Surgical placement of rectus sheath catheters in a cadaveric cystectomy model.

Introduction Surgically inserted rectus sheath catheters (RSCs) are used increasingly for analgesia after cystectomy and other abdominal surgery. Currently, there is little information on the optimal positioning of RSCs to allow maximal spread of local anaesthetic. This study sought to assess the spread of dye injected via RSCs and to highlight the extent of its coverage in a fresh unembalmed cadaveric cystectomy model in order to confirm the nerve endings that are likely to be anaesthetised with RSCs. Methods Four cadavers underwent lower midline incision with limited bladder mobilisation. A RSC was inserted into the eight hemiabdomens. The RSCs were positioned either anterior (n=5) or posterior to the rectus muscle (n=3). Dye was injected down the RSCs to evaluate spread. The eight hemiabdomens were dissected anatomically to determine the surface area of dye spread and nerve root involvement. Results The mean surface area of dye spread with anteriorly placed RSCs was 30.6cm2 anterior and 25.9cm2 posterior to the rectus muscle. The mean surface area of dye spread with posteriorly placed RSCs was 11.3cm2 anterior and 37.3cm2 posterior to the rectus muscle. The mean number of nerve roots stained with anteriorly and posteriorly placed RSCs was 3.8 and 2.7 respectively. Subcutaneous spread of dye was seen with one anterior RSC insertion. Peritoneal spread was seen with one anteriorly positioned RSC. Conclusions This study has demonstrated efficient nerve root infiltration with anteriorly and posteriorly positioned RSCs. It appears that dye spreads between the fibres of the rectus muscle rather than out laterally to the nerve roots when spreading from its initial compartment.

Epidural distribution of dye administered via an epidural catheter in a porcine model.

BACKGROUND: Local anaesthetics are commonly delivered to the epidural space by either intermittent bolus or continuous infusion. While these methods have been investigated in terms of analgesia and total dose administered, they have not been compared in terms of their effect on the spread of injectate within the epidural space. This animal study compared the spread of dye delivered to the epidural space in a porcine model by either bolus or infusion. METHODS: After ethical approval, epidural catheters were placed at three vertebral levels in seven anaesthetized pigs. Aqueous dye (1 ml) was injected into the catheter as a bolus, or as an infusion over 30 min. Animals were euthanized at the end of the study and necropsy performed immediately to quantify the extent of dye spread. RESULTS: In seven animals, 20 catheters were successfully placed in the epidural space. The mean (sd) extent of dye spread was 8.9 (2.6) cm in the infusion group compared with 15.2 (2.7) cm in the bolus group (P<0.001). Segmental spread was significantly greater in the bolus group compared with the infusion group (P<0.01). CONCLUSION: In the porcine epidural model, spread of one ml of epidural dye solution is more extensive after a single bolus compared with short term infusion.

Flexion-rotation manoeuvre increases dimension of the acoustic target window for paramedian thoracic epidural access.

BACKGROUND: The posterior longitudinal ligament (PLL) has been found to be a reliable measure of the acoustic target window for lumbar spinal anaesthesia and a predictive tool for difficult spinals. Currently, there is limited information on the PLL in the thoracic spine and its potential use for optimizing the acoustic target window during thoracic epidural placement. This study examined the effects of changes in body position on the length of the PLL as a measure of the acoustic target window for paramedian thoracic epidural access. METHODS: We performed thoracic ultrasonography on 30 adult volunteers to measure the length of the PLL at the T9/10 interspace, in five different positions: P1, neutral; P2, thoracic and lumbar flexion; P3, as in position 2 with dorsal table tilt to 10°; P4, as in position 2 with 45° rightward shoulder rotation; and P5, as in position 2 with 45° leftward shoulder rotation. RESULTS: The mean (sd) PLL length increased significantly from 9.9 (3.9) mm in P1 to 11.7 (3.4) mm in P2, 12.9 (3.1) mm in P3, and 13.8 (4.0) mm in P4 (P<0.01, <0.01, and <0.01, respectively). The mean PLL length in P3 and P4 was also significantly longer compared with P2 (P<0.01 and 0.01, respectively). CONCLUSIONS: In volunteers, flexion with 10° dorsal table tilt and flexion with right rotation significantly increased the length of the ipsilateral PLL, compared with the standard flexed sitting position, as visualized by paramedian ultrasonography at the level of T9/10.

Selective spinal anesthesia for outpatient transurethral prostatectomy (TURP): randomized controlled comparison of chloroprocaine with lidocaine.

