A Prospective Cohort Study on the Respiratory Effect on Modified Mallampati Scoring.

Background: Mallampati scoring is a common exam method for evaluating the oropharynx as a part of the airway assessment and for anticipation of difficult intubation. It partitions the oropharynx into 4 categories with scores of 1, 2, 3, and 4. Even though its reliability is known to be limited by confounding factors such as patient positioning, patient phonation, tongue protrusion, and examiner variability, the effect of respiration, i.e., inspiration and expiration, has not yet been formally studied. Methods: Mallampati scores were collected from 100 surgical patients during both inspiration and expiration and later compared to the score obtained in the medical record, determined by a board certified anesthesiologist. Results: Score deviations from the medical record reference were compared for both inspiration and expiration showing that respiration affects Mallampati scores; for some patients, the scores improved (i.e., decreased), while in others they worsened (i.e., increased). The respiratory change effect was quantified and visualized by plotting the area under the curve of the histogram of the deviations. 42% of the patients had a worsening of scores by 1 or 2 points with inspiration while 36% of the patients had a worsening of scores by 1 or 2 points with expiration. Conclusions: Mallampati scoring is commonly used in evaluating the oropharynx as a part of the airway assessment and as a screening tool for difficult intubations. However, as this study points out, the respiratory cycle substantially affects the Mallampati scoring system, with significant deviations of 1 or 2 points. In a scoring system of 4 score categories, these deviations are remarkable.

Near-miss hypoglycemia-reflections on perioperative glucose management guidelines in diabetics.

BACKGROUND: The American Society of Anesthesiologists (ASA) has an impressive array of professional perioperative guidelines but has not issued a guideline specific to perioperative blood glucose management and does not delve into the topic in their other guidelines. CASE REPORT: We experienced a perioperative case that highlights the potential difficulty of glucose management in this setting. During anesthetic induction for an orthopedic foot surgery, as the medication was infusing, an IDDM 1 (insulin dependent diabetes mellitus type 1) patient expressed feeling that her blood sugar level was low. Her finger stick after induction showed severe hypoglycemia with a blood glucose of 34 mg/dL. The hypoglycemia was treated with intravenous glucose and further closely monitored. CONCLUSIONS: This case led us to revisit the different perioperative guidelines and recommendations for diabetic patients and this manuscript aims to highlight the similarities and discrepancies among the different published recommendations. This case highlights the value of utilizing insulin pump infusions in the perioperative setting when available.

A Survey-Based Assessment of the Practices Governing Morbidity and Mortality Conferences and the Effects of the COVID-19 Pandemic.

Background: Morbidity and mortality (M&M) conferences are essential components for resident education and provide a valuable tool to improve patient safety and quality of care. M&M conferences help identify important gaps in safety and reduce avoidable events in future patient care. Active methods to improve the utilization of M&M conferences have been shown to enhance their educational value for residents, faculty and multidisciplinary teams in healthcare institutions. Objective: The purpose of this study was to use a survey-based methodology to assess how morbidity and mortality conferences are conducted in residency programs, including characteristics such as frequency, involvement of personnel and the effects of COVID-19. Methods: From February to October 2021, a validated 19 question survey was electronically distributed to residency program directors in anesthesiology, emergency medicine and general surgery, after a search for email addresses in the ACGME database. The survey was created and hosted on Google Forms. Results: A total of 125 of 713 program directors (17.5%) responded to the survey. Eighty-three percent of respondent programs reported mandatory participation for residents, with residents providing most of the presentations. Case presentations utilized various formats including SBAR, adverse event analysis and root cause analysis as the most common modalities. Though most programs reported no change in frequency of M&M conferences due to COVID-19, most respondents reported a shift to a virtual or hybrid platform. Conclusion: M&M conferences are an important educational and quality improvement modality, and many residency directors changed practice to incorporate virtual platforms due to the COVID-19 pandemic to maintain uninterrupted educational sessions. Nonetheless, significant variation still exists in how these conferences are conducted between different institutions.

Human life cost in anaesthesiology cost-benefit decisions.

The United States (US) aviation industry provides a potentially useful mental model for dealing with certain cost-benefit decisions in aesthesiology. The Federal Aviation Administration (FAA), the national aviation authority of the United States, quantifies a price for the value of a human life based on the U.S. Department of Transportation's (DOT) value of a statistical life (VSL) unit. The current VSL is around $9.6 million, indexed to grow with consideration given to inflation and wage changes from the 2016 baseline of $9.4 million [1]. To illustrate the concept, if the FAA estimates that 100 people are likely to die in the future given the current practice standards then the monetary cost of this loss will be $940 million. The FAA uses this estimated monetary value as an official reference point in its regulatory decisions, and the agency publishes in detail how it derives the estimated value. When proposing new regulations, the FAA bases its decisions on comparisons of the human life cost associated with the existing regulation versus the alternative cost that the industry stakeholders will incur subsequent to the adoption of the regulation. In this example, if the cost incurred by the industry is more than the $940 million cost then the FAA will not adopt the proposed regulation and hence will not require the industry to undertake this cost.

Application of a conversion factor to estimate the adenoma detection rate from the polyp detection rate.

