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At least 631 records · Page 35Linked to original sources
PubMed2002

Frequency of hypotension and bradycardia during general anesthesia, epidural anesthesia, or integrated epidural-general anesthesia for total hip replacement.

STUDY OBJECTIVE: To evaluate the frequency of hypotension and bradycardia during integrated epidural-general anesthesia as compared with general anesthesia or epidural anesthesia alone. DESIGN: Prospective, randomized, open, multicenter study. SETTING: Inpatient anesthesia at 7 University or Hospital Departments of anesthesia. PATIENTS: 210 ASA physical status I, II, and III patients undergoing elective total hip replacement. INTERVENTIONS: Using a balanced randomization method, each hospital enrolled 30 consecutive patients who received integrated epidural-general anesthesia, epidural anesthesia, or general anesthesia. MEASUREMENTS AND MAIN RESULTS: Occurrence of clinically relevant hypotension (systolic arterial blood pressure (BP) decrease >30% from baseline), or bradycardia (heart rate (HR) <45 bpm) requiring pharmacologic treatment were recorded, as well as routine cardiovascular parameters. Clinically relevant hypotension during induction of nerve block was reported in 13 patients receiving epidural block (18%) and 16 patients receiving epidural-general anesthesia (22%) (p = 0.67). Subsequently, 22 of the remaining 54 patients in the epidural-general anesthesia group (41%) developed hypotension after the induction of general anesthesia, as compared with 16 patients of the general anesthesia group (23%) (p = 0.049). No differences in HR or in frequency of bradycardia were observed in the three groups. CONCLUSIONS: The induction of general anesthesia in patients with an epidural block up to T10 increased the odds of developing clinically relevant hypotension as compared with those patients who received no epidural block, and was associated with a twofold increase of the odds of hypotension as compared with the use of epidural anesthesia alone.

Aged↗
PubMedDate not supplied

[Free radicals in anesthesia and the role of exogenous antioxidants].

The alterations of the normal biological oxidoreductive balance can be due both to an increase of the plasmatic concentration of the free radical and the loss of the protective mechanisms. These conditions lead to the damages of cellular structure by the mechanism of lipoperoxidation. We have studied the lipoperoxidative effects of anesthetic drugs and the possible protective effect of the taurine. Two groups of 30 patients subjected to general anesthesia for a time of about 160 minutes, have been studied. The taurine has been administered in the second group, intravenously, before and during anesthesia. Blood samples were drawed in all patients in order to determinate plasmatic Malondialdehyde (MDA) and Glutathione peroxidase activities both in erythrocyte lysate and plasma. Our results revealed an increase of values of MDA and Glutathione peroxidase activities in the first group (without taurine). We think that this increase has been caused by the anesthetic drugs administration and that a protective cellular effect is developed by the taurine administration.

Adult↗
PubMed2001

'Balanced analgesia' in the perioperative period: is there a place for ketamine?

We investigated whether intraoperative 'subanesthetic doses' of ketamine have a postoperative anti-hyperalgesic and an analgesic effect and which is the preferential route of administration, either systemic (intravenous, i.v.) or epidural. One hundred patients scheduled for rectal adenocarcinoma surgery under combined epidural/general anesthesia were included. Before skin incision all the patients received an epidural bolus followed by an infusion of continuous bupivacaine/sufentanil/clonidine mixture. They were randomly assigned to receive no ketamine (group 1), i.v. ketamine at the bolus dose of 0.25 mg/kg followed by an infusion of 0.125 mg/kg per h (group 2), 0.5 mg/kg and 0.25 mg/kg per h (group 3), epidural ketamine 0.25 mg/kg and 0.125 mg/kg per h (group 4), or 0.5 mg/kg and 0.25 mg/kg per h (group 5). All i.v. and epidural analgesics were stopped at the end of surgery and patients were connected to an i.v. morphine patient-controlled analgesia (PCA) device. Short-term postoperative analgesia (72 h) was assessed by pain visual analog scale scores at rest, cough, and movements as well as by PCA requirements. Wound mechanical hyperalgesia was evaluated and residual pain was assessed by asking the patients at 2 weeks, and 1, 6, and 12 months. The area of hyperalgesia and morphine PCA requirements were significantly reduced in group 3. These patients reported significantly less residual pain until the sixth postoperative month. These observations support the theory that subanesthetic doses of i.v. ketamine (0.5 mg/kg bolus followed by 0.25 mg/kg per h) given during anesthesia reduce wound hyperalgesia and are a useful adjuvant in perioperative balanced analgesia. Moreover, they show that the systemic route clearly is the preferential route.

