Unilateral spinal anesthesia or combined sciatic-femoral nerve block for day-case knee arthroscopy. A prospective, randomized comparison.

BACKGROUND: To evaluate the time required to achieve surgical block and fulfill standardized discharge criteria in outpatients receiving knee arthroscopy with either unilateral spinal anesthesia or combined sciatic-femoral nerve block. METHODS: After a standard midazolam/ketoprofen premedication and baseline measurement of cardiovascular parameters, 50 ASA physical status I-II patients scheduled for elective outpatient knee arthroscopy were randomized to receive unilateral spinal anesthesia with 8 mg of 0.5% hyperbaric bupivacaine injected without barbotage through a 25-gauge Whitacre spinal needle (group USA, n = 25), or combined sciatic-femoral nerve block with 25 ml of 2% mepivacaine (15 ml for femoral nerve block and 10 ml for sciatic nerve block) (group SFNB, n = 25). Times from local anesthetic injection to achievement of surgical block defined as the presence of adequate motor (complete motor blockade of the operated limb in the USA group and inability to move the ankle and the knee of the operated limb in the SFNB group) and sensory (loss of pinprick sensation at T12 on the operated side in the USA group, or in the femoral and sciatic nerves distribution in the SFNB group) blocks was recorded. Times to block resolution, urination, unassisted ambulation, and readiness to home discharge were also recorded by a blind observer, as well as occurrence of untoward events during surgery. RESULTS: Surgical block was achieved in 15 +/- 6 min in group USA and 16 +/- 6 min in group SFNB (p = NS). No differences in hemodynamic undesired effects and success rate were observed. Even though USA patients showed a faster time to ambulation (166 +/- 44 min versus 217 +/- 49 min, p = 0.002) and later urination (240 +/- 90 min versus 145 +/- 36 min, p = 0.0001) than SFNB group, no differences in home discharging were reported (246 +/- 98 min versus 211 +/- 77 min, respectively). Bladder catheterization was required in 2 patients of USA group only; however, no patient was admitted to the hospital because of urinary retention. CONCLUSIONS: In outpatient knee arthroscopy, a combined sciatic-femoral nerve block with 2% mepivacaine provides similarly successful anesthesia with onset times and home discharge similar to those provided by unilateral spinal anesthesia.

Regional anaesthesia for outpatient knee arthroscopy: a randomized clinical comparison of two different anaesthetic techniques.

BACKGROUND: The purpose of this prospective, randomized study was to evaluate the time required to perform anaesthesia, achieve surgical block and fulfil standardized discharge criteria in outpatients receiving knee arthroscopy with either spinal anaesthesia or combined sciatic-femoral nerve block. METHODS: After a standard midazolam/ketoprofen premedication and baseline measurement of cardiovascular parameters, 50 ASA I-II patients scheduled for elective outpatient knee arthroscopy were randomized to receive spinal anaesthesia with 8 mg of 0.5% hyperbaric bupivacaine (group Spinal, n=25), or combined sciatic-femoral nerve block with 25 ml of mepivacaine 20 mg ml(-1) and a multiple injection technique (15 ml for femoral nerve block and 10 ml for sciatic nerve block). Times lasting from skin disinfection to the end of local anaesthetic injection (preparation time) and then to achieve surgical anaesthesia (readiness for surgery), as well as times required for block resolution, micturition, unassisted ambulation, and home discharge were recorded by a blinded observer. Occurrence of adverse events was also recorded. RESULTS: Preparation time (mean+/-SD) was longer with sciatic-femoral block (8+/-2.7 min) than spinal anaesthesia (5+/-2.1 min) (P=0.0002) while no differences were observed in the time required to achieve readiness for surgery (14+/-5 min and 15+/-6 min in the Spinal and Sciatic-femoral groups, respectively). No differences in haemodynamic side effects and need for intraoperative additional analgesia were observed. Patients receiving spinal anaesthesia showed a faster resolution of nerve block and longer time to micturition (137+/-49 min and 231+/-101 min) than patients receiving peripheral nerve blockade (206+/-51 min and 145+/-36 min) (P<0.0005 and P=0.002, respectively); however, no differences were observed in the time required to fulfil standardized discharge criteria (241+/-101 min in group Spinal and 209+/-70 min in group Sciatic-femoral; P=0.86). CONCLUSION: In patients receiving elective outpatient knee arthroscopy, using a combined sciatic-femoral nerve block with 25 ml of mepivacaine 20 mg ml(-1) and a multiple injection technique results in a slightly longer preoperative time but provides similarly effective anaesthesia with no differences in home discharge times as compared to spinal anaesthesia with 8 mg hyperbaric bupivacaine.

