Hemodynamic effects of periodic obstructive apneas in sedated pigs with congestive heart failure

Ling Chen, Quihu Shi, Steven M. Scharf*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Because of similar physiological changes such as increased left ventricular (LV) afterload and sympathetic tone, an exaggerated depression in cardiac output (CO) could be expected in patients with coexisting obstructive sleep apnea and congestive heart failure (CHF). To determine cardiovascular effects and mechanisms of periodic obstructive apnea in the presence of CHF, 11 sedated and chronically instrumented pigs with CHF (rapid pacing) were tested with upper airway occlusion under room air breathing (RA), O2 breathing (O2), and room air breathing after hexamethonium (Hex). All conditions led to large negative swings in intrathoracic pressure (-30 to -39 Torr) and hypercapnia (PCO2 ~60 Torr), and RA and Hex also caused hypoxia (to ~42 Torr). Relative to baseline, RA increased mean arterial pressure (from 97.5 ± 5.0 to 107.3 ± 5.7 Torr, P < 0.01), systemic vascular resistance, LV end-diastolic pressure, and LV endsystolic length while it decreased CO (from 2.17 ± 0.27 to 1.52 ± 0.31 l/min, P < 0.01), stroke volume (SV; from 23.5 ± 2.4 to 16.0 ± 4.0 ml, P < 0.01), and LV end- diastolic length (LVEDL). O2 and Hex decreased mean arterial pressure [from 102.3 ± 4.1 to 16.0 ± 4.0 Torr (P < 0.01) with O2 and from 86.0 ± 8.5 to 78.1 ± 8.7 Torr (P < 0.05) with Hex] and blunted the reduction in CO [from 2.09 ± 0.15 to 1.78 ± 0.18 1/ml for O2 and from 2.91 ± 0.43 to 2.50 ± 0.35 1/ml for Hex (both P < 0.05)] and SV. However, the reduction in LVEDL and LV end-diastolic pressure was the same as with RA. There was no change in systemic vascular resistance and LVEDL during O2 and Hex relative to baseline. In the CHF pigs during apnea, there was an exaggerated reduction in CO and SV relative to our previously published data from normal sedated pigs under similar conditions. The primary difference between CHF (present study) and the normal animals is that, in addition to increased LV afterload, there was a decrease in LV preload in CHF contributing to SV depression not seen in normal animals. The decrease in LV preload during apneas in CHF may be related to effects of ventricular interdependence.

Original languageEnglish (US)
Pages (from-to)1051-1060
Number of pages10
JournalJournal of applied physiology
Volume88
Issue number3
DOIs
StatePublished - Mar 2000

Funding

Keywords

  • Cardiac output
  • Hexamethonium
  • Hypoxia
  • Obstructive apnea

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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