Developmental changes in chest wall compliance in infancy and early childhood

Consideration of the thoracic phenotype of cerebro-costo-mandibular syndrome

Cerebro-costo-mandibular syndrome (CCMS) is a congenital condition with skeletal and orofacial abnormalities that often results in respiratory distress in neonates. The three main phenotypes in the thorax are posterior rib gaps, abnormal costovertebral articulation and absent ribs. Although the condition can be lethal, accurate diagnosis, and subsequent management help improve the survival rate. Mutations in the causative gene SNRPB have been identified, however, the mechanism whereby the skeletal phenotypes affect respiratory function is not well-studied due to the multiple skeletal phenotypes, lack of anatomy-based studies into the condition and rarity of CCMS cases. This review aims to clarify the extent to which the three main skeletal phenotypes in the thorax contribute to respiratory distress in neonates with CCMS. Despite the posterior rib gaps being unique to this condition and visually striking on radiographic images, anatomical consideration, and meta-analyses suggested that they might not be the significant factor in causing respiratory distress in neonates. Rather, the increase in chest wall compliance due to the rib gaps and the decrease in compliance at the costovertebral complex was considered to result in an equilibrium, minimizing the impact of these abnormalities. The absence of floating ribs is likely insignificant as seen in the general population; however, a further absence of ribs or vestigial rib formation is associated with respiratory distress and increased lethality. Based on these, we propose to evaluate the number of absent or vestigial ribs as a priority indicator to develop a personalized treatment plan based on the phenotypes exhibited.

Ultrasound assessment of diaphragm thickness, contractility, and strain in healthy pediatric patients

BACKGROUND

Ultrasound-based diaphragmatic assessments are becoming more common in pediatric acute care, but baseline pediatric diaphragm thickness and contractility values remain unknown.

METHODS

We conducted a prospective, observational study of healthy children aged <18 years undergoing elective surgery. Diaphragm thickness at end-expiration (Tdi-exp), thickening fraction (DTF) and excursion were measured by ultrasound during spontaneous breathing and during mechanical ventilation. Diaphragm strain and peak strain rate were ascertained post hoc. Measurements were compared across a priori specified age groups (<1 year, 1 to <3, 3 to <6, 6 to <12, and 12 to <18 years) and with versus without mechanical ventilation.

RESULTS

Fifty subjects were evaluated (n = 10 per age group). Baseline mean Tdi-exp was 0.19 ± 0.04 cm, DTF 0.19 ± 0.09, excursion 1.69 ± 0.97 cm, strain -10.3 ± 4.9, peak strain rate -0.48 ± 0.21 s-1 . No significant difference in Tdi-exp or DTF was observed across age groups (p > .05). Diaphragm excursion increased with age (p < .0001). Diaphragm strain was significantly greater in the 12-17-year age group (-14.3 ± 6.4), p = .048, but there were no age-related differences in peak strain rate (p = .08). During mechanical ventilation, there were significant decreases in DTF 0.12 ± 0.04 (p < .0001), excursion 1.08 ± 0.31 cm (p < .0001), strain -4.60 ± 1.93 (p < .0001), and peak strain rate -0.20 ± 0.10 s-1 (p < .0001) while there was no change in Tdi-exp 0.18 ± 0.03 cm (p = .25) when compared to baseline values.

CONCLUSION

Pediatric Tdi-exp, DTF, and diaphragm peak strain rate were similar across age groups. Diaphragm excursion and strain varied across age groups. All measures of diaphragm contractility were diminished during mechanical ventilation.

Real-time changes in rib cage expansion and use of abdominal mechanical stimulation in newborns: a quasi-experimental study

OBJECTIVE

To assess the rib cage expansion and respiratory rate in newborns using an abdominal stabilization band.

METHODS

The study included 32 newborns of both genders, with gestational age between 35 and 41 weeks. The abdominal stabilization band was used for 15 minutes between the xiphoid process and the anterosuperior iliac crest, with an abdominal contention 0.5cm smaller than the abdominal circumference. The rib cage expansion was evaluated by a breathing transducer (Pneumotrace II™) three minutes before using the band, during the use (15 minutes), and ten minutes after removing the band. The Shapiro-Wilk test verified data normality, and the Wilcoxon test compared the variables considering rib cage expansion and respiratory rate. Significance was set to p<0.05.

RESULTS

There was an increase in respiratory rate when comparing before and ten minutes after removing (p=0.008) the abdominal stabilization band, as well as when comparing during its use and ten minutes after its removal (p=0.001). There was also an increase in rib cage expansion when comparing before and during the use of the abdominal stabilization band (p=0.005).

CONCLUSIONS

The use of the abdominal stabilization band promoted an increase in the rib cage expansion and respiratory rate in the assessed newborns and may be a viable option to improve the respiratory kinematics of this population.

Effect of intrathoracic oscillations on pulmonary functions in children with cerebral palsy

Objectives

This study was aimed at investigating the effects of intrathoracic oscillations on pulmonary function in children with spastic quadriplegic cerebral palsy.

Methods

This study comprised 24 boys and girls 6-8 years of age with spastic quadriplegic cerebral palsy. According to the modified Ashworth scale, the degree of spasticity was 2 to 2+. The children were able to sit independently and follow instructions. The children were randomly divided into a study group and control group. A spirometer was used to examine each child before and after 6 weeks. Children in the control group received traditional chest physiotherapy (postural drainage and percussion), whereas children in the study group underwent quake device training. For 6 weeks, both groups received four sessions per week. After treatment, the results were collected. Paired t-test and independent-samples t-test were applied to compare the means for each group. p-values <0.05 were considered significant.

Results

The post-treatment results of forced expiratory volume at 1 s, peak expiratory flow, forced vital capacity, and the ratio of forced expiratory volume at 1 s to forced vital capacity demonstrated significant differences favoring the study group over the control group (p < 0.001, p < 0.001, p = 0.002, and p = 0.023, respectively).

Conclusion

Intrathoracic oscillations may improve pulmonary function in children with quadriplegic cerebral palsy.

Diaphragmatic muscle function in term and preterm infants

We aimed to assess the determinants of diaphragmatic function in term and preterm infants. 149 infants (56 term; 93 preterm, of whom 14 were diagnosed with bronchopulmonary dysplasia-BPD) were studied before discharge. Diaphragmatic function was assessed by measurement of the maximum transdiaphragmatic pressure (Pdimax)-a measure of diaphragmatic strength, and the pressure-time index of the diaphragm (PTIdi)-a measure of the load-to-capacity ratio of the diaphragm. The Pdimax was higher in term than preterm infants without BPD (90.1 ± 16.3 vs 81.1 ± 11.8 cmH2O; P = 0.001). Term-born infants also had lower PTIdi compared to preterms without BPD (0.052 ± 0.014 vs 0.060 ± 0.017; P = 0.006). In term and preterm infants without BPD, GA was the most significant predictor of Pdimax and PTIdi, independently of the duration of mechanical ventilation and oxygen support. In infants with GA < 32 weeks (n = 30), the Pdimax was higher in infants without BPD compared to those with BPD (76.1 ± 11.1 vs 65.2 ± 11.9 cmH2O; P = 0.015). Preterms without BPD also had lower PTIdi compared to those with BPD (0.069 ± 0.016 vs 0.109 ± 0.017; P < 0.001). In this subgroup, GA was the only significant independent determinant of Pdimax, while BPD and the GA were significant determinants of the PTIdi.  Conclusions: Preterm infants present lower diaphragmatic strength and impaired ability to sustain the generated force over time, which renders them prone to diaphragmatic fatigue. In very preterm infants, BPD may further aggravate diaphragmatic function. What is Known: • The diaphragm of preterm infants has limited capacity to undertake the work of breathing effectively. • The maximum transdiaphragmatic pressure (a measure of diaphragmatic strength) and the pressure-time index of the diaphragm (a measure of the load-to-capacity ratio of the muscle) have not been extensively assessed in small infants. What is New: • Preterm infants have lower diaphragmatic strength and impaired ability to sustain the generated force over time, which renders them prone to diaphragmatic fatigue. • In very preterm infants, bronchopulmonary dysplasia may further impair diaphragmatic function.