BACKGROUND: This is a study comparing two short-acting local anesthetics lidocaine and 2-chloroprocaine in combination with fentanyl, to provide selective spinal anesthesia for outpatient transurethral resection of the prostate (TURP). METHODS: In this prospective, randomized double-blind study, selective spinal anesthesia was performed in 40 American Society of Anesthesiologists I-III outpatients undergoing TURP using either 40 mg of chloroprocaine mixed with 12.5 µg of fentanyl (n = 20) or 35 mg of lidocaine mixed with 12.5 µg of fentanyl (n = 20). The primary outcome was duration of spinal block. Secondary outcomes were time to reach T10 (onset), time to maximal level, duration above T10 and lidocaine 3, maximal level of block, and adverse effects. RESULTS: The median (minimum, maximum) onset time was 4 (1, 16) and 3 (2, 10) min for chloroprocaine and lidocaine, respectively. Time to maximal level was 20 (17, 29) and 22 (16, 26) min for chloroprocaine and lidocaine, respectively. Mean maximal level was T7-T8 for both agents. Duration of block above T10 was 54 (28, 88) and 63 (31, 87) min for chloroprocaine and lidocaine, respectively. Duration of block above lidocaine 3 was 93 (56, 218) and 98 (58, 151) min for chloroprocaine and lidocaine, respectively. There was no statistical difference between the two groups with respect to these clinical end points. Four patients in the lidocaine group developed transient neurological symptoms. One patient in the chloroprocaine group developed a cauda equina-like syndrome but recovered fully after several weeks. CONCLUSIONS: Selective spinal anesthesia with chloroprocaine and lidocaine for TURP yielded comparable results for clinical characteristics. Further research on transient neurological symptom and cauda equina risk with chloroprocaine is warranted.

Mini-audits facilitate quality assurance in outpatient units.

PURPOSE: It has been shown that large-scale epidemiological studies are an unsatisfactory method of measuring quality of care in anesthesia. We performed a mini-audit of the outpatient surgery unit at Vancouver General Hospital to determine whether such methodology would be helpful in assessing and monitoring quality of care and in identifying areas where improvements could be made. METHODS: After institutional approval, we conducted a prospective quality assurance audit in a cohort of 462 consecutive outpatients. A measurement tool was developed using information from previous literature. Data recorded included demographics, type of surgery and anesthesia, duration of stay in the postanesthetic care unit (PACU) and any adverse events in the PACU. The effect of ethnicity on the above was also examined. RESULTS: The demographics and practice profiles of our unit were comparable to other units. The mean duration of stay in the PACU was 91 +/- 55.3 min and is twice as long as other units. The incidence of hypotension, hypothermia and excessive pain in the PACU were higher compared to other centres. The incidence of other adverse events was comparable to that reported by other centres. O2 supplementation was required more frequently in Caucasians (23% vs 9%; P <0.05) and postoperative bleeding occurred more frequently in Asiatics (46% vs 27%; P <0.05). CONCLUSION: A mini-audit was found to be helpful in assessing and monitoring quality of care and in identifying areas where improvements could be made.

Selective spinal anesthesia for outpatient laparoscopy. I: characteristics of three hypobaric solutions.

PURPOSE: To determine the characteristics and recovery profiles of three hypobaric spinal anesthetic solutions. METHODS: Thirty outpatients undergoing outpatient laparoscopy were randomly assigned to receive spinal anesthesia with one of three small-dose solutions. Group I--20 mg lidocaine plus 25 microg fentanyl; Group II--20 mg lidocaine plus 10 microg sufentanil; Group III--10 mg lidocaine plus 10 microg sufentanil. Solutions were diluted to three ml with sterile water for injection. A 27-gauge Whitacre needle was inserted at L2-3 or L3-4 in the sitting position. Sensory and motor recovery were assessed with pinprick, proprioception, light touch and a modified Bromage scale. RESULTS: Operating conditions were good to excellent in all three groups. The incidence of shoulder tip discomfort, pruritus and nausea was not significantly different between groups. Light touch was present in all three groups and proprioception was present in most patients during and after surgery. Group III patients had a more rapid recovery of pinprick analgesia and Group II patients had the slowest recovery of pinprick analgesia. Motor block recovery was comparable in the three groups. Eighty percent of patients in Groups III and I were able to perform 'deep knee bends' and 'straight leg raises' at the end of surgery. CONCLUSION: For short duration laparoscopy, spinal 10 mg lidocaine with 1O microg sufentanil provided selective pin prick analgesia, with preserved touch, proprioception and limited motor block. Operating conditions were satisfactory and most patients were able to fulfill 'walk out' criteria at the end of surgery.

