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Biomedical subjects

J Qvist

Publications and source records attributed to J Qvist.

88 records · Page 5Linked to original sources
PubMed1979

Regional blood flow during simulated diving in the conscious Weddell seal.

Changes in regional blood flow during simulated normobaric diving were studied in the conscious Antarctic Weddell seal (Leptonychotes weddelli) by injecting 25-microns radioactive microspheres into the left ventricle. Injections were performed before and 8--12 min after submersion of the head in iced seawater. Diving was associated with a fall in cardiac output from a mean control value of 39.8 +/- 10.2 to 5.6 +/- 3.4 l/min (mean +/- SD) and in heart rate from 52 +/- 15 to 15 +/- 4 beats/min. Blood flow to the splanchnic and peripheral vascular bed was reduced by more than 90%, cerebral blood flow was unchanged, right and left ventricular blood flow decreased by 85%, and adrenal blood flow decreased by 39%. The pulmonary fraction of the injected microsphere dose increased from 7.9 to 29.9% during diving. This may signify a large increase of peripheral arteriovenous shunting during the dive and/or increased bronchial artery blood flow. It is concluded that blood flow during diving is directed to organs and tissues according to their metabolic requirements.

Animals↗
PubMed1979

Recruiting collapsed lung through collateral channels with positive end-expiratory pressure.

We studied reinflation of collapsed parts in excised normal human lungs through both the ordinary bronchial route and through collateral channels. A model of atelectasis was made either by simple collapse or by applying a positive pressure to the pleura and a negative to the airway. Five different ventilatory patterns were used for reinflation: simulated normal breathing with and without continuous positive airway pressure (CPAP), simulated deep breathing and mechanical ventilation with and without positive end-expiratory pressure (PEEP). All methods, except normal breathing without CPAP, reinflated the collapsed part with pressures well within the range used clinically. The most effective way of re-expanding collapsed lung was the application of CPAP during simulated normal breathing or PEEP during mechanical ventilation, which required smaller transpulmonary pressure swings than the other methods. A comparison between CPAP and PEEP showed CPAP to be preferable. Collateral reinflation occurred just as readily as normal reinflation and the results suggest that collateral reinflation is the primary choice. This route of reexpansion also has a potential secretion clearing effect in that pressure is built up distal to an obstruction.

Adult↗
PubMed1977

Pulmonary metabolism during diving: conditioning blood for the brain.

During experimental diving by the awake Weddell seal, blood glucose concentration falls consistently. A large fraction of the glucose consumed from the central circulating blood appears as lactate. During diving, the lung utilizes blood lactate in preference to blood glucose as a source of both carbon and energy, and it is able to release glucose into pulmonary venous blood to supplement the supply available for brain metabolism.

Animals↗
PubMed1977

Marginal leakage along Concise in relation to filling procedure.

Bacteria beneath 58 class V Concise restorations on permanent molars in vivo were registered. After an observation period of 1-4 months bacteria were found in all 13 cavities filled with Concise only, in 14 out of 15 cavities filled with resin and Concise, in 12 out of 15 acid-etched cavities with Concise only and in 8 out of 15 acid-etched cavities filled with resin and Concise. Only the difference between the two procedures: Concise only and acid + resin + Concise, was significant. The occurrence of bacteria in the dentinal tubules beneath the cavities was greatest when the cavities had been etched.

Acid Etching, Dental↗
PubMed1977

Bacteria in cavities beneath intermediary base materials.

The ability of six different intermediary base materials to prevent bacterial entrance beneath silicate cement fillings was investigated in vivo in primary molars. After an observation period of 1 month, bacteria were found on the pulpal wall in two out of 10 cavities beneath Fluoritec and four out of 10 cavities beneath Durelon solid mixed, De Trey phosphate cement solid or creamy mixed. Beneath the intermediary base materials Dycal, zinc oxide-eugenol cement, Dropsin and Durelon creamy mixed, no bacteria were found. In cavities filled with silicate cement or silver amalgam only, bacteria were observed in nine out of 10 and in five out of 10 cavities, respectively.

Bacteria↗
PubMed1977

Microstructure of inner surfaces on composite restorations related to filling procedure.

The inner surfaces of 40 Concise restorations placed in vivo on permanent molars have been studied by scanning electron microscopy. Only grinding traces could be seen on fillings from cavities which had not been etched, while the morphologic structure of the enamel and dentin was reflected on fillings from acid-etched cavities. Application of low-viscous non-composite resin in the cavities before filling with the composite resin did not influence the enamel pattern on the fillings, while the amount of processes of resin corresponding to the dentinal tubules in etched cavities was significantly increased. In the discussion the difference in surface structure of the fillings is correlated to marginal leakage along similar restorations.

Acid Etching, Dental↗
PubMed1977

pH and haemoglobin oxygen affinity in blood from the Antarctic cod Dissostichus mawsoni.

Blood pH in the antarctic cod (Dissostichus mawsoni) and in two Trematomus species, occlrring at --1-9 degrees C, is extremely high (approximately 8-2 to 8-3). This supports and extends Rahn's (1966) model for the temperature-pH relationship in cold-blooded vertebrates. The blood of D. mawsoni shows a low oxygen affinity (P50 approximately equal to 14-5 mmHg at pH 8-16 and -1-9 degrees C). Despite normal in vitro temperature and pH sensitivities, blood P50 increases only slightly when live fish are temperature-stressed (+ 4-0 degrees C), or become acidotic as a result of agitational stress (blood pH 7-71), primarily as a result of compensatory decreases in blood ATP levels. Oxygen-binding properties of 'stripped' (cofactor-free) solutions of D. mawsoni haemoglobin were measured in attempts to elucidate the molecular mechanisms involved in the function of the pigment.