Effect of tidal volume change on pressure-based prediction of fluid responsiveness in children

INTRODUCTION

It is known that pulse pressure variation and systolic pressure variation cannot predict fluid responsiveness in children. In adults, the ability of these dynamic parameters to predict fluid responsiveness is improved by increasing tidal volume. We planned to investigate whether pulse pressure variation or systolic pressure variation can predict fluid responsiveness in children when augmented by increasing tidal volume by conducting a prospective study.

METHODS

We enrolled children younger than 7 years who underwent cardiac surgery for atrial septal defect or ventricular septal defect. After sternum closure, pulse pressure variation and systolic pressure variation were continuously recorded while changing the tidal volume to 6, 10, and 14 mL/kg. Fluid loading was done with 10 mL/kg of crystalloids for 10 min, and stroke volume index was measured via transesophageal echocardiography. Children whose stroke volume index increased by more than 15% after the fluid loading were defined as responders to fluid therapy. We set primary outcome as the predictability of pulse pressure variation and systolic pressure variation for fluid responsiveness and measured the area under the curve of receiver operating characteristics curve.

RESULTS

Twenty-six children were included, of which 15 were responders. At the tidal volume of 14 mL/kg, the area under the curves of receiver operating characteristics curves of pulse pressure variation and systolic pressure variation were 0.576 (p = .517) and 0.548 (p = .678), respectively. The differences in dynamic parameters between responders and nonresponders were not significant.

DISCUSSION

Failure of pulse pressure variation or systolic pressure variation at augmented tidal volume in children may be due to difference in their arterial compliance from those of adults. Large compliance of thoracic wall may be another reason.

CONCLUSIONS

Augmented pulse pressure variation or systolic pressure variation due to increased tidal volume cannot predict fluid responsiveness in children after simple cardiac surgery.

Non-Surgical Respiratory Management in Relation to Feeding and Growth in Patients with Robin Sequence; a Prospective Longitudinal Study

OBJECTIVE

To reflect upon our non-surgical respiratory management by evaluating clinical outcomes regarding airway, feeding, and growth during the first year of life in patients with Robin Sequence.

DESIGN

Prospective study.

SETTING

Sophia Children's Hospital, Rotterdam, the Netherlands.

PATIENTS/ PARTICIPANTS

36 patients with Robin Sequence who were treated between 2011 and 2021.

INTERVENTIONS

Positional therapy and respiratory support.

MAIN OUTCOME MEASURE(S)

Data on respiratory outcomes included polysomnography characteristics and capillary blood gas values. Feeding outcomes were based on the requirement of additional tube feeding. Outcomes on growth were expressed as standard-deviation-scores (SDS) for weight-for-age (WFA) and height-for-age (HFA).

RESULTS

Twenty patients were treated with positional therapy (PT), whilst the other 16 patients required respiratory support. Twenty-two patients presented with non-isolated Robin Sequence (RS). During the first year of life, obstructive apnea hypopnea index decreased, oxygen levels enhanced, and capillary blood gas values improved. Eighty-six percent (31/36) experienced feeding difficulties, which completely resolved in 71% (22/31) during their first year of life. From start treatment, to stop treatment, to the age of 1 year, the SDS WFA worsened from -0.40 to -0.33 to -1.03, respectively.

CONCLUSIONS

Non-surgical respiratory treatment resulted in an improvement of respiratory outcomes to near normal during the first year of life in patients with RS. These patients often experience feeding difficulties and endure impaired weight gain up to 1 year of age, despite near normalization of breathing. The high prevalence of feeding difficulties and impaired weight for age indicate the urgency for early recognition and adequate treatment to support optimal growth.

Pediatric Chest Compression Improvement Via Augmented Reality Cardiopulmonary Resuscitation Feedback in Community General Emergency Departments: A Mixed-Methods Simulation-Based Pilot Study

BACKGROUND

Yearly, more than 20,000 children experience a cardiac arrest. High-quality pediatric cardiopulmonary resuscitation (CPR) is generally challenging for community hospital teams, where pediatric cardiac arrest is infrequent. Current feedback systems are insufficient. Therefore, we developed an augmented reality (AR) CPR feedback system for use in many settings.

OBJECTIVE

We aimed to evaluate whether AR-CPR improves chest compression (CC) performance in non-pediatric-specialized community emergency departments (EDs).

METHODS

We performed an unblinded, randomized, crossover simulation-based study. A convenience sample of community ED nonpediatric nurses and technicians were included. Each participant performed three 2-min cycles of CC during a simulated pediatric cardiac arrest. Participants were randomized to use AR-CPR in one of three CC cycles. Afterward, participants participated in a qualitative interview to inquire about their experience with AR-CPR.

RESULTS

Of 36 participants, 18 were randomized to AR-CPR in cycle 2 (group A) and 18 were randomized to AR-CPR in cycle 3 (group B). When using AR-CPR, 87-90% (SD 12-13%) of all CCs were in goal range, analyzed as 1-min intervals, compared with 18-21% (SD 30-33%) without feedback (p < 0.001). Analysis of qualitative themes revealed that AR-CPR may be usable without a device orientation, be effective at cognitive offloading, and reduce anxiety around and enhance confidence in the CC delivered.

CONCLUSIONS

The novel CPR feedback system, AR-CPR, significantly changed the CC performance in community hospital non-pediatric-specialized general EDs from 18-21% to 87-90% of CC epochs at goal. This study offers preliminary evidence suggesting AR-CPR improves CC quality in community hospital settings.

Changes in ventilation modes in the last decade and their impact on the prevalence of bronchopulmonary dysplasia in preterm infants

BACKGROUND

Less invasive forms of ventilation have evolved aiming to decrease bronchopulmonary dysplasia (BPD) morbidity. It is unclear whether changes in ventilation practices have been associated with improvements in respiratory outcomes.

OBJECTIVE

To examine the changes in ventilation modes in preterm neonates between two periods during the last decade and their impact on BPD prevalence.

METHODS

A retrospective chart review of very low birth weight infants and those born at less than 32 weeks gestation hospitalized during two periods: the years 2012-2013 and 2018-2019. The primary outcome was the prevalence of BPD. Study variables included the mode and duration of ventilation, duration of oxygen need, and perinatal clinical parameters.

RESULTS

Four hundred eighty-one infants were enrolled. Between the two study periods, a significant increase was observed in invasive (33%-47%, p = 0.002), and noninvasive ventilation rates (44%-72%, p < 0.001). The average duration of noninvasive ventilation increased significantly (from 9.24 to 14.08 days, p = 0.016). The total duration of respiratory support remained unchanged. The overall prevalence of moderate and severe BPD at 36 weeks corrected age remained approximately 40% in preterm infants born at less than 28 weeks gestation.

CONCLUSION

The increasing use of non-invasive ventilation was not accompanied by a reduction in the use of invasive ventilation, nor by a reduced prevalence of BPD. The high prevalence of BPD remains a significant problem in extreme prematurity. Other interventions, in addition to less aggressive ventilation, need to be explored.

