Hypoxia, hypercarbia, and mortality reporting in studies of anaesthesia-related neonatal neurodevelopmental delay in rodent models: A systematic review.

BACKGROUND: The concept of anaesthesia-related neonatal neurotoxicity originated in neonatal rodent models, yet prospective clinical studies have largely not supported this concern. OBJECTIVES: To determine the frequency and magnitude of hypercarbia, hypoxia and death in rodent models of neonatal anaesthetic toxicity and neurodevelopmental delay. DESIGN: Systematic review of published rodent studies of neonatal anaesthesia neurotoxicity. We documented anaesthetic, route, dose, frequency and duration of exposures. We further report ventilation method, documentation of adequacy of ventilation [arterial blood gas (ABG), other], mortality and the reporting of mortality. DATA SOURCES: A PubMed literature search from 2003 to 2017 was conducted to identify studies on neurotoxicity in neonatal rodent models. ELIGIBILITY: Studies were included when at least one group of animals fell within the postnatal age range of 3 to 15 days. Only English language original studies published as full-length articles in peer reviewed journals were included in the final analysis. RESULTS: One hundred and three manuscripts were included. Ninety-eight percent of studies were conducted using spontaneous ventilation (101/103), with ABG monitoring used in only 33% of studies and visual monitoring alone for respiratory distress or cyanosis was employed in 60%. Of the 33% who reported ABG results, there were widely divergent values, with most reporting modest-to-severe hypercarbia. Mortality (median 11%, range of 0 to 40%), which infers severe hypoxia, was documented in only 36/103 (35%) reports. CONCLUSION: Hypoxia and hypercarbia have known apoptotic effects on developing brains. Hence, the inadequate control of hypercarbia and hypoxia in neonatal rodent models of anaesthetic exposure during spontaneous ventilation suggests that the evidence for developmental delay and neurotoxicity attributed to anaesthesia may not be valid in humans.

Use of gelatin puzzle phantoms to teach medical students isolated ultrasound transducer movements and fundamental concepts.

BACKGROUND: Psychomotor skills related to the use of medical ultrasound are a fundamental, but often overlooked component of this ubiquitous medical imaging technology. Although discussions of image production/orientation, sonographic planes, and imaging/scanning techniques are common in existing literature, these discussions rarely address practical skills related to these basic concepts. The cognitive load of transducer movements and machine operation, in conjunction with learning the ultrasound representation of anatomy, may overwhelm a novice learner. Our goal was to develop and evaluate a set of ultrasound puzzle phantoms for students to use as they learn isolated, specific transducer movements and sonographic concepts. We intentionally created phantoms that contain objects that are likely familiar to students to reduce the cognitive load associated with simultaneously learning the ultrasound interpretation of anatomy. METHODS: This preliminary evaluation of our novel, homemade, gelatin ultrasound puzzle phantoms was performed using pretests and posttests obtained by scanning an assessment phantom, and student questionnaires. Two phases of training and testing occurred with feedback from Phase 1 allowing for refinement of the puzzles and techniques for testing. Skills taught and evaluated included probe rotation, depth assessment, sliding, and tilting. RESULTS: Twenty-eight students attended the Phase 1 training session with positive trends in students' abilities to use rotation, sliding, and tilting to answer questions, while only depth showed statistically significant improvements (p = 0.021). Overall students agreed the experience a productive use of time (86%), was beneficial (93%), and would recommend to others (93%). Fifteen (54%) students returned 3 months later. There was no significant decay in skills obtained from the prior training session. In Phase 2, 134 medical students participated, and 76 (57%) completed an online questionnaire. A majority of students agreed they had a better understanding of rotation (83%), depth (80%), sliding (88%) and tilting (55%). Similar to Phase 1, many students (75%) felt the experience was beneficial. CONCLUSIONS: This preliminary study gave us insight into student opinions, as well as information to guide future scalability and development of additional ultrasound puzzle phantoms to aid in medical student education of isolated transducer movements and sonographic concepts prior to imaging human anatomy.

An exploratory study of the relationship between postoperative nausea and vomiting and postdischarge nausea and vomiting in children undergoing ambulatory surgery.

