Wrong-site nerve blocks: 10 yr experience in a large multihospital health-care system.

INTRODUCTION: Although wrong-site surgery has garnered extensive scrutiny, the incidence of wrong-site blocks remains unknown. Our study thus sought to quantify the incidence of wrong-site blocks and examine some of their associated risk factors in our multihospital health-care system. METHODS: Using quality-improvement and billing data, we quantified the total number of blocks and wrong-site blocks occurring between July 1, 2002 and June 30, 2012 within the University of Pittsburgh Medical Center Health System. The incidence of wrong-site block was determined by block type, hospital, and type of service involved in performing the block. The incidence of wrong-site block was compared with that of wrong-site surgery. Fisher's exact tests were performed to determine associations between the incidence of wrong-site block and any of the aforementioned variables. A root-cause analysis was performed to determine the source of wrong-site blocks after the implementation of a timeout policy. RESULTS: Of the 85 915 patients receiving blocks, 70 441 received only unilateral blocks, yielding an overall incidence of wrong-site block of 1.28 (95% confidence interval 0.43-2.13) per 10 000 patients receiving unilateral blocks. The incidence of wrong-site block was highest with femoral blocks, and differed from the incidence of wrong-site surgery. All occurrences of wrong-site block after the implementation of the timeout policy involved policy violations. CONCLUSIONS: Our study provides the first incidence data on wrong-site block in a large patient population and can help hospitals to develop policies based on these data. It is yet to be determined whether active intervention can eliminate this adverse event.

The nerve stimulation technique versus the loss of resistance technique for the posterior approach to lumbar plexus block: a randomized, prospective, observer-blinded, pilot study.

BACKGROUND: This prospective, randomized, observer-blinded, pilot study compares the effects of the nerve stimulation guidance technique (NS) with the loss of resistance technique (LOR) on readiness for surgery during the posterior approach to lumbar plexus block. METHODS: Thirty ASA status I-III patients who were 18-85 years old and who were undergoing hip fracture repair were enrolled. After parasacral sciatic nerve block, patients were randomly allocated to receive a continuous posterior lumbar plexus block using nerve stimulation (n=15) or a continuous psoas compartment block using the loss of resistance technique (n=15) with 20 ml of 1.5% mepivacaine. A blinded observer monitored for sensory and motor block onsets every 5 minutes. We defined readiness for surgery as complete numbness to the pinprick test and complete motor block on the surgical side. If incomplete, the lumbar plexus block was supplemented with 10 mL of 1.5% mepivacaine through the catheter before surgery. Intraoperative fentanyl or general anesthesia requirements, pain scores, local anesthetic consumption, morphine requirements for breakthrough pain and side effects were monitored. RESULTS: The mean time to readiness for surgery was 12±6 min Group NS and 22±6 min in Group LOR (P=0.03). Three patients in Group NS and 9 patients in Group LOR required additional boluses of local anesthetic through the lumbar plexus catheter before surgery (P=0.113). CONCLUSION: Nerve stimulation allowed faster readiness for surgery than loss of resistance. Nevertheless, the two techniques seem to be comparable in terms of local anesthetic consumption, morphine requirements and pain scores.

Continuous peripheral nerve blocks in acute pain management.

The indications for continuous nerve blocks for the perioperative pain management in hospitalized and ambulatory patients have extended well beyond orthopaedics. These techniques are not only used to control pain in patients undergoing major upper and lower extremity surgery, but also to provide perioperative analgesia in patients undergoing abdominal, plastic, urological, gynaecological, thoracic, and trauma surgeries. Infusion regimens of local anaesthetics and supplements must take into consideration the condition of the patient before and after surgery, the nature and intensity of the surgical stress associated with the surgery, and the possible need for immediate functional recovery. Continuous nerve blocks have proved safe and effective in reducing opioid consumption and related side-effects, accelerating recovery, and in many patients reducing the length of hospital stay. Continuous nerve blocks provide a safer alternative to epidural analgesia in patients receiving thromboprophylaxis, especially with low molecular-weight heparin.

