Mechanical power and normalized mechanical power in pediatric acute respiratory distress syndrome.

Background: Mechanical power (MP) refers to the energy transmitted over time to the respiratory system and serves as a unifying determinant of ventilator-induced lung injury. MP normalization is required to account for developmental changes in children. We sought to examine the relationship between mechanical energy (MEBW), MP normalized to body weight (MPBW), and MP normalized to respiratory compliance (MPCRS) concerning the severity and outcomes of pediatric acute respiratory distress syndrome (pARDS). Method: In this retrospective study, children aged 1 month to 18 years diagnosed with pARDS who underwent pressure-control ventilation for at least 24 h between January 2017 and September 2020 were enrolled. We calculated MP using Becher's equation. Multivariable logistic regression analysis adjusted for age, pediatric organ dysfunction score, and oxygenation index (OI) was performed to determine the independent association of MP and its derivatives 24 h after diagnosing pARDS with 28-day mortality. The association was also studied for 28 ventilator-free days (VFD-28) and the severity of pARDS in terms of OI. Results: Out of 246 admitted with pARDS, 185 were eligible, with an overall mortality of 43.7%. Non-survivors exhibited higher severity of illness, as evidenced by higher values of MP, MPBW, and MEBW. Multivariable logistic regression analysis showed that only MEBW but not MP, MPBW, or MPCRS at 24 h was independently associated with mortality [adjusted OR: 1.072 (1.002-1.147), p = 0.044]. However, after adjusting for the type of pARDS, MEBW was not independently associated with mortality [adjusted OR: 1.061 (0.992-1.136), p = 0.085]. After adjusting for malnutrition, only MP at 24 h was found to be independently associated. Only MPCRS at 1-4 and 24 h but not MP, MPBW, or MEBW at 24 h of diagnosing pARDS was significantly correlated with VFD-28. Conclusions: Normalization of MP is better related to outcomes and severity of pARDS than non-normalized MP. Malnutrition can be a significant confounding factor in resource-limited settings.

Dynamic Airway Driving Pressure and Outcomes in Children With Acute Hypoxemic Respiratory Failure.

BACKGROUND: Limited adult data suggest that airway driving pressure might better reflect the potential risk for lung injury than tidal volume based on ideal body weight, and the parameter correlates with mortality in ARDS. There is a lack of data about the effect of driving pressure on mortality in pediatric ARDS. This study aimed to evaluate the effect of driving pressure on morbidity and mortality of children with acute hypoxemic respiratory failure. METHODS: This retrospective cohort study was performed in a tertiary level pediatric ICU. Children who received invasive mechanical ventilation for acute hypoxemic respiratory failure (defined as [Formula: see text] < 300 within 24 h after intubation), in a 2-y period were included. The cohort was divided into 2 groups based on the highest dynamic driving pressure (ΔP, calculated as the difference between peak inspiratory pressure and PEEP) in the first 24 h, with a cutoff value of 15 cm H2O. RESULTS: Of the 380 children who were mechanically ventilated during the study period, 101 children who met eligibility criteria were enrolled. Common diagnoses were pneumonia (n = 51), severe sepsis (n = 24), severe dengue (n = 10), and aspiration pneumonia (n = 7). In comparison to the group with high ΔP (ie, ≥ 15 cm H2O), children in the group with low ΔP (ie, < 15 cm H2O) had significantly lower median (interquartile range) duration of ventilation (5 [4-6] d vs 8 [6-11] d, P < .001], ICU length of stay (6 [5-8] d vs 12 [8-15] d, P < .001], and more ventilator-free days at day 28 (23 [20-24] vs 17 [0-22] d, P < .001). Logistic regression analysis also suggested driving pressure as an independent predictor of morbidity after adjusting for confounding variables. However, there was no statistically significant difference in mortality between the 2 groups (17% in low ΔP vs 24% in high ΔP, P = .38). Subgroup analysis of 65 subjects who fulfilled ARDS criteria yielded similar results with respect to mortality and morbidity. CONCLUSIONS: Below a threshold of 15 cm H2O, ΔP was associated with significantly decreased morbidity in children with acute hypoxemic respiratory failure.

