Use of alpha-agonists for management of anaphylaxis occurring under anaesthesia: case studies and review.

Anaphylaxis is an uncommon but serious complication of anaesthesia. Most current guidelines for the management of anaphylaxis list only epinephrine as a vasopressor to use in the event of cardiovascular collapse. We present two cases of anaphylaxis under anaesthesia where return of spontaneous circulation was refractory to epinephrine, but occurred following the administration of the alpha-agonist metaraminol. Potential advantages and disadvantages of using epinephrine in this setting, the role of alpha-agonists and some potential mechanisms accounting for their role in successful management are reviewed.

Use of a 'hospital-at-home' service for patient optimization before resection of phaeochromocytoma.

The perioperative management of phaeochromocytoma remains a complicated anaesthetic challenge, often requiring a prolonged preoperative hospital stay or numerous outpatient clinic visits. This is not only inconvenient for the patient, it also puts them at additional risk of acquiring hospital infections and is expensive to the health service. We present a patient with a phaeochromocytoma who was successfully managed preoperatively with phenoxybenzamine in the community by a 'hospital-at-home' service. She required no other antihypertensives before operation, although glyceryl trinitrate and magnesium sulphate were used before induction of anaesthesia. Apart from intervention for a chest infection on day 3, she had a relatively smooth hospital course and returned home on day 13. We suggest that this may be an appropriate management option for selected patients.

Contrast echocardiography improves the accuracy and reproducibility of left ventricular remodeling measurements: a prospective, randomly assigned, blinded study.

OBJECTIVES: We sought to assess the impact of contrast injection and harmonic imaging, on the measure by echocardiography of left ventricular (LV) remodeling. BACKGROUND: Left ventricular remodeling is a precursor of LV dysfunction, but the impact of contrast injection and harmonic imaging on the accuracy or reproducibility of echocardiography is unclear. METHODS: We prospectively collected LV images by using simultaneous methods. Then, LV volumes were measured off-line, in blinded manner and in random order. The accuracy of echocardiography was determined in comparison to electron beam computed tomography (EBCT) in 26 patients. The reproducibility of echocardiography was assessed by three blinded observers with different training levels in 32 patients. RESULTS: End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF), as measured by EBCT (195 +/- 55, 58 +/- 24 and 137 +/- 35 ml and 71 +/- 5%, respectively) and echocardiography with harmonic imaging and contrast injection (194 +/- 51, 55 +/- 20 and 140 +/- 35 ml and 72 +/- 4%, respectively), showed no differences (all p > 0.15) and excellent correlations (all r > 0.87). In contrast, echocardiography using harmonic imaging without contrast injection underestimated the EBCT results (all p < 0.01). Reproducibility was superior with rather than without contrast injection for intraobserver and interobserver variabilities (all p < 0.001). Values measured by different observers were different without contrast injection, but were similar with contrast injection (all p > 0.18). Consequently, intrinsic patient differences represented a larger and almost exclusive proportion of global variability with contrast injection for EDV (94 vs. 79%), ESV (93 vs. 82%), SV (87 vs. 53%) and EF (84 vs. 41%), as compared with harmonic imaging without contrast injection (all p < 0.005). CONCLUSIONS: For assessment of LV remodeling, echocardiography with harmonic imaging and contrast injection improved the accuracy and reproducibility, as compared with imaging without contrast injection. With contrast injection, variability was almost exclusively due to intrinsic patient differences. Therefore, when evaluation of LV remodeling is deemed important, assessment after contrast injection should be the preferred echocardiographic approach.

Contrast dobutamine stress echocardiography: clinical practice assessment in 300 consecutive patients.

In this study we compared non-contrast imaging with contrast imaging of the left ventricle during dobutamine stress echocardiography (DSE). Wall segment visualization, image quality, and confidence of interpretation were determined with and without the use of intravenous Optison, a second-generation echocardiographic contrast agent, in 300 consecutive patients undergoing rest and peak DSE. At rest and at peak stress, the percentage of wall segments visualized, image quality, and confidence of interpretation were better with contrast compared with non-contrast imaging. No significant decrease was seen in wall segment visualization, image quality, or confidence of interpretation from rest to peak stress in images obtained with contrast, unlike the images obtained without contrast from rest to peak stress. The use of the intravenous echocardiographic contrast agent Optison during DSE significantly improved wall segment visualization and image quality at rest and at peak stress, resulting in improved confidence of interpretation.

