Neurobehavioral Abnormalities in Offspring of Young Adult Male Rats With a History of Traumatic Brain Injury

Children of parents with traumatic brain injury (TBI) are more likely to develop psychiatric disorders. This association is usually attributed to TBI-induced changes in parents' personality and families' social environment. We tested the hypothesis that offspring of young adult male rats with TBI develop neurodevelopmental abnormalities in the absence of direct social contact with sires. Male Sprague-Dawley rats (F0 generation) in the TBI group underwent moderate TBI via a midline fluid percussion injury that involved craniectomy under sevoflurane (SEVO) anesthesia for 40 min on post-natal Day 60 (P60), while F0 rats in the control group were placed in a new cage, one per cage, for the equivalent time duration. A subset of F0 rats was sacrificed on P66 to assess acute changes in hypothalamic-pituitary-adrenal (HPA) axis and inflammation markers. The remaining F0 males were mated with naive females on P90 to generate offspring (F1 generation). The F0 males and F1 males and females were sequentially evaluated in the elevated plus maze, for pre-pulse inhibition of acoustic startle, in the Morris water maze, and for resting and stress levels of serum corticosterone starting on ∼P105 (F0) and ∼P60 (F1), followed by tissue collection for further analyses. Acutely, the F0 TBI males had messenger RNA (mRNA) transcripts altered to support an increased hypothalamic and hippocampal Na+-K+-Cl- (Slc12a2) Cl- importer / K+-2Cl- (Slc12a5) Cl- exporter ratio and decreased hippocampal glucocorticoid receptors (Nr3c1), as well as increased serum levels of corticosterone, interleukin-1β (IL-1β), and biomarkers of activated hippocampal microglia and astrocytes. Long-term, F0 TBI rats exhibited increased corticosterone concentrations at rest and under stress, anxiety-like behavior, impaired sensory-motor gating, and impaired spatial memory. These abnormalities were underpinned by reduced mRNA levels of hypothalamic and hippocampal mineralocorticoid receptors (Nr3c2), hippocampal Nr3c1, and hypothalamic brain-derived neurotrophic factor (Bdnf), as well as elevated serum levels of IL-1β, and biomarkers of activated hippocampal microglia and astrocytes. F1 male offspring of TBI sires exhibited abnormalities in all behavioral tests, while their F1 female counterparts had abnormal pre-pulse inhibition responses only. F1 male offspring of TBI sires also had reduced mRNA levels of hippocampal Nr3c1 and Nr3c2, as well as hypothalamic and hippocampal Bdnf, whereas increases in inflammatory markers were more profound in F1 females. These findings suggest that offspring of sires with a history of a moderate TBI that involved craniectomy under SEVO anesthesia for 40 min, develop sex-dependent neurobehavioral abnormalities in the absence of direct social interaction between the sire and the offspring.

A Single-Center Retrospective Review of Patients with Suspected Malignant Hyperthermia Susceptibility

Purpose The diagnosis of malignant hyperthermia susceptibility (MHS) has significant implications for the perioperative period that may persist for generations. Anesthetic medication options are reduced, anesthetic workstations require preparation to reduce exposure to inhaled volatile anesthetics, and patients may be excluded from surgery at ambulatory centers. In this study, we sought to better characterize the etiology of MHS diagnoses in our health system and the downstream effects of this diagnosis on anesthetic care. Methods We retrospectively reviewed the electronic medical records of 55 patients with a documented concern for MHS who received care at University of Florida (UF) Health between 2014 and 2020. We characterized the etiology of the patient's MHS diagnosis, whether this diagnosis was supported by formal genetic or muscle contracture testing, and the details of the recorded anesthetics that were delivered to these patients. Results The 55 patients with suspected MHS were evenly split between those with a family history of malignant hyperthermia (MH) (28/55) and those with a concern for MHS in their personal medical history (27/55). Of the 28 patients with a family history of MH, 16 reported that the affected family member was a first-degree relative, and two of these 16 reported that the affected family member had undergone confirmatory muscle contracture testing. Of the 27 patients with a personal history suspicious for MHS, two had undergone confirmatory genetic testing, and two patients had anesthetic records available for review where intraoperative MH was suspected and treated with dantrolene. An additional four patients were told of a concern about MHS due to another underlying diagnosis. No patients with a personal history suspicious of MHS had undergone confirmatory muscle contracture testing. These 55 patients underwent 87 anesthetics, and exclusively non-triggering anesthetic techniques were utilized in nearly all cases. In pediatric patients, some perioperative challenges were identified, related to the avoidance of mask inhalational induction. Only six of these 87 anesthetics occurred at our ambulatory surgery centers, a proportion (6.9%) lower than that of the general surgical population at UF Health (20.0%). Conclusions Among patients suspected to be MH susceptible in our health system over a six-year period, a minority (8/55) were supported by clear records of a prior MH event, confirmatory genetic or muscle contracture testing, or an underlying diagnosis closely linked to MH. The vast majority had limited documentation supporting their MH risk but continued to be treated with non-triggering anesthetics and were less likely to have surgery at an ambulatory surgery center than our overall surgical population. Among pediatric patients, some anesthetic challenges related to delivering non-triggering anesthetics were identified. Improving the documentation of index cases of MH and increasing referrals to clinical geneticists and genetic testing may be a viable route to decreasing the proportion of suspected MHS patients with a poorly characterized risk profile.

The Effect of Computer Tablets on the Need for Medical Anxiolysis in Children in an Ambulatory Surgical Center

Background Preoperative anxiety is common in children undergoing surgery. When anxiety is identified or suspected, there are several strategies typically used to manage it. Perhaps the most common is anxiolytic premedication or parental presence at induction. Medications such as midazolam have been associated with adverse effects, such as a slower wakeup, and require timing of administration, while parental presence can be disturbing to the parent and divert the attention of the operating room team. A more recent option is distraction via electronic tablets. The purpose of this study was to retrospectively investigate and quantify any change in the use of midazolam, the most common anxiolytic approach at our institution, and any change in the length of time in the post-anesthesia care unit (PACU) following the introduction of tablet computers to a pediatric ambulatory surgical center. Methods We conducted an IRB-approved retrospective chart review of 13,790 pediatric patients ages one to 18 undergoing outpatient elective surgeries at the University of Florida (UF) Children's Surgical Center over a five-year period. A univariate analysis was conducted using the Fisher's Exact test and interrupted time series analysis to determine differences between midazolam administration and PACU times, with interruption occurring at tablet implementation. A multivariable analysis and sensitivity analyses were performed to confirm the findings of the univariate analysis. Results On univariate analysis, tablet availability was associated with both a decreased preoperative oral midazolam administration (odds ratio (OR) 0.158, 95% confidence interval (CI): 0.140 to 0.179, P-value <0.001) and a decreased PACU length of stay (-17.4 min, 95% CI: -19.6 to -15.3 min, P-value <0.001). The association with decreased preoperative midazolam administration held after multivariable analysis (adjusted OR 0.207, 95% CI: 0.154 to 0.278, P-value <0.001), but PACU length of stay was not statistically significant (-9.1 min, 95% CI: -20.6 to 2.4, P-value = 0.12). These results were confirmed on sensitivity analysis, with tablet availability continuing to be associated with decreased preoperative oral midazolam administration but not with reduced PACU length of stay. Conclusion Our results demonstrate that computer tablets were associated with a significant decrease in the frequency of midazolam administration and consequently may reduce preoperative pediatric anxiety. We did not find an associated change in PACU length of stay following the introduction of tablets. Tablets present a unique distraction alternative to chemical anxiolysis for institutions seeking to reduce medication use in pediatric patients.

