Resource use and health outcomes of paediatric extracorporeal membrane oxygenation.

The use of extracorporeal membrane oxygenation can be rationalised by the assumption that non-zero survival after refractory cardiorespiratory failure represents improved outcome. Survivors may have cognitive and or functional morbidities, require complex ongoing care, and as a consequence consume considerable healthcare resources.

Severe acute asthma in a pediatric intensive care unit: six years' experience.

The management of children with severe acute asthma who required admission to the intensive care (ICU) of this hospital during 1982 to 1988 was reviewed retrospectively. A total of 89 children were admitted to the ICU on 125 occasions. During the study period, 24% of the patients were admitted to the ICU on more than one occasion. Prior to admission to this hospital, patients had been symptomatic for a mean of 48 hours. Although all patients had received bronchodilators before admission to hospital, only 23% of patients had received oral corticosteroids. According to initial arterial blood gas values determined in the ICU, 77% of the patients had hypercapnia (PaCO2 greater than 45 mm Hg). The pharmacologic agents used in the ICU included nebulized beta 2-agonists (100% of admissions), theophylline (99%), steroids (94%), nebulized ipratropium bromide (10%), IV albuterol (38%), and IV isoproterenol (10%). Mechanical ventilation was necessary in 33% of admissions; the mean duration of ventilation was 32 hours. Ten patients had pneumothorax; in six cases, these were related to mechanical ventilation. Three of the patients who received mechanical ventilation died, representing a mortality of 7.5%. In each of these patients, sudden, severe asthma episodes had developed at home, resulting in respiratory arrest. They had evidence of hypoxic encephalopathy at the time of admission to the ICU and eventually were declared brain dead. It was concluded that delay in seeking medical care and underuse of oral corticosteroids at home may have contributed to the need for ICU admission.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous arteriovenous hemofiltration after cardiac operations in infants and children.

Acute renal insufficiency after cardiopulmonary bypass can lead to a significant morbidity from fluid overload and electrolyte disturbance, impede pulmonary gas exchange, and postpone weaning from mechanical ventilation. The limitations placed on free water intake result in severe restriction of nutrition while diuretic therapy causes electrolyte imbalance. Artificial renal support either in the form of peritoneal dialysis or hemodialysis may be complicated by sepsis and hemodynamic instability. We reviewed our experience with the use of continuous arteriovenous hemofiltration, an extracorporeal technique for removal of solutes, toxins, and water in critically ill patients with cardiac failure complicated by acute renal insufficiency and hemodynamic instability after cardiopulmonary bypass. Ten infants and children with renal insufficiency caused by low cardiac output had continuous arteriovenous hemofiltration instituted for indications including sepsis, volume overload, oliguria for more than 24 hours nonresponsive to diuretic therapy, and the need for hyperalimentation. All were supported by mechanical ventilation and receiving high-dose inotropic support. Arterial and venous vascular access was successfully obtained by cannulation of the femoral artery and vein in nine patients. Anticoagulation of the circuit was achieved with heparin infusion (6 to 20 micrograms/kg/hr) and monitored by measurement of activated clotting time. The continuous arteriovenous hemofiltration circuit was replaced if there was clot formation, or at 3 days after placement. Dialysis solution (Dianeal) 1.5% or 0.5% was infused as prefilter dilution. With the use of continuous arteriovenous hemofiltration, 20 to 100 m/hr of ultrafiltrate was removed, which allowed correction of hypervolemia, and caloric intake increased from 13.5 kcal/kg/day to 79.5 kcal/kg/day. Continuous arteriovenous hemofiltration was maintained between 5 hours and 8 days and was well tolerated in all patients. Serum urea and creatinine levels declined during continuous arteriovenous hemofiltration. We conclude that continuous arteriovenous hemofiltration is a safe and effective method for fluid and electrolyte homeostasis and that it thus allows hyperalimentation in infants and children after cardiac operations.

Mechanical circulatory support for the treatment of children with acute fulminant myocarditis.