Adenosine Triphosphate↗
PubMed1975

Hemodynamic responses to mechanical ventilation with PEEP: the effect of hypervolemia.

The hemodynamic effects of prolonged mechanical ventilation with positive end-expiratory pressure (PEEP), with and without blood volume augmentation, were studied in 18 beagles anesthetized with halothane (0.7 per cent end-tidal). Addition of 12 cm H2O PEEP during mechanical ventilation in normavolemic dogs was associated with reductions of transmural cardiac filling pressures, cardiac index and stroke index to 50 per cent of control values. Circulatory adaptation did not occur. Filling pressures and flow remained unchanged during the ensuing 8 hours when PEEP was maintained. They returned to control levels when PEEP was discontinued, except for the transmural right ventricular end-diastolic pressure, which remained elevated above control levels. Systemic vascular resistance was unchanged, but pulmonary vascular resistance doubled upon addition of PEEP. Following autologous whole blood transfusion (25 ml/kg) during mechanical ventilation with PEEP, cardiac index returned to, and remained at, control levels. After PEEP was discontinued, cardiac index increased acutely and remained elevated for the remainder of the study period (as long as 7 hours). Comparable transfusion during mechanical ventilation without PEEP elevated cardiac index only transiently. Right atrial, pulmonary capillary wedge, and right and left ventricular end-diastolic pressures showed marked increases relative to atmospheric with PEEP and after transfusion. Calculated transmural pressures demonstrated clear reductions with application of PEEP, followed by increases to control levels with transfusion and further increases to above control when PEEP was discontinued. Study of ventricular function curves revealed that changes in filling pressures and not to changes in ventricular contractility. Transmural pulmonary arterial diastolic pressure rose throughout the 12 hours of study, despite return of pulmonary vascular resistance to control level with removal of PEEP. Thus, acute decreases in cardiac filling pressure, cardiac index, and stroke index persist consequent to application of PEEP, and circulatory adaptation does not occur. The apparent hemodynamic deterioration may be reversed by blood volume augmentation, but when PEEP is discontinued, hypervolemia with consequent increases in filling pressures and a move along a ventricular function curve will occur. Changes in cardiac index will depend upon the overall state of right and left ventricular contractility.

Animals↗
PubMed1975

Extracorporeal perfusion for acute respiratory failure: recent experience with the spiral coil membrane lung.

Selection criteria, clinical data, and physiological measurements obtained during five extracorporeal membrane lung perfusions for acute respiratory insufficiency are presented. Four patients died and 1 survived. A new technique of femoral artery cannulation to allow aortic arch perfusion is described. When properly monitored, this route provides improved oxygen delivery to the brain during venoarterial (VA) perfusion. The importance of monitoring the equivalent of carotid artery Po2 during VA perfusion is emphasized. Recognition of the effects of high cardiac output in limiting the quality of extracorporeal perfusion, plus the use of hypothermia to reduce output, are stressed. We have confirmed that perfusion can be accomplished with small quantities of heparin, so that bleeding is reduced, but thrombocytopenia and occasional hemorrhage continue to be persistent problems.

Acute Disease↗
PubMedDate not supplied

Daily diving pattern of Korean and Japanese breath-hold divers (ama).

Daily diving patterns and thoracic skin and sea-water temperatures were recorded during the entire work shift of Korean female unassisted (cachido) and Japanese male unassisted and partly assisted (funado) divers using Underwater Physiological Data Loggers developed in Buffalo and Japan. All 3 groups of divers were studied during the summer of 1989 and 1990. Additional studies were conducted during the winter of 1991 on Korean female divers who, unlike Japanese divers, dive all year round. The water temperature of the diving grounds in summer was 24 degrees C in both Korea and Japan, and 10 degrees C during winter in Korea. Both Korean female and Japanese male cachido divers made 113-138 dives a day and stayed in the water a total of 170-200 min.day-1, of which only 52-63 min were spent diving submerged, and the remaining time at the water surface. These diving patterns were not different between female and male cachido divers. Compared with Japanese male divers, Korean female divers dived to a shallower depth (3.7 vs. 6.9 m) with shorter dive time (29 vs. 37 s) and shorter bottom time (14 vs. 18 s). Velocities of descent (0.72 vs. 0.47 m.s-1) and ascent (0.77 vs. 0.56 m.s-1) were also slower in female divers than in male divers. The diving pattern of Korean female divers was similar in both summer and winter. Although all cachido divers wore wet suits and thus were protected from severe cold stress, thoracic skin temperature decreased during a work shift by 7 degrees C in winter (vs. 1 degree C in summer) in Korean divers. Compared with Japanese male cachido divers, Japanese male funado divers stayed in the diving ground (including time in the boat) longer (201 vs. 305 min.day-1) but performed only 23 dives per day. The average diving depth (9.7 m), duration (69 s), and bottom time for each dive (45 s), however, were significantly greater in funados. The velocity of vertical descent (1.0 m.s-1) was also significantly greater in funados because they descend with a weight (8-12 kg). The rate of ascent was not different.

Body Temperature↗