Archive for the ‘Cardiology’ 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 exam to direct chronic treatment of heart failure

March 3, 2010

Targeting a clinical score to a score of 2 or less based on the Framingham diagnosis of heart failure with the following findings may reduce mortality similarly to targeting a NT-proBNP level and better than usual care:

  • Major findings (1 point each)
  • Minor findings (0.5 point each)
    • Orthopnea
    • Reduction in exercise tolerance
    • Resting heart rate > 100 bpm
    • Hepatomegaly
    • Peripheral edema

This has been added to http://en.citizendium.org/wiki/Heart_failure#Goals.

Citation:
Lainchbury JG, Troughton RW, Strangman KM, Frampton CM, Pilbrow A, Yandle TG, Hamid AK, Nicholls MG, & Richards AM (2009). N-terminal pro-B-type natriuretic peptide-guided treatment for chronic heart failure: results from the BATTLESCARRED (NT-proBNP-Assisted Treatment To Lessen Serial Cardiac Readmissions and Death) trial. Journal of the American College of Cardiology, 55 (1), 53-60 PMID: 20117364

Predicting cardiac arrhythmia among patients with palpitations.

November 22, 2009

ResearchBlogging.org

Does This Patient With Palpitations Have a Cardiac Arrhythmia?

This systematic review by the  Rational Clinical Examination found that an arrhythmia was more likely (LR > 2) if that patient has:

  • A history of cardiac disease (likelihood ratio [LR], 2.03; 95% CI, 1.33-3.11)
  • Palpitations affected by sleeping (LR, 2.29; 95% CI, 1.33-3.94)
  • Palpitations while at work (LR, 2.17; 95% CI, 1.19-3.96)

A arrhythmia was less likely (LR < 0.5) if that patient has:

  • A known history of panic disorder (LR, 0.26; 95% CI, 0.07-1.01)
  • Palpitations lasting less than 5 minutes (LR, 0.38; 95% CI, 0.22-0.63)

Additional findings that need further discussion are:

  • Description by the patient of an irregular heart rate was an independent predictor of a cardiac arrhythmia(PMID: 8629647). The authors of the systematic review did not conclude this finding was helpful because the likelihood ratio, while significant, was within 0.5 to 2.0.
  • An increased number of symptoms suggested psychiatric causes in the univarate, but not multivariate  analysis of Weber  (PMID: 8629647). This finding is part of a theme in general that the more symptoms are present the more likely there is an underlying psychiatric diagnosis in the evaluation of syncope (PMID: 17397948) and symptoms in general in primary care (PMID: 7987511).

This has been added to http://en.citizendium.org/wiki/Palpitation.

Citation:

Thavendiranathan, P., Bagai, A., Khoo, C., Dorian, P., & Choudhry, N. (2009). Does This Patient With Palpitations Have a Cardiac Arrhythmia? JAMA: The Journal of the American Medical Association, 302 (19), 2135-2143 DOI: 10.1001/jama.2009.1673 – PMID 19920238

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

Postural hypotension in patients with syncope

September 18, 2009
ResearchBlogging.org Arch Intern Med 2009 PMID: 19636031

The authors report that in 2106 consecutive patients 65 years or older admitted for syncope, “Postural blood pressure (BP) recording, performed in only 38% of episodes, had the highest yield with respect to affecting diagnosis (18%-26%) or management (25%-30%) and determining etiology of the syncopal episode (15%-21%).”

  • The lower percentages are based on ‘strict criteria’ for abnormal changes:
    • drop in systolic BP of at least 20 mm Hg
    • or
    • drop in diastolic BP of at least 10 mm Hg
  • The higher percentages are based on ‘loose criteria’ for abnormal changes:
    • drop in systolic or diastolic BP of at least 10 mm Hg
    • or
    • systolic BP drop to 90 mm Hg or lower

A systematic review of postural blood pressure measurements has been published by the Rational Clinical Examination (McGee S, Abernethy WB, Simel DL The rational clinical examination. Is this patient hypovolemic? JAMA 1999;281 (11):1022-9. DOI:10.1001/jama.281.11.1022 PMID: 10086438 ) Their meta-analysis concluded that the following changes may occur in normal, euvolemic adults:

