Jamie D. Murphy

Analgesic efficacy of ultrasound-guided regional anesthesia: a meta-analysis

STUDY OBJECTIVE To determine if the use of ultrasound guidance (vs non-ultrasound techniques) improves the success rate of nerve blocks. DESIGN Meta-analysis of randomized controlled trials (RCTs) in the published literature. SETTING University medical center. MEASUREMENTS 16 RCTs of patients undergoing elective surgical procedures were studied. Patients underwent ultrasound-guided or non-ultrasound techniques (nerve stimulation, surface landmark) for peripheral nerve blocks. Success rates were measured. MAIN RESULTS Ultrasound guidance (vs all non-ultrasound techniques) was associated with a significant increase in the success rate of nerve blocks [relative risk (RR) = 1.11 (95% confidence interval [CI]: 1.06 to 1.17, P < 0.0001]). When compared with nerve stimulator techniques only, ultrasound guidance was still associated with an increase in the success rate (RR = 1.11 [95% CI: 1.05 to 1.17, P = 0.0001]). For specific blocks, ultrasound guidance (vs all non-ultrasound) was associated with a significant increase in successful brachial plexus (all) nerve blocks (RR = 1.11 [95% CI: 1.05 to 1.20, P = 0.0001]), sciatic popliteal nerve block (RR = 1.22 [95% CI: 1.08 to 1.39, P = 0.002]) and brachial plexus axillary nerve block (RR = 1.13 [95% CI: 1.00 to 1.26, P = 0.05]) but not brachial plexus infraclavicular nerve block (RR = 1.25 [95% CI: 0.88 to 1.76, P = 0.22]). CONCLUSIONS Ultrasound-guided peripheral nerve block is associated with an increased overall success rate when compared with nerve stimulation or other methods. Ultrasound-guided techniques also increase the success rate of some specific blocks.

The role of perioperative high inspired oxygen therapy in reducing surgical site infection: a meta-analysis.

BACKGROUND: The clinical role of hyperoxia for preventing surgical site infection remains uncertain because randomized controlled trials on this topic have reported disparate results. Our objective in this systematic review was to determine whether perioperative hyperoxia reduces surgical site infection. METHODS: An electronic search was conducted using the National Library of Medicines MEDLINE, Cochrane Collaborations CENTRAL, and EMBASE databases. Included studies consisted of randomized controlled trials in an adult population with a clearly defined comparison of high oxygen versus low oxygen or control, and with a documented assessment for perioperative infection. Pooled estimates for odds ratios (ORs) with 95% confidence intervals were obtained for our primary outcome (surgical site infection) using the Cochrane Collaborations RevMan version 5.0.25 (Cochrane Collaboration, Oxford, UK). ORs were calculated using a random effects model. RESULTS: The literature search ultimately yielded 7 trials, enrolling 2728 patients, that were included in the analysis. There were 1358 patients randomly assigned to hyperoxia and 1370 to control. The pooled infection rate in the hyperoxia group was 15.5% versus 17.5% in the control group. Hyperoxia resulted in an OR of 0.85 for surgical site infection (95% confidence interval: 0.52, 1.38) (P = 0.51). However, 2 subgroup analyses (general anesthesia and colorectal surgery trials) showed a benefit for high inspired oxygen therapy of decreasing surgical site infection. CONCLUSIONS: Perioperative high inspired oxygen therapy overall was not found to be beneficial for preventing surgical site infection based on this meta-analysis. The positive results of 2 subgroup analyses (general anesthesia and colorectal surgery trials) suggest a benefit for hyperoxia in decreasing surgical site infection. Additional studies are needed to further investigate this intervention.

Regional techniques and outcome: what is the evidence?

