Keywords
Photoplethysmography; Intensive Care Units; Computer-Aided Signal Processing; Pulse Wave Analysis; Hemodynamics
Abstract
Background: The non-invasive hemodynamic monitoring by photoplethysmography (PPG) stands out as it is easy to use and it can provide information on hemodynamic parameters at the bedside.
Objective: To compare the main PPG parameters with the age and hemodynamic variables in patients hospitalized in Intensive Care Units (ICUs).
Methods: A cross-sectional study was conducted in the ICU of Hospital Nossa Senhora da Conceição, located in south of Brazil. The following data was collected in the 1st 24h of hospitalization: age, Heart Rate (HR), Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), Mean Arterial Pressure (MAP), Pulse Pressure (PP), Hematocrit (Hct), and variables obtained with PPG: Perfusion Index (PI), Pleth Variability Index (PVI), Crest Time (CT), time between the systolic and diastolic peaks (?T), Augmented Index (AI), τparameter, and arterial aging (b/a). For comparison of the variables, a bivariate linear regression was performed.
Results: 190 individuals were evaluated. Most of them were male (6:5), median age 67.0 (54.0-75.0) years, main reasons for hospitalization: cardiovascular and neurological causes. With regard to PI, we observed a correlation with age (r=-0.163; p= 0.025), DBP (r=0.167; p= 0.021), MAP (r=0.171; p=0.019), and Htc (r=0.205; p=0.005). The PVI showed an association only with HR (r=0.150; p=0.038). The CT was correlated with SBP (r=0.185; p=0.011), PP (r=0.256; p<0.001), and HR (r=-0.651; p<0.001). The ?T interval showed an association only with HR (r=0.187; p=0.010). The AI was correlated with SBP (r=0.173; p=0.017), PP (r=0.195; p=0.007), and HR (r=-0.620; p<0.001). The τ parameter showed an association with SBP (r= 0.147;p= 0.043), PP (r=0.169; p=0.020), and HR (r=-0.649; p<0.001). The b/a index was correlated to age (r=0.254; p<0.001), SBP (r=0.257; p<0.001), MAP (r=0.200; p=0.006), PP (r=0.233; p=0.001), and HR (r=-0.312; p<0.001).
Conclusion: Associations were found, with plausibility in cardiovascular physiology, which allow a general view of the variables implied in the PPG. Such data can provide complementary information for hemodynamic monitoring and clinical judgment of the intensivist.
Citation
de Souza Kock K and Marques JLB. Relationship between the Photoplethysmographic Parameters and Derivation from the Windkessel Model in Hemodynamics in Critically Ill Patients. SM J Cardiolog and Cardiovasc Disord. 2018; 4(1): 1024.