EAL

HESI: Congestive Heart Failure Population (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the metabolic, hormonal and hemodynamic characteristics of sodium and water regulation during balanced sodium intake in untreated patients with moderate to severe chronic congestive heart failure.

Inclusion Criteria:

Moderate to severe chronic congestive heart failure, including evidence of cardiomegaly on chest X-ray
Cardiothoracic ratio over 55%.

Exclusion Criteria:

Hypertension
Valvular heart disease
Myocardian Infarction with the previous six months
Recent acute decompensation.

Description of Study Protocol:

Recruitment

Patients were referred for diagnistic evaluation and treatment.

Design

Randomized crossover study

After tapering and discontinuation of diuretic and vasodilator therapy, patients admitted to metabolic unit
Patients received balanced diets for two weeks each, low or moderate sodium (isocaloric, fluid controlled at 2,000ml per day)
Diets were given in randomized order.

Blinding Used

Not described (no placebo tablet for 10meq mentioned).

Intervention

Low (10mEq) vs. moderate (100mEq, acheived by NaCl tablets) sodium diet, each of which included 60mEq to 80mEq potassium (supplemented by 40mEq oral KCl elixir).

Statistical Analysis

Students' paired T-test was used to compare baseline values for each of the two sodium intakes
Linear regression was used for analysis of metabolic data
Two-way ANOVA used to determine the influence of sodium intake, inhibition fo renin-angiotensin system by captopril and position on hemodynamic and hormonal profiles
P<0.05 was considered significant.

Data Collection Summary:

Timing of Measurements

Daily 24-hour urine collections analyzed for volume, sodium, potassium, aldosterone excretion and creatinine clearance
Daily body weights
Daily records of fluid, sodium, potassium and kcal intakes
Blood samples collected at the end of each dietary period (serum sodium, potassium, chlorine, bicaronate, BUN, creatinine)
Plasma renin, norepinephrine and plasma volume were measured at the end of each dietary period.

Dependent Variables

Hemodynamics
Hormonal profiles.

Independent Variables

Sodium intake (10mEq vs. 100mEq)
Positioning (supine vs. tilt)
Inhibition of renin-angiotensin system by captopril (pre- and post-captopril).

Control Variables

Each subject served as his own control
Controlled diets during study
All intakes recorded.

Description of Actual Data Sample:

Initial N: 10 (eight male, two female)
Attrition (final N): 10
Age: 42 years to 74 years
Ethnicity: Not described
Other relevant demographics: Not described
Location: New York City, New York, USA.

Summary of Results:

Key Findings

Hemodynamics: From 10mEq to 100mEq sodium, mean ABP increased form 83±3mmHg to 88±4mmHg; pulmonary artery pressure increased from 27±4mmHg to 36±3mmHg; pulmonary capillary wedge increased from 16±3mmHg to 24±1mmHg (P<0.02 for all).

Metabolic response: A two-kg weight gain was observed going from 10mEq to 100mEq diets (P<0.05). Sodium intake reflected the dietary manipulation (P<0.001) and the difference was apparent in urinary sodium excretion 11±3mEq vs. 63±15meq per 24 hours, P<0.001). Plasma norepinephrine was greater on the 10-mEq, compared to the 100-mEq diet (P<0.01).

During the 100-mEq diet, plasma renin activity (P<0.02) and aldosterone excretion (P<0.01) were suppressed, compared to the 10-mEq diet; this response was reflected in changes of urinary sodium excretion, as there was a significant correlation between both renin and aldosteron with 24-hour urinary sodium excretion (R=-0.768, R=-0.726, P<0.005).

Other Findings

Reversal of vasoconstriction by captopril during 10mEq only indicated renin-dependent mechanism during the 10-mEq diet and a renin-independent mechanism during the 100-mEq diet.

Author Conclusion:

An increase of dietary sodium (from 10mEq to 100mEq) resulted in a two-kg weight gain, supression of renin-angiotensin system and decrease of sympathetic nervous system activity in patients with CHF.

Funding Source:

Government:

NIH

Reviewer Comments:

Additional Quality Table for Intervention Studies

What was the baseline nutrient status (i.e., sodium)? For example the baseline sodium status can be used as an inclusion criterion for entry into study, and recorded in the report of the trial.	BL status not reported.
Was the difference in sodium intake measured between groups? If so, please specify.	Low-sodium diet:230 mg/d (10 mEq) Moderate-sodium diet: 2,300mg/day (100mEq)
Was the difference in sodium status (i.e., change in urinary sodium excretion) measured between groups? If so, please specify.	During 2,300mg/day (100mEq) sodium diet: Neutral sodium balance Na intake: 2,622mg/day (114±9mEq) Na excretion: 2,346mg/day (102±10mEq) Na Retaining: Na intake: 2,691mg/day (117±7mEq) Na excretion: 5,52mg/day (24±10mEq)
Was the status of other nutrient (e.g., potassium and calcium) measured in order to ensure that the test nutrient (i.e., sodium) is the only nutrition-related, limiting factor in the response? If yes, please specify.	Each diet contained 60- to 80mEq potassium, supplemented by 40mEq oral KCl elixir

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		???
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	No
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		???
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	???
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	Yes
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	N/A
	8.6.	Was clinical significance as well as statistical significance reported?	N/A
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes