Iron Deficiency in Anemic Children Surviving Critical Illness: Post Hoc Analysis of a Single-Center Prospective Cohort in Canada, 2019-2022

OBJECTIVES

Many children leave the PICU with anemia. The mechanisms of post-PICU anemia are poorly investigated, and treatment of anemia, other than blood, is rarely started during PICU. We aimed to characterize the contributions of iron depletion (ID) and/or inflammation in the development of post-PICU anemia and to explore the utility of hepcidin (a novel iron marker) at detecting ID during inflammation.

DESIGN

Post hoc analysis of a single-center prospective study (November 2019 to September 2022).

SETTING

PICU, quaternary center, Canada.

PATIENTS

Children admitted to PICU with greater than or equal to 48 hours of invasive or greater than or equal to 96 hours of noninvasive ventilation. We excluded patients with preexisting conditions causing anemia or those admitted after cardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hematological and iron profiles were performed at PICU discharge on 56 participants of which 37 (37/56) were diagnosed with anemia. Thirty-three children (33/56; 59%) were younger than 2 years. Median Pediatric Logistic Organ Dysfunction score was 11 (interquartile range, 6-16). Twenty-four of the 37 anemic patients had repeat bloodwork 2 months post-PICU. Of those, four (4/24; 16%) remained anemic. Hematologic profiles were categorized as: anemia of inflammation (AI), iron deficiency anemia (IDA), IDA with inflammation, and ID (low iron stores without anemia). Seven (7/47; 15%) had AI at discharge, and one had persistent AI post-PICU. Three patients (3/47; 6%) had IDA at discharge; of which one was lost to follow-up and the other two were no longer anemic but had ID post-PICU. Eleven additional patients developed ID post-PICU. In the exploratory analysis, we identified a diagnostic cutoff value for ID during inflammation from the receiver operating characteristic curve for hepcidin of 31.9 pg/mL. This cutoff would increase the detection of ID at discharge from 6% to 34%.

CONCLUSIONS

The burden of ID in children post-PICU is high and better management strategies are required. Hepcidin may increase the diagnostic yield of ID in patients with inflammation.

Two months outcomes following delirium in the pediatric intensive care unit

The lasting consequences of delirium in children are not well characterized. This study aimed to compare the two-month outcomes in pediatric intensive care unit (PICU) survivors according to the presence of delirium. Post-hoc analysis of a single-center prospective study of mechanically ventilated (invasive ventilation or non-invasive ventilation) children followed at the CHU Sainte-Justine PICU follow-up clinic two months after PICU discharge, between October 2018 and August 2022. Delirium was defined as one or more Cornell Assessment of Pediatric Delirium (CAPD) scores ≥ 9. Primary outcome was survivors' quality of life and secondary outcomes were sleep and posttraumatic stress and anxiety and depression in parents. Multivariable linear and logistic regression models assessed the independent associations between delirium and outcomes while adjusting for age, sex, comorbidity, diagnosis, severity of illness, PICU length of stay, and invasive mechanical ventilation. Of the 179 children included over a 47 month-period, 117 (65.4%) had delirium. Children with delirium were more commonly intubated (91.5% vs. 30.7%, p < 0.001) and had higher PELOD-2 scores (10 vs. 4, p < 0.001). On multivariable analysis, delirium was associated with a decreased quality of life at 2.3 months post discharge (p = 0.03). The severity of the delirium episode (higher scores of CAPD) was associated with a higher likelihood of sleep disturbances (OR 1.13, p = 0.01) and parental anxiety (OR 1.16, p = 0.01), in addition to lower quality of life (p = 0.03).Conclusions: Two months following their PICU stay, children with delirium had a lower quality of life, suggesting a lasting effect of delirium on children and their families.

Safety of primary nasotracheal intubation in the pediatric intensive care unit (PICU)

Background

Nasal tracheal intubation (TI) represents a minority of all TI in the pediatric intensive care unit (PICU). The risks and benefits of nasal TI are not well quantified. As such, safety and descriptive data regarding this practice are warranted.

Methods

We evaluated the association between TI route and safety outcomes in a prospectively collected quality improvement database (National Emergency Airway Registry for Children: NEAR4KIDS) from 2013 to 2020. The primary outcome was severe desaturation (SpO2 > 20% from baseline) and/or severe adverse TI-associated events (TIAEs), using NEAR4KIDS definitions. To balance patient, provider, and practice covariates, we utilized propensity score (PS) matching to compare the outcomes of nasal vs. oral TI.

