Acute hepatic failure following cardiac operation in children.

A retrospective analysis has been performed of children who have undergone cardiac operations during the past 6 years to determine the clinical presentation and management of acute hepatic failure (AHF) in the postoperative period. Eleven patients had a clinical picture of AHF with jaundice, elevation of the levels of serum glutamic oxaloacetic transaminase (SGOT) and serum ammonia, and marked prolongation of the prothrombin time associated with failure of hemostasis. Hypoglycemia developed in seven. All patients had evidence of low cardiac output and acute renal failure. Patients with AHF had evidence of reduced hepatic perfusion during the previous 24 hours with reduced mean arterial pressure and elevated central venous pressure. Six children died of myocardial failure. A modified Fontan procedure was performed in six children, of whom four died. All had a right atrial pressure of 21 torr or greater. Five children survived the acute episode of hepatic failure. The importance of early diagnosis and effective management of complications such as hypoglycemia and the bleeding tendency are emphasized.

Myocardial performance after repair of congenital cardiac defects in infants and children. Response to volume loading.

The hemodynamic response to increasing left atrial pressure by volume loading was evaluated in 70 children during the first 24 hours after repair of congenital cardiac defects. The children were grouped into four diagnostic categories: atrial septal defect or pulmonary valve stenosis (n = 8), ventricular septal defect (n = 36), complete transposition after Mustard's operation (n = 13), and tetralogy of Fallot (n = 13). Within 2 hours of bypass, both cardiac index and left ventricular stroke work index were adequate and increased appropriately with volume loading in all four diagnostic groups. The atrial septal defect group demonstrated a similar response to volume loading 4 and 24 hours after bypass. However, the other three diagnostic groups had a higher filling pressure, lower cardiac index and stroke work index, and a depressed response to increasing preload 4 hours postoperatively, which indicated a deterioration in cardiac performance. The deterioration was maximal between 4 and 12 hours after bypass, and performance tended to recover 24 hours postoperatively. The transposition group had a more profound depression in cardiac performance than the other two groups. Within the ventricular septal defect group, smaller children (body surface area less than 0.36 m2) had a more profound depression in performance than larger children. These results demonstrate a significant alteration in cardiac performance during the first 24 hours after repair of congenital cardiac defects in children. These changes should be considered when postoperative management is being planned.

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.

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.

Effect of propionyl-L-carnitine on exercise performance in peripheral arterial disease.

BACKGROUND: Supplementation with propionyl-L-carnitine (PLC) may be of use in improving the exercise capacity of people with peripheral arterial disease. METHODS: After a 2-wk exercise familiarization phase, seven subjects displaying intermittent claudication were studied over a 12-wk period consisting of three 4-wk phases, baseline (B), supplementation (S), and placebo (P). PLC was supplemented at 2 g x d(-1), and subjects were blinded to the order of supplementation. Unilateral calf strength and endurance were assessed weekly. Walking performance was assessed at the end of each phase using an incremental protocol, during which respiratory gases were collected. RESULTS: Although there was not a significant increase in maximal walking time ( approximately 14%) in the whole group, walking time improved to a greater extent than the individual baseline coefficient of variation in four of the seven subjects. The changes in walking performance were correlated with changes in the respiratory exchange ratio both at steady state (r = 0.59) and maximal exercise (r = 0.79). Muscle strength increased significantly from 695 +/- 198 N to 812 +/- 249 N by the end of S. Changes in calf strength from B to S were modestly related to changes in walking performance (r = 0.56). No improvements in calf endurance were detected throughout the study. CONCLUSIONS: These preliminary data suggest that, in addition to walking performance, muscle strength can be increased in PAD patients after 4 wk of supplementation with propionyl-L-carnitine.

Purulent otitis media--a "silent" source of sepsis in the pediatric intensive care unit.

Septicemia is common in patients in the pediatric intensive care unit (ICU) who have nasotracheal tubes. Although it is frequently caused by middle ear effusion (MEE), pneumatic otoscopy is not routinely performed in these patients. To demonstrate the value of this procedure, 46 pediatric ICU patients with nasotracheal tubes were followed daily with pneumatic otoscopy for 11 to 98 days and compared with 25 controls without nasotracheal tubes, 12 of whom had nasogastric tubes. Myringotomy was performed whenever blood culture became positive. MEE was significantly more frequent in patients with nasotracheal tubes (87%) than in patients with controls (23%) and occurred first on the side of intubation. Blood bacteria were identical to middle ear pathogens in 80% of patients. Nasogastric tubes were not significant in causing MEE. The high incidence of MEE resulting from nasotracheal intubation indicates the importance of including pneumatic otoscopy in the daily examination of these high-risk patients.

