Phrenic nerve paralysis after pediatric cardiac surgery. Retrospective study of 125 cases.

Phrenic nerve paralysis was diagnosed in 125 children (1.6%) from a series of 7,670 cardiac surgical procedures in infants and children during a 12 year period. The incidence was 1.9% for open heart and 1.3% for closed heart operations. In order of decreasing incidence, the open heart procedures included Mustard procedure (6.7%), right ventricular outflow tract reconstruction (5.6%), and repair of tetralogy of Fallot (2.7%). The closed heart procedures included Glenn anastomosis (6.2%), Blalock-Hanlon atrial septectomy (5.9%), and right Blalock-Taussig shunt (5.1%). Procedures following previous operations or thoracotomies had almost twice the incidence of phrenic nerve paralysis: Mustard procedure 9.9%, right ventricular outflow tract reconstruction 10.8%, and tetralogy repair 5.5%. Seven patients (5.6%) with phrenic nerve paralysis died. Patients less than 2 years old with phrenic nerve paralysis were intubated for 0 to 57 (average 15.7) days after their cardiac operations and those over 2 years old for 13 to 35 (average 7.2) days (p less than 0.001). Twelve patients had diaphragmatic plication without mortality and were extubated 0 to 6 (average 2.3) days after plication. We have made the following conclusions: (1) Phrenic nerve paralysis may occur after both open and closed cardiac procedures and is more common in children requiring reoperation; (2) it is associated with considerable morbidity; (3) eventual recovery of phrenic nerve function occurs in 84% of children; and (4) diaphragmatic plication is safe, reliable, and of most value in patients who are under 2 years of age and require mechanical ventilation for more than 2 weeks.

Intraaortic balloon pumping in children.

From June, 1977, to December, 1978, 14 children had intraaortic balloon support after open-heart operation. There were 6 long-term survivors. Four of 5 children more than 10 years old and 2 of 5 children between 5 and 10 years old survived. All 4 children less than 5 years old died. In the youngest group, it was difficult to use the balloon successfully because of their very low cardiac output coming off bypass and their greater aortic elasticity. The smallest sizes of balloon available were found to be too long, extending well below the diaphragm in younger patients. In 7 out of 10 patients 5 years old or more, augmentation was obtained.

The source of coronary perfusion during partial bypass for extracorporeal membrane oxygenation (ECMO).

The proper siting of cannulas to return oxygenated blood to patients on long-term membrane oxygenator support is as yet undecided. This experimental study on adult sheep shows the problems of obtaining perfusion of the coronary arterial tree when blood is returned to the ascending aorta. Our 11 experiments demonstrate that the coronary arterial tree is perfused with blood ejected from the left ventricle except during very high bypass flows (85% bypass) or when the aortic valve is rendered incompetent.

Plication of the diaphragm for infants and young children with phrenic nerve palsy.

Phrenic nerve palsy (PNP) is seen in infants and young children usually resulting from operative trauma or birth injury. Spontaneous recovery usually occurs, but occasionally surgical plication is necessary. Twenty-three cases of PNP over a 10-year period were managed surgically. Patient ages ranged from 1 day to 30 months (median, 4 months), 18 were male and five female. Cause was operative trauma in 18 (17 cardiac surgery, one neuroblastoma), birth trauma in two, and idiopathic in three. The right side was involved in 14, the left in eight, and both in one. Indications for plication were inability to wean from the ventilator (group 1, 16 patients), recurrent pneumonia (group 2, four patients), and respiratory distress (group 3, three patients). The 16 patients in group 1 were intubated for a median of 18.5 days from onset of PNP to plication. Postoperatively, three had continuing congestive heart failure (one died at 16 days of age, one was still chronically ventilated at 22 months, one was extubated at nine days); the other 13 were extubated at a median of two days postoperatively. All the patients in groups 2 and 3 were extubated within two days of surgery. Twelve plications were transthoracic and 11 were transabdominal. Postoperative complications included pneumonia (2), wound infection (1), pneumothorax (2), and mucous plug with pulmonary collapse (1). One patient died of cardiac failure at 16 days. One patient in group 3 developed recurrent respiratory distress 4 months postoperatively; he had a recurrent elevated hemidiaphragm requiring a second plication.(ABSTRACT TRUNCATED AT 250 WORDS)

Diaphragmatic paralysis after pediatric cardiac surgery: a retrospective analysis of 34 cases.

Thirty-four cases of diaphragmatic paralysis after pediatric cardiac surgery are reviewed. Differences between pediatric and adult pulmonary physiology account for the increased severity of respiratory distress seen in children with this condition. The efficacy of treatment with endotracheal intubation and continuous positive airway pressure (CPAP) is confirmed. No patient over 3 yr of age required intubation for longer than 2 wk. This finding is consistent with the development of sufficient chest wall stability to compensate for paralysis of the hemidiaphragm. Patients under 3 yr of age, without complicating heart failure, who still required intubation and CPAP 3-4 wk after injury to the phrenic nerve should consider operative plication.

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.

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.

Importance of mixed venous oxygen saturation in the care of critically ill patients.

The relation between mixed venous oxygen saturation and cardiac index was determined in 11 children who underwent surgical treatment for congenital heart disease. The correlation between these two variables was found to be reliable (r = 0.78, P = 0.001). The simple determination of mixed venous oxygen saturation performance, particularly when sophisticated equipment for measuring cardiac output is not available.

Pharmacokinetics of cimetidine in critically ill children.

The pharmacokinetic behavior of cimetidine has not been described in children, and there is no authoritative guideline on cimetidine dosage for children. Cimetidine pharmacokinetics were studied after a single intravenous dose and during three, incremental rates of continuous infusion in critically ill children. The mean elimination half-life of cimetidine was 1.44 +/- 0.41 hours. Compared to adults, these children had a relatively faster clearance (14.21 +/- 2.85 ml/min/kg) of cimetidine and a larger apparent distribution volume (2.13 +/- 0.63 l/kg). Based on our results, it appears rational to initiate cimetidine at a daily dose of 24 mg/kg in critically ill children.

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.

Early nosocomial infections in pediatric cardiovascular surgery patients.

All patients undergoing cardiovascular surgery between July 1, 1987 and February 29, 1988 were followed from admission to the pediatric ICU (PICU) daily by an intensivist/anesthetist. Patients were characterized by surgical procedure and PRISM score on ICU admission. Of 310 patients, 40 patients (nosocomially infected patient ratio 12.9) developed 78 infections (nosocomial infection ratio 25.2), of which 28% (n = 22) were wounds, within 2 months of surgery. Early wound infection followed 8% of closed, nonpump cases and 6.7% of open, pump cases. Wound infection was more likely if the sternum was open on the ward (elective or emergency) (27.6% open vs. 5.0% closed, p less than .001) or if the PRISM score was greater than or equal to 10 on PICU admission (10.7% greater than or equal to 10 vs. 2.3% less than 10, p less than .01). The causative agents in wound infections in closed cases were Staphylococcus aureus (70%) and coagulase negative staphylococci (CONS) (30%) while in open, pump cases the agents were CONS (33%), Pseudomonas aeruginosa (27%), Candida spp. (27%), and S. aureus (20%). Nonwound infections accounted for 72% of infections (n = 56). The number of bacteremias and other central and arterial line-related infections approximated wound infection in incidence at 6.8/100 patients. Wound infections are more likely if the sternum has been left open on the ward, if the patient has a high PRISM score on PICU admission, and after specific surgical procedures.