Background
Previously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group’s mandate for this article was to arrive at updated practice recommendations for management of the unconscious/induced patient in whom difficult or failed tracheal intubation is encountered.

/pdf/the-difficult-airway-with-recommendations-for-management-4pqudp82av.pdf

The difficult airway with recommendations for management ??? Part 1 ??? Difficult tracheal intubation encountered in an unconscious/induced patient

Propofol is an intravenous agent used commonly for the induction and maintenance of anesthesia, procedural, and critical care sedation in children. The mechanisms of action on the central nervous system involve interactions at various neurotransmitter receptors, especially the gamma-aminobutyric acid A receptor. Approved for use in the USA by the Food and Drug Administration in 1989, its use for induction of anesthesia in children less than 3 years of age still remains off-label. Despite its wide use in pediatric anesthesia, there is conflicting literature about its safety and serious adverse effects in particular subsets of children. Particularly as children are not “little adults”, in this review, we emphasize
 the maturational aspects of propofol pharmacokinetics. Despite the myriad of propofol pharmacokinetic-pharmacodynamic studies and the ability to use allometrical scaling to smooth out differences due to size and age, there is no optimal model that can be used in target controlled infusion pumps for providing closed loop total intravenous anesthesia in children. As the commercial formulation of propofol is a nutrient-rich emulsion, the risk for bacterial contamination exists despite the Food and Drug Administration mandating addition of antimicrobial preservative, calling for manufacturers’ directions to discard open vials after 6 h. While propofol has advantages over inhalation anesthesia such as less postoperative nausea and emergence delirium in children, pain on injection remains a problem even with newer formulations. Propofol is known to depress mitochondrial function by its action as an uncoupling agent in oxidative phosphorylation. This has implications for children with mitochondrial diseases and the occurrence of propofol-related infusion syndrome, a rare but seriously life-threatening complication of propofol. At the time of this review, there is no direct evidence in humans for propofol-induced neurotoxicity to the infant brain; however, current concerns of neuroapoptosis in developing brains induced by propofol persist and continue to be a focus of research.

/pdf/propofol-a-review-of-its-role-in-pediatric-anesthesia-and-aq44w29sq4.pdf

Propofol: a review of its role in pediatric anesthesia and sedation

Background Previously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group’s mandate for this article was to arrive at updated practice recommendations for management of the unconscious/ induced patient in whom difficult or failed tracheal intubation is encountered. Methods Nineteen clinicians with backgrounds in anesthesia, emergency medicine, and intensive care joined this iteration of the CAFG. Each member was assigned topics and conducted reviews of Medline, EMBASE, and Cochrane databases. Results were presented and discussed during multiple teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made together with assigned levels of evidence modelled after previously published criteria. Conclusions The clinician must be aware of the potential for harm to the patient that can occur with multiple attempts at tracheal intubation. This likelihood can be minimized by moving early from an unsuccessful primary intubation technique to an alternative ‘‘Plan B’’ technique if oxygenation by face mask or ventilation using a supraglottic device is non-problematic. Irrespective of the technique(s) used, failure to achieve successful tracheal intubation in a maximum of three attempts defines failed tracheal intubation and signals the need to engage an exit strategy. Failure to oxygenate by face mask or supraglottic device ventilation occurring in conjunction with failed tracheal intubation defines a failed oxygenation, ‘‘cannot intubate, cannot oxygenate’’ situation. Cricothyrotomy must then be undertaken without delay, although if not already tried, an expedited and concurrent attempt can be made to place a supraglottic device.

/pdf/the-difficult-airway-with-recommendations-for-management-37y8hu1svi.pdf

The difficult airway with recommendations for management - Part 1 - Difficult tracheal intubation encountered in an unconscious/induced patient Prise en charge des voies aeriennes - 1re partie - Recommandations lorsque des difficultes sont constatees chez le patient inconscient/anesthesie ´

Administration of anesthetic agents fundamentally shifts the responsibility for maintenance of homeostasis from the patient and their intrinsic physiological regulatory mechanisms to the anesthesiologist Continuous delivery of oxygen and nutrients to the brain is necessary to prevent irreversible injury and arises from a complex series of regulatory mechanisms that ensure uninterrupted cerebral blood flow Our understanding of these regulatory mechanisms and the effects of anesthetics on them has been driven by the tireless work of pioneers in the field It is of paramount importance that the anesthesiologist shares this understanding Herein, we will review the physiological determinants of cerebral blood flow and how delivery of anesthesia impacts these processes

https://journals.sagepub.com/doi/pdf/10.1177/0271678X18789273

Effects of anesthesia on cerebral blood flow, metabolism, and neuroprotection:

Summary
Background

We reviewed the updated literature and performed a meta-analysis based on randomized controlled trials in children to compare the clinical efficacy between video laryngoscopes (VLs) and direct laryngoscopes (DLs).



