Teaching successful central venous cannulation in infants and children: audio Doppler versus anatomic landmarks.

OBJECTIVE: To determine if vein localization with an audio Doppler increases successful central venous cannulation and decreases complications in infants and children when performed by inexperienced operators, compared with vein localization by anatomic landmarks (ALs). DESIGN: A prospective cohort of infants and children undergoing central venous cannulation for cardiac surgery. SETTING: A university-affiliated children's hospital with a pediatric anesthesia fellowship program. PARTICIPANTS: All infants and children undergoing cardiac surgery between July 1, 1996, and January 1, 1997. INTERVENTIONS: Subjects had central venous catheters (CVCs) placed by an anesthesia fellow by either ALs or audio-Doppler localization of the veins. MEASUREMENTS AND MAIN RESULTS: Eighty-four children were studied. Internal jugular vein (IJV) cannulation was attempted in 71 (85%) children and femoral vein cannulation in 13 (15%) children. Time to catheter insertion, number of needle passes, and artery puncture were noted. Sixty-one of 63 (97%) children had successful central venous cannulation by an anesthesia fellow using audio-Doppler vein localization. This was significantly greater than the 13 of 21 (62%) successful cannulations among children who had veins localized by ALs. Time to insertion did not differ by method of vein localization; however, the number of needle passes was significantly greater in the AL group. Artery puncture did not differ significantly by method of vein localization. CONCLUSION: Vein localization by audio Doppler significantly increases the rate of successful central venous cannulation and decreases the number of needle passes in pediatric patients when used by inexperienced operators.

Use of pulse oximetry for blood pressure measurement after cardiac surgery.

Blood pressure measurement using pulse oximeter waveform change was compared with an oscillometric measurement and the gold standard, intra-arterial measurement, in children after cardiac surgery. Forty six patients were enrolled and divided into groups according to weight. Simultaneous blood pressure measurements were obtained from the arterial catheter, the oscillometric device, and the pulse oximeter. Pulse oximeter measurements were obtained with a blood pressure cuff proximal to the oximeter probe. The blood pressure measurements from the pulse oximeter method correlated better with intra-arterial measurements than those from the oscillometric device (0.77-0.96 v 0.42-0.83). The absolute differences between the pulse oximeter and intra-arterial measurements were significantly smaller than between the oscillometric and intra-arterial measurements in children less than 15.0 kg. The pulse oximeter waveform change is an accurate and reliable way to measure blood pressure in children non-invasively, and is superior to the oscillometric method for small patients.

Multi-institutional survey of graduates of pediatric anesthesia fellowship: assessment of training and current professional activities.

UNLABELLED: We surveyed all the graduates of four fellowship programs in pediatric anesthesia between 1985 and 1993 to assess their current professional activities, their evaluation of fellowship training, and their opinions on future directions of such training. One-hundred ninety-one (62%) of the graduates responded. Nearly all of the respondents had sought fellowship training for pediatric anesthesia and thought that the training was worthwhile. At the time of the survey, 40% worked in a children's hospital, 72% had university or affiliate positions, and 54% had a practice that was > 50% pediatric. Those with > or = 12 mo fellowship and/or board certification in pediatrics were the most likely to have a pediatric-dedicated practice. Seventy percent of the respondents thought that fellowship training should be for 12 mo, and the proportion of respondents who recommended inclusion of training in pain management and clinical research was greater than the number who had actually received such training. Fifty-eight percent of respondents supported restriction of fellowship positions in the future, but 83% did not support a mandatory 2-yr fellowship with research training. We conclude that fellowships in pediatric anesthesia seem to be successful in providing training that is not only satisfying to the trainees, but that is also followed by active involvement in the care of children and in the training of residents and fellows in anesthesia. Additional information should be gathered to assess the impact of this training on pediatric care, to formulate a standardized curriculum, and to justify support for such training in the future. IMPLICATIONS: We surveyed graduates of four fellowship programs in pediatric anesthesia (1985-1993) to assess current professional activities, fellowship training, and future directions of such training. Fellowships in pediatric anesthesia seem to provide training that is satisfying to trainees and that is followed by active involvement in the care of children.

Hemodynamic effects of amrinone in children after Fontan surgery.

