Performance improvement on the battlefield.

The Joint Theater Trauma System (JTTS) is a formal system of trauma care designed to improve the medical care and outcomes for combat casualties of Operation Iraqi Freedom and Operation Enduring Freedom. This article describes the JTTS Trauma Performance Improvement Plan and how JTTS personnel use it to facilitate performance improvement across the entire continuum of combat casualty care.

Association of the fourth heart sound with increased left ventricular end-diastolic stiffness.

BACKGROUND: Although the fourth heart sound (S4) is thought to be associated with a stiff left ventricle, this association has never been proven. Recently, single-beat estimation of the end-diastolic pressure volume relationship (EDPVR) has been characterized (P = alphaV(beta)), allowing the estimation of EDPVR in larger groups of patients. We hypothesized that the S(4) is associated with an upward- and leftward-shifted EDPVR, indicative of elevated end-diastolic stiffness. METHODS AND RESULTS: Ninety study participants underwent acoustic cardiographic analysis, echocardiography, and left heart catheterization. We calculated alpha and beta coefficients to define the nonlinear slope of the EDPVR using the single-beat method for measuring left ventricular end-diastolic elastance. In the P = alphaV(beta) EDPVR estimation, alpha was similar (P = .31), but beta was significantly higher in the S(4) group (5.96 versus 6.51, P = .002), signifying a steeper, upward- and leftward-shifted EDPVR curve in subjects with an S(4). The intensity of the S(4) was associated with both beta (r = 0.42, P < .0001) and E/E' / stroke volume index, another index of diastolic stiffness (r = 0.39, P = .0008). On multivariable analysis, beta remained associated with the presence (P = .008) and intensity (P < .0001) of S(4) after controlling for age, sex, and ejection fraction. CONCLUSIONS: The S(4) is most likely generated from an abnormally stiff left ventricle, supporting the concept that the S(4) is a pathologic finding in older patients.

Physiology of the third heart sound: novel insights from tissue Doppler imaging.

BACKGROUND: The third heart sound (S(3)) is thought to be caused by the abrupt deceleration of left ventricular (LV) inflow during early diastole, increased LV filling pressures, and decreased LV compliance. We sought to determine whether the ratio of early mitral inflow velocity to diastolic velocity of the mitral annulus (E/E') could confirm the proposed mechanism of the S(3). METHODS: A total of 90 subjects underwent phonocardiography, echocardiography, tissue Doppler imaging, and left-sided heart catheterization. RESULTS: Phonocardiography detected an S(3) in 21 patients (23%). Subjects with an S(3) had lower ejection fraction (P = .0006) and increased E deceleration rate (P < .0001), E/E' (P < .0001) and filling pressures (P < .0001). The phonocardiographic S(3) confidence score correlated with E/E' (r = 0.46; P < .0001) and E deceleration rate (r = 0.43, P = .0001). Of the echocardiographic variables, only E/E' was independently associated with the S(3) confidence score (P = .009), independently of invasively determined LV filling pressures (P = .001). CONCLUSIONS: The most important determinants of the pathologic S(3) are an increased deceleration rate of early mitral inflow, elevated LV filling pressures, and abnormal compliance of the myocardium as measured by tissue Doppler imaging.

Performance of phonoelectrocardiographic left ventricular systolic time intervals and B-type natriuretic peptide levels in the diagnosis of left ventricular dysfunction.