Intergenerational Perioperative Neurocognitive Disorder in Young Adult Male Rats with Traumatic Brain Injury

BACKGROUND

The authors tested the hypothesis that the effects of traumatic brain injury, surgery, and sevoflurane interact to induce neurobehavioral abnormalities in adult male rats and in their offspring (an animal model of intergenerational perioperative neurocognitive disorder).

METHODS

Sprague-Dawley male rats (assigned generation F0) underwent a traumatic brain injury on postnatal day 60 that involved craniectomy (surgery) under 3% sevoflurane for 40 min followed by 2.1% sevoflurane for 3 h on postnatal days 62, 64, and 66 (injury group). The surgery group had craniectomy without traumatic brain injury, whereas the sevoflurane group had sevoflurane only. On postnatal day 90, F0 males and control females were mated to generate offspring (assigned generation F1).

RESULTS

Acutely, F0 injury rats exhibited the greatest increases in serum corticosterone and interleukin-1β and -6, and activation of the hippocampal microglia. Long-term, compared to controls, F0 injury rats had the most exacerbated corticosterone levels at rest (mean ± SD, 2.21 ± 0.64 vs. 7.28 ± 1.95 ng/ml, n = 7 - 8; P < 0.001) and 10 min after restraint (133.12 ± 33.98 vs. 232.83 ± 40.71 ng/ml, n = 7 - 8; P < 0.001), increased interleukin-1β and -6, and reduced expression of hippocampal glucocorticoid receptor (Nr3c1; 0.53 ± 0.08 fold change relative to control, P < 0.001, n = 6) and brain-derived neurotrophic factor genes. They also exhibited greater behavioral deficiencies. Similar abnormalities were evident in their male offspring, whereas F1 females were not affected. The reduced Nr3c1 expression in F1 male, but not female, hippocampus was accompanied by corresponding Nr3c1 promoter hypermethylated CpG sites in F0 spermatozoa and F1 male, but not female, hippocampus.

CONCLUSIONS

These findings in rats suggest that young adult males with traumatic brain injury are at an increased risk of developing perioperative neurocognitive disorder, as are their unexposed male but not female offspring.

EDITOR’S PERSPECTIVE

Optimizing Pediatric Mask Induction Fresh Gas Flow

INTRODUCTION

The environmental impact of inhaled anesthetics is a subject of increasing research. However, little attention has been paid to optimizing high-concentration volatile anesthetics during the inhalational (mask) inductions that begin most pediatric anesthetics.

METHODS

The performance of the GE Datex Ohmeda TEC 7 sevoflurane vaporizer was analyzed at different fresh gas flow (FGF) rates and two clinically relevant ambient temperatures. We found that an FGF rate of 5 liters per minute (LPM) is likely optimal for inhalational inductions, rapidly achieving dialed sevoflurane concentrations at the elbow of an unprimed pediatric breathing circuit while minimizing waste associated with higher FGF rates. We began educating our department regarding these findings, first with QR code labels on anesthetic workstations, then with targeted e-mails to pediatric anesthesia teams. We analyzed peak induction FGF in 100 consecutive mask inductions at our ambulatory surgery center at three different periods - baseline, post-labels, and post-emails - to assess the efficacy of these educational interventions. We also analyzed the time from induction to the start of myringotomy tube placement in a subset of these cases to determine if reducing mask induction FGF was associated with any change in the speed of induction.

RESULTS

Our institution's median peak FGF during inhalational inductions decreased from 9.2 LPM at baseline to 8.0 LPM after labels were placed on anesthetic workstations to 4.9 LPM after targeted e-mails. There was no associated decrease in the speed of induction.

CONCLUSION

Total fresh gas flow can be limited to 5 LPM during pediatric inhalational inductions, decreasing anesthetic waste and environmental impact without slowing the speed of induction. Educational labels on anesthetic workstations and direct e-mails to clinicians were effectively used in our department to enact change in this practice.

Dexmedetomidine Diminishes, but Does Not Prevent, Developmental Effects of Sevoflurane in Neonatal Rats

BACKGROUND

Sevoflurane (SEVO) increases neuronal excitation in neonatal rodent brains through alteration of gamma aminobutyric acid (GABA)(A) receptor signaling and increases corticosterone release. These actions may contribute to mechanisms that initiate the anesthetic's long-term neuroendocrine and neurobehavioral effects. Dexmedetomidine (DEX), a non-GABAergic α2-adrenergic receptor agonist, is likely to counteract SEVO-induced neuronal excitation. We investigated how DEX pretreatment may alter the neurodevelopmental effects induced by SEVO in neonatal rats.

METHODS

Postnatal day (P) 5 Sprague-Dawley male rats received DEX (25 µg/kg, intraperitoneal) or vehicle before exposure to 2.1% SEVO for 6 hours (the DEX + SEVO and SEVO groups, respectively). Rats in the DEX-only group received DEX without exposure to SEVO. A subcohort of P5 rats was used for electroencephalographic and serum corticosterone measurements. The remaining rats were sequentially evaluated in the elevated plus maze on P80, prepulse inhibition of the acoustic startle response on P90, Morris water maze (MWM) starting on P100, and for corticosterone responses to physical restraint for 30 minutes on P120, followed by assessment of epigenomic DNA methylation patterns in the hippocampus.

RESULTS

Acutely, DEX depressed SEVO-induced electroencephalogram-detectable seizure-like activity (mean ± SEM, SEVO versus DEX + SEVO, 33.1 ± 5.3 vs 3.9 ± 5.3 seconds, P < .001), but it exacerbated corticosterone release (SEVO versus DEX + SEVO, 169.935 ± 20.995 versus 280.853 ± 40.963 ng/mL, P = .043). DEX diminished, but did not fully abolish, SEVO-induced corticosterone responses to restraint (control: 11625.230 ± 877.513, SEVO: 19363.555 ± 751.325, DEX + SEVO: 15012.216 ± 901.706, DEX-only: 12497.051 ± 999.816; F[3,31] = 16.878, P < .001) and behavioral deficiencies (time spent in the target quadrant of the MWM: control: 31.283% ± 1.722%, SEVO: 21.888% ± 2.187%, DEX + SEVO: 28.617% ± 1.501%, DEX-only: 31.339% ± 3.087%; F[3,67] = 3.944, P = .012) in adulthood. Of the 391 differentially methylated genes in the SEVO group, 303 genes in the DEX + SEVO group had DNA methylation patterns that were not different from those in the control group (ie, they were normal). DEX alone did not cause acute or long-term functional abnormalities.

CONCLUSIONS

This study suggests that the ability of DEX to depress SEVO-induced neuronal excitation, despite increasing corticosterone release, is sufficient to weaken mechanisms leading to long-term neuroendocrine/neurobehavioral abnormalities. DEX may prevent changes in DNA methylation in the majority of genes affected by SEVO, epigenetic modifications that could predict abnormalities in a wide range of functions.

Impact of Simulation on Critical Care Fellows’ Electroencephalography Learning

Introduction

Continuous electroencephalography (EEG) is an important monitoring modality in the intensive care unit and a key skill for critical care fellows (CCFs) to learn. Our objective was to evaluate with CCFs an EEG educational curriculum on a web-based simulator.

Methods

This prospective cohort study was conducted at a major academic medical center in Florida. After Institutional Review Board approval, 13 CCFs from anesthesiology, surgery, and pulmonary medicine consented to take an EEG curriculum. A 25-item EEG assessment was completed at baseline, after 10 EEG interpretations with a neurophysiologist, and after 10 clinically relevant EEG-based simulations providing clinical EEG interpretation hints. A 50-minute tutorial podcast was viewed after the baseline assessment. Main assessment outcomes included multiple outcomes related to web-based simulator performance: percent of hints used, percent of first words on EEG interpretation correct, and percent hint-based EEG interpretation score correct, with higher scores indicating more correct answers. Participants completed a 25-item EEG assessment before (baseline) and after the web-based simulator.

Results

All 13 CCFs completed the curriculum. Between scenarios, there were differences in percent of hints used (F_9,108 = 11.7, p < 0.001), percent of first words correct (F_9,108 = 13.6, p < 0.001), and overall percent hint-based score (F_9,108 = 14.0, p < 0.001). Nonconvulsive status epilepticus had the lowest percent of hints used (15%) and the highest hint-based score (87%). Overall percent hint-based score (mean across all scenarios) was positively correlated with change in performance as the number of correct answers on the 25-item EEG assessment from before to after the web-based simulator activity (Spearman’s rho = 0.67, p = 0.023).

Conclusions

A self-paced EEG interpretation curriculum involving a flipped classroom and screen-based simulation each requiring less than an hour to complete significantly improved CCF scores on the EEG assessment compared to baseline.

Manual Conservation of Supplemental Oxygen in Low-Resource Settings During the COVID-19 Pandemic

SUMMARY STATEMENT

Using a simulated adult COVID-19 patient with hypoxemia, we investigated whether caregivers interrupting oxygen flow by manually occluding oxygen tubing with pliers during exhalation can conserve oxygen while maintaining oxygenation. Oxygen pinching reduced oxygen use by 51% to 64%, maintained simulated oxygen saturation between 88% and 90%, and increased simulated average alveolar partial pressure of oxygen from a room air baseline of approximately 131 to 294-424 mm Hg compared with 607 mm Hg with 10 liters per minute (LPM) continuous oxygen flow. Simulation provided a methodology to rapidly evaluate a technique that has begun to be used with COVID-19 patients in low-resource environments experiencing an acute oxygen shortage.

Carbon Dioxide Elimination After Sodium Bicarbonate Administration as a Novel Method to Assess Cardiac Output: A Pilot Study

Introduction

Cardiac output/pulmonary blood flow measurement is an important way to assess patients during the perioperative period, as well as patients who are critically ill. Current methods of assessing cardiac output have limitations. One indicator of cardiac output may be the expired carbon dioxide (CO₂) partial pressure response to intravenous sodium bicarbonate (IVSB), which is rapidly converted to CO₂.

Methods

We conducted an initial evaluation of the relationship between expired CO₂ partial pressure and blood flow after a bolus of IVSB. To assess this relationship, we used a cardiopulmonary bypass circuit with predetermined blood flows in a laboratory trial and then assessed 18 patients undergoing surgery requiring cardiopulmonary bypass.

Results

For the laboratory portion of this pilot study, higher peak expired CO₂, faster time to reach peak, higher area under the curve, and greater kurtosis of peak were observed at higher cardiac output flow rates, and higher mean expired CO₂ was significantly associated with higher flow rates (p < 0.001). In the human study, higher mean (p = 0.023) and peak expired CO₂ (p = 0.028) were both significantly associated with higher cardiac output flow rates.

Conclusions

This technique may be a way to intermittently assess cardiac output or improve accuracy when used in conjunction with other continuous output monitors.

Innovation-Oriented Medical School Curricula: Review of the Literature

Innovation and entrepreneurship (I&E) programs in medical education have become available as medical schools recognize the need to train forward-thinking physicians. There is considerable diversity in the design and implementation of these curricula, which represents a challenge and possibly serves as a deterrent for the development of additional I&E programs. A comprehensive search of medical school I&E programs and review of all Association of American Medical Colleges member websites (n = 171) were conducted. This review sought to (1) identify all American and Canadian allopathic medical schools with I&E curricula, (2) evaluate their structure/integration in the context of medical education, (3) outline core learning themes, and (4) describe the evaluative metrics. Information was collected through published or publicly available websites and through a questionnaire sent to identified I&E program leaders. Twenty-eight I&E-oriented medical education programs were identified from 26 schools; all of the programs integrated faculty leadership with backgrounds in medicine, engineering, and/or business/entrepreneurship. Of the programs, 57% (16/28) had been launched within the past four years and 75% (21/28) based program enrollment on a selective application process. Nearly all (27/28) incorporated lecture series and/or hands-on modules as a teaching technique. The most prevalent metric was completion of a capstone project (22/28; 79%). At least 15.2% (26/171) of American and Canadian allopathic medical schools include the option for students to participate in an I&E curriculum-based program. This review can be used to help medical school faculty with developing I&E curricula.

Simulation-Based Assessment Identifies Longitudinal Changes in Cognitive Skills in an Anesthesiology Residency Training Program

OBJECTIVES

We describe observed improvements in nontechnical or "higher-order" deficiencies and cognitive performance skills in an anesthesia residency cohort for a 1-year time interval. Our main objectives were to evaluate higher-order, cognitive performance and to demonstrate that simulation can effectively serve as an assessment of cognitive skills and can help detect "higher-order" deficiencies, which are not as well identified through more traditional assessment tools. We hypothesized that simulation can identify longitudinal changes in cognitive skills and that cognitive performance deficiencies can then be remediated over time.

METHODS

We used 50 scenarios evaluating 35 residents during 2 subsequent years, and 18 of those 35 residents were evaluated in both years (post graduate years 3 then 4) in the same or similar scenarios. Individual basic knowledge and cognitive performance during simulation-based scenarios were assessed using a 20- to 27-item scenario-specific checklist. Items were labeled as basic knowledge/technical (lower-order cognition) or advanced cognitive/nontechnical (higher-order cognition). Identical or similar scenarios were repeated annually by a subset of 18 residents during 2 successive academic years. For every scenario and item, we calculated group error scenario rate (frequency) and individual (resident) item success. Grouped individuals' success rates are calculated as mean (SD), and item success grade and group error rates are calculated and presented as proportions. For all analyses, α level is 0.05.

RESULTS

Overall PGY4 residents' error rates were lower and success rates higher for the cognitive items compared with technical item performance in the operating room and resuscitation domains. In all 3 clinical domains, the cognitive error rate by PGY4 residents was fairly low (0.00-0.22) and the cognitive success rate by PGY4 residents was high (0.83-1.00) and significantly better compared with previous annual assessments (P < 0.05). Overall, there was an annual decrease in error rates for 2 years, primarily driven by decreases in cognitive errors. The most commonly observed cognitive error types remained anchoring, availability bias, premature closure, and confirmation bias.

CONCLUSIONS

Simulation-based assessments can highlight cognitive performance areas of relative strength, weakness, and progress in a resident or resident cohort. We believe that they can therefore be used to inform curriculum development including activities that require higher-level cognitive processing.

Case Report: Can Inhaled Adenosine Attenuate COVID-19?

This case report demonstrates a small repetition of the case series carried out in Italy wherein inhaled adenosine was administered to patients experiencing severe and worsening coronavirus disease-2019 (COVID-19). The two cases are important not only because they were the first of their type in the United States, but also because both patients were DNR/DNI and were therefore expected to die. Study repetition is vitally important in medicine. New work in pharmacology hypothesizes that adenosine-regulator proteins may play a role in the pathogenesis of COVID-19 infection. Furthermore, adenosine, by interacting with cell receptor sites, has pluripotent effects upon inflammatory cells, is anti-inflammatory, and is important in tissue hypoxia signaling. Inhaled adenosine is potentially safe; thousands have received it for asthmatic challenge testing. The effects of adenosine in these two cases were rapid, positive, and fit the pharmacologic hypotheses (as seen in prior work in this journal) and support its role as a therapeutic nucleoside.

Effects of a Single Rapid Infusion System on Platelet Function in Stored Whole Blood: An Ex Vivo Study

Introduction

Rapid infusion systems (RIS) are used to warm and rapidly infuse crystalloids and blood products. Current guidelines do not approve of platelet transfusion through a RIS, but data supporting these guidelines are scarce. Our hypothesis was that an infusion of whole blood through a RIS would degrade platelet quantity, impede viscoelastic clot strength, and inhibit platelet aggregation response to adenosine diphosphate pathway (ADP) activation.

Methods

Ten iterations of a simulated scenario of transfusing whole blood via a single brand and make of RIS (Belmont Fluid Management System 2000, Belmont Medical Technologies, Billerica, MA) were performed. Units of whole blood, which were two to nine days old, were leukoreduced prestorage. Blood was used to prime the RIS and then warmed and infused at 100 mL/min into a reservoir. Blood samples were collected before and immediately after infusion. Samples were tested for platelet count, size, and viscoelastic clot strength using thromboelastographic and aggregation assays.

Results

The study sample (n = 10) included platelets with an average age of 5.3 days. The infusion through the RIS had a detrimental effect on all the maximal amplitudes (MA) of viscoelastic testing: MA ADP (mean difference = −18.7 mm; 95% CI: −24.1 to −13.3, P = 0.004), MA rapid thromboelastography (MA rTEG) (mean difference = −6.0; 95% CI: −10.0 to −2.0, P = 0.008), MA TEG (mean difference = −7.1; 95% CI: −10.9 to −3.4, P = 0.004), mean platelet volume (MPV) (mean difference = −0.3; 95% CI: −0.6 to −0.1, P = 0.02), and platelet count (mean difference = −68.3 × 10³/µL; 95% CI: −86.9 to −49.7, P = 0.004).

Conclusions

Platelet quantity, viscoelastic clot strength, and platelet aggregation response to ADP each decline after infusion through a RIS. Further studies regarding microaggregates and platelet activation are required.

Isolation gowns as a potential work hazard

OBJECTIVES

Isolation gowns are used as a barrier to bacterial transmission from patient to provider and vice versa. If an isolation gown is ineffective, the patient and provider have a potential breach of safety and increased infection risk. This study compared the bacterial permeability of differently rated, commonly uses isolation gowns to assess their effectiveness in preventing simulated bacterial transmittance, and thus contamination, from patient to provider.

METHODS

Serial dilutions of Staphylococcus epidermidis in sterile saline were applied to a simulated skin surface. Unrated and Levels 1 through 4 non-sterile isolation gowns contacted the solution, simulating patient contact. Both sides of the contaminated gowns were then cultured on blood agar by rolling a sterile swab across the gown and evenly inoculating the culture plate. Colony counts from inside and outside of the gowns were compared. Separately, S. epidermidis was placed on a sample of each gown and scanning electron microscopy was used to visualize the contaminated gowns' physical structure.

RESULTS

Mean bacterial transmittance from outside of the gown (i.e. patient contact side) to inside of the gowns (i.e. provider clothing or skin side) based on gown rating was as follows: unrated: 50.4% (SD 9.0%); Level 1: 39.7% (SD 11.2%); Level 2: 16.3% (SD 10.3%); Level 3: 0.3% (SD 0.8%); Level 4: 0.0% (SD 0.0%). Scanning electron microscope imaging of unrated, Level 1, and Level 2 gowns revealed gown pore sizes much larger than the bacteria. The Welch one-way analysis of variance statistic showed significant difference dependent on gown-level rating.

CONCLUSIONS

Unrated, Level 1, and Level 2 isolation gowns do not provide effective bacterial isolation barriers when bacteria like S. epidermidis make contact with one side of the gown material. Not studied, but implied, is that unrated and lower rated isolation gowns would be as or even more physically permeable to virus particles, which are much smaller than bacteria.

A Flexible Enclosure to Protect Respiratory Therapists During Aerosol-Generating Procedures

BACKGROUND

Exposure of respiratory therapists (RTs) during aerosol-generating procedures such as endotracheal intubation is an occupational hazard. Depending on the hospital, RTs may serve as laryngoscopist or in a role providing ventilation support and initiating mechanical ventilation. This study aimed to evaluate the potential exposure of RTs serving in either of these roles.

METHODS

We set up a simulated patient with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in an ICU setting requiring endotracheal intubation involving a laryngoscopist, a nurse, and an RT supporting the laryngoscopist. All participants wore appropriate personal protective equipment (PPE). A fluorescent marker was sprayed by an atomizer during the procedure using 3 different methods for endotracheal intubation. The 3 techniques included PPE alone, a polycarbonate intubating box, or a coronavirus flexible enclosure, which consisted of a Mayo stand with plastic covering. The laryngoscopist and the supporting RT were assessed with a black light for contamination with the fluorescent marker. All simulations were recorded.

RESULTS

When using only PPE, both the laryngoscopist and the RT were grossly contaminated. When using the intubating box, the laryngoscopist's contamination was detectable only on the gloves: the gown and face shield remained uncontaminated; the RT was still grossly contaminated on the gloves, gown, neck, and face shield. When using the coronavirus flexible enclosure system, both the laryngoscopist and the RT were better protected, with contamination detected only on the gloves of the laryngoscopist and the RT.

CONCLUSIONS

Of the 3 techniques, the coronavirus flexible enclosure contained the fluorescent marker more effectively during endotracheal intubation than PPE alone or the intubating box based on exposure of the laryngoscopist and supporting RT. Optimizing containment during aerosol-generating procedures like endotracheal intubation is a critical component of minimizing occupational and nosocomial spread of SARS-CoV-2 to RTs who may serve as either the laryngoscopist or a support role.

The RITE of Passage: Learning Styles and Residency In-Service Training Examination (RITE) Scores

Introduction

The objective of the pilot study was to determine the association between learning preferences and improvement in the American Academy of Neurology Residency In-Service Training Examination (RITE) scores from postgraduate year 2 (PGY-2) to postgraduate year 3 (PGY-3) in neurology residents.

Methods

Neurology residents at the University of Florida were approached to participate, and their consent was obtained. VARK inventory, representing four modalities (visual, aural, read/write, kinesthetic) of learning preferences, was completed by participants. Participants could pick more than one modality. The number of responses in each sensory domain was recorded, with higher numbers indicating stronger preference. Residents’ performance on the RITE was recorded for PGY-2 and PGY-3.

Results

Seventeen residents completed the VARK inventory and 16 had data for RITE. Residents demonstrated overall positive change in RITE from PGY-2 to PGY-3 (mean change = 6%; 95%CI: 4%, 9%). The median number of responses was highest for the kinesthetic domain (median = 7, range = 1-12), followed by visual (median = 6, range = 2-12), aural (median = 4, range = 1-10), and read/write (median = 4, range = 1-10). Among VARK domains, the number of responses in read/write had the strongest correlation with mean change in RITE performance from PGY-2 to PGY-3 (r = 0.45; 95%CI: -0.08, 0.78); residents in the high read/write group (number of response above median) had greater mean change in RITE performance (9%; 95%CI: 6%, 12%) while those in the low read/write group showed little to no increase in RITE from PGY-2 to PGY-3 (2%; 95%CI: -1%, 6%).

