Hee Jung Baik

We thank Dr. Todd1 for his interest in our article, “Comparison of Contralateral Acceleromyography and Electromyography for Posttetanic Count Measurement.”2 In clinical practice, numerous acceleromyography devices measuring acceleration of muscle movement and recently developed electromyography devices measuring evoked muscle complex action potentials are used for quantitative neuromuscular monitoring. However, anesthesiologists are usually not aware of each device’s algorithms. Moreover, research data, such as comparing agreements between each device and mechanomyography or between each device including a comparison with tactile or visual response of twitch for train-of-four count and ratio or posttetanic count, are very limited. Therefore, this leaves us uncertain as to which equipment is most accurate and suitable for neuromuscular monitoring. Along with previous studies,3–7 our study2 has presented essential and important data in the field of neuromuscular research, and I believe that more similar active studies should be conducted.When comparing devices or comparing devices with the visible or tactile response for the weak response that appears as the twitch response gradually decreases, we totally concur with Dr. Todd’s comment that “a twitch is not always a twitch.” The comparison results may vary, not only between devices using different technologies in the twitch measurement, but also between devices using the same technology with different algorithms by manufacturers.3–8 Therefore, the study results cannot be generalized under the name of acceleromyography or electromyography. Thus, in the conclusion section of our article, the name of the equipment was specified as follows: “In conclusion, this observational study demonstrated that acceleromyography (Philips IntelliVue) frequently counted more twitches than electromyography (TwitchView) in posttetanic count monitoring.” To the best of our knowledge, the software version of the equipment was not specified in previous studies, and Dr. Todd recommends specifying the software versions along with the device names, which are as follows: Philips IntelliVue (software version A.00.10; Philips Healthcare, The Netherlands) and TwitchView (software version 1.0.52; Blink Device Company, USA).Recently, during and after general anesthesia using neuromuscular blocking agents, quantitative neuromuscular monitoring is strongly recommended. The use of quantitative neuromuscular monitors based on various technologies and different algorithms is increasing in clinical practice. Therefore, understanding of the characteristics of each device and consideration of the results of comparative studies among the devices are warranted.Dr. Baik declares no competing interests.

Background: Electromyography has advantages over mechanomyography and acceleromyography. Previously, agreement of the train-of-four counts between acceleromyography and electromyography was found to be fair. The objective of this study was to assess the agreement of posttetanic count including agreement of neuromuscular blockade status (intense block, posttetanic count equal to 0; or deep block, posttetanic count 1 or greater and train-of-four count equal to 0) between acceleromyography and electromyography. Methods: Thirty-six patients, aged 20 to 65 yr, participated in this study. A dose of 0.6 mg/kg rocuronium, with additional dose of 0.3 mg/kg if required, was administered to the patients. The train-of-four and posttetanic counts were monitored in the contralateral arm using electromyography at the first dorsal interosseus or adductor pollicis, and acceleromyography at the adductor pollicis. Posttetanic count measurements were performed at 6-min intervals; the responses were recorded until the train-of-four count reached 1. The authors evaluated the agreement of degree of neuromuscular blockade (intense or deep block) and that of posttetanic count between acceleromyography and electromyography. Results: The authors analyzed 226 pairs of measurements. The percentage agreement indicating the same neuromuscular blockade status (intense or deep block) between acceleromyography and electromyography was 73%. Cohen’s kappa coefficient value was 0.26. After excluding data with acceleromyography–posttetanic counts greater than 15, a total of 184 pairs of posttetanic counts were used to evaluate the agreement between the two monitoring methods. For acceleromyography–posttetanic count, 42 (23%) pairs had the same electromyography–posttetanic count, and 93 (50%) pairs had more than the electromyography–posttetanic count. The mean posttetanic count on electromyography was 38% (95% CI, 20 to 51%) lower than that on acceleromyography (P = 0.0002). Conclusions: Acceleromyography frequently counted more twitches than electromyography in posttetanic count monitoring. Acceleromyography– and electromyography–posttetanic counts cannot be used interchangeably to assess the degree of neuromuscular blockade. Editor’s Perspective: What We Already Know about This Topic: What This Article Tells Us That Is New:

Purpose: The supramaximal stimulation (SMS) of the TOF test causes uncomfortable sensations in patients. We aimed to determine whether the submaximal stimulation would be reliable in TOF tests with reduced painful sensation. Methods: The accelomyography (AMG) and electromyography (EMG) monitor was applied at each arm and general anesthesia was induced and maintained by total intravenous anesthesia. At extubation, we conducted TOF test three times at each of four different currents: SMS, 70% SMS, 50% SMS, and 30% SMS. The same procedure was performed in the postanesthesia care unit (PACU) only with EMG, and the pain scores on the numerical rating scale (NRS) during the tests were recorded. Results: A total of 36 patients were enrolled. At extubation, TOF ratios with SMS in AMG and EMG were 112.0 ± 13.1% and 93.7 ± 8.9%, respectively. There were no significant differences in TOF ratios between the SMS and lower stimulation intensities. However, 30% and 50% SMS showed significantly higher rates of the unmeasurable results of tests in the PACU. In terms of the stimulation pain, NRS showed a downward pattern as the current decreased and was significantly lower at 50% and 30% SMS than the NRS at SMS. Conclusion: The TOF test with submaximal stimulation is still reliable and can reduce stimulation pain. Considering the importance of the TOF results in determining extubation, the authors suggest the minimal current for the TOF test as 70% SMS.

