Occult risk factor for the development of cerebral edema in children with diabetic ketoacidosis: possible role for stomach emptying.

The incidence of cerebral edema during therapy of diabetic ketoacidosis (DKA) in children remains unacceptably high-this suggests that current treatment may not be ideal and that important risk factors for the development of cerebral edema have not been recognized. We suggest that there are two major sources for an occult generation of osmole-free water in these patients: first, fluid with a low concentration of electrolytes that was retained in the lumen of the stomach when the patient arrived in hospital; second, infusion of glucose in water at a time when this solution can be converted into water with little glucose. In a retrospective chart review of 30 patients who were admitted with a diagnosis of DKA and a blood sugar > 900 mg/dL (50 mmol/L), there were clues to suggest that some of the retained fluid in the stomach was absorbed. To minimize the likelihood of creating a dangerous degree of cerebral edema in patients with DKA, it is important to define the likely composition of fluid retained in the stomach on admission, to look for signs of absorption of some of this fluid during therapy, and to be especially vigilant once fat-derived brain fuels have disappeared, because this is the time when glucose oxidation in the brain should increase markedly, generating osmole-free water.

A hyperglycaemic hyperosmolar state in a young child: diagnostic insights from a quantitative analysis.

This teaching exercise demonstrates how the application of principles of physiology can identify the cause of a severe degree of hyperglycaemia (plasma glucose concentration 80 mmol/l) in a very young patient with newly diagnosed diabetes mellitus, determine whether the patient has diabetic ketoacidosis, and highlight the potential risks for this patient on admission and during initial therapy. A consultation with Professor McCance was sought to determine whether this patient had an unusual degree of 'insulin resistance'. There were also uncertainties regarding the acid-base diagnosis. The patient did not appear to have an important degree of metabolic acidosis as judged from his pH of 7.39 and plasma bicarbonate concentration of 20 mmol/l in arterial blood; hence the diagnostic impression was that he had a hyperglycaemic hyperosmolar state. However, his plasma anion gap was significantly elevated, and remained so for 60 h, despite the administration of insulin. Issues in management concerning the basis for this severe degree of hyperglycaemia and how to minimize the risk of developing cerebral oedema are addressed. The missing links in this interesting story emerge during a discussion between the medical team and their mentor, Professor McCance.

Uncovering the basis of a severe degree of acidemia in a patient with diabetic ketoacidosis.

In this teaching exercise, the goal is to demonstrate how an application of principles of physiology can reveal the basis for a severe degree of acidaemia (pH 6.81, bicarbonate <3 mmol/l (P(HCO(3))), PCO(2) 8 mmHg), why it was tolerated for a long period of time, and the issues for its therapy in an 8-year-old female with diabetic ketoacidosis. The relatively low value for the anion gap in plasma (19 mEq/l) suggested that its cause was both a direct and an indirect loss of NaHCO(3). Professor McCance suggested that ileus due to hypokalaemia might cause this direct loss of NaHCO(3), and that an excessive excretion of ketoacid anions without NH(4)(+) in the urine accounted for the indirect loss of NaHCO(3). In addition, he suspected that another factor also contributing to the severity of the acidaemia was a low input of alkali. He was also able to explain why there was a 16-h delay before there was a rise in the P(HCO(3)) once therapy began. The missing links in this interesting story, including a possible basis for the hypokalaemia, emerge during the discussion between the medical team and Professor McCance.

Acute and fatal hyponatraemia after resection of a craniopharyngioma: a preventable tragedy.

Central diabetes insipidus developed for the first time in a 14-year-old female during the resection of a craniopharyngioma. The water diuresis persisted until a vasopressin analogue (dDAVP) was given. Professor McCance was asked to explain why hypernatraemia developed, to anticipate dangers that might develop in the salt and water area with therapy, and to provide insights into why this patient died, due to the subsequent development of hyponatraemia that caused a lethal rise in intracranial pressure. The team specifically wanted Professor McCance's opinions as to why a PNa of 124 mmol/l was uniquely dangerous for this patient, and this was a particularly challenging conundrum. Nevertheless, with the aid of a mini-experiment, a careful chart review, and creative thinking, he was able to offer a novel solution, and to suggest ways to prevent its occurrence in other patients.