After Fontan repair in children, we performed a prospective, open-label study to evaluate the effect of amrinone on pulmonary vascular resistance (PVRI). Eight patients who underwent the Fontan repair had baseline arterial pressure, left atrial pressure, central venous pressure, and cardiac output measured postoperatively. Hemodynamic measurements were repeated after amrinone 4.5 mg/kg. The PVRI tended to decrease, but the change was not statistically significant. Although the systemic vascular resistance decreased to 802 +/- 222 from 941 +/- 191 dynes.s.cm-5.m-2 (P < 0.05), mean arterial blood pressure was unchanged. Cardiac index (3.8 +/- 1.2 to 4.7 +/- 1.6 L.min-1.m-2) and stroke volume index (23.6 +/- 6.7 to 30.5 +/- 8.1 mL.beat-1.m-2) increased, and heart rate decreased (160 +/- 21 to 151 +/- 24 bpm) (P < 0.05). Colloid transfusion during amrinone bolus administration was 13.9 mL/kg. The mean serum amrinone concentration was 4.2 micrograms/mL at the end of bolus and clearance was 2.24 mL.kg-1.min-1. Arrhythmias and thrombocytopenia were not noted. We conclude that amrinone administration is effective in increasing cardiac output in children who have undergone a Fontan repair.

Amrinone loading during cardiopulmonary bypass in neonates, infants, and children.

OBJECTIVES: To determine whether amrinone is bound to cardiopulmonary bypass circuits. When amrinone is administered to children during cardiopulmonary bypass, determine whether measured amrinone concentrations differ from those predicted based on a reported volume of distribution of 1.6 L/kg. DESIGN: In vitro study: Uptake of amrinone by cardiopulmonary bypass circuits was determined. Clinical study: Prospective, open label investigation. SETTING: University-affiliated tertiary children's hospital. PARTICIPANTS: Clinical study: 27 children participated, including 5 neonates and 9 infants. INTERVENTIONS: In vitro study: Waste blood was circulated within seven pediatric cardiopulmonary circuits. Amrinone was administered, and blood was serially assayed for amrinone levels. Clinical study: Amrinone (mean dose 4.9 mg/kg) was loaded during cardiopulmonary bypass and amrinone concentrations in pump blood were determined at termination of bypass. Amrinone measured by high-performance liquid chromatography. MEASUREMENTS AND MAIN RESULTS: Cardiopulmonary bypass circuit uptake reduced amrinone concentrations to 79% of predicted. After correcting for circuit uptake, serum amrinone levels in patients were significantly higher than predicted. The levels, expressed in the ratio of measured: predicted amrinone concentration, did not differ among neonates, infants, and children older than 1 year of age. CONCLUSIONS: When amrinone is administered to children during cardiopulmonary bypass, about 20% of the dose becomes bound to the circuit. Available drug is distributed within a smaller volume than predicted. This may be the consequence of the physiologic perturbations of hypothermic cardiopulmonary bypass.

Intraoperative transesophageal echocardiography of coronary artery fistulas.

Coronary artery fistula is a rare abnormality but one with substantial surgical importance, as operation abolishes the fistulous shunt volume, progressive coronary dilatation, and potential coronary steal. Prior reports emphasize the utility of direct inspection on cardiopulmonary bypass, with visualization of drainage of blood or cardioplegia from the fistulous connection, to define the drainage site. We report 3 patients in whom intraoperative transesophageal echocardiography was used for precise localization of the fistulous drainage site, selective demonstration of vessels feeding the fistulas, and documentation of abolition of fistulous flow, all without need for cardiopulmonary bypass. In addition, the technique provides for continuous monitoring of ventricular function, providing the opportunity to detect inadvertent ischemic effects of ligation. This approach appears to have considerable utility.

Hemodynamic effects of amrinone and colloid administration in children following cardiac surgery.

Amrinone was used as the sole vasoactive medication in 9 of 14 children (aged 5 months to 8.25 years) given the drug following open repair of congenital cardiac lesions. Four children received a concomitant dopamine infusion and one infant had the infusion stopped after 5 hours for low mean arterial pressure (49 mmHg). In the 10 children receiving only amrinone, cardiac index increased 21% (range, 0 to 94%) after a total loading dose of 4.5 mg/kg given over 1 hour. Four of 14 patients (29%) required dopamine infusions to maintain mean arterial pressure over 55 mmHg and in these children cardiac index increased from baseline and was maintained during the amrinone infusion. Preload was held constant by administration of whole blood or plasmanate during amrinone loading; a decrease in systemic vascular resistance index was seen resulting in a stable arterial blood pressure. Minimal chronotropic effect was seen and no arrhythmias occurred. The sole child with postoperative pulmonary hypertension had a beneficial decrease in pulmonary artery pressure, increase in cardiac index, and stable systemic blood pressure during amrinone use. Cardiac index changes during amrinone loading in these children were variable and less clearly related to serum levels than reported in adults. Pharmacokinetic analysis in 12 children showed a clearance of 3.4 mL/min/kg, a volume of distribution of 1.65 L/kg, and an elimination half-life of 5.75 hours. Decreases in platelet counts were seen in 6 children and platelet transfusion was needed in 1; thus, serial platelet counts should be monitored.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular outflow tract obstruction: an indication for intraoperative transesophageal echocardiography.

