Do we all need to have TEE capability?
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Anesthesiology↗
Biomedical subjects
R I Hall
Publications and source records attributed to R I Hall.
Trans-hepatic proximal migration of percutaneous-endoscopic biliary stent presenting as an abdominal wall abscess.
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Abdominal Muscles↗
Ampullary somatostatinoma associated with von Recklinghausen's neurofibromatosis presenting as obstructive jaundice.
A case of von Recklinghausen's disease associated with a somatostatinoma of the pancreas causing obstructive jaundice is described. Discussion on the association of von Recklinghausen's disease with somatostatinoma is presented.
Adult↗
Detection of intraoperative myocardial ischaemia--a comparison among electrocardiographic, myocardial metabolic, and haemodynamic measurements in patients with reduced ventricular function.
This study determined the sensitivity and specificity of haemodynamic and ECG monitors to detect the development of intraoperative myocardial ischaemia utilizing myocardial lactate production as the standard. In 29 patients with reduced ejection fraction (0.27-0.50) undergoing coronary artery revascularization, measurements were made at the awake, post-induction, post-intubation, first skin incision, post-sternotomy, pre-protamine, immediately post-cardiopulmonary bypass, and skin suture intervals. At each interval, measurement of a haemodynamic profile (including pulmonary artery occlusion (PAOP) and central venous (CVP) pressures, heart rate, and pressure rate quotient); myocardial lactate extraction and flux; changes in ST segments in ECG leads, V5 and II utilizing a Siemens 1280 intraoperative monitor, and a Marquette 8500 Holter monitor utilizing leads V5, V2, and AVF were made. "Ischaemia" was considered to be present when myocardial lactate production (MLP) occurred, PAOP or CVP increased by 5 mmHg above the baseline value, the pressure rate quotient was < 1, or ST segment deviation (> 1 mm) occurred in any lead for > 1 min. Variables positive when MLP was positive were the pressure rate quotient (sensitivity 32.8%, specificity 71.9%), CVP (sensitivity 10.9%, specificity 92.6%), and PAOP (sensitivity 1.6%, specificity 99.2%). Holter monitoring had a 100% positive predictive value but poor sensitivity (1.6%). The ECG (Lead V5 + II) measures of ischaemia were insensitive (17.5%) and relatively non-specific (87.7%). We conclude that, in this patient group and using myocardial lactate production as the standard, the pressure rate quotient, elevations in CVP or PAOP, or ST segment changes are insensitive measures of intraoperative myocardial ischaemia.
Aged↗
Does hemoglobin concentration affect perioperative myocardial lactate flux in patients undergoing coronary artery bypass surgery?
Increasing concern over complications related to blood transfusions has prompted a reevaluation of what constitutes an "adequate" perioperative hemoglobin concentration, particularly in patients undergoing coronary artery bypass graft (CABG) surgery. Data from 224 patients with preserved ventricular function (ejection fraction > 50%), undergoing CABG surgery, previously studied under a variety of anesthetic protocols, were reexamined to determine the effect of hemoglobin (HGB) concentration on myocardial lactate flux (MLF) (as an index of ischemia). The interaction of MLF and HGB concentration, anesthetic technique (ANES), and hemodynamic variables (including systemic and pulmonary arterial pressures (SAP and PAP), cardiac output (CO), and myocardial oxygen consumption (MVO2) was determined from a pool of 1598 data sets obtained from 224 patients. Data were collected from just prior to induction of anesthesia until 24 h postoperatively. Univariate analysis revealed a statistically significant relationship between MLF and HGB concentration (P < 0.001) but the correlation coefficient was only 0.09. Multiple regression analysis did not determine HGB concentration to be a significant independent term affecting MLF in either the overall group or in a subgroup of 22 patients having an adverse outcome (myocardial infarction, stroke, or death). For patients undergoing CABG surgery, HGB concentrations within the range of 58-172 g/L were not a significant variable in production of global myocardial ischemia as evidenced by MLF. This suggests that HGB concentrations as low as 60-70 g/L in the perioperative period are well tolerated and are not associated with an increased incidence of myocardial ischemia.
Adult↗
Anaesthesia for coronary artery surgery--a plea for a goal-directed approach.
