The Impact of Oral Premedication with Midazolam on Respiratory Function in Children

Patient positioning and its impact on perioperative outcomes in children: A narrative review

Patient positioning interacts with a number of body systems and can impact clinically important perioperative outcomes. In this educational review, we present the available evidence on the impact that patient positioning can have in the pediatric perioperative setting. A literature search was conducted using search terms that focused on pediatric perioperative outcomes prioritized by contemporary research in this area. Several key themes were identified: the effects of positioning on respiratory outcomes, cardiovascular outcomes, enteral function, patient and carer-centered outcomes, and soft issue injuries. We encountered considerable heterogeneity in research in this area. There may be a role for lateral positioning to reduce respiratory adverse outcomes, head elevation for intubation and improved oxygenation, and upright positioning to reduce peri-procedural anxiety.

Effect of midazolam in autism spectrum disorder: A retrospective observational analysis

BACKGROUND

While midazolam is commonly used as premedication for uncooperative patients, its effects are difficult to predict in patients with autism spectrum disorder for whom abnormalities in gamma-aminobutyric acid have been reported. This study aimed to investigate the influence of autism spectrum disorder on the effect of midazolam when used as premedication.

METHODS

This retrospective observational study was performed between April 2017 and August 2018. Before inducing general anesthesia with sevoflurane for dental treatment, 390 uncooperative patients received premedication with midazolam. Ordinal logistic regression analysis was performed with the Observer's Assessment of Alertness/Sedation score 30 min after premedication as the objective variable. Age, sex, American Society of Anesthesiologists physical status class, premedication route, dose per body weight, presence of specific disorders (autism spectrum disorder, intellectual disability, epilepsy, cerebral palsy, and other psychiatric disorders), and regular benzodiazepine or non-benzodiazepine psychotropic administration were included as explanatory variables. Kendall's rank correlation coefficient was used to assess the correlation between the Observer's Assessment of Alertness/Sedation score and cooperation level (1, obvious negative response; 2, negative response; 3, positive reaction; 4, obvious positive reaction) during admission and inhalation induction. All data were extracted from anesthesia and medical records.

RESULTS

Age (odds ratio 1.437 [95% confidence interval (CI) 1.213-1.708], P < .001), autism spectrum disorder (1.318 [1.079-1.612], P = .007), benzodiazepine medication (0.574 [0.396-0.827], P = .002), and intramuscular route (1.478 [1.137-1.924], P = .004) were significantly associated with the Observer's Assessment of Alertness/Sedation score, while the score was negatively associated with cooperation levels during admission (τ = -0.714, P < .001) and inhalation induction (τ = -0.606, P < .001).

CONCLUSIONS

Patients with autism spectrum disorder may be susceptible to premedication with midazolam; however, regular benzodiazepine administration may reduce the effect.

Respiratory Adverse Events After LMA® Mask Removal in Children: A Randomized Trial Comparing Propofol to Sevoflurane

BACKGROUND

The removal of the laryngeal mask airway (LMA®) in children may be associated with respiratory adverse events. The rate of occurrence of these adverse events may be influenced by the type of anesthesia. Studies comparing total intravenous anesthesia (TIVA) with propofol and sevoflurane are limited with conflicting data whether propofol is associated with a lower incidence of respiratory events upon removal of LMA as compared to induction and maintenance with sevoflurane. We hypothesized that TIVA with propofol is superior to sevoflurane in providing optimal conditions and improved patient's safety during emergence.

METHODS

In this prospective, randomized, double-blind clinical trial, children aged 6 months to 7 years old were enrolled in 1 of 2 groups: the TIVA group and the sevoflurane group. In both groups, patients were mechanically ventilated. At the end of the procedure, LMAs were removed when patients were physiologically and neurologically recovered to a degree to permit a safe, natural airway. The primary aim of this study was to compare the occurrence of at least 1 respiratory adverse event, the prevalence of individual respiratory adverse events, and the airway hyperreactivity score following emergence from anesthesia between the 2 groups. Secondary outcomes included ease of LMA insertion, quality of anesthesia during the maintenance phase, hemodynamic stability, time to LMA removal, and incidence of emergence agitation.