A new method of ventilation inhomogeneity assessment based on a simulation study using clinical data on congenital diaphragmatic hernia cases

Congenital Diaphragmatic Hernia (CDH) is a diaphragm defect associated with lung hypoplasia and ventilation inhomogeneity (VI). The affected neonates are usually born with respiratory failure and require mechanical ventilation after birth. However, significant interindividual VI differences make ventilation difficult. So far, there are no clinical methods of VI assessment that could be applied to optimize ventilation at the bedside. A new VI index is a ratio of time constants T₁/T₂ of gas flows in both lungs. Pressure-controlled ventilation simulations were conducted using an infant hybrid (numerical-physical) respiratory simulator connected to a ventilator. The parameters of the respiratory system model and ventilator settings were based on retrospective clinical data taken from three neonates (2, 2.6, 3.6 kg) treated in the Paediatric Teaching Clinical Hospital of the Medical University of Warsaw. We searched for relationships between respiratory system impedance (Z) and ventilation parameters: work of breathing (WOB), peak inspiratory pressure (PIP), and mean airway pressure (MAP). The study showed the increased VI described by the T₁/T₂ index value highly correlated with elevated Z, WOB, PIP and MAP (0.8-0.9, the Spearman correlation coefficients were significant at P < 0.001). It indicates that the T₁/T₂ index may help to improve the ventilation therapy of CDH neonates.

Neonatal abdominal support to address CPAP belly: Two cases report and literature review

Gaseous distension of the abdomen from the use of continuous positive airway pressure (CPAP) in the preterm population is of increasing concern for its unintended consequences. Methods to treat and prevent CPAP belly deserve further investigation. An intervention to provide abdominal support to address CPAP belly is presented in these case studies.

Inspiratory Muscle Rehabilitation Training in Pediatrics: What Is the Evidence?

Pulmonary rehabilitation is typically used for reducing respiratory symptoms and improving fitness and quality of life for patients with chronic lung disease. However, it is rarely prescribed and may be underused in pediatric conditions. Pulmonary rehabilitation can include inspiratory muscle training that improves the strength and endurance of the respiratory muscles. The purpose of this narrative review is to summarize the current literature related to inspiratory muscle rehabilitation training (IMRT) in healthy and diseased pediatric populations. This review highlights the different methods of IMRT and their effects on respiratory musculature in children. Available literature demonstrates that IMRT can improve respiratory muscle strength and endurance, perceived dyspnea and exertion, maximum voluntary ventilation, and exercise performance in the pediatric population. These mechanistic changes help explain improvements in symptomology and clinical outcomes with IMRT and highlight our evolving understanding of the role of IMRT in pediatric patients. There remains considerable heterogeneity in the literature related to the type of training utilized, training protocols, duration of the training, use of control versus placebo, and reported outcome measures. There is a need to test and refine different IMRT protocols, conduct larger randomized controlled trials, and include patient-centered clinical outcomes to help improve the evidence base and support the use of IMRT in patient care.

Paediatric chest compression performance improves via novel augmented-reality cardiopulmonary resuscitation feedback system: A mixed-methods pilot study in a simulation-based setting

Aim

More than 20,000 children experience a cardiac arrest event each year in the United States. Most children do not survive. High-quality cardiopulmonary resuscitation (CPR) has been associated with improved outcomes yet adherence to guidelines is poor. We developed and tested an augmented reality head mounted display chest compression (CC) feedback system (AR-CPR) designed to provide real-time CC feedback and guidance.

Methods

We conducted an unblinded randomized crossover simulation-based study to determine whether AR-CPR changes a user's CC performance. A convenience sample of healthcare providers who perform CC on children were included. Subjects performed three two-minute cycles of CC during a simulated 18-minute paediatric cardiac arrest. Subjects were randomized to utilize AR-CPR in the second or third CC cycle. After, subjects participated in a qualitative portion to inquire about their experience with AR-CPR and offer criticisms and suggestions for future development.

Results

There were 34 subjects recruited. Sixteen subjects were randomly assigned to have AR-CPR in cycle two (Group A) and 18 subjects were randomized to have AR-CPR in cycle three (Group B). There were no differences between groups CC performance in cycle one (baseline). In cycle two, subjects in Group A had 73% (SD 18%) perfect CC epochs compared to 17% (SD 26%) in Group B (p < 0.001). Overall, subjects enjoyed using AR-CPR and felt it improved their CC performance.

Conclusion

This novel AR-CPR feedback system showed significant CC performance change closer to CC guidelines. Numerous hardware, software, and user interface improvements were made during this pilot study.

Pediatric anesthesia and achalasia: 10 years' experience in peroral endoscopy myotomy management

BACKGROUND

Endoscopic treatment for achalasia (POEM) is a recently introduced technique that incorporates the concepts of natural orifice transluminal surgery. Although pediatric achalasia is rare, POEM has been episodically used in children since 2012. Despite this procedure entails many implications for airway management and mechanical ventilation, evidences about anesthesiologic management are very poor. We conducted this retrospective study to pay attention on the clinical challenge for pediatric anesthesiologists. We put special emphasis on the risk in intubation maneuvers and in ventilation settings.

RESULTS

We retrieved data on children 18 years old and younger who underwent POEM in a single tertiary referral endoscopic center between 2012 and 2021. Demographics, clinical history, fasting status, anesthesia induction, airway management, anesthesia maintenance, timing of anesthesia and procedure, PONV, and pain treatment and adverse events were retrieved from the original database. Thirty-one patients (3-18 years) undergoing POEM for achalasia were analyzed. In 30 of the 31 patients, rapid sequence induction was performed. All patients manifested consequences of endoscopic CO₂ insufflation and most of them required a new ventilator approach. No life-threatening adverse events have been detected.

CONCLUSIONS

POEM procedure seems to be characterized by a low-risk profile, but specials precaution must be taken. The inhalation risk is actually due to the high rate of full esophagus patients, even if the Rapid Sequence Induction was effective in preventing ab ingestis pneumonia. Mechanical ventilation may be difficult during the tunnelization step. Future prospective trials will be necessary to individuate the better choices in such a special setting.

Effects of fentanyl overdose-induced muscle rigidity and dexmedetomidine on respiratory mechanics and pulmonary gas exchange in sedated rats

The objective of our study was to establish in sedated rats the consequences of high-dose fentanyl-induced acute muscle rigidity on the mechanical properties of the respiratory system and on the metabolic rate. Doses of fentanyl that we have previously shown to produce persistent rigidity of the muscles of the limbs and trunk in the rat (150 -300 microg/kg iv), were administered in 23 volume-controlled mechanically ventilated and sedated rats. The effects of a low dose of the FDA approved central alpha-2 agonist, dexmedetomidine (3 microg/kg iv), which has been suggested to oppose fentanyl-induced muscle rigidity, were determined after fentanyl administration. Fentanyl produced a significant decrease in Crs in the 23 rats that were studied. In 13 rats, an abrupt response occurred within 90 seconds, consisting in rapid rhythmic contractions of most skeletal muscles, that were replaced by persistent tonic/tetanic contractions leading a significant decrease of Crs (from 0.51 ± 0.11 ml/cmH₂O to 0.36 ± 0.08 ml/cmH₂O, 3 minutes after fentanyl injection). In the other 10 animals, a Crs progressively decreased to 0.26 ± 0.06 ml/cmH₂O at 30 minutes. There was a significant rise in V̇O₂ during muscle tonic contractions (from 8.48 ± 4.31 to 11.29 ± 2.57 ml/min), which contributed to a significant hypoxemia, despite ventilation being held constant. Dexmedetomidine provoked a significant and rapid increase in Crs towards baseline levels, while decreasing the metabolic rate and restoring normoxemia. We propose that the changes in respiratory mechanics and metabolism produced by opioid-induced muscle rigidity contribute to fentanyl lethality.