Aged↗
PubMed2003

[Comparison of requirement for postoperative analgesics after inhalation and total intravenous anesthesia].

BACKGROUND: We evaluated the requirement for postoperative analgesics in 88 patients undergoing abdominal total hysterectomy with inhalation anesthesia or with total intravenous anesthesia. METHODS: Anesthesia was induced in the inhalation anesthesia (GOS, n = 52) group with propofol and fentanyl, and maintained with sevoflurane, nitrous oxide balanced with oxygen, and additional administrations of fentanyl up to 0.2 mg in total. The patients in the total intravenous anesthesia (TIVA, n = 36) group were managed with target controlled infusion for propofol and intermittent administration of fentanyl. Effect site concentrations of fentanyl at the end of surgery were calculated using a pharmacokinetic-pharmacodynamic model. We divided the postoperative time course and evaluated the types, dosages, and prescription times of postoperative analgesics in each. RESULTS: Both total dosage and effect-site concentration of fentanyl were higher in the TIVA group than in the GOS group, and total prescription time in the TIVA group was significantly less during the 24 hrs after the operation. Supplemental prescription intervals of buprenorphine were significantly less in the TIVA group. Since administration of fentanyl during operation was adequate, patients in the TIVA group were considered to be in a sufficient analgesic state at the end of operation. CONCLUSIONS: The postoperative pain can be reduced with TIVA.

Adult↗
PubMed1998

[Effects of deep halothane and isoflurane anesthesia on cerebral as well as coronary metabolism].

Mongrel dogs were subjected to halothane or isoflurane to examine the relationship between systolic blood pressure and cerebral as well as myocardial metabolism. The oxygen and hydrogen ion balances in the brain were not disturbed in either group to the systolic blood pressure level of 70 mmHg and were well maintained in the isoflurane group below this level. The myocardial oxygen balance was not aggravated in either group, whereas, the myocardial hydrogen ion balance was disturbed in the halothane group at the systolic blood pressure level between 70 mmHg and 50 mmHg though it was preserved in the isoflurane group. These findings demonstrate that the systolic blood pressure not disturbing oxygen and hydrogen ion balances in the brain and myocardium is 70 mmHg during halothane or isoflurane anesthesia, while isoflurane anesthesia becomes advantageous at the systolic blood pressures below this level. While the myocardial metabolism is less affected by lowering of blood pressures than the cerebral metabolism, it seems important to secure cardiac functions to maintain metabolism in both organs.

Anesthesia, Inhalation↗
PubMed1996

Heart rate variability during artificial ventilation and apnea in brain-damaged rabbits.

The effect of artificial ventilation, apnea, and norepinephrine administration on heart rate variability was determined in brain-damaged rabbits. Electrocardiographic R-R intervals and circulatory variables were measured for 5 min at three different ventilatory frequencies, including apnea under isoflurane general anesthesia. The same measurements were repeated after brain damage was inflicted by an inflated intracranial balloon. In control rabbits (n = 8) and in those receiving norepinephrine (n = 8), power spectral analysis of R-R intervals was repeated, and spectral components of low (LF: 0.04-0.09 Hz), mid (MF: 0.09-0.15 Hz), and high (HF: 0.15-0.40 Hz) frequency band areas were assessed. LF + MF (P < 0.05) increased during apnea, whereas HF did not change under general anesthesia. However, after brain damage in both groups LF + MF did not change, whereas HF was depressed (P < 0.05). There was no intergroup difference in decreases of HF/(LF + MF) (P < 0.05) during apnea under either condition. Norepinephrine increased heart rate and arterial pressure (P < 0.05) but did not produce any intergroup difference in the spectral components. We suggest that sympathovagal balance is apt to be sympathotonic during apnea under general anesthesia, whereas it is vagolytic with brain damage.