BACKGROUND: Systolic time intervals measured by echocardiography and carotid artery tracings are validated methods of assessing left ventricular function. However, the clinical utility of phonoelectrocardiographic systolic time intervals for predicting heart failure using newer technology has not been evaluated. METHODS: We enrolled 100 adult patients undergoing left heart catheterization. Participants underwent computerized phonoelectrocardiographic analysis, left ventricular end-diastolic pressure (LVEDP) measurement, transthoracic echocardiographic measurement of left ventricular ejection fraction (LVEF), and B-type natriuretic peptide (BNP) testing. The heart rate-adjusted systolic time intervals included the time from the Q wave onset to peak S1 (electromechanical activation time, EMAT), Q wave onset to peak S2 (electromechanical systole, Q-S2), and peak S1 to peak S2 (left ventricular systolic time, LVST). Left ventricular dysfunction was defined as the presence of both LVEDP >15 mmHg and LVEF <50%. RESULTS: EMAT (r =-0.51; P < 0.0001), EMAT/LVST (r =-0.41; P = 0.0001), and Q-S2 (r =-0.39; P = 0.0003) correlated with LVEF, but not with LVEDP. An abnormal EMAT > or =15 (odds ratio 1.38, P < 0.0001) and EMAT/LVST > or =0.40 (OR 1.13, P = 0.002) were associated with left ventricular dysfunction. EMAT > or =15 had 44% sensitivity, 94% specificity, and a 7.0 likelihood ratio for left ventricular dysfunction, while EMAT/LVST > or =0.40 had 55% sensitivity, 95% specificity, and a 11.7 likelihood ratio. In patients with an intermediate BNP (100-500 pg/mL), the likelihood ratio increased from 1.1 using the BNP result alone to 11.0 when adding a positive EMAT test for predicting left ventricular dysfunction. CONCLUSIONS: Phonoelectrocardiographic measures of systolic time intervals are insensitive but highly specific tests for detecting abnormalities in objective markers of left ventricular function. EMAT and EMAT/LVST provide diagnostic information independent of BNP for detecting patients with left ventricular dysfunction.

Diagnostic characteristics of combining phonocardiographic third heart sound and systolic time intervals for the prediction of left ventricular dysfunction.

BACKGROUND: The third heart sound (S3) and systolic time intervals (STIs) are validated clinical indicators of left ventricular (LV) dysfunction. We investigated the test characteristics of a combined score summarizing S3 and STI results for predicting LV dysfunction. METHODS AND RESULTS: A total of 81 adults underwent computerized phonelectrocardiography for S3 and STI (Audicor, Inovise Medical Inc), cardiac catheterization for LV end-diastolic pressure (LVEDP), echocardiography for LV ejection fraction (LVEF), and B-type natriuretic peptide (BNP) testing. LV dysfunction was defined as both an LVEDP >15 mm Hg and LVEF <50%. The STI measured was the electromechanical activation time (EMAT) divided by LV systolic time (LVST). Z-scores for the S3 confidence score and EMAT/LVST were summed to generate the LV dysfunction index. The LV dysfunction index had a correlation coefficient of 0.38 for LVEDP (P = .0003), -0.53 for LVEF (P < .0001), and 0.35 for BNP (P = .0008). This index had a receiver operative curve c-statistic of 0.89 for diagnosis of LV dysfunction; a cutoff >1.87 yielded 72% sensitivity, 92% specificity, 9.0 positive likelihood ratio, and 88% accuracy. CONCLUSIONS: In this preliminary study, the LV dysfunction index combined S3 and STI data from noninvasive electrophonocardiography, and yielded superior test characteristics compared to the individual tests for the diagnosis of LV dysfunction.

Relationship between accurate auscultation of a clinically useful third heart sound and level of experience.

BACKGROUND: Poor performance by physicians-in-training and interobserver variability between physicians have diminished clinicians' confidence in the value of the third heart sound (S3). METHODS: To determine whether auscultation of a clinically useful S3 improves with advancing levels of experience, we performed a prospective, blinded, observational study of 100 patients undergoing left-sided heart catheterization. Patients underwent blinded auscultation by 4 physicians (each from 1 of 4 different levels of experience), phonocardiography, measurement of blood B-type natriuretic peptide levels, echocardiography for measurement of left ventricular ejection fraction, and cardiac catheterization for measurement of left ventricular end-diastolic pressure. RESULTS: Whereas residents' and interns' auscultatory findings demonstrated no significant agreement with phonocardiographic findings, an S3 auscultated by cardiology fellows (kappa = 0.37; P<.001) and cardiology attendings (kappa = 0.29; P = .003) agreed with phonocardiographic findings. Although the sensitivities of the S3 were low (13%-52%) for identifying patients with abnormal measures of left ventricular function, the specificities were high (85%-95%), with the best test characteristics exhibited by phonocardiography and more experienced physicians. The S3 detected by attendings and fellows was superior in distinguishing an elevated B-type natriuretic peptide level, a depressed left ventricular ejection fraction, or an elevated left ventricular end-diastolic pressure (P = .002-.02 for attendings and .02-.03 for fellows) compared with residents (P = .02-.47) or interns (P = .09-.64). CONCLUSIONS: The S3 auscultated by more experienced physicians demonstrated fair agreement with phonocardiographic findings. Although correlations were superior for phonocardiography, the associations between the S3 and abnormal markers of left ventricular function improved with each level of auscultator experience.