Purpose of review Despite some controversy regarding the strength of the available data, the use of regional anesthesia and analgesia does provide improvement in patient outcomes. Although the majority of available data have examined the effect of epidural anesthesia and analgesia on patient outcomes, an increasing number of studies recently have investigated the effect of peripheral regional techniques on patient outcomes. Recent findings Data generally indicate that the perioperative use of regional anesthesia and analgesia may be associated with improvement in both major (e.g. mortality, major morbidity) outcomes and rehabilitation. The majority of evidence favors an ability of epidural analgesia to reduce postoperative cardiovascular and pulmonary complications and there is also consistent evidence that epidural analgesia with local anesthetics is associated with faster resolution of postoperative ileus after major abdominal surgery. Overall, regional analgesic techniques provide statistically superior analgesia compared with systemic opioids. Summary Perioperative use of regional analgesic techniques may provide improvement in conventional outcomes, although the benefit appears to be limited to high-risk patients and those undergoing high-risk procedures. The benefits conferred by perioperative regional anesthetic techniques need to be weighed against any potential risks and this should be assessed on an individual basis.

Postoperative Pain Management in the Elderly Undergoing Thoracic Surgery

The management of postoperative pain in the elderly represents a considerable challenge because these patients are generally at higher risk for postoperative complications. There are several analgesic options, some of which may influence perioperative morbidity in this high-risk group of patients. Although use of regional analgesia, particularly epidural analgesia is associated with some benefits, including a decrease in perioperative morbidity, there are side effects and complications (eg, medication-related side effects, epidural hematoma, infection) from these and other techniques, and the clinician should evaluate the benefits and risks of each technique on an individual basis. Nevertheless, the available data suggest that use of regional analgesic techniques (ie, epidural and paravertebral catheters) is associated with a decrease in perioperative pulmonary complications.

Methodological Quality of Randomized Controlled Trials of Postoperative Epidural Analgesia Validation of the Epidural Analgesia Trial Checklist as a Specific Instrument to Evaluate Methodology

Background: The overall benefits of epidural analgesia are controversial, in part because of the varying quality of methodology in published randomized controlled trials (RCTs). We performed a systematic review of available RCTs to examine the methodological quality of epidural analgesia trials. Current instruments for evaluating the quality of methodology are generic; thus, we also developed a specific assessment tool named Epidural Analgesia Trial Checklist (EATC). Methods: The National Library of Medicines PubMed database was searched (1966 to January 2006) for RCTs of epidural analgesia. All RCTs that had epidural infusion analgesia in at least 1 study arm and as primary intervention for randomization were included. Two independent reviewers were given blinded full-text paper versions of each article and reviewed all articles for inclusion in this study. Study characteristics were extracted from accepted RCTs, and reviewers completed the standardized 7-item Jadad score, 22-item Consolidated Standards of Reporting Trials (CONSORT) checklist, and 8-item EATC for evaluation of methodological quality. Results: A total of 321 articles met all inclusion criteria. The overall median (first, third quartiles) Jadad, CONSORT, and EATC scores were 2 (1, 3), 10 (8, 11), and 4 (3, 6) (of maximum scores of 5, 22, and 8), respectively. For all assessments, we found significantly higher methodological study quality for articles with a larger study population size, those written by a first author affiliated with an anesthesiology department, and studies published after release of the CONSORT statement with a significant overall increase in methodological quality over time. There was no effect on methodological quality with regard to region of publication or number of centers. There was relatively high interrater agreement when using the EATC (&kgr; = 0.92). The items most frequently lacking from the studies captured using the EATC were appropriate description/definition of adverse effects (11.8% of all studies properly reported this), proper presentation of visual analog scale (VAS) pain scores (31.2%), and assessment of VAS pain both at rest and with activity (39.9%). Conclusions: Methodology scores for epidural analgesia RCTs have improved over time. The EATC seems to correlate well with other commonly used generic assessments for methodological RCT quality and be useful for assessing methodological quality of epidural RCTs. Future epidural analgesia RCTs should focus on improving appropriate description/definition of adverse effects, proper presentation of VAS pain scores, and assessment of VAS pain both at rest and with activity.