International normalized ratio and prothrombin time values before the removal of a lumbar plexus catheter in patients receiving warfarin after total hip replacement.

BACKGROUND: There is a paucity of data regarding the coagulation status when discontinuing perineural catheters in patients receiving anticoagulant after operation. This retrospective study was designed to establish international normalized ratio (INR) and prothrombin time (PT) at the time of removal of lumbar plexus perineural catheters in patients receiving warfarin after total hip replacement. METHODS: Patients who received a continuous lumbar plexus nerve block for postoperative analgesia and received warfarin after total hip surgery between August 2002 and June 2007 were included in this retrospective study. PT and INRs were recorded before surgery and every day after operation along with any post-surgical nerve injury and bleeding related to the removal of the perineural catheter. RESULTS: Six hundred and seventy patients met the inclusion criteria. Almost all lumbar plexus catheters (89%) were removed on postoperative day 2. At the time of the perineural catheter removal, 36.2% of patients had an INR >1.4 (range: 1.5-3.9). One case of local bleeding was recorded at the time of the catheter removal with an INR of 3.0. This was managed with a direct pressure at the site. CONCLUSIONS: Although in this retrospective analysis, we demonstrated that lumbar plexus catheters were removed with an INR > or =1.5, additional data are required to confirm the safety of such an approach.

Single-dose aprepitant vs ondansetron for the prevention of postoperative nausea and vomiting: a randomized, double-blind phase III trial in patients undergoing open abdominal surgery.

BACKGROUND: The neurokinin(1) antagonist aprepitant is effective for prevention of chemotherapy-induced nausea and vomiting. We compared aprepitant with ondansetron for prevention of postoperative nausea and vomiting. METHODS: Nine hundred and twenty-two patients receiving general anaesthesia for major abdominal surgery were assigned to receive a single preoperative dose of oral aprepitant 40 mg, oral aprepitant 125 mg, or i.v. ondansetron 4 mg in a randomized, double-blind trial. Vomiting episodes, use of rescue therapy, and nausea severity (verbal rating scale) were documented for 48 h after surgery. Primary efficacy endpoints were complete response (no vomiting and no use of rescue therapy) 0-24 h after surgery and no vomiting 0-24 h after surgery. The secondary endpoint was no vomiting 0-48 h after surgery. RESULTS: Aprepitant at both doses was non-inferior to ondansetron for complete response 0-24 h after surgery (64% for aprepitant 40 mg, 63% for aprepitant 125 mg, and 55% for ondansetron, lower bound of 1-sided 95% CI > 0.65), superior to ondansetron for no vomiting 0-24 h after surgery (84% for aprepitant 40 mg, 86% for aprepitant 125 mg, and 71% for ondansetron; P < 0.001), and superior for no vomiting 0-48 h after surgery (82% for aprepitant, 40 mg, 85% for aprepitant, 125 mg, and 66% for ondansetron; P < 0.001). The distribution of peak nausea scores was lower in both aprepitant groups vs ondansetron (P < 0.05). CONCLUSIONS: Aprepitant was non-inferior to ondansetron in achieving complete response for 24 h after surgery. Aprepitant was significantly more effective than ondansetron for preventing vomiting at 24 and 48 h after surgery, and in reducing nausea severity in the first 48 h after surgery. Aprepitant was generally well tolerated.

Stimulating or conventional perineural catheters after hallux valgus repair: a double-blind, pharmaco-economic evaluation.