Impact of airway and a standardized recruitment maneuver on CT chest imaging quality in a pediatric population: A retrospective review

INTRODUCTION

When performing computerized tomography chest imaging in children, obtaining high quality, motion-free images is important in the accurate diagnosis of underlying pathology. General anesthesia is associated with the development of atelectasis, which can impair accurate diagnosis by obscuring or altering the appearance of the lung parenchyma or airways. Recruitment maneuvers, performed by anesthesiologists, can be used to effectively re-expand atelectatic lung.

METHODS

The computerized tomography chest imaging in 44 children aged between 2 months and 7 years, undergoing serial imaging for monitoring of cystic fibrosis, were reviewed and graded for atelectasis. The first scan performed on each child was performed with a supraglottic airway device and a non-standardized recruitment maneuver. The second scan on each child was performed with a cuffed endotracheal tube and a standardized recruitment maneuver.

RESULTS

When a supraglottic airway device and a non-standardized recruitment maneuver were used, 77% of patients demonstrated atelectasis of any degree on their computerized tomography chest imaging, compared with only 39% when a cuffed endotracheal tube and standardized recruitment maneuver were used. The percentage of computerized tomography chest scans that were scored acceptable (with either a total combined lung atelectasis score of 0 or 1) improved from 37% to 75% when a cuffed endotracheal tube and standardized recruitment maneuver were used. In particular, the mean atelectasis score for both lungs improved from 2.91 (SD ± 2.6) to 1.11 (SD ± 1.9), with a mean difference of 1.8 (95% CI 0.82-2.77; p: .0004).

CONCLUSION

The use of a cuffed endotracheal tube and a standardized recruitment maneuver is an effective way to reduce atelectasis as a result of general anesthesia. Anesthesiologists can actively contribute toward improved image quality through their choice of airway and recruitment maneuver.

Mechanical Ventilation in Pediatric and Neonatal Patients

Pediatric acute respiratory distress syndrome (PARDS) remains a significant cause of morbidity and mortality, with mortality rates as high as 50% in children with severe PARDS. Despite this, pediatric lung injury and mechanical ventilation has been poorly studied, with the majority of investigations being observational or retrospective and with only a few randomized controlled trials to guide intensivists. The most recent and universally accepted guidelines for pediatric lung injury are based on consensus opinion rather than objective data. Therefore, most neonatal and pediatric mechanical ventilation practices have been arbitrarily adapted from adult protocols, neglecting the differences in lung pathophysiology, response to injury, and co-morbidities among the three groups. Low tidal volume ventilation has been generally accepted for pediatric patients, even in the absence of supporting evidence. No target tidal volume range has consistently been associated with outcomes, and compliance with delivering specific tidal volume ranges has been poor. Similarly, optimal PEEP has not been well-studied, with a general acceptance of higher levels of F_iO₂ and less aggressive PEEP titration as compared with adults. Other modes of ventilation including airway pressure release ventilation and high frequency ventilation have not been studied in a systematic fashion and there is too little evidence to recommend supporting or refraining from their use. There have been no consistent outcomes among studies in determining optimal modes or methods of setting them. In this review, the studies performed to date on mechanical ventilation strategies in neonatal and pediatric populations will be analyzed. There may not be a single optimal mechanical ventilation approach, where the best method may simply be one that allows for a personalized approach with settings adapted to the individual patient and disease pathophysiology. The challenges and barriers to conducting well-powered and robust multi-institutional studies will also be addressed, as well as reconsidering outcome measures and study design.

Atelectasis and lung recruitment in pediatric anesthesia: An educational review

General anesthesia is associated with development of pulmonary atelectasis. Children are more vulnerable to the development and adverse effects of atelectasis. We review the physiology and risk factors for the development of atelectasis in pediatric patients under general anesthesia. We discuss the clinical significance of atelectasis, the use and value of recruitment maneuvers, and other techniques available to minimize lung collapse. This review demonstrates the value of a recruitment maneuver, maintaining positive end-expiratory pressure (PEEP) until extubation and lowering FiO₂ where possible in the daily practice of the pediatric anesthetist.

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.

Respiratory muscle function in the newborn: a narrative review

Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure-time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. IMPACT: Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.

Established severe BPD: is there a way out? Change of ventilatory paradigms

Improved survival of extremely preterm newborn infants has increased the number of infants at risk for developing bronchopulmonary dysplasia (BPD). Despite efforts to prevent BPD, many of these infants still develop severe BPD (sBPD) and require long-term invasive mechanical ventilation. The focus of research and clinical management has been on the prevention of BPD, which has had only modest success. On the other hand, research on the management of the established sBPD patient has received minimal attention even though this condition poses large economic and health problems with extensive morbidities and late mortality. Patients with sBPD, however, have been shown to respond to treatments focused not only on ventilatory strategies but also on multidisciplinary approaches where neurodevelopmental support, growth promoting strategies, and aggressive treatment of pulmonary hypertension improve their long-term outcomes. In this review we will try to present a physiology-based ventilatory strategy for established sBPD, emphasizing a possible paradigm shift from acute efforts to wean infants at all costs to a more chronic approach of stabilizing the infant. This chronic approach, herein referred to as chronic phase ventilation, aims at allowing active patient engagement, reducing air trapping, and improving ventilation-perfusion matching, while providing sufficient support to optimize late outcomes. IMPACT: Based on pathophysiological aspects of evolving and established severe BPD in premature infants, this review presents some lung mechanical properties of the most severe phenotype and proposes a chronic phase ventilatory strategy that aims at reducing air trapping, improving ventilation-perfusion matching and optimizing late outcomes.

Dynamic variables predict fluid responsiveness in pre-school and school children undergoing neurosurgery: a prospective observational study

BACKGROUND

The evidence that plethysmographic variability index (PVI), pulse pressure variation (PPV), FloTrac/Vigileo-derived stroke volume variation (SVV), and Ea_dyn (dynamic arterial elastance) predict fluid responsiveness in children is limited by conflicting results. We aim to evaluate their accuracy and reliability to predict fluid responsiveness after induction in children aged 4-9 years undergoing major neurosurgery.

METHODS

Children aged 4-9 years undergoing intracranial epileptic foci excision were enrolled. After the induction of anesthesia, fluid loading with 10 mL/kg of Ringer's solution over 10 min was administered before surgical incision. PVI, PPV, SVV, and Ea_dyn were measured before and within 5 min after fluid loading. Respiratory variation in aortic blood flow peak velocity (∆Vpeak) >15% at baseline, measured using transthoracic echocardiography, identified fluid "responders". The abilities of dynamic variables to predict an increase in mean arterial pressure (MAP) of >10% following fluid loading were also assessed.

RESULTS

Fourteen (31.8%) of forty-four patients were responders defined by a baseline ∆Vpeak >15%. Before fluid loading, only the PVI value was significantly different between R and NR (P=0.017). Baseline PVI showed fair diagnostic accuracy for fluid responsiveness, with an area under the curve (AUROC) of 0.735 and the cutoff value of 13%. The R group showed a significantly greater absolute change in PPV and SVV after fluid loading from baseline compared with the NR group (P=0.021 and 0.040, respectively). The absolute change in the PPV and SVV values from baseline was greater in R than those in NR (P=0.021 and 0.040, respectively). Twenty (45.5%) showed a MAP increase of >10% following fluid loading and were defined as responders. Baseline ∆Vpeak and SVV showed fair predictive values for a MAP increase of >10% (AUROC =0.758 and 0.715, respectively).