Conclusions

Higher VARK survey responses in the read/write domain were related to greater change in RITE scores from PGY-2 to PGY-3. These findings seem intuitively obvious considering the format of the RITE. These pilot data permit further investigation of individual resident learning preference and how it relates to test performance. By understanding a resident’s learning style, both educators and the resident will have an awareness of areas that need to be improved to be successful, which may be via remedial curricula and self-study activities.

A Methyltransferase Inhibitor (Decitabine) Alleviates Intergenerational Effects of Paternal Neonatal Exposure to Anesthesia With Sevoflurane

BACKGROUND

Neonatal exposure to sevoflurane induces neurobehavioral and neuroendocrine abnormalities in exposed male rats (generation F0) and neurobehavioral, but not neuroendocrine, abnormalities in their male, but not female, offspring (generation F1). These effects of sevoflurane are accompanied by a hypermethylated neuron-specific K-2Cl (Kcc2) Cl exporter gene in the F0 spermatozoa and the F1 male hypothalamus, while the gene's expression is reduced in the F0 and F1 hypothalamus. We investigated whether inhibition of deoxyribonucleic acid methyltransferases (DNMTs) before paternal sevoflurane exposure could alleviate the anesthetic's F0 and F1 effects.

METHODS

Sprague-Dawley male rats were anesthetized with 2.1% sevoflurane for 5 hours on postnatal day (P) 5 and mated with control females on P90 to generate offspring. The nonselective DNMT inhibitor decitabine (0.5 mg/kg, intraperitoneally) was administered 30 minutes before sevoflurane exposure. The F0 and F1 male rats were evaluated in in vivo and in vitro tests in adulthood.

RESULTS

Paternal exposure to sevoflurane induced impaired prepulse inhibition of the acoustic startle response and exacerbated corticosterone responses to stress in F0 males and impaired prepulse inhibition of the startle responses in F1 males. These effects were accompanied in both generations by reduced and increased expressions of hypothalamic Kcc2 and Dnmt3a/b, respectively. Decitabine deterred the effects of paternal exposure to sevoflurane in F0 and F1 males.

CONCLUSIONS

These results suggest that similar decitabine-sensitive mechanisms regulating expression of multiple genes are involved in the mediation of neurobehavioral abnormalities in sires neonatally exposed to sevoflurane and in their future unexposed male offspring.

An online, interactive, screen-based simulator for learning basic EEG interpretation

OBJECTIVE

Develop and pilot test a simulator that presents ten commonly encountered representative clinical contexts for trainees to learn basic electroencephalogram (EEG) interpretation skills.

METHODS

We created an interactive web-based training simulator that allows self-paced, asynchronous learning and assessment of basic EEG interpretation skills. The simulator uses the information retrieval process via a free-response text box to enhance learning. Ten scenarios were created that present dynamic (scrolling) EEG tracings resembling the clinical setting, followed by questions with free-text answers. The answer was checked against an accepted word/phrase list. The simulator has been used by 76 trainees in total. We report pilot study results from the University of Florida's neurology residents (N = 24). Total percent correct for each scenario and average percent correct for all scenarios were calculated and correlated with most recent In-training Examination (ITE) and United States Medical License Examination (USMLE) scores.

RESULTS

Neurology residents' mean percent correct scenario scores ranged from 27.1-86.0% with an average scenario score of 61.2% ± 7.7. We showed a moderately strong correlation r = 0.49 between the ITE and the average scenario score.

CONCLUSION

We developed an online interactive EEG interpretation simulator to review basic EEG content and assess interpretation skills using an active retrieval approach. The pilot study showed a moderately strong correlation r = 0.49 between the ITE and the average scenario score. Since the ITE is a measure of clinical practice, this is evidence that the simulator can provide self-directed instruction and shows promise as a tool for assessment of EEG knowledge.

Neonatal exposure to sevoflurane expands the window of vulnerability to adverse effects of subsequent exposure to sevoflurane and alters hippocampal morphology via decitabine-sensitive mechanisms

BACKGROUND

Deficiencies in neurocognitive function have been found in late childhood or adolescence in patients who had prolonged and/or repeated early-life general anesthesia. Animal studies suggest that anesthetic-induced impairment in the neuron-specific K⁺-2Cl^- (Kcc2) Cl^- exporter expression, which regulates developmental maturation of GABA type A receptor (GABA_AR) signaling from excitatory to inhibitory, may play a mediating role. We tested whether the DNA methyltransferase (DNMT) inhibitor decitabine ameliorates the anesthetic's adverse effects.

METHODS

Sprague-Dawley male rats were injected with vehicle or decitabine 30 min before 2.1 % sevoflurane exposure for 5 h on postnatal day 5 (P5). On P19, P20, or P21, electroencephalography-detectable seizures were measured during 1 h of sevoflurane exposure, followed by collection of the trunk blood and brain tissue samples. Other rats were evaluated for changes in hippocampal CA1 dendrite morphology and gene expressions on ≥ P120.

RESULTS

Rats in the vehicle plus sevoflurane group responded to sevoflurane exposure on P19, P20 or P21 with electroencephalography-detectable seizures and stress-like corticosterone secretion and had altered hippocampal dendrite morphology in adulthood. These rats had expressions of Kcc2 and Dnmt genes downregulated and upregulated, respectively, in the P19 - P21 cortex and hypothalamus and the ≥ P120 hippocampus. All measured parameters in the sevoflurane-exposed rats that were pretreated with decitabine were not different from those in the control group.

CONCLUSIONS

Neonatal exposure to sevoflurane sensitizes rats to adverse effects of repeated exposure to the anesthetic. The anesthetic-caused changes in the decitabine-sensitive mechanisms may play a mediating role in the developmental effects of early-life anesthesia.

Roles of Testosterone and Estradiol in Mediation of Acute Neuroendocrine and Electroencephalographic Effects of Sevoflurane During the Sensitive Period in Rats

Testosterone (T), predominantly acting through its derivative 17β-estradiol (E2), regulates the brain's sexual differentiation in rodents during the perinatal sensitive period, which mirrors the window of vulnerability to the adverse effects of general anesthetics. The mechanisms of anesthesia's adverse effects are poorly understood. We investigated whether sevoflurane alters T and E2 levels and whether they contribute to sevoflurane's acute adverse effects in postnatal day 5 Sprague-Dawley rats. The rats underwent electroencephalography recordings for 2 h of baseline activity or for 1 h before and another hour during 2.1% sevoflurane exposure, followed by collection of trunk blood and brain tissue. Pharmacological agents, including the GABA type A receptor inhibitor bicuculline and the aromatase inhibitor formestane, were administered 30 min before sevoflurane anesthesia. Sevoflurane increased serum T levels in males only. All other effects of sevoflurane were similar in both sexes, including increases in serum levels of E2, hypothalamic mRNA levels of aromatase, estrogen receptor α (Erα) [not estrogen receptor β (Erβ)], Na⁺-K⁺-Cl^- cotransporter (Nkcc1)/K⁺-Cl^- cotransporter (Kcc2) mRNA ratio, electroencephalography-detectable seizures, and stress-like corticosterone secretion. Bicuculline and formestane alleviated these effects, except the T level increases. The ERα antagonist MPP, but not the ERβ antagonist PHTPP, reduced electroencephalography-detectable seizures and normalized the Nkcc1/Kcc2 mRNA ratio. Collectively, sevoflurane exacerbates levels of T in males and E2 in both sexes during the period of their organizational effects in rodents. Sevoflurane acts through GABA_AR-mediated, systemic T-independent elevation of E2 to cause electroencephalography-detectable seizures, stress-like corticosterone secretion, and changes in the expression of genes critical for brain development.

