Glucose versus lactated Ringer's solution during pediatric cardiac surgery

OBJECTIVE

Whether intraoperative fluid infusion should contain glucose during pediatric cardiac surgery remains controversial. This study was performed to compare the effects of glucose and glucose-free solutions on blood glucose and blood insulin levels during total repair of congenital heart diseases.

DESIGN

Prospective randomized and blinded study.

SETTING

Cardiovascular university center.

PARTICIPANTS

Forty nondiabetic children, weight ranging from 4 to 10 kg, scheduled for cardiac surgical procedures requiring cardiopulmonary bypass (CPB) without total circulatory arrest.

INTERVENTIONS

Group R (n = 20) was administered lactated Ringer's solution intraoperatively, and group G (n = 20) received 5% glucose. Fluids were infused at a rate of 3 mL/kg/h in the two groups from the induction of anesthesia to the end of the surgical procedure. Blood glucose and insulin were sampled before infusion (Tzero), before CPB (T1), 10 minutes after initiation of CPB (T2), 10 minutes after initiation of rewarming (T2), and at the end of the procedures (T4). Postoperatively, blood glucose was measured at the first, 12th, and 24th hours.

MEASUREMENTS AND RESULTS

During the prabypass period, three children in group R had severe hypoglycemia (blood glucose < 40 mg/dL). After initiation of CPB, blood glucose increased in both groups, with a small difference at the end of the procedure. No infants in the two groups had blood glucose higher than 239 mg/dL.

CONCLUSIONS

Glucose withdrawal during pediatric cardiac surgery induces threatening hypoglycemia during the prabypass period, and moderate intraoperative glucose administration (2.5 mg/kg/min) is not responsible for major hyperglycemia.

Pulsatility improves hemodynamics during fetal bypass. Experimental comparative study of pulsatile versus steady flow

BACKGROUND

The main advantage of pulsatile flow compared with steady flow during cardiopulmonary bypass is to prevent a rise in systemic vascular resistances. We hypothesized that pulsatile flow could overcome the progressive rise in peripheral and placental vascular resistances observed during fetal bypass and leading to progressive irreversible hypoxemia.

METHODS AND RESULTS

A study was undertaken in 17 fetal lambs (110 to 140 days of gestation). Fetal bypass was established for a 30-minute period through right atrial and main pulmonary artery cannulation. The circuit had no oxygenator. Flow was delivered by a standard roller pump for the continuous study (group 1, n = 9) or by a centrifugal pulsatile pump for the pulsatile study (group 2, n = 8). Oxymetric and hemodynamic parameters, along with organ blood flow determined by radiolabeled microspheres counting, were recorded before (T1) and after 10 minutes (T2) and 30 minutes (T3) of bypass. SaO2 and PaO2 were significantly higher in group 2 than in group 1 at T2 but thereafter deteriorated similarly in both groups, whereas PCO2 remained unchanged. Pump flow in group 2 was significantly higher than in group 1 at T2 and T3 (957.6 +/- 49 and 1104 +/- 152 versus 437.6 +/- 23 and 467.8 +/- 43 mL/min, respectively). Systemic vascular resistances during pulsatile bypass were also significantly lower than in group 1 at T2 (402 +/- 12 versus 930 +/- 79 dynes/sec/cm-5) and T3 (374 +/- 60 versus 1017 +/- 192 dynes/sec/cm-5). At T2 and T3, all individual blood flows except the brain but including the placenta were statistically higher in group 2 than in group 1. Placental vascular resistances gradually increased during bypass in group 1 to reach 2.9 +/- 0.2 mm Hg.mL-1.min-1.kg-1 at T3 and remained approximately stable in group 2 during 30 minutes of pulsatile bypass, varying from 0.35 +/- 0.02 to 1.26 +/- 0.14 from T2 to T3 (P < .01).

