Mainstem Bronchial Diameters and Dimensions in Infants and Children: A Systematic Review of the Literature.

Anatomic measurements of the right (RMB) and left mainstem bronchi (LMB) in infants and children have been accomplished using various modalities. The objective of the present review was to determine whether enough data were available to provide standardized lower airway dimensions in the pediatric population. For the present study, 12 studies with data of the lower pediatric airway dimensions of 1,611 children published from 1923-2020 were reviewed and analyzed. The eligible criteria included studies measuring lower airway dimensions in the pediatric population. Various techniques were used for airway measurement, with computed tomography studies being most abundant. There was a progressive increase in the size of RMB and LMB with age, with a close approximation of the LMB-to-RMB ratio across all studies. In children younger than 1 year old, the RMB and LMB diameters were between 4 and 5 mm and 3 and 5 mm, respectively. Overall, there was significant variation in the methods and modality used to obtain measurements, and therefore it was difficult to establish standardized lower airway dimensions in the pediatric population. Additional homogeneous data with standardized measurement techniques and modalities across different pediatric age groups are needed to define these dimensions further. Such data may be helpful in designing airway equipment, lung isolation devices, and airway stents.

Distinct, sex-dependent miRNA signatures in piglet hippocampus induced by a clinically relevant isoflurane exposure: a pilot study.

PURPOSE: To evaluate the effects of sex on miRNA expression in the hippocampus after isoflurane anesthesia in a neonatal piglet model. METHODS: Six male and 6 female piglets, aged 3-5 days, were anesthetized with 2% isoflurane in room air for 3 h. Full physiologic monitoring was observed. Untreated animals (6 male, 6 female) served as controls. Expression of miRNAs in hippocampus was assessed. RESULTS: In controls, miRNA expression in the hippocampus was highly conserved between males and females. However, 17/326 displayed sex-dependent differences: 10 miRNAs were more highly expressed in males; 7 showed lower expression in males than females. Isoflurane was associated with changes in the expression of distinct subsets of miRNAs in both males and females. In females, 14/326 miRNAs were significantly changed (3 downregulated; 11 upregulated); in males, 17/326 miRNAs were changed (7 downregulated; 10 upregulated). There was no overlap in significantly changed miRNAs between isoflurane-exposed males and females. CONCLUSIONS: In the neonatal piglet hippocampus, miRNA expression was highly conserved. There was no overlap in miRNA expression between isoflurane-exposed males and females, suggesting sex differences in isoflurane-induced miRNA expression. These results support the hypothesis that a clinically relevant exposure to isoflurane induces distinct miRNA signatures in the hippocampus of neonatal male and female piglets. Their functional relevance in anesthesia-induced neurotoxicity remains unknown, although changes in specific miRNAs may either contribute to or protect against anesthesia-induced neurotoxicity.

Effects of partial sleep deprivation on reaction time in anesthesiologists.

BACKGROUND: Fatigue in anesthesiologists may have implications that extend beyond individual well-being. AIM: The aim of the present study was to evaluate the impact of sleep deprivation on the reaction time in anesthesiologists either after an overnight call or regular working hours. Moderation of this effect by coping strategies was observed. METHODS: Psychomotor vigilance test was used to assess reaction time in 23 anesthesiologists at two time-points: (i) on a regular non-call day and (ii) after a 17-h in-house call. Student's paired t-test was used to compare Psychomotor Vigilance Task data at these two moments. Change score regression was performed to determine the association between coping strategies, assessed using the Coping Strategy Indicator instrument, and decline in reaction time after night call. RESULTS: Twenty-one colleagues completed the psychomotor vigilance test measurements after two decided to end their participation for personal reasons. Post-call psychomotor vigilance test mean reaction time decreased by an average of 31.2 ms (95% CI: 0.5, 61.9; P = 0.047) when compared to regular day. Reliance on specific coping mechanisms, indicated by Coping Strategy Indicator scale scores, included problem-solving (28 ± 4), followed by seeking social support (23 ± 5) and avoidance (19 ± 4). The change score regression model (r2 = 0.48) found that greater reliance on avoidance was associated with greater increase in reaction time after night call. CONCLUSION: Reaction time increased considerably in anesthesiologists after a night call duty. Greater subjective reliance on avoidance as a coping strategy was associated with greater deterioration in performance.