The aim of this study is to compare the effects of neuromuscular blockade (NMB) on phase lag entropy (PLE) and the bispectral index (BIS). We recorded the BIS, electromyograph (EMG) activity on a BIS monitor (EMG_BIS), PLE, and EMG activity on a PLE monitor (EMG_PLE) in 40 patients receiving general anesthesia. During the awake state, we analyzed the changes in parameters before and 2 min after the eyes were closed. During sedation, we compared the changes in the parameters before and at 4 min after injecting rocuronium (group R) or normal saline (group C) between the two groups. During anesthesia, we compared the changes in parameters before and at 4 min after injecting sugammadex (group B) or normal saline (group D) between the two groups. During the awake state, the BIS, EMG_BIS, and EMG_PLE, but not PLE, decreased significantly with closed eyes. An effect of EMG on the BIS was evident, but not on PLE. During sedation, the BIS decreased with the decrease in EMG_BIS regardless of NMB caused by rocuronium, but NMB decreased PLE, although the degree of the decrease in EMG_PLE after NMB was similar to that after placebo. To determine the effect of NMB on electroencephalograms (EEGs) in groups R and C, we plotted the power spectra before and at 4 min after injecting rocuronium or normal saline. Changes in slow and delta frequency bands were observed at 4 min after injecting rocuronium relative to before injecting rocuronium. There was no effect of EMG on either the BIS or PLE during anesthesia. In conclusion, the effect of electromyograph activity and/or neuromuscular blockade on BIS or PLE depends on the level of consciousness.

Purpose: In pediatric patients, the most common reason for delaying surgical intervention is an upper respiratory tract infection (URI). To date, there has been no consensus regarding the optimal timeframe for deferring surgery in children with URI. We conducted this study to evaluate whether a URI symptom-free period and other risk factors affect the incidence of perioperative respiratory adverse events (RAEs). Patients and Methods: The study population included 267 pediatric patients (aged 0 to 13 years) with a recent URI episode who underwent surgery under general anesthesia. Following a retrospective review of medical records, several risk factors including a URI symptom-free period for intra- and postoperative RAEs were analyzed using univariate and multivariate logistic regression analyses. Results: RAEs occurred in 23 of 267 patients (8.6%). Univariate analysis revealed that abnormal preoperative chest images (odds ratio [OR], 7.48; 95% confidence interval [CI], 2.46– 22.68, p < 0.001) and emergency operations (OR, 2.84; 95% CI, 1.03– 7.81, p = 0.04) were associated with RAEs. Four variables (abnormal preoperative chest images, emergency operations, age under 1 year and symptom-free period of 7– 13 days) with a significance of < 0.20 in the univariate logistic regression analysis were selected as candidate risk factors for the multivariate model. Among the four variables, abnormalities in preoperative chest images (OR, 7.60; 95% CI, 2.28– 25.3, p = 0.001) and a symptom-free period of 7– 13 days (OR, 0.13; 95% CI, 0.02– 0.88, p = 0.04) were independently associated with RAEs in multivariate logistic regression analysis. Conclusion: For pediatric patients who require surgery and have a recent history of URI, procedures should be performed after a URI symptom-free period of at least 1– 2 weeks. Confirming the absence of abnormalities in preoperative chest images can reduce the incidence of perioperative RAEs.

Rationale: Extracorporeal membrane oxygenation (ECMO) in multiple trauma patients with post-traumatic respiratory failure can be quite challenging because of the need for systemic anticoagulation, which may lead to excessive bleeding. In the last decade, there is a growing body of evidence that veno-venous ECMO (VV-ECMO) is lifesaving in multiple trauma patients with acute respiratory distress syndrome, thanks to technical improvements in ECMO devices. Patient concerns: We report a case of a 17-year-old multiple trauma patient who was drunken and had confused mentality. Diagnoses: She was suffered from critical respiratory failure (life-threatening hypoxemia and severe hypercapnia/acidosis lasting for 70 minutes) accompanied by cardiac arrest and trauma-induced coagulopathy during general anesthesia. Interventions: We decided to start heparin-free VV-ECMO after cardiac arrest considering risk of hemorrhage. Outcomes: She survived with no neurologic sequelae after immediate treatment with heparin-free VV-ECMO. Lessons: Heparin-free VV-ECMO can be used as a resuscitative therapy in multiple trauma patients with critical respiratory failure accompanied by coagulopathy. Even in cases in which life-threatening hypoxemia and severe hypercapnia/acidosis last for >1 hours during CPR for cardiac arrest, VV-ECMO could be considered a potential lifesaving treatment.