BACKGROUND: The factors contributing to postoperative nausea and vomiting in children have been identified, but there have been no reported studies that have studied pediatric postdischarge nausea and vomiting. AIMS: This preliminary study aimed to identify  the factors affecting postdischarge nausea and vomiting in ambulatory children, specifically whether postoperative nausea and vomiting factors are contributory. METHODS: One hundred and twenty-two pediatric patients aged 5-10 years undergoing elective ambulatory surgery participated in this institution-approved study. After obtaining written parental consent and patient assent when indicated, child self-ratings of nausea and pain were completed preoperatively and at discharge, and for 3 days postdischarge. Questionnaires were returned by mail, with a 64% return rate. Using stepwise logistic regression with backward elimination, three separate analyses were undertaken to predict the following outcomes: nausea present in recovery, nausea present on postoperative day 1, and emesis on day of surgery. RESULTS: Nearly half (47%) of our cohort experienced nausea at the time of discharge; 11% had emesis on day of surgery. On postoperative day 1, there was a 15% incidence of nausea with a 3% incidence of emesis. In the multiple logistic regression analyses, nausea at discharge was predicted by male gender (odds ratio 2.5, 95% CI: 1.0-6.2) and the presence of pain on discharge (odds ratio 3.0, 95% CI: 1.0-9.2). Emesis on day of surgery was predicted by the presence of nausea at discharge (odds ratio 16.9, 95% CI: 1.8-159.3) and having a family history of nausea/vomiting (odds ratio 8.3, 95% CI: 1.6-43.4). The presence of nausea on postoperative day 1 was predicted only by the presence of nausea on discharge (odds ratio 3.7, 95% CI: 1.2-11.1). CONCLUSION: Our preliminary data indicate that postoperative nausea and vomiting may persist into the postdischarge period and pain may be a contributing factor.

Integration of a Low-Cost Introductory Ultrasound Curriculum Into Existing Procedural Skills Education for Preclinical Medical Students.

We evaluated integration of an introductory ultrasound curriculum into our existing mandatory procedural skills program for preclinical medical students. Phantoms consisting of olives, pimento olives, and grapes embedded in opaque gelatin were developed. Four classes encouraged progressive refinement of phantom-scanning and object identification skills. Students improved their ability to identify hidden objects, although each object type achieved a statistically significant improvement in correct identification at different time points. The total phantom cost per student was $0.76. Our results suggest that short repeated experiences scanning simple, low-cost ultrasound phantoms confer basic ultrasound skills.

Assessment of clinical reasoning: A Script Concordance test designed for pre-clinical medical students.

BACKGROUND: The Script Concordance test (SCT) measures clinical reasoning in the context of uncertainty by comparing the responses of examinees and expert clinicians. It uses the level of agreement with a panel of experts to assign credit for the examinee's answers. AIM: This study describes the development and validation of a SCT for pre-clinical medical students. METHODS: Faculty from two US medical schools developed SCT items in the domains of anatomy, biochemistry, physiology, and histology. Scoring procedures utilized data from a panel of 30 expert physicians. Validation focused on internal reliability and the ability of the SCT to distinguish between different cohorts. RESULTS: The SCT was administered to an aggregate of 411 second-year and 70 fourth-year students from both schools. Internal consistency for the 75 test items was satisfactory (Cronbach's alpha = 0.73). The SCT successfully differentiated second- from fourth-year students and both student groups from the expert panel in a one-way analysis of variance (F(2,508) = 120.4; p < 0.0001). Mean scores for students from the two schools were not significantly different (p = 0.20). CONCLUSION: This SCT successfully differentiated pre-clinical medical students from fourth-year medical students and both cohorts of medical students from expert clinicians across different institutions and geographic areas. The SCT shows promise as an easy-to-administer measure of "problem-solving" performance in competency evaluation even in the beginning years of medical education.

Intraoperative airway obstruction related to tracheostomy tube malposition in a patient with achondroplasia and Jeune's syndrome.