Selective induction of IL-1ß after a brief isoflurane anesthetic in children undergoing MRI examination.

PURPOSE: To determine if isoflurane anesthesia without surgery causes systemic inflammation in children. Inflammation is targeted as responsible for the development of many neurologic pathologies. The effect will be evaluated by measuring serum cytokine levels before and after isoflurane anesthesia. The possible neurotoxic effect of anesthetic agents is a concern in pediatric anesthesia. Questions remain as to the true effects of anesthesia alone on systemic inflammation. The current study assesses systemic inflammatory response to general anesthesia in children not exposed to surgical stress. METHODS: Twenty-five patients, aged 6 months to 11 years undergoing MRI scanning were recruited. Patients with ASA Physical Status Classification >II, known neurologic disease, prematurity, recent infection, or current treatment with anti-inflammatory medications were excluded. Each patient received a sevoflurane induction, peripheral intravenous catheterization, and laryngeal mask airway placement. Isoflurane was titrated to ensure adequate depth of anesthesia. Two peripheral blood samples were obtained: one immediately after placement of the PIV and one upon arrival to the post-anesthesia care unit. Serum cytokine levels were compared between pre- and post-isoflurane time points using paired t tests. RESULTS: For all patients, interleukin-1ß increased after isoflurane when compared to pre-isoflurane samples (pre = 25.97 ± 9.01, post = 38.53 ± 16.56, p = 0.0002). Serum levels of IL-6 (pre = 2.28 ± 2.27, post = 2.04 ± 2.15, p = 0.146) and tumor necrosis factor-α (pre = 94.26 ± 18.07, post = 85.84 ± 12.12, p = 0.057) were not significantly changed. Interleukin-10 and vascular endothelial growth factor were undetectable in pre- and post-isoflurane samples at a minimum detection threshold of 6.6 and 10 pg/ml, respectively. CONCLUSIONS: A brief (approximately 60 min) exposure to isoflurane general anesthesia, without induced surgical stress, significantly increased serum IL-1ß, a selective activation marker of systemic inflammation (IL-1ß pathway).

Time to talk about work-hour impact on anesthesiologists: The effects of sleep deprivation on Profile of Mood States and cognitive tasks.

BACKGROUND: A physician's fatigue raises significant concerns regarding personal and patient safety. Effects of sleep deprivation on clinical performance and the quality of patient care are major considerations of today's health care environment. AIM: To evaluate the impact of partial sleep deprivation after a 17-h overnight call (3 pm-7 am) on the mood status and cognitive skills of anesthesiologists in an academic clinical hospital setting, as compared to these parameters during regular working hours. METHODS: Taking circadian rhythm into account, the following measures were assessed in 21 pediatric anesthesiologists at two time points over the course of the study; (i) between 7 and 8 am on a regular non call day, and (ii) between 7 and 8 am after a 17-h in-house call (3 pm-7 am). Six mood states were assessed using the Profile of Mood States. A Total Mood Disturbance (TMD) score was obtained as the sum of all mood scores minus vigor. The total score provides a global estimate of affective state. Simple cognitive tests were similarly administered to assess cognitive skills. A two-tailed paired t-test was used to compare data between regular and post call days. A P < 0.05 was used. RESULTS: The study cohort included 21 pediatric anesthesiologists at a tertiary care children's hospital. Tension, anger, fatigue, confusion, TMD, irritability, feeling jittery, and sleepiness were significantly affected (P < 0.05). A decrease in vigor, energy, and confidence was observed after a night call shift (P < 0.05). There was also a decrease in being "talkative" after the call shift (P < 0.05). CONCLUSION: Partial sleep deprivation affects the total mood status of anesthesiologists and impacts their cognitive skills. These findings are particularly relevant in a context of increased work expectation, particularly on clinical performance in our modern medical system. Such observations suggest that there may be changes that impact the safety of our patients and the quality of health care that is provided.