Atrial natriuretic peptide production and natriuretic peptide receptors in the human uterus and their effect on myometrial relaxation

OBJECTIVE The objective of the study was to identify the effect of atrial natriuretic peptide (ANP) on uterine contractility, production of ANP, and natriuretic peptide receptor (NPR) expression in human myometrial tissue. STUDY DESIGN In an institutional review board-approved study, gravid human myometrium was obtained from patients undergoing cesarean section. Uterine contractility was examined using isometric force tension studies. After regular uterine contractions were obtained with oxytocin, ANP was added in increasing concentrations. ANP concentration was measured from myometrial tissue using radioimmunoassay (RIA). Primary myometrial cell culture was performed and treated with nifedipine vs oxytocin. RIA was performed on these cells and the cell culture media. Western blot analysis was performed on uterine tissue samples for natriuretic peptide receptors. RESULTS With increasing concentration of ANP (starting at 3 pM), myometrial contraction frequency decreased. ANP was identified in primary cultured myometrial cells and cell culture media. Myometrial ANP concentration increased with advancing gestational age. The concentration of ANP decreased within myometrial cells treated with oxytocin. The amount of ANP in the cell culture media increased from cells treated with nifedipine. Western blot identified NPR-A, -B, and -C in myometrial tissue. NPR-A expression was significantly increased in preterm samples. CONCLUSION ANP has a dose dependent effect on uterine relaxation. ANP is present in human myometrial cells and appears to be secreted by myometrial cells. The concentration of ANP may vary with gestational age and modulators of uterine contractility. NPR-A, -B, and -C receptor proteins are present in myometrial tissue. NPR-A levels may correlate with gestational age.

Evaluation of epidural and peripheral nerve catheter heating during magnetic resonance imaging

Background Many epidural and peripheral nerve catheters contain conducting wire that could heat during magnetic resonance imaging (MRI), requiring removal for scanning. Methods We tested 2 each of 6 brands of regional analgesia catheters (from Arrow International [Reading, Pennsylvania], B. Braun Medical Inc [Bethlehem, Pennsylvania], and Smiths Medical/Portex [Keene, New Hampshire]) for exposure to clinical 1.5- and 3-T MRI. Catheters testing as nonmagnetic were placed in an epidural configuration in a standard human torso–sized phantom, and an MRI pulse sequence applied at the maximum scanner-allowed radiofrequency specific absorption rate (SAR) for 15 minutes. Temperature and SAR exposure were sampled during MRI using multiple fiberoptic temperature sensors. Results Two catheters (the Arrow StimuCath Peripheral Nerve and B. Braun Medical Perifix FX Epidural) were found to be magnetic and not tested further. At 3 T, exposure of the remaining 3 epidural and 1 peripheral nerve catheter to the scanner’s maximum RF exposure elicited anomalous heating of 4°C to 7°C in 2 Arrow Epidural (MultiPort and Flex-Tip Plus) catheters at the entry points. Temperature increases for the other catheters at 3 T, and all catheters at 1.5 T were 1.4°C or less. When normalized to the body-average US Food and Drug Administration guideline SAR of 4 W/kg, maximum projected temperature increases were 0.1°C to 2.5°C at 1.5 T and 0.7°C to 2.7°C at 3 T, except for the Arrow MultiPort Flex-Tip Plus catheter at 3 T whose increase was 14°C. Conclusions Most but not all catheters can be left in place during 1.5-T MRI scans. Heating of less than 3°C during MRI for most catheters is not expected to be injurious. While heating was lower at 1.5 T versus 3 T, performance differences between products underscore the need for safety testing before performing MRI.

The weekend effect in hospitalized patients: A meta-analysis

BACKGROUND: The presence of a “weekend effect” (increased mortality rate during Saturday and/or Sunday admissions) for hospitalized inpatients is uncertain. PURPOSE: We performed a systematic review to examine the presence of a weekend effect on hospital inpatient mortality. DATA SOURCES: PubMed, EMBASE, SCOPUS, and Cochrane databases (January 1966‐April 2013) were utilized for our search. STUDY SELECTION: We examined the mortality rate for hospital inpatients admitted during the weekend compared with those admitted during the workweek. To be included, the study had to provide discrete mortality data around the weekends (including holidays) versus weekdays, include patients who were admitted as inpatients over the weekend, and be published in English. DATA EXTRACTION: The primary outcome was all‐cause weekend versus weekday mortality with subgroup analysis by personnel staffing levels, rates and times to procedures rates and delays, or illness severity. DATA SYNTHESIS: A total of 97 studies (N = 51,114,109 patients) were examined. Patients admitted on the weekends had a significantly higher overall mortality (relative risk, 1.19; 95% confidence interval, 1.14‐1.23). With regard to the subgroup analyses, patients admitted on the weekends consistently had higher mortality than those admitted during the week, regardless of the levels of weekend/weekday differences in staffing, procedure rates and delays, and illness severity. CONCLUSIONS: Hospital inpatients admitted during weekends may have a higher mortality rate compared with inpatients admitted during the weekdays.

