Mohamed Tiouririne

Effect of intravenous lidocaine on postoperative recovery of patients undergoing mastectomy: a double-blind, placebo-controlled randomized trial.

Background One of the modalities of treatment for breast cancer surgery pain is opioids, and opioids are associated with adverse effects such as itching and postoperative nausea and vomiting (PONV). Intravenous (IV) lidocaine has been shown to reduce opioid consumption and to improve overall postoperative outcomes in abdominal surgery. In this study, we tested the effect of intraoperative IV lidocaine infusion on the quality of postoperative recovery after breast cancer surgery. Methods Seventy-one patients undergoing breast cancer surgery were randomly assigned to receive either placebo (group P; n = 34) or IV lidocaine (group L; n = 37, bolus 1.5 mg/kg at induction, then infusion at 2 mg/kg/h, stopped 2 hours after the end of surgery) in a prospective double-blind design. Intraoperative and postoperative morphine consumption was calculated. Postoperative pain scores, PONV, and fatigue were assessed at 2, 24, and 48 hours after surgery. Duration of postoperative hospital stay was recorded. Results Demographics were the same between the groups. There was no statistically significant difference in intraoperative or postoperative morphine consumption (P = 0.188 and P = 0.758) between groups. Overall pain scores either at rest or activity (P = 0.348 and P = 0.810, respectively), PONV (P = 0.350), fatigue (P = 0.758), or duration of postoperative hospital stay (P = 0.218) were not statistically different. Conclusions Our findings did not show a significant effect of IV lidocaine during breast cancer surgery on opioid consumption, pain score, PONV, or fatigue, indicating that the benefit of this approach does not generalize across all types of surgery.

Aspiration Prophylaxis and Rapid Sequence Induction for Elective Cesarean Delivery: Time to Reassess Old Dogma?

Aspiration of gastric contents is a rare but feared and potentially fatal complication of anesthesia. In Mendelson’s landmark article on the pathophysiology of pulmonary aspiration in obstetric patients, he recognized that the clinical presentation is different depending on whether the aspirate is solid or liquid. Solid material resulted in suffocation and death, whereas liquid material resulted in “asthma-like” symptoms. Subsequently, he not only demonstrated that lung injury is secondary to gastric acid but also made 2 critical observations: gastric emptying time is delayed during labor, and aspiration occurs when airway reflexes are obtunded by anesthesia. Since 1946, these observations have been considered valid for every parturient who presents for labor and delivery; however, a question arises when caring for the fasted patient who presents for elective cesarean delivery. Does she have the same risk of aspiration as her laboring counterpart? We suggest that she may not be at as high risk as previously thought. This issue emerged when we cared for a primigravida with cardiomyopathy, severe global biventricular hypokinesis, and a left ventricular ejection fraction of 20%. Our decision to proceed with general anesthesia forced us to confront the issue of airway management. Traditional and contemporary teaching considers all obstetric patients to be at increased risk for pulmonary aspiration compared with patients scheduled for nonobstetric elective surgical procedures, mandating pharmacological prophylaxis as well as rapid sequence induction of anesthesia with cricoid pressure. However, the requirements of a patient at risk for aspiration are difficult to reconcile with a judicious, titrated induction of anesthesia that is ideal for a patient with severely compromised cardiac function. Faced with this choice, we opted for a careful induction of anesthesia with mask ventilation before endotracheal intubation, omitting cricoid pressure. This case made us reconsider long-held beliefs about the risk of aspiration in a subset of obstetric patients and specifically ask ourselves whether an appropriately fasted patient presenting for elective cesarean delivery is indeed at increased risk for aspiration compared with patients scheduled for non-obstetric elective procedures. Defining the full stomach has proven difficult. Many investigators have shown that lung injury increases markedly when the pH of the aspirate is 3. The oft-quoted threshold values for defining a full stomach and increased risk of aspiration are gastric volume 0.4 mL/kg with a pH 2.5. These data come from an experiment in a single rhesus monkey in which the investigators directly instilled liquid of varying volumes and acidity into the mainstem bronchus. Lung injury occurred with a volume 0.4 mL/kg and a pH 2.5. This experiment has led to considerable confusion about gastric volume and the risk of aspiration. The authors defined only the amount of aspirate necessary to cause lung injury if the pH was suitably low. The value 0.4 mL/kg has been erroneously interpreted as the amount of gastric volume that puts a patient at risk of aspiration when in fact it is the volume that produced lung injury in a highly contrived laboratory experiment. The more important question is what amount of gastric volume results in regurgitation. Animal data suggest that the residual gastric volume required to produce regurgitation under general anesthesia is much larger than 0.4 mL/kg. As the volume of liquid gastric contents increases, the risk of regurgitation also increases. At some currently unknown volume, this risk may become unacceptably high. There is, however, much evidence showing that if gastric emptying is normal and patients are appropriately fasted, the risk of significant aspiration is extremely low. The critical question to be answered is whether obstetric patients have normal gastric emptying. Mendelson studied laboring patients whom he correctly identified as having delayed gastric emptying. Since then, delayed gastric emptying has frequently been attributed to all obstetric patients. The presumed mechanisms are a hormonally induced decrease in gastric motility and the mechanical and anatomic effect of cephalad displacement of the stomach with distortion of the gastroesophageal From the Department of Anesthesiology, University of Virginia, Charlottesville, Virginia.

