Search

Mechanomyography is currently the accepted laboratory reference standard for quantitative neuromuscular blockade monitoring. Mechanomyographs are not commercially available. Previously, a mechanomyograph was built by our laboratory and used in several clinical studies. It was subsequently redesigned to improve its usability and functionality and to accommodate a wider range of hand sizes and shapes using an iterative design process. Each version of the redesigned device was initially tested for usability and functionality in the lab with the investigators as subjects without electrical stimulation. The redesigned devices were then assessed on patients undergoing elective surgery under general anesthesia without neuromuscular blocking drugs. Since the patients were not paralyzed, the expected train-of-four ratio was 1.0. The device accuracy and precision were represented by the train-of-four ratio mean and standard deviation. If issues with the device's useability or functionality were discovered, changes were made, and the redesign processes repeated. The final mechanomyograph design was used to collect 2,362 train-of-four ratios from 21 patients. The mean and standard deviation of the train-of-four ratios were 0.99 ± 0.030. Additionally, the final mechanomyograph design was easier to use and adjust than the original design and fit a wider range of hand sizes. The final design also reduced the frequency of adjustments and the time needed for adjustments, facilitating data collection during a surgical procedure. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to compare the Stimpod electromyograph neuromuscular blockade monitor to mechanomyography, which is widely considered to be the reference standard. Methods: The Stimpod electromyograph was used with its designated electrode array on the same hand as the mechanomyograph. Pairs of train-of-four measurements were recorded every 0.5-2 min. When the train-of-four count was zero on the electromyograph monitor, pairs of post tetanic count measurements were recorded every 2.5 min, instead of train-of-four measurements. Measurements were recorded from immediately after induction of anesthesia until just before emergence. Stimulation current was set to 60 mA with a duration of 200 microsec. The mechanomyography recording system recorded each twitch waveform for analysis. High resolution electromyograph waveforms were also recorded using a datalogger accessory provided by the manufacturer, facilitating inspection of individual waveforms. The administration of neuromuscular blocking drugs was left up to the discretion of the anesthesia care team. Results: Twenty-three patients contributed 1,088 data pairs suitable for analysis. Bland-Altman analysis of 415 pairs of train-of-four ratios showed a bias of 0.028 and limits of agreement of -0.18 and 0.24. Two hundred seventy-three train-of-four count data pairs were compared by Cohen's quadratically weighted kappa which was calculated to be 0.44, indicating moderate agreement. Three hundred thirty-eight post tetanic count data pairs were compared by Cohen's quadradically weighted kappa which was calculated to be 0.80, indicating substantial agreement. Conclusion: The electromyograph produced results that were comparable to the mechanomyograph. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare train-of-four count and ratio measurements with the GE electromyograph to the TwitchView electromyograph, that was previously validated against mechanomography, and to palpation of train-of-four count. Electrodes for both monitors were applied to the same arm of patients undergoing an unrestricted general anesthetic. Train-of-four measurements were performed with both monitors approximately every 5 min. In a subset of patients, thumb twitch was palpated by one of the investigators. Eleven patients contributed 807 pairs of train-of-four counts or ratios. A subset of 5 patients also contributed palpated train-of-four counts. Bland-Altman analysis of the train-of-four ratio found a bias of 0.24 in the direction of a larger ratio with the GE monitor. For 72% of data pairs, the GE monitor train-of-four ratios were larger. For 59% of data pairs, the GE monitor train-of-four counts were larger (p < 0.0001). For 11% of data pairs, the GE monitor train-of-four count was 4 when the Twitchview monitor count was zero. When manual palpation of train-of-four count was compared to train-of-four count determined by the monitors, 70% of data pairs were identical between palpation and TwitchView train-of-four count, while 30% of data pairs were identical between palpation and GE train-of-four count. For 7% of data pairs, the GE monitor train-of-four count was 4 when the palpation count was 0. The GE electromyograph may overestimate the train-of-four count and ratio. The GE electromyograph frequently reported 4 twitches when none were actually present due to misinterpretation of artifacts. [ABSTRACT FROM AUTHOR]

