Capnodynamic determination of cardiac output in hypoxia-induced pulmonary hypertension in pigs

Abstract

Background: Effective pulmonary blood flow (CO EPBF) has recently been validated for its ability to measure cardiac output (CO) in children and animals. This study compared CO EPBF with the Fick method (CO Fick) and CO measurements using an invasive pulmonary artery flow probe (CO TS). The aim of the study was to validate CO EPBF against these reference methods in a porcine model of hypoxia-induced selective pulmonary hypertension. Methods: Ten anaesthetised mechanically ventilated piglets (median weight 23.9 kg) were exposed to a hypoxic gas mixture inducing selective pulmonary hypertension. Pulmonary hypertension was subsequently reversed with inhaled nitric oxide. Simultaneous recordings of CO EPBF , CO Fick , and CO TS were performed throughout the protocol and examined for agreement and trending ability. Results: Overall bias (Bland-Altman) between CO EPBF and CO TS was 0.2 L min À1 (limits of agreement À0.5 and þ0.9 L min À1) with a mean percentage error of 25%. Overall bias between CO EPBF and CO Fick was À0.1 L min À1 (limits of agreement À0.9 and þ0.6 L min À1) and a mean percentage error of 25%. The concordance rate was 86% for CO EPBF when compared with CO TS using a 10% exclusion zone. Conclusions: Estimation of CO with CO EPBF results in values very close to the gold standard reference methods CO Fick and CO TS. CO EPBF appears to be an accurate tool for monitoring absolute values and changes in CO during hypoxia-induced pulmonary hypertension and inhaled nitric oxide treatment.

Performance of a capnodynamic method estimating cardiac output during respiratory failure - before and after lung recruitment

“…Previous animal studies and our overall data show conflicting results in terms of higher PEEP (increased lung volume) and accuracy of the CO EPBF . Interestingly, in a recent clinical study (manuscript) where CO EPBF was compared to transpulmonary 114 (6) 124 (4) 115 (4) 133 (9) 118 (8) 117 7124 (12) 116 (10) 133 (13) MAP (mmHg) 74 (10) 73 (9) 57 (9) 83 (15) 78 (11) 75 (11) 83 (16) 60 (11) 90 (18) 89 (8) mPAP (mmHg) 312 (17) 310 (12) 310 (12) 310 (12) 310 (12) 309 (11) 310 (12) 310 (12) 310 (12) 310 (13) RR ( 19 219 215 215 215 215 ( thermodilution during open abdominal surgery, no over estimation was observed even at high PEEP levels (up to 20 cmH 2 O) [24]. The current experimental protocol using the improved capnodynamic method departs from our previous study [6] in three ways.…”

“…As previously described, the capnodynamic method with inspiratory holds (CO EPBFinsp ) showed acceptable performance in animals with low shunt [ 4 ], however when the animals were subjected to lavage-induced lung injury both accuracy and precision were affected [ 6 ]. After refinement of the method with the obliged holds inserted in expiration (CO EPBFexp ) instead of inspiration the performance in a porcine model with healthy lungs improved with sustained good trending ability during hemodynamic and ventilatory challenges [ 5 , 7 – 9 ]. In addition, CO EPBFexp has been shown to provide stable CO monitoring in healthy infants undergoing cleft-lip surgery [ 8 ].…”

Comparison between capnodynamic and thermodilution method for cardiac output monitoring during major abdominal surgery

“… 10 In addition, CO EPBF has been shown to provide stable CO monitoring in healthy infants undergoing cleft-lip surgery, and in piglets during hypoxic vasoconstriction. 11 , 12 …”

Blood pressure and flow in pediatric anesthesia: An educational review

“…30,31 Furthermore, the capnodynamic method has been shown to adequately estimate CO pediatric animal models of pulmonary hypertension. 32 The method has the advantage of being available in nearly all intubated and mechanically ventilated subjects. The prerequisite of mandatory controlled mechanical ventilation is, however, also one of the main limitations of the method.…”