Srikanth Sridhar

Anticipation of the difficult airway: preoperative airway assessment, an educational and quality improvement tool

BACKGROUND Assessment of the potentially difficult airway (DA) is a critical aspect of resident education. We investigated the impact of a new assessment form on airway prediction and management by anaesthesia residents. We hypothesized that residents would demonstrate improvement in evaluation of DAs over the study duration. METHODS After IRB approval, anaesthesia residents were randomized into two groups: control (existing form) and experimental (new form). Data were collected prospectively from August 2008 to May 2010 on all non-obstetric adult patients undergoing non-emergent surgery. RESULTS Eight thousand three hundred and sixty-four independent preoperative assessments were collected and 8075 were analysed. The experimental group had the higher completion rate than the control group (94.3% vs 84.3%, P=0.001). DA prediction was higher for the control group (71.2%) compared with the experimental group (69.1%; P=0.032). A significant improvement in prediction rates was found over time for the experimental group (likelihood estimate=0.00068, P=0.031). CONCLUSIONS The use of a comprehensive airway assessment did not improve resident ability to predict a DA in an academic, tertiary-based hospital, anaesthesiology residency training programme.

Resuscitative Endovascular Balloon Occlusion of the Aorta: Principles, Initial Clinical Experience, and Considerations for the Anesthesiologist

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an endovascular technique that allows for temporary occlusion of the aorta in patients with severe, life-threatening, trauma-induced noncompressible hemorrhage arising below the diaphragm. REBOA utilizes a transfemoral balloon catheter inserted in a retrograde fashion into the aorta to provide inflow control and support blood pressure until definitive hemostasis can be achieved. Initial retrospective and registry clinical data in the trauma surgical literature demonstrate improvement in systolic blood pressure with balloon inflation and improved survival compared to open aortic cross-clamping via resuscitative thoracotomy. However, there are no significant reports of anesthetic implications and perioperative management in this challenging cohort. In this narrative, we review the principles, technique, and logistics of REBOA deployment, as well as initial clinical outcome data from our level-1 American College of Surgeons–verified trauma center. For anesthesiologists who may not yet be familiar with REBOA, we make several suggestions and recommendations for intraoperative management based on extrapolation from these initial surgical-based reports, opinions from a team with increasing experience, and translated experience from emergency aortic vascular surgical procedures. Further prospective data will be necessary to conclusively guide anesthetic management, especially as potential complications and implications for global organ function, including cerebral and renal, are recognized and described.

Targeting Hypoxia Signaling for Perioperative Organ Injury

Perioperative organ injury has a significant impact on surgical outcomes and presents a leading cause of death in the United States. Recent research has pointed out an important role of hypoxia signaling in the protection from organ injury, including for example myocardial infarction, acute respiratory distress syndrome, acute kidney, or gut injury. Hypoxia induces the stabilization of hypoxia-inducible factors (HIFs), thereby leading to the induction of HIF target genes, which facilitates adaptive responses to low oxygen. In this review, we focus on current therapeutic strategies targeting hypoxia signaling in various organ injury models and emphasize potential clinical approaches to integrate these findings into the care of surgical patients. Conceptually, there are 2 options to target the HIF pathway for organ protection. First, drugs became recently available that promote the stabilization of HIFs, most prominently via inhibition of prolyl hydroxylase. These compounds are currently trialed in patients, for example, for anemia treatment or prevention of ischemia and reperfusion injury. Second, HIF target genes (such as adenosine receptors) could be activated directly. We hope that some of these approaches may lead to novel pharmacologic strategies to prevent or treat organ injury in surgical patients.

Dramatic change in cerebral oximetry during liver transplantation

ABSTRACT We report dramatic changes in bilateral cerebral tissue oxygenation in a patient undergoing an orthotopic liver transplant coincident with clamping and subsequent restoration of flow through the inferior vena cava. Although hemodynamic stability was maintained with low-dose vasopressor support, cardiac output was decreased, suggesting preload dependence of the measured cerebral oxygenation. Further investigation is warranted in patients with end-stage liver disease and interruption of venous return.

