Biomedical subjects

R W Patterson

Publications and source records attributed to R W Patterson.

At least 19 recordsLinked to original sources

PubMed1989

Comparison of home occult blood tests and interaction of tests with ibuprofen.

The interaction of ibuprofen with home tests for occult blood was evaluated, and the accuracy of these tests was determined by validating the results with a specific quantitative assay of stool blood. Three home occult blood tests were evaluated: Early Detector, Fleet Detecatest, and CS-T Coloscreen Self Test. Fourteen men 19 to 35 years of age were instructed on how to use the tests and to record each day their dietary intake and stool consistency, the color of test control areas, the results, and the times of ibuprofen administration. The study consisted of a control period (days 0-5) and short-term (days 6-9) and long-term (days 10-14) ibuprofen periods. Each subject took two 200-mg tablets of ibuprofen three times daily beginning on day 6 and ending on day 14. During each study period, one stool sample was collected on each of three consecutive days. All three tests were performed on each sample, in addition to specific quantitative analysis with HemoQuant. All samples in the control period were negative for occult blood. Three positive results were reported by subject 4 in the short-term ibuprofen period, one with Fleet Detecatest and two with Early Detector. Subject 6 reported two positive Fleet Detecatest results and three positive Early Detector results during the long-term drug period. No positive results were detected with CS-T Coloscreen Self Test. The HemoQuant values showed that Early Detector produced one false-negative and two false-positive results.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Relationships among ventilation-perfusion distribution, multiple inert gas methodology and metabolic blood-gas tensions.

The retention equations upon which the Multiple Inert Gas Method is based are derived from basic principles using elementary algebra. It is shown that widely disparate distributions produce indistinguishable sets of retentions. The limits of resolution of perfused compartments in the VA/Q distribution obtainable by the use of the multiple inert gas method are explored mathematically, and determined to be at most shunt and two alveolar compartments ("tripartite" distribution). Every continuous distribution studied produced retentions indistinguishable from those of its unique "matching" tripartite distribution. When a distribution is minimally specified, it is unique. Any additional specification (increased resolution--more compartments) of the distribution results in the existence of an infinitude of possible distributions characterized by indistinguishable sets of retention values. No further increase in resolution results from the use of more tracers. When sets of retention values were extracted from published multiple inert gas method continuous distributions, and compared with the published "measured" retention sets, substantial differences were found. This illustrates the potential errors incurred in the practical, in vivo application of the multiple inert gas method. In preliminary studies, the tripartite distribution could be determined with at least comparable accuracy by blood-gas (oxygen, carbon dioxide) measurements.

Carbon Dioxide↗

PubMed1987

Derivation of VA/Q distribution from blood-gas tensions.

Gas exchange was modelled by a Fortran program. Arterial blood-gas tensions have higher resolution than inert gas retentions in terms of distinguishing a single VA/Q compartment from a progressively broadening lognormal distribution. The maximum number of compartments determinable by arterial blood-gas tensions is three; VA/Q distributions containing more compartments are non-unique. Without utilizing 100% inspired oxygen, arterial blood-gas tensions cannot resolve the relative perfusion in shunt and low-VA/Q compartments, but the total perfusion in these compartments is determinable. The way in which the arterial blood-gas tensions vary with the variables of two and three-compartment distributions is described. Two- and three-compartment VA/Q distributions are derivable from either arterial blood-gas tensions or inert gas retentions.

Algorithms↗

PubMed1981

Hypoxemia and pulmonary gas exchange during hemodialysis.

With measured values of arterial blood gas tensions, of expired respiratory gas fractions, and volume of the expired ventilation, the determinants of alveolar oxygen tension (PAO2) were used to evaluate their influence on the development of the arterial hypoxemia that occurs in spontaneously breathing patients undergoing hemodialysis using an acetate dialysate. Dialysis produced no significant changes in the alveolar-arterial O2 tension gradient (AaDO2). The extracorporeal dialyzer removed an average of 30 ml.m-2.min-1 of CO2. Accordingly the pulmonary gas exchange ratio (R) dropped from a mean predialysis value of 0.81 to 0.62 (P less than 0.001). The arterial CO2 tension remained constant throughout, whereas the minute ventilation, both total (P less than 0.01) and alveolar (P less than 0.01), decreased during dialysis. This decrease in ventilation accounts for more than 80% of the fall in PAO2. During dialysis there was a decrease (P less than 0.001) in arterial oxygen tension (PaO2), which varied among the individuals from 9 to 23% of control. During the postdialysis hour PaO2 returns to control values concomitant with increase in ventilation. The quantitative gas exchange relationships among R, alveolar ventilation, and AaDO2 predict the PaO2 values actually measured.