Transesophageal echocardiography (TEE) provides detailed anatomic imaging of both discrete and complex forms of left ventricular outflow tract (LVOT) obstruction, and Doppler techniques provide additional information regarding the site, mechanism, and severity of the obstruction. Because the transaortic surgical approach to LVOT obstruction often provides limited direct visualization during surgery, we sought to evaluate the utility of intraoperative TEE during surgery for LVOT obstruction. We tested the hypotheses that intraoperative TEE would (1) be useful in defining the level and nature of LVOT obstruction, (2) serve to direct the surgical approach, (3) define the adequacy of relief of LVOT obstruction, and (4) detect surgical complications. Study population consisted of a consecutive series of 27 infants and children undergoing surgery for LVOT obstruction. Patient age ranged from 0.5 to 17.9 years, and weight from 5.4 to 71.2 kg. In 14 patients LVOT obstruction resulted from a discrete membrane, whereas 13 had complex forms of LVOT obstruction. Fully anesthetized and monitored patients were examined with 5 MHz TEE probes appropriate to the size of the patient. In the 14 patients with discrete LVOT obstruction, discrete membranes were identified by TEE in all; gradients ranged from 36 to 75 mm Hg. In 13 of 14 patients, postbypass TEE demonstrated removal of the membrane and excellent relief of gradients. In one of these patients, TEE demonstrated a small ventricular septal defect acquired during resection; the patient was returned to bypass for closure. In one patient, return to bypass for further resection of LVOT obstruction was prompted by TEE demonstration of a high residual gradient. In the 13 patients with complex LVOT obstruction, TEE demonstrated the complexity of LVOT obstruction in all. Gradients ranged from 4 to 95 mm Hg. Although this information was used in surgical planning, five patients had high residual gradients after bypass and underwent further resection. An additional two were returned to bypass for mitral valve replacement. Overall, 8 of 27 patients (29.6%) were returned to bypass based on TEE demonstration of residual anatomic or hemodynamic abnormalities. This occurred significantly more frequently in complex LVOT obstruction than in discrete LVOT obstruction (p = 0.045). We conclude that intraoperative TEE has substantial utility in the demonstration of site, mechanism, and severity of LVOT obstruction and for surgery designed to relieve LVOT obstruction. We believe that TEE should be an integral part of surgical management of LVOT obstruction.

Transesophageal echocardiography during repair of congenital cardiac defects: identification of residual problems necessitating reoperation.

One advantage of intraoperative transesophageal echocardiographic (TEE) evaluation during surgery for congenital heart disease is detection of suboptimal repairs, thus providing the opportunity to return to cardiopulmonary bypass (CPB) to repair residual defects. The purpose of this study was to evaluate the impact of TEE on decisions to return to CPB. Two-hundred-thirty infants and children with a variety of defects were studied with size-appropriate TEE probes. Patients were grouped by anatomic defect or surgical procedure for which TEE was requested. After CPB, pre- and post-CPB TEE anatomic, functional, and flow evaluations were compared. TEE findings prompted a return to CPB to repair residual defects in 17 of 230 (7.4%) patients. By diagnosis, return to CPB occurred in 9 of 28 (32%) patients with left ventricular outflow tract obstruction, 5 of 78 (6.4%) patients with ventricular septal defect, 1 of 16 (6%) patients with switch-repaired transposition, 1 of 32 (3%) with aortic valve disease, and 1 of 3 with double outlet right ventricle. All post-CPB diagnoses were confirmed during reoperation. Although post-CPB TEE provided reassuring information in patients with other diagnoses, TEE impact on return to CPB appears to be significant in a small group of primary diagnoses. The sensitivity and specificity of TEE determination of the need for reoperation were 89% and 100%, respectively. By identifying the site, severity, and mechanism of residual problems, TEE offers substantial utility in detection of residual problems in need of reoperation.

