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Query: UMLS:C0278134 (anesthesia)
 110,339 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of phenobarbitone anesthesia on blood flow (CBF) and oxygen consumption (GMRO2) was evaluated in the rat brain, using a method that quantitatively measures CBF in mainly cortical areas. The data were compared to those obtained in animals under fentanyl citrate analgesia. Body temperature and arterial CO2 tension were maintained close to normal values in all groups. With 50 mg/kg of phenobarbitone, CBF and CMRO2 were reduced by about 20%. With 150 or 250 mg/kg, further reductions in CBF and CMRO2 were observed. At 250 mg/kg, CBF was reduced to one third, and CMRO2 to about 50% of normal. The results suggest that little further reduction in CBF or CMRO2 can be expected if the dose of phenobarbitone is increased above 250 mg/kg.
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PMID:The effect of phenobarbitone anaesthesia on blood flow and oxygen consumption in the rat brain. 106 78

Patients with neurological disorders may have a reduced ventilatory response to a rising PaCO2. This is often unpredictable and may become apparent only when other complications, e.g. infections (pneumonia), occur or when the patient is subjected to general anaesthesia. This paper described a simple method suitable for screening patients who may have an impaired capacity of eliminating CO2 when stressed. Ventilatory changes were determined during the continuous recording of the CO2 concentration in end-tidal air in 20 healthy subjects, who were breathing first air and then gas mixtures containing 21% O2 and 2.5 or 5% CO2. A prediction interval with 90 and 95% probability limits was constructed for healthy individuals. The normally expected change in minute ventilation per m2 body surface area per change in PACO2 (delta versicle E/m2, l/min/delta PACO2, for this technique is also given.
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PMID:A simple technique for the determination of the ventilatory response to rising arterial CO2 tensions, suitable for patients with neurological disorders. 106 79

Lung volumes, deadspace, ventilation, and ventilatory response to CO2 challenge were studied on the day before and for the first three days after corrective cardiac surgery. Ten patients underwent coronary artery bypass grafting and ten patients had mitral valve prostheses inserted. Half of the patients in each group received halothane as the major anesthetic, and the other half received morphine sulfate (1-2 mg/kg). Mitral valve-replacement patients anesthetized with morphine showed lower CO2 sensitivity on the first postoperative day than those who received halothane. Patients who had coronary artery bypass grafts tended to hyperventilate during the postoperative period, but this did not occur on the first postoperative day in those who received morphine anesthesia. Respiratory rate was always higher postoperatively, most markedly in patients who receivedhalothane for coronary artery bypass grafts. Vital capacity was diminished by 67 per cent in all groups postoperatively. VD/VT tended to increase during the first and second postoperative days and then decrease toward control values on the third postoperative day in all groups except valve-replacement patients who received morphine. Morphine anesthesia may increase the period of mechanical ventilation necessary after cardiac surgery partly as a result of impaired CO2 sensitivity.
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PMID:Postoperative respiratory effects of morphine and halothane anesthesia: a study in patients undergoing cardiac surgery. 108 25

In this review, an attempt has been made to select, evaluate, and interpret the pertinent literature relative to general anesthesia and the lung. Concepts of intrapulmonary gas exchange and respiratory system mechanics were synthesized, emphasizing the importance of changes in intrapulmonary gas distribution that are induced by general anesthesia and exploring the possible underlying mechanisms of these changes. The area of control mechanisms and the effects of anesthesia on respiratory regulation were not discussed, nor was the distribution of pulmonary blood flow examined. The following general conclusions can be reached: (1) impaired gas exchange occurs during general anesthesia, with both impaired oxygenation and CO2 elimination; (2) increased venous admixture and increased alveolar dead space impair gas exchange; (3) the distribution of ventilation is changed during general anesthesia, and this change is related to a decrease in FRC in the recumbent positions and to altered chest-wall mechanics. Numerous questions regarding the effect of anesthesia on the lung remain unanswered. The close relationship between advances in pulmonary physiology and the pulmonary effects of anesthetic actions is increasingly apparent, as is the importance of this knowledge in applying mechanical ventilation and end-expiratory pressure to patients with pulmonary disease.
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PMID:General anesthesia and the lung. 110 75

The influence of halothane, ether, carbon dioxide, and perfusion rewarming on the electrocardiogram was studied in 37 dogs subjected to surface-induced deep hypothermia. Significant anesthetic-related differences in P-R, QRS, Q-T and R-R intervals during cooling were not apparent; however, reduced arterial pressure, ventricular fibrillation, and a greater tendency for bradycardia requiring supportive measures were noted at low temperatures with halothane anesthesia. The use of 95% O2/5% CO2 significantly reduced the QTc at low temperatures; Other phenomena, including the occurrence and significance of J waves, are discussed. The relationship of the electrocardiogram to clinical and pathological results was evaluated and indicates that (1) properly managed resuscitation (manual massage and defibrillation) is not a serious hazard, (2) ether in 100% oxygen is the agent of choice for surface-induced deep hypothermia with prolonged circulatory arrest, and (3) halothane may be used in a procedure combining surface cooling and perfusion rewarming if given in a mixture of oxygen and carbon dioxide.
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PMID:Electrocardiographic changes during surface-induced deep hypothermia. The influence of ether, halothane, carbon dioxide, and perfusion rewarming. 112 62