Animals↗
PubMedDate not supplied

Quality in anesthesia care: lessons from industry and a proposal for valid measurement and improvement.

Quality anesthetic care is a goal fundamental to our tradition and our training, but defining and measuring quality in anesthesia presents special challenges. Industrial models of quality, especially those so fundamental to the re-emergence of post-war Japan, deserve careful study and are discussed at some length, but they clearly have limitations in understanding quality in anesthesiology. We suggest that most current quality efforts are inherently flawed. Whether or not they rigorously attempt to define quality, they are hampered by lack of data concerning outcomes and alternatives, as well as lack of distinction between quality and efficacy. Quality efforts in American medicine and anesthesiology seem mired in a "criterion of potential benefit," which is still central to many of our prescriptions for individual medical care. Current quality improvement efforts do not seem well suited to correct these flaws. Anesthetic care, and that of American medicine in general, is fragmented, enormously costly, and sometimes inappropriate or poor. Anesthesiologists are suspicious of current quality efforts to improve this care. The system often seems more geared to eliminate bad apples than to improve patient care. Because anesthesia is a specialty that facilitates care but seldom "cures," we face greater challenges in studying and defining quality than do other specialties. Because of this, it is imperative that several principles govern future quality improvement efforts in anesthesiology. First, a reasonable balance must be attained between study of outcomes and processes of anesthesia care. Second, anesthesia-specific severity of illness indexing must be developed. Third, and perhaps most important, anesthetic processes and outcomes must be reported on a national level. Fundamental to future quality efforts in our specialty, we believe, is the establishment of a protected National Anesthesia Outcome Registry. This article reviews the industrial and medical history of quality, its measurement and improvement, and attempts to apply principles learned over many decades to anesthesiology.

Anesthesia Department, Hospital↗
PubMed2002

Effects of dexamethasone on intravascular and extravascular fluid balance in patients undergoing coronary bypass surgery with cardiopulmonary bypass.

BACKGROUND: Cardiac surgery with cardiopulmonary bypass is often associated with postoperative hemodynamic instability. In this regard beneficial effects of corticosteroids are known. The purpose of this study was to investigate whether these effects are due mainly to a modification of the intravascular and extravascular volume status or whether a more direct improvement of cardiovascular performance by corticosteroids is the underlying mechanism. METHODS: Twenty patients undergoing elective coronary bypass grafting were included in this randomized double-blind study. Patients of the treatment group received 1 mg/kg-1 dexamethasone after induction of anesthesia. In addition to the use of standard monitors and detailed fluid balance assessments, the transpulmonary double-indicator technique was used to measure extravascular lung water, total blood volume, and intrathoracic blood volume. Measurements were done after induction of anesthesia and 1 h, 6 h, and 20 h after the end of surgery. RESULTS: After cardiopulmonary bypass, no relevant increase in extravascular lung water was observed, despite highly positive fluid balances in all patients. A significantly smaller increase in extravascular fluid content was observed in the dexamethasone group. Total blood volume and intrathoracic blood volume did not differ in the two groups. Patients pretreated with dexamethasone had a decreased requirement for vasoactive substances and, in contrast with the control group, no increase in pulmonary artery pressure. CONCLUSIONS: Extravascular fluid but not extravascular lung water is increased in patients after surgery with cardiopulmonary bypass. Pretreatment of adult patients with 1 mg/kg-1 dexamethasone before coronary bypass grafting decreases extravascular fluid gain and seems to improve postoperative cardiovascular performance. This effect is not caused by a better intravascular volume status.

Adult↗
PubMedDate not supplied

Spinal anesthesia: practical applications.

