Archive for the ‘Critical care’ Category

Distinguishing categories of shock

February 11, 2011
Patients: 68 adults with more than  30 minutes of systolic blood pressure <90 mmHg
Examination: performed by medicine house officers.
Outcome: Category of shock classified by a single, blinded, experienced clinician using published consensus guidelines when available.
Results: The combination of estimation of the skin temperature (patient’s hand cooler than the examiner’s hand) and central venous pressure (CVP >7 cm) correctly categorized 52 of 68 cases (accuracy = 76%).
Although not explicitly stated, the categorization seems to be:
  • Septic shock (37 patients): warm hands; CVP  < 8 cm.
  • Cardiogenic shock (18 patients): cool hands, CVP  > 7 cm.
  • Hypovolemic shock (13 patients): cool hands, CVP  < 8 cm.

Comment: The authors used an odd definition of pulse pressure, “same/wider vs. thinner than examiner’s”, which may have prevented this sign from being significant. Other studies have found that a proportional pulse pressure < 25% is predictive of poor cardiac physiology (PMID: 2913385; PMID: 11420761)

This has been added to http://en.citizendium.org/wiki/Shock_(physiology).

Citation

Vazquez R, Gheorghe C, Kaufman D, & Manthous CA (2010). Accuracy of bedside physical examination in distinguishing categories of shock: a pilot study. Journal of hospital medicine : an official publication of the Society of Hospital Medicine, 5 (8), 471-4 PMID: 20945471

Using the physical examination to predict response to fluid bolus.

March 18, 2010

This post, and the last post to ClinDx about heart failure, use the physical examination not as a traditional diagnostic test, but rather to help predict response to treatment.

The current study shows that an increase of pulse pressure of ≥ 9% (as measured by a radial artery catheter) can predict an increase in stroke volume after 500 cc of  6% hydroxyethyl starch among patients with severe sepsis or pancreatitis.  The differences in the areas under the ROC curves were no significantly different among the three findings in the table.

Predicting increase in cardiac stroke volume after intravenous infusion of 500 cm of fluids
Finding after passive leg raising Sensitivity Specificity
Increase ≥ 9% in pulse pressure as measured by radial arterial catheter 79% 85%
Increase ≥ 8% in femoral artery blood flow as measured by Doppler ultrasonography 86% 80%
Increase ≥ 10% in stroke volume as measured by bedside echocardiography 86% 90%

A limitation is that the pulse pressure was measured by radial artery catheter. Presumably, an auscultated blood pressure would perform similarly, but this is not certain.

This has been added to http://en.citizendium.org/wiki/Head-down_tilt.

Predicting low cardiac index and central oxygenation

November 22, 2009

ResearchBlogging.org

Association of physical examination with pulmonary artery catheter parameters in acute lung injury
The authors found that physical findings had good specificity in predicting low cardiac index (CI) and low central oxygenation; however, at the low prevalence of low CI in this study, even when all three physical findings were present, the positive predictive value was 40%.
This cross sectional study looked at three physical findings (delayed capillary refill time, knee mottling, and cool skin temperature) in predicting cardiac index,  central venous oxygen saturation (ScvO2 – a quality measure of IHI), and mixed venous oxygen saturation (SvO2) among 392 patients with acute lung injury studied by ARDSNet.
Results:

For cardiac index < 2.5 (similar results for the measures of oxygenation):

Sensitivity Specificity Predictive values at prevalence of 8%
Positive Negative
Any one of three findings* present 52% 78% 17% 95%
All three findings* present 12% 98% 40% 93%
* Findings are: delayed capillary refill time, knee mottling, and cool skin temperature.
Did not look at proportional pulse pressure < 25% which has previously been found to be predictive (PMID: 2913385; PMID: 11420761)
The Rational Clinical Examination previously concluded that the capillary refill time did not help predict hyovolemia in adults (PMID: 10086438).
Nice to see that the National Institutes of Health/National Heart, Lung and Blood Institute Acute Respiratory Distress Syndrome Network (ARDSNet) is interested in the physical examination.

Citation:
Grissom CK, Morris AH, Lanken PN, Ancukiewicz M, Orme JF Jr, Schoenfeld DA, Thompson BT, & National Institutes of Health/National Heart, Lung and Blood Institute Acute Respiratory Distress (2009). Association of physical examination with pulmonary artery catheter parameters in acute lung injury. Critical care medicine, 37 (10), 2720-6 PMID: 19885995