Interscalene brachial plexus anesthesia with either 0.5% ropivacaine or 0.5% bupivacaine.

BACKGROUND: To compare intra- and postoperative clinical properties of interscalene brachial plexus block performed with either 0.5% ropivacaine or 0.5% bupivacaine. EXPERIMENTAL DESIGN: prospective, randomized, double-blind study. SETTING: in patient at the University Hospital, Department of Orthopedic Surgery. PATIENTS: 30 ASA physical status I-II patients scheduled for elective shoulder surgery. INTERVENTIONS: interscalene brachial plexus block was performed using the multiple injection technique and a nerve stimulator by injecting 20 ml of either 0.5% ropivacaine (n = 15) or 0.5% bupivacaine (n = 15). Postoperative analgesia consisted of 100 mg intravenous ketoprofen, if required. A blind observer evaluated hemodynamic variables as well as sensory and motor blocks from the end of injection to achieve a surgical anesthesia (readiness for surgery: loss of pinprick sensation from C4 to C7 with the inability to elevate the operated limb against gravity). The time lasting from block placement to first requirement for postoperative pain medication was also recorded. RESULTS: No differences in anthropometric parameters and hemodynamic variables were observed throughout the study, and no signs of central nervous system (CNS) and cardiovascular toxicity, or other untoward events were reported in any patients. Readiness for surgery was obtained after 28 +/- 15 min with 0.5% bupivacaine and 22 +/- 8 min after 0.5% ropivacaine (p = NS). No differences in postoperative pain relief was observed between the two groups (11.1 +/- 5 hrs after 0.5% ropivacaine and 10.9 +/- 3.9 hrs after 0.5% bupivacaine, respectively). CONCLUSIONS: This study confirmed that 0.5% ropivacaine has clinical properties similar to those of 0.5% bupivacaine, when used for interscalene brachial plexus block, providing similarly long duration in postoperative pain relief. Compared with bupivacaine, ropivacaine has the further advantage of a lower potential for central nervous system and cardiovascular toxicity.

Arterial to end-tidal carbon dioxide tension difference in anaesthetized adults mechanically ventilated via a laryngeal mask or a cuffed oropharyngeal airway.

To evaluate arterial (PaCO2), end-tidal (PETCO2) and carbon dioxide tension difference during mechanical ventilation with extratracheal airways, 60 patients ASA physical status I-II, receiving general anaesthesia for minor extra-abdominal procedures were randomly allocated to receive either a cuffed oropharyngeal airway (group COPA, n = 30) or a laryngeal mask (group LMA, n = 30). The lungs were mechanically ventilated by IPPV using a 60% nitrous oxide and 1-1.5% isoflurane in oxygen mixture (VT = 8 mL kg-1; RR = 12 b min-1; l/E = 1/2). After PETCO2 had been stable for at least 10 min after airway placement, haemodynamic variables and PETCO2 were recorded and an arterial blood sample was obtained for measurement of PaCO2. No differences in anthropometric parameters, smoking habit, haemodynamic variables and incidence of untoward events were observed between the two groups. Airway manipulation, to maintain adequate ventilation, was required in only nine patients in the cuffed oropharyngeal airway group (30%) (P < 0.0005); however, in no case was it necessary to remove the designated extratracheal airway due to unsuccessful mechanical ventilation. The mean difference between arterial and end-tidal carbon dioxide partial pressure was 0.4 +/- 0.3 KPa in the laryngeal mask group (95% confidence intervals: 0.3-0.5 KPa) and 0.3 +/- 0.26 KPa in the cuffed oropharyngeal airway group (95% confidence intervals: 0.24-0.4 KPa) (P = NS). We conclude that in healthy adults who are mechanically ventilated via the cuffed oropharyngeal airway, the end-tidal carbon dioxide determination is as accurate an indicator of PaCO2 as that measured via the laryngeal mask, allowing capnometry to be reliably used to evaluate the adequacy of ventilation.