The recent widespread popularity of spinal anesthesia can be traced to two events. One is the appreciation that, when used for operations below the level of the umbilicus, anesthetically induced physiologic trespass is less with spinal than with general anesthesia. The other is the recognition that modest hypotension with peripheral vasodilation, that may be seen with spinal anesthesia or intravenous infusion of nitroprusside, is, unlike hypotension associated with hypovolemia, unaccompanied by physiologically significant changes in peripheral distribution of cardiac output or changes in the balance between tissue oxygen supply and demand in the myocardium or elsewhere. Spinal anesthesia also has special advantages specific to urinary tract surgery in the geriatric patient.

Age Factors↗
PubMed1998

Protective effects of moderate hypothermia on behavioral deficits but not necrotic cavitation following cortical impact injury in the rat.

A number of experimental studies have reported that moderate hypothermia can produce significant protection against behavioral deficits and/or morphopathological alterations following traumatic brain injury; a Phase 3 clinical trial is currently examining the therapeutic potential for moderate hypothermia (32 degrees C) to improve outcome following severe traumatic brain injury in humans. The current study examined whether hypothermia (32 degrees C) provided behavioral protection following experimental cortical impact injury. The extent of focal cortical contusion was also examined in the same rats. A total of 30 male Sprague-Dawley rats were trained on beam balance and beam walking tasks prior to injury. Under isoflurane anesthesia, cortical impact was produced on the right parietal cortex of 20 rats. Ten rats underwent all surgical procedures but were not impacted (sham-injured rats). Ten of the injured rats were cooled to 32 degrees C (measured in temporalis muscle) beginning 5 min postinjury, maintained for 2 h and rewarmed slowly for 1 h. In the other 10 injured rats, normothermic temperatures (37.5 degrees C) were maintained for the same duration. Beam balance and beam walking performance was assessed daily for 5 days following injury. At 11 days postinjury, rats were assessed for 5 days on acquisition of the Morris water maze task. Following behavioral assessments, rats were perfused and the brain removed. Coronal sections were cut through the site of cortical impact injury and stained with hematoxylin and eosin. Hypothermic treatment resulted in significantly less beam balance and beam walking deficits than observed in normothermic rats. Hypothermia also significantly attenuated spatial memory performance deficits. Quantitative morphometric analyses failed to detect any significant differences in volumes of necrotic tissue cavitation in cortices of hypothermic and normothermic rats. Hypothermic treatment also had no effect on volumes of dorsal hippocampal tissue or numbers of cells in CA1 or CA3 regions of the hippocampus. These data suggest that hypothermia, consistent with the reports of others, can produce significant behavioral protection following cortical impact injury that is not necessarily correlated with changes in focal cortical necrosis within the first 15 days following injury.

Animals↗
PubMed1983

Effect of halothane on cardiac output and regional flow in the fetal lamb in utero.

We studied the effect of halothane on the fetal cardiovascular system of six lambs in utero by measuring fetal heart rate and femoral arterial blood pressure and by injecting labeled microspheres during a control period and again after 60 and 90 min of halothane anesthesia administered to six pregnant ewes at an inspired concentration of 1.5%. There were no significant effects on maternal cardiovascular function or acid-base balance, but fetal blood pressure decreased significantly by 27% after 8 min of halothane anesthesia and remained at this level for the duration of the experiment. However, there were no significant changes either in fetal regional blood flow to the vital organs or in fetal cardiac output. Fetal oxygenation and acid-base status remained stable. We conclude that in normal fetal lamb in utero the decrease in mean fetal arterial blood pressure associated with maternal halothane anesthesia is due to a decrease in peripheral vascular resistance because regional blood flow and acid-base status are well maintained.

Anesthesia, Inhalation↗
PubMed2001

Activation of serotonergic pathways from the midbrain raphe system to the subfornical organ by hemorrhage in the rat.

