Respiratory muscle performance in infants and children

Unraveling belly dancer's dyskinesia and other puzzling diagnostic contortions: A narrative literature review

Belly dancer's dyskinesia (BDD) is characterized by involuntary abdominal wall movements that are rhythmic, repetitive, and dyskinetic. The present study aims to review BDD's etiology, pathophysiology, and management. We searched six databases to locate existing reports on BDD published from 1990 to October 2023 in electronic form. A total of 47 articles containing 59 cases were found. The majority of the patients affected by BDD were female, accounting for 61.01% (36/59) of the cases. The mean and median ages were 49.8 (standard deviation: 21.85) and 52 years (range: 7-85), respectively. The BDD was unilateral in only 3.38% (2/59). The most commonly reported causes associated with BDD were 17 idiopathic, 11 drug-induced, 11 postsurgical procedures, 5 pregnancies, and 4 Vitamin B12 deficiencies. BDD is a diagnosis of exclusion, and other more common pathologies with similar presentation should be ruled out initially. Differential diagnostic reasoning should include diaphragmatic myoclonus, cardiac conditions, truncal dystonia, abdominal motor seizures, propriospinal myoclonus, and functional or psychiatric disorders.

Efficacy of prophylactic high-flow nasal cannula therapy for postoperative pulmonary complications after pediatric cardiac surgery: a prospective single-arm study

PURPOSE

This study investigated the incidence of postoperative pulmonary complications (PPC) when high-flow nasal cannula therapy (HFNC) is used prophylactically after pediatric cardiac surgery, and evaluated its efficacy.

METHODS

This was a single-arm prospective interventional study that was conducted in a tertiary teaching hospital with eight beds in the pediatric cardiac ICU after approval by the Ethics Committee. One-hundred children under the age of 48 months who were scheduled for cardiac surgery for congenital heart disease were recruited. HFNC was used for 24 h after extubation at a 2 L/kg/min flow rate. The primary outcome was the incidence of PPC within 48 h after extubation. PPC was defined as atelectasis and acute respiratory failure meeting certain criteria. We considered prophylactic HFNC as effective if the prevalence of PPC was < 10%, based on previous reports of reintubation rates of 6%-9% after pediatric cardiac surgery.

RESULTS

A total of 91 patients were finally included in the analysis. The incidence of PPC within 48 h after extubation was 18.7%, whereas atelectasis was observed in 13.2%, and acute respiratory failure in 8.8%. Reintubation rate within 48 h after extubation was 0%.

CONCLUSIONS

We found the incidence of PPC with prophylactic HFNC after planned extubation after pediatric cardiac surgery. However, the incidence was > 10%; therefore, we could not demonstrate its efficacy in this single-arm study. Further studies are needed to investigate whether the HFNC could be adapted as first-line oxygen therapy after pediatric cardiac surgery.

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.

Role of Lung Ultrasound in the Detection of Postoperative Pulmonary Complications in Pediatric Patients: A Prospective Observational Study

OBJECTIVE

To evaluate the incremental benefit of lung ultrasound (LUS) over clinical examination and chest x-rays (CXR) together (clinico-radiologic examination) for the diagnosis of postoperative pulmonary complications (PPC).

DESIGN

Prospective observational study.

SETTING

Tertiary care center.

PARTICIPANTS

One hundred children after corrective congenital cardiac surgery with left-to-right shunts.

INTERVENTION

Participants were independently evaluated with clinico-radiologic examination by the treating team, as well as LUS by an investigator at 12, 24, 48, and 72 hours after surgery. After recording the diagnoses, the LUS findings were disclosed to the treating team and a final diagnosis was made. CXR scores and LUS scores were evaluated for their ability to predict PPC.