Brain temperature: heat production, elimination and clinical relevance.

Neurological insults are a leading cause of morbidity and mortality, both in adults and especially in children. Among possible therapeutic strategies to limit clinical cerebral damage and improve outcomes, hypothermia remains a promising and beneficial approach. However, its advantages are still debated after decades of use. Studies in adults have generated conflicting results, whereas in children recent data even suggest that hypothermia may be detrimental. Is it because brain temperature physiology is not well understood and/or not applied properly, that hypothermia fails to convince clinicians of its potential benefits? Or is it because hypothermia is not, as believed, the optimal strategy to improve outcome in patients affected with an acute neurological insult? This review article should help to explain the fundamental physiological principles of brain heat production, distribution and elimination under normal conditions and discuss why hypothermia cannot yet be recommended routinely in the management of children affected with various neurological insults.

Effects of hemodilution after traumatic brain injury in juvenile rats.

BACKGROUND: Normovolemic hemodilution (HD) in adult animal studies has shown exacerbation of traumatic brain injury (TBI) lesion volumes. Similar studies in juvenile rats have not been reported and outcomes are likely to be different. This study investigated the effects of normovolemic hemodilution (21% hematocrit) in a juvenile TBI (jTBI) model. METHODS: Twenty 17-day-old rats underwent moderate cortical contusion impact injury (CCI) and were divided into four groups: CCI/hemodilution (HD) (group HD), CCI/no HD (group C), Sham/HD (group SHD), and Sham/no HD (group S). Regional laser Doppler flowmetry (LDF), edema formation (MRI-T2WI), water mobility assessed using diffusion weighted imaging (MRI-DWI), open field activity tests, and histological analyses were evaluated for lesion characteristics. RESULTS: Hemodilution significantly increased blood flow in the HD compared to the C group after TBI. T2WI revealed a significantly increased extravascular blood volume in HD at 1, 7, and 14 days post-CCI. Edematous tissue and total contusional lesion volume were higher in HD-treated animals at 1 and 14 days. DWI revealed that HD, SHD, and C groups had elevated water mobility compared to S groups in the ipsilateral cortex and striatum. Histology showed a larger cortical lesion in the C than HD group. Open field activity was increased in HD, C, and SHD groups compared to the S group. CONCLUSIONS: Hemodilution results in significant brain hyperemia with increased edema formation, extravascular blood volume, and water mobility after jTBI. Hemodilution results in less cortical damage but did not alter behavior. Hemodilution is likely not to be clinically beneficial following jTBI.

Fundamentals of neuronal apoptosis relevant to pediatric anesthesia.

The programmed cell death or apoptosis is a complex biochemical process that has risen to prominence in pediatric anesthesia. Preclinical studies report a dose-dependent neuronal apoptosis during synaptogenesis following exposure to intravenous and volatile anesthetic agents. Although emerging clinical data do not universally indicate an increased neurodegenerative risk of general anesthesia in early human life, a great deal of uncertainty was created within the pediatric anesthesia community. This was at least partially caused by the demand of understanding of basic science concepts and knowledge of apoptosis frequently out of reach to the clinician. It is, however, important for the pediatric anesthesiologist to be familiar with the basic science concepts of neuronal apoptosis to be able to critically evaluate current and future preclinical data in this area and future clinical studies. This current review describes the extrinsic and intrinsic pathways involved in the cell death process and discusses techniques commonly employed to determine apoptosis. In addition, potential mechanisms of anesthesia-induced neuronal apoptosis are illustrated in this review.

Airway management in children: ultrasonography assessment of tracheal intubation in real time?