Selective spinal anesthesia for outpatient laparoscopy. II: epinephrine and spinal cord function.

PURPOSE: To compare two small-dose solutions (with and without epinephrine) for spinal anesthesia during outpatient laparoscopy and to determine spinal cord function with these low-dose solutions. METHOD: Twenty outpatients undergoing gynecological laparoscopy were randomly assigned to receive spinal anesthesia with one of two low dose solutions. Group LS-10 mg lidocaine plus 10 microg sufentanil; Group LSE-10 mg lidocaine plus 10 microg sufentanil plus epinephrine 50 microg. Solutions were diluted to three millilitres with sterile water for injection. A 27-gauge Whitacre needle was inserted at L2-3 or L3-4 in the sitting position. Operating conditions and spinal cord function (spinothalamic, dorsal column and motor) were assessed. RESULTS: Operating conditions were good-excellent in both groups. The incidence of shoulder tip discomfort, pruritus and nausea, and the amount of supplementation with alfentanil and midazolam was not different between groups. Most patients in both groups had preserved dorsal column function and normal motor power on arrival in PACU and were able to satisfy 'walk out' criteria. Recovery of pinprick sensation and discharge times were not different. Mild pruritus (VAS score < or = 5) was present in both groups. CONCLUSION: For short duration laparoscopy, addition of 50 microg epinephrine to a small dose of spinal 10 mg lidocaine with 10 microg sufentanil did not provide additional benefit in terms of intraoperative analgesia or operating conditions. Spinal cord function was preserved with small-dose techniques.

Selective spinal anesthesia for outpatient laparoscopy. IV: population pharmacodynamic modelling.

PURPOSE: To apply a population pharmacodynamic model to small-dose hypobaric spinal anesthesia for outpatient laparoscopy. METHODS: The level of spinal analgesia after spinal blockade with small-dose (20-25 mg) hypobaric lidocaine was assessed by means of pinprick in patients undergoing outpatient laparoscopy. In 57 patients, 385 measurements were available for analysis. We first modelled the data for each patient with a mixed-effects model described by Schnider (Model 1). The population mean parameters, inter-individual variance, and residual variance were estimated. Clinically important endpoints (time to reach T10 (onset), time to maximal level, duration and maximally attained level) of each patient were calculated based on the estimated time course of analgesia level for each patient. The model was used to predict the later data with respect to level of spinal analgesia of each patient from fits based on the observed data in the first 75 min. RESULTS: The mean +/- SD onset time was 8.3 +/- 1.9 min, time to maximal level was 20.8 +/- 5.3 min, duration of effect was 37.9 +/- 13.1 min, and mean maximal level was T5. There was a good correlation (R2 = 0.90) between the observed levels of analgesia and those predicted from the model. Data from the first 75 min predicted the later observed data for each patient moderately well (R2 = 0.38). CONCLUSION: A population pharmacodynamic model was applied to low-dose hypobaric lidocaine spinal anesthesia. Clinically important endpoints were determined and forecasting of later data with respect to level of spinal analgesia was attempted. Such an approach may be useful in the management of low-dose spinal anesthetic techniques in outpatients.

Selective spinal anesthesia for outpatient laparoscopy. III: sufentanil vs lidocaine-sufentanil.

PURPOSE: The efficacy of low dose intrathecal lidocaine-sufentanil was compared with intrathecal sufentanil for short duration outpatient gynecological laparoscopy. METHODS: Thirteen ASA I and II patients undergoing gynecological laparoscopy were studied in a randomized double-blind trial. Patients received either intrathecal 10 mg lidocaine plus 10 microg sufentanil (Group LS) or intrathecal 20 microg sufentanil (Group S), each diluted to 3 mL with sterile water through a 27g Whitacre needle in the sitting position. Sensory and motor recovery were assessed with pinprick and a modified Bromage scale. RESULTS: One of seven Group LS patients and two of five Group S patients required conversion to general anesthesia for failed skin test with forceps. Two of the remaining three Group S patients felt sharpness with skin incision. The study was terminated early because of inadequate anesthesia in Group S. The small sample size (n = 9) made statistical analysis uninformative. CONCLUSION: Intrathecal 20 microg sufentanil is unsuitable as a sole agent for gynecological laparoscopy.

Selective spinal anesthesia for outpatient laparoscopy. V: pharmacoeconomic comparison vs general anesthesia.