Visualization Improves Supraclavicular Access to the Subclavian Vein in a Mixed Reality Simulator

BACKGROUND

We investigated whether visual augmentation (3D, real-time, color visualization) of a procedural simulator improved performance during training in the supraclavicular approach to the subclavian vein, not as widely known or used as its infraclavicular counterpart.

METHODS

To train anesthesiology residents to access a central vein, a mixed reality simulator with emulated ultrasound imaging was created using an anatomically authentic, 3D-printed, physical mannequin based on a computed tomographic scan of an actual human. The simulator has a corresponding 3D virtual model of the neck and upper chest anatomy. Hand-held instruments such as a needle, an ultrasound probe, and a virtual camera controller are directly manipulated by the trainee and tracked and recorded with submillimeter resolution via miniature, 6 degrees of freedom magnetic sensors. After Institutional Review Board approval, 69 anesthesiology residents and faculty were enrolled and received scripted instructions on how to perform subclavian venous access using the supraclavicular approach based on anatomic landmarks. The volunteers were randomized into 2 cohorts. The first used real-time 3D visualization concurrently with trial 1, but not during trial 2. The second did not use real-time 3D visualization concurrently with trial 1 or 2. However, after trial 2, they observed a 3D visualization playback of trial 2 before performing trial 3 without visualization. An automated scoring system based on time, success, and errors/complications generated objective performance scores. Nonparametric statistical methods were used to compare the scores between subsequent trials, differences between groups (real-time visualization versus no visualization versus delayed visualization), and improvement in scores between trials within groups.

RESULTS

Although the real-time visualization group demonstrated significantly better performance than the delayed visualization group on trial 1 (P = .01), there was no difference in gain scores, between performance on the first trial and performance on the final trial, that were dependent on group (P = .13). In the delayed visualization group, the difference in performance between trial 1 and trial 2 was not significant (P = .09); reviewing performance on trial 2 before trial 3 resulted in improved performance when compared to trial 1 (P < .0001). There was no significant difference in median scores (P = .13) between the real-time visualization and delayed visualization groups for the last trial after both groups had received visualization. Participants reported a significant improvement in confidence in performing supraclavicular access to the subclavian vein. Standard deviations of scores, a measure of performance variability, decreased in the delayed visualization group after viewing the visualization.

CONCLUSIONS

Real-time visual augmentation (3D visualization) in the mixed reality simulator improved performance during supraclavicular access to the subclavian vein. No difference was seen in the final trial of the group that received real-time visualization compared to the group that had delayed visualization playback of their prior attempt. Training with the mixed reality simulator improved participant confidence in performing an unfamiliar technique.

The Effect of Modified Ultrafiltration on Serum Vancomycin Levels During Cardiopulmonary Bypass in Cardiac Surgery

OBJECTIVE

The aim of this study was to investigate whether the use of modified ultrafiltration at the end of cardiopulmonary bypass for cardiac surgical procedures significantly changes vancomycin serum concentrations.

DESIGN

Prospective study.

SETTING

Single tertiary cardiac center.

PARTICIPANTS

Twenty-six elective adult patients undergoing cardiac surgery with cardiopulmonary bypass from April 2014 to April 2015.

INTERVENTIONS

Serum vancomycin concentrations were measured just before cardiopulmonary bypass; during cardiopulmonary bypass at 5, 30, 60 minutes and then every 60 minutes; after completion of cardiopulmonary bypass before initiation of modified ultrafiltration; and at the end of modified ultrafiltration.

MEASUREMENTS AND MAIN RESULTS

Seventeen patients received modified ultrafiltration at the end of cardiopulmonary bypass. Serum vancomycin concentrations prior to cardiopulmonary bypass (45.9 ± 17.3 μg/mL) were significantly higher (P < 0.0001) than each time point following cardiopulmonary bypass (5 min 20.4 ± 6.4 μg/mL, 30 min 18.8 ± 5.4 μg/mL, 60 min 16.6 ± 4.9 μg/mL, and 120 min 14.3 ± 4.7 μg/mL). In the modified ultrafiltration group, serum vancomycin concentrations were 14.7 ± 4.6 μg/mL prior to modified ultrafiltration and 13.9 ± 4.3 μg/mL after ultrafiltration; this difference was statistically significant (P  =  0.0288). The mean modified ultrafiltration volume was 465 ± 158 mL.

CONCLUSIONS

Using modified ultrafiltration at the end of cardiopulmonary bypass significantly decreases serum vancomycin levels, but not by a clinically relevant amount. The decrease is to a concentration that is still significantly higher than the minimum inhibitory concentration for Staphylococcus epidermidis and Staphylococcus aureus; thus additional vancomycin administration is not recommended.

Effects of combined brief etomidate anesthesia and postnatal stress on amygdala expression of Cl- cotransporters and corticotropin-releasing hormone and alcohol intake in adult rats

Early life stressors, including general anesthesia, can have adverse effects on adult neural and behavioral outcomes, such as disruptions in inhibitory signaling, stress responsivity and increased risk of psychiatric disorders. Here we used a rat model to determine the effects of combined exposure to etomidate (ET) neonatal anesthesia and maternal separation on adult amygdala expression of genes for corticotropin-releasing hormone (Crh) and the chloride co-transporters Nkcc1 and Kcc2, as well as ethanol intake. Male and female Sprague-Dawley rats were subjected to 2 h of ET anesthesia on postnatal days (P) 4, 5, or 6 followed by maternal separation for 3 h on P10 (ET + SEP). During the P91-P120 period rats had daily 2 h access to three 0.05% saccharin solutions containing 0%, 5%, or 10% ethanol, followed by gene expression analyses. The ET + SEP group had increased Crh mRNA levels and Nkcc1/Kcc2 mRNA ratios in the amygdala, with greater increases in Nkcc1/Kcc2 mRNA ratios in males. A moderate increase in 5% ethanol intake was evident in the ET + SEP males, but not females, after calculation of the ratio of alcohol intake between the last week and first week of exposure. In contrast, control males tended to decrease alcohol consumption during the same period. A brief exposure to ET combined with a subsequent episode of stress early in life induced significant alterations in expression of amygdala Crh, Nkcc1 and Kcc2 with greater changes in the Cl^- transporter expression in males. The possibility of increased alcohol intake in the exposed males requires further confirmation using different alcohol intake paradigms.

Role of epigenetic mechanisms in transmitting the effects of neonatal sevoflurane exposure to the next generation of male, but not female, rats

BACKGROUND

Clinical studies report learning disabilities and attention-deficit/hyperactivity disorders in those exposed to general anaesthesia early in life. Rats, primarily males, exposed to GABAergic anaesthetics as neonates exhibit behavioural abnormalities, exacerbated responses to stress, and reduced expression of hypothalamic K+-2Cl- Cl- exporter (Kcc2). The latter is implicated in development of psychiatric disorders, including male predominant autism spectrum disorders. We tested whether parental early life exposure to sevoflurane, the most frequently used anaesthetic in paediatrics, affects the next generation of unexposed rats.

METHODS

Offspring (F1) of unexposed or exposed to sevoflurane on postnatal day 5 Sprague-Dawley rats (F0) were subjected to behavioural and brain gene expression evaluations.

RESULTS

Male, but not female, progeny of sevoflurane-exposed parents exhibited abnormalities in behavioural testing and Kcc2 expression. Male F1 rats of both exposed parents exhibited impaired spatial memory and expression of hippocampal and hypothalamic Kcc2. Offspring of only exposed sires had abnormalities in elevated plus maze and prepulse inhibition of startle, but normal spatial memory and impaired expression of hypothalamic, but not hippocampal, Kcc2. In contrast to exposed F0, their progeny exhibited normal corticosterone responses to stress. Bisulphite sequencing revealed increased CpG site methylation in the Kcc2 promoter in F0 sperm and F1 male hippocampus and hypothalamus that was in concordance with the changes in Kcc2 expression in specific F1 groups.