BACKGROUND: Pediatric tracheal intubation requires considerable expertise and can represent a challenge to many anesthesiologists. Confirmation of correct tracheal tube position relies on direct visualization or indirect measures, such as auscultation and capnography. These methods have varying sensitivity and specificity, especially in the infant and young child. Ultrasonography is noninvasive and is becoming more readily available to the anesthesiologist. In this study, we investigated the characteristic real-time ultrasonographic findings of the normal pediatric airway during tracheal intubation and its suitability for clinical use. METHODS: Thirty healthy children with normal airways requiring tracheal intubation were studied. Ultrasonographic measurements of the pediatric airway during tracheal intubation under deep inhaled anesthesia were performed using a Sonosite Titan (Sonosite, Bothell, WA) scanner while recording characteristic images during this process. Correct tracheal tube placement was further confirmed using auscultation and satisfactory end-tidal capnography. RESULTS: The mean (+/- sd) age of studied patients was 48 +/- 37 mo, weight was 19.7. +/- 8.6 kg and the sex ratio (m/f) was 1:2. Successful tracheal intubation was verified using the following criteria: 1) identification of the trachea and tracheal rings, 2) visualization of vocal cords, 3) widening of glottis as the tracheal tube passes through, and 4) tracheal tube position above carina and demonstration of movement of the chest wall visceroparietal pleural interface (i.e., sliding sign) after manual ventilation of the lungs. One esophageal intubation was readily recognized by visualization of the tube in the left paratracheal space. CONCLUSION: This study describes characteristic ultrasonographic findings of the pediatric airway during tracheal intubation. It suggests that ultrasonography may be useful for airway management in children.

The use of NSAIDs in pediatric scoliosis surgery - a survey of physicians' prescribing practice.

BACKGROUND: Pediatric scoliosis surgery is associated with considerable postoperative pain requiring opioids for analgesia. Nonsteroidal antiinflammatory drugs (NSAIDs) can be used as adjuvants for analgesia; however, the potential of these agents to affect bone healing raises concerns. No large-scale prospective studies have been performed to evaluate the benefit-to-risk ratio of NSAID use after pediatric scoliosis surgery. Given the lack of evidence in the literature, a survey of practice patterns of anesthesiologists from around the world was conducted with respect to the use of NSAIDs after pediatric spinal fusion surgery for scoliosis. METHODS: One hundred and fourteen anesthesiologists from international academic pediatric hospitals were asked to complete an online survey. After 1 month, nonresponders were sent a second e-mail asking for their participation. All questions were developed specifically for this study. RESULTS: Out of 80 anesthesiologists who responded 61 were included in the final analysis. Fifty-nine percent routinely use NSAIDs, the most common agents being intravenous ketorolac and oral ibuprofen. The majority of respondents begin to administer NSAIDs within the first three postoperative days for a duration of four or more days. The primary reason for not routinely prescribing NSAIDs was the risk of bone nonunion. CONCLUSIONS: This survey demonstrates that the practice patterns of pediatric anesthesiologists from around the world with respect to the administration of NSAIDs for the management of postoperative pain after pediatric spinal fusion reflects the conflicting evidence in the literature and the lack of high-quality studies in humans.

Impact of anesthetic agents on cerebrovascular physiology in children.

The role of the pediatric neuroanesthetist is to provide comprehensive care to children with neurologic pathologies. The cerebral physiology is influenced by the developmental stage of the child. The understanding of the effects of anesthetic agents on the physiology of cerebral vasculature in the pediatric population has significantly increased in the past decade allowing a more rationale decision making in anesthesia management. Although no single anesthetic technique can be recommended, sound knowledge of the principles of cerebral physiology and anesthetic neuropharmacology will facilitate the care of pediatric neurosurgical patients.

The pediatric airway: Historical concepts, new findings, and what matters.

