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Objective To propose and validate a new method for estimating cardiac output based on the total arterial compliance (Ct) formula that does not need an arterial waveform and to apply it to brachial oscillometric blood pressure measurements (OBPMs). Methods One hundred subjects with normal heart anatomy and function were included. Reference values for cardiac output were measured with echocardiography, and Ct was calculated with a two-element Windkessel model. Then, a statistical model of arterial compliance (Ce) was used to estimate cardiac output. Finally, the measured and estimated cardiac output values were compared for accuracy and reproducibility. Results The model was derived from the data of 70 subjects and prospectively tested with the data from the remaining 30 individuals. The mean age of the whole group was 43.4 ± 12.8 years, with 46% women. The average blood pressure (BP) was 107.1/65.0 ± 15.0/9.6 mmHg and the average heart rate was 67.7 ± 11.4 beats/min. The average Ct was 1.39 ± 0.27 mL/mmHg and the average cardiac output was 5.5 ± 1.0 L/min. The mean difference in the cardiac output estimated by the proposed methodology vs. that measured by Doppler echocardiography was 0.022 L/min with an SD of 0.626 L/min. The intraclass correlation coefficient was 0.93, and the percentage error was 19%. Conclusion Cardiac output could be reliably and noninvasively obtained with brachial OBPMs through a novel method for estimating Ct without the need for an arterial waveform. The new method could identify hemodynamic factors that explain BP values in an ambulatory care setting.

Introducción: Las unidades de dolor torácico disminuyen la morbimortalidad de los pacientes con síndrome coronario agudo. No obstante, se desconoce su efectividad en el primer nivel de atención con el apoyo de la telecardiología. Objetivo: Evaluar la efectividad de las unidades de dolor torácico sobre los tiempos de atención, la concordancia diagnóstica y la frecuencia de reconsultas a urgencias y hospitalización. Método: Estudio cuasiexperimental de series de tiempo interrumpidas, robusto, que incluyó 20,412 pacientes que consultaron al servicio de urgencias por dolor torácico, antes y después de implementar una unidad de dolor torácico. Se analizaron los cambios en la pendiente, el nivel, la autocorrelación y la varianza de los desenlaces estudiados entre ambos periodos (previo y posterior a las unidades de dolor torácico) a 30 días. Resultados: El promedio de edad fue de 44.9 ± 17.6 años y el 45.8% fueron hombres. La proporción global de pacientes remitidos para hospitalización fue del 9.0%. La pendiente de las tasas de reconsultas a urgencias disminuyó (diferencia: −1.23; intervalo de confianza del 95% [IC95%]: −2.46 a −0.01; p = 0.049) al comparar los dos periodos de observación. Igualmente, la proporción de pacientes remitidos sin síndrome coronario agudo y que finalmente tuvieron este diagnóstico en el tercer nivel de atención disminuyó en el periodo posterior a las unidades de dolor torácico con relación al previo p = 0.020). Conclusiones: Las unidades de dolor torácico incrementaron los egresos de forma segura, con disminución de las reconsultas a urgencias en los siguientes 30 días por la misma causa. Además, mejoró la concordancia diagnóstica del síndrome coronario agudo, sin modificar los tiempos de atención ni la frecuencia de rehospitalización por enfermedad cardiovascular en el seguimiento.Palabras clave: Dolor en el pecho. Síndrome coronario agudo. Servicios médicos de urgencia. Hospitalización. Estudios de series temporales.

Blood pressure (BP) measurements obtained during a twenty-four-hour ambulatory blood pressure monitoring (24 h ABPM) have not been reliably applied to extract arterial hemodynamics. We aimed to describe the hemodynamic profiles of different hypertension (HT) subtypes derived from a new method for total arterial compliance (Ct) estimation in a large group of individuals undergoing 24 h ABPM. A cross-sectional study was conducted, which included patients with suspected HT. Cardiac output, Ct, and total peripheral resistance (TPR) were derived through a two-element Windkessel model without having a pressure waveform. Arterial hemodynamics were analyzed according to HT subtypes in 7434 individuals (5523 untreated HT and 1950 normotensive controls [N]). The individuals mean age was 46.2 ± 13.0 years; 54.8% were male, and 22.1% were obese. In isolated diastolic hypertension (IDH), the cardiac index (CI) was greater than that in normotensive (N) controls (CI: IDH vs. N mean difference 0.10 L/m/m2; CI 95% 0.08 to 0.12; p value <0.001), with no significant clinical difference in Ct. Isolated systolic hypertension (ISH) and divergent systolic-diastolic hypertension (D-SDH) had lower Ct values than nondivergent HT subtype (Ct: divergent vs. nondivergent mean difference −0.20 mL/mmHg; CI 95% −0.21 to −0.19 mL/mmHg; p value <0.001). Additionally, D-SDH displayed the highest TPR (TPR: D-SDH vs. N mean difference 169.8 dyn*s/cm−5; CI 95% 149.3 to 190.3 dyn*s/cm−5; p value <0.001). A new method is provided for the simultaneous assessment of arterial hemodynamics with 24 h ABPM as a single diagnostic tool, which allows a comprehensive assessment of arterial function for hypertension subtypes.