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Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center at Dallas, Texas
Address correspondence and reprint requests to Dr. Paul F. White, Professor and Holder of the Margaret Milam McDermott Distinguished Chair, Department of Anesthesiology and Pain Management, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9068. Address e-mail to paul.white{at}utsouthwestern.edu.
In this issue of Anesthesia & Analgesia, Hadzic et al. (1) present the results of a comparative evaluation of paravertebral blocks with propofol sedation and general anesthesia with propofol and desflurane for outpatient inguinal hernia repair. The authors report that paravertebral blocks are associated with a faster recovery and less postoperative pain than general anesthesia involving tracheal intubation and local anesthetic infiltration. While the authors are to be commended for performing a carefully conducted randomized, prospective comparison of two different anesthetic techniques for this commonly performed ambulatory surgery procedure, the study revisits a largely resolved controversy regarding the choice of anesthetic technique for inguinal herniorrhaphy (2,3).
The use of paravertebral blocks in outpatients undergoing herniorrhaphy was initially described in the early 1980s (4). However, the technique failed to gain widespread acceptance. A critical review of the peer-reviewed anesthesia and surgery literature reveals possible explanations. Shortly after their original publication in 1981 (4), Evans et al. (5) described inadvertent intrathecal injection during the performance of a paravertebral block. In the late 1990s, the regional anesthesia group at Duke University (8) published a case series involving the use of paravertebral blocks for superficial ambulatory surgery procedures (e.g., breast surgery, hernia repair) (6–9). In one of their larger series involving women undergoing breast surgery, this group reported a 15% initial failure rate with paravertebral block (although 6% of these cases had successful surgery when supplemented with local anesthetic infiltration) and a 3% incidence of complications. In 22 patients who received paravertebral block for outpatient inguinal herniorrhaphy, Klein et al. (9) failed to achieve successful surgical analgesia in 9% of the cases. Furthermore, adequate surgical conditions were not achieved until 15–30 min after the paravertebral block was completed.
In a small series of patients undergoing inguinal herniorrhaphy with either paravertebral blocks or a local field block, Wassef et al. (10) reported that the paravertebral block group required significantly less local anesthetic and fewer needle insertions and was associated with a "significantly higher success rate than a field block." In a comparison of paravertebral block and general anesthesia for breast surgery, Pusch et al. (11) reported that paravertebral block was a suitable alternative to general anesthesia. However, the block failed to provide adequate surgical analgesia in 7% of the cases, and one patient experienced epidural spread with parathesias and a Horner’s triad. In a similar comparison with general anesthesia, Klein et al. (12) suggested that the use of paravertebral blocks provided longer lasting pain relief with few postoperative side effects. In nonrandomized comparisons of paravertebral block with general or spinal anesthesia for hernia surgery (13,14), Naja et al. reported that paravertebral block was associated with a shorter hospital stay, improved analgesia and less postoperative nausea and vomiting. Importantly, the length of the hospital stay ranged from 1 to 4 days in these studies.
Although paravertebral block provides better postoperative pain relief than general anesthesia immediately after surgery (15), Terheggen et al. concluded that the risk:benefit ratio favors general anesthesia over paravertebral block. In this small series of patients undergoing minor breast surgery (n = 15), one patient experienced an inadvertent epidural block and another had a pleural puncture. In describing their clinical experience with paravertebral block in patients undergoing inguinal hernia repair, Weltz et al. (16) reported failure of paravertebral block to provide adequate surgical anesthesia in 20% of the cases and reported potentially serious complications (e.g., epidural extension) in 7% of the patients. Although 96% of the patients were able to be discharged after "an average stay of 2.5 h," 4% had to be admitted to the hospital. Another research group also reported a 2% complication rate in the paravertebral blocks for breast surgery (17). Although it is possible that the use of this technique may be justified in selected patients with significant comorbid conditions (18,19), the risk:benefit ratio seems unacceptably high for patients undergoing a simple operation for which similar and safer local anesthetic–based technique appear to provide similar outcomes (2,20,21). In a comparison of paravertebral block with an intraoperative peripheral block performed by the surgeon for hernia surgery, Klein et al. (20) reported that paravertebral block produced "equivalent analgesia" with the local tissue infiltration technique.