CONCLUSIONS

PVI at baseline showed fair reliability to predict fluid responsiveness after anesthesia induction in mechanically ventilated children aged 4-9 years undergoing neurosurgery. Baseline ∆Vpeak and SVV were fairly predictive for an increase in MAP following fluid loading.

Trends in Pediatric Patient-Ventilator Asynchrony During Invasive Mechanical Ventilation

OBJECTIVES

To explore the level and time course of patient-ventilator asynchrony in mechanically ventilated children and the effects on duration of mechanical ventilation, PICU stay, and Comfort Behavior Score as indicator for patient comfort.

DESIGN

Secondary analysis of physiology data from mechanically ventilated children.

SETTING

Mixed medical-surgical tertiary PICU in a university hospital.

PATIENTS

Mechanically ventilated children 0-18 years old were eligible for inclusion. Excluded were patients who were unable to initiate and maintain spontaneous breathing from any cause.

MEASUREMENTS AND MAIN RESULTS

Twenty-nine patients were studied with a total duration of 109 days. Twenty-two study days (20%) were excluded because patients were on neuromuscular blockade or high-frequency oscillatory ventilation, yielding 87 days (80%) for analysis. Patient-ventilator asynchrony was detected through analysis of daily recorded ventilator airway pressure, flow, and volume versus time scalars. Approximately one of every three breaths was asynchronous. The percentage of asynchronous breaths significantly increased over time, with the highest prevalence on the day of extubation. There was no correlation with the Comfort Behavior score. The percentage of asynchronous breaths during the first 24 hours was inversely correlated with the duration of mechanical ventilation. Patients with severe patient-ventilator asynchrony (asynchrony index > 10% or > 75th percentile of the calculated asynchrony index) did not have a prolonged duration of ventilation.

CONCLUSIONS

The level of patient-ventilator asynchrony increased over time was not related to patient discomfort and inversely related to the duration of mechanical ventilation.

Modes and strategies for providing conventional mechanical ventilation in neonates

Neonatal respiratory failure is a common and serious clinical problem which in a considerable proportion of infants requires invasive mechanical ventilation. The basic goal of mechanical ventilation is to restore lung function while limiting ventilator-induced lung injury, which is considered an important risk factor in the development of bronchopulmonary dysplasia (BPD). Over the last decades, new conventional mechanical ventilation (CMV) modalities have been introduced in clinical practice, aiming to assist clinicians in providing lung protective ventilation strategies. These modalities use more sophisticated techniques to improve patient-ventilator interaction and transfer control of ventilation from the operator to the patient. Knowledge on how these new modalities work and how they interact with lung physiology is essential for optimal and safe use. In this review, we will discuss some important basic lung physiological aspects for applying CMV, the basic principles of the old and new CMV modalities, and the evidence to support their use in daily clinical practice.

Impact of extensive negative pressure wound therapy on neonatal respiration: A case report

An extensive topical negative pressure wound therapy (NPWT) from the abdominal to chest walls in neonates may decrease the compliance of the chest wall. Therefore, it is important to monitor respiratory function carefully during the procedure.

Evolution of inspiratory muscle function in children during mechanical ventilation

BACKGROUND

There is no universally accepted method to assess the pressure-generating capacity of inspiratory muscles in children on mechanical ventilation (MV), and no study describing its evolution over time in this population.

METHODS

In this prospective observational study, we have assessed the function of the inspiratory muscles in children on various modes of MV. During brief airway occlusion maneuvers, we simultaneously recorded airway pressure depression at the endotracheal tube (ΔPaw, force generation) and electrical activity of the diaphragm (EAdi, central respiratory drive) over five consecutive inspiratory efforts. The neuro-mechanical efficiency ratio (NME, ΔPaw/EAdimax) was also computed. The evolution over time of these indices in a group of children in the pediatric intensive care unit (PICU) was primarily described. As a secondary objective, we compared these values to those measured in a group of children in the operating room (OR).

RESULTS

In the PICU group, although median NMEoccl decreased over time during MV (regression coefficient - 0.016, p = 0.03), maximum ΔPawmax remained unchanged (regression coefficient 0.109, p = 0.50). Median NMEoccl at the first measurement in the PICU group (after 21 h of MV) was significantly lower than at the only measurement in the OR group (1.8 cmH2O/µV, Q1-Q3 1.3-2.4 vs. 3.7 cmH2O/µV, Q1-Q3 3.5-4.2; p = 0.015). Maximum ΔPawmax in the PICU group was, however, not significantly different from the OR group (35.1 cmH2O, Q1-Q3 21-58 vs. 31.3 cmH2O, Q1-Q3 28.5-35.5; p = 0.982).

CONCLUSIONS

The function of inspiratory muscles can be monitored at the bedside of children on MV using brief airway occlusions. Inspiratory muscle efficiency was significantly lower in critically ill children than in children undergoing elective surgery, and it decreased over time during MV in critically ill children. This suggests that both critical illness and MV may have an impact on inspiratory muscle efficiency.

Respiratory synchrony comparison between preterm and full-term neonates using inertial sensors

INTRODUCTION

Due to inefficient respiratory control, newborns become prone to asynchronous thoracoabdominal (TA) movements. The present study quantitatively estimated the synchrony of TA in preterm and full-term newborns through an inertial and magnetic measurement units (IMMUs) system.

METHODS

This cross-sectional study was conducted with 20 newborns divided into Preterm Group (PTG, n = 10) and Full-Term Group (FTG, n = 10). Each neonate had IMMUs placed on the sternum and near the umbilicus, thus the TA motion was estimated through the resultant inclination angles calculated using a sensor fusion filter. The respiratory incursions were also manually counted and video-recorded for two minutes, then used to validate a Matlab custom-written routine for their automatic identification. The respiratory cycles were used to calculate the phase change angle (φ) between the thoracic and abdominal compartments. Association between the manual and automatic methods were verified by Pearson's correlation and root mean squared errors (RMSE), and the comparison between the groups was performed through the Student's t test with α = .05.

RESULTS

The values of respiratory incursions measured by both methods showed a high association and low measurement error (r = .96, RMSE = 9.8, p < .001). The FTG presented a higher occurrence of TA synchrony (p = .049) while the PTG group presented a higher occurrence of TA asynchrony (p = .036). No difference was found between the groups regarding the paradoxical classification (p = .071).

CONCLUSION

The proposed method was valid to quantitatively assess the TA synchrony of hospitalized neonates. Preterm infants had a higher occurrence of the asynchronous respiratory pattern in comparison to full-term infants.

55th Harrington Lecture: The respiratory impact of EOS and its therapies: where are we and where do we go from here?

The following lecture was delivered at the Scoliosis Research Society annual meeting in 2020. It addresses our current knowledge about the respiratory impact of Early Onset Scoliosis, the limitations in the data that have been published, and the opportunity for further clinical research in the field.

Relationship between thoracoabdominal mobility and hours of life in infants: A cross-sectional study

Assessing the relationship between thoracoabdominal mobility (TAM) in newborns (NBs) is relevant for a greater understanding of pulmonary kinematics. This study aimed to assess the association between TAM, hours of life and respiratory rate (RR) in term NBs. Healthy NBs were included in the sample. They were filmed for 2 min, with markers in the lateral region of the trunk, delimiting the thoracic and abdominal areas. TAM and RR were assessed using a MATLAB® routine. For kinematic analysis, an algorithm created graphs presenting thoracoabdominal mobility. A total of 26 NBs were evaluated. TAM was the only variable that exhibited a statistically significant intergroup difference, showing that the fewer the hours of life, the greater the mobility. Simple linear regression analysis showed that RR can explain 31% of the variation in abdominal mobility (p = 0.002). Thus, the fewer the hours of life, the greater the TAM of NBs, with a predominance of abdominal compartment mobility.