BACKGROUND: The adenoma detection rate (ADR) is a quality benchmark for colonoscopy. Many practices find it difficult to determine the ADR because it requires a combination of endoscopic and histologic findings. It may be possible to apply a conversion factor to estimate the ADR from the polyp detection rate (PDR). OBJECTIVE: To create a conversion factor that can be used to accurately estimate the ADR from the PDR. DESIGN: This was a retrospective study of colonoscopies performed by board-certified gastroenterologists to determine the average adenoma to polyp detection rate quotient (APDRQ) for all endoscopists, individually and as a group. SETTING: Academic group practice. INTERVENTION: The group average APDRQ was used as a conversion factor for the endoscopist's PDR to estimate the ADR. MAIN OUTCOME MEASUREMENTS: The strength of the relationship between the estimated ADR and the actual ADR determined by Pearson's correlation coefficient. RESULTS: A total of 3367 colonoscopies performed by 20 staff gastroenterologists were included. The average ADR for all indications, all patient age groups, and both sexes was 0.17 (range 0.09-0.27, standard deviation 0.05). The average APDRQ was 0.64 (range 0.46-1.00, standard deviation 0.13). The correlation between the estimated ADR and the actual ADR was 0.85 (95% CI, 0.65-0.93, P = .000001). LIMITATIONS: Retrospective study in 1 practice setting with all patient types. CONCLUSIONS: The use of a conversion factor can accurately estimate the ADR from the PDR. Further study is needed to determine whether such a conversion factor can be applied to different practice settings and patient groups.

Kinetic and thermodynamic studies of peptidyltransferase in ribosomes from the extreme thermophile Thermus thermophilus.

Throughout evolution, emerging organisms survived by adapting existing biochemical processes to new reaction conditions. Simple protein enzymes balanced changes in structural stability with changes that permitted optimal catalysis by adjustments in both entropic and enthalpic contributions to the free energy of activation for the reaction. Study of adaptive mechanisms by large multicomponent enzymes such as the ribosome has been largely unexplored. Here we have determined the kinetic and thermodynamic parameters of peptidyltransferase in ribosomes from the extreme thermophile Thermus thermophilus. Activity of thermophilic enzymes can be assayed over a wide range of temperatures, enabling one to measure accurate catalytic rates and determine enthalpic and entropic contributions to the free energy of activation of the reaction. Differences in the reaction conditions used here and in published studies on mesophilic ribosomes prevent direct comparison, but our data on Thermus ribosomes suggest that these ribosomes have adapted to changing environments using the same strategies as simple protein enzymes, balancing stability and flexibility without loss of catalytic rate. This strategy must be a very ancient process, perhaps first used by primitive ribosomes in the RNA World.

Mutational analysis of 16S and 23S rRNA genes of Thermus thermophilus.

Structural studies of the ribosome have benefited greatly from the use of organisms adapted to extreme environments. However, little is known about the mechanisms by which ribosomes or other ribonucleoprotein complexes have adapted to functioning under extreme conditions, and it is unclear to what degree mutant phenotypes of extremophiles will resemble those of their counterparts adapted to more moderate environments. It is conceivable that phenotypes of mutations affecting thermophilic ribosomes, for instance, will be influenced by structural adaptations specific to a thermophilic existence. This consideration is particularly important when using crystal structures of thermophilic ribosomes to interpret genetic results from nonextremophilic species. To address this issue, we have conducted a survey of spontaneously arising antibiotic-resistant mutants of the extremely thermophilic bacterium Thermus thermophilus, a species which has featured prominently in ribosome structural studies. We have accumulated over 20 single-base substitutions in T. thermophilus 16S and 23S rRNA, in the decoding site and in the peptidyltransferase active site of the ribosome. These mutations produce phenotypes that are largely identical to those of corresponding mutants of mesophilic organisms encompassing a broad phylogenetic range, suggesting that T. thermophilus may be an ideal model system for the study of ribosome structure and function.

Genetic evidence against the 16S ribosomal RNA helix 27 conformational switch model.

A mechanistic understanding of ribosome function demands knowledge of the conformational changes that occur during protein synthesis. One current model proposes a conformational switch in Helix 27 (H27) of 16S rRNA involved in the decoding of mRNA. This model was based on the behavior of mutations in the 912 region of H27 of Escherichia coli 16S rRNA, which were predicted to stabilize the helix in either of two alternative conformations. This interpretation was supported by evidence from both genetics and structural biochemistry. However, recently published X-ray crystallographic structures of the Thermus thermophilus 30S subunit at different stages of tRNA selection have raised doubts regarding the validity of this model. We have therefore revisited the model genetically by constructing a H27 quadruple mutation (C912G, C910G, G885C, and G887C), which would create multiple mismatches in the proposed alternative conformation without perturbing the native H27 conformation seen in the crystal structures. Inconsistent with the H27 switch model, cells containing pure populations of quadruple mutant ribosomes grow at essentially wild-type rates. The mutants used to construct the H27 switch model all carried A2058G in 23S rRNA and C1192U in 16S rRNA as selectable markers. The quadruple mutant carrying these additional marker mutations is deleterious, and we conclude that they have a synergistic effect when combined with other mutations and are not phenotypically silent. Their presence confounded the interpretation of the original mutant phenotypes and, in light of the viability of the quadruple mutant, we conclude that the genetic evidence no longer supports the model.