A-line and volume

Wednesday August 16, 2006
Bedside Tip - Need volume?


Even Before you start monitoring CVP (central venous pressure) or waiting for urine to start trickle in bag with IVF bolus, just a glance at ARTERIAL WAVEFORM may tell you that your patient is volume depleted. The arterial trace may reveal the intravascular fluid depletion by an exaggeration of the decrease in pressure (pulsus paradoxus) that normally occurs during or shortly after inspiration. A difference of 10 mm Hg or higher from inspiration to expiration identifies pulsus paradoxus. It may even occur before parameters such as central venous pressure, blood pressure, or urine output substantially decrease, in both ventilated or spontaneously breathing patient 1.

Interesting question raised in one of the article related to this topic 1 : Whether a goal-directed therapy taking into account the assessment of the respiratory variation in arterial pressure may improve the outcome of mechanically ventilated patients with shock.....?. Click reference # 1 to see waveforms and algorithm.


Related: We found 2 good review articles on basic understanding of arterial waveform to distribute among residents and new fellows (its august - right?)

1. HEMODYNAMIC MONITORING: DYNAMIC RESPONSE ARTIFACTS - Michael L. Cheatham, MD, FACS, FCCM - Director, Surgical Intensive Care Units, Orlando Regional Medical Center, Orlando, Florida.

2. Monitoring Arterial Blood Pressure: What You May Not Know - Ref: Critical Care Nurse. 2002;22: 60-79




Reference: click to get full article

1. Changes in Arterial Pressure during Mechanical Ventilation. Anesthesiology. 103(2):419-428, August 2005. Michard, Frederic M.D., Ph.D.