The cardiovascular effects of normobaric hyperoxia in patients with heart rate fixed by permanent pacemaker.
Anaesthesia
; 65(2): 167-71, 2010 Feb.
Article
em En
| MEDLINE
| ID: mdl-20003116
ABSTRACT
To investigate whether the established reductions in heart rate and cardiac output with hyperoxia in humans are primary effects or secondary to increases in systemic vascular resistance, we paced the hearts of nine patients with permanent pacemakers at a fixed rate when breathing either medical air (inspired O(2) fraction 0.21) or oxygen (inspired O(2) fraction 0.80) in a randomised, double-blind fashion. A thoracic bio-impedance machine was used to measure heart rate, stroke volume and blood pressure and calculate cardiac index and systemic vascular resistance index. Oxygen caused no change in cardiac index (p = 0.18), stroke index (p = 0.44) or blood pressure (p = 0.52) but caused a small (5.5%) increase in systemic vascular resistance index (p = 0.03). This suggests that hyperoxia has no direct myocardial depressant effects, but that the changes in cardiac output reported in previous studies are secondary to changes in systemic vascular resistance.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oxigênio
/
Oxigenoterapia
/
Marca-Passo Artificial
/
Hemodinâmica
Tipo de estudo:
Clinical_trials
Limite:
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
Anaesthesia
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Reino Unido