Brief Report
Peripheral tissue oxygenation improves during ED treatment of acute heart failure,☆☆

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Abstract

Objective

The objective of the study was to quantitatively characterize peripheral tissue microvascular oxygenation during emergency department (ED) treatment of acute heart failure (HF).

Methods

This prospective, observational study enrolled acutely decompensated HF patients presenting to an urban ED and stable, asymptomatic HF patients evaluated in an outpatient cardiology clinic. Stable, pre-ED treatment, and post-ED treatment microvascular oxygen extraction ratios (OERMs) were calculated, defined as SaO2 − StO2/0.8*SaO2, where SaO2 is pulse oximetry–derived arterial hemoglobin saturation and StO2 is the tissue hemoglobin oxygen saturation measured with differential absorption spectroscopy. The OERM measurements were analyzed using repeated-measures analysis of variance. Pulse oximetry, patient demographics, HF etiology, serum B-type natriuretic peptide, and hemoglobin were measured along with a visual analogue scale to assess patient baseline characteristics and response to ED treatment (P < .05 was considered significant for all testing).

Results

The OERM for the stable HF group (n = 45) was 0.65 (SE = 0.07). The pre- and posttreatment OERMs for the ED HF group (n = 46) were 0.92 (SE = 0.07) and 0.75 (SE = 0.06), respectively. Whereas the pretreatment ED OERM was higher than the stable patient OERM (P = .001), the posttreatment ED OERM was not significantly different from the stable patient measurement (P = .271).

Conclusions

Oxygen extraction in acute HF is significantly increased, but approaches values found in the stable HF population after ED treatment. The OERM may deserve closer examination as a possible goal-directed variable in the treatment of acute HF.

Introduction

Heart failure (HF) diagnosis and treatment are frequent emergency department (ED) presentations. Emergency department evaluation and treatment have traditionally used global assessors of cardiac function such as serum B-type natriuretic peptide (BNP) measurement, chest radiographs, and urine output. However, they poorly reflect treatment response [1], [2], [3], [4].

From a physiological standpoint, regional tissue oxygenation abnormalities should precede global abnormalities and therefore allow earlier identification of HF severity and response to treatment. Prior work demonstrated that microvascular perfusion is severely altered in HF patients [5]. The microvascular oxygen extraction ratio (OERM) uses noninvasive technology that quantitatively measures microvascular tissue oxygen utilization. Our study objective was to assess microvascular oxygenation in HF patients by measuring peripheral tissue OERM in acutely decompensated HF patients before and after treatment, which were compared with that in stable outpatient HF patients.

Section snippets

Methods

This prospective, observational study was approved by our institutional review board and randomly enrolled nonconsecutive patients from November 2004 to January 2008 at an urban tertiary care hospital. Decompensated HF patients were enrolled after ED presentation. Inclusion criteria included a prior HF diagnosis, serum BNP greater than 100 ng/mL (ADVIA Centaur BNP; Bayer AG, Leverkusen, Germany) and a Boston Heart Failure Criteria score of at least 8 (Appendix 1). These criteria were chosen

Results

Ninety-six patients were enrolled. Three decompensated patients later had non-HF diagnoses and 2 had incomplete data, leaving 45 stable and 46 decompensated patients for analysis. The stable and decompensated groups had similar demographics, except for increased prevalence of hypertension (P < .0l) and hypercholesterolemia (P = .05) and reduced EF (P = .05) in the decompensated group. Mean arterial pressure was also higher in the decompensated group (Table 1). With the exception of vasoactive

Discussion

Aside from serum BNP, HF assessment in the ED setting has not materially changed in 50 years. Physical examination findings, vital signs, chest radiographs, [10] urine output, and patient symptoms have poor accuracy in determining HF severity and response to treatment [1], [11]. Although diagnosing HF has been improved by measuring serum BNP [12], it is only accurate for guiding treatment when high or low, as intermediate levels have less utility [4], particularly in those with chronic HF; and

Limitations

Although the stable and decompensated groups' demographics and comorbidities were similar, hypertension was more prevalent in the decompensated group. This could have affected results, as hypertension can affect arterial and arteriole compliance, potentially impacting microvascular tissue perfusion. Mean arterial pressure and pulse oximetry were measured only twice during each monitoring period. Because, within a 10-minute period, there was very little StO2 variation (1%-2% standard deviation),

Conclusions

This preliminary study of the use of novel technology to assess HF indicates that OERM is increased in patients with acutely decompensated HF and decreases after treatment to values found in the stable HF population. More study is needed to determine its role in the assessment and management of HF in the ED.

References (22)

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    ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2008: the task force for the diagnosis and treatment of acute and chronic heart failure 2008 of the European Society of Cardiology. Developed in collaboration with the Heart Failure Association of the ESC (HFA) and endorsed by the European Society of Intensive Care Medicine (ESICM)

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  • Cited by (10)

    • Presenting phenotypes of acute heart failure patients in the ED: Identification and implications

      2017, American Journal of Emergency Medicine
      Citation Excerpt :

      Ejection fraction may help to subtype AHF patients but it is not especially useful as it provides a crude measure of left ventricular contraction without giving insights into true HD status [34]. Measurement of peripheral tissue-microvascular oxygenation may improve with ED therapy [35]. Natriuretic peptide measurements have been useful in determining the presence and severity of patients presenting with AHF [36] and their decrease with treatments has shown to be associated with reduced time to discharge and total cost of treatment [37].

    View all citing articles on Scopus

    This study was supported by a General Clinical Research Center Clinical Research Feasibility fund (National Center for Research Resources, National Institutes of Health M01 RR00065).

    ☆☆

    Preliminary parts of this study were presented in abstract form at the Society of Academic Emergency Medicine Annual Meeting on May 17, 2007, in Chicago, IL.

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