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Biomedical subjects

G C Carroll

Publications and source records attributed to G C Carroll.

At least 19 recordsLinked to original sources
PubMed1993

Comparison of responses to pituitary adenylate cyclase activating peptides 38 and 27 in the pulmonary vascular bed of the cat.

Responses to pituitary adenylate cyclase activating polypeptide (PACAP)-38 were investigated and compared with responses to PACAP-27 and vasoactive intestinal polypeptide (VIP) in the pulmonary vascular bed of the intact-chest cat under constant flow conditions. Under low resting tone baseline conditions, injections of PACAP-38 had little or no effect on lobar arterial pressure; however, when tone in the pulmonary vascular bed was raised to a high steady level (35-40 mm Hg) with U46619, intralobar injections of PACAP-38 caused dose-related decreases in lobar arterial pressure without altering left atrial pressure. The peptide induced biphasic changes in systemic arterial pressure. PACAP-38 was more potent than VIP in decreasing lobar arterial pressure, and both peptides were significantly less potent than PACAP-27 in dilating the pulmonary vascular bed. The present data show that PACAP-38 has significant vasodilator activity in the pulmonary vascular bed of the cat, and that the 27 amino acid form of the peptide is approximately 3-fold more potent than PACAP-38.

Animals↗
PubMed1992

Capnographic trend curve monitoring can detect 1-ml pulmonary emboli in humans.

To evaluate the potential of trend monitoring of end-tidal PCO2 (PETCO2) to detect pulmonary embolization, the capnograms of 24 mechanically ventilated patients were monitored during simulation of 1-ml pulmonary embolization by inflation of the balloons of their pulmonary artery catheters. Within 1 minute of balloon inflation, PETCO2 showed an exponential decrease to a new equilibrium. This response is characteristic of a CO2 wash-out curve produced by a step increase in dead space. Because of a steady baseline, the depression of the trend line during balloon inflation was apparent to a naive reader repeatedly in 20 of the 24 patients (sensitivity, 85%; specificity, 94%; positive predictive value, 98%; negative predictive value, 89%), despite a small mean decrease in PETCO2 (2 +/- 1.97 mm Hg). The PETCO2 trend curve did not reliably allow detection of balloon inflation in 4 patients whose capnograms were poorly formed. In conclusion, during constant ventilation, PETCO2 trend curve monitoring might provide clinically useful "on line" information regarding pulmonary embolization.

Carbon Dioxide↗
PubMed1990

Fourth-order blood pressure waves.

A critically ill 80-year-old man had blood pressure waves with a period of about 30 minutes. These blood pressure oscillations, lasting longer than 18 hours, were accompanied by oscillations in heart rate, central venous pressure, pulmonary arterial pressure, and oxygen saturation of mixed venous blood. No discernible variations in external conditions caused the oscillations. Oscillations with such long periods heretofore have not been reported.

Aged↗
PubMed1990

Effect of alkalinization and fluids on survival in acute, non-hypoxic respiratory acidosis.

Effects of intravenous normal saline, sodium bicarbonate, hypertonic saline, and Tromethamine were studied in 21 pigs and 60 rats subjected to acute, severe respiratory acidosis. Transient multiphasic alterations of systemic arterial pressures were seen with boluses of each agent-especially sodium bicarbonate and hypertonic saline-but any improvements in hemodynamic variables were transient. At the dose given, sodium bicarbonate significantly increased PaCO2 while decreasing hydrogen ion (H+) accumulation, whereas tromethamine buffered pH without significantly increasing PaCO2. However, no change of either arterial or venous H+ or PCO2 could be identified which rapidly produced death. Survival times were statistically equivalent among all groups. Therefore, intravenous treatment of respiratory acidosis with fluids or alkalinizing agents appears neither helpful nor harmful.

Acid-Base Equilibrium↗
PubMed1988

Minimal positive end-expiratory pressure (PEEP) may be "best PEEP".

In the absence of clinical trials, positive end-expired pressure (PEEP) has been accepted as efficacious for treatment of postoperative decreases in arterial oxygen tension (PaO2) from a variety of causes including adult respiratory distress syndrome (ARDS). PEEP is thought to increase PaO2 by alveolar recruitment, which in turn, has been hypothesized to play a decisive role in pulmonary recovery. One hundred and eighteen patients were followed prospectively, and after development of decreased PaO2, randomized to receive recruitive PEEP (determined by blood gas criteria) or supportive PEEP (the minimal PEEP required to maintain PaO2 above 60 mm Hg on .5 inspired O2 fraction (FIO2). No prognostic factors were significantly different between the two groups. Recruitive PEEP application in 22 patients yielded a significantly increased incidence of hypotension (55 percent), pneumothorax (20 percent), and death during treatment (27 percent) when compared to the 28 supportive PEEP patients who had no hypotension or pneumothorax and only one death during treatment (4 percent). After PEEP treatment, deaths in each group were similar (19 percent and 15 percent, respectively). We find no evidence that PEEP treatment promotes beneficial outcomes and conclude that recruitment attempts may be harmful.

Humans↗
PubMed1988

Blood pressure monitoring.

