ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

That anesthesia may alter hemoglobin oxygen affinity was tested in 19 groups of six to eight individuals. Paired venous and arterial blood samples were analyzed for oxyhemoglobin content, pH, base excess and Po2Venous oxygen tension was calculated from the standard dissociation curve, allowing for body temperature. In conscious man this calculated Po2agreed well with the directly-measured Po2. During general anesthesia, however, there was usually a positive difference of measured Po2minus calculated Po2unrelated to agent, duration, or depth of anesthesia. The shift in dissociation ranged from less than one torr in a group inhaling dicthyl ether to 12 torr during Ethrane anesthesia, with intermediate values in other groups and with other agents. The average direction and degree of the shift were sufficient to compensate for a Bohr effect on hemoglobin dissociation resulting from a pH of 7.6.

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

The reserve power of myocardial muscle depressed by Ethrane was determined by means of changes in time interval of stimulation in seven isolated cat papillary muscles. Ethrane (average concentration of 6.5 ± 0.1 mg/100 ml) decreaesd maximal isometric forces to 56 per cent of the control value at the “rested-state contraction” (RSC). Ethrane also decreased maximal isometric force (Fm) and rate of force development (dF/dt) at any given time interval of stimulation. Slopes of both time interval-force and time intcrval-dF/dt curves were unaffected by Ethrane. The percentage depressions in Fmand dF/dt were reduced from 44 and 37 to 25 and 21 per cent by decreasing the time interval from 240 sec to 3.2 sec. The ability of heart muscle to respond to changes in time interval of stimulation was, therefore, maintained during administration of Ethrane. Possible mechanisms of myocardial depression induced by Ethrane are discussed.

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Possible activation of a volume receptor mechanism was studied using intermittent positive-pressure breathing (IPPB) with an end-expiratory airway pressure of zero. Urine formation, plasma antidiuretic hormone (ADH) levels, respiratory airway mechanics, cardiac output and cardiovascular function were measured during spontaneous ventilation and IPPB in dogs anesthetized with chloralose. Minimal changes in respiratory mechanics and cardiovascular function were observed. However, in all instances, urinary output increased and plasma levels of ADH decreased during mechanical ventilation. Upon resumption of spontaneous respiration, urinary output and plasma ADH returned toward control levels. Therefore, IPPB is not the direct cause of water retention through the activation of a volume receptor mechanism and the release of antidiuretic hormone.

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Two cases in which the Interaction between magnesium and neuromuscular blocking agents proved hazardous are reported. The nature of the interaction was investigated in the rat phrenic nerve-diaphragm preparation. Magnesium potentiated the neuromuscular blocks produced by d-tubocurarine, decamethonium and succinylcholine. Proposed mechanisms of interaction as well as clinical implications arc discussed.

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Using the anesthetic requirement for halothane (MAC) to follow central nervous system depression in dogs, acute hypoxia reduced MAC starting at Pao238 mm Hg. The decrease in MAC related to both arterial oxygen content (Cao2) and arterial pH (group 1). Therefore, acute hypoxia to Pao230 mm Hg was induced in two groups of dogs during hypocapnia (group 2) and normocapnia (group 3). MAC decreased far more rapidly during normocapnic hypoxia than during hypocapnic hypoxia. Respiratory alkalosis maintained pH at 7.39 in group 2, and Cao2remained at 10 vol per cent In group 3, arterial pH fell progressively, reducing Cao2to 7.4 vol per cent at a constant Pao2of 30 mm Hg. Significant regression lines correlated arterial and mixed venous oxygen contents, arterial oxygen transport, and arterial pH with the decreases in MAC in groups 2 and 3. Serial CSF pH determinations in both groups correlated poorly with the reductions in MAC.

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Cerebral extracellular fluid (ECF) Po2, Pco2and pH were measured with cortical surface electrodes and HCO3-was calculated during acute hypoxia (Pao225–30 mm Hg). The values found did not correlate consistently with reduction of halothane requirement (MAC). In the first half hour of either nonnocapnic or hypocapnic hypoxia, MAC decreased to 76 per cent of control, unrelated to the ECF measurements. In the remaining hour and a half of normocapnic hypoxia (group 1), MAC decreased to 19 per cent of control while cerebral ECF pH fell to 6.93. Arterial oxygen content (Cao2) decreased as arterial pH fell. During the remaining hour and a half of hypocapnic hypoxia (group 2), MAC and Cao2remained constant while ECF pH decreased to 7.23. Hypoxia affected the Po2and HCO2-of ECF similarly in the two groups. Wide scatter of the data prevented meaningful correlation of MAC and cerebral ECF Po2, pH, and HCO2-in both groups. Cerebral ECF pH was not representative of cistemal CSF pH during hypoxia, as evidenced by a rapid and profound decrease in ECF pH while CSF pH remained fairly constant. The surface electrodes gave a closer measure of cerebral acid-base function than cistemal CSF. However, surface changes may reflect brain intra-cellular fluid acid-base function poorly, especially during periods of rapid change.

ISSN:0003-3022    

出版商:OVID    

年代:1970

数据来源: OVID