Results

A total of 22,741 TIs [nasal 870 (3.8%), oral 21,871 (96.2%)] were reported from 60 PICUs. Infants were represented in higher proportion in the nasal TI than the oral TI (75.9%, vs 46.2%), as well as children with cardiac conditions (46.9% vs. 14.4%), both p < 0.001. Severe desaturation or severe TIAE occurred in 23.7% of nasal and 22.5% of oral TI (non-adjusted p = 0.408). With PS matching, the prevalence of severe desaturation and or severe adverse TIAEs was 23.6% of nasal vs. 19.8% of oral TI (absolute difference 3.8%, 95% confidence interval (CI): - 0.07, 7.7%), p = 0.055. First attempt success rate was 72.1% of nasal TI versus 69.2% of oral TI, p = 0.072. With PS matching, the success rate was not different between two groups (nasal 72.2% vs. oral 71.5%, p = 0.759).

Conclusion

In this large international prospective cohort study, the risk of severe peri-intubation complications was not significantly higher. Nasal TI is used in a minority of TI in PICUs, with substantial differences in patient, provider, and practice compared to oral TI.A prospective multicenter trial may be warranted to address the potential selection bias and to confirm the safety of nasal TI.

Ketamine Use in the Intubation of Critically Ill Children with Neurological Indications: A Multicenter Retrospective Analysis

BACKGROUND

Ketamine has traditionally been avoided for tracheal intubations (TIs) in patients with acute neurological conditions. We evaluate its current usage pattern in these patients and any associated adverse events.

METHODS

We conducted a retrospective observational cohort study of critically ill children undergoing TI for neurological indications in 53 international pediatric intensive care units and emergency departments. We screened all intubations from 2014 to 2020 entered into the multicenter National Emergency Airway Registry for Children (NEAR4KIDS) registry database. Patients were included if they were under the age of 18 years and underwent TI for a primary neurological indication. Usage patterns and reported periprocedural composite adverse outcomes (hypoxemia < 80%, hypotension/hypertension, cardiac arrest, and dysrhythmia) were noted.

RESULTS

Of 21,562 TIs, 2,073 (9.6%) were performed for a primary neurological indication, including 190 for traumatic brain injury/trauma. Patients received ketamine in 495 TIs (23.9%), which increased from 10% in 2014 to 41% in 2020 (p < 0.001). Ketamine use was associated with a coindication of respiratory failure, difficult airway history, and use of vagolytic agents, apneic oxygenation, and video laryngoscopy. Composite adverse outcomes were reported in 289 (13.9%) Tis and were more common in the ketamine group (17.0% vs. 13.0%, p = 0.026). After adjusting for location, patient age and codiagnoses, the presence of respiratory failure and shock, difficult airway history, provider demographics, intubating device, and the use of apneic oxygenation, vagolytic agents, and neuromuscular blockade, ketamine use was not significantly associated with increased composite adverse outcomes (adjusted odds ratio 1.34, 95% confidence interval CI 0.99-1.81, p = 0.057). This paucity of association remained even when only neurotrauma intubations were considered (10.6% vs. 7.7%, p = 0.528).

CONCLUSIONS

This retrospective cohort study did not demonstrate an association between procedural ketamine use and increased risk of peri-intubation hypoxemia and hemodynamic instability in patients intubated for neurological indications.

Outcomes of patients supported by mechanical ventilation and their families two months after discharge from pediatric intensive care unit

Introduction

The outcomes of children undergoing mechanical ventilation (MV) in a Pediatric Intensive Care Unit (PICU) remain poorly characterized and increasing knowledge in this area may lead to strategies that improve care. In this study, we reported the outcomes of children receiving invasive mechanical ventilation (IMV) and/or non-invasive ventilation (NIV), 2 months after PICU discharge.

Methods

This is a post-hoc analysis of a single-center prospective study of PICU children followed at the PICU follow-up clinic at CHU Sainte-Justine. Eligible children were admitted to the PICU with ≥2 days of IMV or ≥4 days of NIV. Two months after PICU discharge, patients and families were evaluated by physicians and filled out questionnaires assessing Quality of life (Pediatric Quality of Life Inventory™), development milestones (Ages and Stages Questionnaire), and parental anxiety and depression (Hospital Anxiety and Depression Scale).

Results

One hundred and fifty patients were included from October 2018 to December 2021; 106 patients received IMV (±NIV), and 44 patients received NIV exclusively. Admission diagnoses differed between groups, with 30.2% of patients in the IMV group admitted for a respiratory illness vs. 79.5% in the NIV group. For the entire cohort, QoL scores were 78.1% for the physical domain and 80.1% for the psychological domain, and were similar between groups. Children with a respiratory illness exhibited similar symptoms at follow-up whether they were supported by IMV vs. NIV. For developmental outcomes, only 22.2% of pre-school children had normal scores in all ASQ domains. In the entire cohort, symptoms of anxiety were reported in 29.9% and depression in 24.6 of patients.

