ORIGINAL ARTICLE – THORACIC
Interactive CardioVascular and Thoracic Surgery 20 (2015) 296–299 doi:10.1093/icvts/ivu395 Advance Access publication 23 November 2014
The importance of pleural integrity for effective and safe thoracic paravertebral block: a retrospective comparative study on postoperative pain control by paravertebral block Teruya Komatsua,*, Terumasa Sowaa, Atsunari Kinob and Takuji Fujinagac a b c
Department of General Thoracic Surgery, Kyoto University Hospital, Kyoto, Japan Department of Anesthesiology, Nagara Medical Center, Gifu, Japan Department of General Thoracic Surgery, Nagara Medical Center, Gifu, Japan
* Corresponding author. Department of Thoracic Surgery, Kyoto University Hospital, 54 Kawaharacho, Shogoin, Sakyo-ku Kyoto 606-8507, Japan. Tel: +81-75-7514975; fax: +81-75-7514974; e-mail:
[email protected] (T. Komatsu). Received 18 July 2014; received in revised form 23 October 2014; accepted 3 November 2014
Abstract OBJECTIVES: Recently, paravertebral block (PVB) has been reported to be an effective analgesic modality for post-thoracotomy pain, but there is no consensus on how thoracic PVB can be more effective. Our hypothesis that intact pleura has a significant impact on the analgesic effectiveness of thoracic PVB was evaluated. METHODS: Data of patients who underwent general thoracic surgery [thoracotomy or video-assisted thoracic surgery (VATS)] and paravertebral catheterization at Nagara Medical Center between April 2010 and March 2013 were collected. To compare the frequency of nonsteroidal anti-inflammatory drugs taken as well as the usage of rescue pain medications between patients with pleural disruption and those without, data were analysed after matching on propensity scores. Covariates for match estimation were age, sex, body mass index, American Society of Anesthesiologists score, diagnosis, operative details and local anaesthesia infused. RESULTS: There were 278 patients who underwent general thoracic surgery and paravertebral catheterization. The propensity scorematching process created 78 matched patients with pleural disruption and those without. Based on the propensity score matching, a significant increase in the frequency of non-steroidal anti-inflammatory drugs taken on postoperative day 1 and in the usage of rescue drugs was observed in patients with pleural disruption. CONCLUSIONS: According to our analysis, creating a sub-pleural space without pleural disruption is essential for quality thoracic PVB. Keywords: Paravertebral block • Pleural disruption • Thoracic analgesia • Postoperative pain management
INTRODUCTION
MATERIALS AND METHODS
Post-thoracotomy pain, which is encountered frequently, can lead to a high incidence of pulmonary complications if it is not controlled appropriately [1]. Presently, several analgesic techniques are used to control post-thoracotomy pain; among these techniques, epidural block is the most common and is the gold standard [2, 3]. We introduced paravertebral block (PVB) for thoracic analgesia in April 2010 at our institution because of its simplicity and analgesic effectiveness [4]. Thoracic PVB was originally described by Sabanathan et al. [5, 6], and they subsequently updated this technique by inserting an indwelling extrapleural catheter for continuous infusion of local anaesthetic (LA) postoperatively. The analgesic effectiveness of thoracic PVB has been validated by several studies [7–11]. We conducted a retrospective analysis to prove our hypothesis that pleural integrity should be maintained during PVB catheterization for more effective thoracic analgesia.
This study included patients who underwent general thoracic procedures for pulmonary and mediastinal lesions and subsequent PVB catheterization between April 2010 and March 2013. The study was approved by the Institutional Review Board (IRB) of Nagara Medical Center and the IRB waived the need for written consent from the patients. The confidentiality of information created as part of the data collection was strictly maintained.
Technique of paravertebral block catheter insertion An indwelling extrapleural catheter (a commercially available 18-gauge epidural catheter) is placed just before initiating the closure of each incision. The PVB catheter is placed so that the
© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
T. Komatsu et al. / Interactive CardioVascular and Thoracic Surgery
Propensity score matching Prematch baseline characteristics were compared by bivariate analysis to assess imbalances of covariates. As an observational study, the occurrence of pleural disruption during PVB catheterization was not random since each surgeon tried to maintain pleural integrity. The pleural disruption (+) group and the (−) group may differ in variables that influence degree of analgesia. In an attempt to reduce the effect of potential bias, propensity score matching was used. Propensity scores were calculated by logistic regression analysis including the occurrence of pleural disruption as the response variable, and age, sex, body mass index (BMI), American Society of Anesthesiologists (ASAs) score, diagnoses, operative procedures including approach [ postero-lateral thoracotomy, anterior axillary thoracotomy or video-assisted thoracic surgery (VATS)], and intra-operative bleeding, operative time and local anaesthesia infused as explanatory variables. The estimated propensity score was then used to match 1:1 patients with similar propensity. These data were collected retrospectively based on the chart review. Continuous variables are expressed as the mean (standard deviation). To assess the patients’ demographic and perioperative variables, the χ 2 test with Yates’ correction, when appropriate, was applied to compare the distributions of discrete variables, and the Student’s t-test was used to compare metric variables. All tests were two-sided, and P-values