MEASUREMENTS AND MAIN RESULTS

A total of 34 cases of PPCs were observed. Of these, 32 each were detected by clinico-radiologic examination and LUS alone. Addition of LUS improved total number of PPCs detected in the early postoperative period but not in the late postoperative period. Preoperative and early postoperative LUS scores were superior to CXR scores in predicting occurrence of PPC (area under receiver operating characteristics curve [AUROC] 0.920 v 0.732; p < 0.001 preoperatively; AUROC 0.987 v 0.858, p = 0.001 at 12 hours postoperatively). Multivariate analysis suggested LUS score as an independent predictor of PPC, and LUS score along with aortic cross-clamp time as independent predictors of duration of mechanical ventilation and intensive care unit stay.

CONCLUSIONS

LUS improves identification of PPC over clinico-radiologic examination in the early postoperative period. Preoperative LUS scores have better predictive ability than CXR scores for the occurrence of PPC.

Association of tidal volume during mechanical ventilation with postoperative pulmonary complications in pediatric patients undergoing major scoliosis surgery

BACKGROUND

The use of lung-protective ventilation strategies with low tidal volumes may reduce the occurrence of postoperative pulmonary complications. However, evidence of the association of intraoperative tidal volume settings with pulmonary complications in pediatric patients undergoing major spinal surgery is insufficient.

AIMS

This study examined whether postoperative pulmonary complications were related to tidal volume in this population and, if so, what factors affected the association.

METHODS

In this retrospective cohort study, data from pediatric patients (<18 years old) who underwent posterior spinal fusion between 2016 and 2018 were collected from the hospital electronic medical record. The associations between tidal volume and the clinical outcomes were examined by multivariate logistic regression and stratified analysis.

RESULTS

Postoperative pulmonary complications occurred in 41 (16.1%) of 254 patients who met the inclusion criteria. For the entire cohort, tidal volume was associated with an elevated risk of pulmonary complications (adjusted odds ratio [OR] per 1 mL/kg ideal body weight [IBW] increase in tidal volume, 1.28; 95% confidence interval [CI], 1.01-1.63, P = .038). In subgroup analysis, tidal volume was associated with an increased risk of pulmonary complications in patients older than 3 years (adjusted OR per 1 mL/kg IBW increase in tidal volume, 1.43, 95% CI: 1.12-1.84), but not in patients aged 3 years or younger (adjusted OR, 0.78, 95% CI: 0.46-1.35), indicating a significant age interaction (P = .035).

CONCLUSION

In pediatric patients undergoing major spinal surgery, high tidal volume was associated with an elevated risk of postoperative pulmonary complications. However, the effect of tidal volume on pulmonary outcomes in the young subgroup (≤3 years) differed from that in the old (>3 years). Such information may help to optimize ventilation strategy for children of different ages.

Falha de extubação em unidade de terapia intensiva pediátrica: estudo de coorte retrospectivo

RESUMO Na unidade de terapia intensiva (UTI) pediátrica, a falha de extubação pode aumentar o risco de mortalidade. Este estudo objetivou: (1) verificar a taxa de falha de extubação na UTI pediátrica de um hospital público do município de Bauru (São Paulo, Brasil); (2) identificar a principal causa atribuída à falha de extubação; (3) avaliar se características como a idade e o tempo de ventilação mecânica invasiva (VMI) estão associadas à falha de extubação; (4) avaliar se o tempo de permanência na UTI e hospital é maior entre os pacientes que apresentaram falha de extubação. Foi realizado estudo de coorte retrospectivo com 89 pacientes internados de maio de 2017 até julho de 2018. Os resultados mostraram taxa de falha de extubação correspondente a 16%. A principal causa atribuída à falha de extubação foi o estridor laríngeo, totalizando 57% dos casos. A comparação intergrupos (sucesso vs. falha de extubação) não mostrou diferenças em relação à idade (p=0,294) e ao tempo de VMI (p=0,228). No entanto, observamos que o grupo falha de extubação apresentou maior tempo de UTI (p=0,000) e hospital (p=0,010). Desta forma, concluímos que a taxa de extubação está de acordo com a observada em outros estudos. O estridor laríngeo foi responsável por mais da metade dos casos de falha de extubação. Embora a idade e o tempo de VMI não tenham sido características associadas à falha de extubação, esta contribuiu para o maior período de permanência na UTI e no hospital.