High-sensitivity C-reactive protein and parameters of left ventricular dysfunction.

BACKGROUND: Elevated levels of high-sensitivity C-reactive protein (CRP), an inflammatory marker, have been associated with heart failure. However, it is not known which parameters of left ventricular dysfunction correlate with elevated levels of CRP. METHODS AND RESULTS: In this cross-sectional study of 98 patients referred for cardiac catheterization, we investigated whether commonly used clinical indices of left ventricular dysfunction correlated with CRP levels. CRP levels were elevated to a greater degree in participants with diabetes mellitus (P =.006) and heart failure (P =.003). Increased CRP levels were associated with increased plasma levels of B-type natriuretic peptide (BNP; P =.0001), decreased left ventricular ejection fraction (LVEF; P =.02), and increased left-ventricular end-diastolic pressure (LVEDP; P =.0005). After multivariable adjustment, LVEDP and CRP were independently associated (P =.046). CONCLUSION: CRP is increased in patients with heart failure. Of the clinical parameters of left ventricular dysfunction, direct measurement of left ventricular end-diastolic pressure is most closely associated with CRP.

Association between phonocardiographic third and fourth heart sounds and objective measures of left ventricular function.

CONTEXT: The third (S3) and fourth (S4) heart sounds detected by phonocardiography are considered to represent the criterion standards of the gallop sounds, but their test characteristics have not been explored. OBJECTIVE: To determine the diagnostic test characteristics of the S3 and S4 for prediction of left ventricular dysfunction using a computerized heart sound detection algorithm. DESIGN, SETTING, AND PARTICIPANTS: Prospective study of 90 adult patients undergoing elective left-sided heart catheterization at a single US teaching hospital between August 2003 and June 2004. The mean age was 62 (SD, 13) years (range, 24-90 years) and 61 (68%) were male. Within a 4-hour period, participants underwent computerized heart sound phonocardiographic analysis, cardiac catheterization, transthoracic echocardiography, and blood sampling for assessment of an S3/S4, left ventricular end-diastolic pressure (LVEDP), left ventricular ejection fraction (LVEF), and B-type natriuretic peptide (BNP), respectively. MAIN OUTCOME MEASURES: Diagnostic test characteristics of the computerized phonocardiographic S3 and S4 using markers of left ventricular function as criterion standards. RESULTS: Mean (SD) LVEDP was significantly elevated (18.4 [6.9] mm Hg vs 12.1 [7.3] mm Hg; P<.001), mean (SD) LVEF was reduced (49.4% [20.2%] vs 63.6% [14.8%]; P<.001), and median (interquartile range) BNP was elevated (330 [98-1155] pg/mL vs 86 [41-192] pg/mL; P<.001) in those with an S3, S4, or both compared with patients without a diastolic heart sound. The sensitivities of these heart sounds to detect an elevated LVEDP, reduced LVEF, or elevated BNP were 41%, 52%, and 32% for an S3, and 46%, 43%, and 40% for an S4, respectively. For abnormal levels of the same markers of ventricular function, the specificities of the S3 were 92%, 87%, and 92%, while the specificities of the S4 were 80%, 72%, and 78%, respectively. CONCLUSIONS: Neither the phonocardiographic S3 nor the S4 is a sensitive marker of left ventricular dysfunction. The phonocardiographic S3 is specific for left ventricular dysfunction and appears to be superior to the moderate specificity of the phonocardiographic S4.

The use of propofol in the mechanically ventilated medical/surgical intensive care patient: is it the right choice?

This article provides a review of the use of propofol in the mechanically ventilated patient. The indications for the administration of propofol are presented as well as the contraindications, adverse effects, and nursing care.