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

The effects of positive end-expiratory pressure (PEEP) at 5, 10, 15, and 20 cm H2O on the distribution of ventilation-perfusion (VA/Q) ratios was determined in four normal dogs and in ten with oleic acid-induced acute hemorrhagic pulmonary edema. Tidal volume and frequency were held constant at all times with mechanical ventilation during intravenous pentobarbital and gallamine anesthesia. Normal dogs had little or no shunt, and no areas of low (less than 0.1) or high VA/Q (greater than 10.0) at zero end-expiratory pressure (intermittent positive-pressure breathing). In these animals increasing PEEP caused progressive depression of cardiac output, associated with an increase in ventilation to both high VA/Q and unperfused regions. PEEP greater than or equal to 10 cm H2O resulted in a reduction in Pao2 and an increase in PaCO2. In dogs with pulmonary edema, PEEP's of 5 and 10 cm H2O resulted in dramatic reductions in shunt, virtual obliteration of low VA/Q regions, and market improvement in Pao2. However, at 15 and 20 cm H2O PEEP's high VA/Q and dead space ventilation with CO2 retention again developed in all but the most severely affected (shunt greater than 40%) dogs.
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PMID:Effects of positive end-expiratory pressure on gas exchange in dogs with normal and edematous lungs. 33 16

Closed system anesthesia is economical, minimally, polluting, and conserves a patient's airway heat and moisture. Yet this method of anesthesia is not widely used because it is considered dangerous by many clinicians. We review the origins of that belief and then test the application of 2 schemes for administering potent agents in a closed system with CO2 absorption. We 1st employed Lowe's square-root-of-time uptake model in 30 patients, using halothane or enflurane. We found that the model provided a good starting point for learning to use the closed system. However, anesthetic concentrations were not accurately predicted. Based on our experience with that model, we examined a simpler approach. We began each of 10 anesthetics using a semiclosed system, then closed the system. Only sufficient O2 for metabolic demand and halothane were added to the closed system. The rate of halothane administration was the same for each patient. This approach proved clinically satisfactory, and the measured halothane concentration remained relatively constant during 45 minutes using the closed system. Changing from a semiclosed to a closed system affords the advantages of the closed system 75 percent of the time, yet requires no extra tasks or equipment.
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PMID:A compromise for closed system anesthesia. 34 45

One hundred and forty-one patients for general and urological surgery were anaesthetized by epidural anesthesia (PDA) using bupivacaine-CO2 0.5% solutions. A frequency peak for the initial dose between 21-23 ml was noted. The response time and latency period were found to be 2.99 +/- 1.40 min and 11.02 +/- 3.66 min (smallest time unit 0.5 min). The effective duration was 5.02 +/- 0.93 h. The sensory spread reached on average to T 6.06 +/- 1.41 segments for the patients with typical injection locations at L2/3-L4/5. A mean dose of 6.25 +/- 0.18 mg per spinal segment was used. Side effects were not seen apart from occasional hypotension. The failures were not related to the anesthetic drug. The degree of muscle relaxation was for the majority of cases evaluated at 2 +, which was sufficient for the abdominal operations. The results are compared with the data obtained using bupivacaine-HC1; the advantages of bupivacaine-CO2 are described.
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PMID:[Clinical trial of bupivacaine-CO2 (author's transl)]. 35 87

Six normal weight subjects without any heredity of diabetes (group 1), 3 obese subjects with normal (group 2) and 9 with pathological carbohydrate tolerance (group 3) were characterized by a 2-h glucose infusion test. Adipose tissue fragments were obtained from the abdominal wall by surgical biopsy under intracutaneous anesthesia. Adipocytes were isolated by collagenase digestion and incubated in buffer containing [1-14C] glucose and different concentrations of insulin. The metabolic effect of insulin was expressed as percent increase above control 14CO2 production. Maximal CO2 raised to 207 +/- 25% and 154 +/- 9% in groups 1 and 2, respectively. These values were significantly higher than in obese subjects displaying a pathological carbohydrate tolerance (group 3; 119 +/- 6%). A negative correlation was found between blood glucose levels and biological activity of insulin on adipocytes. The results suggest that insulin sensitivity of target tissue seems to play an important role in development of carbohydrate intolerance.
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PMID:Relationship between carbohydrate tolerance, insulin secretion, and insulin sensitivity of isolated fat cells from obese protodiabetics. 36 Jul 50

