Evaluation of different paediatric venous cannulae using gravity drainage and VAVD: an in vitro study

Optimal Position of Inferior Vena Cava Cannula in Pediatric Cardiac Surgery: A Prospective, Randomized, Controlled, Double-Blind Study

OBJECTIVE

To examine the authors' hypothesis that during the cardiopulmonary bypass (CPB) in children, the inferior vena cava cannula tip placed proximal to the right hepatic vein orifice would produce a higher venous drainage compared with that placed distally.

DESIGN

A prospective, randomized, controlled, double-blind study.

SETTING

Single university hospital.

PARTICIPANTS

Thirty-two patients aged <6years, scheduled for elective cardiac surgery using CPB for congenital heart disease.

INTERVENTIONS

Participants were randomized to 2 groups: the proximal group with the cannula tip placed proximally within 1cm of the right hepatic vein orifice and the distal group with the cannula placed distally within 1cm of the right hepatic vein orifice.

MEASUREMENTS AND MAIN RESULTS

The primary outcome of this study was the perfusion flow rate at the time of establishment of total CPB with cardioplegia. The authors initially planned to enroll 60 patients, but before reaching the target sample size, the authors terminated this study owing to patient safety, and 18 patients in the proximal group and 14 patients in the distal group finally were analyzed. No significant differences in patient characteristics were observed between the 2 groups. The mean perfusion flow rate in the proximal group was significantly greater (2.55 ± 0.27 L/min/m²) than that in the distal group (2.37 ± 0.20 L/min/m², p = 0.04).

CONCLUSION

The inferior vena cava cannula tip placed in the proximal position was clinically superior, compared with a distal placement, in producing higher perfusion flow in children.

Venous drainage--gravity or assisted?

Since the early start of cardiopulmonary bypass, vascular access has been recognized as a main variable for obtaining optimal blood flow during cardiopulmonary bypass. In particular, venous drainage can limit the maximum flow as the wide, low-resistance, collapsible veins are connected with smaller stiff cannulas and tubing. Due to the introduction of long venous cannulas for minimally invasive cardiac surgery and the desire to limit hemodilution during cardiopulmonary bypass, more and more centers have started using assisted venous drainage techniques. This article gives an overview of these techniques, with their respective advantages and disadvantages.

Cardiopulmonary bypass in the immature fetus through novel use of a mini-centrifugal pump

The concept that the natural history of certain heart defects could be positively modified through in utero intervention has stimulated extensive research in fetal cardiac intervention and surgery since the early 1980s. Since the management of certain defects would require the use of cardiopulmonary support, extensive studies have been directed toward the application of a variety of perfusion circuits. The unique features of the fetal patient have directed the focus of many of these designs toward miniaturization of components and minimization of prime volume. Large extracorporeal surface contact areas and prime volumes have been identified as potential contributors to a frequently observed placental dysfunction following fetal cardiopulmonary bypass (CPB). We set out to develop means of CPB using a centrifugal micro-system that would not require supplemental prime volume. We describe the unique application of an adult right heart assist device, primarily used for 'off-pump' coronary revascularization for fetal cardiopulmonary support. Finally, while previous fetal experiments have used late-gestation mature fetuses, we studied more immature fetuses of mid-gestation, relevant to current clinical attempts in fetal therapy.