BACKGROUND: Viral myocarditis may follow a rapidly progressive and fatal course in children. Mechanical circulatory support may be a life-saving measure by allowing an interval for return of native ventricular function in the majority of these patients or by providing a bridge to transplantation in the remainder. METHODS: A retrospective chart review of 15 children with viral myocarditis supported with extracorporeal membrane oxygenation (12 patients) or ventricular assist devices (3 patients) was performed. RESULTS: All patients had histories and clinical findings consistent with acute myocarditis. The median age was 4.6 years (range 1 day-13.6 years) with a median duration of mechanical circulatory support of 140 hours (range 48-400 hours). Myocardial biopsy tissue demonstrated inflammatory infiltrates or necrosis, or both, in 8 (67%) of the 12 patients who had biopsies. Overall survival was 12 (80%) of 15 patients, with 10 (83%) survivors of extracorporeal membrane oxygenation and 2 (67%) survivors of ventricular assist device support. Nine (60%) of the 15 patients were weaned from support, with 7 (78%) survivors; the remaining 6 patients were successfully bridged to transplantation, with 5 (83%) survivors. All survivors not undergoing transplantation are currently alive with normal ventricular function after a median follow-up of 1.1 years (range 0.9-5.3 years). CONCLUSION: Eighty-percent of the children who required mechanical circulatory support for acute myocarditis survived in this series. Recovery of native ventricular function to allow weaning from support can be anticipated in many of these patients with excellent prospects for eventual recovery of full myocardial function.

The effect of single-dose and continuous skeletal muscle paralysis on respiratory system compliance in paediatric intensive care patients.

OBJECTIVE: To investigate the effect of single dose and continuous skeletal muscle paralysis on respiratory system compliance in 53 paediatric intensive care patients. DESIGN: Prospective clinical study. SETTING: Multidisciplinary paediatric intensive care unit. PATIENTS: Twenty-three children ventilated for acute pulmonary pathology, and 30 ventilated for isolated intracranial pathology, who initially had normal lungs. INTERVENTIONS: The 23 patients with acute pulmonary pathology received a single dose of muscle relaxant to facilitate diagnostic procedures. Fifteen patients with isolated intracranial pathology received continuous skeletal muscle paralysis for longer than 24 h, and the other 15 received no paralysis. MEASUREMENTS AND RESULTS: Respiratory system compliance deteriorated by 14% from 0.519 +/- 0.2 to 0.445 +/- 0.18 ml cmH2O-1 kg-1 (p < 0.001) following a single dose of muscle relaxant in the 23 patients with acute pulmonary pathology. In the 15 with isolated intracranial pathology who received continuous skeletal muscle paralysis there was a progressive deterioration in compliance, which reached 50% of the initial compliance by day 4 of paralysis (p < 0.001) and improved back to normal following discontinuation of paralysis. There were no changes in compliance in the 15 patients with isolated intracranial pathology who were ventilated but not paralysed. The paralysed patients required mechanical ventilation longer than the non-paralysed patients (p < 0.001), and 26% of these patients developed nosocomial pneumonia (p = 0.03), a complication that was not seen in the non-paralysed patients. CONCLUSIONS: Skeletal muscle paralysis results in immediate and progressive deterioration of respiratory system compliance and increased incidence of nosocomial pneumonia. The benefits of paralysis should be balanced against the risks of deteriorating pulmonary function.

Influence of perioperative factors on outcomes in children younger than 18 months after repair of tetralogy of Fallot.

BACKGROUND: There has been a trend toward advocating earlier repair of tetralogy of Fallot and avoiding palliative procedures. The impact of this trend on perioperative outcomes has not been adequately documented. METHODS: Data from consecutive patients undergoing repair of tetralogy of Fallot at less than 18 months of age from May 1987 to September 1994 were reviewed. Independent factors associated with duration of stay in the intensive care unit were sought. RESULTS: Repair was performed in 89 infants at a median age of 13 months (range, 15 days to 18 months). A systemic-pulmonary artery shunt was present in 24% of patients. Mean duration of cardiopulmonary bypass was 119+/-37 minutes; 63% of patients received a transannular patch. There were six deaths (7%), all occurring less than 48 hours after repair. The median duration of stay in the intensive care unit was 5 days (range, 1 day to 8 months). Significant independent factors associated with increasing length of intensive care unit stay included younger age at repair, previous shunt, malformation syndrome, increased total dose and number of inotropic agents used, and respiratory complications. Hemodynamic variables serially recorded in the first 48 hours after repair were independently associated with death or prolonged (>7 days) duration of stay. CONCLUSIONS: Although outcomes after repair of tetralogy of Fallot in infants are good, both younger age at repair and previous palliative procedures were associated with longer duration of stay in the intensive care unit.

Clinical outcomes of acute myocarditis in childhood.