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)

Determinants of prognosis in idiopathic dilated cardiomyopathy as determined by programmed electrical stimulation.

The incidence and prognostic significance of electrically induced ventricular arrhythmias were prospectively assessed in 42 patients with idiopathic dilated cardiomyopathy. All patients underwent 24-hour, long-term electrocardiographic (Holter) monitoring and 30 were analyzed by a signal-averaging vectorcardiographic procedure at entry into the study. Their response to programmed electrical stimulation during basic right ventricular pacing was investigated using 1 and 2 ventricular extrastimuli. A monomorphic tachycardia was not induced in any patient. In 36 patients (86%) polymorphic ventricular arrhythmias were initiated. Three or more induced consecutive ventricular premature complexes occurred in 9 patients (21%), nonsustained polymorphic ventricular tachycardia in 2 (4.8%) and ventricular fibrillation in 1 patient (2.4%). There was no association between electrically induced polymorphic ventricular arrhythmias and the degree of impairment of left ventricular function. Furthermore, the incidence of induced ventricular arrhythmias was not related to the Lown grade or to the total number of ventricular premature complexes during Holter monitoring. A late potential was detected by the averaged vectorcardiogram in only 1 of the 30 patients. During follow-up (mean 16 +/- 7 months) 7 patients died, 5 from chronic congestive heart failure and 2 from sudden cardiac death. No patient had an electrically induced arrhythmia of 3 or more ventricular premature complexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal replacement therapy after repair of congenital heart disease in children. A comparison of hemofiltration and peritoneal dialysis.

The development of renal failure necessitating peritoneal dialysis after cardiac operations is associated with a reported mortality greater than 50%. Improved fluid removal and nutritional support have been reported with the use of continuous arteriovenous hemofiltration and continuous venovenous hemofiltration techniques. We have compared our experience with all three techniques in managing children who required renal replacement therapy after cardiac operations in terms of efficacy (fluid removal, calorie intake, and clearance of urea and creatinine), complications, and outcome. Over a 5-year period renal replacement therapy was initiated in 42 children, and in 34 of them it was successfully established for more than a 24-hour period: 17 were managed with peritoneal dialysis, 8 with continuous arteriovenous hemofiltration, and 9 with continuous venovenous hemofiltration. A net negative fluid balance was achieved in only 6 (35%) patients treated with peritoneal dialysis compared with 50% of those treated with continuous venovenous hemofiltration and 89% of those treated with continuous venovenous hemofiltration. In terms of nutritional support, calorie intake increased by 43% after peritoneal dialysis was started compared with 515% and 409% in the arteriovenous and venovenous hemofiltration groups, respectively, (p < 0.005). The serum urea levels fell by 36% (p = 0.02) and 39% (p = 0.005) compared with pre-therapy levels with arteriovenous and venovenous hemofiltration, respectively, and the creatinine content was reduced by 19% and 33% (p = 0.003). Neither parameter was reduced in the peritoneal dialysis group. We conclude that the use of hemofiltration as a renal replacement therapy after surgical correction of congenital heart disease offers significant advantages over the more traditional approach of peritoneal dialysis. In addition, we suggest that a more aggressive approach to the management of fluid overload and nutritional depletion with hemofiltration may result in a decrease in the very high mortality seen in renal failure after cardiac operations.

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.

Evaluation of a new method of detection of nosocomial infection in the pediatric intensive care unit: the Infection Control Sentinel Sheet System.

To improve the efficiency of nosocomial infection detection, a highly structured system combining initial reporting by the bedside night nurse of symptoms possibly related to infection with follow-up by the infection control nurse (ICN) was developed: The Infection Control Sentinel Sheet System (ICSSS). Between July 1, 1987 and February 28, 1988, a prospective comparison of results obtained through ICSSS and daily bedside observation/chart review by a full-time trained intensivist was undertaken in the pediatric intensive care unit (PICU). Ratios of nosocomial infections and nosocomially-infected patients were 15.8 and 7.0 respectively among 685 admissions; included are seven infections identified only through the ICSSS so that the "gold standard" became an amalgamation of the two systems. The sensitivity for detection of nosocomially-infected patients by bedside observation/chart review and ICSSS was 100% and 87% respectively. The sensitivity for detection of standard infections (blood, wound and urine) was 88% and 85% respectively. The sensitivity for detection of nosocomial infections at all sites was 94% and 72% respectively. Missed infections were minor (e.g., drain, skin, eye), required physician diagnosis (e.g., pneumonia), were not requested on the sentinel sheet (SS) (e.g., otitis media), related to follow-up of deceased patients or were minor misclassifications or failures to associate with device (e.g., central-line related). Daily PICU surveillance by the ICN required only 20 minutes a day. The ICSSS appears highly promising and has many unmeasured benefits.

