Nasal high-flow oxygen delivery in children with abnormal airways.

BACKGROUND: Transnasal Humidified Rapid-Insufflation Ventilatory Exchange has been shown to safely prolong the safe apnea time in well children post induction of anesthesia and is rapidly becoming a new standard for apneic oxygenation in adults. The same oxygenation technique is described as nasal high flow and can be used in infants and children at risk of apnea during anesthesia. AIM: We investigated the use of nasal high flow oxygen delivery during anesthesia in children with abnormal airways requiring tubeless airway assessment or surgery. METHODS: Data and outcomes of pediatric patients receiving nasal high flow for upper airway procedures were analyzed. Four categories were defined: (i) tubeless airway surgery, (ii) flexible bronchoscopy, (iii) expected difficult airway, and (iv) comorbidity related risk of apnea. Anesthesia was induced intravenously or with sevoflurane (4-8%) and then converted to total intravenous anesthesia aiming for spontaneous ventilation. Age appropriate nasal high flow cannulae were secured with 100% oxygen delivery at weight-related flow rates. Topicalization of the airway was achieved with lignocaine. Complication rates of desaturation requiring interruption of procedure for rescue oxygenation were recorded. RESULTS: Twenty children were analyzed with age range of 5 days to 11 years, ASA 1-4, and weight range 3-57 kg. Fifteen were induced with sevoflurane and 100% oxygen, five received total intravenous anesthesia only. All children received Optiflow™ nasal high flow and intravenous anesthesia during their procedure. Average SpO2 recorded was 96% with lowest SpO2 77%. One required rescue oxygenation. Median length of procedure was 32 min, (range 3-61). Most common indication was tubeless airway surgery but seven children had more than one indication. CONCLUSION: Nasal high flow can be used in spontaneously breathing children with abnormal airways for maintenance of oxygenation during anesthesia for tubeless airway procedures.

Neurophysiological correlates of sevoflurane-induced unconsciousness.

BACKGROUND: Recent studies of anesthetic-induced unconsciousness in humans have focused predominantly on the intravenous drug propofol and have identified anterior dominance of alpha rhythms and frontal phase-amplitude coupling patterns as neurophysiological markers. However, it is unclear whether the correlates of propofol-induced unconsciousness are generalizable to inhaled anesthetics, which have distinct molecular targets and which are used more commonly in clinical practice. METHODS: The authors recorded 64-channel electroencephalograms in healthy human participants during consciousness, sevoflurane-induced unconsciousness, and recovery (n = 10; n = 7 suitable for analysis). Spectrograms and scalp distributions of low-frequency (1 Hz) and alpha (10 Hz) power were analyzed, and phase-amplitude modulation between these two frequencies was calculated in frontal and parietal regions. Phase lag index was used to assess phase relationships across the cortex. RESULTS: At concentrations sufficient for unconsciousness, sevoflurane did not result in a consistent anteriorization of alpha power; the relationship between low-frequency phase and alpha amplitude in the frontal cortex did not undergo characteristic transitions. By contrast, there was significant cross-frequency coupling in the parietal region during consciousness that was not observed after loss of consciousness. Furthermore, a reversible disruption of anterior-posterior phase relationships in the alpha bandwidth was identified as a correlate of sevoflurane-induced unconsciousness. CONCLUSION: In humans, sevoflurane-induced unconsciousness is not correlated with anteriorization of alpha and related cross-frequency patterns, but rather by a disruption of phase-amplitude coupling in the parietal region and phase-phase relationships across the cortex.

Analysis of histomorphology in malignant hyperthermia-susceptible patients.

