Baseline oxygen delivery is associated with an increased risk of severe postoperative complications after elective open repair of abdominal aortic aneurysm.

AIM: Oxyhemodynamic parameters have been shown to have a relevant impact on the immediate postoperative outcome after major surgery, but it is not known their specific impact on the outcome after elective repair of abdominal aortic aneurysm (AAA). METHODS: One-hundred and forty-one patients underwent elective open repair of infrarenal AAA and hemodynamic parameters were monitored perioperatively. RESULTS: One patient (0.7%) died postoperatively, 23 (16.3%) experienced a myocardial ischemic event and 9 of them (6.4%) had a myocardial infarction. Baseline oxygen delivery was not predictive of such myocardial ischemic events. Thirty-three patients (23.4%) suffered severe postoperative complications. The median baseline oxygen delivery was 429.5 mL/min/m2 among patients who had severe postoperative complications, whereas it was 505.5 mL/min/m2 among those who did not have severe complications (p=0.03). However, this parameter did not retain its significance at multivariate analysis. When only the preoperative variables were included in the logistic regression model, the Glasgow Aneurysm Score (P=0.004, Oddsratio 1.94, 95% C.I. 1.24-3.05) was the only predictor of severe postoperative complications. The Glasgow Aneurysm Score was significantly correlated with baseline oxygen delivery (P=-0.256, P=0.003). CONCLUSIONS: Baseline oxygen delivery is associated with an increased risk of severe postoperative complications after elective open repair of AAA. The value of preoperative optimization of oxygen delivery should be evaluated in this patient population.

Atrial plasma ANP and NH2-terminal proANP during right atrial pressure increase in humans.

To compare plasma NT-proANP, a stable and biologically inactive N-terminal portion of ANP prohormone, with the known plasma ANP response to increased right atrial pressure a Swan-Ganz catheter was inserted into the right atrium of five normal healthy male volunteers. The elevation of right atrial pressure was produced by a head-down tilt after a hypertonic saline infusion. Blood samples were drawn from the lumen of the right atrium. After 5 min of starting the tilt the right atrial pressure had increased from 7.0 +/- 1.0 to 11.6 +/- 0.9 mmHg (P < 0.05) and then began to normalize in spite of the constant tile. Atrial plasma ANP increased in relation to the pressure increase and peaked at 15 min after the start of the tilt. The change was from 27.9 +/- 6.5 to 53.9 +/- 9.7 pmol L-1 (P < 0.05). Atrial plasma NT-proANP increased significantly from 357 +/- 91.2 to 529.1 +/- 116.0 pmol L-1 (P < 0.05) at 10 min and remained high throughout the experiment. The molar ratio of NT-proANP to ANP varied in atrial plasma from 9.5 +/- 1.2 to 13.9 +/- 2.7 showing that the plasma clearance of ANP from plasma was much higher than that of NT-proANP.

Mouth-rinsing with chlorhexidine causes a delayed, temporary increase in the levels of oral viridans streptococci.

The indigenous oral flora of 27 volunteers was monitored longitudinally over a 4-week period. Bacteria attached on buccal epithelial cells were counted by microscopy. Salivary bacterial colonies and the presence of alpha-hemolysis were examined after aerobic culturing on blood agar plates. The buccal and salivary bacterial counts were stably maintained in most subjects in the two repeated base-line samplings taken at 1-week intervals. Rinsing with a chlorhexidine mouthwash 45 min before sampling dramatically reduced the amount of epithelial cell-adherent bacteria. One day after the chlorhexidine rinse, however, the numbers of the epithelial cell-adherent bacteria exceeded the base-line level, and a similar decrease-increase pattern of changes was detected for the salivary alpha-hemolytic streptococcal counts. The non-hemolytic salivary bacterial counts were not affected by chlorhexidine. Subsequent weekly samplings showed no difference from the base-line samplings. The chlorhexidine-induced, delayed increase of viridans streptococci on oral epithelial surfaces should be considered a possible risk factor in medically compromised patients.

Magnesium substitution in elective coronary artery surgery: a double-blind clinical study.

Magnesium may be beneficial in the control of ventricular ectopy and supraventricular tachyarrhythmias after coronary artery bypass graft (CABG) surgery, but it is not known whether a high-dose magnesium regimen is superior to a regimen keeping the patient normomagnesemic. A prospective randomized and double-blind clinical comparison was performed in 81 elective CABG patients in order to assess the effects of two different magnesium infusion regimens on electrolyte balance and postoperative arrhythmias. Forty-one patients (high-dose group, H) received 4.2 +/- 0.7 g (mean +/- SD), of magnesium sulfate before cardiopulmonary bypass, followed by an infusion of 11.9 +/- 2.8 g of magnesium chloride until the first postoperative (PO) morning, and a further 5.5 +/- 1.0 g until the second PO morning. Forty patients (low-dose group, L) received magnesium sulfate only after bypass to a total of 2.9 +/- 0.5 g at the first, and 1.4 +/- 0.1 g at the second PO morning. A blood cardioplegia technique was used in both groups, including bolus doses of magnesium chloride to a total of 2.4 +/- 0.6 g and 2.3 +/- 0.6 g to H and L patients, respectively. Continuous Holter tape-recording was used for 12 to 15 hours preoperatively, and for 48 hours postoperatively. Serum magnesium peaked in H patients on the first PO morning at 1.60 +/- 0.25 mmol/L, whereafter it declined to the normal level on the third PO morning. Patients in the L group were normomagnesemic, except after the start of bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino acid-enriched glucose-insulin-potassium infusion improves hemodynamic function after coronary bypass surgery. A double-blind study in patients with unstable angina and/or compromised left ventricular function.

