Analgesia in Major Abdominal Surgery No abstract available

The Clinical Use of Cricoid Pressure: First, Do No Harm Application of cricoid pressure (CP) during rapid sequence induction and intubation sequence has been a “standard” of care for many decades, despite limited scientific proof of its efficacy in preventing pulmonary aspiration of gastric contents. While some of the current rapid sequence induction and intubation guidelines recommend its use, other international guidelines do not, and many clinicians argue that there is insufficient evidence to either continue or abandon its use. Recently published articles and accompanying editorials have reignited the debate on the efficacy and safety of CP application and have generated multiple responses that pointed out the various (and significant) limitations of the available evidence. Thus, a critical discussion of available data must be undertaken before making a final clinical decision on such an important patient safety issue. In this review, the authors will take an objective look at the available scientific evidence about the effectiveness and safety of CP in patients at risk of pulmonary aspiration of gastric contents. We suggest that current data are inadequate to impose clinical guidelines on the use of CP because we acknowledge that currently there is not, and there may never be, a method to prevent aspiration in all patients. In addition, we reiterate that a universally accepted medical-legal standard for approaching the high-risk aspiration patient does not exist, discuss the differences in practice between the US and international practitioners regarding use of CP, and propose 5 recommendations on how future studies might be designed to obtain optimal scientific evidence about the effectiveness and safety of CP in patients at risk for pulmonary aspiration. Accepted for publication June 27, 2019. Funding: None. Conflicts of Interest: See Disclosures at the end of the article. Reprints will not be available from the authors. Address correspondence to Sorin J. Brull, MD, FCARCSI (Hon), Department of Anesthesiology and Perioperative Medicine, Mayo Clinic College of Medicine and Science, 4500 San Pablo Rd, Jacksonville, FL 32224. Address e-mail to sjbrull@me.com. © 2019 International Anesthesia Research Society

To Infinity and Beyond: The Past, Present, and Future of Tele-Anesthesia Because the scope of anesthesia practice continues to expand, especially within the perioperative domain, our specialty must continually examine technological services that allow us to provide care in innovative ways. Telemedicine has facilitated the remote provision of medical services across many different specialties, but it remains somewhat unclear whether the use of telemedicine would fit within the practice of anesthesiology on a consistent basis. There have been several reports on the successful use of telemedicine within the preoperative and intraoperative realm. However, patient selection, patient and provider satisfaction, case cancellation rates, equipment reliability, and security of protected health information are just some of the issues that require further examination. This article seeks to review comprehensively the available literature related to the use of telemedicine within the preoperative, intraoperative, and postoperative phases of anesthetic care as well as analyze the major hurdles often encountered when implementing a teleconsultation service. Security of connection, data storage and encryption, federal and state medical licensure compliance, as well as overall cost/savings analysis are a few of the issues that warrant further exploration and research. As telemedicine programs develop within the perioperative arena, it is imperative for institutions to share knowledge, successes, and pitfalls to improve the delivery of care in today’s technology-driven medical landscape. Accepted for publication June 21, 2019. Funding: None. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Kathryn Harter Bridges, MD, Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, 25 Courtenay Dr, Suite 4200, MSC 240, Charleston, SC 29425. Address e-mail to bridgek@musc.edu. © 2019 International Anesthesia Research Society

Epigenetics Mechanisms in Multiorgan Dysfunction Syndrome Epigenetic mechanisms including deoxyribonucleic acid (DNA) methylation, histone modifications (eg, histone acetylation), and microribonucleic acids (miRNAs) have gained much scientific interest in the last decade as regulators of genes expression and cellular function. Epigenetic control is involved in the modulation of inflammation and immunity, and its dysregulation can contribute to cell damage and organ dysfunction. There is growing evidence that epigenetic changes can contribute to the development of multiorgan dysfunction syndrome (MODS), a leading cause of mortality in the intensive care unit (ICU). DNA hypermethylation, histone deacetylation, and miRNA dysregulation can influence cytokine and immune cell expression and promote endothelial dysfunction, apoptosis, and end-organ injury, contributing to the development of MODS after a critical injury. Epigenetics processes, particularly miRNAs, are emerging as potential biomarkers of severity of disease, organ damage, and prognostic factors in critical illness. Targeting epigenetics modifications can represent a novel therapeutic approach in critical care. Inhibitors of histone deacetylases (HDCAIs) with anti-inflammatory and antiapoptotic activities represent the first class of drugs that reverse epigenetics modifications with human application. Further studies are required to acquire a complete knowledge of epigenetics processes, full understanding of their individual variability, to expand their use as accurate and reliable biomarkers and as safe target to prevent or attenuate MODS in critical disease. Accepted for publication June 5, 2019. Funding: None. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Ettore Crimi, MD, Department of Anesthesiology and Critical Care Medicine, Ocala Health, 1431 SW 1st Ave, Ocala, FL 34478. Address e-mail to ettore.crimi@shcr.com. © 2019 International Anesthesia Research Society

