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Original Article

Prostate anaesthetic block with ropivacaine for urologic surgery

Niccolai, P.1; Carles, M.2; Lagha, K.3; Raucoules-Aimé, M.2

Author Information
European Journal of Anaesthesiology: November 2005 - Volume 22 - Issue 11 - p 864-869
doi: 10.1017/S0265021505001468

Abstract

Introduction

Prostate anaesthetic block for transurethral surgery, described in 1996 by Tabet and Levine, provided adequate anaesthesia in patients at high risk for spinal or general anaesthesia [1]. However, that pilot study has several limitations: it was not comparative and the benefit in terms of haemodynamic repercussions was not evaluated, particularly versus spinal anaesthesia. Pertinently, this latter point is important because those authors recommend the technique for elderly fragile patients for whom episodes of hypotension or tachycardia can be deleterious [2,3]. In addition, they used lidocaine, whose duration of action is brief, and did not report on postoperative pain. Ropivacaine is now widely used for peripheral anaesthetic blocks and could, because of its longer duration of action and its safety, be indicated in this setting. Our objective was to evaluate, by comparison with spinal anaesthesia, prostate anaesthetic block using ropivacaine for haemodynamic tolerance, quality of analgesia during and after surgery.

Methods

This prospective study was approved by our Institutional Review Board for human investigation (Comité Consultatif de Protection des Personnes dans la Recherche Biomédicale, Nice) and written informed consent was obtained from each patient. By randomization, 90 adult males, ASA III/IV, scheduled to undergo transurethral surgery (bladder tumour, bladder-neck resection, prostate resection with prostate weight estimated by endorectal ultrasonography to be <30 g, urethral stent) with no contraindications or no objection to local anaesthesia, were eligible for the study. Patients were excluded when they were: febrile, had recently used opioids or any analgesic drug, or were unable to use the visual analogue scale (VAS) for pain assessment. Preoperative haematological analyses included haemoglobin, platelet count, electrolytes, coagulation time and prothrombin time. Angiotensin-converting enzyme inhibitors had been withdrawn 24 h before the intervention but beta-blockers and calcium-channel blockers were continued until surgery. Low-dose aspirin therapy was discontinued at least 10 days before surgery.

All patients were premedicated with oral hydroxyzine hydrochloride (50 mg 1 h preoperatively). The same anaesthetist administered all anaesthetic products. The same surgeon performed all interventions using a standardized procedure. On arrival in the operative room, automatic non-invasive blood pressure (BP) and electrocardiograph monitoring were started. Systolic (SBP), mean (MBP) and diastolic (DBP) blood pressures were measured on three successive occasions on arrival in the induction room to establish baseline levels, at 3-min intervals until 30 min after anaesthesia induction and at 5-min intervals during surgery, every 15 min in the recovery room and at 4-h intervals during the first 24 h after the end of surgery. Heart rate (HR) and oxygen saturation were recorded from continuous electrocardiography and pulse oximetry.

Patients were randomly assigned to receive prostate anaesthetic block or spinal anaesthesia. Patients receiving the prostate anaesthetic block (n = 45) were placed in the dorso-lithotomy position. Ten millilitres of 2% lidocaine jelly were instilled in the urethra before the block. After cutaneous anaesthesia (1% lidocaine, 5 mL) 1 cm above the pubis, a 22-G spinal needle was inserted into the retropubic space. The needle was directed towards the base of the prostate using the index finger in the rectum as a guide. The tip of the needle should be palpated across the rectum wall as it goes beyond the thick endopelvic fascia. Ropivacaine (7.5 mg mL−1, Naropeine®; Astra-Zeneca, Paris, France) was injected (8-10 mL to each site) into four sites: at the base, the apex and each side of the prostate for a total of 225-300 mg. Surgery could be initiated 10 min later.

Before administration of spinal anaesthesia to the other patients (n = 45), 500 mL of Hartmann's solution was given intravenously (i.v.). Spinal anaesthesia was performed using 2.5 mL 0.5% hyperbaric bupivacaine (12.5 mg, Marcaine®; Astra-Zeneca, Paris, France) administered through a 24-G Sprotte needle at the L3-L4 or L2-L3 interspace via a midline approach, with the patient in sitting position. The solution was injected over 30 s, aspirating once to check free flow of cerebrospinal fluid. When the sensory level reached T10, patients were placed in the lithotomy position for surgery.

For both patient groups, if SBP was <100 mmHg on two consecutive readings or if indicated on clinical grounds (nausea, vomiting or unusual light-headedness), patients received an infusion of crystalloids (8 mL kg−1) and/or i.v. 6-mg ephedrine bolus. All patients received target-controlled propofol infusion (Diprifusor©; Zeneca, London, UK) with a target concentration of 1-1.5 μg mL−1, and adjusted to permit constant verbal contact with the patient and to reduce his anxiety (score of 4 or more on the observer's assessment of alertness/sedation (OAA/S) scale) [4]. Oxygen was supplied by mask and a single dose of cefazolin (2 g) antibiotic prophylaxis was given. A suprapubic catheter was routinely inserted after the procedure.