A rapid stress-testing protocol for the detection of coronary artery disease: comparison of two-stage transesophageal atrial pacing stress echocardiography with dobutamine stress echocardiography.

OBJECTIVES: We compared a new two-stage transesophageal atrial pacing stress echocardiography (TAPSE) protocol with a standard dobutamine stress echocardiography (DSE) protocol. BACKGROUND: Transesophageal atrial pacing stress echocardiography has been proposed as an efficient alternative to DSE. METHODS: Two-stage TAPSE (85% and 100% of age-predicted maximum heart rate) and DSE (5 to 40 microg/kg/min at 3-min stages with or without atropine) were both performed, in random sequence, in each patient of a study group of 36 patients. Regional wall-motion analysis, patient acceptance (1 = low, 5 = high), hemodynamics and duration for performing and interpreting tests were compared. RESULTS: Transesophageal atrial pacing stress echocardiography was successful in 35 of the 36 patients (feasibility 97%). More TAPSE than DSE studies were called "ischemic" (37% vs. 14%; p = 0.005). Peak heart rate was higher with TAPSE (144 +/- 18 vs. 129 +/- 15 beats/min, p = 0.0001). Peak cardiac index (4.6 +/- 2.1 vs. 5.1 +/- 1.9 liters/min/m2, p = 0.14), patient acceptance score (4.2 +/- 0.7 vs. 3.8 +/- 1.3, p = 0.17) and study duration (14.2 +/- 9.3 vs. 13.3 +/- 3.3 min, p = 0.59) were similar. Recovery time (7.1 +/- 7.6 vs. 16.2 +/- 15.9 min, p = 0.0003) and interpretation time (9.1 +/- 2.8 vs. 13.5 +/- 4.4 min, p = 0.0001) were shorter for TAPSE than for DSE. CONCLUSIONS: Two-stage TAPSE permits rapid evaluation of cardiac patients. Peak cardiac index and patient acceptance scores were similar for TAPSE and DSE. Ischemia was detected more often with TAPSE; this result was attributed to the higher peak heart rate obtained with this protocol.

Effect of various types of dietary fibre on gastric emptying in growing pigs.

1. Five pigs initially of 40-50 kg live weight were fitted with simple gastric cannulas which permitted complete evacuation and sampling of gastric digesta once daily. 2. The effects of addition of four types of dietary fibre (wheat bran (WB; 40 g/kg), sodium carboxymethylcellulose (CMC; 40 g/kg), high-methoxy citrus pectin (Pe; 40 g/kg) and granulated guar gum (G; 40 g/kg] on gastric emptying of a semi-purified diet during 4 h following a meal were measured. 3. Each of the test diets and the control diet (C) were given to each pig for 1 week using a 5 x 5 Latin-square arrangement. Digesta were collected before and 0.5, 1, 2 or 4 h after feeding on the last 5 d of each week. 4. The mean gastric pH was not significantly affected by diet except 2 h after feeding (CMC higher than C) and 4 h (Pe, G and CMC higher than C). 5. Compared with diet C, the rate of gastric emptying of digesta was significantly slower for diet G, 1, 2 and 4 h after feeding, and 2 and 4 h after feeding for diet CMC. 6. The rates of gastric emptying of digesta components were not significantly reduced by dietary fibre except for dry matter (DM) (diet CMC 2 h and diet B 4 h after feeding), total nitrogen (TN) (diet G 2 h after feeding) and total glucose (diet Pe 2 h after feeding). 7. There were no significant effects of diet on trichloroacetic-acid-soluble N:TN. 8. When gastric emptying was expressed in terms of half-time (T50) values, significant increases (compared with diet C) were found for digesta (diets G and CMC), DM (diet WB) and TN (diet G). 9. The apparent viscosity of the gastric digesta was significantly higher when diets Pe, G, and CMC were given than diets C or WB. Diets Pe and CMC were very viscous in the meal before ingestion, but diet G was not; its high viscosity developed after it had reached the stomach. 10. It is concluded that although those types of dietary fibre which increased meal or gastric viscosity reduced the rate of gastric emptying of digesta, this effect was confined to the liquid phase, because DM, total glucose and TN emptying were largely unaffected. The hypothesis that a reduced rate of gastric emptying may be an important determinant of the decreased rates of glucose absorption observed when such sources of dietary fibre are eaten is not supported by the results presented.