  • Pulse increase:11 (95CI: 9-13mm Hg)
  • Systolic blood pressure drop: 4 (95CI: 2 – 6mm Hg)
  • Diastolic blood pressure drop: 5 (95CI: 3 – 8 mm Hg)

Based on the Rational Clinical Examination review, which reveals how difficult it is to interpret orthostatic vital signs and that we cannot simply dichotomize the results into normal and abnormal, I think the strict criteria are better. Even with these criteria, orthostatic vital signs was the most important part of the evaluation for syncope.

This has been added to http://en.citizendium.org/wiki/Syncope and http://wiki.medpedia.com/Clinical:Syncope.

Citation:
Mendu ML, McAvay G, Lampert R, Stoehr J, & Tinetti ME (2009). Yield of diagnostic tests in evaluating syncopal episodes in older patients. Archives of Internal Medicine, 169 (14), 1299-305 PMID: 19636031

The presence of chest pain during EKG

September 18, 2009
ResearchBlogging.org

The presence of chest pain during EKG does not improve its negative predictive value. Academic Emergency Medicine 2009.

The authors detail the findings of 387 consecutive patients with normal electrocardiograms admitted for a chief complaint of chest pain. The authors report that 17% (67/387) of patients had acute coronary syndrome ACS). However, the authors define ACS as:

  • Unstable angina. Either:
    • 70% stenosis (38 patients)
    • positive stress test (1 patient)
  • NSTEMI.
    • Positive troponin (28 patients)

The definition of unstable angina is unusual, differs from the definitions of the American Heart Association, and may include patients without acute ischemia who have a stable stenosis. Focusing on the patients with NSTEMI, the authors found:

  • Among 261 patients with electrocardiogram taken during pain, 18 (7%) had NSTEMI.
  • Among 126 patients with electrocardiogram not taken during pain, 10 (8%) had NSTEMI.
This study independently confirms the findings of an earlier study (PMID 16973638) that the presence of chest pain during a normal electrocardiogram does not adequately exclude NSTEMI among a group of patient that physicians chose to admit the hospital and had a 7% prevalence of NSTEMI.
This does not mean the electrocardiogram cannot help exclude acute coronary syndrome, but means that whether the electrocardiogram is taken during pain is not important.
This does not mean the electrocardiogram cannot exclude acute coronary syndrome in patients at lower risk such as those with unusual pain and no history of ischemic heart disease (PMID 3970650).

This has been added to http://en.citizendium.org/wiki/Acute_coronary_syndrome#Electrocardiogram

Citation:

Turnipseed, S., Trythall, W., Diercks, D., Laurin, E., Kirk, J., Smith, D., Main, D., & Amsterdam, E. (2009). Frequency of Acute Coronary Syndrome in Patients with Normal Electrocardiogram Performed during Presence or Absence of Chest Pain Academic Emergency Medicine, 16 (6), 495-499 DOI: 10.1111/j.1553-2712.2009.00420.x

Detecting elevated LVEDP

February 7, 2009

Diagnostic accuracy of Doppler echocardiography for determining left ventricular diastolic pressure elevation: prospective comparison to chest radiography, serum B-type natriuretic peptide, and chest auscultation. Echocardiography. 2008 Oct;25(9):946-54. PMID: 18771556

In a small study of 56 patients, including 19 with a LVEDP > 15 mm Hg (22 ± 4) by left heart catheterization, no patients had rales, 42% had radiographic pulmonary vascular redistribution, and only 11% had BNP > 100 pg/dL.

These results report even less sensitivity for the chest radiograph than we found in our earlier meta-analysis (http://pubmed.gov/894569). These results are also worse than the original large study of the BNP that found a cutoff of > 50 pg/dL gives high sensitivity (http://pubmed.gov/12124404).

It is unclear what led these patients to their catheterization, but the low sensitivities suggest these patients may have had asymptomatic, chronically elevated LVEDP.