This article reviews several methods for the measurement and monitoring of systemic arterial blood pressure. Principles of operation of noninvasive and invasive devices are described. Techniques for insertion and maintenance of arterial catheters are discussed. Finally, complications and other problems of both noninvasive and invasive methods are presented.

Adult↗
PubMed1987

A continuous monitoring technique for management of acute pulmonary failure.

Continuous monitoring of mixed venous oxygen saturation (SvO2) and arterial oxygen saturation (SaO2) was used to guide cardiovascular and pulmonary physiologic manipulations in three patients. An index, termed the "shunt index" (SI), of venoarterial admixture (Qva/Qt) was calculated at the bedside. SI correlated significantly in each patient with Qva/Qt (p less than .01). In one of the patients, continuous end-tidal CO2(ETCO2) was also monitored, allowing rapid titrations of ventilator settings and cardiovascular support free from the need to sample arterial and mixed venous blood to assess the effect of each intervention.

Aged↗
PubMed1983

Effect of bacteremia and fluid resuscitation on cardiac output.

The cardiac output acutely inducible by a 1-ml/kg/min saline infusion was observed in 12 septic and 7 nonseptic cynomolgus monkeys. In septic monkeys intravenous live E. coli were titrated to rapidly produce equivalent hypotension which was maintained for 1 hr before saline. Bacteria dose range was 1.3 X 10(11) bacteria/kg-400 X 10(11) bacteria/kg. There was no significant correlation between the dose of bacteria and the cardiac output nadir; however, the subsequent maximum cardiac output during saline resuscitation was significantly negatively correlated with the bacterial dose. In conclusion, widely varying amounts of intravenous bacteria can produce the same degree of hypotension and not correlate with cardiac output. In contrast, cardiac output measured early during subsequent saline resuscitation better predicts the severity of bacteremia.

Animals↗
PubMed1982

Hyperdynamic severe intravascular sepsis depends on fluid administration in cynomolgus monkey.

A new model of high cardiac output septic shock in primates is presented that includes hemodynamic and metabolic effects of separate and combined infusions of normal saline and live Escherichia coli. In monkeys receiving ketamine anesthesia, cardiac output (QT) increased with saline loading but not significantly with bacterial infusion, and bacterial infusion without saline never significantly increased QT. Depressed oxygen consumption (VO2) was reversed with saline loading. In spite of continuing E. coli infusion, radiolabeled microspheres showed no increase in systemic anatomic shunt when QT was elevated. It is perceived that the tissue dysfunction associated with sepsis, which is called septic shock, and elevation of cardiac output are related only indirectly. High cardiac output only reflects an adequate volume status in a stressed individual; some of the afferent stress signals can be related to the septic state, but no specific or direct relationship is involved. In general, shock as indicated by a depression of VO2 does not appear to occur when QT is increased.

Animals↗
PubMed1980

Dental flossing and its relationship to transient bacteremia.

This study was designed to determine the role of dental flossing in producing transient bacteremias. An improved protocol that provides for repeated samplings of blood was developed. Four patients had 32 blood cultures taken (16 before flossing and 16 after). Two of the patients had no periodontal disease and two had only marginal gingivitis. The results showed that the patients who flossed daily developed no bacteremias but that patients who delayed flossing from 1 to 4 days developed bacteremias 86% of the time. It is important that patients who have a history of rheumatic fever and those who have internal prosthetic devices be cautioned regarding sporadic flossing. While gingival bleeding was not significantly related to bacteremias in this study, further investigation is needed to ascertain how flossing in various types of periodontal disease relates to bacteremias.

Adult↗
PubMed1968

Fine-structural correlates of growth in hyphae of Ascodesmis sphaerospora.

Mycelial mats of Ascodesmis sphaerospora were fixed and embedded for electron microscopy, and thin sections of 1-mm blocks, taken from the 1st to the 7th mm behind the hyphal tips, were cut parallel to the long axis of the hyphae. The hyphal tip region is characterized by an outer zone of electron-transparent vesicles, 500 to 1,000 A in diameter, and is apparently associated with wall elaboration. Immediately behind this region, dense granules become evident along convoluted membrane systems and along the plasma membrane; in the same region are numerous small lomasomes in the lateral wall. As the hypha grows, septa are laid down at 3- to 7-min intervals at a distance of 200 to 250 mu behind the hyphal tip. A cylinder of endoplasmic reticulum is intimately involved in cross-wall deposition from its earliest stages; as the wall grows in, it becomes increasingly constricted in the pore region, finally assuming a torus-like configuration. Woronin bodies are shown to have a crystalline substructure and to originate in pouch-like membrane systems. Cross-walls from a 7- to 13-hr-old mycelium frequently show highly ordered structures in the vicinity of the pore. These structures may appear either as laminar stacks of discs to one side of the pore or as series of stubby concentric rings within the pore area itself. In the latter case, a mass of granular material is frequently seen plugging the pore. Other unusual organelles and inclusions in 7- to 13-hr hyphae are vesicles containing swirls of beaded or dilated membrane, membrane-enclosed rods, and stacks of unit membranes associated with spherical, electron-transparent vesicles.

Ascomycota↗