The effects of transducer geometry on artifacts common to diagnostic bone imaging with conventional medical ultrasound

The portability, low cost, and non-ionizing radiation associated with medical ultrasound suggest that it has potential as a superior alternative to X-ray for bone imaging. However, when conventional ultrasound imaging systems are used for bone imaging, clinical acceptance is frequently limited by artifacts derived from reflections occurring away from the main axis of the acoustic beam. In this paper, the physical source of off-axis artifacts and the effect of transducer geometry on these artifacts are investigated in simulation and experimental studies. In agreement with diffraction theory, the sampled linear-array geometry possessed increased off-axis energy compared with single-element piston geometry, and therefore, exhibited greater levels of artifact signal. Simulation and experimental results demonstrated that the lineararray geometry exhibited increased artifact signal when the center frequency increased, when energy off-axis to the main acoustic beam (i.e., grating lobes) was perpendicularly incident upon off-axis surfaces, and when off-axis surfaces were specular rather than diffusive. The simulation model used to simulate specular reflections was validated experimentally and a correlation coefficient of 0.97 between experimental and simulated peak reflection contrast was observed. In ex vivo experiments, the piston geometry yielded 4 and 6.2 dB average contrast improvement compared with the linear array when imaging the spinous process and interlaminar space of an animal spine, respectively. This work indicates that off-axis reflections are a major source of ultrasound image artifacts, particularly in environments comprising specular reflecting (i.e., bone or bonelike) objects. Transducer geometries with reduced sensitivity to off-axis surface reflections, such as a piston transducer geometry, yield significant reductions in image artifact.

Does Ondansetron Modify Sympathectomy Due to Subarachnoid Anesthesia?: Meta-analysis, Meta-regression, and Trial Sequential Analysis.

Background:Disagreement among many underpowered studies has led to an equivocal understanding of the efficacy of the 5-HT3 antagonist ondansetron in preventing the consequences of sympathectomy after subarachnoid anesthesia. The authors assessed the efficacy of ondansetron with respect to the overall quality and statistical power of the meta-analyses. Methods:The authors used a standard and a newer method of meta-analysis, trial sequential analysis (TSA), to estimate adjusted CIs based on how much information has been accrued. They also used random-effects meta-analyses techniques, small trial bias assessment, selection models, sensitivity analyses, and the Grading of Recommendations on Assessment, Development, and Evaluation system. These results from the aforementioned techniques were compared, and importance of consideration of these factors was discussed. Results:Fourteen randomized placebo-controlled trials (1,045 subjects) were identified and analyzed. By using conventional meta-analyses, the authors determined that ondansetron was associated with reduction in the incidence of hypotension (relative risk = 0.62 [95% CI, 0.46 to 0.83], P = 0.001; TSA-adjusted CI, 0.34 to 1.12; I2 = 60%, P = 0.002) and bradycardia (relative risk = 0.44 [95% CI, 0.26 to 0.73], P = 0.001; TSA-adjusted CI, 0.05 to 3.85; I2 = 0%, P = 0.84). However, the authors found indications of bias among these trials. TSAs demonstrated that the meta-analysis lacked adequate information size and did not achieve statistical significance when adjusted for sparse data and repetitive testing. The Grading of Recommendations on Assessment, Development, and Evaluation system showed that the results had low to very low quality of evidence. Conclusions:The analyses fail to confirm evidence that ondansetron reduces the incidence of hypotension and bradycardia after subarachnoid anesthesia due to the risk of bias and information sizes less than the required. As results from meta-analysis are given significant weight, it is important to carefully evaluate the quality of the evidence that is input.