Inhaled Pulmonary Vasodilators: Are There Indications Within the Pediatric ICU?

Inhaled nitric oxide (INO) is only FDA-cleared for neonates (> 34 weeks gestation) with hypoxic respiratory failure-associated pulmonary hypertension. Off-label use of INO is common in the pediatric population despite a lack of evidence regarding survival benefit, questioning whether the therapy should be considered outside the neonatal period. A lack of definitive evidence combined with increasing health-care costs has led to the use of less costly inhaled prostacyclin as an alternative to INO, presenting unique patient safety concerns. We evaluate the current evidence and patient safety considerations regarding inhaled pulmonary vasodilators in the pediatric population.

The history and physics of heliox.

Since the discovery of helium in 1868, it has found numerous applications in industry and medicine. Its low density makes helium potentially valuable in respiratory care applications, to reduce work of breathing, improve distribution of ventilation, reduce minute volume requirement, and improve aerosol delivery. This review includes a brief history of the use of heliox (a mixture of helium and oxygen) and addresses issues related to the physics of gas flow when heliox is used. Specifically covered are the Hagen-Poiseuille equation, laminar versus turbulent flow, the Reynolds number, orifice flow, Bernoulli's principle, Graham's law, wave speed, and thermal conductivity.

Heliox during mechanical ventilation.

The indications for heliox during mechanical ventilation are lower-airway obstruction, especially with hypercarbia; need to enhance aerosol delivery to lung periphery; and need to facilitate weaning from mechanical ventilation. Certain ventilators perform relatively well with heliox and are not substantially affected by it. It is preferable to connect the heliox to the air inlet of the ventilator, because this results in more consistent delivery of oxygen and tidal volume. When administering heliox, pay close attention and directly monitor the actual tidal volume and fraction of inspired oxygen.

Utility of a novel quantitative handheld microstream capnometer during transport of critically ill children.

OBJECTIVE: Critically ill children often require endotracheal intubation before and during interhospital transport. Accurate placement and maintenance of the endotracheal tube (ETT) is crucial. The new Pediatric Advanced Life Support guidelines require confirmation of proper ETT position immediately after intubation and during transport by capnography or end-tidal carbon dioxide (ETco(2)) detection in all children with a perfusing rhythm. Currently, there are no practical alternatives for monitoring ETco(2) during pediatric transport. Therefore, we evaluated NPB-75, a quantitative handheld microstream capnometer, during transport of children to our urban children's hospital. METHODS: Consecutive intubated patients who were transported by ground ambulance or rotorcraft were prospectively enrolled into the study. Physical examination, colorimetric CO(2) detector, pulse oximetry, and, in most cases, chest radiograph confirmed the initial ETT position. The capnometer was then attached, and ETco(2) readings were obtained before and during transport by nurses or respiratory therapists who also completed a brief questionnaire regarding the monitor immediately after every transport. A numerical light-emitting diode display and graphic liquid crystal display waveform confirmed the presence of ETco(2). An audiovisual alarm alerted the transport personnel when CO(2) was not detected. RESULTS: Fifty patients comprised the study group, ages birth to 15.3 years (median, 4 months) and weighing 1.63 to 70 kg (median, 5.25 kg). Nineteen patients were transported by ground ambulance and 31 by rotorcraft. The capnometer confirmed ETT position during transport in all patients. The audiovisual alarm of the capnometer immediately detected a ventilator disconnection from the ETT during one air transport. The size of the device was evaluated as "just right" in 37 of 50 transports, "easy to secure" in 46 of 50, and "useful" in all 50 transports. There were no false-negative readings, occlusion, or kinking of tubing during transport. NPB-75 was specifically useful for setting optimal ventilatory support in 2 patients with raised intracranial pressure who required controlled ventilation. Furthermore, it confirmed adequate ventilation when the ventilator falsely detected a low respiratory rate in a newborn with a congenital heart disease for whom pulse oximetry was unreliable. The ETco(2) waveform detected air trapping in 2 ventilated asthmatic patients. CONCLUSIONS: This lightweight microstream capnometer with a 4-hour battery life and audiovisual alarms functioned well in the prehospital setting. It provided both quantitative and graphic real-time detection of ETco(2) in intubated patients, which was of critical importance for the optimal management of patients during transport.

