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NEUROHUMORAL CONTROL OF CARDIOVASCULAR FUNCTION
Departments of 1Obstetrics, 2Cardio-Thoracic Surgery, 3Anesthesiology, 4Neonatology, 5EA 1049, Department of Biophysics, and 6Departement Hospitalo-Universitaire de Recherche Experimentale, Centre Hospitalier Régional Universitaire de Lille, Lille, France
Submitted 29 June 2004 ; accepted in final form 13 October 2004
The fetus is able to exhibit a stress response to painful events, and stress hormones have been shown to modulate pulmonary vascular tone. At birth, the increased level of stress hormones plays a significant role in the adaptation to postnatal life. We therefore hypothesized that pain may alter pulmonary circulation in the perinatal period. The hemodynamic response to subcutaneous injection of formalin, which is used in experimental studies as nociceptive stimulus, was evaluated in chronically prepared, fetal lambs. Fetal lambs were operated on at 128 days gestation. Catheters were placed into the ascending aorta, superior vena cava, and main pulmonary artery. An ultrasonic flow transducer was placed around the left pulmonary artery. Three subcutaneous catheters were placed in the lambs' limb. The hemodynamic responses to subcutaneous injection of formalin, to formalin after fetal analgesia by sufentanil, and to sufentanil alone were recorded. Cortisol and catecholamine concentrations were also measured. Pulmonary vascular resistances (PVR) increased by 42% (P < 0.0001) after formalin injection. Cortisol increased by 54% (P = 0.05). During sufentanil infusion, PVR did not change significantly after formalin. Cortisol increased by 56% (P < 0.05). PVR did not change during sufentanil infusion. Norepinephrine levels did not change during any of the protocols. Our results indicate that nociceptive stimuli may increase the pulmonary vascular tone. This response is not mediated by an increase in circulating catecholamine levels. Analgesia prevents this effect. We speculate that this pulmonary vascular response to nociceptive stimulation may explain some hypoxemic events observed in newborn infants during painful intensive care procedures.
experimental pain animal model; fetal pain; fetal analgesia; pulmonary vascular reactivity; stress hormones
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V. H. Debarge, B. Sicot, S. Jaillard, I. Gueorgiva, A. Delelis, P. Deruelle, A. S. Ducloy, and L. Storme The Mechanisms of Pain-Induced Pulmonary Vasoconstriction: An Experimental Study in Fetal Lambs Anesth. Analg., April 1, 2007; 104(4): 799 - 806. [Abstract] [Full Text] [PDF] |
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