The role of perioperative chewing gum on gastric fluid volume and gastric pH: a meta-analysis.

STUDY OBJECTIVE To determine if preoperative gum chewing affects gastric pH and gastric fluid volume. DESIGN Systematic review and meta-analysis. METHODS Data sources included Cochrane, PubMed, and EMBASE databases from inception to June 2012 and reference lists of known relevant articles without language restriction. Randomized controlled trials in which a treatment group that chewed gum was compared to a control group that fasted were included. Relevant data, including main outcomes of gastric fluid volume and gastric pH, were extracted. RESULTS Four studies involving 287 patients were included. The presence of chewing gum was associated with small but statically significant increases in gastric fluid volume (mean difference = 0.21 mL/kg; 95% confidence interval, 0.02-0.39; P = .03) but not in gastric pH (mean difference = 0.11 mL/kg; 95% confidence interval, -0.14 to 0.36; P = .38). Gastric fluid volume and gastric pH remained unchanged in subgroup analysis by either sugar or sugarless gum type. CONCLUSIONS Chewing gum in the perioperative period causes small but statically significant increases in gastric fluid volume and no change in gastric pH. The increase in gastric fluid most likely is of no clinical significance in terms of aspiration risk for the patient. Elective surgery should not necessarily be canceled or delayed in healthy patients who accidentally chew gum preoperatively.

The Analgesic Efficacy of Nonsteroidal Anti-inflammatory Agents (NSAIDs) in Patients Undergoing Cesarean Deliveries: A Meta-Analysis.

Background and Objectives Postoperative pain after cesarean delivery, which accounts for approximately 1 in 3 live births in the United States, can be severe in many patients. Nonsteroidal anti-inflammatory agents (NSAIDs) are potent analgesics that are effective in the treatment of postoperative pain. In this meta-analysis, we assessed the analgesic efficacy of NSAIDs in postoperative cesarean delivery patients. Methods An electronic literature search of the Library of Medicines PubMed, Cochrane CENTRAL, Scopus, and EMBASE databases was conducted in May 2013 and updated in January 2015 (Appendix, Supplemental Digital Content 1, http://links.lww.com-AAP-A174). Searches were limited to randomized controlled trials. The primary outcome variable was visual analog scale or numerical rating scale pain scores. Secondary outcomes included cumulative postoperative opioid consumption and opioid-related adverse effects (drowsiness-sedation, nausea, and vomiting). Data extraction was performed independently by 2 reviewers. Extracted data were input into Review Manager. Results Twenty-two randomized controlled trials compared a NSAID (n = 639) to a control (n = 674). Patients in the NSAID group versus control reported lower pain scores at 12 hours (P = 0.003) and at 24 hours (P < 0.001). Subgroup analysis showed a significant difference in pain scores at 24 hours, with patients receiving NSAIDs via intravenous-intramuscular (P < 0.001) route, but not the oral (P = 0.39) or rectal routes (P = 0.99). Significantly lower average pain scores were reported for pain with movement at 24 hours in the NSAID group (P = 0.001). Patients in the NSAID group versus controls consumed significantly less opioids (P < 0.001) and had significantly less drowsiness-sedation (P = 0.03), but there was no significant difference between the groups with regard to nausea or vomiting (P = 0.48 and P = 0.17, respectively). Conclusions The perioperative use of NSAIDs in cesarean delivery patients will result in a significantly lower pain scores, less opioid consumption, and less drowsiness-sedation but no difference in nausea or vomiting compared to those who did not receive NSAIDs. Further research should address the optimal NSAID regimen and examine the effect of improved analgesia on patient-centered outcomes such as patient satisfaction and quality of breastfeeding.