The role of serotonergic neural pathways from the midbrain raphe nuclei to the subfornical organ (SFO) in the central regulation of cardiovascular function and body fluid balance was investigated in adult male rats under urethane anesthesia. Eleven neurons in the dorsal raphe nucleus (DR) were antidromically activated by electrical stimulation of the SFO. Of these neurons, 6 displayed an excitatory response following hemorrhage (10 ml/kg bwt) while the remaining 5 neurons were unresponsive. Ninety-four neurons in the SFO were tested for a response to electrical stimulation of the DR or hemorrhage. Electrical stimulation of the DR caused orthodromic excitation (19%) or inhibition (5%) of the activity of SFO neurons. In 14 of 18 SFO neurons that displayed the excitation to the stimulation of the DR, hemorrhage (30 to 50 mm Hg suppression in mean arterial pressure) produced an increase of their discharge, while the stimulus was without effect in the remaining neurons responsive to the stimulation of the DR. The effects of hemorrhage on serotonin (5-HT) release in the region of the SFO were examined using intracerebral microdialysis techniques. Hemorrhage significantly increased 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) concentrations in the region of the SFO. The present data suggest that the serotonergic pathways from the DR to the SFO may relay activation of the peripheral baroreceptors to SFO neurons which result in enhanced excitability, indicating the involvement of the pathways in the regulation of cardiovascular function.

Action Potentials↗
PubMed2002

Anesthetics and the brain.

The action of anesthetics on the nervous system can be understood by considering their possible interactions with neuronal function. Anesthesia may be produced by a change in the balance of inhibitory synapses (notable via GABAa receptors) and excitatory synapses (notably glutamate receptors). Our knowledge of the specific mechanisms of anesthetic drugs and the structures in the CNS remains inadequate to explain the anesthetic state by one mechanism. The action of anesthetics can also be considered based on the action of the drugs on cerebral physiology, notably CMR, CBF, metabolic coupling, and autoregulation. Some specific anesthetic recommendations can be made for certain neurosurgical procedures and pathology based on the effects on physiology.

Anesthetics↗
PubMed2001

Effects of arteriovenous extracorporeal therapy on hemodynamic stability, ventilation, and oxygenation in normal lambs.

OBJECTIVE: To evaluate hemodynamic stability and gas exchange in a neonatal animal model of pumpless arteriovenous extracorporeal membrane oxygenation (AV-ECMO) with extracorporeal shunt flow of up to 15% of cardiac output during variable ventilation and oxygenation. DESIGN: Prospective study. SETTING: Research laboratory in a hospital. SUBJECTS: Seven lambs (5.5 +/- 0.6 kg, mean +/- sd). INTERVENTIONS: The lambs initially were anesthetized by 50 mg/kg ketamine intravenously. After tracheostomy, the lambs were mechanically ventilated and paralyzed by using 1 mg/kg vecuronium bromide followed by 0.1 mg.kg(-1).hr(-1). One femoral vein was cannulated with a pulmonary artery flotation catheter and used for cardiac output and pulmonary artery pressure measurements. A femoral artery was cannulated for measuring mean arterial blood pressure, measuring heart rate, and blood sampling for gas exchange analyses. Finally, the right internal jugular vein and carotid artery were cannulated and used for the AV-ECMO. Normothermia (38 +/- 0.5 degrees C), fluid balance (5 mL.kg(-1).hr(-1) normal saline), and anesthesia (5 mg.kg(-1).hr(-1), intravenous ketamine) were maintained. Ventilator settings were adjusted to establish a baseline Paco2 (25-35 mm Hg) at an Fio2 of 0.4. The AV-ECMO circuit was established by using a hollow fiber oxygenator, primed with maternal sheep blood (150-200 mL). MEASUREMENTS AND MAIN RESULTS: The physiologic effects of the AV-ECMO shunt were evaluated at 15, 25, and 40 mL.kg(-1).hr(-1) ECMO flow, corresponding roughly to 4%, 8%, and 15% of the cardiac output values. The baseline minute volume was maintained during stepwise increases in arteriovenous shunt. A significant increase in endogenous cardiac output occurred at arteriovenous shunt of 25 and 40 mL.kg(-1).hr(-1) (analysis of variance followed by Tukey-Kramer multiple comparisons test), which was attributed to a significant increase of 30% in the heart rate. Effective cardiac output (difference between the thermodilution value and the AV-ECMO flow rate) and mean arterial blood pressure were not significantly changed. CO2 removal, measured at 15% arteriovenous shunt, was significantly increased with decreasing ventilation to 25% and 50% of the baseline (analysis of variance and Tukey-Kramer test). Oxygenation through the membrane was measured after reducing inspired Fio2 from 0.4 to 0.21, 0.15, and 0.10 with 15% arteriovenous shunt and baseline minute ventilation. Oxygen delivery by the oxygenator was significantly increased at Fio2 of 0.10, providing a maximum of 19.5% of the total oxygen consumption at an arterial hemoglobin-oxygen saturation of 60%. CONCLUSIONS: Healthy lambs are capable of maintaining effective cardiac output in the presence of moderate arteriovenous shunts (15%). AV-ECMO may provide efficient ventilatory support in the neonatal population with hypercapnia. The amount of oxygen delivery with AV-ECMO depends on arterial desaturation.

