A1 Objective Evaluation of the Efficacy of Various Venous Cannulae

KIT V. AROM, CHERYL ELLESTAD*,

FREDERICK L. GROVER and J. KENTTRINKLE,

San Antonio, Texas

Six venous cannulae (USCI #32, #40, #44; Sams #40, Sarns two-stage cavoatrial (CA); and Ferguson Argyle #40) were tested for efficiency of venous flow during cardiopulmonary bypass, with and without aortic cross-clamping. Each cannula was tested six times in dog models and the data averaged.

The tip of the CA Sarns was positioned in the IVC as recommended. Two #32 USCI caval cannula were placed either with or without caval snaring. The other cannulae (AC) were placed in the right atrium. Arterial flow was constant at 80 ml/kg/min. and pressure averaged 84 mm Hg. The CVP and right atrial pressure (RAP) were recorded. A right ventricular vent (RVV) was placed and the RV excluded from the pulmonary artery. Blood from the right heart which was not picked up by the venous cannula was emptied via the RVV and measured.

Single AC emptied blood from the right heart (RAP = 0-1) better than two caval cannulae (RAP = 0-2). Caval snaring left more blood in the RA (RAP = 2-5) than any single cannula. The CA Sarns did not empty the RA as well (RAP = 2-4) but drained blood from the IVC (CVP = 0) better than other AC'S (CVP= 1-5). Each of the AC performed almost equally well. Aortic cross-clamping eliminated coronary sinus flow and decreased RVV flow.

Therefore, a single atrial cannula is more efficient in draining blood from the right heart when compared to two caval or a caval-atrial cannula. This advantage is negated by aortic cross-clamping.

*By invitation

A2 Special Problems in Management of Tracheostomy in Neonates and Infants

J. ALEX HALLER, JR., J. J. TEPAS*, JAMES D. HEROY*

and DENNIS W. SHERMETA*, Baltimore, Maryland and

Portsmouth, Virginia

Newborn babies and small infants who require tracheostomy often follow a complicated clinical course characterized by frequent sepsis, altered ventilatory dynamics and eventual respiratory decompensation. Many of these problems are avoidable by using a properly placed endotracheal tube during tracheostomy, by using a special surgical technique in the performance of the tracheostomy and by using silastic tracheostomy tubes. Seventy four babies underwent tracheostomy at The Johns Hopkins Hospital and Baltimore City Hospitals between 1963 and 1976. A review of this experience demonstrates the benefits of unhurried, standardized technique and management. In the 48 newborns requiring tracheostomy, no technical difficulties were encountered and no complications occurred as a result of the tracheostomy. In the group of 26 older infants, however, there were significant complications, especially in children undergoing emergency tracheostomy without a previously placed endotracheal tube. Although there were no deaths directly related to tracheostomy, one case of purulent tracheitis and one case of interstitial thyroid hemorrhage were noted at autopsy. Among survivors there was one case of bilateral pneu-mothoraces, two cases of severe subcutaneous emphysema and three cases of postoperative bleeding. Review of the long term complications in this series demonstrates the benefits of the silastic polymer tube. Since its routine use, problems with stomal granulation have almost disappeared. There have been no problems in extubating the very young babies. Our operative technique and intensive care management of these babies will be emphasized as the keys to the improved outcome.

*By invitation