October 1, 1992Journal of Applied Physiology
Role of atrial natriuretic peptide in systemic responses to acute isotonic volume expansion
Key result
Isotonic saline infusion increased mean transcapillary fluid transport from a net reabsorption of 111 ml/h to a net filtration of 1,219 ml/h (P<0.01).
Why the study?
What is the temporal relationship between cardiac filling pressure, plasma ANP, and systemic responses during acute isotonic volume expansion?
Population
7 supine male subjects
Comparison
Infusion of 30 ml/kg isotonic saline at 100 ml/min vs Baseline (control period prior to infusion)
Design
Other
Follow-up
3 hours postinfusion
Authors
Discussion
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Implication
Rapid saline infusion drives net filtration; hypothesis-generating for ANP timing in volume management, larger trials needed.
Key Points
- To evaluate the temporal relationships between cardiac filling pressure, plasma atrial natriuretic peptide levels, systemic vasodilation, fluid filtration, and diuresis during acute volume expansion.
- Administered an infusion of 30 ml/kg isotonic saline at 100 ml/min in seven supine male subjects (N=7) and observed systemic responses over 3 hours postinfusion.
- Measured right atrial pressure using a central venous catheter, plasma atrial natriuretic peptide via radioimmunoassay, and plasma volume changes using Evans blue dye.
- Calculated transcapillary fluid transport and systemic vascular resistance while directly measuring plasma oncotic pressure and urine output.
- Transcapillary fluid transport shifted from a baseline net reabsorption of 111 ± 27 ml/h to net filtration of 1,219 ± 143 ml/h during saline infusion (P < 0.01).
- By the end of infusion, right atrial pressure, heart rate, and plasma volume peaked with increases of 146%, 23%, and 27%, while systemic vascular resistance and plasma oncotic pressure dropped by 29% and 31%, respectively.
- Plasma atrial natriuretic peptide and urine volume reached peak increases of 45% and 390% at 30 minutes postinfusion before most cardiovascular indices normalized by 1 hour.
Structured PICO
What is the temporal relationship between cardiac filling pressure, plasma ANP, and systemic responses during acute isotonic volume expansion?
P
Population
7 supine male subjects undergoing acute isotonic volume expansion and monitored for 3 hours postinfusion.
I
Intervention
Infusion of 30 ml/kg isotonic saline at 100 ml/min
C
Comparator
Baseline (control period prior to infusion)
O
Outcome
Temporal relationship between increases in cardiac filling pressure, plasma ANP concentration, vasodilation, transcapillary fluid transport, and urine volumesurrogate
Main Result
Absolute Event Rate: 1219% vs 111%
p-value: p=<0.01
Acute isotonic volume expansion induces sequential increases in right atrial pressure followed by peaks in plasma ANP and urine volume, highlighting the physiological role of ANP in compensating for circulatory volume overload.
Cite This Study
Watenpaugh et al. (1992) studied this question. Isotonic saline infusion vs. Baseline (control) was evaluated on Transcapillary fluid transport (TFT) (p=<0.01). Isotonic saline infusion increased mean transcapillary fluid transport from a net reabsorption of 111 ml/h to a net filtration of 1,219 ml/h (P<0.01).