Adult↗

PubMed1979

Surgical intervention to relieve dystocia in a python.

The surgical procedure adopted to remove non-riable eggs from the oviduct of a python, Python anchitae, is described. Recovery was satisfactory, although it was not possible to establish whether reproduction was impaired. Reasons for the type of anaesthesia used and the choice of incision made are given.

Anesthesia, General↗

PubMed1978

Pulmonary shunting and lung volume during hypotension induced with trimetaphan.

In 10 dogs anaesthetized with pentobarbitone mean Pa02 decreased from the control value of 13.5 kPa to 10.2 kPa, cardiac output decreased by 33%, and right-to-left shunt doubled during hypotension induced with trimetaphan. There was no signficant change in functional residual capacity during the period of hypotension or recovery. The hypoxaemia resulted from an increase in ventilation/perfusion inequality, with a decrease in arterial saturation consequent upon a decrease in cardiac output with a constant shunt. During the recovery period, right-to-left shunting remained greater than the values obtained before induction of hypotension.

Animals↗

PubMed1978

Determinants of oxygen uptake during sodium bicarbonate infusion.

Steady-state passive hyperventilation alkalosis produces a predictable increase in oxygen uptake (VO2) proportional to the change in arterial pH (pHa) while variable changes in VO2 have been reported during alkali infusion. To compare metabolic with respiratory alkalosis 17 dogs were anesthetized with halothane and their VO2 response to respiratory alkalosis evaluated by hyperventilation. The pHa measured during this phase was duplicated during the later continuous infusion of NaHCO3 at which time either 1) ventilation was held constant at the control level, allowing arterial carbon dioxide tension (PaCO2) to rise as a consequence of the bicarbonate dissociation, or 2) PaCO2 was held constant by servo control of ventilation. Hyperventilation (pHa 7.6, PaCO2 13 Torr) produced an average increase in VO2 of 24%. During the bicarbonate infusion at constant ventilation (pHa 7.6, PaCO2 45 Torr) VO2 increased only 7%; however, when PACO2 was held constant by servo ventilation VO2 increased 21% above control. We conclude that respiratory and metabolic alkalosis produce similar increases in VO2 when steady-state acid-base conditions are achieved.

Alkalosis↗

PubMed1976

Acute clinical hypocalcemic myocardial depression during rapid blood transfusion and postoperative hemodialysis: a preventable complication.

Despite experimental evidence that myocardial depression resulting from rapid transfusion of ACD blood (citrate binds ionic calcium) is avoidable by simultaneous calcium administration, most hypovolemic patients receive calcium either after transfusion or not at all. Similar iatrogenic hypocalcemic myocardial depression occurs in normovolemic patients with known myocardial damage who are dialyzed for acute uremia when ACD blood prime is used at high initial flow rates (350 c.c. per minute) and when dialysis is performed against low calcium dialysate (2.5 mEq. per liter or less). This study tests the hypotheses that (1) rapid transfusion of as little as one unit of CPD blood causes a significant reduction in ionized calcium, (2) the depressive effect of CPD blood is significant and similar to that of ACD blood, (3) rapid blood transfusion (ACD or CPD) is safe if calcium is given simultaneously, (4) addition of calcium to the extracorporeal heparinized blood prime used in dialysis prevents initial depression, and (5) hemodynamic instability during dialysis is prevented when the dialysate is normocalcemic. From the results of our study, we made the following conclusions: (1) Ionized calcium is reduced significantly by rapid transfusion of CPD blood; (2) acute myocardial depression noted with CPD blood is similar to that previously observed with ACD blood and is prevented during transfusion of either type of blood by simultaneous calcium administration; and (3) hemodialysis in patients who have had cardiac surgery is safe if calcium is added to blood prime and dialysate is made normocalcemic.

Blood Preservation↗

PubMed1973