The respiratory change in preejection period: a new method to predict fluid responsiveness

Abstract

The accuracy and clinical utility of preload indexes as bedside indicators of fluid responsiveness in patients after cardiac surgery is controversial. This study evaluates whether respiratory changes (Delta) in the preejection period (PEP; DeltaPEP) predict fluid responsiveness in mechanically ventilated patients. Sixteen postcoronary artery bypass surgery patients, deeply sedated under mechanical ventilation, were enrolled. PEP was defined as the time interval between the beginning of the Q wave on the electrocardiogram and the upstroke of the radial arterial pressure. DeltaPEP (%) was defined as the difference between expiratory and inspiratory PEP measured over one respiratory cycle. We also measured cardiac output, stroke volume index, right atrial pressure, pulmonary arterial occlusion pressure, respiratory change in pulse pressure, systolic pressure variation, and the Deltadown component of SPV. Data were measured without positive end-expiratory pressure (PEEP) and after application of a PEEP of 10 cmH2O (PEEP10). When PEEP10 induced a decrease of >15% in mean arterial pressure value, then measurements were re-performed before and after volume expansion. Volume loading was done in eight patients. Right atrial pressure and pulmonary arterial occlusion pressure before volume expansion did not correlate with the change in stroke volume index after the fluid challenge. Systolic pressure variation, DeltaPEP, Deltadown, and change in pulse pressure before volume expansion correlated with stroke volume index change after fluid challenge (r2 = 0.52, 0.57, 0.68, and 0.83, respectively). In deeply sedated, mechanically ventilated patients after cardiac surgery, DeltaPEP, a new method, can be used to predict fluid responsiveness and hemodynamic response to PEEP10.

Assessing cardiac preload by the Initial Systolic Time Interval obtained from impedance cardiography

“…Although the power of the study was low, the preliminary results showed significant relationships between the ISTI and the cardiac output at any moment during the fluid No significant or systematic relationships between PTT and CO or ΔPTT and ΔCO were found. This is in contrast with earlier reports [8,9]. Probably, this absence originates from the limited power of this study to detect significances.…”

“…The Initial Systolic Time Interval (ISTI) is defined as the period of time between those R-and C-points. The PTT was obtained by simultaneous ECG recording and arterial pressure wave tracing (P a ) obtained from the radial artery, in concordance with Bendjelid et al [8] and Feissel et al [9]. Both signals are commonly monitored in critically ill patients.…”

“…There is a need for parameters that are able to assess preload and to predict fluid responsiveness in patients in the intensive care unit in order to avoid adverse events like pulmonary oedema. Previous studies have reported that a parameter, equivalent to the pulse transit time (PTT), which is obtained from the ECG and the invasively measured arterial pressure P a , is dependent on the cardiac preload and can be used for this assessment [8,9]. The pulse transit time (PTT) as defined in other studies [11] consists of two components: the PEP, which corresponds to the timing from the onset of ventricular depolarisation to the onset of ventricular ejection, and the ventricular transit time (VTT) which defines the period for the arterial pulse wave to travel from the aortic valve to the peripheral arteries.…”

Fluid and Electrolyte Therapy in Cardiac Surgery

“…Bu amaçla günümüzde değişik dinamik parametreler kullanılmakta olup, bunlardan biri PPV'dir (Şekil 2). PPV ile yapılan birçok çalışmada volüm replasmanına yanıt veren hastalarla, vermeyen hastaların ayırt edilmesinde yararlı olduğu gösterilmiştir (73)(74)(75) . Daha önce yapılan çalışmalarda PPV, arter trasesinin izlendiği monitörden alınan arter trasesi dokümünden manuel olarak hesaplanıyordu veya spesifik kardiyak debi monitörleri olan PiCCO, LiDCO gibi cihazlarla ölçülmekteydi.…”

“…Geçen birkaç yıl da bu parametrelerin dışında başka parametrelerle de sıvı tedavisinin yönlendirilmesine çalışılmıştır. Bunlar arasında vena kava çapı değişikliği (74,82) , solunumla aortik akım değişikliği (83) , ejeksiyon öncesi süre değişiklik-leri (73,75) ve subkütan doku parsiyel oksijen basıncının (PscO 2 ) izlenmesidir (84) .…”