Changes in cerebral saturation profile in response to mechanical ventilation alterations in infants with bidirectional superior cavopulmonary connection.

OBJECTIVES: To document cerebral saturation in response to alterations in mechanical ventilation in infants with bidirectional superior cavopulmonary connection. DESIGN: Prospective study. SETTING: Pediatric cardiovascular intensive care unit. PATIENTS: Children with functional single ventricle who have undergone bidirectional superior cavopulmonary connection. INTERVENTIONS: We measured cerebral oxygenation using near-infrared spectroscopy in response to three ventilator interventions (change 50% from baseline): a) hyperventilation with increased tidal volume; b) hyperventilation with increased respiratory rate; and c) hypoventilation by decreased respiratory rate. Physiologic variables documented were cerebral oxygenation index (rSO2i), arterial pH, and PCO2. MEASUREMENTS AND MAIN RESULTS: Ten patients (eight males and two females) underwent placement of bidirectional superior cavopulmonary connection. There were no mortalities. The mean age was months 8.6 (+/-2.1) months. Hyperventilation (tidal volume increase) caused an increase in pH from 7.35 to 7.42 (p = .001), a decreased PCO2 from a baseline 45.9 to 33.9 mm Hg. (p = .002), a decrease in rSO2i from 64.4 to 52.0 (p < .001), and a decreased Po2 from 52.8 to 46.9 mm Hg (p = .008). Hyperventilation (respiratory rate increase) caused increased pH from 7.35 to 7.39 (p = .002), decreased PCO2 from a baseline 41 to 37 mm Hg. (p = .021), decreased rSO2i from 65.9 to 56.7 (p = .007), and decreased PO2 from 54.9 to 48.9 mm Hg (p = .006). Hypoventilation (respiratory rate decrease) did not change pH did not change from baseline 7.35. The PCO2 increased from 40.8 to 42, and the rSO2i increased from 64.0 to 68.6 (p = .004). CONCLUSIONS: Hyperventilation can potentially cause a decrease in cerebral oxygenation and should be avoided in children with bidirectional superior cavopulmonary connection. Normoventilation and mild respiratory acidosis, however, preserve cerebral oxygenation in these patients.

Anesthetic management and outcome of complex late arterial-switch operations for patients with transposition of the great arteries and a systemic right ventricle.

OBJECTIVE: For patients with transposition of the great arteries and a systemic right ventricle, complex late arterial-switch operations (double switch, switch conversion, Senning-Rastelli) after the newborn period have been described recently to restore the morphologic left ventricle to the systemic circulation. The purpose of this study was to describe the anesthetic management and perioperative outcome of this group of patients and to compare them with a control group of patients who had primary arterial-switch operations in the neonatal period. DESIGN: Retrospective database and medical record review with 3:1 control:case ratio. SETTING: Tertiary care academic children's hospital. PARTICIPANTS: Patients undergoing complex late-arterial switch operations after the newborn period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Thirteen patients were identified in the complex late-switch group and 43 in neonatal arterial-switch group. There were no perioperative deaths, no new gross neurologic deficits, and all patients were discharged home in both groups. Anesthetic and bypass times were significantly longer in the late-switch group (745 v 558 minutes, p < 0.001, and 382 v 243 minutes, p < 0.001, respectively). Transfusion requirements were similar between the groups. The incidence of arrhythmia (92% v 9%, p < 0.001), use of pacing systems (69% v 9%, p < 0.001), cardioversion (15% v 0%, p = 0.05), and pharmacologic treatment of arrhythmias (69% v 0%, p < 0.01) intraoperatively were significantly higher in the complex late-switch group. CONCLUSIONS: Patients presenting for complex late corrective operations for transposition of the great arteries require long and complex anesthetics. Despite these challenges, perioperative outcomes are excellent.

Changes in respiratory mechanics among infants undergoing heart surgery.

UNLABELLED: Children with excessive pulmonary blood flow (PBF) from congenital heart disease have abnormal respiratory mechanics. Exposure to hypothermic cardiopulmonary bypass (CPB) adversely affects lung function. We designed this study of 106 patients to determine the changes in respiratory mechanics in infants younger than 1 yr undergoing heart surgery. Dynamic respiratory compliance (Cdyn) and total respiratory resistance (Rrs) were measured before surgical incision, after sternal closure in the operating room, and after arrival in the intensive care unit. The following data were recorded: age, weight, preoperative pulmonary infiltrates, preoperative mechanical ventilation, evidence of increased PBF before surgery, duration of CPB, duration of aortic cross-clamp, duration of deep hypothermic circulatory arrest, use of steroids, and volume of ultrafiltrate removed. Repeated-measures analysis of variance with covariate analysis was used to determine the effect of each covariate on Cdyn and Rrs at the three time periods. Rrs improved after cardiac surgery correcting increases in PBF, and this was most pronounced in neonates. Among infants with normal or reduced PBF, cardiac surgery with CPB led to a reduction in Cdyn. We consider that the benefits of surgical correction of pulmonary overcirculation outweigh the negative effects of CPB on respiratory mechanics. IMPLICATIONS: The benefits of surgical correction of pulmonary overcirculation outweigh the negative effects of cardiopulmonary bypass on respiratory mechanics in infants.