Critical Heart Failure and Shock

OBJECTIVES

The objectives of this review are to discuss the clinical assessment, pathophysiology, and management of shock, with an emphasis on circulatory physiology, cardiopulmonary interactions, and pharmacologic strategies to optimize systemic oxygen delivery. These principles will then be applied to the clinical syndromes of heart failure and cardiogenic shock that are seen in children.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSION

An understanding of essential circulatory physiology and the pathophysiology of shock are necessary for managing patients at risk for or in a state of shock. A timely and accurate assessment of cardiac function, cardiac output, and tissue oxygenation and the means by which to enhance the relationship between oxygen delivery and consumption are essential in order to optimize outcomes.

Comorbid Conditions in Neonates With Congenital Heart Disease

OBJECTIVES

The objectives of this review are to discuss the pathophysiology, clinical impact and treatment of major noncardiac anomalies, and prematurity in infants with congenital heart disease.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

Mortality risk is significantly higher in patients with congenital heart disease and associated anomalies compared with those in whom the heart defect occurs in isolation. Although most noncardiac structural anomalies do not require surgery in the neonatal period, several require surgery for survival. Management of such infants poses multiple challenges. Premature infants with congenital heart disease face challenges imposed by their immature organ systems, which are susceptible to injury or altered function by congenital heart disease and abnormal circulatory physiology independent of congenital heart disease. For optimal outcomes in premature infants or in infants with multiple congenital anomalies, a collaborative interdisciplinary approach is necessary.

Respiratory muscle strength in healthy infants and those with surgically correctable anomalies

Assessment of respiratory muscle strength provides important diagnostic and prognostic information. Normative data in healthy, term infants is, however, limited. Surgically correctable birth defects, congenital diaphragmatic hernia (CDH) and abdominal wall defects (AWD), commonly have impaired diaphragm function. The study aims were to obtain normative data for respiratory muscle strength in healthy, term born infants at birth and at 6 weeks postnatal age (PNA) and to investigate the influence of growth and maturation on inspiratory muscle strength in CDH/AWD infants. Maximal inspiratory (cPimax) and expiratory (cPemax) pressures during crying were measured at birth in 67 healthy, term born infants (mean (SD) gestational age (GA) 39.4 (1.7) weeks) and reassessed in 27 at 6 weeks PNA. cPimax and functional residual capacity (FRC) (22.3 (4.2) ml/kg) were also measured in 23 infants with AWD/CDH (mean (SD) GA 36.9 (2.1) weeks) and reassessed in 16 at median (range) 6.5 (1.5-15) months PNA. In healthy infants, mean (SD) cPimax was 88.8 (19.33) cmH2 O and cPemax 61.8 (13.5) cmH2 O at birth, increasing significantly at followup to 100.9 (15.2) cmH2 O (P < 0.05) and 82.6 (19.4) cmH2 O (P < 0.001) respectively. Mean (SD) cPimax was significantly lower (47.5 (22.4) cmH2 O, P < 0.0001) in AWD/CDH infants compared to healthy infants at birth but had increased significantly to 88.1 (27.6) cmH2 O (P < 0.0001) at followup which correlated significantly with increases in FRC (r(2)  = 0.33, P = 0.0263). Infants with AWD and CDH have significantly reduced inspiratory muscle strength compared to healthy term born infants but strength increases markedly in early life.

Management of the postoperative pediatric cardiac surgical patient

OBJECTIVE

To review the salient aspects and latest advances in the management of the postoperative pediatric cardiac patient.

DATA SOURCE

A Medline-based literature source.