BACKGROUND: We prospectively evaluated direct analgesia-related costs of continuous sciatic nerve block using either a stimulating or conventional catheter after hallux valgus repair. METHODS: The perineural catheter was inserted through a stimulating introducer either blindly (group Conventional, n= 38) or while stimulating via the catheter (group Stimulating, n= 38). Nerve block was induced with 25 ml of mepivacaine 15 mg/ml, and was followed 3 h later by a patient-controlled infusion of ropivacaine 2 mg/ml (basal infusion: 3 ml/h; incremental dose: 5 ml; lock-out time: 30 min). Rescue tramadol [100 mg intravenous (i.v.)] was given if required. Local anesthetic consumption, need for rescue tramadol and post-operative nausea and vomiting (PONV) treatment, and patient's satisfaction were recorded during first 24-h infusion. Cost calculations were based on the acquisition cost of drugs and devices. RESULTS: Both techniques were similarly effective, but local anesthetic consumption and need for rescue analgesics were lower in the Stimulating group [respectively, 120 vs. 153 ml (P= 0.004) and 21% vs. 60% (P= 0.001)]. The analgesia-related costs for 24 h were similar when 100-ml bags of ropivacaine 2 mg/ml were used (66 euro vs. 67 euro; P= 0.26). When 200-ml bags of ropivacaine were used, the analgesia-related costs were higher in the Stimulating group than the Conventional group (75 euro vs. 55 euro; P= 0.0005). CONCLUSIONS: Direct costs of continuous sciatic nerve block ranged from 55 to 75 euro. Stimulating catheters reduced local anesthetic consumption and need for rescue analgesics. This was only cost effective when 100-ml bags of 2 mg/ml ropivacaine were used, while the cheapest combination was the use of conventional catheters and 200-ml bags of ropivacaine.

Lidocaine versus ropivacaine for continuous interscalene brachial plexus block after open shoulder surgery.

BACKGROUND: This study compared the postoperative infusion of 1% lidocaine and 0.2% ropivacaine for continuous interscalene analgesia in patients undergoing open shoulder surgery. METHODS: Forty patients undergoing open shoulder surgery received an interscalene brachial plexus block with 30 ml of either 1.5% lidocaine (n = 20) or 0.5% ropivacaine (n = 20), followed by a continuous patient-controlled interscalene analgesia with 1% lidocaine or 0.2% ropivacaine, respectively. A blinded observer recorded the quality of analgesia and recovery of motor function during the first 24 h of infusion. RESULTS: Onset of the block occurred after 7.5 (5-40) min with lidocaine and 30 (10-60) min with ropivacaine (P = 0.0005). Postoperative pain intensity was higher with lidocaine than ropivacaine for the first 8 h of infusion. The ratio between boluses given and demanded from the pump was 0.5 (0.13-0.7) with lidocaine and 0.7 (0.4-1.0) with ropivacaine (P = 0.005). Rescue IV tramadol was required during the first 24 h of infusion by 16 patients of the lidocaine group (84%) and eight patients of the ropivacaine group (46%) (P = 0.05). At the 16 h and 24 h observation times a larger proportion of patients receiving ropivacaine had complete regression of motor block (70% and 95%) than patients receiving lidocaine (50% and 55%) (P = 0.05 and P = 0.013, respectively). CONCLUSIONS: Although 1% lidocaine can be effectively used for postoperative patient-controlled interscalene analgesia, 0.2% ropivacaine provides better pain relief and motor function.

Role of propofol and its solvent, intralipid, in nitric oxide-induced peripheral vasodilatation in dogs.

BACKGROUND: The commercial propofol preparation in an intralipid solution causes marked vasodilatation. Both propofol and its solvent seem to stimulate the nitric oxide (NO) pathway. The role of intralipid in cardiac and regional haemodynamic changes induced by propofol and their respective interactions with the NO pathway was assessed. METHODS: Dogs were instrumented to record arterial pressure, heart rate, cardiac output, dP/dt (the first derivative of left ventricular pressure) and vertebral, carotid, coronary, mesenteric, hepatic, portal and renal blood flows. Experimental groups were as follows. Group 1 (control; n = 11): N-methyl-L-arginine (L-NMA) 20 mg kg-1 i.v.; Group 2 (n = 8): propofol (10 mg ml-1) 4 mg kg-1 i.v. bolus followed by 0.6 mg kg-1 min-1; Group 3 (n = 6): intralipid 0.25 ml kg-1 bolus followed by 0.06 ml kg-1 min-1. After 60 min, L-NMA was injected in Groups 2 and 3. RESULTS: Propofol induced increases in heart rate, coronary and carotid blood flows, and decreases in systemic vascular resistance and dP/dt. Intralipid increased renal blood flow, carotid vascular resistance and mesenteric vascular resistance. In the presence of intralipid, L-NMA-induced pressor response and systemic, carotid and renal vasoconstriction were more pronounced than in control dogs. CONCLUSIONS: Except for the coronary and carotid circulations, intralipid modulates the NO pathway in cardiac and regional blood flow.

