Heidi J. Dalton

Prospective Evaluation of Propofol Anesthesia in the Pediatric Intensive Care Unit for Elective Oncology Procedures in Ambulatory and Hospitalized Children

Objectives. To evaluate our experience with propofol anesthesia delivered by pediatric intensivists in the pediatric intensive care unit (PICU) to facilitate elective oncology procedures in children performed by pediatric oncologists. Methods. Elective oncology procedures performed with propofol anesthesia in our multidisciplinary, university-affiliated PICU were prospectively evaluated over a 7-month period. Ambulatory and hospitalized children were prescheduled for their procedure, underwent a medical evaluation, and met fasting requirements before the start of anesthesia. Continuous cardiorespiratory and neurologic monitoring was performed by a pediatric intensivist and a PICU nurse, while the procedure was performed by a pediatric oncologist. Propofol was delivered in intermittent boluses to achieve the desired level of anesthesia. Information studied included patient demographics, procedures performed, induction and total doses of propofol used, the duration of the different phases of the patients PICU stay, the occurrence of side effects, the need for therapeutic interventions, and the incidence of recall of the procedure. Results. Fifty procedures in 28 children (mean age: 7.5 ± 4.3 years) were evaluated. Sixty-one percent of patients had established diagnoses. Fifty-four percent of procedures were lumbar puncture with intrathecal chemotherapy administration and 26% of procedures were bone marrow aspirations with biopsy. Induction propofol doses were 2.0 ± .8 mg/kg for ambulatory and hospitalized patients, while total propofol doses were 6.6 ± 2.3 mg/kg and 7.9 ± 2.4 mg/kg for ambulatory and hospitalized patients, respectively. Induction time was 1.5 ± .7 minutes, recovery time was 23.4 ± 11.5 minutes, and total PICU time was 88.8 ± 27.7 minutes. Transient decreases in systolic blood pressure less than the fifth percentile for age occurred in 64% of procedures, with a mean decrease of 25% ± 10%. Intravenous fluids were administered in 31% of these cases. Hypotension was more common in ambulatory patients but was not predicted by propofol dose, anesthesia time, or age. Partial airway obstruction was noted in 12% of procedures while apnea requiring bag-valve-mask ventilation occurred in 2% of procedures. Neither was associated with age, propofol dose, or the duration of anesthesia. All procedures were successfully completed and there were no incidences of recall of the procedure. Conclusions. Propofol anesthesia is effective in achieving patient comfort and amnesia, while optimizing conditions for elective oncology procedures in children. Although transient hypotension and respiratory depression may occur, propofol anesthesia seems to be safe to use for these procedures in the PICU setting. Recovery from anesthesia was rapid and total stay was brief. Under the proper conditions, propofol anesthesia delivered by pediatric intensivists in the PICU is a reasonable option available to facilitate invasive oncology procedures in children.

Calf's lung surfactant extract in acute hypoxemic respiratory failure in children

OBJECTIVE Open-label trial of the safety and short-term efficacy of calfs lung surfactant in pediatric respiratory failure. DESIGN Multi-institutional, uncontrolled, observational trial. SETTING Six pediatric intensive care units of tertiary medical centers. PATIENTS Twenty-nine children with acute hypoxemic respiratory failure, characterized by diffuse, bilateral, pulmonary infiltrates, need for ventilator support, and an oxygenation index of > or = 7. INTERVENTIONS Up to four doses of intratracheal surfactant (80 mL/m2). MEASUREMENTS AND MAIN RESULTS Ventilator parameters, arterial blood gases, and derived oxygenation and ventilation indices were recorded before, and at intervals after, surfactant administration. Complications and outcome measures were also noted. There was immediate improvement in oxygenation and moderation of ventilator support associated with surfactant administration in 24 of 29 patients. A modest but statistically insignificant effect was seen with subsequent doses. The only complications occurred in three patients who developed airleaks, two of which were coincident with surfactant administration. The overall mortality rate was 14%, which compares favorably with other published series. CONCLUSIONS Administration of calfs lung surfactant appears to be safe and is associated with rapid improvement in oxygenation and moderation of ventilator support in children with acute hypoxemic respiratory failure. These results set the stage for a randomized, controlled study.

Interleukin-6, interleukin-8, and a rapid and sensitive assay for calcitonin precursors for the determination of bacterial sepsis in febrile neutropenic children.