Conclusions

PICU survivors undergoing mechanical ventilation, and their families, experienced significant morbidities 2 months after their critical illness, whether they received IMV or NIV. Children with respiratory illness exhibited a higher prevalence of persistent respiratory difficulties post PICU, whether they underwent IMV or NIV. Patients' quality of life and parental symptoms of anxiety and depression did not differ according to the type of respiratory support. These findings justify the inclusion of patients receiving NIV in the PICU in follow-up assessments as well as those receiving IMV.

Pediatric Delirium: An Overlooked Diagnosis?

BACKGROUND

Delirium is well-recognized in adult inpatient care. However, it is often overlooked in children, being mistaken for pain, anxiety, or age-appropriate agitation.

METHODS

To assess the impact of a formal teaching session on the diagnostic rates and management of pediatric delirium (PD) in a tertiary care center, we conducted a retrospective chart review of all hospitalized children diagnosed with PD between August 2003 and August 2018 at the CHU Sainte-Justine (Montreal, Canada). Diagnostic incidence and management were compared before (2003 to 2014) and after (2015 to 2018) a formal teaching session provided to pediatric residents, staff pediatricians, and intensive care physicians in December 2014.

RESULTS

The two cohorts displayed similar demographics, PD symptomatology, PD duration (median: 2 days), and hospital stay duration (median: 11.0 and 10.5 days). However, we saw a major increase in diagnosis frequency after 2014 (from 1.84 to 7.09 cases/year). This increased diagnostic rate was most striking in the pediatric intensive care unit setting. Although symptomatic treatment with antipsychotics and alpha-2 agonists was similar between the two cohorts, patients diagnosed after 2014 were more often weaned from offending medications (benzodiazepines, anesthetics, and anticholinergics). All patients recovered fully.

CONCLUSIONS

Formal teaching on the symptoms and management of PD was associated with an increase in diagnostic rate and an improved management of PD in our institution. Larger studies are required to assess standardized screening tools that may further enhance diagnostic rates and improve care for children with PD.

Prevalence and determinants of anemia at discharge in pediatric intensive care survivors

BACKGROUND

Restrictive transfusion practices are increasingly being followed in pediatric intensive care units (PICU); consequently, more patients are discharged anemic from PICU. Given the possible impact of anemia on long-term neurodevelopmental outcomes, we aim to describe the epidemiology of anemia at PICU discharge in a mixed (pediatric and cardiac) cohort of PICU survivors and to characterize risk factors for anemia.

STUDY DESIGN AND METHODS

We performed a retrospective cohort study in the PICU of a multidisciplinary tertiary-care university-affiliated center. All consecutive PICU survivors for whom a hemoglobin level was available at PICU discharge were included. Baseline characteristics and hemoglobin levels were extracted from an electronic medical records database.

RESULTS

From January 2013 to January 2018, 4750 patients were admitted to the PICU (97.1% survival); discharge hemoglobin levels were available for 4124 patients. Overall, 50.9% (n = 2100) were anemic at PICU discharge. Anemia at PICU discharge was also common in the cardiac surgery population (53.3%), mainly in acyanotic patients; only 24.6% of cyanotic patients were anemic according to standard definitions of anemia. Cardiac surgery patients were transfused more often and at higher hemoglobin levels than medical and non-cardiac surgery patients. Anemia at admission was the strongest predictor of anemia at discharge (odds ratios (OR): 6.51, 95% confidence interval (CI:5.40;7.85)).

DISCUSSION

Half of PICU survivors are anemic at discharge. Further studies are required to determine the course of anemia after discharge and to ascertain whether anemia is associated with adverse long-term outcomes.