RESULTS

Children receiving TIVA with propofol had a significantly lower incidence (10.8.% vs 36.2%; relative risk, 0.29; 95% CI [0.14-0.64]; P = .001) and lower severity ( P = .01) of respiratory adverse outcomes compared to the patients receiving inhalational anesthesia with sevoflurane. There were no statistically significant differences in secondary outcomes between the 2 groups, except for emergence agitation that occurred more frequently in patients receiving sevoflurane ( P < .001).

CONCLUSIONS

Propofol induction and maintenance exerted a protective effect on healthy children with minimal risk factors for developing perioperative respiratory complications, as compared to sevoflurane.

Developmental respiratory physiology

Various developmental aspects of respiratory physiology put infants and young children at an increased risk of respiratory failure, which is associated with a higher rate of critical incidents during anesthesia. The immaturity of control of breathing in infants is reflected by prolonged central apneas and periodic breathing, and an increased risk of apneas after anesthesia. The physiology of the pediatric upper and lower airways is characterized by a higher flow resistance and airway collapsibility. The increased chest wall compliance and reduced gas exchange surface of the lungs reduce the pulmonary oxygen reserve vis-à-vis a higher metabolic oxygen demand, which causes more rapid oxygen desaturation when ventilation is compromised. This review describes the various developmental aspects of respiratory physiology and summarizes anesthetic implications.

Video Glasses Reduce Preoperative Anxiety Compared With Portable Multimedia Player in Children: A Randomized Controlled Trial

PURPOSE

Preoperative anxiety in children is challenging for anesthesia providers and nurses. The use of video glasses (VG), an immersive head mount display, helps conceal the unfamiliar operating room environment from the patient's visual field. The aim of this study was to determine the anxiolytic effect of VG compared with that of a portable multimedia player (PMP) during the preoperative period in children.

DESIGN

Prospective randomized trial.

METHODS

Participants were randomized into VG or PMP groups. Patients watched their favorite animation videos using the allocated device from the time of entering the preanesthetic holding area to the end of anesthetic induction. We evaluated modified Yale Preoperative Anxiety Scale scores during anesthetic induction.

FINDINGS

The modified Yale Preoperative Anxiety Scale score in the VG group was significantly lower than that in the PMP group (P = .001).

CONCLUSIONS

In children, the anxiolytic effect of VG during the preoperative period is larger than that of PMP.

Manejo perioperatorio de niños con infección respiratoria superior

Introducción. Es frecuente que muchos niños sometidos a procedimientos con anestesia general tengan historia de infección viral respiratoria superior reciente o activa.Objetivo. Realizar una revisión narrativa acerca de las pautas de manejo anestésico para los niños con infección reciente o activa de la vía aérea superior.Materiales y métodos. Se realizó una búsqueda estructurada de la literatura en las bases de datos ProQuest, EBSCO, ScienceDirect, PubMed, LILACS, Embase, Trip Database, SciELO y Cochrane Library con los términos Anesthesia AND Respiratory Tract Infections AND Complications; Anesthesia AND Upper respiratory tract infection AND Complications; Anesthesia, General AND Respiratory Tract Infections AND Complications; Anesthesia, General AND Upper respiratory tract infection AND Complications; Anesthesia AND Laryngospasm OR Bronchospasm. La búsqueda se hizo en inglés con sus equivalentes en español.Resultados. Se encontraron 56 artículos con información relevante para el desarrollo de la presente revisión.Conclusiones. Una menor manipulación de la vía aérea tiende a disminuir la frecuencia de aparición y severidad de eventos adversos respiratorios perioperatorios. No existe evidencia suficiente para recomendar la optimización medicamentosa en pacientes con infección respiratoria superior.

Deep or awake removal of laryngeal mask airway in children at risk of respiratory adverse events undergoing tonsillectomy-a randomised controlled trial

BACKGROUND

Laryngeal mask airways (LMA) are widely used during tonsillectomies. Contrasting evidence exists regarding the timing of the removal and the risk of perioperative respiratory adverse events. We assessed whether the likelihood of perioperative respiratory adverse events is influenced by the timing of LMA removal in children with at least one risk factor for these events.