Ondansetron Does Not Attenuate Hemodynamic Changes in Patients Undergoing Elective Cesarean Delivery Using Subarachnoid Anesthesia: A Double-Blind, Placebo-Controlled, Randomized Trial.

Introduction Hypotension is the most common complication after subarachnoid anesthesia for cesarean delivery. Several therapeutic and preventive measures are used to attenuate this side effect. Serotonin receptor–blocking drugs have been suggested as one such approach. We sought to determine whether prophylactically administered intravenous ondansetron could attenuate hypotension in patients undergoing elective cesarean delivery performed under subarachnoid anesthesia. Methods Eighty-six patients undergoing elective cesarean delivery were recruited and randomly allocated to receive either 8 mg intravenous ondansetron (group O; n = 44) or placebo (group P; n = 42) in a prospective double-blind design. Systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP), and heart rate (HR) were measured at baseline and at 3-minute intervals from the time of initiation of subarachnoid anesthesia until delivery. Ondansetron effect on hemodynamics (SBP, DBP, MAP, and HR) was quantified and analyzed using a linear mixed effect model. Results We did not find differences in SBP (P = 0.78), MAP (P = 0.89), DBP (P = 0.82), or HR (P = 0.18) between the 2 groups during the study period. Phenylephrine requirements to treat hypotension were 350 &mgr;g (175–700 &mgr;g) in group O and 450 &mgr;g (300–700 &mgr;g) in group P (P = 0.30). The incidence of pruritus was 63% (n = 28 of 44) in group O and 56% (n = 23 of 42) in group P (difference, 0.08 [95% confidence interval, −0.23 to 0.41], P = 0.59). No difference in the incidence of nausea and vomiting or sensory level was found. Conclusions Ondansetron premedication does not attenuate hemodynamic changes after subarachnoid anesthesia nor does it reduce the amount of vasopressor use, pruritus, or nausea and vomiting.

Handheld Real-Time Volumetric Imaging of The Spine: Technology Development

Abstract Technical difficulties, poor image quality and reliance on pattern identifications represent some of the drawbacks of two-dimensional ultrasound imaging of spinal bone anatomy. To overcome these limitations, this study sought to develop real-time volumetric imaging of the spine using a portable handheld device. The device measured 19.2 cm × 9.2 cm × 9.0 cm and imaged at 5 MHz centre frequency. 2D imaging under conventional ultrasound and volumetric (3D) imaging in real time was achieved and verified by inspection using a custom spine phantom. Further device performance was assessed and revealed a 75-min battery life and an average frame rate of 17.7 Hz in volumetric imaging mode. The results suggest that real-time volumetric imaging of the spine is a feasible technique for more intuitive visualization of the spine. These results may have important ramifications for a large array of neuraxial procedures.

Anesthetic Management of Parturients With a Fontan Circulation A Review of Published Case Reports

Parturients with Fontan physiology provide unique and complex challenges to anesthesiologists. Such challenges include the maintenance of a perfect balance between preload, pulmonary vascular resistance, afterload, and cardiac output in a setting of a single ventricle physiology. The physiological changes of pregnancy add additional burden to an already “fragile” physiology, making the anesthetic management for labor and/or cesarean delivery even more complex. Understanding the impact of these changes on the Fontan physiology and the effect of anesthetic choices on this dyad (pregnancy–Fontan) is an imperative prior to caring for these patients. In an effort to determine how these patients are best managed for labor and/or cesarean delivery, we have reviewed the literature examining the peripartum anesthetic management of parturients with Fontan circulation and have identified 27 case reports.