Youn Young Lee, Heeseung Lee, Hahck Soo Park, Won Joong Kim, Hee Jung Baik, and Dong Yeon Kim. Anesth Pain Med 2019;14:393-400. https://doi.org/10.17085/apm.2019.14.4.393

BACKGROUND The appropriate level of positive end-expiratory pressure (PEEP) during intra-operative mechanical ventilation remains unclear. OBJECTIVE The aim of this study was to investigate the effects of different levels of PEEP with low tidal volume (low-V_T) ventilation in a steep Trendelenburg position (30°) and pneumoperitoneum on oxygenation, respiratory mechanics and ventilation distribution using electrical impedance tomography. DESIGN A randomised controlled trial. SETTING Single university secondary care centre, conducted from January 2017 to December 2017. PATIENTS Forty female patients, aged 20 to 60 years, and of American Society of Anesthesiologists’ (ASA) physical status 1 or 2, undergoing elective robotic gynaecological surgery were included. INTERVENTION Forty patients were allocated randomly to a PEEP4 (PEEP 4 cmH₂O) group or a PEEP8 (PEEP 8 cmH₂O) group. MAIN OUTCOME MEASURES The primary outcomes were respiratory mechanics. The secondary outcomes included changes in ventilation distribution across the ventral and dorsal regions of interest and postoperative pulmonary complications (PPCs) using a modified clinical pulmonary infection score. RESULTS There was no difference in PaO₂ at any time point. The peak inspiratory pressure (PIP) and mean airway pressure (MP_AW) of the PEEP4 group were lower than those of the PEEP8 group (P < 0.001). The oxygenation factor in the PEEP4 group was higher than that in the PEEP8 group during mechanical ventilation at all times. There was no difference in the fractional distribution of end-expiratory ventilation according to region of interest between the two groups. CONCLUSION Both 4 and 8 cmH₂O of PEEP with low-V_T ventilation can be used for robotic gynaecological surgery that requires a steep Trendelenburg position and pneumoperitoneum. However, 8 cmH₂O of PEEP had no benefit over 4 cmH₂O of PEEP with respect to oxygenation and improvement of dorsal regional ventilation. TRIAL REGISTRATION The trial was registered at the Clinical Trial Registry of Korea (KCT0002255). https://cris.nih.go.kr

The reliability of pulse pressure variation (PPV) and stroke volume variation (SVV) is controversial under pneumoperitoneum. In addition, the usefulness of these indices is being called into question with the increasing adoption of lung-protective ventilation using low tidal volume (VT) in surgical patients. A recent study indicated that changes in PPV or SVV obtained by transiently increasing VT (VT challenge) accurately predicted fluid responsiveness even in critically ill patients receiving low VT. We evaluated whether the changes in PPV and SVV induced by a VT challenge predicted fluid responsiveness during pneumoperitoneum. We performed an interventional prospective study in patients undergoing robot-assisted laparoscopic surgery in the Trendelenburg position under lung-protective ventilation. PPV, SVV, and the stroke volume index (SVI) were measured at a VT of 6 mL/kg and 3 min after increasing the VT to 8 mL/kg. The VT was reduced to 6 mL/kg, and measurements were performed before and 5 min after volume expansion (infusing 6% hydroxyethyl starch 6 ml/kg over 10 min). Fluid responsiveness was defined as ≥15% increase in the SVI. Twenty-four of the 38 patients enrolled in the study were responders. In the receiver operating characteristic curve analysis, an increase in PPV > 1% after the VT challenge showed excellent predictive capability for fluid responsiveness, with an area under the curve (AUC) of 0.95 [95% confidence interval (CI), 0.83–0.99, P < 0.0001; sensitivity 92%, specificity 86%]. An increase in SVV > 2% after the VT challenge predicted fluid responsiveness, but showed only fair predictive capability, with an AUC of 0.76 (95% CI, 0.60–0.89, P < 0.0006; sensitivity 46%, specificity 100%). The augmented values of PPV and SVV following VT challenge also showed the improved predictability of fluid responsiveness compared to PPV and SVV values (as measured by VT) of 6 ml/kg. The change in PPV following the VT challenge has excellent reliability in predicting fluid responsiveness in our surgical population. The change in SVV and augmented values of PPV and SVV following this test are also reliable. This trial was registered with Clinicaltrials.gov, NCT03467711 , 10th March 2018.