Vol. 280, Issue 6, H2740-H2745, June 2001
Right atrial pressure as measure of ventricular constraint in
newborn lambs
Jean-Claude
Fauchère,
Adrian M.
Walker,
Elizabeth M.
Skuza, and
Daniel A.
Grant
Ritchie Centre for Baby Health Research, Monash Institute of
Reproduction and Development, Monash University, Monash Medical Centre,
Clayton, Melbourne, Victoria 3168, Australia
Although the lungs and pericardium constrain
the heart and limit cardiac output, no method exists to assess this
constraint in sick newborns. We hypothesize that a useful estimate of
ventricular constraint may be obtained by measuring right atrial
pressure (PRA) in the newborn. To test this hypothesis, we
measured PRA, thoracic inferior vena caval pressure
(PIVC; saline-filled catheters), and ventricular constraint
(pericardial pressure, PPER; liquid-containing balloon) in
4-wk-old (neonatal, n = 12) and 3-day-old (newborn, n = 6) anesthetized lambs. The measurements were made
while LV filling pressure was altered (0-20 mmHg) and while
positive end-expiratory pressure (PEEP) was maintained at 2.5 or 15 cmH2O. In all of the lambs, a strong linear relationship
(r) existed between PRA and PPER
(PRA = 1.19 PPER + 0.0, r = 0.99) and between PIVC and
PPER (PIVC = 1.24 PPER + 0.1, r = 0.99; PEEP of 2.5 cmH2O). Similar relationships were also observed with increased PEEP
(PRA = 1.29 PPER
1.2, r = 0.98 and PIVC = 1.32 PPER1.2,
r = 0.97). Because PRA provides an accurate
measure of ventricular constraint in the normal lamb, it may be a
useful measure of ventricular constraint in the sick newborn.
airway pressure; mechanical ventilation; pericardial pressure; positive end-expiratory pressure