Effect of guar gum on gastric emptying in growing pigs.

1. Simple gastric cannulas were surgically fitted to four pigs, initially of 30 kg live weight, to examine the effects of guar gum on gastric emptying. 2. Four semi-purified high-fat diets based on starch, casein, soya-bean oil and tallow were given to each pig. They contained 0 (control), 20, 40 or 60 g powdered guar gum/kg diet. The meals as fed contained 257 g dry matter (DM)/kg. 3. The contents of the stomach were evacuated, with rinsing, before feeding or 0.5, 1, 2 or 4 h after feeding. 4. The mean pH of the digesta was unaffected by guar gum until 4 h after feeding when the value increased as the amount of guar gum in the diet rose. 5. The only significant effects of guar gum on the emptying of digesta and its components (compared with the control diet) were to reduce the rate of emptying of (a) digesta 1 h after feeding (60 g/kg diet) and 4 h after feeding (40 and 60 g/kg diets), (b) dry matter and glucose 1 h after feeding (60 g/kg diet), (c) nitrogen 1 h after feeding (60 g/kg diet) and 4 h after feeding (40 and 60 g/kg diets). 6. When expressed on a half-time (T50) basis, the emptying of digesta and N (but not of DM and glucose) were significantly slower for diets containing 40 and 60 g guar gum/kg than for the control diet. 7. The apparent viscosity of the gastric digesta ranged between 0.5 and 23.7% of the values for the diets as consumed. 8. It was concluded that the effects of guar gum on gastric emptying of high-solid meals were small, and that this was unlikely to be an important aspect of the mechanism by which guar gum reduces postprandial blood glucose concentrations.

Effect of guar gum on gastric emptying of test meals of varying energy content in growing pigs.

1. Existing information on whether the action of guar gum in decreasing postprandial blood glucose concentrations is due, at least in part, to a reduced rate of gastric emptying is conflicting, possibly because three types of test meals have been used. In order to test whether the type of test meal used influences the action of guar gum, these three types of meal were compared, either without or with guar gum, in growing pigs. The meals were: a high-energy meal (HEM), a low-energy milky drink (LEMD) and a glucose drink (GD). 2. Six pigs were prepared with a simple gastric cannula which allowed complete removal of the stomach contents just before or 0.5, 1, 2 or 4 h after feeding. 3. The three types of test meal without guar gum gave rise to very different postprandial profiles of gastric pH and of digesta and dry matter (DM) emptying from the stomach. 4. Addition of guar gum to the GD significantly raised gastric pH at 0.5 and 1 h after feeding but, when it was added to HEM, gastric pH was only significantly raised 4 h after feeding. No significant effect on gastric pH was seen when guar gum was added to LEMD. 5. Although addition of guar gum to GD had no significant effect on the emptying of digesta from the stomach, when added to HEM the rate of emptying of digesta was significantly reduced 1, 2 and 4 h after feeding. Addition of guar gum to LEMD only significantly increased the amount of digesta remaining in the stomach 2 h after feeding. 6. There was no significant effect on the emptying of DM from the stomach when guar gum was added to either HEM or LEMD. However, addition of guar gum to GD significantly reduced the mean rate of emptying of DM 0.5 h after feeding. 7. Addition of guar gum to either LEMD or GD had no significant effect on the DM concentration of the evacuated gastric digesta. However, addition of guar gum to HEM significantly lowered the DM concentration of the evacuated gastric digesta 1, 2 and 4 h after feeding. 8. It was concluded that differences in test meal composition and also in the methods used to measure gastric emptying could account for the discrepancies previously reported. The results suggest that although guar gum may reduce the rate of gastric emptying under some conditions, this is unlikely to be the only mechanism by which it acts.

The effect of guar gum and level and source of dietary fat on glucose tolerance in growing pigs.

