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.

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.

Trajectories of Brain Lactate and Re-visited Oxygen-Glucose Index Calculations Do Not Support Elevated Non-oxidative Metabolism of Glucose Across Childhood.

Brain growth across childhood is a dynamic process associated with specific energy requirements. A disproportionately higher rate of glucose utilization (CMRglucose) compared with oxygen consumption (CMRO2) was documented in children's brain and suggestive of non-oxidative metabolism of glucose. Several candidate metabolic pathways may explain the CMRglucose-CMRO2 mismatch, and lactate production is considered a major contender. The ~33% excess CMRglucose equals 0.18 µmol glucose/g/min and predicts lactate release of 0.36 µmol/g/min. To validate such scenario, we measured the brain lactate concentration ([Lac]) in 65 children to determine if indeed lactate accumulates and is high enough to (1) account for the glucose consumed in excess of oxygen and (2) support a high rate of lactate efflux from the young brain. Across childhood, brain [Lac] was lower than predicted, and below the range for adult brain. In addition, we re-calculated the CMRglucose-CMRO2 mismatch itself by using updated lumped constant values. The calculated cerebral metabolic rate of lactate indicated a net influx of 0.04 µmol/g/min, or in terms of CMRglucose, of 0.02 µmol glucose/g/min. Accumulation of [Lac] and calculated efflux of lactate from brain are not consistent with the increase in non-oxidative metabolism of glucose. In addition, the value for the lumped constant for [18F]fluorodeoxyglucose has a high impact on calculated CMRglucose and use of updated values alters or eliminates the CMRglucose-CMRO2 mismatch in developing brain. We conclude that the presently-accepted notion of non-oxidative metabolism of glucose during childhood must be revisited and deserves further investigations.

Results of a Flipped Classroom Teaching Approach in Anesthesiology Residents.

BACKGROUND: In a flipped classroom approach, learners view educational content prior to class and engage in active learning during didactic sessions. OBJECTIVE: We hypothesized that a flipped classroom improves knowledge acquisition and retention for residents compared to traditional lecture, and that residents prefer this approach. METHODS: We completed 2 iterations of a study in 2014 and 2015. Institutions were assigned to either flipped classroom or traditional lecture for 4 weekly sessions. The flipped classroom consisted of reviewing a 15-minute video, followed by 45-minute in-class interactive sessions with audience response questions, think-pair-share questions, and case discussions. The traditional lecture approach consisted of a 55-minute lecture given by faculty with 5 minutes for questions. Residents completed 3 knowledge tests (pretest, posttest, and 4-month retention) and surveys of their perceptions of the didactic sessions. A linear mixed model was used to compare the effect of both formats on knowledge acquisition and retention. RESULTS: Of 182 eligible postgraduate year 2 anesthesiology residents, 155 (85%) participated in the entire intervention, and 142 (78%) completed all tests. The flipped classroom approach improved knowledge retention after 4 months (adjusted mean = 6%; P = .014; d = 0.56), and residents preferred the flipped classroom (pre = 46%; post = 82%; P < .001). CONCLUSIONS: The flipped classroom approach to didactic education resulted in a small improvement in knowledge retention and was preferred by anesthesiology residents.

Brain maturation in neonatal rodents is impeded by sevoflurane anesthesia.

BACKGROUND: A wealth of data shows neuronal demise after general anesthesia in the very young rodent brain. Herein, the authors apply proton magnetic resonance spectroscopy (1HMRS), testing the hypothesis that neurotoxic exposure during peak synaptogenesis can be tracked via changes in neuronal metabolites. METHODS: 1HMRS spectra were acquired in the brain (thalamus) of neonatal rat pups 24 and 48 h after sevoflurane exposure on postnatal day (PND) 7 and 15 and in unexposed, sham controls. A repeated measure ANOVA was performed to examine whether changes in metabolites were different between exposed and unexposed groups. Sevoflurane-induced neurotoxicity on PND7 was confirmed by immunohistochemistry. RESULTS: In unexposed PND7 pups (N = 21), concentration of N-acetylaspartate (NAA; [NAA]) increased by 16% from PND8 to PND9, whereas in exposed PND7 pups (N = 19), [NAA] did not change and concentration of glycerophosphorylcholine and phosphorylcholine ([GPC + PCh]) decreased by 25%. In PND15 rats, [NAA] increased from PND16 to PND17 for both the exposed (N = 14) and the unexposed (N = 16) groups. Two-way ANOVA for PND7 pups demonstrated that changes over time observed in [NAA] (P = 0.031) and [GPC + PCh] (P = 0.024) were different between those two groups. CONCLUSIONS: The authors demonstrated that normal [NAA] increase from PND8 to PND9 was impeded in sevoflurane-exposed rats when exposed at PND7; however, not impeded when exposed on PND15. Furthermore, the authors showed that noninvasive 1HMRS is sufficiently sensitive to detect subtle differences in developmental time trajectory of [NAA]. This is potentially clinically relevant because 1HMRS can be applied across species and may be useful in providing evidence of neurotoxicity in the human neonatal brain.

