ABSTRACT
We studied the effect of increasing alveolar volume on pulmonary carbon monoxide transfer (DLCO) and its components, i.e. membrane diffusing capacity (DM) and capillary blood volume (Qc), during mechanical ventilation in eight anaesthetized and paralysed healthy pigs (mean weight 11.2 kg). We used an inspiratory pause procedure for simulation of the single-breath technique, and inflated 15, 20, 25 and 30 ml kg-1 in random order. DM and Qc were derived using the Roughton-Forster equation. Per litre BTPS increase in effective VA, DLCO (inspiratory oxygen fraction 0.30) decreased on average by 11.8 mumol s-1 kPa-1, DM slightly increased by 2.7 mumol s-1 kPa-1 and Qc decreased by 241 ml. The increase in DM was much smaller than might be expected from the increase in VA, which we ascribe to a loss of the alveolar capillary membrane for gas transfer because of the concomitant decrease in Qc. The decrease in Qc may be explained by a squeezing effect of the intrapulmonary pressure rise on the alveolar wall and by stretching of lung tissue.
Subject(s)
Pulmonary Alveoli/physiology , Pulmonary Diffusing Capacity , Pulmonary Gas Exchange , Respiration, Artificial , Animals , Blood Volume , Capillaries , Carbon Monoxide , Lung Volume Measurements , Pulmonary Alveoli/blood supply , SwineABSTRACT
We studied the effect of forced inflation at different alveolar volumes (VA) on carbon monoxide diffusing capacity (DLCO) in anaesthetized, paralysed and mechanically ventilated healthy pigs. An inspiratory pause procedure (equivalent of the single-breath technique) consisting of a pause between an inflation and expiration, both at a constant flow rate, was used. The procedure was computer-controlled and could easily be standardized. In five pigs, VA was varied at constant inflation volume by increasing positive end-expiratory pressure (PEEP) from 2 to 10 cmH2O. Inspiratory pause time was varied from 1 to 8 s to verify whether the decay of CO was exponential. In nine pigs, DLCO was estimated at four different VA values by inflating with 15-30 ml kg-1 at 2 cmH2O PEEP. An exponential decay of CO was always obtained. With increasing VA by either an increase in PEEP or inflation volume, DLCO remained constant. Since the diffusing capacity of the pulmonary membrane is expected to increase with increasing VA, the constant DLCO may be attributed to a decrease in capillary blood volume.
Subject(s)
Carbon Monoxide/metabolism , Respiration, Artificial , Respiratory Mechanics/physiology , Animals , Blood Gas Analysis , Blood Pressure/physiology , Hemodynamics/physiology , Lung Volume Measurements , Positive-Pressure Respiration , Pulmonary Alveoli/metabolism , SwineABSTRACT
This study was initiated to obtain data on the rate of carbon monoxide (CO) uptake (theta CO) by hemoglobin in pig erythrocytes to derive, in a later study, the pulmonary capillary blood volume (Qc) in pigs from the Roughton-Forster relationship. Blood from five different female pigs was used. The theta CO, the milliliters of CO taken up by 1 ml of whole blood per minute per Torr CO tension, was determined on each blood sample with a continuous-flow rapid-mixing apparatus and double-beam spectrophotometry at 37 degrees C and pH 7.4 at four or five different PO2 values. Because the individual regression lines of theta CO vs. PO2 were not significantly different, a common regression equation was calculated: 1/theta CO = 0.0084 PO2 + 0.63. The slope of this regression line is significantly steeper than the reported slopes of regression lines for human and dog erythrocytes measured under the same conditions. Our results revealed that calculation of Qc in pigs by using theta CO values for human or dog erythrocytes would result in an underestimation of 51 and 50%, respectively.
Subject(s)
Carbon Monoxide/metabolism , Erythrocytes/metabolism , Hemoglobins/metabolism , Oxygen/blood , Animals , Blood Volume/physiology , Female , In Vitro Techniques , Kinetics , Regression Analysis , Species Specificity , SwineABSTRACT
To determine how much myocardial O2 consumption (VO2) would increase during an additional load on the heart in shunt as compared with control lambs, we studied 12 7-wk-old lambs with an aortopulmonary left-to-right shunt (59 +/- 3% of left ventricular output, mean +/- SE) and 11 control lambs during exercise at 80% of their predetermined peak VO2 (VO2peak), at 12 +/- 1 days after surgery. During exercise, systolic aortic pressure increased by 25% in the two groups. Left atrial pressure and left ventricular stroke volume did not change significantly and remained considerably higher in shunt than in control lambs. Heart rate, however, increased less in shunt than in control lambs (163 +/- 8 to 235 +/- 8 vs. 107 +/- 7 to 230 +/- 8 beats/min). The same was true for left ventricular myocardial blood flow (245 +/- 19 to 391 +/- 27 vs. 128 +/- 10 to 320 +/- 45 ml.min-1 x 100 g-1) and myocardial VO2 (847 +/- 101 to 1,692 +/- 136 vs. 528 +/- 58 to 1,579 +/- 178 mumol O2 x min-1 x 100 g-1). We conclude that, despite the volume load, myocardial VO2 of shunt lambs does not increase to a greater extent than in control lambs during a considerable additional load on the heart.
Subject(s)
Aorta/surgery , Coronary Circulation/physiology , Oxygen Consumption/physiology , Physical Exertion/physiology , Pulmonary Artery/surgery , Anastomosis, Surgical , Animals , Atrial Function, Left , Blood Pressure , Heart Rate , Sheep , Stroke Volume , Ventricular Function, LeftABSTRACT
A Dutch family is reported with congenital Horner's syndrome in five cases spanning five generations, with symptoms of varying degree but mainly ptosis and meiosis. Heterochromia iridium, anhidrosis, and enophthalmos were not present. The site of the lesion may be in the region between Gasser's ganglion and the short vertical segment of the internal carotid artery near the siphon. There are only four previous reports showing autosomal dominant inheritance of congenital Horner's syndrome.