Korean J Anesthesiol.  2009 Mar;56(3):265-272. 10.4097/kjae.2009.56.3.265.

Measurement of respiratory pulse transit time variation as an intravascular volume index in simulated hemorrhage

• Jun IG
• Park JY
• Sang BH
• Park JY
• Joo JY
• Hwang GS

• KMID: 2238121
• DOI: http://doi.org/10.4097/kjae.2009.56.3.265

Abstract

BACKGROUND: We examined the usefulness of respiratory pulse transit time (PTT) variation as an intravascular volume index in young, healthy, spontaneous, paced breathing volunteers exposed to simulated central hypovolemia by lower body negative pressure (LBNP).
METHODS
With paced breathing at 0.25 Hz, beat-to-beat finger blood pressure (BP), heart rate (HR), cardiac output (CO), stroke volume (SV), total peripheral resistance (TPR), and PTT were measured non-invasively in 18 healthy volunteers. Graded central hypovolemia was generated using LBNP from 0 to -20, -30, -40, and -50 mmHg. Respiratory PTT variation (PTTV) was calculated as the difference of maximal and minimal values divided by their respective means. Respiratory-frequency PTT variability (PTTRF) using power spectral analysis was also estimated.
RESULTS
During LBNP, SV, CO and PTTRF decreased, but PTT, PTTV and TPR increased significantly. PTTV did not correlate with SV changes (r = -0.08, P = 0.52), but PTTRF (r = 0.58, P < 0.01) and PTT (r = 0.43, P < 0.01) did during progressive hypovolemia.
CONCLUSIONS
PTTRF is more applicable to the changes in intravascular volume than PTT and PTTV, suggesting spectral analysis of PTT might be used as a dynamic preload index in patients with spontaneous and paced breathing condition, which needs further studies.

Keyword

Hypovolemia; Lower body negative pressure; Pulse transit time variation

MeSH Terms

Blood Pressure
Cardiac Output
Fingers
Heart Rate
Hemorrhage
Humans
Hypovolemia
Lower Body Negative Pressure
Pulse Wave Analysis
Respiration
Stroke Volume
Vascular Resistance