Physiological changes and compensatory mechanisms by the action of respiratory muscles in a porcine model of phrenic nerve injury

Phrenic nerve damage may occur as a complication of specific surgical procedures, prolonged mechanical ventilation, or physical trauma. The consequent diaphragmatic paralysis or dysfunction can lead to major complications. The purpose of this study was to elucidate the role of the nondiaphragmatic respiratory muscles during partial or complete diaphragm paralysis induced by unilateral and bilateral phrenic nerve damage at different levels of ventilatory pressure support in an animal model. Ten pigs were instrumented, the phrenic nerve was exposed from the neck, and spontaneous respiration was preserved at three levels of pressure support, namely, high, low, and null, at baseline condition, after left phrenic nerve damage, and after bilateral phrenic nerve damage. Breathing pattern, thoracoabdominal volumes and asynchrony, and pressures were measured at each condition. Physiological breathing was predominantly diaphragmatic and homogeneously distributed between right and left sides. After unilateral damage, the paralyzed hemidiaphragm was passively dragged by the ipsilateral rib cage muscles and the contralateral hemidiaphragm. After bilateral damage, the drive to and the work of breathing of rib cage and abdominal muscles increased, to compensate for diaphragmatic paralysis, ensuing paradoxical thoracoabdominal breathing. Increasing level of pressure support ventilation replaces this muscle group compensation. When the diaphragm is paralyzed (unilaterally and/or bilaterally), there is a coordinated reorganization of nondiaphragmatic respiratory muscles as compensation that might be obscured by high level of pressure support ventilation. Noninvasive thoracoabdominal volume and asynchrony assessment could be useful in phrenic nerve-injured patients to estimate the extent and type of inspiratory muscle dysfunction.NEW & NOTEWORTHY This was the first (to our knowledge) implanted porcine model of phrenic nerve injury with a detailed multidimensional analysis of different degrees of diaphragmatic paralysis (unilateral and bilateral). Noninvasive thoracoabdominal volume and asynchrony assessment was shown to be useful in estimating the extent of diaphragmatic dysfunction and the consequent coordinated reorganization of nondiaphragmatic respiratory muscles. High level of pressure support ventilation was proved to obscure the interaction and compensation of respiratory muscles to deal with phrenic nerve injury.

Aerosol drug delivery to spontaneously-breathing preterm neonates: lessons learned

Delivery of medications to preterm neonates receiving non-invasive ventilation (NIV) represents one of the most challenging scenarios for aerosol medicine. This challenge is highlighted by the undersized anatomy and the complex (patho)physiological characteristics of the lungs in such infants. Key physiological restraints include low lung volumes, low compliance, and irregular respiratory rates, which significantly reduce lung deposition. Such factors are inherent to premature birth and thus can be regarded to as the intrinsic factors that affect lung deposition. However, there are a number of extrinsic factors that also impact lung deposition: such factors include the choice of aerosol generator and its configuration within the ventilation circuit, the drug formulation, the aerosol particle size distribution, the choice of NIV type, and the patient interface between the delivery system and the patient. Together, these extrinsic factors provide an opportunity to optimize the lung deposition of therapeutic aerosols and, ultimately, the efficacy of the therapy.

In this review, we first provide a comprehensive characterization of both the intrinsic and extrinsic factors affecting lung deposition in premature infants, followed by a revision of the clinical attempts to deliver therapeutic aerosols to premature neonates during NIV, which are almost exclusively related to the non-invasive delivery of surfactant aerosols. In this review, we provide clues to the interpretation of existing experimental and clinical data on neonatal aerosol delivery and we also describe a frame of measurable variables and available tools, including in vitro and in vivo models, that should be considered when developing a drug for inhalation in this important but under-served patient population.

Integrative Computational Models of Lung Structure-Function Interactions

Anatomically based integrative models of the lung and their interaction with other key components of the respiratory system provide unique capabilities for investigating both normal and abnormal lung function. There is substantial regional variability in both structure and function within the normal lung, yet it remains capable of relatively efficient gas exchange by providing close matching of air delivery (ventilation) and blood delivery (perfusion) to regions of gas exchange tissue from the scale of the whole organ to the smallest continuous gas exchange units. This is despite remarkably different mechanisms of air and blood delivery, different fluid properties, and unique scale-dependent anatomical structures through which the blood and air are transported. This inherent heterogeneity can be exacerbated in the presence of disease or when the body is under stress. Current computational power and data availability allow for the construction of sophisticated data-driven integrative models that can mimic respiratory system structure, function, and response to intervention. Computational models do not have the same technical and ethical issues that can limit experimental studies and biomedical imaging, and if they are solidly grounded in physiology and physics they facilitate investigation of the underlying interaction between mechanisms that determine respiratory function and dysfunction, and to estimate otherwise difficult-to-access measures. © 2021 American Physiological Society. Compr Physiol 11:1501-1530, 2021.

Structural and functional development in airways throughout childhood: Children are not small adults

Children are not small adults and this fact is particularly true when we consider the respiratory tract. The anatomic peculiarities of the upper airway make infants preferential nasal breathers between 2 and 6 months of life. The pediatric larynx has a more complex shape than previously believed, with the narrowest point located anatomically at the subglottic level and functionally at the cricoid cartilage. Alveolarization of the distal airways starts conventionally at 36-37 weeks of gestation, but occurs mainly after birth, continuing until adolescence. The pediatric chest wall has unique features that are particularly pronounced in infants. Neonates, infants, and toddlers have a higher metabolic rate, and consequently, their oxygen consumption at rest is more than double that of adults. The main anatomical and functional differences between pediatric and adult airways contribute to the understanding of various respiratory symptoms and disease conditions in childhood. Knowing the peculiarities of pediatric airways is helpful in the prevention, management, and treatment of acute and chronic diseases of the respiratory tract. Developmental modifications in the structure of the respiratory tract, in addition to immunological and neurological maturation, should be taken into consideration during childhood.

Respiratory Mechanics: To Balance the Mechanical Breaths!!

How to cite this article: Sundaram M, Karthika M. Respiratory Mechanics: To Balance the Mechanical Breaths!!. Indian J Crit Care Med 2021;25(1):10-11.

Evaluation of nebulized N-acetyl cysteine in outcome of esophageal atresia with tracheoesophegeal fistula

AIM

To evaluate the role of nebulized N-acetyl cysteine (NAC) in liquefying the airway secretions and improving the outcome of patients of esophageal atresia with tracheoesophageal fistula (EA + TEF).

METHODS

It was a non-randomized interventional study. Two milliliters of 10% NAC was given in a nebulized form (2:5 dilution, every six hourly) to patients of ET + TEF, along with regular suction of upper esophageal pouch. The group was compared with control, which comprised patients of EA + TEF receiving only saline nebulization. The consistency of the secretions was compared by hand held consistometer in unit of time (seconds) required to cross a predetermined distance along with gravity.

RESULTS

Sixty patients were assessed. Of these, 30 patients were present in both groups. The study group showed significant (p = 0.01-0.0001) decrease in consistency of secretions from the control group after day 2 of NAC nebulization. Patients' discharge was significantly (p = 0.01) earlier in cases. There was no significant (p = 0.41) difference in mortality between the groups. No specific adverse effects were observed in the study group.

CONCLUSION

It appears that nebulized NAC decreases the consistency of secretions in EA + TEF patients. It is interesting to note that the group of patients that received NAC was discharged earlier than the control group and had a higher survival rate than the control group. Whether this is directly attributable to the use of NAC is unknown. A prospective double-blinded randomized clinical trial is warranted to confirm these results.