Unexpected increased mortality after implementation of a commercially sold computerized physician order entry system.

OBJECTIVE: In response to the landmark 1999 report by the Institute of Medicine and safety initiatives promoted by the Leapfrog Group, our institution implemented a commercially sold computerized physician order entry (CPOE) system in an effort to reduce medical errors and mortality. We sought to test the hypothesis that CPOE implementation results in reduced mortality among children who are transported for specialized care. METHODS: Demographic, clinical, and mortality data were collected of all children who were admitted via interfacility transport to our regional, academic, tertiary-care level children's hospital during an 18-month period. A commercially sold CPOE program that operated within the framework of a general, medical-surgical clinical application platform was rapidly implemented hospital-wide over 6 days during this period. Retrospective analyses of pre-CPOE and post-CPOE implementation time periods (13 months before and 5 months after CPOE implementation) were subsequently performed. RESULTS: Among 1942 children who were referred and admitted for specialized care during the study period, 75 died, accounting for an overall mortality rate of 3.86%. Univariate analysis revealed that mortality rate significantly increased from 2.80% (39 of 1394) before CPOE implementation to 6.57% (36 of 548) after CPOE implementation. Multivariate analysis revealed that CPOE remained independently associated with increased odds of mortality (odds ratio: 3.28; 95% confidence interval: 1.94-5.55) after adjustment for other mortality covariables. CONCLUSIONS: We have observed an unexpected increase in mortality coincident with CPOE implementation. Although CPOE technology holds great promise as a tool to reduce human error during health care delivery, our unanticipated finding suggests that when implementing CPOE systems, institutions should continue to evaluate mortality effects, in addition to medication error rates, for children who are dependent on time-sensitive therapies.

Cumulative fluid intake minus output is not associated with ventilator weaning duration or extubation outcomes in children.

OBJECTIVE: The effect of fluid balance on respiratory outcomes for critically ill children has not been evaluated. The only indicator of fluid balance routinely recorded across our intensive care units was estimated fluid intake and output. We sought to determine whether cumulative intake minus output (I-O) at the start of weaning predicted weaning duration and whether cumulative I-O at extubation predicted extubation failure. DESIGN: Prospective observational study. SETTING: Ten pediatric intensive care units. PATIENTS: Cumulative I-O was recorded daily for 301 mechanically ventilated children (<18 yrs of age) from November 1999 through April 2001. INTERVENTIONS: Cumulative I-O was recorded during a study of weaning strategies and extubation failure in which mechanical ventilation of the majority of patients during weaning and extubation was managed according to a protocol that did not include fluid balance indicators. Outcomes were the time to successful removal of ventilatory support and the rate of initial extubation failure. MEASUREMENTS AND MAIN RESULTS: Relationships between cumulative I-O and outcomes were assessed by means of proportional hazards and logistic regression. The mean cumulative I-O per kilogram of ideal body weight at the start of weaning was 101 mL (sd, 180). Cumulative I-O at the time weaning was initiated did not predict duration of mechanical ventilator weaning. The mean cumulative I-O per kilogram of ideal body weight at extubation was 136 mL (sd, 237). Cumulative I-O at extubation did not predict extubation outcome. There was an association between cumulative I-O at extubation and the duration of weaning in cases not managed by a protocol. CONCLUSION: Although routinely recorded, cumulative fluid I-O does not appear to have clinical utility in cases managed according to a mechanical ventilator protocol in which tidal volume and oxygenation on minimal levels of ventilator support are systematically tested.

The feasibility of conducting clinical trials in infants and children with acute respiratory failure.

