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Biomedical subjects

P Elowsson

Publications and source records attributed to P Elowsson.

10 recordsLinked to original sources
PubMed2001

Continuous positive pressure ventilation during epidural blockade--effects on cardiac output distribution.

BACKGROUND: It has been shown that when cardiac output (CO) decreases during continuous positive pressure ventilation (CPPV), its regional distribution adapts with a favouring of vital organs. Does epidural blockade modify this adaptation? METHODS: Regional blood flows were assessed by the microsphere technique (15 microm) in 17 anaesthetised pigs during spontaneous breathing and CPPV with 8 cm H2O end-expiratory pressure (CPPV8) before and after epidural blockade. The block was induced at either the Th6-7 (Thep) or the L6-S1 (Lep) level with 1 ml of lidocaine 40 mg x ml(-1). RESULTS: When Lep was combined with CPPV8, mean arterial pressure and CO decreased significantly, and they decreased even more when combined with Thep. In contrast, the relative perfusion of the central nervous system, heart and kidneys remained stable during the four conditions studied. The adrenal perfusion during CPPV8 was obviated by epidural blockade. The absolute and relative perfusion of the skeletal muscle decreased during epidural blockade. The administered doses of epidural lidocaine did not affect blood flow in the spinal cord. CONCLUSIONS: The locally mediated nutritive vasoregulation of vital organs outweighed the sympathetic blockade induced by epidural blockade. During Thep blockade the animals were less capable of responding to the haemodynamic changes induced by CPPV8, probably due to the blockade of the cardiac part of the sympathetic nervous system.

Adrenal Glands↗
PubMed2000

Spread of epidural blockade in the anaesthetised pig using technetium99 and sensory-evoked potentials.

Our objective was to determine the extension and duration of a stable segmental thoracic or lumbar epidural blockade by lidocaine in the 20 to 25-kg pig. Fourteen anaesthetised pigs were investigated. The radioactive isotope technetium99 (Tc99) was added to lidocaine to evaluate the spread in the epidural space. One ml of this solution was administered via an epidural catheter either at the Th(6-7) or L6-S1 level. Sensory-evoked potentials (SEPs) were measured following peripheral nerve stimulation, to determine duration and sensory extension of the epidural blockade. The thoracic anatomical mean spread was 14.2 vertebrae. The end points of the spread were C3-C7 and Th8-Th13 and the lumbar anatomical mean spread was 10.2 vertebrae. The end points were Th10-Th12 and L6-S1. It was possible to abolish the SEPs with 2 and 4% lidocaine. A smaller volume of lidocaine was needed if a second dose was administered within 20 min. With 4% lidocaine it was possible to abolish the SEPs for more than 180 min. The use of 1 ml of 4% lidocaine repeated after 20 and 60 min at the Th(6-7) or L6-S1 level achieved a stable thoracic or lumbar epidural blockade.

Anesthesia, Epidural↗
PubMed1998

An evaluation of dual-energy X-Ray absorptiometry and underwater weighing to estimate body composition by means of carcass analysis in piglets.

To evaluate the use of dual-energy X-ray absorptiometry (DXA) and underwater weighing (UWW) for body-composition measurements, the carcasses of eight piglets (12-wk old, 15-22 kg in weight) were dissected into muscle, fat and bone. Thereafter, the components were homogenized and chemically analyzed for fat and bone mineral mass. Body components as measured by DXA correlated closely to the carcass analysis (r = 0.90-1.0). However, DXA still overestimated significantly the bone mineral mass, lean mass and total weight, and underestimated fat mass. The reproducibility of measurements, expressed as the CV for fat mass was 13.5%, whereas for total weight, lean mass and bone mineral mass, the CV was 0.74-1.9%. Fat mass was overestimated by UWW using the equations of Siri or Kraybill (r = 0. 77), but not by the equation of Lohman et al. (r = 0.69). The difference between the estimation of fat by chemical analysis and estimations by DXA and UWW was significantly affected by the amount of water in lean mass and fat-free mass.

Absorptiometry, Photon↗
PubMed1998

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil.

BACKGROUND: Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO). METHODS: General hemodynamics and regional blood flows assessed by microsphere technique (15 microns) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H2O end-expiratory pressure (CPPV8) before and after intravenous administration of propanolol (0.3 mg.kg-1 followed by 0.15 mg.kg-1.h-1, n = 8) or verapamil (0.1 mg.kg-1 followed by 0.3 mg.kg-1.h-1, n = 8). RESULTS: CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase. CONCLUSIONS: The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.

Adrenal Glands↗
PubMed1995

The use of intravenous nitroglycerin for emergency cervico-uterine relaxation.

A patient with a twin pregnancy was in preterm labour after 25 gestational weeks when, during vaginal delivery of the second twin, severe spasm of the cervix and fetal bradycardia ensued. Induction of general anesthesia did not relax the cervix. After bolus doses of nitroglycerin 100 + 50 micrograms i.v., prompt cervico-uterine relaxation was obtained allowing manual extraction of the baby. A short review of the literature and a summary of our experience in the administration of nitroglycerin i.v. in obstetrics are presented.

Adult↗