Critical patient care information is often omitted or misunderstood during handoffs, which can lead to inefficiencies, delays, and sometimes patient harm. We implemented an aviation-style post-anesthesia care unit (PACU) handoff checklist displayed on a tablet computer to improve PACU handoff communication. We developed an aviation-style computerized checklist system for use in procedural rooms and adapted it for tablet computers to facilitate the performance of PACU handoffs. We then compared the proportion of PACU handoff items communicated before and after the implementation of the PACU handoff checklist on a tablet computer. A trained observer recorded the proportion of PACU handoff information items communicated, any resistance during the performance of the checklist, the type of provider participating in the handoff, and the time required to perform the handoff. We also obtained these patient outcomes: PACU length of stay, respiratory events, post-operative nausea and vomiting, and pain. A total of 209 PACU handoffs were observed before and 210 after the implementation of the tablet-based PACU handoff checklist. The average proportion of PACU handoff items communicated increased from 49.3% (95% CI 47.7-51.0%) before checklist implementation to 72.0% (95% CI 69.2-74.9%) after checklist implementation (p < 0.001). A tablet-based aviation-style handoff checklist resulted in an increase in PACU handoff items communicated, but did not have an effect on patient outcomes. [ABSTRACT FROM AUTHOR]

The PhysioDoloris™ analgesia monitor assesses nociception effects on the autonomic nervous system by analyzing changes in heart rate variability (HRV). This non-invasive device analyses ECG signals and determines the analgesia nociception index (ANI), allowing for quantitative assessment of the analgesia/nociception balance in anesthetized patients. Ketamine, an analgesic adjuvant with sympathomimetic properties, has been shown to improve perioperative pain management. The purpose of this pilot study was to evaluate whether low-dose ketamine, due to its intrinsic effect on the sino-atrial node, affects HRV and, therefore, interferes with ANI measurements. This pilot study included 20 women undergoing abdominal hysterectomies. Anesthesia and analgesia were maintained with sevoflurane and fentanyl respectively, in a standardized manner. Five minutes after intubation, 0.5 μg kg of intravenous (i.v.) ketamine was administered. ANI, bispectral index (BIS), heart rate and blood pressure were recorded from the induction of anesthesia until 5 min after skin incision. There was not any significant decrease in mean (±SD) ANI values after intubation (2.11 ± 20.11, p = 0.35) or i.v. ketamine administration (1.31 ± 15.26, p = 0.28). The mean (±SD) reduction in ANI values after skin incision was statistically significant (13.65 ± 15.44, p = 0.01), which is consistent with increased nociception. A single i.v. bolus of 0.5 μg kg ketamine did not influence the ANI values of 20 women under standardized general anesthesia conditions and absent noxious stimulation. These results suggest that the ANI derived from the PhysioDoloris™ analgesia monitor is feasible under such clinical conditions. [ABSTRACT FROM AUTHOR]

Increased thrombin generation and impaired fibrinolysis during Escherichia coli O157:H7-associated hemolytic uremic syndrome (HUS) plausibly diminish myocardial blood flow, but the frequency of cardiac ischemia during HUS is unknown. We identified a 9-year-old boy with HUS in whom myocardial diastolic dysfunction was demonstrated by echocardiography, who also had elevated serum troponin-I and creatine kinase MB mass. However, eight additional patients with HUS did not have elevated markers of cardiac injury. When present, elevated troponin-I should be considered to represent myocardial injury, and not attributed simply to renal insufficiency. It is possible that myocardial ischemia and secondary arrhythmias account for some sudden deaths that occur during acute HUS. [ABSTRACT FROM AUTHOR]

The role of platelet-activating factor (PAF), a phospholipid inflammatory mediator, in Escherichia coli O157:H7-associated hemolytic uremic syndrome (HUS) is unknown. PAF is synthesized by diverse cells and is degraded by PAF-acetylhydrolase (PAF-AH). Deficient PAF-AH activity results from a G→T transversion at position 994 of exon 9. We examined children infected with E. coli O157:H7 to determine if PAF levels or the PAF-AH (G994T) mutation reflects the risk of developing HUS. Plasma PAF concentrations were determined using chloroform/methanol extraction, thin layer chromatography purification, and scintillation proximity assay in 10 patients with uncomplicated infection (UI), 10 infected patients who subsequently developed HUS (pre-HUS), 5 HUS patients, and 8 healthy controls. The PAF-AH (G994T) allele frequency was determined in 52 UI children, 15 with HUS, and 11 controls. Wilcoxon rank sum tests were performed to test differences in location (median) of pairs of groups. PAF levels were higher in the UI (P=0.04) and pre-HUS (P=0.01) groups than in healthy controls. No subject had the PAF-AH (G994T) allele. Thus, elevated plasma PAF levels occur in E. coli O157:H7-infected children, even without HUS, but diminish when HUS develops. The PAF-AH (G994T) allele does not contribute to the risk of developing HUS. [ABSTRACT FROM AUTHOR]