Heart Rate Variability in Children with Moderate and Severe Traumatic Brain Injury: A Prospective Observational Study

The aim of this study was to assess the feasibility of continuous monitoring of heart rate variability (HRV) in children with traumatic brain injury (TBI) hospitalized in a pediatric intensive care unit (PICU) and collect preliminary data on the association between HRV, neurological outcome, and complications. This is a prospective observational cohort study in a tertiary academic PICU. Children admitted to the PICU ≤24 hours after moderate or severe TBI were included in the study. Children suspected of being brain dead at PICU entry or with a pacemaker were excluded. Children underwent continuous monitoring of electrocardiographic (ECG) waveforms over 7 days post-TBI. HRV analysis was performed retrospectively, using a standardized, validated HRV analysis software (CIMVA). The occurrence of medical complications (“event”: intracranial hypertension, cerebral hypoperfusion, seizure, and cardiac arrest) was prospectively documented. Outcome of children 6 months post-TBI was assessed using the Glasgow Outcome Scale – Extended Pediatric (GOS-E Peds). Fifteen patients were included over a 20-month period. Thirteen patients had ECG recordings available and 4 had >20% of missing ECG data. When ECG was available, HRV calculation was feasible (average 88%; range 70–97%). Significant decrease in overall HRV coefficient of variation and Poincaré SD2 (p < 0.05) at 6 hours post–PICU admission was associated with an unfavorable outcome (defined as GOS-E Peds ≥ 3, or a deterioration of ≥2 points over baseline score). Several HRV metrics exhibited significant and nonsignificant variation in HRV during event. This study demonstrates that it is feasible to monitor HRV in the PICU provided ECG data are available; however, missing ECG data are not uncommon. These preliminary data suggest that altered HRV is associated with unfavorable neurological outcome and in-hospital medical complications. Larger prospective studies are needed to confirm these findings and to explore if HRV offers reliable and clinically useful prediction data that may help clinical decision making.

Impact of Blood Sampling on Anemia in the PICU: A Prospective Cohort Study

OBJECTIVES

Fifty percent of children are anemic after a critical illness. Iatrogenic blood testing may be a contributor to this problem. The objectives of this study were to describe blood sampling practice in a PICU, determine patient factors associated with increased sampling, and examine the association among blood sampling volume, anemia at PICU discharge, and change in hemoglobin from PICU entry to PICU discharge.

DESIGN

Prospective observational cohort study.

SETTING

PICU of Sainte-Justine University Hospital.

PATIENTS

All children consecutively admitted during a 4-month period.

MEASUREMENTS AND MAIN RESULTS

Four hundred twenty-three children were enrolled. Mean blood volume sampled was 3.9 (±19) mL/kg/stay, of which 26% was discarded volume. Children with central venous or arterial access were sampled more than those without access (p < 0.05). Children with sepsis, shock, or cardiac surgery were most sampled, those with a primary respiratory diagnosis; the least (p < 0.001). We detected a strong association between blood sample volume and mechanical ventilation (H, 81.35; p < 0.0001), but no association with severity of illness (Worst Pediatric Logistic Organ Dysfunction score) (R, -0.044; p = 0.43). Multivariate analysis (n = 314) showed a significant association between the volume of blood sampled (as continuous variable) and anemia at discharge (adjusted OR, 1.63; 95% CI, 1.18-2.45; p = 0.003). We lacked power to detect an association between blood sampling and change in hemoglobin from PICU admission to PICU discharge.

CONCLUSIONS

Diagnostic blood sampling in PICU is associated with anemia at discharge. Twenty-five percent of blood losses from sampling is wasted. Volumes are highest for patients with sepsis, shock, or cardiac surgery, and in patients with vascular access or ventilatory support.

Impact of the Covid-19 Pandemic on Children and Families in PICU Follow-Up Clinic

The novel coronavirus disease 2019 (COVID-19) pandemic disrupted the lives of many families, especially those of children with chronic health problems. Little is known about the impact of this pandemic on the health and well-being of critically ill children and their families after their discharge from pediatric intensive care unit (PICU) hospitalization. This study describes the repercussions of the COVID-19-related lockdown on the physical and psychological wellbeing, quality of life, and access to resources of PICU survivors and their families. This was a prospective cohort study of children and families followed at the Centre Hospitalier Universitaire Ste-Justine PICU follow-up clinic from October 2018 to February 2020. Families were contacted by phone to complete validated questionnaires (Pediatric Quality of Life Inventory, Hospital Anxiety and Depression Scale) and to evaluate the impact of the COVID-19 pandemic on their access to medical care and extrafamilial support. Fifty-five families were contacted between November and December 2020. Quality of life scores were 88.1 ± 16.9 and 83.8 ± 13.9 for physical and psychosocial aspects, respectively. Symptoms of anxiety and depression were detected in 23.6 and 3.6% of respondent parents, respectively. A significant proportion of families reported canceled or delayed health care appointments (65.5%) and difficulty with medication access (12.7%). Twenty-five families (45.5%) reported a significant decrease in income. We could not identify any statistically significant predictors for lower quality of life scores. Difficulty accessing medical care was associated with higher symptoms of anxiety and/or depression in parents on multivariate analysis (p = 0.02). In conclusion, the COVID-19 pandemic has had a significant negative impact on PICU survivors' access to medical resources and extrafamilial support.