Objective: Children with cancer often develop febrile illnesses after cytotoxic chemotherapy. Determining which children have serious bacterial infections in this vulnerable period would be valuable. We evaluated the ability of a rapid and sensitive assay for the concentration of calcitonin precursors (CTpr) as a sensitive diagnostic marker for bacterial sepsis in febrile, neutropenic children and determined the utility of measuring cytokines to improve the predictive value of this approach. Design: Prospective cohort study. Setting: Academic children’s hospital. Patients: Fifty-six children (aged 5 months to 17 yrs) with a known malignancy who presented with fever and neutropenia. Interventions: Serial blood samples were obtained (admission, 24 hrs, and 48 hrs), and concentrations of CTpr, interleukin-6, and interleukin-8 were determined. Demographic and laboratory data from the patients were collected from the medical record. Measurements and Main Results: Sixteen (29%) of the children met the criteria for bacterial sepsis. Plasma levels of CTpr and interleukin-8, but not interleukin-6, were increased at all time points in children with sepsis compared with those without sepsis. CTpr at 24 and 48 hrs after admission were reliable markers for sepsis (area under the curve = 0.92 and 0.908, respectively). Logistic regression using CTpr at 24 hrs in addition to interleukin-8 at 48 hrs produced the best-fit models associated with sepsis. Using cutoff values of CTpr >500 pg/mL and interleukin-8 >20 pg/mL produced a screening test for sepsis with 94% sensitivity and 90% specificity. Conclusions: Our data show the utility of a rapid and sensitive assay for CTpr combined with interleukin-8 as a highly sensitive and specific diagnostic marker of bacterial sepsis in febrile, neutropenic children. The use of these markers as a clinical tool may allow for better prognostication for clinicians and may eventually lead to more targeted therapies for this heterogeneous population.

Neurological injury markers in children with septic shock.

Objective: To determine whether known serum markers of neurologic injury are increased in children with septic shock. Design: Prospective, observational study. Setting: Tertiary-care, pediatric intensive care unit. Patients: Two cohorts of children (n = 24) with septic shock were prospectively enrolled within 24 hrs of their diagnosis. In cohort 1, serum markers (S100&bgr;, neuron-specific enolase [NSE], and glial fibrillary acidic protein [GFAP]) were determined (n = 18). In cohort 2, in addition to serum markers, urine S100&bgr; and GFAP were determined, and continuous electroencephalography (cEEG) was performed. Children who presented to the emergency room with a fever served as controls (n = 32). Children with known neurologic conditions were excluded. Interventions: None. Measurements and Main Results: Serum and urine were collected daily for up to 7 days or until pediatric intensive care unit discharge. Biomarker concentrations were determined by commercially available enzyme-linked immunosorbent assays. cEEG was performed on days 1, 2, 4, and 7 in a 16-channel montage for at least 6 hrs. Physical examinations did not reveal focal neurologic deficits. Children with septic shock demonstrated increased serum S100&bgr; and NSE compared with controls (mean ± sem: 10.5 &mgr;g/L ± 2.4 vs. .9 &mgr;g/L ± .1, p < .001; 96.6 &mgr;g/L ± 8.9 vs. 4.0 &mgr;g/L ± 1.3, p < .001, respectively). Serum GFAP was detectable in five septic children and none of the controls. In cohort 2, urine of four patients demonstrated measurable S100&bgr; levels, and GFAP was detected in one child (nonsurvivor). cEEG demonstrated moderate to severe encephalopathy in all children studied. Conclusions: Markers of neurologic injuries are increased in children with septic shock. This may indicate subclinical injuries that are either transient or permanent. Studies that correlate the long-term neurologic outcome of children with these markers are needed to identify children at risk for neurologic injuries from septic shock.

Extracorporeal support in children with pediatric acute respiratory distress syndrome: proceedings from the Pediatric Acute Lung Injury Consensus Conference.

Objective: Extracorporeal life support has undergone a revolution in the past several years with the advent of new, miniaturized equipment and success in supporting patients with a variety of illnesses. Most experience has come with the use of extracorporeal membrane oxygenation, a modified form of cardiopulmonary bypass that can support the heart, lungs, and circulation for days to months at a time. To describe the recommendations for the use of extracorporeal membrane oxygenation in children with pediatric acute respiratory distress syndrome based on a review of the literature and expert opinion. Design: Consensus conference of experts in pediatric acute lung injury. Methods: A panel of 27 experts met over the course of 2 years to develop a taxonomy to define pediatric acute respiratory distress syndrome and to make recommendations regarding treatment and research priorities. The extracorporeal support subgroup comprised two international experts. When published data were lacking, a modified Delphi approach emphasizing strong professional agreement was used. Results: The Pediatric Acute Lung Injury Consensus Conference experts developed and voted on a total of 151 recommendations addressing the topics related to pediatric acute respiratory distress syndrome, 11 of which related to extracorporeal support. All recommendations had agreement, with 10 recommendations (91%) achieving strong agreement. These recommendations included the utilization of extracorporeal support for reversible causes of pediatric acute respiratory distress syndrome, consideration of quality of life when making the decision to use extracorporeal support, and the use of the Extracorporeal Life Support Organization registry to report all extracorporeal support activity, among others. Conclusions: Pediatric extracorporeal membrane oxygenation for pediatric acute respiratory distress syndrome could benefit from more specific data collection and collaboration of focused investigators to establish validated criteria for optimal application of extracorporeal membrane oxygenation and patient management protocols. Until that time, consensus opinion offers some insight into guidelines.

Pediatric trauma: Postinjury care in the pediatric intensive care unit

Traumatic injuries occur in >20 million children each year and are the leading source of death in children over the age of 1 yr. Mechanisms of injury and subsequent therapies for critically injured children are diverse. This review will focus on resources and management strategies for caring for the severely injured child in the pediatric intensive care unit.