New observations from novel imaging techniques regarding the anatomy, dimensions, and shape of the pediatric airway have emerged and provide insight for potential changes in the clinical management of the airway in infants and children. These new findings are challenging the historical concepts of a funnel-shaped upper airway with the cricoid ring as the narrowest dimension. Although these tenets have been accepted and used to guide clinical practice in airway management, there are limited clinical investigations in children to support the validity of these concepts. Imaging modalities such as magnetic resonance imaging, computed tomography (CT) scanning, multi-detector CT imaging, and videobronchoscopy suggest the need to revisit the historical view of the pediatric airway. This manuscript reviews the historical evolution of pediatric airway studies, summarizes important scientific observations from recent investigations relevant to our clinical understanding of pediatric airway anatomy, and discusses the importance of these findings for pediatric airway management.

Anatomic relationship between the internal jugular vein and the carotid artery in preschool children--an ultrasonographic study.

BACKGROUND: Central venous cannulation in young children is technically difficult and may lead to potentially serious complications especially when performed blindly or using anatomical landmarks only. AIM: The aim of this study was to determine the anatomical relationship of the internal jugular vein (IJV) and the common carotid artery (CA) in preschool children using ultrasound. METHODS: Forty five children aged 60 months and under were included prospectively and divided into three groups: group 1: <6 months, group 2: 7-18 months and group 3: 19-60 months. With the head in neutral position the location of the left and right IJV was noted as anterior (A), anterolateral (AL), lateral (L) or medial (M) in relation to the CA at the level of the cricoid cartilage. Depths of IJV and CA as well as time taken to locate the vessels were recorded. RESULTS: The IJV was more commonly found in the AL position in all groups. The mean depth was 0.96 cm in group 1, 0.95 cm in group 2 and 3. Mean duration for localization of the vessels was 4.2 s in group 1, 4 s in group 2 and 4.3 s in group 3. The differences between the groups were not significant. CONCLUSION: This study demonstrates that the IJV cover the CA in the majority of young children. Depth of the IJV is rarely more than 1 cm deep to the skin. Ultrasound location of the IJV and CA is easy and does not necessarily delay the procedure. The findings of this study support the use of ultrasound guidance for CVC in children.

THIS ARTICLE HAS BEEN RETRACTED Anatomic relationship between the internal jugular vein and the carotid artery in pre-school children--an ultrasonographic study.

BACKGROUND: Central venous cannulation (CVC) in young children is technically difficult and may lead to potentially serious complications especially when performed blindly or using anatomical landmarks only. The aim of this study was to determine the anatomical relationship of the internal jugular vein (IJV) and the common carotid artery (CA) in preschool children using ultrasound. METHODS: Forty-five children aged 60 months and under were included prospectively and divided into three groups: Group 1: <6 months, Group 2: 7-18 months and Group 3: 19-60 months. With the head in neutral position the location of the left and right IJV was noted as anterior, anterolateral (AL), lateral or medial in relation to the CA at the level of the cricoid cartilage. Depths of IJV and CA as well as time taken to locate the vessels were recorded. RESULTS: The IJV was more commonly found in the AL position in all groups. The mean depth was 0.96 cm in Group 1, 0.95 cm in Group 2 and 3. Mean duration for localization of the vessels was 4.2 s in Group 1, 4 s in Group 2 and 4.3 s in Group 3. The differences between the groups were not significant. CONCLUSION: This study demonstrates that the IJV cover the CA in the majority of young children. Depth of the IJV is rarely more than 1 cm deep to the skin. Ultrasound location of the IJV and CA is easy and does not necessarily delay the procedure. The findings of this study support the use of ultrasound guidance for CVC in children.

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

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.

Therapeutic hypothermia.