It is generally accepted, that the progress in surgical treatment of congenital malformation is closely related to the progress in highly-specialised methods of newborn anaesthesia. The safe methods of anaesthesia have to be adapted to anatomical and physiological peculiarities of the earliest days of life as well as to different reaction to drugs and anaesthetics. The preoperative preparation in newborns used to be often very short, because most of the problems of the neonatal period are emergency surgical interventions and there is no time for treatment even of the serious disturbances of basic physiological functions. The purpose of this study was to estimate methods of general anaesthesia in newborns, which have been introduced in the Anaesthesiology Department of the National Research Institute of Mother and Child. The main element of these methods was general anaesthesia with muscle relaxants and controlled ventilation as a routine. The estimation was based on general analysis of 10 years practice when these methods of anaesthesia were used. During this time 515 anaesthesias to 408 both-sex newborns were given (Tab. I, Fig. 1). 85% of anaesthetized newborns were operated because of congenital malformations (Tab. I); 46% of operations were performed during their first week of life, 21% were operated in first 24 hours of life, mostly as an emergency (Fig. 3). 10% of operations were performed is prematures (body weight below 2500 g) (Fig. 4). The "routine" anaesthesia was given in 82% cases. Awake intubation in unpremedicated newborns was performed. Anaesthesia was maintained with nitrous oxide-oxygen mixture (1:1 or 2:1). D-tubocurarine in 95% of cases was used. The initial dose 0,5 with matures and 0,25 mg with premature babies was used. If necessary supplementary doses were given. During anaesthesia, intermittent positive pressure ventilation (IPPV) with frequency at least 60/min. was used. During this ventilation, hyperventilation and positive end-expiratory pressure (PEEP) were obtained. Precordial stetoscope and thermometer probe was used as a routine. In some special cases eCG, end-expired CO2 (capnography), pletysmography were also recorded; blood gas analyses were checked. All intra- and postoperative complications as well as postoperative mortality have been analysed in details. During 3,3% of operations some complications had been observed. The total incidence of early psotoeprative complications was 20%. In this group the most frequent were respiratory complications (16,1%). Serious disturbances in pulmonary gas exchange during operation and early postoperative period were not found.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[General anesthesia in infants]. 40 Jul 70

A comparison was made between the effects of two different anesthetics, alpha-D-gluco-chloralose and 1-1-phenylcyclohexyl piperidine hydrochloride (Sernylan), on cerebral blood flow (CBF), brain metabolism and cerebrovascular CO2 responsiveness in primates. The experiments were carried out on immobilized and artificially ventilated baboons. Anesthesia was induced either with 100/mg/kg chloralose (i.p.) or with 1 mg/kg Sernylan (i.m.). CBF in 8 different brain regions was measured by the intra-arterial 133Xe clearance technique. The CO2 responsiveness of the cerebrovascular bed was tested by a gas mixture containing 5% CO2. Chloralose depressed total as well as regional CBF compared to the effect of Sernylan. A significant shift occurred toward lower CBF values in the grey matter while white matter flow was identical in the two groups. Brain O2 consumption was significantly higher during Sernylan analgesia (3.35 +/- 0.34 ml/100 g/min) than during chloralose anesthesia (2.42 +/- 0.22 ml/100 g/min). There were no differences in glucose uptake, lactate and pyruvate production, or in arterial and cerebral venous blood gases in the two types of anesthesia. The cerebrovascular CO2 sensitivity of the Sernylan-treated baboons was higher than that of the chloralose-anesthetized animals, in both the grey and white matter.
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PMID:Comparative effects of chloralose anesthesia and Sernylan analgesia on cerebral blood flow, CO2 responsiveness, and brain metabolism in the baboon. 40 48

