Changes in left ventricular ejection time and pulse transit time derived from finger photoplethysmogram and
Paul M Middleton1, Gregory S H Chan, Emma O'Lone
1Emergency Department, Prince of Wales Hospital, Sydney, NSW, Australia. pmmiddleton@ambulance.nsw.gov.au
Objectives:
Early identification of haemorrhage is difficult when a bleeding site is not apparent. This study explored the potential use of the finger photoplethysmographic (PPG) waveform derived left ventricular ejection time (LVET(p)) and pulse transit time (PTT) for detecting blood loss, by using blood donation as a model of controlled mild to moderate haemorrhage.
Methods:
This was a prospective, observational study carried out in a convenience sample of blood donors. LVET(p), PTT and R-R interval (RRi) were computed from simultaneous measurement of the electrocardiogram (ECG) and the finger infrared photoplethysmogram obtained from 43 healthy volunteers during blood donation. The blood donation process was divided into four stages: (i) Pre-donation (PRE), (ii) first half of donation (FIRST), (iii) second half of donation (SECOND), (iv) post-donation (POST).
Results And Conclusions:
Shortening of LVET(p) from 303+/-2 to 293+/-3 ms (mean+/-SEM; P<0.01) and prolongation of PTT from 177+/-3 to 186+/-4 ms (P<0.01) were observed in 81% and 91% of subjects respectively when comparing PRE and POST. During blood donation, progressive blood loss produced falling trends in LVET(p) (P<0.01) and rising trends in PTT (P<0.01) in FIRST and SECOND, but a falling trend in RRi (P<0.01) was only observed in SECOND. Monitoring trends in timing variables derived from non-invasive ECG and finger PPG signals may facilitate detection of blood loss in the early phase.
Related Concept Videos
Cardiovascular System Abnormal Findings I: Inspection and Palpation
Abnormal findings observed during an inspection
Pulse
The pulse serves as a clinical indicator...
Special considerations while measuring pulse
Pulse rhythm
Conversely, an irregular pulse pattern is termed dysrhythmia, stemming from disruptions in cardiac muscle...
Electrocardiogram
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...
Assessment of the Cardiovascular System III: Palpation
Jugular Venous Pressure (JVP) Measurement
Position the patient at a thirty- to forty-five-degree angle or in a semi-fowler's position. Look for the highest point of pulsation in the internal jugular vein and measure the vertical distance to the angle of Loius or sternal angle. A normal JVP is 3-4 cm above the...

