Key result
Pulse transit time significantly increased during blood loss (from 0.2895s to 0.3148s, P<0.05) and decreased during water supply (to 0.2792s, P<0.05), demonstrating its potential as a non-invasive indicator for heavy blood loss.
Why the study?
Does non-invasive monitoring of Pulse Transit Time (PTT) detect heavy blood loss during surgical operations in patients undergoing surgery?
Observational (n=30)
No
Does non-invasive monitoring of Pulse Transit Time (PTT) detect heavy blood loss during surgical operations in patients undergoing surgery?
Absolute Event Rate: 0.3148% vs 0.2895%
p-value: p=<0.05
Pulse transit time derived from ECG and PPG waveforms can serve as a non-invasive physiological indicator of blood loss and fluid shifts during surgical operations.
PTT changes may track blood loss in surgery; leaves open validation before clinical adoption.
The main contribution of this paper is the use of non-invasive measurements such as electrocardiogram (ECG) and photoplethysmographic (PPG) pulse oximetry waveforms to develop a new physiological signal analysis technique for detecting blood loss during surgical operation. Urological surgery cases were considered as the control group due to its generality, and cardiac surgery as experimental group since it involves blood loss and water supply. Results show that the control group has the tendency of a reduction of the pulse transient time (PTT), and this indicates an increment in the blood flow velocity changes from slow to fast. While for the experimental group, the PTT indicates high values during blood loss, and low values during water supply. Statistical analysis shows considerable differences (i.e., P <0.05) between both groups leading to the conclusion that PTT could be a good indicator for monitoring patients' blood loss during a surgical operation.
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Wang et al. (2012) conducted an observational in Surgical operation (urological or cardiac) (n=30). Blood loss and water supply vs. Baseline (pre-blood loss) and control group (urological surgery) was evaluated on Pulse Transit Time (PTT) during blood loss (p=<0.05). Pulse transit time significantly increased during blood loss (from 0.2895s to 0.3148s, P<0.05) and decreased during water supply (to 0.2792s, P<0.05), demonstrating its potential as a non-invasive indicator for heavy blood loss.
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