Reliability of a faculty evaluated scoring system for anesthesiology resident applicants (Original Investigation)

STUDY OBJECTIVE To assess reliability and reproducibility of a recently instituted anesthesiology resident applicant interview scoring system at our own institution. DESIGN Retrospective evaluation of 2 years of interview data with a newly implemented scoring system using randomly assigned interviewing faculty. SETTING Interview scoring evaluations were completed as standard practice in a large academic anesthesiology department. SUBJECTS All anesthesiology resident applicants interviewed over the 2013/14 and 2014/15 seasons by a stable cohort of faculty interviewers. Data collection blinded for both interviewers and interviewees. INTERVENTIONS None for purposes of study - collation of blinded data already used as standard practice during interview process and analysis. MEASUREMENTS None specific to study. MAIN RESULTS Good inter-rater faculty reliability of interview scoring (day-of) and excellent inter-faculty reliability of application review (pre-interview). CONCLUSIONS Development of a department-specific interview scoring system including many elements beyond traditional standardized tests shows good-excellent reliability of faculty scoring of both the interview itself (including non-technical skills) and the application resume.

All Work Hours Are Not Equal

To the Editor: We read Baird et al.’s1 recent description of gender differences and trends in the anesthesiology workforce with great interest. As members of a large, vibrant academic level 1 trauma center with busy transplant and neurosurgical services, we observe that several issues raised by the 2013 RAND survey are relevant. We are a particularly diverse faculty group with a greater proportion of female anesthesiologists (49%) than represented in the study (26%). At first glance, the conclusion that female anesthesiologists receive lower total and hourly compensation irrespective of the fewer hours worked is alarming. However, the context for this is the significantly three-fold greater part-time (defined as less than 35 h/week) employees in the female group, which in itself may explain the apparent discrepancy as 11% of that gender cohort. In a busy facility such as ours with increasing hospital demand for expansion of services, an employee working part-time in a 7 Am to 3 or 5 pm shift adds value to meeting the elective needs of the operating room. However, a significant proportion of urgent and emergency service is provided after hours, on weekends, and on public holidays, and it is both plausible and logical for the larger full-time (by definition, larger male) cohort taking these calls to receive greater compensation. If, as the authors suggest, marital status and the presence of children affect gender hours, then on-call overnight and weekend hours must be valued more significantly than routine office hours. With reasonable call shifts (14 h on weekdays and 12 h on weekends) and generous use of postcall days, it is not surprising that a faculty member taking calls, irrespective of gender, may not have significantly total increased hours compared to a weekday-only anesthesiologist. However, with increasing hospital demands, the flexibility of on-call faculty members to take additional preand/or postcall shifts is increasingly valuable and facilitates management of the daily schedule. Given the increasing proportion of female anesthesiologists in almost all age groups documented in the article, there will also be an increasing proportion of part-time anesthesiologists, which may negatively impact both the on-call cohort and flexibility in schedule management. For these population. The intuition of Dr. pivalizza et al. regarding the conduct of reasonable clinicians is therefore unsupported. Carette et al. raise the important point that using non–age-adjusted mAC values might have affected our conclusions. They could be right in that “single high” (age) might be much more important than “triple low” and that some of the patients in our study included in the “triple low” group might only have had “double low” (low mean arterial pressure and low bispectral index) when considering age-adjusted mAC. We chose the methodology in our study to approximate the approach that was used by Sessler et al.,5 who chose not to use ageadjusted mAC values. But our findings would not have changed substantially had we used age-adjusted mAC. Based on the population in our study, the low mAC cutoff would likely have shifted from the (arbitrary) 0.8 age-unadjusted value to about 0.9 age-adjusted mAC.6,7 Furthermore, although age was associated with 30and 90-day mortality in the multivariable analyses, “triple low” remained independently linked to death despite the inclusion of age as a variable in the models. It is also notable that age was one of the variables used in our propensity score matching. In conclusion, we apologize if the letter writers or readers were alarmed by our study or our conclusions. We wish to clarify that we do not believe that our findings mandate any changes in clinical practice, and we remain skeptical that “triple low” is causally implicated in postoperative death.

Is the “triple Low” Association with Death Statistically Valid or Reflective of Clinical Practice?

To the Editor: We are intrigued to read Willingham et al.’s1 strongly worded retrospective, observational conclusion from three previously reported trials that the concurrence of intraoperative hypotension, low minimum alveolar concentration, and low bispectral index (BIS), the so-called “triple low,” was independently associated with postoperative death. We have several observations noting that several of the current authors were original contributors to the referenced studies.

Dangerous Regulations for a Level 1 Trauma Operating Room.