Hadzic et al. have extensive experience in the performance of these blocks and reported no major complications with paravertebral block in their small series (n = 25). Nevertheless, the time required to perform the paravertebral block was significantly longer than to induce general anesthesia (and presumably to start the operation). However, the major concern with this otherwise well conducted clinical study relates to the choice of a nonstandard general anesthetic "comparator" group. As suggested in earlier prospective, randomized comparative studies, a peripheral nerve block (e.g., ilioinguinal-iliohypogastric nerve block) supplemented with local anesthetic infiltration provides superior outcomes compared with general endotracheal and spinal anesthesia (2,21,22). If one is going to compare a regional anesthetic technique to general anesthesia for a superficial surgical procedure (e.g., hernia repair or breast surgery), tracheal intubation should be avoided, because these cases are most commonly performed using a laryngeal mask airway (LMA) for airway management (23), obviating the need for both muscle relaxant and reversal drugs.
Another concern is the fact that the percentage of patients achieving fast-track eligibility in the study by Hadzic et al. (1) was very small (i.e., only 8% for general anesthesia and 71% for paravertebral block). In a study involving a similar outpatient surgery population, Tang et al. (24) achieved 100% fast-track eligibility and an average time to discharge home of only 46 min using similar general anesthetic drugs with a LMA and local anesthetic infiltration. In contrast, the average time to ambulation was 102 min in the paravertebral block group (1). In a study involving general endotracheal anesthesia for outpatient laparoscopic gynecologic surgery, Coloma et al. (25) were able to fast-track 80% of these cases with an average time to home readiness of 120 min. Song et al. (2) achieved times to home readiness after monitored anesthesia care with IV sedation and general endotracheal anesthesia for inguinal herniorrhaphy of 133 and 171 min, respectively, at a public teaching hospital. In the present study, average times to home readiness and actual discharge after paravertebral block were 156 and 179 min, respectively. The question of whether regional anesthesia is really better than a well conducted general anesthesia (or sedation techniques) remains unclear, since the comparative studies of anesthetic techniques are inherently biased due to a lack of blinding (26).
Although peripheral nerve blocks are invaluable for ambulatory surgery, both as "stand alone" techniques, as well as part of sedation or general anesthetic techniques (27,28), this study failed to establish the added value of paravertebral block for routine inguinal hernia repair in the ambulatory setting. Hopefully, these investigators will consider performing a carefully controlled, prospectively randomized comparison of their paravertebral block technique to a more clinically relevant anesthetic technique (e.g., ilioinguinal-iliohypogastric nerve block with local anesthetic infiltration (21,22) as part of a sedation or general anesthetic technique with a LMA device). As acknowledged by Hadzic et al. (1), their study was not adequately powered to determine the potential impact of paravertebral block on anesthesia control time or the risk of serious complications (e.g., pneumothorax).
In evaluating recovery times and other clinically meaningful recovery end points, it is unclear if the use of a more complicated peripheral nerve block technique (i.e., paravertebral block versus ilioinguinal/iliohypogastric) represents a clinically meaningful advance in anesthesia for outpatient herniorrhaphy. In attempting to develop a better regional anesthetic technique for a simple operation like inguinal hernia repair, better may be the enemy of good!
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Accepted for publication January 24, 2006.
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This article has been cited by other articles:
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  P. F. White, H. Kehlet, J. M. Neal, T. Schricker, D. B. Carr, F. Carli, and the Fast-Track Surgery Study Group The Role of the Anesthesiologist in Fast-Track Surgery: From Multimodal Analgesia to Perioperative Medical Care Anesth. Analg., June 1, 2007; 104(6): 1380 - 1396. [Abstract] [Full Text] [PDF]
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R. K. Baumgarten, R. A. Greengrass, and C. A. Wesen Paravertebral Block: The Holy Grail of Anesthesia for Hernia Surgery? Anesth. Analg., January 1, 2007; 104(1): 207 - 207. [Full Text] [PDF]
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P. F. White Paravertebral Block: The Holy Grail of Anesthesia for Hernia Surgery? Anesth. Analg., January 1, 2007; 104(1): 208 - 209. [Full Text] [PDF]
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A. Hadzic, K. Beklen, P. E. Karaca, and R. E. Claudio Paravertebral Block: The Holy Grail of Anesthesia for Hernia Surgery? Anesth. Analg., January 1, 2007; 104(1): 207 - 208. [Full Text] [PDF]
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