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Good Positive and Negative Likelihood Ratios

Good Positive Likelihood Ratio

Poorly Diagnostic Findings

Cardiac Tamponade: Likelihood Ratios

Introduction: Tamponade is an important diagnosis to recognize because of its potential to cause life-threatening hypotension. However, note that hypotension is only present in 24% of patients, at least initially!

[Most of the studies are asking the question: of patients with pericardial effusions, which ones have hemodynamic compromise, i.e. tamponade?]

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Tags: Cardiac Problem Tag this Diagnosis.

The likelihood ratios of findings for Cardiac Tamponade are listed below. See the left navigation bar to change the display.

Good Positive and Negative Likelihood Ratios

Finding +LR-LR Comments, Study
Pulsus Paradoxus Edit 5.80

>12 mmHg. Note that pooled results from additional studies only looking at sensitivity showed a decreased sensitivity of around 82%.

The examiner inflates the sphygmomanometer cuff fully, listens for Korotkoff sounds as the cuff is slowly deflated, and then notes the pressure at which Korotkoff sounds are initially audible only during expiration. As the cuff is further deflated, the examiner notes the pressure at which Korotkoff sounds become audible during expiration and inspiration. The difference between these 2 pressures is the pulsus paradoxus. In cardiac tamponade, the pulsus paradoxus measures greater than 10 mm Hg. Inspiratory diminution in the pulse wave amplitude seen on this arterial tracing demonstrates pulsus paradoxus. A similar phenomenon may be observed on a pulse oximeter waveform.

Study: JAMA. 2007;297:1810-1818.

http://jama.ama-assn.org/cgi/content/full/297/16/1810

Elevated JVP Edit 5.20.1

>3cm

Study: Postgraduate Medical Journal 2000;76:809-813

http://pmj.bmj.com/cgi/content/full/76/902/809

Tachycardia Edit 2.70.2

>100bpm

Study: Postgraduate Medical Journal 2000;76:809-813

http://pmj.bmj.com/cgi/content/full/76/902/809

Good Positive Likelihood Ratio

Finding +LR-LR Comments, Study
Diminished Heart Sounds Edit inf0.8

Study: Postgraduate Medical Journal 2000;76:809-813

http://pmj.bmj.com/cgi/content/full/76/902/809

Poorly Diagnostic Findings

Finding +LR-LR Comments, Study
Hypotension Edit 1.40.9

SBP < 100mmHg

Study: Postgraduate Medical Journal 2000;76:809-813

http://pmj.bmj.com/cgi/content/full/76/902/809

Dyspnea Edit Sensitivity = 88%

specificity not studied

Study: JAMA. 2007;297:1810-1818.

http://jama.ama-assn.org/cgi/content/full/297/16/1810

hearing loss Edit Sensitivity = 25%

specificity not studied

Study: JAMA. 2007;297:1810-1818.

http://jama.ama-assn.org/cgi/content/full/297/16/1810

Chest Pain Edit Sensitivity = 20%

specificity not studied

Study: JAMA. 2007;297:1810-1818.

http://jama.ama-assn.org/cgi/content/full/297/16/1810

Cough Edit Sensitivity = 10%

specificity not studied

Study: JAMA. 2007;297:1810-1818.

http://jama.ama-assn.org/cgi/content/full/297/16/1810