Animals↗
PubMed1990

Myocardial protection: what the anesthesiologist does.

The role of the anesthesiologist in myocardial protection is to optimize myocardial oxygen balance during the perioperative period. Nonpharmacological steps that can be taken to achieve this revolve around maintaining a satisfactory hemoglobin concentration and oxyhemoglobin saturation through maximizing ventilation. In addition, alkalosis and hypothermia should be prevented since they cause a left shift of the oxyhemoglobin dissociation curve, thus interfering with tissue oxygen delivery. Hypocarbia increases coronary vascular resistance. Blood volume must be adequate with an optimal hemoglobin concentration. Pharmacological measures should also be used, and it is important to continue through the perioperative period any previously administered cardioactive drugs. Furthermore, in the prebypass period, tachycardia may not be controlled by anesthetics; unless the tachycardia is paroxysmal, beta blockers are the drugs of choice. Depending on the cause, diastolic hypotension also needs to be treated either with volume, vasoconstrictors, or inotropes. Likewise, major hypertension can produce increased demand and, again depending on the cause, either anesthetics, vasodilators, beta blockers, or calcium blockers may be useful. Finally, myocardial ischemia without obvious cause probably should be treated with nitroglycerin or calcium blockers. During surgery, the effect of the anesthetic drugs on myocardial oxygen balance is important.

Anesthesia↗
PubMed2002

585-nm pulsed dye laser treatment of glottal papillomatosis.

Treatment of recurrent respiratory papillomatosis of the glottis is often challenging. The surgeon and patient must cooperatively balance decisions regarding airway safety, effects of multiple general anesthesias, employment disturbance, and vocal dysfunction. A pilot study was done in 41 adult cases (23 patients; 78 vocal folds) without complication to evaluate the effectiveness of a 585-nm pulsed dye laser (PDL; 450-micros pulse width; fluence of 38 to 255 J/cm2; 1- to 2-mm spot size) in the treatment of this disorder. Thirty-seven of the 41 cases (90%) were bilateral disease. Twenty-six of the 41 cases (63%; including 20 cases with involvement of the anterior commissure) were treated by bilateral photocoagulation of the lesions' microcirculation without microflap resection of tissue. Clinical observation revealed that irradiated but unresected disease involuted without development of an anterior commissure web. In the initial 13 of the 41 cases (32%), PDL treatment was followed by cold instrument microflap resection. The PDL enhanced the epithelial excision by improving hemostasis and by creating an optimal dissection plane between the basement membrane and the underlying superficial lamina propria. The PDL at 585 nm was less effective in the management of exophytic lesions because of its limited depth of penetration (approximately 2 mm). In this initial trial, the PDL was a relatively safe and efficacious treatment for glottal recurrent respiratory papillomatosis. Since the lesions involute without complete resection of the diseased epithelium, the anterior commissure can be treated to minimize the number of procedures. To study patterns of recurrence will require longer follow-up.

Female↗