The Impact of Implementing a “Pain, Agitation, and Delirium Bundle” in a Pediatric Intensive Care Unit: Improved Delirium Diagnosis

Delirium is associated with significant negative outcomes, yet it remains underdiagnosed in children. We describe the impact of implementing a pain, agitation, and delirium (PAD) bundle on the rate of delirium detection in a pediatric intensive care unit (PICU). This represents a single-center, pre-/post-intervention retrospective and prospective cohort study. The study was conducted at a PICU in a quaternary university-affiliated pediatric hospital. All patients consecutively admitted to the PICU in October and November 2017 and 2018. Purpose of the study was describe the impact of the implementation of a PAD bundle. The rate of delirium detection and the utilization of sedative and analgesics in the pre- and post-implementation phases were measured. A total of 176 and 138 patients were admitted during the pre- and post-implementation phases, respectively. Of them, 7 (4%) and 44 (31.9%) were diagnosed with delirium (p < 0.001). Delirium was diagnosed in the first 48 hours of PICU admission and lasted for a median of 2 days (interquartile range [IQR]: 2–4). Delirium diagnosis was higher in patients receiving invasive ventilation (p < 0.001). Compliance with the PAD bundle scoring was 79% for the delirium scale. Score results were discussed during medical rounds for 68% of the patients in the post-implementation period. The number of patients who received opioids and benzodiazepines and the cumulative doses were not statistically different between the two cohorts. More patients received dexmedetomidine and the cumulative daily dose was higher in the post-implementation period (p < 0.001). The implementation of a PAD bundle in a PICU was associated with an increased recognition of delirium diagnosis. Further studies are needed to evaluate the impact of this increased diagnostic rate on short- and long-term outcomes.

Prevalence of Acute Rehabilitation for Kids in the PICU: A Canadian Multicenter Point Prevalence Study

OBJECTIVES

To evaluate mobilization practices, barriers, and mobility-related adverse events in Canadian PICUs.

DESIGN

National 2-day point prevalence study.

SETTING

Thirteen PICUs across Canada.

PATIENTS

Children with a minimum 72-hour PICU length of stay on the allocated study day.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Outcomes of interest were the prevalence and nature of mobilization activities, rehabilitation resources, adverse events, and factors associated with out-of-bed mobility and therapist-provided mobility. Two PICUs (15%) had early mobilization practice guidelines, and one PICU (8%) reported a formal process for engaging families in the mobilization of patients. The prevalence of mobilization was 110 of 137 patient-days (80%). The commonest activity was out-of-bed mobility (87/137; 64% patient-days); there was no active mobilization on 46 patient-days (34%). Therapists provided mobility on 33% of patient-days. Mobility was most commonly facilitated by nurses (74% events) and family (49% events). Family participation was strongly associated with out-of-bed mobility (odds ratio 6.4; p = 0.001). Intubated, mechanically ventilated patients were mobilized out-of-bed on 18 of 50 patient-days (36%). However, the presence of an endotracheal tube, vasoactive infusions, and age greater than or equal to 3 years were independently associated with not being mobilized out-of-bed. Barriers were reported on 58 of 137 patient-days (42%), and adverse events occurred in 22 of 387 mobility events (6%).

CONCLUSIONS

Mobilization is common and safe, and the majority of children in Canadian PICUs are being mobilized out-of-bed, even when mechanically ventilated. Family engagement in PICU-based rehabilitation is increasing. This study provides encouraging evidence that common barriers can be overcome in order to safely mobilize children in PICUs.

Variation in Treatment and Outcomes of Children With Acute Disseminated Encephalomyelitis

OBJECTIVES

To characterize variation in treatments and outcomes of pediatric patients admitted to children's hospitals with acute disseminated encephalomyelitis (ADEM).

METHODS

In this retrospective cohort study, we used data from the Pediatric Health Information System. Children >30 days old who were hospitalized from 2010 to 2015 with ADEM were included. Variables analyzed were treatments and admission to an ICU. Primary outcomes were discharge disposition and readmissions for relapses (ADEM readmissions) or for continued comorbidities (non-ADEM readmissions).