Reduction of operating and recovery room times and overnight hospital stays with interscalene blocks as sole anesthetic technique for rotator cuff surgery.

BACKGROUND: The effort to decrease hospital stays and to increase operating room efficacy has become an important consideration in the practice of anesthesia. METHODS: Fifty-three patients who underwent shoulder rotator cuff repair in the sitting position were divided into four groups according to the anesthesia technique used: Group 1 (general anesthesia), Group 2 (interscalene block), Group 3 (interscalene combined with general anesthesia) and Group 4 (general anesthesia combined with local injection of local anesthetics). Interscalene blocks were performed preoperatively, using a nerve stimulator. After appropriately locating the brachial plexus, a mixture of 40 ml of 2% lidocaine and 0.5% bupivacaine (v/v) was injected. RESULTS: As compared to general anesthesia, the use of an interscalene block alone reduced the following operating room times: 1) from the patient's arrival in the operating room to the beginning of surgery and 2) from the end of surgery to the patient's departure from the operating room. Use of the interscalene block also resulted in a reduction of recovery time when compared to Groups 1, 3 and 4 by 40, 56 and 66%, respectively. Compared to Group 1, this anesthesia technique was furthermore associated with a 64% decrease in the number of patients hospitalized overnight. CONCLUSIONS: This study confirms that the interscalene block as sole anesthesia technique is safe and effective and can contribute to shorten the hospital length of stay of patients undergoing shoulder rotator cuff surgery.

Blocks at the wrist provide effective anesthesia for carpal tunnel release.

PURPOSE: Distal blocks are not recommended even for a short procedure when a tourniquet is used. This study was designed to evaluate the tolerance, effectiveness, patient acceptance and safety of distal blocks at the wrist. METHODS: Consecutive patients (n=273, mean age 53 +/-15 yr) undergoing endoscopic carpal tunnel release with a pneumatic tourniquet were included in this study. The median nerve was blocked 6 cm above the wrist crease by injecting 10 mL of 2% lidocaine and 0.5% bupivacaine (v/v). The ulnar nerve was blocked by injecting 8 mL of the same anesthetic mixture below the flexor carpi ulnaris tendon 6 cm above the wrist crease. Finally, 2 mL of local anesthetic were infiltrated sc and laterally below the crease to block the musculocutaneous nerve. The intensity of the block was evaluated after five, ten and 20 min. In addition, pain associated with block performance and tolerance of the tourniquet were evaluated. Finally, neurological complications associated with this technique were investigated. Data are presented as means +/- SD. RESULTS: At ten minutes after the block was performed, 9% and 32% of patients required an additional injection to complete the block in the median and ulnar territories, respectively. In more than 75% of patients, performance of the block was associated with either no or mild pain. The tourniquet was inflated for 12.6 +/- 5.4 min and was well tolerated in 99% of patients. Finally, neither transient nor permanent neurological deficit were recorded postoperatively. CONCLUSION: Blocks at the wrist are effective, well accepted by the patient and safe when a pneumatic tourniquet is used for a short procedure.

Role of heparin and nitric oxide in the cardiac and regional hemodynamic properties of protamine in conscious chronically instrumented dogs.