Pain was assessed using a visual analogue pain score (0-100 mm) and discomfort was graded 0 (none)-3 (intense). A nurse trained in pain assessment was assigned to question patients, until return to their rooms, as follows: before, during and immediately after the block, every 10 min during surgery, admission to the recovery room, just before discharge; questioning was pursued by ward nurses every 4 h for the first 24 h. General anaesthesia was administered when the patient's pain score was ≥40 mm or discomfort grade was >2 during surgery. Postoperative pain management was standardized as follows: during the postoperative period, 2 g of propacetamol (Pro-Dafalgan®; UPSA, Paris, France) and 100 mg of ketoprofen (Profenid®; Aventis, Paris, France) were injected i.v. every 6 h and 8 h, respectively, during the first 24 h. On the ward, if the pain score was ≥40 mm, oral morphine (5 mg, Actiskenan®; UPSA, Paris, France) was given. Prophylactic antiemetics were not administered.

The main outcome measurement during anaesthesia, surgery and recovery room was haemodynamic tolerance (number of hypotensive episodes, HR, SBP, and MBP). Hypotension was defined as a 25% decrease from baseline for both SBP and MBP, or an SBP <100 mmHg. Other outcome variables were the pain score and discomfort scale during anaesthesia and surgery, the number of patients requiring general anaesthesia or having clinical signs of local anaesthetic toxicity, pain score at admission to the recovery room before discharge from it and every 4 h until 24 h after the end of surgery and total amount of oral morphine required during the 24-h postoperative period. Nausea, vomiting, antiemetic requirements, other adverse events, OAA/S scale score and respiratory rate were fully recorded. Finally, the next morning, the patient was asked to fill out a special form to assess his experience and to reveal whether he would choose to have the same type of anaesthesia again.

Sample size was calculated as follows: in a previous study, spinal anaesthesia-induced hypotension in 62% of elderly patients who had received 500 mL of crystalloid preload [5]. To detect at least a 50% difference in the hypotension rate, assuming equal numbers of patients per groups with similar characteristics, with an alpha-error of 0.05 and a power of 0.90, 42 subjects had to be included per group.

Statistical analysis

The difference between the two groups for number of hypotension episodes was analysed using the χ2-test. The between-group differences for haemodynamic data and pain scores as a function of time were analysed using two-way analysis of variance for repeated measurements. Student's unpaired t-test was used to assess the between-group differences for haemodynamic data, vascular filling and amount of ephedrine given. Bonferroni's correction was applied when multiple comparisons were made. Results are expressed as means ± SD (range). A P value <0.05 was considered significant.

Results

Characteristics and outcome measurements for patients are reported in Table 1. The two groups were comparable with respect to age, weight, height, ASA physical status and haemodynamic parameters before anaesthesia. Sixty-six patients were ASA III and 24 ASA IV. Ongoing therapies were also comparable: 33 patients were taking beta-blockers (prostate anaesthetic block vs. spinal anaesthesia: 15 vs. 18, respectively), 41 angiotensin-converting enzyme inhibitors (19 vs. 22), 34 calcium-channel blockers (16 vs. 18) and 21 diuretics and/or digoxin (11 vs. 10). All surgical procedures were performed under good conditions for the surgeon and the patients. No patient had to be excluded from the study due to anaesthetic failure.

Table 1
Table 1:
Characteristics and outcome measurements for patients undergoing transurethral surgery with prostate anaesthetic block or spinal anaesthesia.

For patients receiving prostate anaesthetic block, the time for local infiltration was 9.7 min ± 2.4 (range 8-15). BP and HR did not change significantly during nerve-block administration, surgery and the recovery period (Table 1). None required ephedrine or vascular filling. No direct intravascular injection, clinical signs of ropivacaine toxicity or complication were observed. No patient required blood transfusion.

For patients receiving spinal anaesthesia, haemodynamic data are reported in Table 1. The incidence of hypotension was 55.6% (n = 25) compared to zero in the prostate anaesthetic block group (P < 0.001). Twenty-five patients required vascular filling during surgery (mean volume: 750 ± 120 mL). Four patients required additional ephedrine administration and the maximum dose administered to any patient was 27 mg. One patient required blood transfusion for a postoperative haemorrhage.

Discomfort scores (Table 1) and patient acceptance of the anaesthesia technique were similar for both groups (prostate anaesthetic block: 98% vs. spinal anaesthesia: 96%). All patients stated that they would choose the same anaesthesia again. Patients were eating at a mean of 4 h after surgery, with no between-group difference. All pain scores were <40 mm during the anaesthetic procedures and during surgery (Fig. 1); two patients received oral morphine during the postoperative period (at 10 and 12 h) in prostate anaesthetic block group and four who had received spinal anaesthesia (not significant). No patients experienced postoperative vomiting, retching, marked sedation or respiratory depression. Three patients who had received spinal anaesthesia needed treatment for nausea (vs. none in the prostate anaesthetic block group).