RESULTS

A total of 954 patients with ADEM had 1117 admissions. Treatments included steroids (80%), immunoglobulin (22%), and plasmapheresis (6.6%); 15% of admissions included none of these treatments. Treatments varied by center (P < .001). Thirty-four percent of admissions included ICU admission, which was associated with an increased number and duration of treatments (P < .01). The discharge disposition was home in 85% of admissions; home with health services, rehab facility, or other in 13.6%; and mortality in 1.4%. Twelve percent (117 of 954) of patients had >1 admission for ADEM. Treatment choice and ICU stay were not associated with ADEM readmissions. Sixteen percent (181 of 1101) of ADEM admissions had a non-ADEM readmission within 90 days. Prolonged ICU hospitalization was associated with non-ADEM readmission (adjusted odds ratio 1.9; P = .017) and decreased likelihood of discharge from the hospital to home (adjusted odds ratio 0.1; P < .001). After adjusting for ICU duration, treatment choice and duration were not associated with non-ADEM readmission or hospital disposition.

CONCLUSIONS

Significant variation in ADEM treatment exists across centers. Admission to an ICU for ADEM was associated with increased immunotherapy, additional health services at discharge, and readmission for diagnoses other than ADEM.

Traduction et validation de l’échelle d’évaluation du delirium pédiatrique de Cornell en version française

Objectif : Le delirium est commun chez les patients de soins intensifs pédiatriques (SIP), mais sous-reconnu par les cliniciens en l’absence d’une échelle de dépistage de delirium pédiatrique. L’objectif de cette étude était donc de traduire et de valider l’échelle d’évaluation du delirium pédiatrique de Cornell en version française.

Patients et méthodes : Pour la traduction, la méthode reconnue de rétrotraduction a été utilisée. L’échelle Cornell Assessment of Pediatric Delirium a été traduite de l’anglais vers le français par une traductrice et un médecin francophones. Les deux versions ont été mises en commun et harmonisées, puis cette version a été rétrotraduite en anglais par un médecin anglophone. Cette traduction a ensuite été comparée à la version source par les auteurs originaux qui ont pprouvé la traduction. La version française finale de l’échelle a été validée sur 25 patients admis dans notre unité médicochirurgicale de SIP de 32 lits. Chaque patient a été évalué de manière indépendante par deux infirmières. La reproductibilité interobservateur a été mesurée par un coefficient de Kappa.

Résultats : Cinquante mesures ont été obtenues au cours des 25 évaluations. La concordance interobservateur était presque parfaite, avec un coefficient de Kappa de 0,92. Le temps médian nécessaire pour compléter l’échelle était de 51 secondes.

Conclusion : La version française de l’échelle d’évaluation du delirium pédiatrique de Cornell est valide et reproductible dans un milieu de SIP.

Acute pediatric hyperammonemia: current diagnosis and management strategies

Acute hyperammonemia may induce a neurologic impairment leading to an acute life-threatening condition. Coma duration, ammonia peak level, and hyperammonemia duration are the main risk factors of hyperammonemia-related neurologic deficits and death. In children, hyperammonemia is mainly caused by severe liver failure and inborn errors of metabolism. In an acute setting, obtaining reliable plasma ammonia levels can be challenging because of the preanalytical difficulties that need to be addressed carefully. The management of hyperammonemia includes 1) identification of precipitating factors and cerebral edema presence, 2) a decrease in ammonia production by reducing protein intake and reversing catabolism, and 3) ammonia removal with pharmacologic treatment and, in the most severe cases, with extracorporeal therapies. In case of severe coma, transcranial Doppler ultrasound could be the method of choice to noninvasively monitor cerebral blood flow and titrate therapies.

Patient-ventilator asynchrony during conventional mechanical ventilation in children

Background

We aimed (1) to describe the characteristics of patient–ventilator asynchrony in a population of critically ill children, (2) to describe the risk factors associated with patient–ventilator asynchrony, and (3) to evaluate the association between patient–ventilator asynchrony and ventilator-free days at day 28.

Methods

In this single-center prospective study, consecutive children admitted to the PICU and mechanically ventilated for at least 24 h were included. Patient–ventilator asynchrony was analyzed by comparing the ventilator pressure curve and the electrical activity of the diaphragm (Edi) signal with (1) a manual analysis and (2) using a standardized fully automated method.

Results

Fifty-two patients (median age 6 months) were included in the analysis. Eighteen patients had a very low ventilatory drive (i.e., peak Edi < 2 µV on average), which prevented the calculation of patient–ventilator asynchrony. Children spent 27% (interquartile 22–39%) of the time in conflict with the ventilator. Cycling-off errors and trigger delays contributed to most of this asynchronous time. The automatic algorithm provided a NeuroSync index of 45%, confirming the high prevalence of asynchrony. No association between the severity of asynchrony and ventilator-free days at day 28 or any other clinical secondary outcomes was observed, but the proportion of children with good synchrony was very low.