A 14 year-old adolescent with achondroplasia and Jeune's syndrome (asphyxiating thoracic dystrophy) presented for cervical spine surgery in the prone position. Due to the need for home mechanical ventilation at night, the patient had a tracheostomy in place. With the first surgical procedure, the cuffed tracheostomy tube was left in place during prone positioning. Difficulties encountered with ventilation through the cuffed tracheostomy tube in the prone position necessitated aborting the case. During three subsequent surgeries, the tracheostomy tube was removed and an armored endotracheal tube was placed through the tracheostomy stoma prior to prone positioning. No further difficulties with ventilation were noted with the subsequent cases. There are currently no guidelines in the medical literature regarding perioperative management of patients with a tracheostomy requiring prone positioning for surgery. The management of such patients is reviewed and possible problems with tracheostomy positioning during prone positioning are explored. Given such issues, we would suggest removal of the tracheostomy tube and placement of an armored endotracheal tube through the stoma during surgical procedures in the prone position.

Transcutaneous CO2 versus end-tidal CO2 in neonates and infants undergoing surgery: a prospective study.

Aim: End-tidal CO2 (EtCO2) is the standard in operative care along with pulse oximetry for ventilation assessment. It is known to be less accurate in the infant population than in adults. Many neonatal intensive care units (NICU) have converted to utilizing transcutaneous CO2 (tcPCO2) monitoring. This study aimed to compare perioperative EtCO2 to tcPCO2 in the pediatric perioperative population specifically below 10 kg, which encompasses neonates and some infants. Methods: After IRB approval and parental written informed consent, we enrolled neonates and infants weighing less than 10 kg, who were scheduled for elective surgery with endotracheal tube under general anesthesia. PCO2 was monitored with EtCO2 and with tcPCO2. Venous blood gas (PvCO2) samples were drawn at the end of the anesthetic. We calculated a mean difference of EtCO2 minus PvCO2 (Delta EtCO2), and tcPCO2 minus PvCO2 (Delta tcPCO2) from end-of-case measurements. The mean differences in the NICU and non-NICU patients were compared by t-tests and Bland-Altman analysis. Results: Median age was 10.9 weeks, and median weight was 4.4 kg. NICU (n=6) and non-NICU (n=14) patients did not differ in PvCO2. Relative to the PvCO2, the Delta EtCO2 was much greater in the NICU compared to the non-NICU patients (-28.1 versus -9.8, t=3.912, 18 df, P=0.001). Delta tcPCO2 was close to zero in both groups. Although both measures obtained simultaneously in the same patients agreed moderately with each other (r =0.444, 18 df, P=0.05), Bland-Altman plots indicated that the mean difference (bias) in EtCO2 measurements differed significantly from zero (P<0.05). Conclusions: EtCO2 underestimates PvCO2 values in neonates and infants under general anesthesia. TcPCO2 closely approximates venous blood gas values, in both the NICU and non-NICU samples. We, therefore, conclude that tcPCO2 is a more accurate measure of operative PvCO2 in infants, especially in NICU patients.

Successful intraoperative spinal cord monitoring during scoliosis surgery using a total intravenous anesthetic regimen including dexmedetomidine.

Intraoperative neurophysiological monitoring (IONM) during corrective spinal surgery is widely used. Because of the possible interference with the recording of evoked potentials by inhalational anesthetics, total intravenous anesthetic (TIVA) regimens have been advocated. TIVA regimens may be difficult to use in pediatric populations due to metabolic factors. We report on the results of multimodality IONM during 18 cases in which a TIVA regimen incorporating dexmedetomidine (Precedex, Hespira, Lake Forest, IL) was used. Monitoring techniques included sensory (SSEP) and motor evoked potentials (MEP), as well as pedicle screw stimulation. SSEPs were maintained within an acceptable range of baseline amplitude (50%) and latency (10%), and MEPs remained elicitable throughout each case. We therefore found that the anesthetic regimen did not significantly interfere with any of the monitoring modalities used and conclude that IONM in the presence of dexmedetomidine is feasible under appropriate conditions.

Organization of sensory input to the nociceptive-specific cutaneous trunk muscle reflex in rat, an effective experimental system for examining nociception and plasticity.