1. Their estimated 5to 10-minute arterial line monitoring system setup time presumes immediate availability of a dedicated technician or anesthesiologist. At our busy facility, especially in after-hours scenarios, this may be longer. Recent data from Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) highlighted the first 3 hours of traumarelated mortality,2 and delaying arterial line access for a fraction of these golden hours has the ability to cause patient harm. 2. Direct admissions from the helipad or emergency room frequently occur in <5 minutes and would preclude safe preparation of monitoring systems or necessary medications at that time. 3. As with many academic centers, clinical responsibility is coupled with educational requirements, including a new intake of one-third of the effective resident and one-half of the Anesthesiologist Assistant student cohort every summer, coinciding with the busiest period of the trauma season. With new personnel, it is imperative that arterial line monitoring systems, induction, and rescue medications are prepared and immediately available to avoid delay in care. 4. We agree with the plea for evidence-based recommendations. In our collective experience, we have not seen an infection at an arterial line site that was placed urgently or emergently in the operating room. If there is concern for sterility or infection, the arterial line can be safely replaced once the patient is not in extremis.

Anticipation of the Difficult Airway: Preoperative Airway Assessment, an Educational and Quality Improvement Tool

Careful airway assessment before anesthesia induction and perioperative airway management are critical responsibilities of the anesthetist. However, despite improvements in patient monitoring, airway devices, clinical protocols, and training, which have reduced the risk associated with an unpredicted difficult airway (DA), these changes have not reduced the incidence of unanticipated DAs in clinical practice. This prospective, randomized, single-blind study was undertaken to investigate the impact of a new assessment form on airway prediction and management by anesthesia residents, based on the hypothesis that residents would improve in their evaluation of DAs during the study. Adult nonobstetric patients undergoing elective surgery requiring general anesthesia were enrolled in the study if their airway was not already secured. Ninety-one residents were randomized to use the new comprehensive airway assessment form along with the existing form or the existing anesthesia preoperative assessment form only. The new form required a detailed assessment of the patient’s airway history and physical examination. Difficult mask ventilation was defined as difficulty in maintaining a mask seal and obtaining satisfactory capnography (end-tidal CO2 and tidal volume). Difficult supraglottic airway was defined as either inability to physically place a supraglottic device or inadequacy of ventilation, oxygenation, or airway protection after placement that required conversion to another technique. Difficult direct laryngoscopy was defined as difficulty in visualizing any portion of the vocal cords after conventional laryngoscopy requiring more than 1 attempt. Difficult intubation was defined as proper insertion of the tracheal tube with conventional laryngoscopy requiring multiple attempts. Difficult surgical airway was considered as a difficult cricothyrotomy or tracheostomy, open or percutaneous, performed electively or emergently, to manage a DA due to bleeding, poor orientation, and difficult instrumentation. The database included 9117 postoperative encounters, but the 155 patients who received multiple anesthetics were excluded from the analysis. All statistical analyses were performed using SAS 9.2 (SAS Institute, Cary, NC). P < 0.05 indicated statistical significance. Of the 83,645 preoperative assessments, 8075 assessments were included in the final analysis, with 3332 (41%) performed by the experimental group and 4743 performed by the control

Airway Management in Cervical Spine Injured Patients

Cervical spine injury (CSI) creates a special problem in airway management. The cervical spine is comprised of seven vertebrae that are uniquely configured and house the spinal cord at the center. The configuration of the cervical spine allows specific movements of the head and neck in a limited fashion. Cervical instability is a serious concern and occurs when movement in the spine is greater than normal, possibly placing the spinal cord at risk. Spinal cord injury is the primary concern when considering CSI, and can occur in a number of scenarios and pathologies, the most worrisome of which are direct injury and spinal cord compression. Evaluation and initial management of CSI should include radiographic assessment in patients at particular risk, early cervical immobilization, and potentially elective intubation. Recognition of CSI in association with other traumatic injuries is critical. When approaching the airway of a CSI patient, recognition of injury and timely intubation are critical. Direct laryngoscopy with manual in-line stabilization (MILS) is the most commonly practiced technique and is considered safe; other options for intubation include flexible fiberoptic intubation, video laryngoscopy, laryngeal mask airway (LMA) use, and nasal intubation. Regardless of the modality used, airway management must be conducted with regard for securing the airway as quickly and safely as possible while maintaining cervical immobilization.