Conclusion

Patient–ventilator interaction is poor in children supported by conventional ventilation, with a high frequency of depressed ventilatory drive and a large proportion of time spent in asynchrony. The clinical benefit of strategies to improve patient–ventilator interactions should be evaluated in pediatric critical care.

Recent Advances in Pediatric Ventilatory Assistance

In this review on respiratory assistance, we aim to discuss the following recent advances: the optimization and customization of mechanical ventilation, the use of high-frequency oscillatory ventilation, and the role of noninvasive ventilation. The prevention of ventilator-induced lung injury and diaphragmatic dysfunction is now a key aspect in the management of mechanical ventilation, since these complications may lead to higher mortality and prolonged length of stay in intensive care units. Different physiological measurements, such as esophageal pressure, electrical activity of the diaphragm, and volumetric capnography, may be useful objective tools to help guide ventilator assistance. Companies that design medical devices including ventilators and respiratory monitoring platforms play a key role in knowledge application. The creation of a ventilation consortium that includes companies, clinicians, researchers, and stakeholders could be a solution to promote much-needed device development and knowledge implementation.

Use of Transcranial Doppler for Management of Central Nervous System Infections in Critically Ill Children

BACKGROUND

The primary objective of this study was to characterize changes in cerebral blood flow measured using transcranial Doppler in children with central nervous system infections. We hypothesized that children with central nervous system infections have abnormal cerebral blood flow, associated with a greater frequency of complications and poor neurological outcome.

METHODS

We conducted a single-center, retrospective study of children admitted to the neonatal or pediatric intensive care unit with central nervous system infection and undergoing transcranial Doppler as part of routine care between March 2011 and July 2015.

RESULTS

A total of 20 children with central nervous system infection underwent 35 transcranial Dopplers. The mean age was 8.2 ± 6.3 years, including 12 boys and eight girls. The most common infection was meningitis (n = 11, 55%), with the remainder comprising encephalitis (15%), meningoencephalitis (20%), and abscess or empyema (10%). Bacterial (n = 10, 50%) and viral (n = 6) sources were common with only one (5%) fungal infection and three (15%) unknown but presumed viral etiology. The patients underwent transcranial Doppler 4 ± 9 days after intensive care unit admission. Mean cerebral blood flow velocities were overall increased compared with reference values for age (healthy children and critically ill children) mostly because of hyperemia (n = 21, 60%) and vasospasm (6%). Hypoperfusion (cerebral blood flow velocity <1 S.D. of normal value) in at least one vessel was associated with morbidity (intubation, vasoactive medications, neurosurgery, cardiac arrest) (P = 0.04) and mortality (P = 0.03). Two patients had increased intracranial pressure and hyperventilation was safely achieved with transcranial Doppler monitoring to avoid ischemia. Serial transcranial Dopplers were used to guide blood pressure management.

CONCLUSIONS

Transcranial Doppler can be used in children with central nervous system infection as a tool to assess cerebral blood flow. In this retrospective study, cerebral hypoperfusion was associated with increased morbidity and mortality. If transcranial Doppler is to guide medical therapy and management of cerebral blood flow in children with central nervous system infections, these results will need to be validated in prospective studies with a more homogenous population of children with encephalitis or meningitis.

Posterior Circulation Ischemia or Occlusion in Five Adults With Failing Fontan Circulation

BACKGROUND

Palliative procedures performed before the Fontan procedure may require ligation of the subclavian arteries, thereby affecting flow to the vertebral arteries. In adults with functionally univentricular heart disease, the implications of altered brainstem vascular anatomy for perioperative management of failing Fontan circulation are not known.

METHODS

We identified abnormal posterior circulation anatomy in an adult patient with failing Fontan circulation who experienced a brainstem stroke after Fontan conversion. We then changed our clinical practice to include detailed preoperative neurologic evaluation of adults with univentricular heart disease and failing Fontan circulation. Here, we report the clinical and neuroimaging findings in 5 consecutive patients before and after this change in practice.

RESULTS

Five patients ages 28 to 42 years had Fontan procedures performed in childhood, and underwent either Fontan conversion or cardiac transplantation. Patient 1 experienced an episode of decreased cerebral perfusion pressure on postoperative day 3, and experienced an ischemic brainstem stroke causing transient locked-in syndrome. A change in practice was made, and patients 2, 3, and 4 were evaluated preoperatively by the neurocritical care service. These patients then had higher target blood pressures perioperatively and no neurologic injury. Patient 5 was evaluated for symptoms consistent with subclavian steal. Neuroimaging in 3 patients was abnormal, with atrophic vertebral arteries, an occluded vertebral artery, and retrograde perfusion of a vertebral artery.