PURPOSE: To compare the cost and effectiveness of small-dose spinal anesthesia (SP) with general anesthesia (GA) for outpatient laparoscopy. METHODS: A retrospective record analysis of 24 patients who received SP were compared with 28 patients who received GA in our Daycare centre. The costs of anesthesia and recovery were calculated, from an institutional perspective, using 1997 Canadian Dollar values. Effectiveness was measured in terms of time for anesthesia and recovery, and postoperative antiemetic and analgesic requirements. RESULTS: Both groups were well matched for age, weight, duration and type of surgery. The mean total cost for the SP group of $53.45 +/- 10.40 was no different from that for the GA group of $48.92 +/- 10.25 (95% CI -10.3, 1.2). Time to administer anesthesia was longer in the SP group with a mean time of 18 +/- 8 min compared with 10 +/- 3 min in the GA group (CI -11.3, -4.7). Recovery time in the PACU was longer in the SP group 123 +/- 51 min compared with 94 +/- 48 min (CI -56.6,-1.4). Postoperative antiemetic requirements were similar: 8% in SP group vs 14% in GA group, whereas analgesic requirements were less in the SP group with 25% receiving analgesia compared with 75% in the GA group (P < 0.05). CONCLUSION: The total cost of anesthesia and recovery using SP is similar to that for GA when used for outpatient laparoscopy. Spinal anesthesia was less effective than GA in time to administer anesthesia and in duration of recovery. Postoperative analgesic requirements were reduced using SP.

Regional anesthesia for laparoscopy.

A variety of laparoscopic procedures can be performed on patients under regional anesthesia. Diagnostic laparoscopy in elective and emergency patients, pain mapping, laparoscopy for infertility, and tubal sterilization are some examples. The key benefits of regional anesthesia include less emesis, less postoperative pain, shorter postoperative stay, improved patient satisfaction, and overall safety. Regional techniques, such as rectus sheath blocks, inguinal blocks, and caudal blocks, are useful adjuncts to general anesthesia and facilitate postoperative analgesia. Other techniques, such as spinal and epidural anesthesia, and combination of the two, are suitable as a sole anesthetic technique for laparoscopy. The physiologic changes during laparoscopy in the awake patient appear to be tolerated well under regional anesthesia. It is reasonable to assume that with advances in instrumentation and surgical techniques, the role of laparoscopy will increase in the future. The benefits conferred by regional anesthesia make it an attractive option to general anesthesia for many patients and procedures. Successful implementation of regional anesthesia is an important determinant of how anesthesiologists, surgeons, and surgical facilities cope with new challenges. In the future, it could be possible to provide "walk-in/walk-out" regional anesthesia with a real possibility of fast tracking patients through the recovery process after ambulatory surgery. For maximal patient safety, however, facilities offering regional anesthesia must have appropriately trained anesthesia personnel and the equipment necessary for monitoring and providing full resuscitation in the event of complications or a need to convert to general anesthesia.

Tracheal intubation of outpatients with and without muscle relaxants.

PURPOSE: To compare intubating conditions and postoperative myalgias in outpatients after intubation with propofol/alfentanil compared with propofol/alfentanil/succinylcholine with and without precurarisation with d-tubocurarine. METHODS: 144 ASA I-II ambulatory patients for dental extraction under anesthesia were studied. Subjects received either 3 mg d-tubocurarine (Group II) or saline (Groups I, III) i.v. prior to induction of anesthesia with 20 microg x kg(-1) alfentanil and 2.5 mg x kg(-1) propofol followed by 1.5 mg x kg(-1) succinylcholine (II and III) or saline 0.9% (I) for muscle relaxation. The ease of airway management and the postoperative incidence, severity and distribution of muscle pains were examined. RESULTS: Intubation was successful in all patients and there were no differences in jaw mobility, ease of bag-mask ventilation, visualization of the vocal cords or cord position. Limb movement was more common during intubation in Group I (37.5%) than in Group III (8.3%) or Group II (2%), P < 0.05. At home, VAS scores for myalgia were higher in Group III than in Group I and II. Neck myalgia was more common in Group II (72%) than in Groups II (44%) and I (41%), P < 0.05. Myalgias were also more common in Group III patients (P < 0.05). CONCLUSION: Acceptable intubating conditions were achieved with propofol and alfentanil alone. Succinylcholine reduced limb movement during intubation but was associated with postoperative myalgias for up to five days. Precurarisation with tubocurarine reduced the severity of succinylcholine myalgia.