| BackgroundPulmonary hypertension is a rare and potentially fatal disorder characterized by rightdysfunction and a progressive decline in cardiac output (CO), which always be evaluatedby invasive hemodynamic monitoring. Thermodilution （TD） and FICK method has beenthe most extensively utilized approach, considered highly accurate, is generally acceptedand trusted. Noninvasive cardiac output measurement (NICOM, Cheetah MedicineCompany, USA) is a new Bioreactance-based technology which is completely noninvasive.Many studies have performed about NICOM in several clinical settings. These studies haveshown to be highly correlated with that measured by TD. However, few studies haveevaluated the accuracy and precision use NICOM compared with standard bolus TDmethod and FICK method in PH. The specific purpose of this single-center study was toevaluate the accuracy and precision of NICOM in PH patients, using TD and FICK methodas reference standard.ObjectiveIn this study, we evaluated NICOM compared to TD and FICK method to measureCO in patients with pulmonary arterial hypertension (PAH) and chronic thromboembolicpulmonary hypertension (CTEPH).MethodsRight heart catheterization was performed in85consecutive patients with confirmedPAH （34with IPAH,13associated with repaired congenital heart disease and18associated with connective tissue disease） or CTEPH. Simultaneous CO measurementswere performed using three different methods (TD, NICOM, FICK) in patients withoutintra-cardiac shunts at baseline (n=85) and after iloprost inhalation (n=71). We comparedthe precision (coefficient of variation) and accuracy of NICOM with TD, usingBland-Altman analysis (bias±95%limits of agreement). In addition, with regard to thepatients who take iloprost inhalation challenge, we compare the correlation and accordance of the change in cardiac output with three methods after iloprost inhalation.Results1. At baseline, the mean CO measured by NICOM, TD and FICK was4.64±1.20L/min,4.63±1.15L/min and4.00±1.40L/min. There was no difference in CO betweenNICOM and TD (p=0.161), but CO according to TD was higher than CO measured by bothNICOM and FICK (p<0.01for both comparisons). NICOM measurements weresignificantly more precise than TD (coefficient of variation2.7±1.94%vs.5.9±3.62%,respectively; p<0.001).2. A significant correlation was seen among all three CO methods: NICOM and TD(r=0.652, p<0.0001), NICOM and FICK (r=0.595, p<0.0001), TD and FICK (r=0.744,p<0.0001). Bland-Altman analyses revealed the following: NICOM compared to TDshowed a mean bias of-0.13with95%limits of agreement of-2.16to2.43. NICOMcompared to FICK showed a mean bias of-0.66with95%limits of agreements of-2.99to1.67. TD compared to FICK showed a mean bias of0.55with95%limits of agreement of-1.50to2.61.3. Following vasodilator challenge, the mean CO was5.53±1.46L/min (NICOM),7.02±1.84L/min (TD), and5.83±1.75L/min (FICK). There was no difference in CObetween NICOM and FICK (p=0.22) but CO measured by TD was higher than COmeasured by both NICOM and FICK (p<0.01for both comparisons). All three COmethods detected a mean increase in CO:1.51±13.29%(NICOM),10.81±15.22%(TD),and4.15±24.5%(FICK). The sensitivity and specificity, respectively, of detecting adirectional change in CO according to each method was:41.67%and100%for NICOM,65.12%and100%for TD, and62.50%and89.29%for FICK. There didn’t see asignificant correlation among all three CO methods in detect the change after iloprostinhaled.ConclusionsCO measured noninvasive via Bioreactance provides precise and accurate COmeasurements compared with TD at baseline. The specificity of detecting a directionalchange in CO according to NICOM after acute vasodilated challenge by iloprost inhalationis desired, but sensitivity is barely satisfactory. NICOM may allow for the noninvasivehemodynamic assessment of patients with PAH and CTEPH. |
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