Figure 1.
Figure 1.:
Mean (SD) VAS pain data before anaesthesia (baseline) and during the 24 postoperative hours in the two groups. No significant difference was noted.

Discussion

Anaesthesia for urologic procedures is often challenging because of the risk associated with age and ASA status. This surgery is generally performed on a relatively elderly population and is associated with considerable morbidity, particularly attributed to haemodynamic changes during general or spinal anaesthesia. The results of a retrospective study suggested that patients who became hypotensive during anaesthesia had a five-fold higher risk of perioperative myocardial infarction compared with patients with no hypotension [2]. The data obtained for our elderly population with multiple medical risk factors show that adequate anaesthesia and cardiovascular stability were achieved with the prostate anaesthetic block.

Systemic hypotension is the most common complication of spinal anaesthesia, occurring in 25-82% of elderly patients [6-8]. These patients are particularly susceptible to hypotension during spinal anaesthesia because they have a high incidence of co-existing disease. Buggy and colleagues [5] reported 62% spinal anaesthesia-induced hypotension (using the same definition) in the elderly receiving, as in our study, 500 mL of crystalloid preload. This rate is close to that observed here. Preload administration of 500 mL if crystalloid might appear low but infusion of large fluid volumes is dangerous in these patients with cardiac dysfunction [5]. In contrast, BP and HR stabilities were remarkable for patients who had received a prostate anaesthetic block. Indeed, this technique circumvented excess vascular filling and the need for vasoconstrictors, which can expose elderly patients with latent coronary artery disease to myocardial ischaemia [5-9].

There are several limitations to this study. The majority of patients were being treated for cardiovascular diseases and several were taking beta-blockers, which can modify haemodynamic responses to anaesthesia and surgery. But this is indeed the situation for ASA III/IV patients. Nonetheless, the two groups were comparable for ASA status and ongoing medications. Because both groups received continuous administration of low-dose propofol, it can be advanced that pain and comfort scores might be affected. However, the target concentrations used were very low, as demonstrated by the constant verbal contact with the patient throughout the intervention. Because, in our population, the prostates were <30 g, operating time <30 min, the negligible blood loss did not require transfusion and no marked fluid absorption occurred, we cannot speculate as to how the prostate anaesthetic block would behave in circumstances where its alleged benefits would be most needed.

Four anatomic approaches to anaesthetize the prostate locally have been reported [10-14]. The retropubic approach is simple, reproducible and directly follows the neuroanatomy of the prostate. Denonvilliers' fascia, the lateral fascia, the neurovascular bundle and the pelvic plexus form a closed zone, whose architectural characteristics optimize the diffusion of a local anaesthetic injected into the space beyond the endopelvic fascia, rendering unnecessary anaesthesia of the branches of the pudendal nerve and the prostatic plexus at the apex of the prostate. This infiltration achieves nerve block in the region of the prostate and the trigonum of the bladder. Although topical anaesthesia of the distal urethra facilitates endoscopic surgery, in no way is it sufficient alone for this intervention. However, this retropubic approach requires a large volume of anaesthetic to assure sufficient diffusion to the supplying nerve plexus [14]. We did not measure circulating ropivacaine concentrations after obtaining the prostate block but we used the dose recommended for peripheral block: 40 mL of a 0.75% solution for single injections. That means we injected 32-40 mL, a volume comparable to that used in the other perineal approaches [10,11]. Furthermore, considering the large dose of ropivacaine (40 mL of 7.5 mg mL−1) used to produce a reliable block, we can wonder about its general side effects in circumstances where the haemodynamically and surgically challenged, ageing, ASA III/IV body is pushed to the limit by more demanding surgical impact than that encountered in the present trial. In that context, we would be a bit wary of the possibility of intravascular local anaesthetic injection in males with large vascularized prostates with engorged subcapsular veins and grossly distorted anatomy.

This is the first study to analyse the duration of postoperative analgesia with a prostate anaesthetic block. In their study, Tabet and Levine used lidocaine, whose duration of action is short, and focused on the intraoperative period [1]. We chose ropivacaine for our study because of its longer duration of action, and it has a better safety margin than bupivacaine. Postoperative pain in our patients was effectively controlled by ropivacaine combined with non-steroidal anti-inflammatory drugs.

In conclusion, based on the results of this study, prostate surgery under ropivacaine nerve block is haemodynamically safe and assures adequate analgesia during and after surgery. However, the haemodynamic tolerance of the prostate anaesthetic block remains to be evaluated in patients undergoing surgery with large blood loss.

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Keywords:

NERVE BLOCK; prostate; ANAESTHESIA; SPINAL; local ANAESTHETICS LOCAL; ropivacaine; UROLOGIC SURGICAL PROCEDURES; MALE

© 2005 European Society of Anaesthesiology