Thoracic Paravertebral Block in Pain Management After Renal Surgery

Objective: The objective of the study was to assess the usefulness of ThPVB in postoperative pain management after open renal resection surgery.

Design, setting, participants: It was a prospective, randomised, open label study held in a university hospital between 08.2013-12.2014. 58 Patients enrolled in the study were scheduled for elective open renal surgery (open nephrectomy or open nephron-sparing surgery) and randomised into two groups - group PVB (n=27) and group GEN (n=31).

Interventions: PVB group received preoperative ThPVB with 0,5% bupivacaine followed by general anaesthesia. GEN group received standard general anaesthesia. Both groups were treated postoperatively with oxycodone IV PCA (patient controlled analgesia) combined with non-opioid analgesics as rescue drugs. The investigators recorded pain severity in VAS, oxycodone requirement in time points, total oxycodone requirement, and sedation levels throughout the first 48h. The investigators measured opioid related adverse events 24 and 48 h postoperatively and patients satisfaction 48h postoperatively.

In PVB group before the induction of general anaesthesia a single shot thoracic paravertebral blockade was performed. ThPVB was performed on Th7-Th10 level, approximately 2,5 - 3 cm lateral from the top of the spinous process with prior ultrasound control of the depth of the transverse process and the pleura. To make the procedure safer the investigators used peripheral nerve stimulation with an isolated 10 cm needle with a start current of 2,5 mA. The needle was inserted until visible muscle activity from intercostal muscles appeared, with a current of 0,5-0,3mA (paravertebral space identification). Next 0,3 ml kg-1 0,5% plain bupivacaine was injected after negative aspiration for air and blood. The efficacy of the blockade was checked after 20 minutes with cold saline.

In both groups, PVB and GEN general anaesthesia was induced with midazolam 0,1 mgkg-1, propofol 2 mgkg-1, cis-atracurium 0,15 mgkg-1 and fentanyl 1,5 µgkg-1. Patients were intubated with a standard single lumen tracheal tube. Anaesthesia was maintained with 1 MAC (Minimal Alveolar Concentration) sevoflurane. For surgical analgesia the investigators used fractional doses of fentanyl 1-3 mg kg-1 if HR (heart rate) or MBP (mean blood pressure) raised above 20% of basal values. Waking up from anaesthesia was in a post-anaesthesia care unit.

Postoperative pain management schedule was identical in both groups. After the surgery, if pain appeared, the patient was given oxycodone i.v. titrated to achieve acceptable analgesia level or until side effects appeared. Every patient received a PCA (Patient controlled analgesia) device with a 1 mgml-1 concentration oxycodone solution with a programmed single bolus dose of 1 mg and a lockout time of 5 minutes. Additionally, patients were given 1g i.v. paracetamol every 6 hours and 100 mg of i.v. ketoprofen every 12 hours.

For 48 h postoperatively, the investigators monitored HR, SBP (systolic blood pressure) , DBP (diastolic blood pressure), sedation level in Ramsay scale, pain intensity at rest in VAS (visual analogue score) scale, oxycodone requirement in pre-selected time points and total oxycodone requirement. The investigators also recorded opioid-related adverse events 24 and 48 h postoperatively in OBAS scale and patients' satisfaction regarding postoperative analgesia 48 h postoperatively in Likert scale.

Eligibility Criteria:
Inclusion criteria:

* Age 18-75
* Scheduled for elective open nephrectomy or NSS
* Gave written consent
* BMI 19-30
* ASA status I-III

Exclusion criteria:

* Presence of chronic pain
* Chronic mental conditions (depression)
* Contraindications for PVB
* Chest or spine deformations
* Infection in planned site of PVB
* Allergies for drugs used in the study
* Cancer invading chest wall