Sodium bicarbonate buffers gastric acid during surgery in obstetric and gynecologic patients.
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Anesthesia, Obstetrical↗
Biomedical subjects
M F Roizen
Publications and source records attributed to M F Roizen.
Transesophageal echocardiographic monitoring of myocardial ischemia during vascular surgery.
Transesophageal echocardiography (TEE) was used to detect segmental ventricular wall motion abnormalities (SWMAs) associated with ischemia in 49 high-risk patients who had 50 major vascular procedures, including 23 infrarenal aortic, five suprarenal aortic, 14 carotid, seven distal, and one axillofemoral reconstructions. A modified gastroscope tipped with an echocardiographic transducer was inserted into the esophagus and positioned behind the heart to obtain a reproducible cross-sectional view of the left ventricle at the level of the papillary muscles. Twelve patients (24%) had SWMA at baseline, probably representing areas of old infarction. Fourteen patients (28%) had new intraoperative SWMAs. Ten of 14 patients were successfully treated and wall motion was normalized. One of the four patients with persistent SWMA suffered a nonfatal subendocardial infarct; another patient suffered intraoperative cardiac arrest and died. No infarcts were documented in the 10 patients successfully treated. The mortality rate in the entire high-risk group was 6%. Alterations in ventricular wall motion were noted in almost 50% of high-risk patients undergoing major vascular surgery. Seventy-one percent of acute SWMAs were reversed without any evidence of myocardial infarction. TEE allowed early recognition of evolving myocardial ischemia and facilitated immediate and specific fluid and pharamcologic interventions. Continued application of this technique may reduce the incidence and morbidity of perioperative cardiac complications.
Coronary Disease↗
Preoperative anxiety: does anxiety level the afternoon before surgery predict anxiety level just before surgery?
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Adult↗
Anaphylactic and anaphylactoid reactions. A review.
Anaphylaxis is a life-threatening, immunologically mediated reaction. "Anaphylactoid" reactions produce the same clinical syndrome but are not immunologically mediated. Vasoactive mediators of these reactions include histamine, eosinophilic chemotactic factors of anaphylaxis, slow reacting substance of anaphylaxis (a mixture of three leukotrienes, one a potent coronary vasoconstrictor), kinins, and prostaglandins. Symptoms usually occur within 15 minutes of parenteral injection of the causative agent, but can be delayed as long as 2.5 hours. Because vasodilation occurs at the capillary and postcapillary venule, resulting in loss of fluid and colloid (and hence reduction in effective plasma volume), and then shock, volume replacement is a mainstay of therapy. This article reviews the pathophysiology, incidence, and drug causes of anaphylactic/anaphylactoid reactions and proposes therapy to minimize the consequences of reactions seen by physicians treating spinal conditions.
Anaphylaxis↗
Contribution of sensory afferents and sympathetic efferents to joint injury in experimental arthritis.
We used pharmacological and surgical methods to determine the contribution of several neural components to joint injury in rats with adjuvant-induced arthritis. Both neonatal administration of capsaicin, which eliminates small-diameter afferents, and peripheral sympathectomy, which depletes catecholamines, attenuated joint injury. In contrast, the arthritis was more severe in spontaneously hypertensive rats, which have increased sympathetic tone. To address the contribution of the central vs peripheral afferent terminal selectively, a group of rats underwent unilateral dorsal rhizotomy. These rats developed a more severe arthritis in the deafferented limb. The increase in arthritis severity produced by dorsal rhizotomy could be reduced by prior sympathectomy or, less effectively, by prior treatment with capsaicin. The latter observation suggests that large-diameter afferents that are cut during dorsal rhizotomy also influence inflammation. Finally, intracerebroventricular injection of morphine attenuated the severity of arthritis, possibly through activation of bulbospinal sympathoinhibitory circuits. Taken together, these data indicate that no one class of nerve fiber is wholly responsible for the neurogenic component of inflammation in experimental arthritis but that large- and small-diameter afferents, sympathetic efferents, and CNS circuits that modulate those fiber systems all influence the severity of joint injury in arthritic rats.
Animals↗
The usefulness of preoperative laboratory screening.
We assessed the usefulness of routine laboratory screening of preoperative patients. Computer-readable laboratory, demographic, and discharge diagnostic data were assembled for 2,000 patients undergoing elective surgery over a four-month period, and randomly selected samples of patients were studied. Several tests ordered by protocol and performed by the laboratory at the time of admission were examined in these samples, including complete blood cell count, differential cell count, prothrombin time, partial thromboplastin time, platelet count, six-factor automated multiple analysis, and glucose level. Sixty percent of these routinely ordered tests would not have been performed if testing had only been done for recognizable indications, and only 0.22% of these revealed abnormalities that might influence perioperative management. Chart review indicated that these few abnormalities were not acted on nor did they have adverse surgical or anesthetic consequences. In the absence of specific indications, routine preoperative laboratory tests contribute little to patient care and could reasonably be eliminated.