1. In cats under pentobarbitone anaesthesia the effects of focal temperature changes of the ;chemoceptive' areas on the ventral surface of medulla, described by Loeschcke and his associates, were studied with respect to tidal volume, V(T), tidal variation in efferent phrenic activity, Phr(T), and respiratory rate. The cats were either paralysed and ventilated at various constant P(A,CO2) and P(a,O2) levels, or breathing spontaneously.2. It was confirmed that focal bilateral cooling of the intermediate, ;I((S))', areas caused rapid depression of respiration even at constant artificial ventilation. In normocapnic and normoxic conditions apnoea usually ensued at brain surface temperatures of 20-22 degrees C.3. The effects were graded along continuous temperature-response curves with enhancements of ventilation above and depression below normal body temperature.4. The strongest effects on V(T) and Phr(T) were obtained from the I((S)) areas with no or only small effects on inspiratory or expiratory timing in the vagotomized animal. The Hering-Breuer inflation reflex and its effects on timing and amplitudes were not affected by cooling this area.5. Focal cooling of the caudal or the rostral ;chemoceptive' areas, ;C((L))' and ;R((M))' areas, caused smaller effects on V(T) and Phr(T) but produced significant effects on respiratory rate even after vagotomy.6. The effects of focal cooling of these areas could be mimicked by topical application of procaine solution which has been shown not to penetrate deeper than 100 mum from the surface.7. Moderate focal cooling of area I((S)) to temperatures above 28-30 degrees C caused a parallel shift in the CO(2)-response (V(T), Phr(T)) curves to the right with little change in slope. The P(CO2) thresholds for apnoea were correspondingly raised. These focal temperature effects could be compensated by changes in P(CO2) with, on the average, 2.7 torr/ degrees C. Focal temperatures below 28 degrees C usually caused some decrease in slope of the CO(2)-response curves in addition to further shifts.8. Added hypoxic stimulus or electrical stimulation of the carotid sinus nerves caused an almost parallel increase of Phr(T) at all P(CO2) levels and all focal temperatures suggesting an additive type of interaction between the input from the peripheral chemoreceptors and that from the central (CO(2), H(+)) sensing structures whether the latter was altered by changing P(CO2) or by focal temperature changes on the I((S)) areas.9. In contrast to these effects of hypoxia and stimulation of the carotid sinus nerves the reflex increase of inspiratory activity caused by lung deflation or by electrical stimulation of the glossopharyngeal nerve distal to the carotid sinus nerves was CO(2) dependent. These reflex effects decreased with focal cooling of the I((S)) areas as with hypocapnia, suggesting a mainly multiplicative or ;gain-changing' type of interaction with the central chemoceptive drive.10. The close similarities in effect of focal cooling and of hypocapnia on the different respiratory parameters even during constant artificial ventilation indicate that focal temperature changes of the I((S)) areas intervene effectively with the normal ventilatory response to CO(2) without changing the chemical or physical environment of those neural structures in the brain stem which set respiratory pattern.
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PMID:Graded changes in central chemoceptor input by local temperature changes on the ventral surface of medulla. 43 Mar 96

Rats are made hypercapnic by breathing 8% CO2 for a week. Their stomachs, removed under anaesthesia in a hypercarbic atmosphere, are placed in a special chamber and the acidic secretion (free + titratable) is measured in vitro in relation to different parameters of the controlled atmosphere. The secretion depends on the gas composition. Under the same conditions (mucosa CO2 = 8%, serosa CO2 = 10%) the in vitro secretion of the hypercapnic subjects (n = 32) is lower than that in the normal rats (n = 27), the latter secretion decreasing more rapidly with the duration of the in vitro measurement. The differences between the hypercapnic and the control subjects are in the order of +/- 10% in titratable acidity (mEq/l/h/cm2) and +/- 20% in free acidity (muEq/l/h/cm2).
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PMID:[Effect of chronic hypercapnia on the gastric acid secretion in rats: a comparative study in vitro (author's transl)]. 45 65

The study of heartbeat variations of Bombyx mori larvae submitted to CO2 narcosis has provided new information on carbon dioxide anesthesia. Purely anoxiant action must be dismissed. Action at a nerve level is possible since CO2 produces the same effect as ether, which is a classical anesthetic.
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PMID:Studies on the anesthetic mechanism of carbon dioxide by using Bombyx mori larvae. 46 67

The central control mechanism of respiratory frequency under varied alveolar carbon dioxide pressure (PACO2 20--200 Torr) was investigated in anesthetized, vagotomized, immobilized, and artificially ventilated rabbits. Central inspiratory activity indicated by phrenic motor discharge was tolerant of the extensive hypercapnia. Under light anesthesia the respiratory frequency (f) decreased in a hyperbolic fashion with increasing PACO2. Under deeper anesthesia or after mesencephalic decerebration the hyperbolic f response to PACO2 was abolished or changed to a hill-type f response (initial increase and subsequent decrease in f) and, on the average, the changes in frequency were much less. We conclude that in the absence of vagal control the respiratory frequency is primarily determined by 1) the periodicity of the bulbopontine inspiratory activity, which is little dependent on PACO2, and 2) a suprapontine acceleratory mechanism, which is depressed by increased PACO2 and highly sensitive to anesthetics. The mechanism of changes in the type of f response to CO2 is discussed.
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PMID:Phrenic activity during severe hypercapnia in vagotomized rabbits. 46 79


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