Perioperative Morphine and Cancer Recurrence

There is growing evidence suggesting that certain interventions during the perioperative period may have an impact on long-term outcomes of patients undergoing cancer surgery. It has been postulated that regional anesthetic techniques and other targeted interventions could decrease the risk of cancer recurrence, therefore increasing the disease-free interval and overall survival, of those patients undergoing cancer surgery. Conversely, however, it has also been theorized that volatile anesthetics, opioids and surgery itself are directly or indirectly linked to cancer recurrence. Among the opioids used during the perioperative period, morphine has raised most of the concerns regarding its putative effects on cancer. Indeed, morphine has been found to affect many cellular and cell signaling pathways involved in cancer genesis and possibly causing tumor growth. This chapter will focus on the role of the perioperative period on cancer progression, the recognized mechanisms of action of morphine on cancer and alternative pain management options for patients undergoing cancer surgery.

Imaging Performance of a Handheld Ultrasound System With Real-time Computer-aided Detection of Lumbar Spine Anatomy: A Feasibility Study.

Objectives The aim of this study was to evaluate the imaging performance of a handheld ultrasound system and the accuracy of an automated lumbar spine computer-aided detection (CAD) algorithm in the spines of human subjects. Materials and Methods This study was approved by the institutional review board of the University of Virginia. The authors designed a handheld ultrasound system with enhanced bone image quality and fully automated CAD of lumbar spine anatomy. The imaging performance was evaluated by imaging the lumbar spines of 68 volunteers with body mass index between 18.5 and 48 kg/m2. The accuracy, sensitivity, and specificity of the lumbar spine CAD algorithm were assessed by comparing the algorithms results to ground-truth segmentations of neuraxial anatomy provided by radiologists. Results The lumbar spine CAD algorithm detected the epidural space with a sensitivity of 94.2% (95% confidence interval [CI], 85.1%–98.1%) and a specificity of 85.5% (95% CI, 81.7%–88.6%) and measured its depth with an error of approximately ±0.5 cm compared with measurements obtained manually from the 2-dimensional ultrasound images. The spine midline was detected with a sensitivity of 93.9% (95% CI, 85.8%–97.7%) and specificity of 91.3% (95% CI, 83.6%–96.9%), and its lateral position within the ultrasound image was measured with an error of approximately ±0.3 cm. The bone enhancement imaging mode produced images with 5.1- to 10-fold enhanced bone contrast when compared with a comparable handheld ultrasound imaging system. Conclusions The results of this study demonstrate the feasibility of CAD for assisting with real-time interpretation of ultrasound images of the lumbar spine at the bedside.

Evaluation of high-risk obstetric patients: a survey of US academic centers

STUDY OBJECTIVES Obstetric anesthesiologists commonly care for high-risk obstetric patients. However, it is unclear how obstetricians refer these patients for anesthetic evaluation and whether obstetric anesthesia clinics (OACs) are used. Our study aims were to determine the availability and characteristics of OACs at US academic obstetric centers and to evaluate how high-risk patients are referred for anesthetic evaluation. DESIGN This is a survey study design. SETTING University of Virginia Center for Survey Research. INTERVENTION A survey questionnaire was constructed and electronically mailed to obstetric anesthesia directors based at hospitals with accredited anesthesia residency programs. MEASUREMENT One hundred thirteen obstetric anesthesia directors were contacted. We asked questions about the presence and operational characteristics of OACs. These characteristics were compared between hospitals with high, medium, and low annual delivery volumes. We also inquired about how high-risk patients are referred for anesthetic evaluation. Frequencies were compared using Fisher test, with P< .05 considered as statistically significant. MAIN RESULTS The survey response rate was 58% (n = 65). Overall, only 25 (38%) respondents indicated that their hospital operated an OAC. The proportion of hospitals with an OAC and OAC operational hours did not significantly vary according to hospital delivery volume. Among hospitals with an OAC, 24% respondents indicated that obstetricians always refer high-risk patients to the OAC. Nearly half of respondents (44%) indicated that high-risk patients usually or sometimes receive their first anesthetic evaluation during the delivery hospitalization. CONCLUSION Our findings suggest that, among US academic centers, OACs are uncommon and the referral of high-risk patients for antenatal anesthetic evaluation is inconsistent. These findings suggest that more structured referral processes are needed to ensure that high-risk women receive anesthetic evaluation before labor or delivery.