Adolescent↗
Reduced anesthetic requirement after electrical stimulation of periaqueductal gray matter.
To determine whether electrical stimulation of the periaqueductal gray region decreases anesthetic requirement, the authors studied the effect of such stimulation on the MAC of halothane and 60% nitrous oxide in 33 patients. These patients, who were undergoing implantation of a radio-frequency-coupled receiver and connection of that receiver to electrodes previously implanted in the periaqueductal gray area, were assigned randomly to receive (n = 16) or not receive (n = 17) electrical stimulation 1 h before surgery. The mean value (+/- SEM) for the minimum alveolar concentration of halothane combined with 60% nitrous oxide was significantly less (P less than 0.001) for patients who were stimulated preoperatively (0.15 +/- 0.05%) than for those who were not (0.51 +/- 0.02%). The authors conclude that stimulation of the periaqueductal gray region decreases anesthetic requirements and believe that at least three mechanisms are possible: a nonspecific narcotic-like effect, a specific effect on a pain pathway, or an effect on specific neural pathways that affect anesthetic requirements secondary to changes in regional concentrations of neurotransmitters.
Anesthesia, Inhalation↗
Intraoperative pacemaker complications.
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Aged↗
Intraoperative detection of myocardial ischemia in high-risk patients: electrocardiography versus two-dimensional transesophageal echocardiography.
Because acute segmental wall motion abnormalities (SWMAs) of the left ventricle are highly sensitive and specific indicators of myocardial ischemia, this study compared the incidence and significance of ischemia, as detected by two-dimensional transesophageal echocardiography and surface electrocardiography, during anesthesia and surgery in patients at high risk of myocardial ischemia. During surgery, 24 of the 50 patients studied had new SWMAs, whereas only six had ST segment changes. All patients with ST segment changes also had new SWMAs: in three instances, SWMAs occurred before the ST segment change, and in three instances, they occurred simultaneously. All three patients who had intraoperative myocardial infarctions also had persistent intraoperative SWMAs, whereas only one patient had ST segment changes. Ten healthy patients requiring noncardiovascular surgery were monitored similarly; none of these had SWMAs, ST segment changes, or myocardial infarction. This study demonstrates the superiority of two-dimensional transesophageal echocardiography over electrocardiography for the intraoperative detection of myocardial ischemia. Furthermore, when new SWMAs persist to the conclusion of surgery, myocardial infarction is likely to have occurred.
Echocardiography↗
Adverse reactions to chemonucleolysis: anesthetic considerations.
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Anaphylaxis↗
Decreased incidence and mortality of anaphylaxis to chymopapain.
A recognized side effect of chemonucleolysis is life-threatening anaphylaxis to chymopapain. In the clinical trials of chymopapain, 13 cases of anaphylaxis were reported in 1585 administrations (0.82%). Two patients died. Data from a postmarketing survey (48,239 questionnaires) were reviewed to identify factors influencing the incidence and severity of anaphylaxis. The results indicate the incidence of anaphylaxis decreased to 0.44% in the 1983-1984 period (126/23,736), a level significantly (P less than or equal to 0.001) below the incidence of 0.82% observed in initial clinical trials. Only three deaths from complications related to anaphylaxis occurred in approximately 75,000 administrations (producing 252 anaphylactic episodes) reported since December 1982. The prophylactic use of antihistamines and pretreatment with intravenous fluids coincide with the dramatic reduction in mortality due to anaphylaxis. However, overdiagnosis of anaphylaxis in the clinical trials and avoidance of chemonucleolysis in patients with IgE antibodies to chymopapain may account, in part, for the reduction in incidence.
Adult↗
Anesthetic and surgical risk in hypothyroidism.
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Anesthesia↗
Current achievements and challenges in adrenal surgery.
Adrenal surgery is now done in almost ideal circumstances. Mortality and complications are rare except in Cushing's syndrome. All major adrenal hormones and their stimulators are measurable and discriminating tests abound. Imaging techniques detect small masses. Inhibitors of hormone synthesis and cell receptors allow amelioration of metabolic hazards preoperatively. Primary aldosteronism is first medically controlled, and patients are selected for operation if difficult to control and if the type of disease is responsive to adrenalectomy. Cushing's disease usually requires pituitary adenomectomy, but some of the 15-30 per cent failures, those with ectopic adrenocorticotrophic hormone (ACTH) producing tumours, or adrenal adenomas warrant adrenalectomy. Metabolic hazards are controlled pre-operatively by aminoglutethimide. Benefits of adrenalectomy are uncertain and many challenges remain. Hazards of phaeochromocytomectomy are avoided by pre-operative adrenergic blockade. Myocardial disease warrants delay. Small unilateral lesions of all types are best removed through unilateral approaches. Small masses found on imaging and without apparent effect can be observed.
Adenoma↗
Cardiovascular and metabolic sequelae of inducing anesthesia with ketamine or thiopental in hypovolemic swine.