Designing robust clinical trials in critically ill, mechanically ventilated children requires an understanding of the epidemiology and course of pediatric respiratory failure. As part of a clinical trial, we screened all mechanically ventilated children in nine large pediatric intensive care units (ICUs) across North America for 6 consecutive months. Of 6,403 total ICU admissions, 1,096 (17.1%) required mechanical ventilator support for a minimum of 24 hours. Of these, 701 (64%) met one or more exclusion criteria for trial enrollment. Common reasons for exclusion were upper airway obstruction (13.5%) and cyanotic congenital heart disease (11.5%). Life support interventions were restricted for 9.7% of patients, and 5.5% were chronically ventilator dependent. In the patients who were eligible for respiratory failure studies, 62.4% had an acute primary diagnosis of pulmonary disease, 14.2% neurologic disease, and 8.9% cardiac disease. Chronic underlying conditions were present in 43.2% of the patients. The most common acute diagnosis was bronchiolitis in infants (43.6%) and pneumonia in children 1 year old and older (24.5%). Mortality was rare (1.6%), and the median duration of ventilation was 7 days. The design of clinical trials in critically ill children is feasible but must account for the diverse population, infrequent mortality, and short duration of mechanical ventilation.

Role of laboratory in the management of phenylbutazone poisoning.

We report a rare case of intentional overdose of phenylbutazone in a 15-yr-old female. The patient exhibited symptoms of phenylbutazone toxicity and the presence of the drug was confirmed by gas chromatography mass-spectrometry (GC-MS) analysis of the initial urine sample. The patient underwent plasmapheresis to remove the drug from the circulation. Semiquantitation of sequential serum samples by GC-MS revealed elimination of phenylbutazone by day 5 of admission at which time the plasmapheresis was discontinued. Elevated blood urea nitrogen (BUN) and creatinine returned to normal. Analysis of biomarkers for liver necrosis and regeneration in sequential serum samples revealed the restoration of normal liver function by day 5. This case further confirms our previous observations that biomarkers for liver necrosis and regeneration can predict the outcome of patients with liver damage due to toxins.

Effect of mechanical ventilator weaning protocols on respiratory outcomes in infants and children: a randomized controlled trial.

CONTEXT: Ventilator management protocols shorten the time required to wean adult patients from mechanical ventilation. The efficacy of such weaning protocols among children has not been studied. OBJECTIVE: To evaluate whether weaning protocols are superior to standard care (no defined protocol) for infants and children with acute illnesses requiring mechanical ventilator support and whether a volume support weaning protocol using continuous automated adjustment of pressure support by the ventilator (ie, VSV) is superior to manual adjustment of pressure support by clinicians (ie, PSV). DESIGN AND SETTING: Randomized controlled trial conducted in the pediatric intensive care units of 10 children's hospitals across North America from November 1999 through April 2001. PATIENTS: One hundred eighty-two spontaneously breathing children (<18 years old) who had been receiving ventilator support for more than 24 hours and who failed a test for extubation readiness on minimal pressure support. INTERVENTIONS: Patients were randomized to a PSV protocol (n = 62), VSV protocol (n = 60), or no protocol (n = 60). MAIN OUTCOME MEASURES: Duration of weaning time (from randomization to successful extubation); extubation failure (any invasive or noninvasive ventilator support within 48 hours of extubation). RESULTS: Extubation failure rates were not significantly different for PSV (15%), VSV (24%), and no protocol (17%) (P =.44). Among weaning successes, median duration of weaning was not significantly different for PSV (1.6 days), VSV (1.8 days), and no protocol (2.0 days) (P =.75). Male children more frequently failed extubation (odds ratio, 7.86; 95% confidence interval, 2.36-26.2; P<.001). Increased sedative use in the first 24 hours of weaning predicted extubation failure (P =.04) and, among extubation successes, duration of weaning (P<.001). CONCLUSIONS: In contrast with adult patients, the majority of children are weaned from mechanical ventilator support in 2 days or less. Weaning protocols did not significantly shorten this brief duration of weaning.