BACKGROUND: Malignant hyperthermia (MH) is a potentially lethal disorder of skeletal muscle triggered by anesthetic agents. A histomorphological examination of diseased muscle may provide insight into MH pathophysiology, but it is not a routine part of standard-of-care practice for the identification of MH-susceptibility. In this study, we investigated muscle histomorphology in a large cohort of MH-susceptible (MHS) patients and examined its relationship to genotype and phenotype. METHODS: All consenting patients who were identified as MHS based on a caffeine-halothane contracture test (CHCT) performed during 1992-2011 were retrospectively identified and recruited for this study. Results of the histomorphological examination, which is a routine part of our centre-specific practice, were reviewed. Patient demographics, MH proband status, histological features, CHCTs, and genetic results for MH-causative mutations were summarized. RESULTS: Seven of the 399 patients classified as MHS had histological characteristics consistent with central core disease, and one patient was a carrier of Duchenne's muscular dystrophy. Eighty-six (22%) patients had histological abnormalities, and five (6%) of these had evidence of "frank" myopathy. No histologic abnormalities were consistent among the MHS patients; however, a higher proportion of MH probands had abnormal histomorphology compared with the general MHS population, and patients with evidence of "frank" myopathy showed similarities in clinical history, biochemistry, CHCT, and genetic testing. CONCLUSION: Despite the inability of the histomorphological examination to identify consistent features in MHS patients, histology may serve as a potential adjunct to CHCT and aid in the identification of other myopathies. Nevertheless, the specifics of its utility ought to be assessed in other studies and by way of formal cost-effectiveness analysis.

eLearning among Canadian anesthesia residents: a survey of podcast use and content needs.

BACKGROUND: Podcasts are increasingly being used in medical education. In this study, we conducted a survey of Canadian anesthesia residents to better delineate the content needs, format preferences, and usage patterns among anesthesia residents. METHODS: 10/16 Canadian anesthesia program directors, representing 443/659 Canadian anesthesia residents, allowed their residents to be included in the study. 169/659 (24%) residents responded to our survey. A 17-item survey tool developed by the investigators was distributed by email eliciting information on patterns of podcast use, preferred content, preferred format, and podcast adjuncts perceived to increase knowledge retention. RESULTS: 60% (91/151) had used medical podcasts with 67% of these users spending up to 1 hour per week on podcasts. 72.3% of respondents selected 'ability to review materials whenever I want' was selected by the majority of respondents (72%) as the reason they found podcasts to be valuable. No clear preference was shown for audio, video, or slidecast podcasts. Physiology (88%) and pharmacology (87%) were the most requested basic science topics while regional anesthesia (84%), intensive care (79%) and crisis resource management (86%) were the most requested for procedural, clinical and professional topics respectively. Respondents stated they would most likely view podcasts that contained procedural skills, journal article summaries and case presentations and that were between 5-15 minutes in duration A significantly greater proportion of senior residents (81%) requested podcasts on 'pediatric anesthesia' compared to junior residents 57% (P = 0.007). CONCLUSIONS: The majority of respondents are using podcasts. Anesthesia residents have preferred podcast content, types, length and format that educators should be cognizant of when developing and providing podcasts.

Opioids for acute pain management in children.

Opioids are integral to multimodal analgesic regimens in children with moderate to severe acute pain. Throughout normal childhood there are marked changes in physiology, and social and psychological development that influence the perception and expression of pain, the pharmacology of opioids, and how they are used. A multidimensional pain assessment is key to guiding appropriate opioid prescribing. Most of the commonly used opioids in adults are used in children, with the increasing exception of codeine (as a result of regulatory change), and are generally well tolerated. Patient groups at increased risk of ventilatory impairment include neonates and those with obstructive sleep apnoea, severe neurodevelopmental conditions, trisomy 21, and severe epilepsy. Slow-release opioids are not recommended for general use, but may be used in select populations, for example, following scoliosis surgery, major trauma or burns. Prescribing and administration errors are a major issue in paediatrics generally; the potential consequences of opioid prescribing or administration errors are serious, particularly following hospital discharge. Opioids prescribed at discharge are frequently in excess of a child's analgesic requirements; three to five days supply appears sufficient for the majority of common paediatric operations. Discharge opioid prescriptions have been linked to long-term opioid use in adolescents with risk factors. Misuse of prescription opioids by adolescents is also concerning, with prevalence estimates ranging from 1.1% to 20%. Caregivers have a tendency to underdose opioids in their children; caregiver education may improve appropriate administration. Caregivers must also be provided with instructions on safe storage and disposal of unused opioids.