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.

Inhaled nitric oxide differentiates pulmonary vasospasm from vascular obstruction after surgery for congenital heart disease.

OBJECTIVE: To evaluate whether a trial of inhaled nitric oxide (NO) differentiates reversible pulmonary vasoconstriction from fixed anatomic obstruction to pulmonary blood flow after surgery for congenital heart disease in patients at risk for pulmonary hypertension. DESIGN: Prospective cohort study. SETTING: Tertiary care children's hospital. PATIENTS: 15 neonate and infants with elevated pulmonary artery or right ventricular pressure or with clinical signs suggestive of high pulmonary vascular resistance in the early postoperative period following repair of congenital heart disease. INTERVENTION: 30-min trial of 40 ppm inhaled NO. RESULTS: 5 patients responded to inhaled NO, 2 patients were weaned from extracorporeal support with NO. Four were maintained on continuous inhaled NO for 3 to 5 days. All the responders survived. Ten patients did not respond to NO. An important anatomic obstruction was found with echocardiography or angiography in all 10 patients. Reintervention was performed in 6/10 (4 stent placement, 1 balloon angioplasty of pulmonary arteries and 1 revision of systemic to pulmonary shunt). Six of the nonresponders died. CONCLUSION: A trial of inhaled NO after cardiac surgery in neonates and infants may be useful to differentiate reversible pulmonary vasoconstriction from fixed anatomic obstruction and may provide useful information if temporary support with extracorporeal membrane oxygenation is considered. Failure to respond to inhaled NO should prompt further investigations to rule out a residual obstruction.

Tonicity balance, and not electrolyte-free water calculations, more accurately guides therapy for acute changes in natremia.

The usual way to decide why hyponatremia or hypernatremia has developed and to plan goals for its therapy is to analyze events in electrolyte-free water (EFW) terms. We shall demonstrate that an EFW balance does not supply this information. Rather, one must calculate mass balances for water and sodium plus potassium separately (a tonicity balance) to understand the basis for the change in natremia and the proper goals for its therapy. These points are illustrated with a clinical example.

Intensive care management of paediatric organ donors and its effect on post-transplant organ function.

OBJECTIVES: 1. To document the clinical course of paediatric beating heart organ donors. 2. To evaluate the effect of the ICU management of pediatric donors on the immediate function of transplanted organs. 3. To examine the validity of current donor selection criteria. DESIGN: Retrospective chart review and case series study. SETTING: Multidisciplinary ICU of tertiary referral paediatric hospital. PATIENTS: All patients who became solid organ donors between January 1980 and July 1990. OUTCOME MEASURES: 1. Incidence of major physiological abnormalities of the cardiovascular, pulmonary, renal and metabolic systems. 2. Number of organs retrieved and transplanted, reasons for non-transplantation of donated organs. 3. Immediate post-transplant function of transplanted organs. RESULTS: Seventy-seven organ donors were identified from whom 134 kidneys, 31 livers and 12 hearts were transplanted. Sixty (78%) patients developed diabetes insipidus. Sustained hypotension occurred in 41 (53.2%) and was commoner in patients treated with inotropic agents in the presence of a low central venous pressure and in patients with diabetes insipidus who did not receive anti-diuretic hormone replacement. Twenty-seven patients suffered at least one cardiac arrest. The data on post-transplant function were obtained for 129 kidneys (from 70 donors) 30 livers and 9 hearts. Fifty-two kidneys, 10 livers and 2 hearts were transplanted from donors who had suffered at least one cardiac arrest without apparent adverse effect on post-transplant organ function. Thirty-six kidneys from 31 donors suffered either acute tubular necrosis (ATN) or primary non-function. The donors of these organs spent longer in ICU (60.6 +/- 45.7 h versus 41.8 +/- 30.1 h p = 0.045) and had a higher mean maximum serum sodium concentration (163.4 +/- 10.9 versus 158.5 +/- 9.5 mmol/l p = 0.05) than those without these complications. The serum creatinine concentration and degree of inotropic support did not predict post-transplant function. Standard biochemical tests for hepatic function, the dose of inotropic agent received, time in ICU and incidence of hypotension did not predict post-transplant liver function. CONCLUSIONS: Aggressive fluid resuscitation and management of diabetes insipidus may promote stability in paediatric organ donors. Donor cardiac arrest does not alter the ICU course or compromise post-transplant organ function. The current criteria used for donor selection failed to predict post-transplant organ function and their use may increase organ wastage.