CONCLUSIONS

Neonatal exposure to sevoflurane can affect the next generation of males through epigenetic modification of Kcc2 expression, while F1 females are at diminished risk.

Clinical application of limiting laryngeal mask airway cuff pressures utilizing inflating syringe intrinsic recoil

BACKGROUND

Overinflation of the laryngeal mask airway (LMA) cuff may cause many of the complications associated with the use of the LMA. There is no clinically acceptable (cost effective and practical) method to ensure cuff pressure is maintained below the manufacturer's recommended maximum value of 60 cm H2O (44 mmHg). We studied the use of the intrinsic recoil of the LMA inflating syringe as an effective and practical way to limit cuff pressures at or below the manufacturer's recommended values.

METHODS

We enrolled 332 patients into three separate groups: LMAs inserted and inflated per standard practice at the institution with only manual palpation of the pilot balloon; LMA cuff pressures measured by a pressure transducer and reduced to < 60 cm H2O (44 mmHg); and LMA intra-cuff pressure managed by the intrinsic recoil of the syringe.

RESULTS

There were no statistically significant differences between the pressure transducer group and the syringe recoil group for initial cuff pressure or cuff pressure 1 hour after surgery. Both the syringe recoil group and pressure transducer group were less likely than the standard practice group to have sore throat and dysphagia 1 hour after surgery. These differences remained 24 hours after surgery.

CONCLUSIONS

Syringe recoil provides an efficient and reproducible method similar to manometry in preventing overinflation of the LMA cuff and decreasing the incidence of postoperative laryngopharyngeal complications.

Break Scrub to Take That Phone Call?

BACKGROUND

The American College of Surgeons reports that 60% of the hundreds of thousands of surgical site infections occurring annually are preventable. The practice of surgeons taking phone calls while remaining sterile in the operating field is often accomplished by interposing a sterile disposable towel between the phone and their glove. After completing the call, surgeons resume operating. The purpose of our study was to test the conceptual idea of whether bacteria transmit from an inanimate object, such as a telephone, to the gloves of a surgeon through a sterile disposable towel.

STUDY DESIGN

Glo Germ (Glo Germ Co), an ultraviolet light-enhanced particle powder sized to mimic bacteria, was placed on an inanimate surface and held with a sterile disposable operating room towel covering a sterile surgical glove. The glove was then inspected for Glo Germ using an ultraviolet light. Additionally, 18 operating room telephones were cultured and then held with a Sterile Disposable OR Towel (Medline Industries Inc) covering a sterile surgical glove. The surgical gloves were then cultured to determine if bacteria had transmitted from the telephone through the towel and onto the sterile glove.

RESULTS

The Glo Germ powder readily transmitted through the towel to the gloves. Median colony-forming units (CFU) on the cultured telephones for the 17 samples was 10, ranging from 1 to 35 CFUs. Of these 17 samples, 47% had transmission from the telephone to the glove, which was significantly greater than 0% (95% CI 26% to 69%, p < 0.001).

CONCLUSIONS

Sterile disposable operating room towels do not provide an effective barrier between bacteria present on operating room telephones and the otherwise sterile gloves of a surgeon.

Pre-emptive ice cube cryotherapy for reducing pain from local anaesthetic injections for simple lacerations: a randomised controlled trial

OBJECTIVE

Subcutaneous local anaesthetic injection can be painful to patients in the ED. We evaluated the effect of cryotherapy by application of an ice cube to the injection site prior to injection in patients with simple lacerations.

METHODS

We conducted a prospective, randomised, controlled trial in consented patients with simple lacerations needing primary repair at a single emergency centre from April to July 2016. We randomly assigned patients undergoing repair for simple lacerations to either the cryotherapy group or the control group (standard care; no cryotherapy or other pretreatment of the injection site). In cryotherapy group subjects, we applied an ice cube (size: 1.5×1.5×1.5 cm) placed inside a sterile glove on the wound at the anticipated subcutaneous lidocaine injection site for 2 min prior to injection. The primary outcome was a subjective numeric rating (0-10 scale) of the perceived pain from the subcutaneous local anaesthetic injections. Secondary outcomes were (a) perceived pain on a numeric scale for cryotherapy itself, that is, pain from contact of the ice cube/glove with the skin and (b) the rate of complications after primary laceration repair.

RESULTS

Fifty patients were enrolled, consented and randomised, with 25 in the cryotherapy group and 25 in the control group. The numeric rating scale for subcutaneous anaesthetic injections was median, IQR, 95% CI 2.0 (1 to 3.5), 1.81 to 3.47, respectively, in the cryotherapy group and 5.0 (3 to 7), 3.91 to 6.05 in the control group (Mann-Whitney U=147.50, p=0.001). No wound complications occurred in either group. The numeric rating scale for cryotherapy itself was median, IQR, 95% CI: 2.0 (1 to 3.5), 1.90 to 3.70.

CONCLUSION

Pre-emptive topical injection site cryotherapy lasting 2 min before subcutaneous local anaesthetic injections can significantly reduce perceived pain from subcutaneous local anaesthetic injections in patients presenting for simple laceration repair.

TRIAL REGISTRATION NUMBER

KCT0001990.

Role of environmental stressors in determining the developmental outcome of neonatal anesthesia

BACKGROUND

The majority of studies evaluating neurocognition in humans who had procedures under anesthesia early in life found long-term deficits even though the typical anesthesia duration normalized to the human life span is much shorter than that shown to induce developmental abnormalities in rodents. Therefore, we studied whether subsequent environmental stressors contribute to deficiencies programmed by a brief neonatal etomidate exposure.

METHODS

Postnatal days (P) 4, 5, or 6, Sprague-Dawley rats, pretreated with vehicle or the Na+-K+-2Cl- (NKCC1) inhibitor, bumetanide, received two injections of etomidate resulting in anesthesia for 2h. To simulate stress after anesthesia, the animals were exposed to a single maternal separation for 3h at P10. 3-7days after exposure to etomidate the rats had increased hypothalamic NKCC1 mRNA and corticotropin releasing hormone (CRH) mRNA and decreased K+-2Cl- (KCC2) mRNA levels with greater changes in males. In rats neonatally exposed to both etomidate and maternal separation, these abnormalities persisted into adulthood. These animals also exhibited extended corticosterone responses to restraint stress with increases in total plasma corticosterone more robust in males, as well as behavioral abnormalities. Pretreatment with the NKCC1 inhibitor ameliorated most of these effects.

CONCLUSIONS

Post-anesthesia stressors may exacerbate/unmask neurodevelopmental abnormalities even after a relatively short anesthetic with etomidate, leading to dysregulated stress response systems and neurobehavioral deficiencies in adulthood. Amelioration by bumetanide suggests a mechanistic role for etomidate-enhanced gamma-aminobutyric acid type A receptor-mediated depolarization in initiating long-lasting alterations in gene expression that are further potentiated by subsequent maternal separation.

Perfusion Index: An Indicator of Success During Endoscopic Thoracic Sympathectomy for Hyperhidrosis

BACKGROUND

Endoscopic thoracic sympathectomy (ETS) is indicated for refractory hyperhidrosis. The pulse oximetry-derived perfusion index (PI) quantifies pulsatile blood flow at the oximeter. Thoracic sympathectomy increases blood flow; thus we postulate it will reliably increase PI. We evaluated the ipsilateral finger PI as a predictor of successful sympathectomy during ETS.