LEVEL OF EVIDENCE

Level II, prospective comparative study (non-randomized).

Additional work of breathing from trigger errors in mechanically ventilated children

Background

Patient–ventilator asynchrony is associated with increased morbidity and mortality. A direct causative relationship between Patient–ventilator asynchrony and adverse clinical outcome have yet to be demonstrated. It is hypothesized that during trigger errors excessive pleural pressure swings are generated, contributing to increased work-of-breathing and self-inflicted lung injury. The objective of this study was to determine the additional work-of-breathing and pleural pressure swings caused by trigger errors in mechanically ventilated children.

Methods

Prospective observational study in a tertiary paediatric intensive care unit in an university hospital. Patients ventilated > 24 h and < 18 years old were studied. Patients underwent a 5-min recording of the ventilator flow–time, pressure–time and oesophageal pressure–time scalar. Pressure–time–product calculations were made as a proxy for work-of-breathing. Oesophageal pressure swings, as a surrogate for pleural pressure swings, during trigger errors were determined.

Results

Nine-hundred-and-fifty-nine trigger errors in 28 patients were identified. The additional work-of-breathing caused by trigger errors showed great variability among patients. The more asynchronous breaths were present the higher the work-of-breathing of these breaths. A higher spontaneous breath rate led to a lower amount of trigger errors. Patient–ventilator asynchrony was not associated with prolonged duration of mechanical ventilation or paediatric intensive care stay.

Conclusions

The additional work-of-breathing caused by trigger errors in ventilated children can take up to 30–40% of the total work-of-breathing. Trigger errors were less common in patients breathing spontaneously and those able to generate higher pressure–time–product and pressure swings.

Trial registration

Not applicable.

Pneumatocele after Acute Respiratory Distress Syndrome in an Adult Patient: A Case Report

Pulmonary pneumatocele is a cystic, air-filled lesion in the lung parenchyma. It results from underlying inflammation or bronchial injury. It is seen in several lung pathologies including bacterial pneumonia, positive-pressure ventilation, chest trauma, chemical pneumonitis, and is most often seen in infants and children. On imaging, pneumatoceles appear as rounded, thin-walled, air-filled spaces in the lung parenchyma. The exact mechanism for forming pneumatoceles is not fully understood but thought to be due to a check-valve mechanism due to obstruction by inflammation causing air trapping in the damaged lung. These lesions are asymptomatic and transient in most patients and disappear by about 6 weeks. They usually do not require any specific treatment or intervention. Surgical intervention is only necessary when pneumatoceles cause cardiopulmonary compromise or rupture into the pleural space. We describe a case of a young adult who developed a pneumatocele after developing acute respiratory distress syndrome from community-acquired pneumonia treated with positive-pressure ventilation. He was managed conservatively with complete resolution of symptoms.

Absence seizure provocation during routine EEG: Does position of the child during hyperventilation affect the diagnostic yield?

PURPOSE

When performed correctly, hyperventilation (HV) for three minutes provokes absence seizures in virtually all children, a finding suggestive of a diagnosis of childhood absence epilepsy (CAE). Interestingly, some children experience absence seizures while performing HV in the office yet do not experience absences during HV on subsequent routine EEG. In most instances, HV during routine EEG is performed in the supine position, while in the office HV is done with the child sitting-up. Therefore, we hypothesized that the position in which HV is performed may influence its yield in provoking absence seizures.

METHODS

We conducted a randomized multi-center controlled trial among children (4-10 years old) with suspected CAE. During a routine EEG, children were asked to perform HV twice, in the supine and sitting positions.

RESULTS

Twenty children (four males) diagnosed with CAE were included in the analysis. Seventeen of the 20 patients experienced absence seizures while sitting and 13 experienced seizures during supine HV (p = 0.031). All patients that had absence seizures during supine HV also had seizures during sitting HV. Among patients with absences in both positions, seizure duration was significantly shorter during sitting HV (mean 8.69 seconds) than during supine HV (mean 12 seconds) (p = 0.042). An opposite tendency was seen in the younger age group (4-7 years), with shorter seizures in the supine HV group (5.6 seconds supine, 7.57 seconds sitting, p = 0.019).

CONCLUSIONS

HV in the sitting position may increase the yield of provoking absence seizures during routine EEGs, thereby improving its sensitivity in the diagnosis of CAE.

Accuracy of dynamic preload variables for predicting fluid responsiveness in patients with pediatric liver cirrhosis: A prospective study

BACKGROUND

We have previously reported that dynamic preload variables predicted fluid responsiveness in adult patients with liver cirrhosis. However, pediatric patients with cirrhosis may present with unique hemodynamic characteristics, and therefore, the predictive accuracy of these variables in such patients must be clarified.

AIMS

To investigate the accuracy of dynamic preload variables for predicting fluid responsiveness in pediatric patients with cirrhosis.

METHODS

A total of 27 pediatric patients with cirrhosis undergoing orthotopic liver transplantation were enrolled in this study. Patients' pulse pressure variation, stroke volume variation, stroke volume index, and central venous pressure were measured using the calibrated pulse contour cardiac output system. The plethysmographic variability index was measured using a Masimo Radical 7 co-oximeter. During the hepatic dissection phase of the surgery, repeated intraoperative fluid challenges with 10 mL kg^-1 of crystalloid within 15 minutes were administered. Fluid responsiveness was defined as an increase in stroke volume index of ≥15% after fluid challenge.

RESULTS

A total of 61 fluid challenges were administered resulting in 15 fluid responders and 46 fluid nonresponders. Fluid challenge induced significant decreases in all three dynamic preload variables but not in the fluid nonresponders. However, the area under the receiver operating characteristic curves for pulse pressure variation, stroke volume variation, plethysmographic variability index, and central venous pressure for predicting fluid responsiveness were 0.67 (95% confidence interval: 0.52-0.82; P = .0255), 0.68 (95% confidence interval: 0.54-0.83; P = .0140), 0.56 (95% confidence interval: 0.40-0.71; P = .4724), and 0.57 (95% confidence interval: 0.40-0.74; P = .4192), respectively.

CONCLUSIONS

Dynamic preload variables do not predict fluid responsiveness in pediatric patients with liver cirrhosis.

Laryngeal Constriction Phenomena in Infant Vocalizations

Purpose Instances of laryngeal constriction have been noted as a feature of infant vocal development. The purpose of this study was to directly evaluate the developmental occurrence of laryngeal constriction phenomena in infant crying, cooing, and babbling vocalizations. Method The cry and noncry vocalizations of 20 healthy term-born infants between the ages of 1 and 7 months were examined for instances of laryngeal constriction. Approximately 20,000 vocalization samples were acoustically evaluated, applying a combined visual (frequency spectra and melody curves) and auditory analysis; the occurrence of instances of different constriction phenomena was analyzed. Results Laryngeal constrictions were found during the production of cry and noncry vocalizations. The developmental pattern of constrictions for both vocalizations was charac-terized by an increase in constrictions followed by a decrease. During the age period of 3-5 months, when cry and noncry vocalizations were co-occurring, laryngeal constrictions were observed in 14%-22% of both types of vocalizations. An equal percentage of constrictions was found for both vocalizations at 5 months of age. Conclusions The findings confirm that the production of laryngeal constriction is a regularly occurring phenomenon in healthy, normally developing infants' spontaneous crying, cooing, and marginal babbling. The occurrence of constriction in both cry and noncry vocalizations suggests that an infant is exploiting physiological constraints of the sound-generating system for articulatory development during vocal exploration. These results lend support to the notion that the laryngeal articulator is the principal articulator that infants 1st start to control as they test and practice their phonetic production skills from birth through the 1st several months of life.

