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Critical Care

Open Access

Pulse pressure respiratory variation in experimental hemorrhage and resuscitation

  • GA Westphal1,
  • LF Poli de Figueiredo1,
  • DP Paoli de Almeida1,
  • AG Garrido1 and
  • M Rocha e Silva1
Critical Care20059(Suppl 2):P48

https://doi.org/10.1186/cc3592

Published: 9 June 2005

Keywords

Pulmonary HypertensionStroke VolumeStroke Volume VariationVolume ResuscitationPressure Trace

Background

Pulse pressure (Pp) is strongly coupled with left ventricular stroke volume (SV). Therefore, pulse pressure respiratory variation (ΔPp) reflects SV variation during the respiratory cycle. ΔPp accentuation identifies hypovolemia, and this parameter is recommended to guide volume replacement. Recent reports alert to other clinical situations that accentuate ΔPp, such as pulmonary hypertension and right ventricular dysfunction. ΔPp during and after massive resuscitation has not been determined.

Objective

To observe ΔPp alterations during aggressive volume resuscitation after experimental hemorrhage.

Methods

In 12 ventilated and anesthetized dogs (19 ± 2.5 kg), the CO, MPAP and PAWP were measured by Swan–Ganz catheter; pulmonary resistance (PVR) was calculated using standard formulae. Arterial pressure traces were recorded by a multi-parametric monitor (Datex-Ohmeda, Finland) and ΔPp was calculated according to the following formula: ΔPp (%) = 100 × (Ppins - Ppexp) / [(Ppins + Ppexp) / 2]. Graded hemorrhage (20 ml/min) was produced to a MAP of 40 mmHg. The total shed blood volume was retransfused over 30 min at a rate of 50 ml/min (T10–T30).

Results

During shock we observed the predicted MPAP and PAWP drop and ΔPp amplification, due to a decreased preload, and, consequently, cardiac output decreased. After total shed blood reinfusion and volume expansion (T30), ΔPp increased when compared with either BL (P = 0.02) or T20 (P = 0.003). This increase was associated with increased PVR (P = 0.01) and MPAP (P = 0.05), when compared with BL (Table 1).

Table 1

 

BL

Shocka

T10

T20

T30

PAM (mmHg)

123 ± 8.2

40 ± 4.4

106 ± 5.8

114 ± 7.8

121 ± 5.3

PAPm (mmHg)

18 ± 1.6

11 ± 1.4

26 ± 2.9

27 ± 2.9

24 ± 3.1

PAwP (mmHg)

8 ± 1.3

4 ± 0.9

7 ± 1.3

6 ± 1.1

6 ± 1.1

CO (l/min)

2.4 ± 0.3

0.5 ± 0.1

2.3 ± 0.3

2.9 ± 0.4

2.4 ± 0.3

PVR (dyn.seg/cm5)

333 ± 80

1166 ± 751

656 ± 451

581 ± 349

600 ± 486

ΔPp (%)

13 ± 1.9

23 ± 3.8

16 ± 2.6

13 ± 1.0

17 ± 1.0

aGraded hemorrhage (20 ml/min) was produced to a MAP of 40 mmHg.

Conclusion

We conclude that ΔPp can increase after rapid volume infusion as in hypovolemic states. An acute increase in pulmonary pressure and resistance may be responsible for the observed increment in ΔPp.

Authors’ Affiliations

(1)
Division of Applied Physiology, São Paulo, Brazil; General ICU, Hospital Municipal São José, Heart Institute, InCor, University of São Paulo Medical School, Joinville, Brazil

Copyright

© BioMed Central Ltd 2005

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