CONCLUSIONS

In adults with failing Fontan circulation there is a potential for neurologic complications as a result of venous congestion with elevated central venous pressures, and aberrant posterior circulation. The patient's history and brain imaging may be used to identify at-risk patients and to tailor perioperative management during Fontan conversion or heart transplantation to mitigate the risk for brainstem ischemia.

Cerebrovascular Pressure Reactivity in Children with TBI

Investigators from University of Melbourne, Australia, studied Pressure-Reactivity Index (PRx) and optimal Cerebral Perfusion Pressure (CPP) in 36 children aged between 6 months and 16 years treated for traumatic brain injury (TBI) at the Royal Children's Hospital, Melbourne, from 2007 to 2013.

Childhood Stroke and Congenital Heart Disease

Investigators from the University of California performed a case-control study of the association of stroke with congenital heart disease (CHD) within a population of 2.5 million children in Northern California.

Tonic diaphragmatic activity in critically ill children with and without ventilatory support

BACKGROUND

Infants have to actively maintain their end expiratory lung volume (EELV). In mechanically ventilated infants, the diaphragm stays activated until the end of expiration (tonic activity), contributing to EELV maintenance. It is unclear whether tonic activity compensates for the lack of laryngeal braking due to intubation or if it is normally present.

OBJECTIVE

To determine if tonic diaphragm activity remains after extubation in infants, and if it can be observed in older children.

METHODS

Prospective observational study of pediatric patients ventilated for >24 hr. Diaphragm electrical activity (EAdi) was recorded using a specific nasogastric catheter during four periods: (i) the acute phase, (ii) pre-extubation, (iii) post-extubation, and (iv) at PICU discharge. Tonic EAdi was defined as the EAdi in the last quartile of expiration.

RESULTS

Fifty-five patients, median age 10 months (Interquartile range: 1-48) were studied. In infants (<1 year, n = 28), tonic EAdi was always present, and represented 33% (22-43) of inspiratory EAdi at PICU discharge. No significant change was observed between pre- and post-extubation periods. In older patients (n = 27), tonic activity was negligible as a whole, but 10 patients exhibited significant tonic EAdi at one time-point during PICU stay. Bronchiolitis was the only independent factor associated with tonic EAdi.

CONCLUSIONS

In infants, tonic EAdi remains involved in ventilatory control after extubation and restoration of laryngeal braking. Tonic EAdi may play a pathophysiological role in bronchiolitis and it can be reactivated in older patients. The interest of tonic EAdi as a tool to titrate mechanical ventilation warrants further evaluation.

Evolution of inspiratory diaphragm activity in children over the course of the PICU stay

PURPOSE

Diaphragm function should be monitored in critically ill patients, as full ventilatory support rapidly induces diaphragm atrophy. Monitoring the electrical activity of the diaphragm (EAdi) may help assess the level of diaphragm activity, but such monitoring results are difficult to interpret because reference values are lacking. The aim of this study was to describe EAdi values in critically ill children during a stay in the pediatric intensive care unit (PICU), from the acute to recovery phases, and to assess the impact of ventilatory support on EAdi.

METHODS

This was a prospective longitudinal observational study of children requiring mechanical ventilation for ≥24 h. EAdi was recorded using a validated method in the acute phase, before extubation, after extubation, and before PICU discharge.

RESULTS

Fifty-five critically ill children were enrolled in the study. Median maximum inspiratory EAdi (EAdimax) during mechanical ventilation was 3.6 [interquartile range (IQR) 1.2-7.6] μV in the acute phase and 4.8 (IQR 2.0-10.7) μV in the pre-extubation phase. Periods of diaphragm inactivity (with no detectable inspiratory EAdi) were frequent during conventional ventilation, even with a low level of support. EAdimax in spontaneous ventilation was 15.4 (IQR 7.4-20.7) μV shortly after extubation and 12.6 (IQR 8.1-21.3) μV before PICU discharge. The difference in EAdimax between mechanical ventilation and post-extubation periods was significant (p < 0.001). Patients intubated mainly because of a lung pathology exhibited higher EAdi (p < 0.01), with a similar temporal increase.

CONCLUSIONS

This is the first systematic description of EAdi evolution in children during their stay in the PICU. In our patient cohort, diaphragm activity was frequently low in conventional ventilation, suggesting that overassistance or oversedation is common in clinical practice. EAdi monitoring appears to be a helpful tool to detect such situations.