Methods

We searched articles published in English matching the key words ‘video laryngoscope (including Airtraq, GlideScope, Storz, TruView, AWS, Bullard, McGrath)’ AND ‘direct laryngoscope’ AND ‘children (including pediatric, infant, neonate)’ in PubMed, Ovid, Google Scholar, and the Cochrane Library databases. Only prospective randomized controlled trials (RCTs), which compared the use of VLs and DLs in children, were included. The relative risk (RR), weighted mean difference (WMD), and their corresponding 95% confidence interval (95% CI) were calculated using the quality effects model of the metaxl 1.3 software for outcome data.



Results

Fourteen studies were included in this meta-analysis. Although VLs improved the glottis visualization in most children either with normal airways or with potentially difficult intubations, the time to intubation (TTI) was prolonged in comparison to DLs (WMD: 4.9 s; 95% CI: 2.6–7.1). Subgroup analysis showed the GlideScope (WMD: 5.2 s; 95% CI: 2.0–8.5), TruView (WMD: 5.1 s; 95% CI: 0.7–9.5), Storz (WMD: 6.4 s; 95% CI: 4.8–8.1), and Bullard (WMD: 37.5 s; 95% CI: 21.0–54.0) rather than Airtraq (WMD: 0.6 s; 95% CI: −7.7–8.9) prolonged TTI. Although the success rate of the first attempt (RR: 0.96; 95% CI: 0.92–1.00) and associated complications (RR: 1.11; 95% CI: 0.39–3.16) were similar in both groups, VLs were associated with a higher incidence of failure (RR: 6.70; 95% CI: 1.53–29.39).



Conclusion

This meta-analysis demonstrates that although VLs improved glottis visualization in pediatric patients, this was at the expense of prolonged TTI and increased failures. However, further studies are needed to clarify the efficacy and safety of VLs in hands of nonexperts and in children with airway problems.

Pediatric video laryngoscope versus direct laryngoscope: a meta-analysis of randomized controlled trials.

Pediatric patients present in varying stages of development, from the premature neonate to full-grown teenager. Appreciation of the unique physiologic states associated with the different stages of development will direct anesthetic management. Preoperative evaluation of the small child should include the neonatal history as this may indicate comorbid pulmonary and cardiac disease and linked syndromes which must be investigated. Lung isolation is not always necessary in pediatric thoracic surgery. Appropriate lung isolation techniques will depend on the age and size of the patient as there is no single technique that is suitable for all pediatric patients. Physiologic manifestation of one-lung ventilation may be more pronounced in children than in adults. The compliant rib cage, compressible lung parenchyma, reduced FRC under anesthesia and higher oxygen consumption in the child contribute to aggravate hypoxemia during lung isolation. Adult thoracic surgery is often related to tumor excision whereas pediatric thoracic disease encompasses a greater variety of pathology. Each specific disease state has its own particular anesthetic considerations and management ­strategy. Pain management in the pediatric population has evolved to include a greater use of regional and neuraxial techniques, even in the smallest of infants. Postoperative disposition will depend on the type and length of surgery, extent of resection or manipulation, and nature of the underlying condition. Many pediatric patients will require postoperative ventilation or close cardiorespiratory monitoring following the procedure.

Anesthesia for Pediatric Thoracic Surgery

BACKGROUND The glutamate-nitric oxide-cyclic guanosine 3',5'-monophosphate (cGMP) pathway is potentially an effective target for general anesthetics. Plasma cGMP concentrations are reduced after an increase in predicted plasma propofol concentrations during sedation in healthy adult volunteers. We hypothesized that an increase in measured plasma propofol concentration leads to a reduction in plasma cGMP in anesthetized children. METHODS Eighteen healthy children aged 46.8 (+/-19.6) mo, requiring general anesthesia for lower body surgical procedures were enrolled. After inhaled induction, tracheal intubation and initiation of intermittent positive pressure ventilation, caudal epidural analgesia was performed. Anesthesia was maintained using a continuous propofol infusion adapted from a previously published regimen to achieve predicted propofol plasma concentration of 6, 3, and 1.5 microg/mL after 30, 50, and 70 min, respectively. Samples for propofol and cGMP plasma concentrations were collected and analyzed using high-performance liquid chromatography and an enzyme immunoassay system. RESULTS The plasma cGMP concentrations varied significantly (median [range]) 19.2 [11.8-23.5], 21.3 [14.6-30.8], and 24.9 [15.7-37.8] nmol/L among each predicted plasma propofol concentration, P < 0.0001. The correlation coefficient (r) was -0.62. CONCLUSIONS This study demonstrates that an increase in plasma propofol concentration leads to a decrease in plasma cGMP in healthy children, and could serve as a biochemical marker for depth of propofol anesthesia in children.