METHODS

Participants (n=290, 0-16 yr) were randomised to have their LMA removed either deep (in theatre by anaesthetist at end-tidal sevoflurane >1 minimum alveolar concentration) or awake (in theatre by anaesthetist or in postanaesthesia care unit by anaesthetist or trained nurse). The primary outcome was the occurrence of perioperative respiratory adverse events over the whole emergence and postanaesthesia care unit phases of anaesthesia. The secondary outcome was the occurrence of perioperative respiratory adverse events over the distinct phases of emergence and postanaesthesia care unit.

RESULTS

Data from 283 participants were analysed.

PRIMARY OUTCOME

even though a higher occurrence of adverse events was observed in the awake group, no evidence for a difference was found [45% vs 35%, odds ratio (OR): 1.5, 95% confidence interval (CI): 0.9-2.5, P=0.09]. Secondary outcome: there was no evidence for a difference between the groups during emergence [19 (14%) deep vs 25 (18%) awake, OR: 0.74, 95%CI: 0.39-1.42, P=0.37]. However, in the postanaesthesia care unit, children with an awake rather than deep removal experienced significantly more adverse events [55 (39%) vs 37 (26%); OR: 1.85, 95%CI: 1.12-3.07, P=0.02].

CONCLUSION

We found no evidence for a difference in the timing of the LMA removal on the incidence of respiratory adverse events over the whole emergence and postanaesthesia care unit phases. However, in the postanaesthesia care unit solely, awake removal was associated with significantly more respiratory adverse events than deep removal.

TRIAL REGISTRATION NUMBER

ACTRN12609000387224 (www.anzctr.org.au).

A Comparative Analysis of Preemptive Versus Targeted Sedation on Cardiovascular Stability After High-Risk Cardiac Surgery in Infants

OBJECTIVE

To compare the effect of two sedation practices on cardiovascular stability during the early postoperative period in young infants following cardiac surgery: the routine early use of midazolam infusion (preemptive sedation) and the discretionary use of sedatives tailored to the patient's clinical condition (targeted sedation).

DESIGN

Retrospective cohort study with matched controls.

SETTING

A 15-bedded pediatric cardiac ICU.

PATIENTS

Sedation strategies were compared by matching patients before and after the introduction of a targeted sedation guideline, replacing the existing practice of preemptive sedation. Inclusion criteria were age less than 6 months and cardiopulmonary bypass time greater than 150 minutes. Matching criteria were surgical procedure, age, and duration of cardiopulmonary bypass and cross-clamp. The main outcome was cardiovascular instability, defined by the presence of one of the following criteria in the first 12 hours after PICU admission: 1) simultaneous administration of greater than or equal to two inotropic or vasopressor drugs; 2) administration of greater than 60 mL/kg fluid boluses. Secondary outcomes were: 1) markers of cardiac output adequacy (heart rate, blood pressure, vasoactive inotropic score, urine output, volume of fluid boluses, central venous oxygen saturation, lactate); 2) occurrence of adverse events (cardiac arrest, extracorporeal membrane oxygenation, death); 3) sedatives administered and depth of sedation.

INTERVENTIONS

Introduction of a guideline of targeted sedation.

MEASUREMENTS AND MAIN RESULTS

Thirty-three patients with preemptive sedation were matched to 33 patients with targeted sedation. Targeted sedation resulted in less frequent oversedation, without compromising cardiovascular stability, as indicated by similar occurrence of cardiovascular instability (68.8% with preemptive sedation vs 62.5% with targeted sedation; p = 0.53) and adverse events, and similar markers of cardiac output adequacy. Although all preemptively sedated patients received an infusion of midazolam in the first 12 hours after surgery, only 19.4% of patients in the targeted sedation group received a sedative infusion (p < 0.001).

CONCLUSIONS

Our data suggest that after high-risk cardiac surgery in young infants, routine sedation with midazolam may not prevent low cardiac output syndrome. When accompanied by a careful assessment of level of sedation, routine sedation of infants after high-risk cardiac surgery can be avoided without compromising hemodynamic stability or patient safety. The potential benefit of this approach is reduced exposure to sedative.