CONCLUSIONS

The data suggest that pulsatile flow for 30 minutes of bypass in a fetal lamb preparation temporarily prevents the progressive hypoxemia observed under steady-flow bypass. Pulsatile flow allows higher pump flow through a significant decrease in systemic vascular resistances. Individual organ blood flow, including placenta, was significantly higher under pulsatile bypass. With technical improvements in the design of pulsatile devices adapted to more physiological beat rates, pulsatility may become a valuable adjunct to overcome placental dysfunction observed during experimental fetal cardiac surgery.

[Surgical treatment of coarctation of the aorta in the infant less than a year old]

Between 1972 and 1984, 141 infants of less than 12 months of age were operated upon for coarctation of the aorta. The abnormality was isolated in 41 cases (29 p. 100) and associated with ventricular septal defect (VSD) in 58 cases (41 p. 100), with transposition of the great vessels with or without VSD in 16 cases (11.3 p. 100), with cardiac valve disease with or without VSD in 11 cases (7.8 p. 100) or with miscellaneous intracardiac lesions in 15 cases (10.6 p. 100). Resection-anastomosis (Crafoord) was performed in 89 cases (63 p. 100), subclavian flap aortoplasty (Waldhausen) in 36 cases (26 p. 100) and dacron aortoplasty in 16 cases (11 p. 100). Cerclage of the pulmonary artery was combined with one or another of these operations in 65 cases (46 p. 100). Twenty-five patients (17.5 p. 100) died within 30 days of the operation, and 28 patients (24.7 p. 100 of those who survived surgery) died at a later stage. Three infants were lost sight of. Follow-ups ranged from 1 to 13 years (mean: 4.01 years). Fifteen infants (13.3 p. 100 of those who survived surgery) were reoperated upon for recurrence of the coarctation. Four infants (3.5 p. 100) now present with clinical signs of recoarctation and are awaiting treatment.

[Primary tumors of the heart. Diagnostic, anatomic and therapeutic aspects]

Primary cardiac tumours are rare. They are usually benign, the most common ones being left atrial myxomas. The authors report their experience of 16 cardiac tumours operated between 1978 and 1985. The patients were 12 adults and 4 children. The tumours were benign in 14 cases and malignant in 2 cases. Complete (14 cases) or incomplete ablation of the tumour was carried out under cardiopulmonary bypass with an early mortality of 6.25 per cent (1 case) and late mortality of 12.5 per cent (the two malignant tumours). The tumours were identified as myxomas in 11 cases, rhabdomyomas in 2 cases, fibroma in 1 case and malignant sarcomas in 2 cases. The average follow-up period of the 13 survivors is 30 months (range 4 months to 5 years) with excellent clinical and anatomical results. Clinical and paraclinical diagnosis of these tumours does not pose any major problems nowadays because of the reliability of the methods of investigation. However, the nature of the tumour is not always predictable and the operative findings are fundamental, not so much for the treatment which is relatively stereotyped but for the prognosis. Age is not a significant prognostic factor as excellent results may be obtained in the very young and the very old despite a sometimes precarious preoperative clinical condition. The benign or malignant nature of the tumour is the only real factor which affects the prognosis.

[Use of valved tubes in the treatment of ventriculo-pulmonary discontinuity. Long-term results]

Forty five patients, 2 months to 42 years of age, had valved tubes implanted for ventriculo-pulmonary discontinuity. The underlying malformations were: certain forms of Fallot's tetralogy (16 cases), transposition of the great arteries with ventricular septal defect and pulmonary stenosis (8 cases), truncus arteriosus (9 cases), double outlet right ventricle (6 cases), other malformations (4 cases). Hospital mortality (at 30 days) was 31% (14 cases). This was mainly due to technical difficulties related to the large number of palliative procedures and to irreversible pulmonary hypertension, present in 43% of cases with fatal outcomes. Thirty one patients were followed up for 6 months to 7 years (mean 3 +/- 1,6 years). There were 3 late deaths, one during reoperation for a residual shunt. All survivors underwent clinical assessment with hemodynamic control in 17 cases (15 routine control catheterisations). To date it has only been necessary to change one valved tube: a good result was obtained.