The purpose of the current literature review was to examine whether changes in current anaesthetic techniques are warranted for patients undergoing coronary artery surgery in light of recent information presented in the literature. The objectives of a cardiac anaesthetic technique are to maintain haemodynamic stability and myocardial oxygen balance, minimize the incidence and severity of ischaemic episodes, be aware of cardiopulmonary bypass-induced pharmacokinetic changes, and facilitate early tracheal extubation if appropriate. Many techniques have been utilized. Provided attention is paid to the details of managing myocardial oxygen supply and demand, none has emerged as superior in preventing intraoperative myocardial ischaemia. Silent myocardial ischaemia (i.e., ischaemia occurring in the absence of haemodynamic aberrations) is common throughout the perioperative period and may occur even in the presence of an appropriately used anaesthetic technique. The incidence and severity appear to be greatest in the postoperative period when the effects of anaesthesia are dissipating. The use of high-dose opioid anaesthesia may no longer be the most appropriate technique to facilitate the anaesthetic objectives. The role of pain management in altering the incidence of ischaemia requires further study. Increased waiting lists for cardiac surgery and ever-diminishing resources should prompt a re-evaluation of early extubation (i.e., within eight hours) as a method of improving utilization of scarce ICU resources. It is suggested that this should be possible with currently available agents to achieve the anaesthetic objectives. Future suggestions for research in this area are made.
Anesthesia, General↗
Does hypothermia or hyperventilation affect enflurane MAC reduction following partial cardiopulmonary bypass in dogs?
This study in dogs determined the effect of systemic cooling and arterial hypocarbia during cardiopulmonary bypass (CPB) on the requirements for enflurane anaesthesia (MAC) before and after CPB. Twelve mongrel dogs were each anaesthetized with enflurane in oxygen on two separate occasions. End-tidal enflurane concentration was measured with a Puritan-Bennett Anaesthesia Agent Monitor. Using the tail-clamp method, MAC was determined twice with a one-hour interval between measurements (MAC 1 and MAC 2). Partial CPB was then initiated using femoral arterio-venous cannulation and maintained for one hour. Following separation from CPB, MAC was again determined twice with a one hour interval between measurements (MAC 3 and MAC 4). Dogs were randomly assigned according to PaCO2 management during CPB (low, 17.6 +/- 8.6 mmHg vs high, 38.9 +/- 11.5 mmHg), and then subjected to two experimental conditions. The first experiment on each dog was undertaken using normothermia during CPB (warm, 35-37 degrees C) while the second experiment (at least two weeks later) was conducted using hypothermia during CPB (cold, 30 degrees C). Analysis of the data, using ANOVA for repeated measures, revealed MAC 3 (1.95 +/- 0.33%, post-CPB) to be reduced when compared with MAC 1 (2.18 +/- 0.28%, P < 0.01) or MAC 2 (2.10 +/- 0.22%, P < 0.01), determined before CPB. Multivariate repeated measures analysis revealed no independent effects of hypothermia or arterial hypocarbia during CPB, on MAC reduction. By the time of the second experiment in each dog (two weeks later), MAC had returned to baseline levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Anesthesia, Inhalation↗
Anesthetic requirements decrease after cardiopulmonary bypass.
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Anesthetics↗
Fentanyl plasma concentrations maintained by a simple infusion scheme in patients undergoing cardiac surgery.
The ability of a simple infusion scheme for fentanyl to achieve and maintain one of two target concentrations of fentanyl in plasma was studied in 17 patients having cardiac surgery that required the use of moderate hypothermic cardiopulmonary bypass (CPB). All patients received preanesthetic medication including morphine, a benzodiazepine, and/or scopolamine. Anesthesia was induced and maintained by one of two fentanyl infusion regimens: HIGH-FEN (n = 6), a priming infusion of 2.4 micrograms.kg-1 x min-1 for 20 min in combination with a continuous infusion of 0.3 microgram.kg-1.min-1 for the duration of the operation to produce a plasma fentanyl concentration of 20-25 ng/mL; or LOW-FEN (n = 11), priming and maintenance infusions of 2.4 and 0.15 micrograms.kg-1 x min-1 designed to produce a fentanyl concentration of 12-15 ng/mL of plasma. The six patients receiving HIGH-FEN had plasma fentanyl concentrations maintained between 20 and 27 ng/mL and none required anesthetic supplementation before CPB; one patient required a single dose of thiopental 50 mg after the termination of CPB. The total fentanyl dose for the operation (3.2 +/- 0.1 h) averaged 107 +/- 2 micrograms/kg (range 100.5-115.5 micrograms/kg). The 11 patients receiving LOW-FEN had a plasma fentanyl concentration maintained below 20 ng/mL (range 13-17 ng/mL). Eight patients before and 10 patients after CPB required anesthetic supplementation for adverse hemodynamic or somatic responses. For comparison purposes, another eight patients received a single 75 micrograms/kg dose of fentanyl during 20 min for induction of anesthesia, and 7 of the 8 required supplemental anesthetic agents before and after CPB.(ABSTRACT TRUNCATED AT 250 WORDS)
Anesthesia, General↗
Myocardial metabolic and hemodynamic changes during propofol anesthesia for cardiac surgery in patients with reduced ventricular function.