CONCLUSION

The practice of pediatric cardiac intensive care has evolved considerably over the last several years. These efforts are the result of a collaborative effort from all subspecialties involved in the care of pediatric patients with congenital heart disease. Discoveries and innovations that are representative of this effort include the extension of cerebral oximetry from the operating room into the critical care setting; mechanical circulatory devices designed for pediatric patients; and surgery in very low birth weight neonates. Advances such as these impact postoperative management and make the field of pediatric cardiac intensive care an exciting, demanding, and evolving discipline, necessitating the ongoing commitment of various disciplines to pursue a greater understanding of disease processes and how to best go about treating them.

Critical diaphragm failure in sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the leading cause of death in infants between the ages of 1 and 12 months in developed countries. SIDS is by definition a diagnosis of exclusion, and its mechanism of action is unknown. The SIDS-Critical Diaphragm Failure (CDF) hypothesis postulates that the cause of death in SIDS is respiratory failure caused by CDF. Four principal risk factors contribute to CDF in young infants: undeveloped respiratory muscles, non-lethal infections, prone resting position, and REM sleep. Even relatively minor infections can cause an acute and significant reduction in diaphragm force generation capacity that in conjunction with other risk factors can precipitate CDF. CDF-induced acute muscle weakness leaves few, if any pathological marks on the affected tissue.Understanding the underlying mechanism of SIDS may help in formulating new approaches to child care that can help to further reduce the incidence of SIDS.

Influence of maturation on infant diaphragm function assessed by magnetic stimulation of phrenic nerves

Infant diaphragm function may be adversely affected in a variety of disorders and conditions. Key to establishing an accurate diagnosis are appropriate control data. The aim of this study was to determine the effect of maturation on diaphragm function, using a nonvolitional test. Diaphragm function was assessed by measuring the transdiaphragmatic pressure (Pdi) generated by magnetic stimulation of the phrenic nerves. Ballon catheters were positioned in the lower third of the esophagus and stomach. Esophageal (Pes) and gastric (Pgas) pressure changes were measured using differential pressure transducers. The pressure signals were amplified and displayed in real time on a computer (running Labview trade mark software) and Pdi derived by online subtraction of Pes from Pgas. Twenty-nine infants (14 born preterm), at a median gestational age of 37 (range, 25-42) weeks, were studied at a median postconceptional age (PCA) of 39 (range, 32-44) weeks. At time of measurement, none had respiratory problems or were hyperinflated (functional residual capacity ranged from 23-35 mL/kg). The preterm infants had significantly lower transdiaphragmatic pressures responses following median left (4.0, range 2.5-6.8 cmH(2)O vs. 4.8, range 2.8-7.2 cmH(2)O) and median right phrenic nerve stimulation (3.6, range 2.6-4.8 cmH(2)O vs. 4.3, range 2.7-6.8 cmH(2)O) (P < 0.05) than term infants. Following left and right phrenic nerve stimulation, Pdi correlated significantly with gestational age (r = 0.4, P < 0.05, and r = 0.4, P < 0.05, respectively) and PCA (r = 0.37, P = 0.05, and r = 0.56, P < 0.01, respectively). We conclude that gestational age at birth and postconceptional age at time of measurements must be taken into account when interpreting the results of infant diaphragm function tests.

Diaphragm dimensions of the healthy preterm infant

BACKGROUND

The diaphragm is the major inspiratory muscle in the neonate; however, human neonatal diaphragm development has not been extensively studied. We hypothesized that diaphragm thickness (t(di)) would be positively related to postmenstrual age (PMA), body weight, body length, head circumference, and nutritional intake.

OBJECTIVES

To evaluate the evolution of diaphragm growth and motion in the healthy, preterm infant.

METHODS

We used ultrasound to measure t(di) at the zone of apposition to the rib cage and diaphragm excursion (e(di)) during inspiration. Thirty-four stable, preterm infants (16 males and 18 females) between 26 and 37 weeks' PMA were studied during quiet sleep at weekly intervals until the time of discharge or transfer from the neonatal intensive care unit. All infants were clinically stable and not receiving ventilatory support.