Tracheoplasty--a new operation for complete congenital tracheal stenosis.

This is a report of a case of complete congenital tracheal stenosis confirmed by tracheobronchogram. The stenosis also involved the origin of the right main bronchus. The membranous portion of the trachea was absent. It was repaired through a sternotomy and right thoracotomy aided by partial cardiopulmonary bypass. The posterior trachea was opened from larynx to carina and on into the right main bronchus, and each posterior tracheal edge was sewn to the anterior wall of the esophagus with a running Prolene suture. Three months after repair bronchoscopy showed that the new membranous trachea was epithelialized and the entire airway was of good caliber; the only problem was a diffuse tracheomalacia. He died in his seventh postoperative month after a major airway complication due to tracheotomy, which occurred after an elective bronchoscopy. It is obvious that this operation is technically feasible. It was hoped that his airway would become sufficiently stable to allow the tracheotomy tube to be removed at some time in the future.

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.

Effects of ionic strength on lysozyme uptake rates in cation exchangers. I: Uptake in SP Sepharose FF.

Fluorescence scanning confocal microscopy was used in parallel with batch uptake and breakthrough measurements of transport rates to study the effect of ionic strength on the uptake of lysozyme into SP Sepharose FF. In all cases the adsorption isotherms were near-rectangular. As described previously, the intraparticle profiles changed from slow-moving self-sharpening fronts at low salt concentration, to fast-moving diffuse profiles at high salt concentration, and batch uptake rates correspondingly increased with increasing salt concentration. Shrinking core and homogeneous diffusion frameworks were used successfully to obtain effective diffusivities for the low salt and high salt conditions, respectively. The prediction of column breakthrough was generally good using these frameworks, except for low-salt uptake results. In those cases, the compressibility of the stationary phase coupled with the shrinking core behavior appears to reduce the mass transfer rates at particle-particle contacts, leading to shallower breakthrough curves. In contrast, the fast uptake rates at high ionic strength appear to reduce the importance of mass transfer limitations at the particle contacts, but the confocal results do show a flow rate dependence on the uptake profiles, suggesting that external mass transfer becomes more limiting at high ionic strength. These results show that the complexity of behavior observable at the microscopic scale is directly manifested at the column scale and provides a phenomenological basis to interpret and predict column breakthrough. In addition, the results provide heuristics for the optimization of chromatographic conditions.

Hemodynamic effects of dobutamine after cardiopulmonary bypass in children.

The synthetic inotropic agent, dobutamine, has reportedly increased cardiac output in adults after cardiopulmonary bypass with minimal side effects. Its use in children, after surgical correction of congenital heart disease, was tested by infusing the drug at 1, 4, 7, and 10 micrograms/kg x min in 11 children. While significant increases in cardiac index above control (23, 23, and 16% at 4, 7, and 10 micrograms/kg x min, respectively) were observed, this was achieved at the expense of significant increases in heart rate (15, 24, and 10%). This increase in heart rate (47% in one child) necessitated discontinuing the infusion in 4 subjects. There were also significant increases in systolic and mean blood pressure with no change in stroke volume or peripheral vascular resistance. The authors conclude that in children, dobutamine is an effective inotropic agent acting principally by stimulating beta 1-receptors in the myocardium producing a predominantly chronotropic effect without significant changes in peripheral vascular resistance. Given the intrinsically higher heart rate of children, the levels of tachycardia produced by the drug in some instances reach unacceptable levels and as such, may make dopabutamine unsuitable for use in children after cardiopulmonary bypass.

Evaluation of pulmonary function in muscular dystrophy patients requiring spinal surgery.

Scoliosis associated with muscular dystrophy frequently necessitates surgical stabilization of the spine. The timing of surgery usually is based on the degree of spinal angulation. Pulmonary function, which deteriorates with age in children with muscular dystrophy, should also be an important consideration in this timing. In a retrospective study of 48 patients who underwent spinal stabilization, preoperative respiratory function tests were correlated with postoperative respiratory complications. The percentage of predicted vital capacity provided the best indicator of outcome and values of less than 30% were associated with major respiratory complications. Spinal fixation failed to arrest the decline in respiratory function in these patients, but it seemed to slow the rate of deterioration compared with preoperative changes. Evaluation of pulmonary function should play a major role in the timing of surgical intervention in muscular dystrophy.