Six growing pigs (30-75 kg) were fed on semi-purified diets containing either 30 g maize oil/kg diet (LFM), 30 g soya-bean oil-tallow mixture (1:1, w/w)/kg diet (LFST) or 160 g soya-bean oil-tallow mixture (1:1, w/w)/kg diet (HFST) without and with the addition of guar gum (40 g/kg diet). Plasma glucose and insulin concentrations following twice daily feeding at 09.00 and 21.00 h were measured, during 24 h periods, in blood sampled from a permanent indwelling vena cava catheter. The source and level of dietary fat had no significant effect on pre-prandial plasma glucose or insulin concentrations except for insulin with diet LFST in the morning (P less than 0.05). Addition of guar gum to the diets had no significant effect on pre-prandial plasma glucose and insulin levels. The peak post-prandial plasma glucose and insulin levels were not significantly affected by dietary fat. The addition of guar gum, however, significantly reduced (P less than 0.05) the peak post-prandial plasma glucose concentration with diets LFM and LFST and also the peak plasma insulin concentration for all diets except for diet HFST in the morning. The time taken to reach the peak post-prandial plasma glucose and insulin concentrations was not significantly affected by dietary fat but it was increased by the addition of guar gum, although the differences were not always significant.

Effect of guar gum on glucose and water absorption from isolated loops of jejunum in conscious growing pigs.

Four pigs initially of 30 kg live weight were surgically prepared with two re-entrant cannulas in the jejunum 1.0 m apart which allowed an isolated loop to be formed through which solutions were perfused. 51Cr-EDTA was used as a marker for measuring net secretion or absorption. A new Ringer solution was made, the ionic content of which resembled more closely that found in the jejunum of pigs given similar diets, than Krebs-Ringer solution. The absorption of glucose and water from Krebs-Ringer and new Ringer solutions was compared. The effect of guar gum on the absorption of glucose and water from solutions of glucose and maltose was studied. There was a trend (not significant) for greater absorption of glucose and water from the new Ringer solution than from the Krebs-Ringer solution. Guar gum significantly reduced the net absorption of glucose from glucose or maltose solutions from 74.2 to 41.4% (P less than 0.001) and 71.1 to 35.0% (P less than 0.001) respectively. Guar gum significantly reduced the net absorption of water from the glucose solution from 42.7 to 8.3% (P less than 0.01) and from the maltose solution from 49.2 to 5.1% (P less than 0.001). The lack of differences between the absorption of glucose from solutions of glucose or maltose suggested that maltase (EC 3.2.1.20) activity was not inhibited to the extent that this limited the rate of glucose absorption.

Effect of guar gum on nitrogen secretion into isolated loops of jejunum in conscious growing pigs.

Four pigs, initially of 30 kg live weight, were surgically prepared with two re-entrant cannulas in the jejunum, 1.0 m apart. This allowed an isolated loop to be formed through which Ringer solutions were continuously perfused for 6.5-h periods per day. The effects of two Ringer solutions of contrasting composition on nitrogen secretion were measured in a preliminary study. The effects of guar gum (6.7 g/l) on N secretion during perfusions of solutions of glucose or of maltose (20 g/l) were measured. N secretion did not differ significantly between the two Ringer solutions. Addition of guar gum to the solution of glucose increased mean N secretion from 69.2 to 133.9 mg/m per 2 h; the corresponding values for the maltose solution were 75.5 and 120.2 mg/m per 2 h. In both cases the differences were significant (P less than 0.001). Differences between N secretion into glucose and maltose solutions were not significant, either without or with guar gum. Guar gum addition had a greater effect on N secretion in hours 5 and 6 than in hours 1 and 2 of perfusion. It was calculated that guar gum would have increased N section by the mucosa of the whole small intestine from approximately 15 to 27 g/d under the conditions of the study, assuming uniform secretion throughout the organ. These results suggest that certain types of dietary fibre may be important determinants of N secretion by the mucosa of the small intestine. They also suggest that changes in N secretion of this magnitude are of importance in N metabolism because the overall rate of protein synthesis in these pigs was probably about 100 g/d (expressed as N), using values from the literature.

Restricted spread of analgesia following epidural blood patch. Case report with a review of possible complications.

A complete restriction of upward spread of local analgesic solution in the epidural space is reported in a patient who three years earlier had received an epidural blood patch for post-spinal headache. Organisation of the blood clot with fibrous tethering of the dura to the wall of the spinal canal is suggested as the most likely cause of this apparent obstruction to spread. Other potential complications of epidural blood patch are presented. It is concluded from the literature on the subject that there is a need for a multi-centre analysis of the factors which might influence the incidence of inadvertent dural tap with an epidural needle.