OBJECTIVE: The goal of this study was to assess the effects of a combination of glucose-insulin-potassium (GIK) and the amino acids aspartate and glutamate upon perioperative hemodynamics in coronary surgery patients with unstable angina and/or compromised left ventricular function. DESIGN: Prospective, randomized, and double-blind clinical study. SETTING: Operating theatre and intensive care unit (ICU) of a university hospital. PATIENTS: 44 coronary artery bypass graft (CABG) patients with unstable angina and/or compromised left ventricular function. INTERVENTIONS: 22 patients (group A) were given 1l of an infusion with 250g glucose, 100 I.U. fast-acting human insulin, 72 mmol potassium, 32 mmol magnesium, 20 mmol phosphate, 65 mmol aspartate, and 65 mmol glutamate, while another 22 patients (group C) were given 1l of an infusion with 50 g glucose, 72 mmol potassium, 32 mmol magnesium, and 8 mmol phosphate. The infusion rate was 1.2 ml/kg/h from the anesthesia induction onward to the commencement of cardiopulmonary bypass, when it was reduced to 0.8 ml/kg/h. When 11 had been infused, but not later than 4 a.m., the infusion was continued by giving 10% glucose at the same rate to both groups. Additional insulin (median: 14.2 I.U., range: 0-41.5) or saline was given during bypass to the A and C patients, respectively. A blood cardioplegia technique containing aspartate and glutamate was used in both groups. RESULTS: At aortic cannulation, the cardiac index (CI) had increased from the pre-anesthetic level by 15.3% (mean) (SD: 31.7%) in group A and decreased by 7.7% (15.1%) in C patients, p = 0.0069. Also the changes in stroke index (SI; p = 0.022), left (LVSWI; p = 0.0037) and right ventricular stroke work index (RVSWI; p = 0.0097) were more favorable in group A. Despite longer aortic cross-clamp, p = 0.031, and perfusion times, p = 0.042, in A patients, the change in cardiac index was also better in this group after bypass: At decannulation, the difference between mean values was 31.8%, p = 0.0001, and at arrival in the ICU it was 16.1%, p = 0.028. The same was also seen 8 h postoperatively and on the 1st and 2nd postoperative mornings; p = 0.034, 0.040, and 0.037, respectively (Wilcoxon test). Favorable changes were seen for the A patients also regarding SI at decannulation (p = 0.0002) and after 8 h (p = 0.017); LVSWI at decannulation (p = 0.0002), at arrival in the ICU (p = 0.0023), and after 8 h (p = 0.0011); and RVSWI at decannulation (p = 0.0027), at the ICU (p = 0.021), after 8 h (p = 0.014), and on the 1st postoperative morning (p = 0.039). However, the response to a hemodynamic loading test (6% hydroxyethyl starch 5 ml/kg) was similar in the 2 groups, and there was no difference in the need for inotropic support. CONCLUSIONS: Amino acid-enriched GIK infusion improves hemodynamic function in CABG patients with unstable angina and/or compromised left ventricular function.

Perioperative glucose-insulin-potassium infusion in elective coronary surgery: minor benefit in connection with blood cardioplegia?

OBJECTIVE: The goal of this study was to examine the metabolic and hemodynamic effects of a glucose-insulin-potassium infusion in elective coronary surgery, when blood cardioplegia was used for cardiac protection. DESIGN AND PATIENTS: A prospective, randomized, open, clinical comparison was performed between 2 perioperative infusion regimens in 40 elective nondiabetic coronary artery bypass graft (CABG) surgery patients. SETTING AND INTERVENTIONS: 20 patients (glucose-insulin-potassium-GIK-group) received glucose 0.2 g/kg/h, insulin 0.12 U/kg/h, potassium 0.15, magnesium 0.032 and phosphate 0.024 mmol/kg/h from anesthesia induction to the start of bypass, when infusion rate was reduced to 30%, and after bypass increased to 50% of the initial rate. The infusion was continued until the first postoperative morning. Another 20 patients (control-R-group) received glucose 0.05 g/kg/h, potassium 0.075, magnesium 0.016 and phosphate 0.008 mmol/kg/h from the end of bypass to the next morning. Pump prime was glucose-free and a blood cardioplegia technique was used for cardiac protection. RESULTS: The GIK patients needed less dopamine support in the intensive care unit (ICU) (p < 0.05). No difference was found between the groups with regard to myocardial injury, the MB-fractions of serum creatine kinase (CK-MB) being elevated to a similar degree in both groups. Likewise there were no significant differences in hemodynamic changes or duration of ICU stay. Although the glucose infusion was continued during bypass in the GIK patients, there was a considerable risk of hypoglycemia (due to insulin and hemodilution) after the onset of bypass: in 5 GIK patients (25%; 95% confidence interval 8.7 to 49.1%) blood glucose was less than 2 mmol/l. However, the hypoglycemia was of short duration and no detrimental effects were seen. CONCLUSIONS: Perioperative GIK infusion entailed a slight decrease in the postoperative need for dopamine support, but was connected with a considerable risk of hypoglycemia.

