We read with interest the report from Piraccini et al. and congratulate them on their
management of severe postpartum haemorrhage in a Jehovah’s Witness patient.
1
Their management of this difficult scenario was guided largely by the Flotrac/Vigileo
cardiac output monitoring system (Edwards Lifesciences, Irvine, CA, USA). Specifically,
optimization of preload was directed by stroke volume variation (SVV) which occurs
due to changes in intrathoracic pressure during the respiratory cycle causing variation
in caval blood flow with subsequent effects on preload. SVV has been validated as
a predictor of fluid responsiveness in mechanically-ventilated patients in a number
of studies.
2
,
3
,
4
Generally, tidal volumes >8 mL/kg and fixed respiratory rates are specified.
5
The rationale for this is the need for consistent change in intrathoracic pressure
from one respiratory cycle to the next, and a sufficiently large change in pressure
to cause a measurable change in stroke volume (SV). It is normally calculated using
the formula: . Currently the literature does not support the use of SVV in spontaneously-breathing
patients as intrathoracic pressure changes are irregular in size and duration.
6
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References
- Cardiac output and fluid replacement in a Jehovah’s Witness with severe postpartum hemorrhage.Int J Obstet Anesth. 2010; 19: 462-463
- Stroke volume variation as a predictor of fluid responsiveness in patients undergoing brain surgery.Anesth Analg. 2001; 92: 984-989
- Changes in arterial pressure during mechanical ventilation.Anesthesiology. 2005; 103: 419-428
- Usefulness of left ventricular stroke volume variation to assess fluid responsiveness in patients with reduced cardiac function.Crit Care Med. 2003; 31: 1399-1404
- Minimally invasive cardiac output monitoring: what evidence do we need?.Br J Anaesth. 2011; 106: 451-453
- Optimal volaemic status and predicting fluid responsiveness.Contin Educ Anaesth Crit Care Pain. 2010; 10: 59-62
- Volume responsiveness.Curr Opin Crit Care. 2007; 13: 549-553
Article info
Publication history
Published online: August 12, 2011
Identification
Copyright
© 2011 Published by Elsevier Inc. All rights reserved.