OBJECTIVE: To describe clinical outcomes of a paediatric population with histologically confirmed lymphocytic myocarditis. DESIGN: A retrospective review between November 1984 and February 1998. SETTING: A major paediatric tertiary care hospital. PATIENTS: 36 patients with histologically confirmed lymphocytic myocarditis. MAIN OUTCOME MEASURES: Survival, cardiac transplantation, recovery of ventricular function, and persistence of dysrhythmias. RESULTS: Freedom from death or cardiac transplantation was 86% at one month and 79% after two years. Five deaths occurred within 72 hours of admission, and one late death at 1.9 years. Extracorporeal membrane oxygenation support was used in four patients, and three patients underwent heart replacement. 34 patients were treated with intravenous corticosteroids. In the survivor/non-cardiac transplantation group (n = 29), the median follow up was 19 months (range 1.2-131.6 months), and the median period for recovery of a left ventricular ejection fraction to > 55% was 2.8 months (range 0-28 months). The mean (SD) final left ventricular ejection and shortening fractions were 66 (9)% and 34 (8)%, respectively. Two patients had residual ventricular dysfunction. No patient required antiarrhythmic treatment. All survivors reported no cardiac symptoms or restrictions in physical activity. CONCLUSIONS: Our experience documents good outcomes in paediatric patients presenting with acute heart failure secondary to acute lymphocytic myocarditis treated with immunosuppression. Excellent survival and recovery of ventricular function, with the absence of significant arrhythmias, continued cardiac medications, or restrictions in physical activity were the normal outcomes.

Efficacy, results, and complications of mechanical ventilation in children with status asthmaticus.

We have conducted a retrospective survey of 79 children out of a total hospital asthmatic patient population of 2,412, admitted over a 32 month period to the ICU for the management of severe status asthmaticus. All patients were in severe respiratory distress with CO2 retention; 19 required mechanical ventilation due to increasing fatigue and worsening bronchospasm, having failed to respond to either inhaled or IV bronchodilator therapy. All patients were ventilated at slow rates (less than 12 min) and their airway pressure (Paw) was deliberately kept below 45 cmH2O, while accepting a PaCO2 in the 45-60 mmHg range, as long as the pH was compensated. Although two patients developed pneumothoraces while on positive pressure ventilation, these were resolved without incidents. Five patients who had mediastinal or subcutaneous air leaks prior to intubation did not develop pneumothoraces. Following the initiation of mechanical ventilation, IV beta-agonist therapy was increased in order to reverse the bronchospasm and reduce the duration of mechanical ventilation. Mean duration of intubation was 42 hours. Fourteen of the 19 patients were weaned and extubated within 48 hours. All patients survived without sequelae. We conclude that a degree of controlled "hypoventilation" by deliberately choosing Paw less than 45 cmH2O can be successfully used to ventilate children with severe status asthmaticus with a reduced rate of pressure-related complications.

The use of inotropic and afterload-reducing agents in neonates.

Vasodilators have demonstrated efficacy in neonates with depressed myocardial function. The magnitude of benefit depends on the preexisting hemodynamic state and concurrent treatment modalities. In patients with increased filling pressures, vasodilators increase cardiac output with negligible effect on MAP, with volume resuscitation to restore pretreatment filling pressures offering additional benefit. The rationale for use in neonatal respiratory disease remains less clear, with no vasoactive drug showing selective pulmonary vasodilatation. Benefit no doubt accrues from the improved coronary perfusion that occurs with reduction in filling pressures. In addition, reduced interventricular diastolic dependence and thereby improved ventricular compliance, as well as the afterload-reducing effect of decreased chamber size, may significantly reduce the effect of the lung disease on myocardial functioning.

Postnatal management of congenital diaphragmatic hernia.

The emphasis in postnatal management has shifted from the neonatal surgical emergency approach to strategies designed to deal with pulmonary hypoplasia and the pulmonary vascular abnormalities. There has been extensive experience with alternative ventilation strategies such as ECMO and high frequency ventilation, without there being convincing evidence that these have had a major impact on mortality. Strategies that emphasize the importance of minimizing ongoing lung injury, such as pressure limited (permissive hypercapnia) ventilation and the use of surfactant replacement therapy, are beginning to show some encouraging results.

Negative pressure ventilation via chest cuirass to decrease ventilator-associated complications in infants with acute respiratory failure: a case series.

Pulmonary and nonpulmonary complications of invasive positive pressure ventilation are well documented in the medical literature. Many of these complications may be minimized by the use of noninvasive ventilation. During various periods of medical history, negative pressure ventilation, a form of noninvasive ventilation, has been used successfully. We report the use of negative pressure ventilation with a chest cuirass to avoid or decrease the complications of invasive positive pressure ventilation in three critically ill infants at two institutions. In each of these cases, chest cuirass ventilation improved the patient's clinical condition and decreased the requirement for more invasive therapy. These cases illustrate the need for further clinical evaluation of the use of negative pressure ventilation utilizing a chest cuirass.

Unsuspected diaphragmatic hernia: a potential cause of sudden and unexpected death in infancy and early childhood.

