[Control of postoperative pain in heart surgery. Comparison of analgesics]. / Il controllo del dolore postoperatorio in cardiochirurgia. Analgesici a confronto.

BACKGROUND: Evaluation of the efficacy of three analgesic drugs (tramadol, ketorolac, and morphine) for the control of postoperative pain in cardiac surgery. DESIGN: prospective randomized study. SETTING: University Hospital, Postoperative intensive care unit. PARTICIPANTS AND INTERVENTION: sixty patients, who underwent cardiac surgery, were studied. They were randomly allocated in four groups, treated with a different postoperative analgesic therapy: A) tramadol in continuous infusion; B) ketorolac in continuous infusion; C) tramadol, in repeated boluses; D) morphine, in repeated boluses. MEASUREMENTS: the analgesic efficacy of each drug and administration protocol was evaluated by hemodynamic stability, arterial blood gases analysis, Visual Analogue Scale (VAS), resting and after cough, the VAS derivatives PID and SPID, the concentration of plasma epinephrine and norepinephrine, at eight postoperative times. Adverse effects were also registered. RESULTS: Only tramadol, in continuous i.v. infusion, achieves the required analgesic effect, significantly decreasing both VAS scores, at the end of the administration of the drug. This treatment reduced epinephrine plasma levels in the first postoperative day, when the residual analgesic effect of surgical anesthesia can be considered disappeared. CONCLUSIONS: Tramadol in continuous infusion (dose 12 mg/h) proved to be effective for the control of postoperative pain after cardiac surgery. The proposed dose represents a good compromise between analgesic efficacy and interference with the vital functions of operated patients.

Patent side branches do not affect coronary blood flow in internal thoracic artery-left anterior descending anastomosis: an experimental study.

BACKGROUND: It has been reported that large side branches of internal thoracic artery grafts may steal flow from the coronary circulation. Material an. METHODS: To assess the importance of the side branches, we measured the proximal and distal flow and pressures (mean subclavian artery pressure and mean arterial anastomotic pressure) at baseline and during infusion of adenosine (0.5 mg/kg/min) in 10 Landrace pigs in which an internal thoracic artery-left anterior descending anastomosis was constructed without interruption of the side branches. The difference between proximal and distal flow was considered to represent the blood flow of the internal thoracic artery side branches. Measurements were then repeated after surgical occlusion of all the side branches. RESULTS: At baseline, blood flow of the side branches represented 18% of the total flow in the proximal internal thoracic artery, and this percentage remained constant under the infusion of adenosine, which caused a 220% increase of the cardiac index and a 368% increase of the proximal flow. The infusion reduced the gradient along the left internal thoracic artery (mean subclavian artery pressure-mean arterial anastomotic pressure) from 15 to 10 mm Hg (P =.02) as the result of a lower mean subclavian artery pressure, although the mean arterial anastomotic pressure remained constant. Interruption of all the side branches resulted in a small and not significant increase in distal flow even after adenosine infusion. CONCLUSION: These observations suggest that blood flow in the side branches is minimal either at baseline and under combined systemic and coronary vasodilation. Clinically significant flow steal from the coronary circulation to the internal thoracic artery side branches seems then unlikely.

Time dependence of endothelium-mediated vasodilation by intermittent antegrade warm blood cardioplegia.

BACKGROUND: The technique of intermittent antegrade warm blood cardioplegia (IAWBC) exposes the heart to brief periods of normothermic ischemia. This may impair endothelial function in coronary arteries. METHODS: Three cardioplegic technique were tested in porcine hearts arrested for 32 to 36 minutes and reperfused for 30 minutes: IAWBC, antegrade cold blood cardioplegia (ACBC), and antegrade cold crystalloid cardioplegia (ACCC). In the hearts arrested with IAWBC, three different intervals of ischemia were used: three 10-minute intervals (IAWBC1), two 15-minute intervals (IAWBC2), and one 30-minute interval (IAWBC3). Rings from the coronary arteries were used to evaluate in vitro the contractile responses to U46619 and the relaxant responses to bradykinin, A23187, and sodium nitroprusside. RESULTS: All six groups (treatment groups and control group) displayed similar responses to U46619 (30 nmol/L) and nitroprusside. In the IAWBC1, IAWBC2, AND ACBC groups, endothelium-dependent relaxations to bradykinin and A23187 were preserved compared with controls, whereas those of the ACCC and IAWBC3 groups were significantly impaired (bradykinin: control, 8.72 +/- 0.07; IAWBC1, 8.73 +/- 0.03; IAWBC2, 8.65 +/- 0.05; IAWBC3, 8.30 +/- 0.07 [p < 0.05]; ACBC, 8.50 +/- 0.03; ACCC, 8.25 +/- 0.09 [p < 0.05]; A23187: control, 7.07 +/- 0.08; IAWBC1, 7.07 +/- 0.06; IAWBC2, 7.04 +/- 0.03; IAWBC3, 6.64 +/- 0.01 [p < 0.05]; ACBC, 6.80 +/- 0.05; ACCC, 6.60 +/- 0.08 [p < 0.05]; nitroprusside: control, 6.19 +/- 0.1; IAWBC1, 6.19 +/- 0.07; IAWBC2, 6.03 +/- 0.03; IAWBC3, 6.08 +/- 0.05; ACBC, 6.04 +/- 0.2; ACCC, 6.05 +/- 0.03; all values are expressed as the negative logarithm of the concentration producing 50% of the maximal response). CONCLUSIONS: Myocardial preservation with IAWBC with ischemic intervals of 15 minutes or shorter does not alter the endothelium-dependent relaxation to bradykinin or A23187 in porcine coronary arteries, but these responses are significantly impaired by ACCC and IAWBC with an ischemic interval of 30 minutes.