RESULTS

We found that 1) t(di) increased from 1.2 +/- 0.1 to 1.7 +/- 0.05 mm between 26 to 28 and 35 to 37 weeks' PMA; 2) t(di) was positively correlated with PMA (r = 0.40), body weight (r = 0.52), body length (r = 0.53), and head circumference (0.49), but not with postnatal nutritional intake (r = 0.09); and 3) e(di) decreased with increasing PMA.

CONCLUSIONS

Our findings suggest that diaphragm development in premature infants scales with body dimensions. We speculate that the increase in t(di) with age is likely attributable to increased diaphragm muscle mass, and the reduced e(di) with age may be resulting from a reduction in chest wall compliance.

Effect of maturity on maximal transdiaphragmatic pressure in infants during crying

The aim of this study was to determine the effect of maturation on diaphragmatic function. In addition, we investigated whether noninvasive assessment yielded similar results to invasive measurement. Twenty-eight infants, median gestational age (GA) 35.5 wk (range, 25 to 42 wk) and postconceptional age (PCA), 37.6 wk (range, 32 to 44 wk), were examined. Diaphragmatic function was assessed by measuring the maximal transdiaphragmatic pressure during crying (cPdi) using balloon catheters in the midesophagus (Pes) and the stomach (Pgas). In 14 of the infants, a noninvasive measurement of inspiratory muscle strength, maximal inspiratory pressure (PImax), was also made. cPdi and PImax were recorded during a crying effort with the airway occluded at end-expiration. The median cPdi and Pes during crying (cPes), but not Pgas during crying (cPgas), were significantly lower in those studied at a PCA of less than term compared with those studied at an older age (p < 0.05). cPdi and cPes, but not cPgas, correlated significantly with PCA (r = 0.44, p < 0.02; r = 0.43, p < 0.03; respectively) and gestational age (r = 0.46, p < 0.02 and r = 0.56, p < 0.01; respectively). In the 14 infants, the median PImax was lower, but it correlated significantly with cPdi (r = 0.79, p < 0.01). We conclude maturation does affect diaphragm function, and PImax may provide a noninvasive index of diaphragm strength.

Changes in pulmonary hyperinflation and bronchial hyperresponsiveness following treatment with lansoprazole in children with cystic fibrosis

SUMMARY. In this prospective open study of 14 children with cystic fibrosis (CF), we evaluated the effect of 1 year adjuvant therapy with lansoprazole, a proton pump inhibitor (PPI), on growth, fecal fat loss, body composition and lung function. Only stable patients with pancreatic insufficiency were included, and their data were compared to those of a large Dutch pediatric normal reference population. During the use of the PPI, mean weight and height did not change significantly, while body mass index improved (P < 0.05). An immediate significant and persistent reduction of fecal acid steatocrit (P < 0.05) was demonstrated. Compared to normal Dutch children, the CF patients showed significantly decreased standard deviation scores (SDS) for total body fat (TBF, -0.966) and fat-free mass (FFM, -1.826). Under lansoprazole, TBF improved significantly (P < 0.05), while mean FFM remained unchanged. A significant improvement in total lung capacity (P < 0.05), residual volume (P = 0.055), and maximal inspiratory mouth pressure (P = 0.002) was also demonstrated. Hyperinflation tended to decrease during the use of a PPI. Daily recordings of peak expiratory flow (PEF) showed a maximal diurnal variability of 28% of recent best PEF and minimal morning PEF of 72% of recent best PEF, confirming that bronchial hyperresponsiveness is increased in CF. We conclude that adjuvant therapy with lansoprazole in young CF patients with persistent fat malabsorption, decreased fat losses and improved total body fat. Lung hyperinflation decreased, which may partly explain the improvement in inspiratory muscle performance. The simultaneous improvements in body composition and lung hyperinflation suggest a relationship between these two parameters. Further research is necessary to confirm such a relationship and to elucidate the mechanisms involved.