The effect of varying continuous propofol infusions on plasma cyclic guanosine 3',5'-monophosphate concentrations in anesthetized children.

To the Editor, Retrospective series tend to report a lower incidence of difficult intubation in pediatric patients than in adults. It is also believed that the incidence of unanticipated difficult intubation in children is exceedingly low. We conducted a retrospective review in a pediatric tertiary care facility to identify the incidence and clinical characteristics of patients with difficult airways undergoing surgery. With research ethics board approval (December 2011), we analyzed the anesthesia records of all patients \\ 18 yr presenting for surgery at The Hospital for Sick Children over a two-year period (January 1, 2010 to December 31, 2011). Patients with a difficult airway were defined as (1) those having a Cormack-Lehane grade 3 or worse view on direct laryngoscopy (which was routinely documented in the anesthesia record) or (2) those who were identified preoperatively as potentially having a difficult airway or who had been previously demonstrated to have one and were subsequently managed by pre-planned videolaryngoscopic or flexible bronchoscopic intubation. All cases were assessed and managed by an attending pediatric anesthesiologist. The patients’ charts were reviewed for demographics, preoperative airway history/characteristics, and airway management details. Descriptive statistics were used to analyze the data. Of the 22,766 cases of anesthetics delivered during the study period, 125 (0.5%) were deemed to have a difficult intubation. Among them, 21 (16%) were emergency procedures, 13 of which were primary airway emergencies. Also, 73 (58%) of the patients were diagnosed to have a syndrome known to be associated with difficult intubation. In descending order of prevalence, the following accounted for 48 (66%) of these cases: Goldenhar, Pierre-Robin, arthrogryposis, Apert, Treacher-Collins, and various mucopolysaccharidoses. Of the 125 difficult airway patients, 70 (56%) had undergone general anesthesia prior to the study period. Only 32 (46%) of the 70 patients had a history of prior difficult airway. In all, 100 (80%) of the 125 cases had an anticipated difficult airway based on their history and airway physical examination. Airway management in the remaining 25 (20%) patients in whom a difficult airway had been unanticipated is shown in the Figure. The vast majority (91.2%) of the difficult airway cases were managed with endotracheal intubation. Another 5.6% were managed with a supraglottic airway and the remaining 3.2% with nasal prongs or face mask. There were no deaths attributable to airway management in this series. A particularly interesting finding in this study was that one in five difficult airways was unanticipated despite the fact that an attending anesthesiologist was involved in each case and the study took place in a pediatric tertiary care center. This is in contrast to the popular belief that the vast majority of pediatric difficult airway cases are predictable. We also found that, among the difficult airway patients in our study who had had a previous anesthetic, more than half did not have a history of airway difficulty. This finding speaks against a commonly held adage that tracheal intubation usually becomes less difficult as the child develops. Indeed, in conditions such as Goldenhar syndrome, arthrogryposis, and the mucopolysaccharidoses, C. Karsli, MD (&) C. Pehora, MN A. Al-Izzi, MD P. Mathew, MD Department of Anesthesiology and Pain Medicine, The Hospital for Sick Children, Toronto, ON, Canada e-mail: Cengiz.karsli@sickkids.ca

/pdf/a-retrospective-review-of-pediatric-difficult-airways-once-4unq192lg0.pdf

Cengiz Karsli

Papers

Anesthesia for Pediatric Thoracic Surgery

The effect of varying continuous propofol infusions on plasma cyclic guanosine 3',5'-monophosphate concentrations in anesthetized children.

A retrospective review of pediatric difficult airways: once easy, not always easy.

Anesthesia for Genetic, Metabolic, & Dysmorphic Syndromes of Childhood. 2nd ed.

The Effect of Nitrous Oxide on Cerebral Blood Flow Velocity in Children Anesthetized with Propofol: [2002][A-1258]