This study examined the hypothesis that the use of propofol for induction and maintenance of anesthesia in patients with reduced ejection fraction (< 0.5) undergoing coronary artery revascularization would not be associated with a greater degree or incidence of myocardial ischemia as compared to patients receiving a moderate dose sufentanil-enflurane anesthetic technique. Two groups of patients were assigned randomly to receive one of two propofol anesthetic regimes. Group A (n = 21) received propofol 1-2 mg/kg as the induction drug and sufentanil 0.03 micrograms.kg-1.min-1 (fixed rate) plus propofol 50-200 micrograms.kg-1.min-1 (variable rate) infusions for maintenance of anesthesia. Group B (n = 21) received sufentanil 5 micrograms/kg for induction and propofol 50-200 micrograms.kg-1.min-1 (variable rate) infusion for maintenance of anesthesia. For comparison, a third group (Group C, n = 18) was studied subsequently. This group received sufentanil 5 micrograms/kg for induction of anesthesia which was maintained with enflurane. Adverse hemodynamic changes (hypertension, tachycardia) were managed by additional propofol (Groups A and B), sufentanil (Group C), or vasopressors (hypotension). Hemodynamic and myocardial metabolic profiles were measured when awake and sedated and at postinduction, postintubation, postincision, poststernotomy, and precardiopulmonary bypass times. Ischemia was assessed by measuring myocardial lactate production. The incidence of myocardial lactate production was reduced in Group B as compared to Group C (Group A, 45/126; Group B, 23/126; Group C, 58/107; P < 0.05). Myocardial lactate flux declined in all groups as surgery progressed; but apart from the reduction in flux (indicative of increased ischemia) noted in Group C versus Group B postinduction, no between-group differences were detected.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Esmolol--just another beta blocker?
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Adrenergic beta-Antagonists↗
A comparison of the myocardial metabolic and haemodynamic changes produced by propofol-sufentanil and enflurane-sufentanil anaesthesia for patients having coronary artery bypass graft surgery.
The purpose of this study was to compare propofol-sufentanil with enflurane-sufentanil anaesthesia for patients undergoing elective coronary artery bypass graft (CABG) surgery with respect to changes in (1) haemodynamic variables; (2) myocardial blood flow and metabolism; (3) serum cortisol, triglyceride, lipoprotein concentrations and liver function; and (4) recovery characteristics. Forty-seven patients with preserved ventricular function (ejection fraction greater than 40%, left ventricular end diastolic pressure less than or equal to 16 mmHg) were studied. Patients in Group A (n = 24) received sufentanil 0.2 microgram.kg-1 and propofol 1-2 mg.kg-1 for induction of anaesthesia which was maintained with a variable rate propofol (50-200 micrograms.kg-1.min-1) infusion and supplemental sufentanil (maximum total 5 micrograms.kg-1). Patients in Group B (n = 23) received sufentanil 5 micrograms.kg-1 for induction of anaesthesia which was maintained with enflurane and supplemental sufentanil (maximum total 7 micrograms.kg-1). Haemodynamic and myocardial metabolic profiles were determined at the awake-sedated, post-induction, post-intubation, first skin incision, post-sternotomy, and pre-cardiopulmonary bypass intervals. Induction of anaesthesia produced a larger reduction in systolic blood pressure in Group A (156 +/- 22 to 104 +/- 20 mmHg vs 152 +/- 26 to 124 +/- 24 mmHg; P less than 0.05). No statistical differences were detected at any other time or in any other variable including myocardial lactate production (n = 13 events in each group), time to tracheal extubation and time to discharge from the ICU. We concluded that, apart from hypotension on induction of anaesthesia, propofol-sufentanil anaesthesia produced anaesthetic conditions equivalent to enflurane-sufentanil anaesthesia for CABG surgery.