Surrogate indices of aortic peak systolic velocity variation to monitor fluid responsiveness in pediatric non-cardiac surgery: a prospective observational study

Aortic peak systolic velocity variation (ΔV_peakAo) is a reliable dynamic indicator of preload in mechanically ventilated children. However, easily measurable alternative parameters like carotid peak systolic velocity variation (ΔV_peakCa) and suprasternal peak systolic velocity variation (ΔV_peakSs) are not well evaluated in children. The aim of the study was to find correlation between ΔV_peakCa and ΔV_peakSs to ΔV_peakAo, as potential surrogate markers of fluid responsiveness. 52 children, 1-12 years old, undergoing major non-cardiac surgeries under general endotracheal anaesthesia were recruited for this single-centre prospective observational study. ΔV_peakAo, ΔV_peakCa and ΔV_peakSs were measured by pulsed wave Doppler in appropriate windows, measuring maximum and minimum peak flow velocity over a single respiratory cycle. Calculated parameters were compared by a repeated measures study design. Correlation coefficients were 0.82 between ΔV_peakAo and ΔV_peakSs and 0.73 between ΔV_peakAo and ΔV_peakCa. Bland-Altman analysis showed minimal bias of 1.86 percentage points with limits of agreement of 11.21 to - 7.49 (ΔV_peakAo and ΔV_peakSs) and 3.93 percentage points with limits of agreement of 14.04 to - 6.18 (ΔV_peakAo and ΔV_peakCa). ΔV_peakSs and ΔV_peakCa also showed good discrimination to predict ΔV_peakAo (lying in previously validated fluid responsive zones) with sensitivities and specificities of 82.25% and 85% with cut-off of 11% for ΔV_peakSs, and 88.52% and 70% with cut-off of 8.6% for ΔV_peakCa. Carotid peak systolic velocity variation (ΔV_peakCa) and suprasternal peak systolic velocity variation (ΔV_peakCa) can be potential surrogate markers for Aortic peak systolic velocity variation (ΔV_peakAo) in assessing fluid responsiveness in mechanically ventilated children.Study registration: Clinicaltrials.gov ID NCT03155555.

Equilibration Time Required for Respiratory System Compliance and Oxygenation Response Following Changes in Positive End-Expiratory Pressure in Mechanically Ventilated Children

OBJECTIVES

Increases in positive end-expiratory pressure are implemented to improve oxygenation through the recruitment and stabilization of collapsed alveoli. However, the time it takes for a positive end-expiratory pressure change to have maximum effect upon oxygenation and pulmonary compliance has not been adequately described in children. Therefore, we sought to quantify the time required for oxygenation and pulmonary system compliance changes in children requiring mechanical ventilation.

DESIGN

Retrospective analysis of continuous data.

SETTINGS

Multidisciplinary ICU of a pediatric university hospital.

PATIENTS

Mechanically ventilated pediatric subjects.

INTERVENTIONS

A case was eligible for analysis if during a 90-minute window following an increase in positive end-expiratory pressure, no other changes to the ventilator were made, ventilator and physiologic data were continuously available and a positive oxygenation response was observed. Time to 90% (T90) of the maximum change in oxygenation and compliance was computed. Differences between oxygenation and compliance T90 were compared using a paired t test. The effect of severity of illness (by oxygen saturation index) upon oxygenation and compliance was analyzed.

MEASUREMENTS AND MAIN RESULTS

A total of 200 subjects were enrolled and 1,150 positive end-expiratory pressure change cases were analyzed. Of these, 54 subjects with 171 positive end-expiratory pressure change case were included in the analysis (67% were responders).Changes in dynamic compliance (T90 = 38 min) preceded changes in oxygenation (T90 = 71 min; p < 0.001). Oxygenation response differed depending on severity of illness quantified by oxygen saturation index; lung dysfunction was associated with a longer response time (p = 0.001).

CONCLUSIONS

T90 requires 38 and 71 minutes for dynamic pulmonary compliance and oxygenation, respectively; the latter was directly observed to be dependent upon severity of illness. To our knowledge, this is the first report of oxygenation and compliance equilibration data following positive end-expiratory pressure increases in pediatric mechanically ventilated subjects.

Cardiac and lung point-of-care ultrasound in pediatric anesthesia and critical care medicine: Uses, pitfalls, and future directions to optimize pediatric care

Point-of-care ultrasound (POCUS) has found many relevant applications in pediatric anesthesia and critical care medicine. Specifically, the cardiac and pulmonary POCUS examinations provide a wealth of information from physical examination assistance to diagnostic evaluation and assessment of treatment response. However, as with any adjunct, potentially dangerous pitfalls exist when POCUS is performed, interpreted, and applied by the novice sonographer. Using case illustrations, we highlight the clinical application of POCUS in addition to potential dangers. Additionally, suggestions for learning POCUS, assessing competency and credentialing are reviewed.

Getting to know a familiar face: Current and emerging focused ultrasound applications for the perioperative setting

Ultrasound technology is available in many pediatric perioperative settings. There is an increasing number of ultrasound applications for anesthesiologists which may enhance clinical performance, procedural safety, and patient outcomes. This review highlights the literature and experience supporting focused ultrasound applications in the pediatric perioperative setting across varied disciplines including anesthesiology. The review also suggests strategies for building educational and infrastructural systems to translate this technology into clinical practice.

Cardiopulmonary Bypass in Premature and Low Birth Weight Neonates - Implications for Postoperative Care From a Neonatologist/Intensivist Perspective

Prematurity and low weight remain significant risk factors for mortality after neonatal cardiac surgery despite steady gains in survival. Newer and lower weight thresholds for operability are constantly generated as surgeons gather proficiency, technical mastery, and experience in performing complex procedures on extremely small infants. Relationship between birth weight and survival after cardiac surgery is nonlinear with 2 kg being an inflection point below which marked decline in survival occurs. If strides toward improved survival in this weight category are to be made, understanding the inherent vulnerabilities of the premature and low birth weight infant is important in addition to acknowledging the vulnerabilities of the system in which care is delivered.

Polysomnography Reference Values in Healthy Newborns

STUDY OBJECTIVES

Polysomnography (PSG) is increasingly used in the assessment of infants. Newborn PSG reference values based on recent standardization are not available. This study provides reference values for PSG variables in healthy newborn infants.

METHODS

Cross-sectional study of normal term newborn infants using standardized PSG collection and American Academy of Sleep Medicine interpretation criteria.

RESULTS

Thirty infants born between 37 and 42 weeks gestation underwent PSG testing before 30 days of age (mean 19.6 days). The infants had a mean sleep efficiency of 71% with average proportions of transitional, NREM and REM sleep estimated at 16.1%, 43.3% and 40.6% respectively. Mean arousal index was 14.7 events/h with respiratory arousal index of 1.2 events/h. Mean apnea-hypopnea index (AHI) was 14.9 events/h. Central, obstructive, and mixed apnea indices were 5.4, 2.3, and 1.2 events/h respectively. Mean oxygen saturation in sleep was 97.9% with a nadir of 84.4%. Mean end tidal CO₂ was 35.4 mmHg with an average of 6.2% of sleep time spent above end-tidal CO₂ 45 mmHg and 0.6% above 50 mmHg.

CONCLUSIONS

The sleep efficiency was significantly lower and the AHI was significantly higher compared to healthy children older than 1 year. The AHI was also higher than reported in healthy infants older than 1 month. These findings suggest current severity classifications of sleep apnea may not apply to newborn infants.