Effects of the thromboxane synthetase inhibitor, dazmegrel (UK 38,485), on pulmonary gas exchange and hemodynamics in neonatal sepsis.

Group B streptococcal (GBS) sepsis produces arterial hypoxemia in newborns. In piglets we previously found that hypoxemia develops because of increased ventilation perfusion heterogeneity, and reduced mixed venous pO2 occurring in association with decreased pulmonary blood flow. We hypothesize that increased thromboxane A2 (TxA2) synthesis mediates the immediate alterations in gas exchange found in GBS sepsis. We studied 18 anesthetized, ventilated piglets before, during, and after a 30-min infusion of 2 X 10(9) colony forming units/kg of GBS. Nine piglets were pretreated with 8 mg/kg of dazmegrel (DAZ), a TxA2 synthetase inhibitor, and nine animals received GBS without DAZ pretreatment. Pulmonary and systemic arterial pressures, pulmonary vascular resistance, pulmonary blood flow, respiratory gas tensions, intrapulmonary shunt, and SD of pulmonary blood flow, an index of ventilation perfusion mismatching, were measured. Systemic and pulmonary arterial levels of thromboxane B2 and 6-keto-PGF1 alpha were also measured. The sham-treated animals showed the expected rise in pulmonary arterial pressure from 12 +/- 3 to 29 +/- 7 torr, (p less than 0.02). By comparison, the animals pretreated with DAZ did not demonstrate pulmonary arterial hypertension and had a delay in the fall in pulmonary blood flow until 2 h postinfusion. Arterial PO2 did not decline significantly after the GBS infusion in the DAZ-pretreated animals; the untreated animals showed a significant fall in pO2 from baseline. There was no significant change in intrapulmonary shunt or SD of pulmonary blood flow compared to baseline in the DAZ-pretreated animals. The elevation in thromboxane B2 occurring with GBS sepsis did not occur in the DAZ-pretreated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of pulmonary gas exchange abnormalities during experimental group B streptococcal infusion.

Group B streptococcal sepsis in newborns produces pulmonary arterial hypertension and hypoxemia. The purpose of this study was to investigate the mechanisms by which hypoxemia occurs. Ten anesthetized, ventilated piglets were infused with 2 X 10(9) colony forming units/kg of Group B streptococci over a 30-min period. Pulmonary arterial pressure rose from 14 +/- 2.8 to 38 +/- 6.7 torr after 20 min of the bacterial infusion (p less than 0.01). During the same period, cardiac output fell from 295 to 184 ml/kg/min (p less than 0.02). Arterial PO2 declined from 97 +/- 7 to 56 +/- 11 torr (p less than 0.02) and mixed venous PO2 fell from 39.6 +/- 5 to 28 +/- 8 torr (p less than 0.05). The multiple inert gas elimination technique was used to detect increases in shunt and alterations in ventilation-perfusion matching. Intrapulmonary shunt did not increase during or after the infusion with group B streptococci. However, there was a significant increase (p less than 0.05) in the SD of pulmonary blood flow, an index of VA/Q mismatching, 20 min after initiation of the infusion of bacteria. All the above changes reverted toward baseline during the 2-h period following discontinuation of the infusion. We conclude that the hypoxemia occurring in the early phase of group B streptococcal sepsis does not develop solely because of increased shunt, but rather is produced by a decline in cardiac output in conjunction with mismatching of pulmonary perfusion to alveolar ventilation.

Bronchopulmonary dysplasia and pulmonary insufficiency of prematurity. Lack of correlation of outcome with gas exchange abnormalities at 1 month of age.

A review of all infants admitted to the two intensive care nurseries in Seattle from July 1, 1980, through Dec 31, 1981, was performed to evaluate the outcome of infants still requiring supplemental oxygen and/or mechanical ventilation at 1 month of age. Sixty-three infants were identified. Fifty-six infants survived to at least 2 years of age, including 11 of 13 in the subgroup of infants requiring 40% or more oxygen at 1 month of age. Eight (14%) of the 56 survivors have required prolonged rehospitalization for pneumonia or other respiratory illnesses in the first two years following birth. We conclude that the degree of gas exchange impairment assessed at 1 month of age does not predict ultimate outcome from neonatal chronic lung disease.