Neutral amino acid transport in bovine articular chondrocytes.

1. The sodium-dependent amino acid transport systems responsible for proline, glycine and glutamine transport, together with the sodium-independent systems for leucine and tryptophan, have been investigated in isolated bovine chondrocytes by inhibition studies and ion replacement. Each system was characterized kinetically. 2. Transport via system A was identified using the system-specific analogue alpha-methylaminoisobutyric acid (MeAIB) as an inhibitor of proline, glycine and glutamine transport. 3. Uptake of proline, glycine and glutamine via system ASC was identified by inhibition with alanine or serine. 4. System Gly was identified by the inhibition of glycine transport with excess sarcosine (a substrate for system Gly) whilst systems A and ASC were inhibited. This system, having a very limited substrate specificity and tissue distribution, was also shown to be Na+ and Cl- dependent. Evidence for expression of the system Gly component GLYT-1 was obtained using the reverse transcriptase-polymerase chain reaction (RT-PCR). 5. System N, also of narrow substrate specificity and tissue distribution, was shown to be present in chondrocytes. Na+-dependent glutamine uptake was inhibited by high concentrations of histidine (a substrate of system N) in the presence of excess MeAIB and serine. 6. System L was identified using the system specific analogue 2-aminobicyclo(2,2, 1)heptane-2-carboxylic acid (BCH) and D-leucine as inhibitors of leucine and tryptophan transport. 7. The presence of system T was tested by using leucine, tryptophan and tyrosine inhibition. It was concluded that this system was absent in the chondrocyte. 8. Kinetic analysis showed the Na+-independent chondrocyte L system to have apparent affinities for leucine and tryptophan of 125 +/- 27 and 36 +/- 11 microM, respectively. 9. Transport of the essential amino acids leucine and tryptophan into bovine chondrocytes occurs only by the Na+-independent system L, but with a higher affinity than the conventional L system.

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.

Postoperative hypertension after repair of coarctation of aorta in children: protective effect of propranolol?

The effects of the nonselective beta blocker, propranolol, on coarctectomy-induced hypertension were evaluated relative to changes in cardiac function, sympathetic tone, and plasma renin activity (PRA). A randomized, placebo-controlled, double-blind, age-stratified design was employed. Propranolol (n = 11, mean age 9.4 years) or placebo (n = 12, mean age 10.2 years) was started 2 days before surgery and continued until 6 days after surgery. In patients on placebo, systolic and diastolic blood pressure, heart rate, and cardiac index increased rapidly and peaked within 1 day after surgery. Over the ensuing days these increases gradually abated. Plasma epinephrine and PRA increased markedly within 12 hours after surgery, but returned quickly toward preoperative levels. In contrast, plasma norepinephrine increased more gradually and remained elevated longer. In patients on propranolol, systolic blood pressure, heart rate, cardiac index and PRA showed only negligible increases. However, diastolic blood pressure, increased even faster with propranolol than with placebo but to the same extent. Plasma catecholamines showed similar increases on the two treatments. Only in the placebo group was the code broken in the intensive care unit because of hypertension uncontrolled by sodium nitroprusside; this occurred in 6 of 12 patients. We conclude that nonselective beta blockade ameliorates the hyperdynamic circulation and increase in systolic blood pressure following coarctectomy. The initial increase in diastolic blood pressure following surgery in the propranolol group may have been caused by vascular beta-2-receptor blockade resulting in unopposed alpha-receptor-mediated vasoconstriction.

Effect of surgical repair on respiratory mechanics in congenital diaphragmatic hernia.

To determine whether surgical repair of congenital diaphragmatic hernia (CHD) results in improvement in respiratory mechanics, we measured respiratory system compliance in nine patients (five survivors and four nonsurvivors) before and after operation. In all nine infants, CHD was diagnosed within 6 hours of life, and surgical repair was through an abdominal approach after a period of stabilization. Measurements were made noninvasively, using the passive expiratory flow-volume technique. In only one of the nine infants did compliance immediately improve after surgical repair, and in another it showed no change. Both of these infants survived, with an uneventful postoperative course. In the remaining seven infants, however, postoperative compliance immediately decreased to 10% to 77% from the preoperative value. The four infants with more than 50% decrease in compliance died with increasing hypoxemia and acidosis. These results suggest that respiratory mechanics in CHD, far from improving, frequently deteriorate as a result of repair of the hernia. The role of urgent surgery in this malformation should be reevaluated.