Congenital diaphragmatic hernias are usually found in neonates who present with respiratory distress. However, a significant number may remain clinically undiagnosed until much later in life. Of interest, the prognosis is felt to be better in this latter group. We describe three previously well patients (aged 2, 4, and 24 months) who suffered unexpected cardiorespiratory arrests due to unsuspected congenital diaphragmatic defects with intestinal herniation. Deaths resulted from cardiovascular and respiratory compromise due to visceral herniation that caused mediastinal and pulmonary compression.

Fatal bicycle accidents in children: a plea for prevention.

We reviewed the coroner's records of all fatal bicycle accidents occurring in children (aged 0 to 15 years) in Ontario (pediatric population, 2,007,230) between January 1, 1985 and December 31, 1989. The injuries sustained were documented and scored with anatomical injury scores (Abbreviated Injury Score 1985 and Injury Severity Score) and categorized as unsurvivable or survivable. The causes and circumstances were documented from police accident reports. Eighty-one deaths resulted from bicycle accidents, an annual mortality rate of 1.44 deaths per 100,000 children per year. In 74 (91%) of these cases the injuries were deemed unsurvivable, 89% of which were head injuries. Seventy-eight (96%) of the deaths resulted from collisions with motor vehicles. No victim was wearing a helmet at the time of injury. In 70% of the deaths, the cyclist was considered to have caused the collision, either because of a violation of a road traffic law or poor road sense. These findings suggest that more emphasis should be placed on primary and secondary injury prevention by such methods as bicycle safety education for children and the promotion of bike helmet use. In addition, in view of the high incidence of unsurvivable head injury, the introduction of legislation requiring the use of protective helmets should be considered.

The relationship between PaCO2 and ventilation parameters in predicting survival in congenital diaphragmatic hernia.

Fifty-eight infants with congenital diaphragmatic hernia presenting within the first 6 hours of life, who underwent surgical repair, were analysed prospectively in order to produce a reliable index of severity of disease that would reliably predict eventual outcome. All were treated with paralysis hyperventilation and intravenous (IV) isoproterenol for the first 48 hours. There were 30 survivors and 28 deaths in this series (mortality 48%). Using arterial PCO2 values measured 2 hours after surgical repair and correlating them with an index of mechanical ventilation (mean airway pressure and respiratory rate), we have been able to clearly define two groups of diaphragmatic hernia based on their response to IPPV. The first group, with CO2 retention and severe preductal shunting, was unresponsive to hyperventilation with high rates and pressures; the mortality was 90%. The second group responded well to hyperventilation and demonstrated reversable ductal shunting only. Survival in this group was 97%. Only four patients out of 58 exhibited the "honeymoon period," with a period of stability followed by severe ductal shunting. Arterial CO2 accurately reflects the degree of lung development in this disease and separates those patients with severe pulmonary hypoplasia, where the outcome is invariably fatal, from those with a well-developed contralateral lung where there is excellent potential for survival.

Preventable pediatric trauma deaths in a metropolitan region.

All pediatric trauma deaths occurring in metropolitan Toronto (population, 2.2 million) in 1986 were analyzed from the regional coroner's records. Injuries sustained were scored using the Abbreviated Injury Scale (1985; AIS) and Injury Severity Score (ISS). Victims with injuries graded AIS 6 (any region), AIS 5 head/neck (excluding acute epidural hematoma), or ISS greater than 59 were deemed unsalvageable. All other injuries were considered survivable and the deaths from them preventable. Use of these objective criteria indicated that 8/38 of the children (21%) who died from trauma had survivable injuries. Since in three cases medical aid was not sought because of social circumstances, 5/38 (13%) was considered a realistic estimate of preventable death rate (PDR). These results suggest that when objective criteria are used, the PDR in pediatric trauma may be less than that reported in adult trauma victims. Defining the PDR on the basis of objective criteria may prove useful in the conduct of further studies of this kind and permit valid comparisons to be made.

Timing of surgery for congenital diaphragmatic hernia: is emergency operation necessary?

