2 mg/kg propofol and 1-2 mg midazolam. Then, endotracheal intubation is facilitated by 0.15 mg nimbex. Anesthesia is maintained by 1-1.5% sevoflurane, 0.5 g/kg/h fentanyl, 0.05 mg/kg/h nimbex, 60% nitrous oxide and 40% oxygen. Any hemodynamic change of 25% results in a gradual increase or decrease of the sevoflurane concentration.

Paravertebral Block Technique Bilateral nerve stimulator-guided PVB is performed while patients are in lateral decubitis position. The number and level of injections depend on the type of surgery and length of incision.

The appropriate levels for the PVBs are determined by palpation of the spinous processes. An intervertebral line is drawn at the appropriate levels and the injection site is marked 2.5 cm lateral to the midline on both sides. After aseptic preparation of the skin, 0.3 mL 2% lidocaine is infiltrated at the injection sites. A 22-G nerve stimulation needle (Stimuplex; B. Braun, Melsungen, Germany) is advanced 1-2 cm perpendicularly to the skin using a nerve stimulating current of 2.5-5.0 mA, while closely watching for contractions of the abdominal muscles. The tip of the needle is adjusted to continue to produce muscle contractions while reducing the stimulating current to approximately 0.5-0.6 mA.

Depending on patient weight, 3-5 mL of the local anaesthetic mixture is injected at each injection site. Each 20 mL of the local anaesthetic mixture contains: 8mL lidocaine 2%, 8 mL lidocaine 2% with epinephrine 5g mL-1, and 4 mL bupivacaine 0.5%.

In case of PVB failure, patients will be converted to GA.

Data collection Residents and trained nurses unaware of the patient's group will be responsible for data collection after the operation. The surgeons and anesthetists who performed the operation will be kept away from data collection and will not be responsible for any further decision.

Postoperative pain management Patients with a pain score between three and four are given Tramadol Hydrochloride (Tramal retard, Grunenthal, Germany) 50-100 mg every 4- 6 hours. If the VAS score is greater or equal to five, patients receive 1 mg/kg Dolosal with a maximum dose of 100 mg (Pethidine Renaudin, Laboratoire Renaudin, France).

Admission to ICU and hospital stay Patients who are hemodynamically stable, conscious and do not feel pain will be transferred from the PACU to the floor. On the other hand, patients will be admitted to ICU if they are unconscious, intubated, and hemodynamically unstable. Patients will be discharged from hospital when they are able to drink, eat and do not have complications.

Morbidity and complications Morbidity is defined as having chest infection, kidney failure, myocardial infarction, and dementia.

Clinical Study Identifier: NCT02534012

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