METHODS

After institutional review board approval and informed consent, 100 adult patients undergoing bilateral ETS were studied. Finger and earlobe pulse oximetry probes were placed. Hemodynamic variables and PI were continuously monitored. PI data were collected before and every minute after sympathectomy for 5 minutes and then at 10 minutes. We defined a successful sympathectomy by at least a 50% increase of the PI on the ipsilateral arm. A repeated measures analysis of variance was conducted to determine overall model significance (p ≤ 0.05).

RESULTS

Left sympathectomy was associated with a mean 240% increase in PI (p < 0.0001) during the first consecutive 10 minutes, whereas the right side exhibited a mean 236% increase in PI (p < 0.0001). Statistically significant differences were observed between the mean baseline PI value ± the standard error of the mean and time intervals (1, 2, 3, 4, 5, and 10 minutes after baseline) on both the left and right sides for all time intervals. The hemodynamics remained constant throughout the study period. All patients had postoperative resolution of their hyperhidrosis symptoms.

CONCLUSIONS

In patients with hyperhidrosis of the upper extremities, intraoperative PI derived from an ipsilateral finger pulse oximeter is an intraoperative marker for successful thoracic sympathectomy.

Higher Fresh Gas Flow Rates Decrease Tidal Volume During Pressure Control Ventilation

BACKGROUND

We observed that increasing fresh gas flow (FGF) decreased exhaled tidal volume (VT) during pressure control ventilation (PCV). A literature search produced no such description whereby unintended VT changes occur with FGF changes during PCV.

METHODS

To model an infant's lungs, 1 lung of a mechanical lung model (Dual Adult TTL 1600; Michigan Instruments, Inc, Grand Rapids, MI) was set at a compliance of 0.0068 L/cm H2O. An Rp50 resistor (27.2 cm H2O/L/s at 15 L/min) simulated normal bronchial resistance. The simulated lung was connected to a pediatric breathing circuit via a 3.5-mm cuffed endotracheal tube. A ventilator with PCV capability (Model 7900; Aestiva, GE Healthcare, Madison, WI) measured exhaled VT, and a flow monitor (NICO; Respironics, Murraysville, PA) measured peak inspiratory flow, positive end-expiratory pressure (PEEP), and peak inspiratory pressure. In PCV mode, exhaled VT displayed by the ventilator at FGF rates of 1, 6, 10, and 15 L/min was manually recorded across multiple ventilator settings. This protocol was repeated for the Avance CS2 anesthesia machine (GE Healthcare).

RESULTS

For the Aestiva, higher FGF rates in PCV mode decreased exhaled VT. Exhaled VT for FGFs of 1, 6, 10, and 15 L/min were on average 48, 34.9, 16.5, and 10 mL, respectively, at ventilator settings of inspiratory pressure of 10 cm H2O, PEEP of 0 cm H2O, and respiratory rate of 20 breaths/min. This is a decrease by up to 27%, 65.6%, and 79.2% when FGFs of 6, 10, and 15 L/min are compared with a FGF of 1 L/min, respectively. In the GE Avance CS2 at the same ventilator settings, VT for FGF rates of 1, 6, 10, and 15 L/min were on average 46, 43, 40.4, and 39.7 mL, respectively. The FGF effect on VT was not as pronounced with the GE Avance CS2 as with the GE Aestiva.

CONCLUSIONS

FGF has a significant effect on VT during PCV in the Aestiva bellows ventilator, suggesting caution when changing FGF during PCV in infants. Our hypothesis is that at higher FGF rates, an inadvertent PEEP is developed by the flow resistance of the ventilator relief valve that is not recognized by the ventilator. In turn, less change in pressure is needed to reach the set inspiratory pressure, resulting in lower VT delivery at higher FGF rates. This underappreciated FGF-VT interaction during PCV with a bellows ventilator may be clinically significant in pediatric patients; prospective data collection in patients is needed for further evaluation.

Acute and Chronic Kidney Disease and Cardiovascular Mortality After Major Surgery

OBJECTIVE

The aim of the study was to determine the long-term cardiovascular-specific mortality in patients with acute kidney injury (AKI) or chronic kidney disease (CKD) after major surgery.

BACKGROUND

In surgical patients, pre-existing CKD and postoperative AKI are associated with increases in all-cause mortality.

METHODS

In a single-center cohort of 51,457 adult surgical patients undergoing major inpatient surgery, long-term cardiovascular-specific mortality was modeled using a multivariable subdistributional hazards model while treating any other cause of death as a competing risk and accounting for the progression to end-stage renal disease (ESRD) after discharge. Pre-existing CKD and ESRD, and postoperative AKI were the main independent predictors.

RESULTS

Before the admission, 4% and 8% of the cohort had pre-existing ESRD and CKD not requiring renal replacement therapy, respectively. During hospitalization, 39% developed AKI. At 10-year follow-up, adjusted cardiovascular-specific mortality estimates were 6%, 11%, 12%, 19%, and 27% for patients with no kidney disease, AKI with no CKD, CKD with no AKI, AKI with CKD, and ESRD, respectively (P < 0.001). This association remained after excluding 916 patients who progressed to ESRD after discharge, although it was significantly amplified among them. Compared with patients having no kidney disease, adjusted hazard ratios for cardiovascular mortality were significantly higher among patients with kidney disease, ranging from 1.95 (95% confidence interval, 1.80-2.11) for patients with de novo AKI to 5.70 (95% confidence interval, 5.00-6.49) for patients with pre-existing ESRD.

CONCLUSIONS

Both AKI and CKD were associated with higher long-term cardiovascular-specific mortality compared with patients having no kidney disease.

[Injuries to blood vessels near the heart caused by central venous catheters]

Injuries to blood vessels near the heart can quickly become life-threatening and include arterial injuries during central venous puncture, which can lead to hemorrhagic shock. We report 6 patients in whom injury to the subclavian artery and vein led to life-threatening complications. Central venous catheters are associated with a multitude of risks, such as venous thrombosis, air embolism, systemic or local infections, paresthesia, hemothorax, pneumothorax, and cervical hematoma, which are not always immediately discernible. The subclavian catheter is at a somewhat lower risk of catheter-associated sepsis and symptomatic venous thrombosis than approaches via the internal jugular and femoral veins. Indeed, access via the subclavian vein carries a substantial risk of pneumo- and hemothorax. Damage to the subclavian vein or artery can also occur during deliberate and inadvertent punctures and result in life-threatening complications. Therefore, careful consideration of the access route is required in relation to the patient and the clinical situation, to keep the incidence of complications as low as possible. For catheterization of the subclavian vein, puncture of the axillary vein in the infraclavicular fossa is a good alternative, because ultrasound imaging of the target vessel is easier than in the subclavian vein and the puncture can be performed much further from the lung.

No-fault compensation for ventilator-dependent children: a reasonable settlement value for lifetime attendant care

Severe neurological outcomes sustained in childhood often result in lifetime health care needs that are beyond the financial means of most families. When severe neurological deficits are alleged to have resulted from professional negligence, relief may be sought through litigation; however, the American tort system often yields inconsistent results or no compensation for patients. We sought to identify a reasonable, objective, and data-based monetary range for a no-fault compensation system with high- and low-financial limits for those with severe neurological deficits. Based on documented life expectancies and attendant care cost studies, the data analysis indicates a no-fault settlement payment ranging from US$479,712.24 to $3,098,504.16, reasonably ensures care and services for life.