Therapeutic hypothermia, introduced more than 5 decades ago, remains an important neuroprotective factor in the surgery for the correction of congenital heart disease, in particular when intraoperative circulatory arrest is required. Hypothermia decreases cerebral metabolism and energy consumption and reduces the extent of degenerative processes such as the excitotoxic cascade, apoptotic and necrotic cell death, microglial activation, oxidative stress, and inflammation. Neurological outcome has become the focus of several studies in the recent years, and deep hypothermic circulatory arrest durations of more than 40 minutes are associated with increased mid- and long-term disability. Physiologic cerebral flow-metabolism coupling seems to be preserved with moderate and mild hypothermia, but cerebral blood flow autoregulation is probably altered after deep hypothermic circulatory arrest, suggesting disordered cerebral metabolism and oxygen use. Although evidence from animal studies suggests potential benefit from very low temperatures, postoperative development of choreoathetosis has been found to correlate with the degree of intraoperative hypothermia, recommending the use of central temperatures greater than 15 degrees C in the clinical practice. Cooling times longer than 20 minutes are needed to obtain homogeneous brain cooling and effective neuroprotection. Finally, there is evidence that the sites of temperature monitoring used in the clinical practice may underestimate brain temperature after cardiopulmonary bypass, with the risk of postoperative hyperthermic brain damage.

Cricoid ring: Shape, size, and variability in infants and children.

BACKGROUND: Knowledge regarding the shape, size, and variability of the cricoid ring is important to properly choose the correct endotracheal tube (ETT) in the pediatric patient. Studies have measured the size of the cricoid ring using methodologies such as moulages, magnetic resonance imaging, and video-bronchoscopy. In the present study, computed tomography (CT) -based images were used to determine the shape, size, and configuration of the cricoid ring in the pediatric population taking into considerations growth and development. METHODS: This is a retrospective review using 130 CT images of children ranging in age from 1 month to 10 years undergoing radiological evaluation unrelated to airway symptomatology. The CT scans were obtained in spontaneously breathing patients during either natural sleep or procedural sedation. Anteroposterior (AP) and transverse (T) diameters were measured at the cricoid ring using these images. RESULTS: The cricoid ring is generally round in children older than 1 year with a T/AP ratio ranging between 0.98 and 1.01. However, in infants (1-12 months of age), the cricoid ring is elliptical with the AP dimension an average of 0.31 mm larger than the T dimension with a T/AP ratio of 0.95. A statistically significant difference between the T and AP dimensions was only observed in infancy (P < 0.05). CONCLUSION: The cricoid ring is round in children older than 1 year of age. In infants, the cricoid shape presents a more elliptical configuration because the T-axis is narrower than the AP dimension. CT is recognized as the most accurate technique to study cricoid ring configuration, and the present data may help clinicians determine the appropriate type, size, and shape of ETTs, particularly in infants.

Postoperative pain management in patients undergoing thoracoscopic repair of pectus excavatum: A retrospective analysis of opioid consumption and adverse effects in adolescents.

INTRODUCTION: Although the Nuss procedure provides excellent cosmetic results for the correction of pectus excavatum, the provision of analgesia following such procedures can be challenging. METHODS: The current study retrospectively reviews our experience over a 2.5 year period with thoracic epidural analgesia (TE), paravertebral blockade (PVB), and intravenous opioids delivered via patient-controlled analgesia (PCA) to provide postoperative analgesia. RESULTS: The study cohort included 30 patients (mean age = 15.6 ± 1.5 years), 15 of whom were treated with PCA, 8 with TE, and 7 with PVB. There were no significant differences in pain scores between the 3 groups at any time point during the first 3 postoperative days. Compared to PCA, the PVB group had lower opioid consumption over the first 24 hours of hospitalization by 1.7 mg/kg morphine equivalents (95% CI of difference: 0.1, 3.3; p=0.035); but had higher opioid consumption by 2.0 mg/kg morphine equivalents than the TE group (95% CI of difference: 0.3, 3.7; p=0.024). There were no differences in opioid consumption between PVB and PCA or between PVB and TE at 48 or 72 hours. The number of intraoperative hypotension episodes was significantly lower in the PCA group when compared to the PVB group (p=0.001), with no difference between the PVB and TE groups. CONCLUSIONS: The use of regional anesthesia should be considered a viable option for the relief of postoperative pain in pediatric patients following the Nuss procedure albeit with a higher incidence of intraoperative hemodynamic effects. A randomized, prospective, study powered to compare all 3 techniques against one another would be necessary to confirm the significance of these findings.