Characterization of the Rapid Drop in Pulse Oximetry Reading After Intraoperative Administration of Methylene Blue in Open Thoracoabdominal Aortic Repairs This study evaluates the changes of oxygen saturation (SpO2) after intravenous administration of methylene blue in 103 patients undergoing open repair of thoracoabdominal aortic aneurysms. We found that SpO2 decreased by a median (interquartile range [IQR]) of 49% (37%–81%) <1 minute after methylene blue administration and recovered completely after approximately 6 minutes—median (IQR) of 270 seconds (180–510). A shorter time to nadir SpO2 was associated with a higher nadir (Spearman r [95% confidence interval {CI}], −0.32 [−0.50 to −0.13]; P = .001). Body surface area (BSA) was positively correlated with nadir SpO2 (Spearman r [95% CI], 0.36 [0.15–0.51]; P < .001). Accepted for publication April 5, 2019. Funding: None. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Lisa Q. Rong, MD, Department of Anesthesiology, Weill Cornell Medicine, 525 E 68th St, M324, New York, NY. Address e-mail to lir9065@med.cornell.edu © 2019 International Anesthesia Research Society

Preoperative Vancomycin Administration for Surgical Site Prophylaxis: Plasma and Soft-Tissue Concentrations in Pediatric Neurosurgical and Orthopedic Patients BACKGROUND: Vancomycin is used for antibiotic prophylaxis in pediatric surgical patients without a complete understanding of plasma and soft-tissue pharmacokinetics. Guidelines recommend incision within 60 minutes after administration; however, tissue vancomycin concentrations at that early time may not be therapeutic. We conducted a study of plasma and skin concentrations in pediatric neurosurgical and orthopedic patients to characterize intraoperative vancomycin pharmacokinetics. METHODS: Patients (0.1–18.8 years of age) undergoing posterior spinal fusion (n = 30) or ventriculoperitoneal shunt placement (n = 30) received intravenous vancomycin 15 mg/kg (maximum 1000 mg) over 1 hour. Skin was biopsied at incision and skin closure. Blood samples were collected at incision, at 2 and 4 hours intraoperatively, and at closure. Population pharmacokinetic analysis was performed to characterize pharmacokinetic parameter estimates and to develop a model of intraoperative plasma and skin vancomycin concentrations versus time. RESULTS: Pharmacokinetic analysis included data from 59 subjects, 130 plasma samples, and 107 skin samples. A 2-compartment model, volume of the central (Vc) and volume of the peripheral compartment (V2), proved to have the best fit. Stepwise covariate selection yielded a significant relationship for body surface area on elimination clearance and body weight on V2. Skin vancomycin concentrations rose continuously during surgery. Modeling predicted that equilibration of skin and plasma vancomycin concentrations took ≥5 hours. CONCLUSIONS: Skin vancomycin concentrations immediately after a preoperative dose are relatively low compared with concentrations at the end of surgery. It may be advisable to extend the time between dose and incision if higher skin concentrations are desired at the start of surgery. Accepted for publication June 13, 2019. Funding: This work was supported by National Institutes of Health (NIH)/National Center for Advancing Translational Sciences (NCATS) Colorado Clinical and Translational Science Awards (CTSA) Grant Number UL1 TR001082, Division of Pediatric Anesthesiology/Department of Anesthesiology University of Colorado, Department of Orthopedics University of Colorado, and Department of Neurosurgery University of Colorado. The authors declare no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (www.anesthesia-analgesia.org). Clinical Trial Number and Registry URL: National Clinical Trial (NCT) 03453684, https://clinicaltrials.gov/ct2/show/NCT03453684. Reprints will not be available from the authors. Address correspondence to Melissa Brooks Peterson, MD, Department of Anesthesiology, Section of Pediatric Anesthesiology, Children’s Hospital Colorado, University of Colorado School of Medicine, 13123 E 16th Ave, Box 090, Aurora, CO 80045. Address e-mail to melissa.brooks@childrenscolorado.org. © 2019 International Anesthesia Research Society