Setup and maintenance of extracorporeal life support programs.

Setting up an extracorporeal life support program requires motivated experts, institutional commitment, and an interprofessional team of healthcare providers with dedicated time, space, and resources. This article provides guidance on the key steps involved in the process of developing a sustainable extracorporeal membrane oxygenation program, based on guidelines from the Extracorporeal Life Support Organization and from an international perspective.

Propofol Anesthesia for Elective Cardioversion of Pediatric Intensive Care Unit Patients with Congenital Heart Disease

Propofol is an intravenous sedative-hypnotic anesthetic agent that has been increasingly employed to facilitate elective direct current cardioversion in adult patients. Little information is available about use of propofol in pediatric intensive care unit patients with congenital heart disease undergoing elective cardioversion. We report our experience with 33 cardioversions performed in our pediatric intensive care unit using propofol anesthesia. Propofol provided good subjective conditions for cardioversion in all patients, and 97% of cardioversions successfully converted atrial flutter into a sinus rhythm. Mean induction time was 5.97 ± 3.54 minutes, and recovery time was 28.08 ± 22.88 minutes. Length of stay in the pediatric intensive care unit was 3.84 ± 1.20 hours. Transient hypotension occurred during 24% of cardioversions, whereas brief periods of respiratory depression were present during 30% of cardioversions. Propofol anesthesia can be successfully administered during elective cardioversion in pediatric intensive care unit patients with congenital heart disease provided that appropriate cardiorespiratory monitoring and supportive therapies are in place.

The use of a mobile computed tomography scanner in the pediatric intensive care unit to evaluate airway stenting and lung volumes with varying levels of positive end-expiratory pressure.

Objective Presentation of a case report describing the use of a mobile computed tomography (CT) scanner in the pediatric intensive care unit (PICU) to radiographically evaluate tracheobronchial stenting and lung volumes while using different levels of positive end-expiratory pressure (PEEP) and positioning in a critically ill infant. Design Case report of a single patient. Setting Pediatric intensive care unit in a University Hospital. Patient A 6-month-old premature infant with bronchopulmonary dysplasia, tracheobronchomalacia, and progressive respiratory failure. Interventions CT scans of the chest were performed by using a mobile CT scanner in the PICU. Serial CT scans were performed at PEEP levels of 5, 10, 15, and 20 cm H2O in both the supine and prone position. Scheduled medical care and standard monitoring were continued during the course of the CT scans. Measurements and Main Results Identical anatomic levels demonstrating the trachea, bronchi, and lung parenchyma were compared while different levels of PEEP and supine or prone positioning were used. From these comparisons, the level of PEEP in which lung volumes were optimized was radiographically determined. No significant changes in large airway caliber were observed. There was no difference noted between prone and supine positioning. CT scans were completed with minimal disruption to the patient’s care. Conclusions Mobile CT scanners can be used in the PICU for the diagnostic evaluation of critically ill children. This option allows for the continuation of medical therapies and monitoring in the intensive care setting while avoiding the potential complications of transporting a critically ill child to the radiology department. The use of mobile CT scanners may disrupt PICU routine and is more expensive than use of fixed CT scanners. Mobile CT scanners may be useful in radiographically determining the optimal level of PEEP in infants with tracheobronchomalacia and bronchopulmonary dysplasia.

Pulmonary arterial endothelial dysfunction potentiates hypercapnic vasoconstriction and alters the response to inhaled nitric oxide.

BACKGROUND Pulmonary hypertensive crisis can be initiated by episodes of hypercapnic acidosis. Hypercapnic vasoconstriction in the newborn pulmonary arterial circulation may be modulated by endogenous production of nitric oxide (NO) by the endothelial cell and effectively treated with inhalation of NO. METHODS Sixteen 48-hour-old piglets were randomized to receive a hypercapnic challenge after administration of either saline vehicle or the NO synthase inhibitor N-omega-nitro-L-arginine (L-NA). Pulmonary arterial pressure, flow, and radius measurements were taken at baseline, after infusion of vehicle or L-NA, during hypercapnia (inspired fraction of carbon dioxide, 0.15), and during inhalation of NO (100 ppm). Fourier analysis was used to calculate input mean impedance, reflecting distal arteriolar vasoconstriction, and characteristic impedance, reflecting proximal arterial geometry and distensibility. RESULTS Input mean impedance was increased with L-NA administration. Animals pretreated with L-NA also underwent a much larger increase in input mean impedance with exposure to hypercapnia than untreated animals. Characteristic impedance increased in the treated animals, but not in the controls. CONCLUSIONS In the newborn pulmonary arterial circulation, endogenous NO production by the endothelial cell modulates resting tone distally, but not proximally. In addition, lack of a functional endothelium markedly potentiates the distal vasoconstrictor response to hypercapnia and produces proximal vasoconstriction. Despite impaired endothelial function, inhaled NO remains an effective vasodilator in hypercapnic pulmonary vasoconstriction.