Detailed characterization of neural circuitries furthers our understanding of how nervous systems perform specific functions and allows the use of those systems to test hypotheses. We have characterized the sensory input to the cutaneous trunk muscle (CTM; also cutaneus trunci [rat] or cutaneus maximus [mouse]) reflex (CTMR), which manifests as a puckering of the dorsal thoracolumbar skin and is selectively driven by noxious stimuli. CTM electromyography and neurogram recordings in naïve rats revealed that CTMR responses were elicited by natural stimuli and electrical stimulation of all segments from C4 to L6, a much greater extent of segmental drive to the CTMR than previously described. Stimulation of some subcutaneous paraspinal tissue can also elicit this reflex. Using a selective neurotoxin, we also demonstrate differential drive of the CTMR by trkA-expressing and nonexpressing small-diameter afferents. These observations highlight aspects of the organization of the CTMR system that make it attractive for studies of nociception and anesthesiology and plasticity of primary afferents, motoneurons, and the propriospinal system. We use the CTMR system to demonstrate qualitatively and quantitatively that experimental pharmacological treatments can be compared with controls applied either to the contralateral side or to another segment, with the remaining segments providing controls for systemic or other treatment effects. These data indicate the potential for using the CTMR system as both an invasive and a noninvasive quantitative assessment tool providing improved statistical power and reduced animal use.

Summer anesthesiology externship: Demonstrating the ability of early clinical involvement to educate and increase specialty interest.

BACKGROUND: We describe the influence of a 6-week "Summer Anesthesiology Externship" featuring didactic, procedure, and simulation education on formation of medical students' specialty choice. METHODS: Eighteen months after externship completion, externs were sent a questionnaire with Likert scale agreement ratings of subspecialties/simulations and yes/no questions about student career interests before/after the program, stipend importance, and procedural skill performance during/after the program. RESULTS: General anesthesiology had the highest subspecialty approval rating (9.0). Externs strongly agreed that simulations successfully progressed at first year student understanding levels (9.2 mean agreement rating), increased confidence in being part of a care team (9.4 mean agreement rating), and provided personal/interpersonal development. Externs unanimously agreed that the program introduced them to the breadth of anesthesiology, and that practicing clinical/procedural skills improved confidence when performing the procedures later in medical school. Four of 14 students applied for the externship with some focus on anesthesiology as a career choice. After the externship, a significantly higher number of students (12 of 14) were strongly considering applying to the field (p<0.0001). Eleven of 14 ultimately entered anesthesiology residencies, a significantly higher rate than our general medical student classes (p<0.0001). CONCLUSIONS: Both CA1 and CA3 resident post-test scores improved at the end of the ultrasound guided regional workshop. Our study showed a 68% improvement in test scores, which is larger than the 50% improvement previously reported. These results show that fast learning can occur in this type of setting. Furthermore, knowledge acquired during the workshop was retained when CA1 residents were re-tested one year after the workshop. The ultrasound-guided regional anesthesia workshop will become part of the didactic series for our CA1 residents and will be a required learning activity. Additional work still needs to be done to find out the best way to test knowledge and skill outcomes in residents learning new technology and techniques.

Teaching systems-based competency in anesthesiology residency: development of an education and assessment tool.

BACKGROUND: The Accreditation Council for Graduate Medical Education requires programs to educate and evaluate residents in 6 competencies, including systems-based practice. We designed a survey and assessment tool to address the competency as it pertains to anesthetic drug costs in an academic center. METHODS: Residents, certified registered nurse anesthetists, and faculty were asked to complete an anesthetic drug-cost survey without relying on reference materials. After a combination of compulsory in-class didactic sessions and web-based education, the participants were asked to design an anesthetic, give example cases, and determine costs. The initial task was repeated 1 year later. RESULTS: Our preintervention survey revealed that most practitioners knew very little about anesthetic drug costs, regardless of level of training or degree. All residents completed the mandatory online education tool, more than 80% attended the departmental grand rounds program, and 100% met the goal of designing an anesthetic for all cases within the preset price limit. A repeat of the cost estimate produced an improvement in cost estimates with reduction in variability (P < .05, Student unpaired t test), although estimates of volatile anesthetic and reversal agent costs did not achieve significance at the .05 level for any of the 3 cases. CONCLUSION: Introducing a formalized teaching and assessment tool has improved our residents' understanding of anesthetic drug costs, and improved our ability to teach and assess the systems-based practice competency.