Effects of acute and prolonged administration of propafenone on internal defibrillation in the pig.

Some antiarrhythmic sodium channel blocking drugs have been found to increase the energy necessary for internal defibrillation. Propafenone is a new drug that has been shown to be efficacious in the therapy of supraventricular and ventricular arrhythmias, and is of potential use in patients with defibrillators. The effects of short-term and prolonged propafenone administration on the internal defibrillation threshold (DFT) were determined in 43 pigs randomized to one of four groups: saline infusion (n = 10); propafenone infusion (n = 10); placebo administration for 8 days (n = 10); or propafenone administration for 8 days (n = 13). Two mesh electrodes were sutured on the right lateral and left lateral epicardial surface and current was delivered from the right electrode to the left electrode. Triplicate DFTs were obtained before and at 40 and 80 minutes after infusion of drug or placebo. In pigs receiving long-term administration, after baseline DFTs were obtained the electrodes were removed and the chest was closed. Following 8 days of drug or placebo administration, DFTs were redetermined. No changes were observed in the short- or long-term control groups. DFTs were lower after propafenone administration: either short-term infusion (20 +/- 6.2 joules at baseline; 15.6 +/- 5 joules at 40 minutes, p less than 0.05; 10.2 +/- 6 joules at 80 minutes, p less than 0.001) or long-term administration (17.8 +/- 2.6 joules at baseline versus 12 +/- 3.2 joules on drug, p less than 0.002). Decreased ventricular cycle lengths were found with acute administration of propafenone. Three pigs died during long-term administration of propafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison between two versus three patches single pulse shock defibrillation in pigs.

The aim of the study was to test the hypothesis that defibrillation with a single pulse shock can be obtained at lower energy using three epicardial patches configuration (one cathode and two anodes) instead of the conventional two patches. The total surface area of the two- and three-patches configuration was the same (10 cm2 vs 9.9 cm2). Epicardial spatial configuration was planned by using a computerized heart model. In ten anesthetized open-chest pigs, ventricular fibrillation was induced by using AC current through the mesh plaque epicardial custom-designed electrodes, and the minimum energy requirement for defibrillation was determined 15 seconds after the onset of stable ventricular fibrillation. Results were as follows (mean +/- standard deviation): Defibrillation Threshold 16 +/- 9 J 9 +/- 5 J P less than 0.01 CONCLUSIONS: three epicardial patches configuration significantly reduces energy requirements for defibrillation compared with two patches when single pulse shock is used.

Intravenous propafenone reduces energy requirements for defibrillation in pigs.

The effect of antiarrhythmic drugs on defibrillation threshold have become an important issue with the increasing use of the automatic implantable cardioverter defibrillator (AICD). In several reports antiarrhythmic therapy has been found to affect the energy required for defibrillation; the present study examined the effects of intravenous propafenone on defibrillation threshold in open chest, anesthetized pigs. Twenty health pigs were studied; 10 pigs free from any drugs (Group 1) and 10 pigs after a constant iv infusion of 0.04 mg/kg/min of propafenone (Group 2). Defibrillation threshold was 21 +/- 5, 20 +/- 5, 21 +/- 6, 19 +/- 4 and 19 +/- 6 J in Group 1 and 20 +/- 7, 18 +/- 9, 15 +/- 5, 14 +/- 7, 9 +/- 6 J in Group 2, respectively at 20, 40, 60, 80 min (p value respectively NS, NS, less than 0.05, less than 0.01, less than 0.001). We conclude that intravenous propafenone reduces the energy requirements for defibrillation in experimental animals.

[A bladder tube construction using a stapler with absorbable stitches (Poly CS-57)]. / Tubulizzazione vescicale con suturatrice a punti riassorbibili (Poly CS-57).

A new technique for the construction of a bladder tube, using a Poly CS-57 stapler, has been tested on six pigs. With this procedure the operative time is shortened without complications. In fact, no crystal formation, dehiscence or infection was observed during a 3 month follow-up.