BACKGROUND: Because protamine is administered to reverse heparin, a drug that might itself affect the pharmacologic properties of protamine, this study was designed to assess the properties of protamine alone and in the presence of heparin in conscious dogs. METHODS: Twelve dogs were instrumented to continuously record cardiac and regional hemodynamics. On separate occasions, a dose of protamine (0.5, 1, 3, 5, and 8 mg/kg) was randomly administered either alone or in the presence of heparin (ratio 100 IU/mg). Heparin (300 IU/kg) and protamine (3 mg/kg) were administered in the presence of N-methyl-L-arginine, a specific nitric oxide synthase inhibitor. Identical experiments were performed with protamine (8 mg/kg) in the absence of heparin on a separate occasion. RESULTS: Protamine alone produced limited cardiac and regional changes. In the presence of heparin, protamine produced hypotension at 3, 5, and 8 mg/kg, vasodilatation at 3 and 5 mg/kg, and a more pronounced dose-dependent increase in pulmonary pressure at 3, 5, and 8 mg/kg. Simultaneously, transient carotid vasodilatation at 3 and 5 mg/kg, coronary and hepatic vasodilatation at 3, 5, and 8 mg/kg, as well as a decrease in vertebral vascular resistance were recorded at 1, 3, and 8 mg/kg. Protamine produced an immediate increase followed by a secondary decrease in renal vascular resistance. Protamine-induced secondary pulmonary pressor effects were attenuated. In the presence of heparin, nitric oxide synthase blockade selectively attenuated protamine-induced immediate hypotension, systemic vasodilatation, and coronary, mesenteric, and hepatic vasodilations as well as the decrease in portal blood flow and accentuated the renal vasoconstriction. CONCLUSIONS: The presence of heparin accentuated the decrease in cardiac function induced by protamine as well as its effects on regional circulation. The data provide evidence that the nitric oxide pathway is involved in the systemic and selective regional heparin-protamine-mediated vasodilatation in conscious dogs.

Continuous femoral blocks improve recovery and outcome of patients undergoing total knee arthroplasty.

This study was designed to determine the effects of continuous femoral infusion (CFI) on total knee arthroplasty recovery. A total of 92 patients were distributed in 3 groups: Patients in group 1 received general anesthesia followed by patient-controlled analgesia (PCA) with morphine (n = 33), patients in group 2 received 3-in-1 and sciatic blocks followed by CFI (n = 29), and patients in group 3 received epidural analgesia (n = 30). Blocks reduced postoperative morphine requirement by 74% (vs group 1; P<.05) and 35% (vs group 3; P<.05). Blocks provided better recovery than PCA with morphine or an epidural. The use of CFI was associated with a reduction of postoperative bleeding by 72% (vs group 1; P<.05) and allowed better performance on continuous passive motion. CFI was associated with a 90% decrease in serious complications and a 20% decrease in the length of hospitalization. CFI represents a better alternative than PCA or epidural analgesia for postoperative pain management and immediate rehabilitation after total knee arthroplasty.

Measurement of cardiac function in conscious rats.

The goal of this study was to establish that 1. blood velocity profile in the rat aorta is parabolic, and 2. measure of left ventricular thickening fraction can be used in rats. Spontaneously hypertensive and normotensive Wistar Kyoto rats were instrumented with a 20-MHz pulsed Doppler flow probe around the thoracic aorta and a 20-MHz pulsed Doppler thickening probe on the left ventricle. Doppler frequency shifts were measured throughout the entire aorta diameter, and individual blood velocity profiles were constructed. It was demonstrated that blood velocity in the ascending aorta of rats is laminar; therefore, cardiac output can be measured using the pulsed Doppler method. In Wistar Kyoto rats, left ventricular thickening fraction was 24 +/- 1% and 25 +/- 1%, 2 and 3 weeks following surgery. In spontaneously hypertensive rats, left ventricular thickening fraction was 22 +/- 2%. Halothane depressed left ventricular thickening fraction, whereas isoproterenol increased left ventricular thickening fraction in conscious rats. Thus, pulsed Doppler technique is a valuable tool for evaluating cardiovascular function in conscious rats.

Comparison of cardiac and regional hemodynamic responses to N-methyl-L-arginine and aminoguanidine infusions in conscious pigs.

