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V alidity of Assessing in vivo Cardiac Contractility Using A “Less‐Invasive” Approach during Mechanical Ventilation: Insights from Small and Large Animal Models
Author(s) -
Ahmadian Mehdi,
Wainman Liisa,
Hoiland Ryan,
Williams Alexandra,
Erskine Erin,
Manouchehri Neda,
So Kitty,
Streijger Femke,
Kwon Brian,
Foster Glen,
West Christopher
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.02521
Subject(s) - preload , medicine , cardiology , contractility , hemodynamics , inferior vena cava , blood pressure , mechanical ventilation , anesthesia
Background and Aims End‐systolic elastance (E es ) derived from sequential pressure‐volume (PV) loops acquired during inferior vena cava occlusion (IVCO) is the reference for quantification of in vivo left ventricular (LV) contractile performance. Given the challenges associated with midline laparotomy surgeries in animal models and the barriers of performing such measures in clinical practice, a number of single‐beat estimations of LV contractile function have been proposed. Here, we examined the agreement between two single‐beat estimates of E es obtained from basal LV and arterial hemodynamics in rats and pigs and the E es obtained from IVCO (E es(IVC) ). We also tested whether a novel approach of leveraging the respiratory‐induced oscillations in cardiac PV (i.e., changes in intrathoracic pressure) during mechanical ventilation enables a “naturally” occurring change in cardiac preload and the subsequent estimation of E es (E es(RES) ). Methods 38 Wistar rats (300‐350g; aged 10 wks) and 22 Yucatan mini‐pigs (20‐25 kg, aged 8‐12 wks) were used. Once anesthetized and ventilated, animals were instrumented with 1) a LV PV catheter for assessments of LV E es(IVC) during IVCO and LV hemodynamics, and 2) a femoral arterial catheter to record basal systemic hemodynamics. Basal LV and arterial indices, including end‐systolic volume (ESV), end‐systolic pressure (ESP), and arterial systolic blood pressure (SBP), were averaged over a 30s (rats) or 60s period (pigs). E es(IVC) was measured as the slope of end‐systolic PV relationship (ESPVR). From the basal LV and arterial data we then calculated single‐beat estimation of E es(IVC) , including the ESP and ESV ratio (E esSB1 ), and the ESP (SBP × 0.9) and EDV ratio (E esSB2 ). Estimation of E es(RES) was analogous to E es(IVC) however, respiratory‐induced oscillations in cardiac preload, rather than an IVCO, was used to calculate the slope of the ESPVR. Absolute agreement between metrics was examined using intra‐class correlation coefficients (ICC). Results In rats, while we found a moderate agreement between E es(SB1) (ICC = 0.685, P < 0.001), E es(SB2) (ICC = 0.685, P < 0.001) and E es(IVC), there was excellent agreement between E es(RES) and E es(IVC) (ICC = 0.934 P < 0.001). In pigs, although a moderate agreement was observed between E es(RES) and E es(IVC) (ICC = 0.572, P = 0.033), no agreements were noted between E es(SB1) (ICC = 0.352, P = 0.101), E es(SB2) (ICC = 0.320, P = 0.0741) and E es(IVC) . Conclusion Thesefindings demonstrate that the single‐beat estimates of E es show moderate agreement with E es(IVC) in rats. Utilizing the respiratory‐induced changes in cardiac preload during mechanical ventilation, however, may provide a better less‐invasive approach for estimation of cardiac contractile performance, especially in a small animal model.