Partial recovery of neutrophil functions during prolonged hypothermia in pigs.

The changes in circulation and migration of mature and immature neutrophils during 12 h of hypothermia have been studied using an experimental pig model. At 29 degrees C the number of circulating neutrophils fell from 5 +/- 1.1 at 37 degrees C to 3.5 +/- 0.6 X 10(9)/l and then remained unchanged while hypothermia was maintained. The number of circulating immature neutrophils did not fall during hypothermia. During hypothermia, hydrocortisone failed to stimulate the release of mature and immature neutrophils from the bone marrow. In contrast, endotoxin caused a profound neutropenia followed by a gradual increase in the number of circulating mature neutrophils, which by 6 h, was similar to the number circulating before endotoxin administration. At 29 degrees C the number of circulating immature neutrophils also fell following endotoxin but then increased over the number circulating before endotoxin administration by approximately 10-fold. Compared with neutrophil migration at 37 degrees C, very few mature or immature neutrophils migrated to an inflammatory site during the 12 h of hypothermia (29 degrees C). Unlike hypothermia in vitro, where neutrophil function may improve with time in vivo, neutrophil function remains compromised.

How to select optimal maintenance intravenous fluid therapy.

Hyponatraemia is the commonest electrolyte abnormality in hospitalized patients. If the plasma sodium concentration (P(Na)) declines to approximately 120 mM in <48 h, brain cell swelling might result in herniation, with devastating consequences. The volume and/or the composition of fluids used for intravenous therapy often contribute to the development of acute hyponatraemia. Our hypothesis is that the traditional calculation of the daily loss of insensible water overestimates this parameter, leading to an excessive daily recommended requirement for water. We offer suggestions to minimize the risk of iatrogenic hyponatraemia.

Determinants of success in pediatric cardiac patients undergoing extracorporeal membrane oxygenation.

BACKGROUND: The purpose of this retrospective study is to determine the possible predictors of successful cardiac recovery using extracorporeal membrane oxygenation (ECMO) and the practical limits of ECMO support. METHODS: Information was gathered on 31 consecutive children with myocardial failure who could not be resuscitated with other means and underwent ECMO at the Hospital for Sick Children before January 1994. RESULTS: Of the children who underwent ECMO as a means of cardiac rescue, 14/31 (45%) were weaned successfully. Two distinct groups of children were evident based on their initial indications for ECMO: those who had postcardiotomy myocardial dysfunction (n = 25) and those with cardiomyopathy or myocarditis (n = 6). Children with residual defects after cardiotomy (n = 10) did not survive ECMO. Four of the 6 children with cardiomyopathy or myocarditis were weaned successfully. In either group of patients ECMO support beyond 6 days failed to resuscitate the myocardium; all attempts to violate this "time barrier" in our study inevitably failed. CONCLUSIONS: Postcardiotomy residual defects are a contraindication to ECMO. If children with residual defects are excluded, successful weaning from ECMO can be achieved in almost 70%, with almost all recovery occurring with the first 6 days of ECMO.

Successful use of intraaortic balloon pumping in a 2-kilogram infant.

Severe low cardiac output of unknown cause that did not respond to inotropic and ventilatory support developed in a 2-kg infant. Intraaortic balloon pumping was used successfully to acutely improve her cardiac function and peripheral perfusion and to decrease the requirement for inotropic medications. We describe the technique for insertion and the equipment used, as well as our experience with intraaortic balloon pumping in children.

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.