Influence of hypothermia, barbiturate therapy, and intracranial pressure monitoring on morbidity and mortality after near-drowning.

We retrospectively evaluated the clinical and pathologic effects of hypothermia and high-dose barbiturate therapy on hypoxic/ischemic cerebral injury after near-drowning in children. Of 40 near-drowned patients admitted to the ICU, 13 died, seven had permanent cerebral damage, and 20 survived. Twenty-four patients (group 1) were treated with a regime of hyperventilation, hypothermia, and high-dose phenobarbitone while intracranial pressure (ICP) was continuously monitored. Of ten who died in this group, three were diagnosed as having cerebral death shortly after admission; autopsy revealed severe cerebral edema with herniation. The remaining seven nonsurvivors had severe cerebral hypoxia without raised ICP and had the features of severe adult respiratory distress syndrome and hypoxic/ischemic damage to other organs. Six of these seven patients developed septicemia which was invariably associated with a profound neutropenia. Sixteen patients (group 2) were treated with a similar protocol but without hypothermia. Three of these patients died but only one developed septicemia. Neutropenia after resuscitation from near-drowning seemed to indicate a poor prognosis; the mean polymorphonuclear leukocyte count in nonsurvivors (1.9 +/- 0.5 X 10(9) cell/L) was significantly (p less than .01) lower than that in survivors (6.4 +/- 1.1 X 10(9) cell/L). Hypothermia was associated with a decreased number of circulating PMNs but did not increase the number of neurologically intact survivors. Similarly, although barbiturates may control ICP, their use did not improve outcome. Because severe cerebral edema and herniation after near-drowning is usually associated with irreversible brain damage, measures to control brain swelling such as hypothermia and barbiturates will be of little benefit.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombolytic therapy for femoral artery thrombosis after pediatric cardiac catheterization.

Femoral artery thrombosis remains a well-known complication after cardiac catheterization. A study was undertaken to assess the efficacy of thrombolytic therapy for this complication. A total of 526 consecutive infants and children were prospectively evaluated after cardiac catheterization, and the medical charts of 42 patients who required femoral artery thrombectomy between 1975 and 1985 were reviewed. In the prospective study, patients were given a bolus injection of heparin, 150 U/kg, at the time the artery was entered. Patients with persistently absent or diminished pulse 2 hours after catheterization received a second bolus injection of 50 U/kg followed by an infusion of 20 U/kg/hr heparin for a maximum of 48 hours. If the affected leg pulse was absent or reduced and the systolic Doppler blood pressure was less than two thirds that of the unaffected leg, thrombolytic therapy was begun. In the 42 patients with surgical thrombectomy, there were no serious complications of surgery. Forty-five of the 526 patients (8.6%) had a decreased or absent pulse after catheterization. Of these 45 patients, 32 (71.1%) improved with systemic heparinization only. Thirteen patients (28.9%) had a persistently absent pedal pulse suggesting femoral artery thrombosis, despite continuous heparinization. Eleven patients were successfully treated with thrombolytic therapy and two required surgical thrombectomy. Intraarterial balloon dilatation procedures were performed in 8 of these 13 patients. Prothrombin time was prolonged (11.5 +/- 1.06 to 52.3 +/- 40.4 seconds; p less than 0.025) and fibrinogen levels were significantly reduced (2.25 +/- 0.79 to 1.52 +/- 0.52 gm/dl; p less than 0.01) during therapy. There were no serious complications, although four patients bled from the groin entry site.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiographic tracheal diameter measurements in acute infectious croup: an objective scoring system.

The percentage of change in tracheal diameter (TD% change), as assessed by an objective radiological measurement, was used along with a simple subjective clinical score to assess response to therapy in upper airway obstruction in 14 patients with acute infectious croup. Studies were performed on the 14 patients, each of whom was randomly assigned to one of two treatment groups: distilled water or racemic epinephrine (RE), both being nebulized and delivered by manual IPPB. The objective radiological assessment and the subjective clinical score both confirmed that RE is significantly (p less than 0.005) more effective than distilled water in the acute relief of upper airway obstruction. The more precise radiological assessment may be of value in determining objectively better drug therapy for infectious croup.