Metabolomic profiling of children's brains undergoing general anesthesia with sevoflurane and propofol.

BACKGROUND: We recently applied proton magnetic resonance spectroscopy (HMRS) to investigate metabolic consequences of general anesthesia in the rodent brain, and discovered that isoflurane anesthesia was characterized by higher concentrations of lactate, glutamate, and glucose in comparison with propofol. We hypothesized that the metabolomic differences between an inhalant and intravenous anesthetic observed in the rodent brain could be reproduced in the human brain. METHODS: HMRS-based metabolomic profiling was applied to characterize the cerebral metabolic status of 59 children undergoing magnetic resonance imaging during anesthesia with either sevoflurane or propofol. HMRS scans were acquired in the parietal cortex after approximately 60 min of anesthesia. Upon emergence the children were assessed using the pediatric anesthesia emergence delirium scale. RESULTS: With sevoflurane anesthesia, the metabolic signature consisted of higher concentrations of lactate and glucose compared with children anesthetized with propofol. Further, a correlation and stepwise regression analysis performed on emergence delirium scores in relation to the metabolic status revealed that lactate and glucose correlated positively and total creatine negatively with the emergence delirium score. CONCLUSIONS: Our results demonstrating higher glucose and lactate with sevoflurane in the human brain compared with propofol could reflect greater neuronal activity with sevofluane resulting in enhanced glutamate-neurotransmitter cycling, increased glycolysis, and lactate shuttling from astrocytes to neurons or mitochondrial dysfunction. Further, the association between emergence delirium and lactate suggests that anesthesia-induced enhanced cortical activity in the unconscious state may interfere with rapid return to "coherent" brain connectivity patterns required for normal cognition upon emergence of anesthesia.

MR imaging-related electrical thermal injury complicated by acute carpal tunnel and compartment syndrome: case report.

Magnetic resonance (MR) imaging is generally considered a safe procedure. Contraindications include the presence of foreign objects in or on the body, which may be subject to electromagnetic fields associated with the MR system. Most of these objects are well known and are routinely screened for prior to the procedure. The authors report an unusual adverse event that appears to have been caused by a unique combination of factors involving an identification bracelet, an item not previously known to present any risks. To the authors' knowledge, this is the first report in the literature of a severe electrical thermal burn that required surgical intervention. Identification bracelets may need to be removed or padded to prevent direct contact with the patient's skin during all MR imaging examinations for patients unable to communicate, such as those requiring sedation or general anesthesia. (c) RSNA, 2010.

Fracture repair: modulation of fracture-callus and mechanical properties by sequential application of IL-6 following PTH 1-34 or PTH 28-48.

Fracture healing presents a sequence of three major stages: inflammation and granulation tissue formation, callus formation and remodeling. Our working hypothesis was that fracture-repair might be enhanced by stimulating proliferation of chondrocytes and osteoblasts in the early stages of fracture healing followed by sequential acceleration of the remodeling process. In the present study we employed a novel device developed by us implementing a standardized fracture in rat tibiae. We investigated the effect of PTH 28-48 or PTH 1-34 alone or in sequence combination with IL-6 together with its soluble receptor (IL-6sR) on fracture repair. PTH 28-48 or PTH 1-34 was applied locally into the hematoma of fractures on days 4, 5 and 6 and IL-6+ its soluble receptor on days 7, 9, and 11. Post-fracture callus volume as measured 14 days post-fracture was increased significantly only by PTH 1-34 (20%; P<0.01). When one of the PTH fragments and IL-6+IL-6sR were applied sequentially callus volume was increased significantly (33%; P<0.01). X-rays radiography at 5 weeks post-fracture showed enlarged callus volume following treatment by either PTH fragments alone, and complete union following the sequential injection of both PTH fragments and IL-6+IL-6sR, only. Only the combination of one of the PTH fragments with IL-6+IL-6sR, as measured 6 weeks post-fracture by three point bending, changed dramatically the quality of the regenerating bone as presented by a 300% increase in mechanical resistance when PTH 1-34 was combined and 200% when PTH 28-48 was combined relative to vehicle-treated fractured bones. We conclude that the sequential application of IL-6+IL-6sR with both PTH fragments has the potential of enhancing fracture healing in long bones and should be further explored in preclinical and in clinical studies.

Nontraumatic clostridial myonecrosis: an indication for colonoscopy?

Clostridial myonecrosis (CM) is a rare infection that usually arises after traumatic injury. Spontaneous or nontraumatic CM is even more rare and has been described in association with colorectal malignancy. These infections carry a high mortality rate and require urgent surgical intervention and intensive antibiotic therapy. This report describes a patient who presented with nontraumatic CM of the lower extremity in association with adenocarcinoma of the cecum.