Congenital diaphragmatic hernia (CDH) is considered by most researchers to be a surgical emergency. However, early repair does not necessarily improve respiratory function or reverse fetal circulation, and many patients deteriorate postoperatively. As a result, in 1985, we began to employ a protocol in which surgery was delayed until the PCO2 was maintained below 40 and the child was hemodynamically stable; children in whom these criteria could not be achieved died without surgical repair. Sixty-one consecutive infants with CDH were managed over 4 years; 31 from 1983 to 1984 (group 1) and 30 from 1985 to 1986 (group 2). The groups were similar with respect to sex, side of the defect, birth weight, gestational age, incidence of pneumothorax, and blood gases. High frequency oscillation was used with increasing frequency during the study period, for patients with refractory hypercarbia (13% in group 1, 30% in group 2). All patients were initially paralyzed and ventilated. Mean time from admission to surgery was 4.1 hours in group 1 and 24.4 hours in group 2 (P less than .05). In group 1, 87% of patients had surgical repair (77% within eight hours of admission, 10% after eight hours), and in group 2 only 70% of patients had surgery (10% within eight hours, 60% after eight hours). All patients who were not operated on died. Overall mortality was 58% in group 1 and 50% in group 2; this difference was not statistically significant. These data indicate that our current approach has not increased overall mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hypothermia and cardiac arrest on outcome of near-drowning accidents in children.

We conducted a retrospective review of 55 near-drowning victims (mean age 4.75 years) admitted to the intensive care unit during a 5-year period, to determine the factors that may influence survival both before and after hospital admission. All patients who remained comatose after resuscitation received ventilation for an initial 24 hour period, after which an assessment of central nervous system injury was made. Intracranial pressure was not monitored, and barbiturate therapy was used only for seizure control. Thirty-seven children survived and 18 died; five survivors had profound neurologic damage resulting in a persistent vegetative state: the remaining 32 (58%) survived intact. The major factors that separated intact survivors from those who died and from survivors in a persistent vegetative state were the presence of a detectable heartbeat and hypothermia (less than 33 degrees C) on examination in the emergency department. Thirteen patients with absent vital signs and a temperature of greater than 33 degrees C either died or survived in a persistent vegetative state. Fourteen patients had a combination of absent vital signs and hypothermia and were resuscitated; eight died, two survived in a persistent vegetative state, and four survived intact. All intact survivors had been submerged in cold water for prolonged periods, and all underwent prolonged cardiopulmonary resuscitation. All patients with a detectable pulse, regardless of temperature, survived without neurologic sequelae. The 58% intact survival rate in this series compares favorably with the 50% we reported previously when high-dose barbiturate therapy and hypothermia were used to control intracranial pressure; at the same time, the number of survivors with a persistent vegetative state has been reduced by 50%. We conclude that prolonged in-hospital resuscitation and aggressive treatment of near-drowning victims who initially have absence of vital signs and are not hypothermic either results in eventual death or increases the number of survivors with a persistent vegetative state.

Neutrophil migration in vitro and in vivo during hypothermia.

The effect of hypothermia on pig leukocyte migration in vitro and in vivo was studied. Neutrophil chemotaxis in vitro under agarose was significantly impaired at 29 degrees C (2.7 +/- 0.6 [mean +/- standard error]; 37 degrees C, 7.1 +/- 1.1). Leukocytes isolated from hypothermic pigs and tested at 37 degrees C migrated normally (7.8 +/- 0.6). Neutrophil and monocyte migration in vivo was markedly reduced at 29 degrees C. Reduced inflammatory responses may contribute to increased infections during hypothermia.

Pulse oximetry in pediatric intensive care: comparison with measured saturations and transcutaneous oxygen tension.

We evaluated a new pulse oximeter designed to monitor beat-to-beat arterial oxygen saturation (SaO2) and compared the monitored SaO2 with arterial samples measured by co-oximetry. In 40 critically ill children (112 data sets) with a mean age of 3.9 years (range 1 day to 19 years), SaO2 ranged from 57% to 100%, and PaO2 from 27 to 128 mm Hg, heart rates from 85 to 210 beats per minute, hematocrit from 20% to 67%, and fetal hemoglobin levels from 1.3% to 60%; peripheral temperatures varied between 26.5 degrees and 36.5 degrees C. Linear correlation analysis revealed a good agreement between simultaneous pulse oximeter values and both directly measured SaO2 (r = 0.95) and that calculated from measured arterial PaO2 (r = 0.95). The device detected several otherwise unrecognized drops in SaO2 but failed to function in four patients with poor peripheral perfusion secondary to low cardiac output. Simultaneous measurements with a tcPO2 electrode showed a similarly good correlation with PaO22 (r = 0.91), but the differences between the two measurements were much wider (mean 7.1 +/- 10.3 mm Hg, range -14 to +49 mm Hg) than the differences between pulse oximeter SaO2 and measured SaO2 (1.5% +/- 3.5%, range -7.5% to -9%) and were not predictable. We conclude that pulse oximetry is a reliable and accurate noninvasive device for measuring saturation, which because of its rapid response time may be an important advance in monitoring changes in oxygenation and guiding oxygen therapy.