Efflux of adenosine and its catabolites during cold blood cardioplegia.

Levels of myocardial high-energy phosphates decrease during cardioplegia for open heart operations, with a subsequent increase in the level of adenosine and its metabolites. It has been demonstrated in experimental models that the effluent concentrations of purines can be used as a measure of the average myocardial energy state. Net adenylate loss and myocardial energy state were evaluated here by determining aorta-coronary sinus differences in levels of adenosine catabolites in 17 patients during cold blood cardioplegia for elective coronary artery bypass grafting. Repeated blood samples were taken before cross-clamping of the aorta, when cardioplegic solute was infused into the aortic root and grafts after five distal anastomoses, and after declamping of the aorta. The aorta-coronary sinus differences in levels of total purines increased 4.7-, 7.5-, 7.1-, 7.8-, and 10.2-fold (from the preclamp level of 1.7 +/- 0.7 mumol/L; p < 0.001) for grafts one through five anastomosed at an average of 19, 34, 50, 63, and 76 minutes after the aortic cross-clamp, respectively. Hypoxanthine and xanthine were present in the highest concentrations. Vasodilatory adenosine concentrations of 1 to 2 mumol/L were observed in the coronary sinus while the aorta was cross-clamped. There was a linear positive correlation between the aorta-coronary sinus purine differences and corresponding cross-clamp time (r = 0.62; p < 0.001). The metabolite differences settled at a more negative level after declamping of the aorta than that prevailing before placement of the cross-clamp, suggesting continuous washout of adenosine and its catabolites during the 30-minute postclamp observation period.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma ANP during hypertonic NaCl infusion in man.

To determine the relationship between hyperosmolality and immunoreactive atrial natriuretic peptide of heart atrial plasma six healthy men were given 0.06 ml kg-1 min-1 855 mmol l-1 NaCl, i.v., for 2 h. The right atrial pressure and atrial plasma atrial natriuretic peptide were measured. During the infusion, right atrial pressure was kept constant by lowering the legs of the subject in a supine position downwards if any increase in the pressure was seen. There was a significant and linear increase in atrial serum osmolality, from 288 +/- 3.3 to 307 +/- 3.2 mOsm kg-1 (P less than 0.001). No statistically significant changes in right atrial pressure were seen. Regression analysis revealed that there was a statistically significant correlation between serum osmolality and plasma ANP in three subjects (responders) (r2: 0.5241, 0.8965, 0.6695). In three other subjects (nonresponders), there was no correlation between osmolality and ANP. The mean basal osmolality of responders was 280 mOsm kg-1 and the mean basal osmolality of nonresponders was 295 mOsm kg-1. In contrast, all subjects responded with an increase in plasma ANP (P less than 0.05) after RAP had been increased by tilting the legs of the subject upwards for 30 min. We conclude that the right atrial pressure regulates the release of atrial natriuretic peptide. Serum hyperosmolality may also contribute to the regulation of atrial natriuretic peptide independently of the right atrial pressure in man.

Maternal and umbilical venous plasma immunoreactive beta-endorphin levels during labor with and without epidural analgesia.

Maternal and umbilical venous plasma immunoreactive beta-lipotropin/beta-endorphin levels were determined during labor in 23 healthy parturient women at term. Eleven of the mothers received a segmental epidural analgesic for relief of pain, whereas the other 12 mothers were nearly pain-free and needed no analgesia. Maternal immunoreactive beta-lipotropin/beta-endorphin levels were already significantly elevated at the beginning of labor in both groups in comparison with nonpregnant young women. Maximum levels of immunoreactive beta-lipotropin/beta-endorphin were reached at delivery, and these mean levels were significantly higher than the initial mean levels in the epidural group (p less than 0.05) and in the control group (p less than 0.001). There were statistically no significant differences between the groups at any time. The umbilical venous plasma immunoreactive beta-lipotropin/beta-endorphin levels did not differ from each other in the epidural and the control groups. These results suggest that the stress of labor causes an increase in the maternal secretion of immunoreactive beta-lipotropin/beta-endorphin which is not related to the degree of pain itself. Epidural analgesia has also no effect on umbilical venous plasma immunoreactive beta-lipotropin/beta-endorphin.