If further sympathetic stimulation is neither possible nor desirable during moderate hypovolemia, anesthetic agents capable of sympathetic stimulation would not be advantageous for induction of anesthesia during hypovolemia. To test this hypothesis, 21 swine were studied during normovolemia and after 30% of their estimated blood volume was removed. Swine were divided randomly into three equal groups to receive no anesthetic or the minimal anesthetic dose of ketamine (6.65 +/- 0.38 mg/kg, iv) or thiopental (5.77 +/- 0.21 mg/kg, iv). After the initial response to hypovolemia, animals given no drug did not exhibit further changes during the hypovolemic period. Five minutes after induction of anesthesia in the hypovolemic state, ketamine, but not thiopental, caused large increases in plasma epinephrine, norepinephrine, and renin activity. Despite these differences, both anesthetics equally depressed systemic vascular resistance, mean systemic arterial blood pressure, heart rate, and cardiac output. Ketamine, but not thiopental, decreased stroke volume. Neither anesthetic affected oxygen consumption. Both anesthetics caused similar increases in blood lactate concentration. Thirty minutes after induction of anesthesia, plasma epinephrine, norepinephrine, and renin activity remained higher in animals given ketamine than in those given thiopental. Stroke volume, systemic vascular resistance, cardiac output, and oxygen consumption did not differ among groups; however, only the animals given ketamine showed further increase in blood lactate concentration and base-deficit. Thirty minutes after infusion of shed blood, cardiac output and blood lactate concentration were greater in the animals given ketamine than in those given thiopental or no anesthetic. Ninety minutes after infusion of shed blood, no differences existed among groups. The authors conclude that after moderate hemorrhage, further increase in circulating catecholamines is possible but that the levels achieved either exceed the maximal effective concentration at site(s) of action or their effects are overwhelmed by the depressant effects of ketamine.(ABSTRACT TRUNCATED AT 250 WORDS)
Acid-Base Equilibrium↗
Hemodynamic and two-dimensional transesophageal echocardiographic analysis of an anaphylactic reaction in a human.
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Anaphylaxis↗
Intraoperative urinary output does not predict postoperative renal function in patients undergoing abdominal aortic revascularization.
To determine whether intraoperative urinary output was predictive of postoperative renal function, mean urinary output and lowest hourly urinary output were measured in 137 patients during operation for aortic reconstruction. Pulmonary capillary wedge pressure was kept within normal limits. If urinary output was less than 0.125 ml X kg-1 X hr-1, patients were given crystalloid solution, mannitol, furosemide (Lasix), or nothing. For each patient, serum creatinine and blood urea nitrogen (BUN) levels were assayed on postoperative days 1, 3, and 7. There was no significant correlation between intraoperative mean urinary output or lowest hourly urinary output and change from preoperative to postoperative levels of creatinine or BUN. Twenty-one patients had postoperative renal insufficiency; of these, 17 had had renal disease before operation. In these patients as well; mean urinary output and the lowest hourly urinary output did not correlate with change in BUN or creatinine levels. The position of the aortic cross-clamp did not affect these correlations. Therefore, intraoperative urinary output was not predictive of postoperative renal insufficiency in patients undergoing aortic reconstruction.
Anuria↗
But what does it do to outcome?
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Anesthetics↗
Monitoring with two-dimensional transesophageal echocardiography. Comparison of myocardial function in patients undergoing supraceliac, suprarenal-infraceliac, or infrarenal aortic occlusion.
When the aorta must be temporarily occluded at the suprarenal or supraceliac levels during surgery, the resulting large increase in afterload may make the myocardium ischemic, even though systemic and pulmonary artery pressures and cardiac output are maintained at normal levels. These traditional indices of myocardial well-being do not appear to be sufficiently sensitive, since cardiac complications are still the most frequent cause of perioperative death and morbidity after aortic reconstruction. To evaluate two-dimensional transesophageal echocardiography as a monitor of myocardial well-being, we studied 24 American Society of Anesthesiologists physical status class III or IV adult patients who were undergoing aortic reconstruction and occlusion at the supraceliac (n = 12), suprarenal-infraceliac (n = 6), or infrarenal (n = 6) level. In addition to traditional monitors, we used a gastroscope tipped with a special 3.5 MHz two-dimensional echocardiographic transducer (Diasonics) that was placed in the esophagus to give a cross-sectional view of the left ventricle through the base of the papillary muscles. The hemodynamic effects of clamping the aorta were managed by administration of vasodilating drugs, anesthetics, and fluids to keep systemic and pulmonary arterial pressures normal. Occlusion at the supraceliac level caused major increases in left ventricular end-systolic and end-diastolic areas, decreases in ejection fraction, and frequent wall motion abnormalities; these changes were not detected by conventional monitoring devices. Occlusion at the suprarenal-infraceliac level caused similar but smaller changes, and occlusion at the infrarenal level caused only minimal cardiovascular effects. We conclude that the two-dimensional transesophageal echocardiogram offers promise as an intraoperative monitoring device.
Aged↗