Girdharry Natasha R, Bentley Robert F, Valle Felipe H, Karvasarski Elizabeth, Osman Sinan, Gurtu Vikram, Kolker Shimon, Mak Susanna
Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
Division of Cardiology, Mount Sinai Hospital/University Health Network, Toronto, Ontario, Canada.
CJC Open. 2021 Apr 30;3(9):1108-1116. doi: 10.1016/j.cjco.2021.04.015. eCollection 2021 Sep.
Obese and overweight body habitus are common among patients undergoing right heart catheterization for suspected pulmonary hypertension, but previous studies have described only patients with severe obesity. This study examined the effect of body habitus on intracardiac pressures, thermodilution cardiac output (TDCO), indirect Fick (iFick) cardiac output (CO), and pulmonary vascular resistance (PVR) in subjects with normal cardiopulmonary hemodynamics.
A retrospective analysis was conducted on healthy volunteers and patients referred for right heart catheterization for dyspnea of unknown origin with normal hemodynamics. Of the 65 subjects (53 ± 14 years; 51% female), 31% were normal weight, 49% were overweight, and 20% had obesity, as defined by a body mass index of 30-39.9 kg/m. Mixed venous oxygen saturations and intracardiac pressures were compared across body mass index categories. Agreement between iFick CO calculated by 3 formulae, and TDCO and PVR was examined.
No differences in intracardiac pressures were observed, but mixed venous oxygen saturations were lower in the obese group. iFick CO underestimated TDCO, particularly with the LaFarge formula, with a systematic difference of 0.33 L/min for every 1 L/min increase in CO. This difference was largest in the obese group-on average by 23% ± 10%, translating to an overestimation of PVR by 34% ± 16% on average.
In individuals without severe obesity, intracardiac pressures are not different, but mixed venous oxygen saturations are lower. Obesity confounds estimations of CO and PVR by iFick methods, which could result in inappropriate hemodynamic classification. These data can inform best practices in hemodynamic assessment of populations with obesity.
肥胖和超重体型在因疑似肺动脉高压而接受右心导管检查的患者中很常见，但以往研究仅描述了重度肥胖患者。本研究探讨了体型对心肺血流动力学正常的受试者的心内压、热稀释心输出量（TDCO）、间接菲克（iFick）心输出量（CO）和肺血管阻力（PVR）的影响。
对健康志愿者和因不明原因呼吸困难且血流动力学正常而接受右心导管检查的患者进行回顾性分析。65名受试者（年龄53±14岁；51%为女性）中，31%体重正常，49%超重，20%肥胖，肥胖定义为体重指数为30 - 39.9kg/m²。比较不同体重指数类别的混合静脉血氧饱和度和心内压。检查了用3种公式计算的iFick CO与TDCO和PVR之间的一致性。
未观察到心内压有差异，但肥胖组的混合静脉血氧饱和度较低。iFick CO低估了TDCO，尤其是使用拉法热公式时，CO每增加1L/min，系统差异为0.33L/min。这种差异在肥胖组中最大——平均为23%±10%，平均导致PVR高估34%±16%。
在无重度肥胖的个体中，心内压无差异，但混合静脉血氧饱和度较低。肥胖会混淆iFick法对CO和PVR的估计，这可能导致血流动力学分类不当。这些数据可为肥胖人群血流动力学评估的最佳实践提供参考。