The aim of this study was to elucidate cardiac and regional hemodynamics using a nonspecific inhibitor of the constitutive and inducible nitric oxide synthase (NOS), N-methyl-L-arginine (L-NMA), and a specific inhibitor of the inducible NOS, aminoguanidine, in conscious pigs. Animals were divided into two groups. After hemodynamics were stabilized, animals in group 1 (n = 5) received an infusion of L-NMA at 300 microg/kg per min, i.v., over 60 min, and group 2 (n = 5) received an infusion of aminoguanidine, infused at 1 mg/kg per min over 60 min. Hemodynamic parameters including arterial blood pressure, heart rate, cardiac output, dP/dt, and carotid, coronary, hepatic, portal, mesenteric, and renal blood flows were continuously recorded before and 5, 15, 30, 45, 60, and 120 min after L-NMA infusion or aminoguanidine infusion, or both. The L-NMA vasopressor response (20%) was associated with a significant increase in systemic vascular resistance (45%). Carotid, hepatic, and renal vascular resistance increased significantly by 95%, 110%, and 20%, respectively, at 60 min after L-NMA infusion. Finally, heart rate, cardiac output, dP/dt, and portal and mesenteric blood flows remained unchanged after L-NMA infusion. In contrast, aminoguanidine infused at 1 mg/kg per min over 60 min did not change systemic arterial blood pressure or regional blood flow in conscious pigs. Furthermore, aminoguanidine had no effect on acetylcholine vasodilator effects. In conclusion, the lack of pressor effects and of agonist-stimulated NO production induced by aminoguanidine suggests that aminoguanidine is a weak inhibitor of the constitutive NOS. Compared with L-NMA, the selectivity of aminoguanidine may decrease possible side effects that could occur as a result of inhibition of constitutive NOS.

Antinociceptive and cardiovascular properties of esmolol following formalin injection in rats.

PURPOSE: To assess the role of esmolol, a beta1 receptor blocker, in the modulation of pain in the absence of anesthesia. METHODS: Rats were chronically instrumented to record mean arterial blood pressure (MAP) and heart rate (HR). Animals were divided into three groups. Group 1 [esmolol high (EH) 150 mg x kg(-1) x hr(-1); n = 9], Group 2 [esmolol low (EL) 40 mg x kg(-1) x hr(-1); n = 7] and Group 3 saline (n = 9). Formalin 5% was injected in the rat hind paw. Formalin-induced lifting, MAP and HR were recorded at five minute intervals for 35 min after formalin injection. RESULTS: Formalin was associated with an early (Phase 1; 0-5 min) and late nociceptive response (Phase 2; 10-35 min). Esmolol did not affect Phase 1. Although low dose esmolol had minimum effects on nociceptive Phase 2, it was diminished with high dose esmolol. Formalin induced biphasic increases in MAP and HR. Although esmolol did not affect the initial increase in MAP, high dose esmolol blunted the secondary increase in MAP Both low and high doses of esmolol inhibited formalin-induced tachycardia during the first 30 min. CONCLUSION: Our data suggest that esmolol leads to analgesia and reduction of cardiovascular responses to pain.

[Peripheral blocks for the lower limb: lumbar plexus]. / Blocchi periferici per l'arto inferiore: il plesso lombare.

BACKGROUND: The techniques of continuous peripheral blockades have shown to be efficient in postoperative pain control, in the various orthopaedic procedures of the limbs. The aim of this study is to evaluate the existing data about the use of a continuous blockade of the lumbar plexus or femoral nerve, together with the indications for technique and therapy. METHODS: We considered the principal results of prospective, randomised studies described in literature about the assessment of a continuous peripheral blockade of the lumbar plexus or the femoral nerve in limb surgery. Furthermore we described the principal techniques for positioning the perinerval catheters in the considered sites, and the advised dosage regimen. RESULTS: The various studies report an adequate costs/benefits relation concerning the used techniques. The analysed studies not only report an adequate efficacy of the postoperative pain control, but often show an important benefit in terms of functional recovery of the operated limbs and on final outcome of the patient. CONCLUSIONS: The use of continuous blockades of the lumbar plexus or femoral nerve shows to be an important and effective instrument not only in terms of positive effects on postoperative pain control, but also in terms of relevant advantages concerning final outcome after surgery. Nevertheless these techniques should not be considered as the only approach to postoperative pain in the orthopaedic patient, but have to be included in a global, multidisciplinary and multimodal approach.