SummaryPulse contour methods determine cardiac output semi-invasively using standard arterial access. This study assessed whether cardiac output can be determined non-invasively by replacing the intra-arterial pressure input with a non-invasive finger arterial pressure input in two methods, Nexfin CO-trek Ò and Modelflow Ò , in 25 awake patients after coronary artery bypass surgery. Pulmonary artery thermodilution cardiac output served as a reference. In the supine position, the mean (SD) differences between thermodilution cardiac output and Nexfin CO-trek were 0.22 (0.77) and 0.44 (0.81) l.min )1 , for intra-arterial and non-invasive pressures, respectively. For Modelflow, these differences were 0.70 (1.08) and 1.80 (1.59) l.min, respectively. Similarly, in the sitting position, differences between thermodilution cardiac output and Nexfin CO-trek were 0.16 (0.78) and 0.34 (0.83), for intra-arterial and non-invasive arterial pressure, respectively. For Modelflow, these differences were 0.58 (1.11) and 1.52 (1.54) l.min )1 , respectively. Thus, Nexfin CO-trek readings were not different from thermodilution cardiac output, for both invasive and non-invasive inputs. However, Modelflow readings differed greatly from thermodilution when using non-invasive arterial pressure input.

The prototype device closely follows arterial pressure changes in children. However, in a considerable number of attempts, obtaining a signal was time-consuming or unsuccessful. This technique seems promising but requires further technical development.

Beta type continuous noninvasive arterial blood pressure monitoring using a finger cuff with brachial arterial waveform reconstruction seems reliable in hemodynamically stable critically ill children.

ABSTRACT:Our goal was to study the feasibility of continuous noninvasive finger blood pressure (BP) monitoring in very young children, aged 0 -4 y. To achieve this, we designed a set of smallsized finger cuffs based on the assessment of finger circumference. Finger arterial BP measured by a volume clamp device (Finapres technology) was compared with simultaneously measured intra-arterial BP in 15 very young children (median age, 5 mo; range, 0 -48), admitted to the intensive care unit for vital monitoring. The finger cuff-derived BP waveforms showed good resemblance with the invasive arterial waveforms (mean root-mean-square error, 3 mm Hg). The correlation coefficient between both methods was 0.79 Ϯ 0.19 systolic and 0.74 Ϯ 0.24 diastolic. The correlation coefficient of beat-to-beat changes between both methods was 0.82 Ϯ 0.18 and 0.75 Ϯ 0.21, respectively. Three measurements were related to measurement errors (loose cuff application; wrong set-point). Excluding these erroneous measurements resulted in clinically acceptable measurement bias (Ϫ3.8 mm Hg) and 95% limits of agreement (Ϫ10.4 to ϩ 2.8 mm Hg) of mean BP values. We conclude that continuous finger BP measurement is feasible in very young children. However, cuff application is critical, and the current set-point algorithm needs to be revised in very young children. I n human adults, continuous noninvasive finger blood pressure (BP) measurement has been available using the Finapres (FINger Arterial PRESsure) device (1). It has been widely used in the investigation of autonomic function in adults and has proven to be a reliable substitute for intraarterial measurements (2). The device is based on a photoplethysmographic system applied to the finger and provides beat-to-beat arterial finger BP with the use of the volume clamp technique of Peñáz (3). The Finapres method is evaluated in children aged 6 -16 y, showing similar accuracy as that in adults (4,5). Because no appropriate finger cuff exists for the children below 6 y of age, the applicability of the method is limited in this age group. Still, in the evaluation of pediatric patients with cardiovascular abnormalities (e.g. sepsis) or autonomic dysfunction (e.g. syncope), it is desirable to have continuous BP measurements.Recently, there are several publications in which investigators performed BP measurements with the Finapres method in newborns by simply applying the (commercially available) finger cuff around the wrist (6 -9). However, Finapres was not designed for BP measurements on the wrist. First, the method of volume clamping is only validated with an appropriate cuff applied to the midphalanx of the finger. Second, the difference between fingers of adults and children may not only be the size but also the physiologic properties of the arteries and thus need an adaptation of the autocalibration (algorithm). Third, applying the cuff around the wrist will result in venous congestion of the whole hand and not just the fingertip, and will ultimately limit its clinical applicability. Measurements on...

Ultra-weak photon emission (UPE) is a general feature of living -biological systems. To gain further insights into the origin of UPE and its physiological significance, the aim of the present study was to investigate the connection between hemodynamics (HD), oxygenation (OX), and UPE. Therefore, during venous and arterial occlusion (VO, AO), changes of UPE and surrogates of HD as well as OX were measured simultaneously using two photomultipliers and near-infrared spectroscopy, respectively. We showed that (1) changes in UPE correlate significantly nonlinearly with changes in oxyhemoglobin, indicating a complex association between UPE and tissue HD/OX; (2) UPE decreases significantly during AO but not during VO; (3) UPE increases significantly after AO; and (4) the view that ROS are the source of UPE is generally supported by the present study, although some findings remain unexplained in the context of the theory of ROS-mediated UPE generation. In conclusion, the present study revealed new insights into the interplay between HD, OX, and UPE and opens up new questions that have to be addressed by future studies. Abstract: Ultra-weak photon emission (UPE) is a general feature of living biological systems. To gain further insights into the origin of UPE and its physiological significance, the aim of the present study was to investigate the connection between hemodynamics (HD), oxygenation (OX), and UPE. Therefore, during venous and arterial occlusion (VO, AO), changes of UPE and surrogates of HD as well as OX were measured simultaneously using two photomultipliers and near-infrared spectroscopy, respectively. We showed that (1) , indicating a complex association between UPE and tissue HD/OX; (2) UPE decreases significantly during AO but not during VO; (3) UPE increases significantly after AO; and (4) the view that ROS are the source of UPE is generally supported by the present study, although some findings remain unexplained in the context of the theory of ROS-mediated UPE generation. In conclusion, the present study revealed new insights into the interplay between HD, OX, and UPE and opens up new questions that have to be addressed by future studies.