Maximal airway pressures during crying in healthy preterm and term neonates

Respiratory muscle strength can be assessed by measurement of maximal inspiratory (PIMAX) and maximal expiratory pressure (P(EMAX)) during crying. There are, however, relatively few data on P(IMAX) and P(EMAX) in infancy, particularly from those born preterm. Our aim was to investigate which factors influenced P(IMAX) and P(EMAX) in preterm and term infants. Forty infants, median gestational age 37 weeks (range 26-43) and birthweight 2.579 kg (range 0.956-5.180) were studied at a postconceptional age (PCA) of 38 weeks (range 32-44). None had respiratory problems. A facemask was placed firmly over the infant's mouth and nose and the infant studied during spontaneous crying. A pneumotachograph fitted snugly into the facemask and from a sideport airway pressure changes were measured. During crying, the distal end of the pneumotachograph was occluded for five breaths and at least three separate occlusions were made. The highest P(EMAX) value sustained for at least 1 s and the highest peak inspiratory pressure P(IMAX) were recorded. The mean P(IMAX) and P(EMAX) were higher in the term compared to the preterm infants (70 cmH2O +/-S.D. 19 versus 58 cmH2O +/-S.D. 17 P(IMAX) and 53 cmH2O +/-S.D. 13 versus 44 cmH2O +/-S.D. 19 P(EMAX), P< 0.05). Both P(IMAX) and P(EMAX) related significantly with postconceptional age, gestational age and weight, but not postnatal age. Stepwise regression analysis demonstrated P(IMAX) related independently with PCA and P(EMAX) with weight. These results suggest respiratory muscle strength is influenced by maturation at birth.

Does continuous positive airway pressure (CPAP) during weaning from intermittent mandatory ventilation in very low birth weight infants have risks or benefits? A controlled trial

OBJECTIVE

The purpose of this study was to evaluate three ventilator weaning strategies and to evaluate whether the use of continuous positive airway pressure (CPAP) via a nasopharyngeal or endotracheal tube would increase the likelihood of extubation failure in very low birth weight (VLBW) infants.

STUDY DESIGN

We studied prospectively 87 preterm infants (mean +/- SD; birth weight: 1078 +/- 188 g; gestational age: 28.8 +/- 2.2 weeks) who were in the process of being weaned from intermittent mandatory ventilation (IMV). Infants were assigned by systematic sampling to one of the following three treatment groups: (1) direct extubation from IMV (D.EXT) (n = 30); (2) preextubation endotracheal CPAP (ET-CPAP) for 12-24 hr (n = 28); or (3) postextubation nasopharyngeal CPAP (NP-CPAP) for 12-24 hr (n = 29). Failure was defined as the need for resumption of mechanical ventilation within 72 hr of extubation due to frequent or severe apnea and/or respiratory failure (pH < 7.25, PaCO2 > 60 mm Hg, and/or requirement for oxygen FiO2 > 60%).

RESULTS

There were no significant differences in failure rates among the three procedures. Failures were 2/30 (7%) in D.EXT; 4/28 (14%) in ET-CPAP; and 7/29 (24%) in the NP-CPAP. There were also no differences in FiO2, PaO2, and respiratory rates before and after discontinuation of IMV among the three groups. PaCO2 values were slightly higher in the NP-CPAP group 12-24 hr after weaning from IMV.

CONCLUSION

We were unable to demonstrate a clear difference in extubation outcome by use of CPAP administered via an endotracheal or nasopharyngeal tube when compared to direct extubation from low-rate IMV in VLBW infants.

Prolonged mechanical ventilation in children

Improvements in neonatal and pediatric intensive care have produced a growing population of children dependent on mechanical ventilation for survival. Long-term mechanical ventilation has become a realistic alternative to death from progressive respiratory failure for many children with chronic respiratory illness. This article reviews the pathophysiology, etiology, and management of chronic respiratory failure in childhood.