Intra-operative lidocaine in the prevention of vomiting after elective tonsillectomy in children: A randomised controlled trial.

BACKGROUND: Postoperative vomiting (POV) is a frequent complication of tonsillectomy in children. In adult patients undergoing abdominal surgeries, the use of intravenous lidocaine infusion can prevent POV. OBJECTIVE: To evaluate the anti-emetic effect of an intravenous lidocaine infusion used as an adjuvant to general anaesthesia, in children undergoing elective ear, nose and throat surgery. DESIGN: Double-blind, randomised, controlled study. SETTING: Hospital-based, single-centre study in Chile. PATIENTS: ASA I-II children, aged 2 to 12 years, scheduled for elective tonsillectomy. INTERVENTION: We standardised the induction and maintenance of anaesthesia. Patients were randomly allocated to lidocaine (1.5 mg kg intravenous lidocaine over 5 min followed by 2 mg kg h) or 0.9% saline (at the same rate and volume). Infusions were continued until the end of the surgery. MAIN OUTCOME MEASURES: Presence of at least one episode of vomiting, retching or both in the first 24 h postoperatively (POV). SECONDARY OUTCOMES: Plasma concentrations of lidocaine and postoperative pain. RESULTS: Ninety-two children were enrolled. Primary outcome data were available for 91. In the Lidocaine group, 28 of 46 patients (60.8%) experienced POV, compared with 37 of 45 patients (82.2%) in the Saline group [difference in proportions 21.3% (95% confidence interval (CI) 2.8 to 38.8), P = 0.024]. The intention-to-treat analysis showed that when we assumed that the patient in the Saline group lost to follow-up did not have POV, the difference in proportions decreased to 19.6% (95% CI, 0.9 to 37.2), with an unadjusted odds ratio of 0.38 (95% CI, 0.15 to 0.97, P = 0.044). The odds of having POV were 62% less likely in those patients receiving lidocaine compared with patients in the Saline group. The mean lidocaine plasma concentration was 3.91 µg ml (range: 0.87 to 4.88). CONCLUSION: Using an intravenous lidocaine infusion as an adjuvant to general anaesthesia decreased POV in children undergoing elective tonsillectomy. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01986309.

Ultrasonography for neuraxial blocks: a review of the evidence.

INTRODUCTION: This narrative review summarizes the evidence derived from randomized controlled trials (RCTs) pertaining to the use of adjunctive ultrasonography (US) for neuraxial blocks. EVIDENCE ACQUISITION: The literature search was conducted using the MEDLINE, EMBASE and PUBMED databases. For the MEDLINE and EMBASE searches, the MESH terms "ultrasonography" and key word "ultrasound" were queried; using the operator "and", they were combined with the MESH terms "neuraxial block," "epidural anesthesia," "epidural analgesia," "spinal anesthesia," "spinal analgesia," "intrathecal anesthesia," "intrathecal analgesia," "caudal anesthesia," and "caudal analgesia." For the PUBMED search, the search terms "ultrasound neuraxial," "ultrasound intrathecal," "ultrasound epidural" (limited to clinical trials), "ultrasound spinal" (limited to clinical trials), and "ultrasound caudal" (limited to clinical trials) were queried. Seventeen RCTs were retained for analysis. EVIDENCE SYNTHESIS: Compared to conventional palpation of landmarks, US assistance (i.e., preprocedural scanning) results in fewer needle passes/insertions and skin punctures for neuraxial blocks in obstetrical and surgical patients. These benefits seem most pronounced when expert operators carry out the sonographic exams and for patients displaying difficult spinal anatomy. Preliminary findings also suggest that US provides similar pain relief and functional improvement to fluoroscopy for epidural/caudal steroid injection in patients afflicted with chronic spinal pain. Although one trial demonstrated shorter needling time with US guidance (i.e., real-time scanning of needle advancement) compared to US assistance, these findings require further validation. CONCLUSIONS: Published reports of RCTs provide evidence to formulate limited recommendations regarding the use of adjunctive US for neuraxial blocks. Further well-designed RCTs are warranted.

The effective effect-site propofol concentration for induction and intubation with two pharmacokinetic models in morbidly obese patients using total body weight.

BACKGROUND: Most pharmacokinetic (PK) models used for propofol administration are based on studies in normal-weight patients. Extrapolation of these models for morbidly obese patients is controversial. Using 2 PK models and a target-controlled infusion system, we determined the predicted propofol effect-site concentration (Ce) needed for induction of anesthesia in morbidly obese subjects using total body weight. METHODS: Sixty-six morbidly obese subjects from 18 to 50 years of age were randomized to receive propofol to reach and maintain a predetermined propofol Ce, based on the PK models of either Marsh or Schnider. All patients were monitored with a Bispectral Index electroencephalographic monitor. Fentanyl 3 µg/kg total body weight was administered before starting the propofol infusion. After loss of consciousness, vecuronium was administered to facilitate endotracheal intubation. Groups of 6 patients each received propofol at a different, predetermined target propofol Ce. An "effective Ce" (ECe) was defined as the propofol Ce that provided adequate hypnosis (Bispectral Index <60) during the complete induction period (45 seconds after reaching the predetermined target Ce until 5 minutes after tracheal intubation). Heart rate and arterial blood pressure were measured every 1 minute throughout the study period. Probit regression analysis was performed to calculate the effective propofol Ce values to induce hypnosis in 50% (ECe(50)) and 95% (ECe(95)) of patients with 95% confidence intervals (CIs). RESULTS: Patient characteristics were similar between models and across the propofol target concentration groups. The ECe(50) of propofol was 3.4 µg/mL (95% CI: 2.9, 3.7 µg/mL) with the Marsh model and 4.5 µg/mL (95% CI: 4.1, 4.8 µg/mL) with the Schnider model (P < 0.001). The ECe(95) values were 4.2 µg/mL (95% CI: 3.8, 6.2 µg/mL) and 5.5 µg/mL (95% CI: 5.0, 7.2 µg/mL) with Marsh and Schnider models, respectively. At the ECe(95), hemodynamic effects were similar with the 2 PK models. CONCLUSION: Different propofol target concentrations for each PK model must be used for induction when using total body weight in morbidly obese patients.