Adult↗
Less than additive antinociceptive interaction between midazolam and fentanyl in enflurane-anesthetized dogs.
The anesthetic interactions of midazolam and fentanyl were determined in terms of enflurane MAC reduction in dogs. In part 1, 8 animals received an intravenous (iv) loading dose of fentanyl followed by a constant infusion at 0.05 micrograms.kg-1.min-1 to produce a stable enflurane MAC reduction of approximately 20%. Midazolam was then administered in a series of three incremental loading doses and infusions (2.4, 9.6, and 28.8 micrograms.kg-1.min-1 previously determined to produce enflurane MAC reductions of approximately 30, 45, and 60%, respectively. Enflurane MAC was determined for each infusion. Then fentanyl was discontinued; naloxone 1 mg/kg was administered; and enflurane MAC was determined. In part 2, six dogs received a loading dose and a continuous infusion of fentanyl (0.2 micrograms.kg-1.min-1) designed to produce a stable enflurane MAC reduction of approximately 40%. A series of two incremental loading doses and infusions of midazolam (2.4 and 28.8 micrograms.kg-1.min-1) were added, and MAC determinations were repeated at each infusion rate. Then midazolam was discontinued; flumazenil (RO 15-1788) 1.5 mg/kg was administered; and enflurane MAC was determined. The fentanyl concentrations in plasma remained stable at 1.0 +/- 0.3 ng/ml (mean +/- standard deviation [SD], part 1) and 3.1 +/- 0.5 ng/ml (part 2) throughout the study and, in the absence of midazolam, reduced enflurane MAC by 28 +/- 11 and 44 +/- 5%, respectively. The addition of midazolam produced significant further reductions in enflurane MAC, but the reductions were less than those predicted on the basis of an additive interaction. Naloxone returned enflurane MAC reduction to that expected for midazolam alone (part 1).(ABSTRACT TRUNCATED AT 250 WORDS)
Anesthesia, Inhalation↗
Assessing the adequacy of fentanyl anesthesia: plasma concentrations and lower esophageal contractility.
Assessing the adequacy of anesthesia in the paralyzed patient is usually based on sympathetic and hemodynamic responses to noxious stimulation. Absence of such responses does not guarantee adequate anesthesia. A device monitoring the amplitude of provoked lower esophageal, contractility (PLEC) and the rate of spontaneous lower esophageal contractility (SLEC) has been developed as a potential monitor of the adequacy of anesthesia. This study determined the reliability of this device for monitoring anesthetic depth in 20 patients receiving fentanyl infusions who were undergoing coronary artery surgery and who were hemodynamically stable in the preoperative period. Premedication included midazolam 0.05 mg/kg i.m. and ranitidine 2 mg/kg p.o. Anesthesia was induced with fentanyl 50 micrograms/kg administered over 10 min and maintained by a fentanyl infusion 0.2 micrograms.kg-1.min-1. Following endotracheal intubation, a disposable esophageal monitoring probe, equipped with provoking and measuring balloons, was inserted and both the amplitude of provoked (PLEC) and the rate of spontaneous lower esophageal contractions (SLEC) were displayed and recorded. Precisely defined clinical signs of inadequate anesthesia included both somatic and hemodynamic responses to noxious stimulations. The presence of these responses was correlated with PLEC and SLEC and with fentanyl concentrations in plasma at specific times of noxious stimulation during the period preceding initiation of cardiopulmonary bypass. A total of 208 episodes of noxious stimulation were recorded at insertion of the nasal temperature probe (n = 8), at penetration of the skin by towel clips (n = 25), at skin incision (n = 20), at sternotomy (n = 20) and during multiple episodes of electrocauterization (n = 135). These provoked 52 clinical responses.(ABSTRACT TRUNCATED AT 250 WORDS)
Anesthesia, General↗
Pancreatic exocrine function after a sutureless pancreatico-jejunostomy following pancreaticoduodenectomy.