Risk of Hypoxemia by Induction Technique Among Infants and Neonates Undergoing Pyloromyotomy BACKGROUND: In patients presenting for pyloromyotomy, most practitioners prioritize rapid securement of the airway due to concern for aspiration. However, there is a lack of consensus and limited evidence on the choice between rapid sequence induction (RSI) and modified RSI (mRSI). METHODS: The medical records of all patients presenting for pyloromyotomy from May 2012 to December 2018 were reviewed. The risk of hypoxemia (peripheral oxygen saturation [SpO2], <90%) during induction was compared between RSI and mRSI cohorts for all patients identified as well as in the neonate subgroup by univariate and multivariable logistic regression analysis. Complications (aspiration, intensive care unit admission, bradycardia, postoperative stridor, and hypotension) and initial intubation success for both cohorts were also compared. RESULTS: A total of 296 patients were identified: 181 in the RSI and 115 in the mRSI cohorts. RSI was associated with significantly higher rates of hypoxemia than mRSI (RSI, 30% [23%–37%]; mRSI, 17% [10%–24%]; P = .016). In multivariable logistic regression analysis of all patients, the adjusted odds ratio (OR) of hypoxemia for RSI versus mRSI was 2.8 (95% confidence interval [CI], 1.5–5.3; P = .003) and the OR of hypoxemia for multiple versus a single intubation attempt was 11.4 (95% CI, 5.8–22.5; P < .001). In multivariable logistic regression analysis of neonatal subgroup, the OR of hypoxemia for RSI versus mRSI was 6.5 (95% CI, 2.0–22.2; P < .001) and the OR of hypoxemia for multiple intubation versus single intubation attempts was 18.1 (95% CI, 4.7–40; P < .001). There were no induction-related complications in either the RSI and mRSI cohorts, and the initial intubation success rate was identical for both cohorts (78%). CONCLUSIONS: In infants presenting for pyloromyotomy, anesthetic induction with mRSI compared with RSI was associated with significantly less hypoxemia without an observed increase in aspiration events. In addition, the need for multiple intubation attempts was a strong predictor of hypoxemia. The increased risk of hypoxemia associated with RSI and multiple intubation attempts was even more pronounced in neonatal patients. Accepted for publication June 17, 2019. Funding: None. Conflicts of Interest: See Disclosures at the end of the article. Reprints will not be available from the authors. Address correspondence to Raymond S. Park, MD, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, 300 Longwood Ave, Bader 3, Boston, MA 02115. Address e-mail to raymond.park@childrens.harvard.edu. © 2019 International Anesthesia Research Society

Monitoring of High- and Intermediate-Risk Surgical Patients No abstract available

Global and Regional Respiratory Mechanics During Robotic-Assisted Laparoscopic Surgery: A Randomized Study BACKGROUND: Pneumoperitoneum and nonphysiological positioning required for robotic surgery increase cardiopulmonary risk because of the use of larger airway pressures (Paws) to maintain tidal volume (VT). However, the quantitative partitioning of respiratory mechanics and transpulmonary pressure (PL) during robotic surgery is not well described. We tested the following hypothesis: (1) the components of driving pressure (transpulmonary and chest wall components) increase in a parallel fashion at robotic surgical stages (Trendelenburg and robot docking); and (2) deep, when compared to routine (moderate), neuromuscular blockade modifies those changes in PLs as well as in regional respiratory mechanics. METHODS: We studied 35 American Society of Anesthesiologists (ASA) I-II patients undergoing elective robotic surgery. Airway and esophageal balloon pressures and respiratory flows were measured to calculate respiratory mechanics. Regional lung aeration and ventilation was assessed with electrical impedance tomography and level of neuromuscular blockade with acceleromyography. During robotic surgical stages, 2 crossover randomized groups (conditions) of neuromuscular relaxation were studied: Moderate (1 twitch in the train-of-four stimulation) and Deep (1–2 twitches in the posttetanic count). RESULTS: Pneumoperitoneum was associated with increases in driving pressure, tidal changes in PL, and esophageal pressure (Pes). Steep Trendelenburg position during robot docking was associated with further worsening of the respiratory mechanics. The fraction of driving pressures that partitioned to the lungs decreased from baseline (63% ± 15%) to Trendelenburg position (49% ± 14%, P < .001), due to a larger increase in chest wall elastance (Ecw; 12.7 ± 7.6 cm H2O·L−1) than in lung elastance (EL; 4.3 ± 5.0 cm H2O·L−1, P < .001). Consequently, from baseline to Trendelenburg, the component of Paw affecting the chest wall increased by 6.6 ± 3.1 cm H2O, while PLs increased by only 3.4 ± 3.1 cm H2O (P < .001). PL and driving pressures were larger at surgery end than at baseline and were accompanied by dorsal aeration loss. Deep neuromuscular blockade did not change respiratory mechanics, regional aeration and ventilation, and hemodynamics. CONCLUSIONS: In robotic surgery with pneumoperitoneum, changes in ventilatory driving pressures during Trendelenburg and robot docking are distributed less to the lungs than to the chest wall as compared to routine mechanical ventilation for supine patients. This effect of robotic surgery derives from substantially larger increases in Ecw than ELs and reduces the risk of excessive PLs. Deep neuromuscular blockade does not meaningfully change global or regional lung mechanics. Accepted for publication April 4, 2019. Funding: This work was funded by Merck & Co. Conflicts of Interest: See Disclosures at the end of the article. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (www.anesthesia-analgesia.org). J. C. Brandão and M. A. Lessa contributed equally to this work and share first authorship. Clinical Trials Number: NCT02025075. URL: https://clinicaltrials.gov/ct2/show/NCT02025075. Reprints will not be available from the authors. Address correspondence to Marcos A. Lessa, MD, PhD, Laboratory of Cardiovascular Investigation, Oswaldo Cruz Institute, Fiocruz Foundation, Avenida Brasil 4365, Rio de Janeiro, Brazil 21045-900. Address e-mail to malessa@ioc.fiocruz.br. © 2019 International Anesthesia Research Society