The Forced Oscillation Technique in Paediatric Respiratory Practice

The Forced Oscillation Technique (FOT) is a lung function modality based on the application of an external oscillatory signal in order to determine the mechanical response of the respiratory system. The method is in principal noninvasive and requires minimal patient cooperation, which makes it suitable for use in young paediatric patients. The FOT has been successfully applied in various paediatric respiratory disorders, such as asthma, cystic fibrosis, and chronic lung disease of prematurity, in order to assess airway obstruction, bronchodilator response, and airway responsiveness after bronchoprovocation challenge. This technique may be more sensitive than spirometry in identifying disturbances of peripheral airways and assessing the level of asthma control or the effectiveness of therapy at the long term. Further research is required to determine the exact role of the FOT in paediatric lung function testing and to incorporate the method in specific diagnostic and management algorithms.

Dexmedetomidine for infant pulmonary function testing

For the last thirty years, oral chloral hydrate has been used for sedation of infants for lung function testing. Recently, however, availability of chloral hydrate became severely limited in the United States after two manufacturers discontinued manufacturing in 2012. Due to these limitations and the recent and ongoing shortage of chloral hydrate, other medications have been proposed for lung function testing, including midazolam and propofol. Herein, we describe our limited experience using intravenous dexmedetomedine (DMED), a medication thus far described as having minimal effect on pulmonary function or respiratory drive.

Respiratory complications in the pediatric postanesthesia care unit

This article focuses on common respiratory complications in the postanesthesia care unit (PACU). Approximately 1 in 10 children present with respiratory complications in the PACU. The article highlights risk factors and at-risk populations. The physiologic and pathophysiologic background and causes for respiratory complications in the PACU are explained and suggestions given for an optimization of the anesthesia management in the perioperative period. Furthermore, the recognition, prevention, and treatment of these complications in the PACU are discussed.

The neonatal lung--physiology and ventilation

This review article focuses on neonatal respiratory physiology, mechanical ventilation of the neonate and changes induced by anesthesia and surgery. Optimal ventilation techniques for preterm and term neonates are discussed. In summary, neonates are at high risk for respiratory complications during anesthesia, which can be explained by their characteristic respiratory physiology. Especially the delicate balance between closing volume and functional residual capacity can be easily disturbed by anesthetic and surgical interventions resulting in respiratory deterioration. Ventilatory strategies should ideally include application of an 'open lung strategy' as well avoidance of inappropriately high VT and excessive oxygen administration. In critically ill and unstable neonates, for example, extremely low-birthweight infants surgery in the neonatal intensive care unit might be an appropriate alternative to the operating theater. Best respiratory management of neonates during anesthesia is a team effort that should involve a joint multidisciplinary approach of anesthetists, pediatric surgeons, cardiologists, and neonatologists to reduce complications and optimize outcomes in this vulnerable population.

[Anesthesia in spontaneous ventilation for difficult intubation]

Difficult intubation in children is rare and often predictable during anesthesia consultation. This allows to establish a strategy to provide fiberoptic guided tracheal intubation with spontaneous ventilation in function of age and children pathology. A good knowledge of physiologic and anatomic children particularities, of fiberoptic technique and the respect for some principles lead to ensure the security of this procedure. First principle is to use only one anesthetic inhaled or intravenous agent in order to limit an important decrease of ventilation. The anesthetic technique recommended for pediatric fiberoptic guided intubation is inhaled anesthesia with sevoflurane. But it is possible to use an intravenous agent, like propofol, with a continuous infusion (bolus of 0.1 to 0.3 mg/kg then 0.1-0.3mg/kg per hour for maintenance) or with target controlled infusion (Schnider model, initial concentration 2.5 μg/mL, then increase by 0.5 μg/mL steps) particularly in children older than 5 years with an anesthetic depth control. Whatever the agent, the dose must to be titrated to maintain spontaneous ventilation. Second principle is to combine an airway local anesthesia with general anesthesia to limit airway reactivity. First, a nose topical anesthesia is administered with lidocaine plus naphazoline in children older than 2 years. Then, a laryngeal topical anesthesia is realized with lidocaine 1% (1-2 mL, 2mg/kg) through operating channel of fiberoptic bronchoscope. Finally, third principle is to ensure patient oxygenation with several techniques like use of endoscopic facial mask or nasopharyngeal tube. The use of laryngeal mask is a rescue technique in case of spontaneous ventilation lost. In conclusion, each institution has to establish an algorithm with his own knowledge, constantly feasible and regularly taught.