Exocrine pancreatic function was measured in 14 patients after pancreaticoduodenectomy for periampullary neoplasms in order to assess the patency of a sutureless pancreatico-enteric anastomosis. Pancreatic function was examined by the p-aminobenzoic acid/p-aminosalicylic acid (PABA/PAS) test 3-160 months after operation and compared with age- and sex-matched controls. There were no significant differences between mean (s.e.m.) serum PABA concentrations 3 h after ingestion of N-benzoyl-L-tyrosyl-PABA (25.5 (3.6)) mumol/l for patients, 26.1 (2.0) mumol/l for controls). However, the mean (s.e.m.) PABA excretion index was significantly lower in the patients (0.58 (0.08)) than in the controls (0.76 (0.04)). Four patients required pancreatic enzyme supplements for control of diarrhoea. Self-limiting pancreatic leaks occurred in two patients. The results suggests that the sutureless pancreatico-enteric anastomosis has an acceptably low leakage rate but that pancreatic exocrine function is diminished following pancreaticoduodenectomy with this technique. However, the majority of patients require no enzyme supplements and no significant tendency to late stenosis of the anastomosis was demonstrated.
4-Aminobenzoic Acid↗
The benefit of the Hemonetics cell saver apparatus during cardiac surgery.
This retrospective chart review of 155 patients having coronary artery bypass graft surgery (CABG) over a two-month period determined whether the use of a cell saver apparatus (CSA) (1) reduced or increased the requirements for homologous blood; (2) increased the incidence of post-surgical bleeding; (3) was cost-effective. Two groups of patients were identified. Group 1 (n = 99) received both CSA processed red blood cells and homologous blood components. Requirement for homologous blood products was reduced in the first 24 hr after surgery (0.5 +/- 1.0 vs 1.3 +/- 1.8 units; P less than 0.05) when compared with Group 2 (n = 56) in whom only homologous blood products were utilized. More patients in Group 1 had no transfusion requirements (45 vs 8; P less than 0.05) and there was no increased risk of major haemorrhage. When the capital costs are included, utilization of the CSA was not cost-effective. We conclude that utilisation of a CSA was safe, with no increased risk of bleeding, reduced requirements for homologous blood transfusions, but added to the cost of the procedure.
Blood Transfusion↗
Cellular and muscle zinc in surgical patients with and without gastrointestinal cancer.
1. The zinc status of surgical patients with and without gastrointestinal cancer was studied. 2. Plasma zinc was lowest in patients with cancer concurrent with depressed plasma albumin concentrations. 3. Polymorphonuclear cell zinc was decreased in both patient groups and correlated strongly with abdominal muscle zinc (r = 0.89, P less than 0.001). 4. Mononuclear cell and total leucocyte zinc were similar to control values in both groups of patients. Total leucocyte, but not mononuclear cell, zinc correlated weakly with muscle zinc (r = 0.48, P less than 0.05). 5. The results suggest that polymorphonuclear cell zinc may be better than leucocyte zinc in assessing zinc status and that some surgical patients may be zinc-depleted. The presence of gastrointestinal cancer did not influence the zinc status.
Adult↗
Periampullary diverticula predispose to primary rather than secondary stones in the common bile duct.
Periampullary duodenal diverticula are known to be associated with an increased incidence of common bile duct stones. The nature of the association with gallstones remains uncertain. We have examined the incidence of periampullary diverticula and stones after cholecystectomy to determine whether the stones originate primarily in the common duct or migrate from the gallbladder under the influence of abnormal biliary motility. Six hundred and forty-one patients undergoing ERCP were studied. Ninety-five patients had diverticula (14.8%). Diverticula occurred more commonly in jaundiced patients, 47/95, (48.4%) than in patients with normal bilirubin 185/546 (33.8%) (p less than 0.01). Common duct stones were associated with the presence of a diverticulum in 41/95 patients (43%), compared with only 98/546 without a diverticulum (18%) (p less than 0.001). There was no difference in the incidence of common duct stones in association with a diverticulum between those who had had a cholecystectomy 20/41, and those with intact gallbladders, 21/54 (N.S.). Thus the absence of a gallbladder did not alter the high incidence of common duct stones. We conclude that the stones in the common duct are most likely to be primary stones which have formed as a result of periampullary dysfunction.
Cholangiopancreatography, Endoscopic Retrograde↗