Comparison of Macintosh Laryngoscopy in Bed-up-Head–Elevated Position With GlideScope Laryngoscopy: A Randomized, Controlled, Noninferiority Trial BACKGROUND: Approximately half of all difficult tracheal intubations (DTIs) are unanticipated; hence, proper positioning during intubation is critical to increase the likelihood of success. The bed-up-head–elevated (BUHE) intubation position has been shown to improve laryngeal view, reduce airway complications, and prolong safe apneic time during intubation. In this study, we sought to determine whether the BUHE intubation position is noninferior to Glidescope (GLSC)-assisted intubation with regard to laryngeal exposure. METHODS: A total of 138 American Society of Anesthesiologists (ASA) I to III patients were randomly assigned into 2 groups and underwent baseline laryngoscopy in the sniffing position. Group BUHE patients (n = 69) were then intubated in the BUHE position, while group GLSC patients (n = 69) were intubated using GLSC laryngoscopy. Laryngeal exposure was measured using Percentage of Glottic Opening (POGO) score and Cormack–Lehane (CL) grading, and noninferiority will be declared if the difference in mean POGO scores between both groups do not exceed −15% at the lower limit of a 98% confidence interval (CI). Secondary outcomes measured included time required for intubation (TRI), number of intubation attempts, use of airway adjuncts, effort during laryngoscopy, and complications during intubation. RESULTS: Mean POGO score in group BUHE was 80.14% ± 22.03%, while in group GLSC it was 86.45% ± 18.83%, with a mean difference of −6.3% (98% CI, −13.2% to 0.6%). In both groups, there was a significant improvement in mean POGO scores when compared to baseline laryngoscopy in the sniffing position (group BUHE, 25.8% ± 4.7%; group GLSC, 30.7% ± 6.8%) (P < .0001). The mean TRI was 36.23 ± 14.41 seconds in group BUHE, while group GLSC had a mean TRI of 44.33 ± 11.53 seconds (P < .0001). In patients with baseline CL 3 grading, there was no significant difference between mean POGO scores in both groups (group BUHE, 49.2% ± 19.6% versus group GLSC, 70.5% ± 29.7%; P = .054). CONCLUSIONS: In the general population, BUHE intubation position provides a noninferior laryngeal view to GLSC intubation. The laryngeal views obtained in both approaches were superior to the laryngeal view obtained in the sniffing position. In view of the many advantages of the BUHE position for intubation, the lack of proven adverse effects, the simplicity, and the cost-effectiveness, we propose that clinicians should consider the BUHE position as the standard intubation position for the general population. Accepted for publication June 24, 2019. Funding: This study was funded by the Malaysian Society of Anaesthesiologists K. Inbasegaran fund. The authors declare no conflicts of interest. Clinical trial registry: ClinicalTrials.gov (Registration identifier: NCT03357679). Reprints will not be available from the authors. Address correspondence to Samuel E. H. Tsan, MD, BMedSc, Department of Anaesthesiology, Faculty of Medicine and Health Sciences, University of Malaysia Sarawak, Jalan Datuk Mohammad Musa, 94300 Kota Samarahan, Sarawak, Malaysia. Address e-mail to tehsamuel@unimas.my. © 2019 International Anesthesia Research Society