Ventilation while breathing air and in response to hypoxia was studied in unanesthetized cats after carotid body chemo-defferentation. Hypoxic exposure (FIO2 equal to 0.07-0.12) of chemo-deafferented animals rapidly produced a high frequency, low tidal volume tachypnea. Tachypneic breathing, although usually associated with an increased expired ventilation, was accompanied by an increase in PACO2. In contrast to intact cats, behavioral arousal during hypoxic exposure was not observed after chemo-deafferentation. The response to milder hypoxia (FIO2 equal to 0.14-0.16) occurred with an increased latency, and there resulted a less marked depression of tidal volume and stimulation of respiratory frequency. Elevation of PACO2 to 5 mm Hg above the resting value, by addition of CO2 to the inspired gas, prevented the appearance of tachypnea upon subsequent reduction of FIO2 from 0.21 to 0.07. Depletion of central catecholamine stores, by administration of reserpine, did not prevent the tachypneic response to hypoxia. Following administration of anesthesia (pentobarbital, 30 mg/kg, IP), hypoxic exposure (FIO2 equal to 0.10) led to depression of both respiratory frequency and tidal volume, resulting in apnea within 1.5 minutes. It is concluded that hypoxia (FLO2 equal to 0.07-0.16) acts, in a concentration-related manner, as a powerful stimulant to central respiratory frequency generation and as a depressant of the tidal volume in the unanesthetized cat.
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PMID:Hypoxia-induced tachypnea in carotid-deafferented cats. 112 49

Althesin in dose ranges of 40, 60 and 80 mul/Kg was administered to six healthy unpremedicated volunteers according to a balanced incomplete block design. Both subjective and objective changes resulting from the administration of the agent were studied and analyzed. In the dose ranges used, Althesin was found to have no deleterious effects on heart rate, respiratory rate or blood pressure and apnoea only occurred in one patient who had an end-expiratory CO2 level lower than normal, due to preanaesthetic hyperventilation. The onset of sleep is prolonged with Althesin at the injection rate of 1 ml/10 secs. The onset of anaesthesia is not influenced by the total dose, but the sleep time is directly proportional to the dose injected. Auditory evoked responses tended to lie on a curve which might indicate that with increasing dose the time to reappearance of these responses is not correspondingly prolonged. However, this last observation must be confirmed by studies on a larger scale.
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PMID:Some pharmacological properties of althesin (CT1341) in man. 115 41

The CO2 surgical laser and microscope assembly have been used to excise carefully selected T1 carcinomas of the membranous portions of the cord. Healing has been prompt and return of function satisfactory. General anesthesia and suspension laryngoscopy have provided excellent definitions of the lesions; the laser has provided a precise method of dissection. Initial results have been excellent and long term results will depend on the accuracy with which the margins of the tumor are defined and the presence or absence of the tendency of the larynx to produce multicentric disease.
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PMID:Laser excision of carcinoma of the larynx. 116 Apr 59

The desirability of humidification of anesthesia systems for prolonged surgical procedures has been documented previously. Dry anesthetic gases damage the ciliated epithelium and cause respiratory heat loss. Chalon suggests that from 12 to 16 mg. of water/L. of gas is necessary to prevent damage to the tracheal epithelium. This study describes a method of obtaining values of from 21.5 plus or minus 0.4 to 39.3 plus or minus 0.1 mg. of water/L. by cycling the fresh gas flow through the carbon dioxide (CO2) absorber before exposure to the patient.
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PMID:Humidification of anesthetic systems for prolonged procedures. 116 61

Enflurane was administered as the primary anaesthetic agent to 200 children between the ages of 7 months and 14 years who were undergoing elective surgery. Induction and recovery were rapid and generally uneventful. Changes observed in the cardiovascular system included an initial fall in blood pressure, which tended subsequently to correct itself, and supraventricular arrhythmias mainly of nodal rhythm type. End expiratory CO2-concentration as measured by a capnograph tended to be elevated during spontaneous ventilation . Changes in liver function as measured by enzymatic activity were seen in some cases but were without statistical significance. Satisfactory muscle relaxation was generally obtained without the use of muscle relaxants. However, in two cases, poor relaxation occurred even at a concentration of 4.5% enflurane, and in these cases, EEG changes of polyspike suppression type were observed. This phenomenon is discussed in a subsequent article. As a result of their findings, the authors conclude that in paediatric anaesthesia enflurane is best suited for use in anaesthetics of relatively short duration with spontaneous respiration.
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PMID:A clinical trial of enflurane in children. 121 Oct 74


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