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Biomedical subjects

M Hynynen

Publications and source records attributed to M Hynynen.

At least 55 records · Page 3Linked to original sources
PubMed1993

Anaesthesia affects plasma concentrations of vasopressin, von Willebrand factor and coagulation factor VIII in cardiac surgical patients.

Operative stress may affect haemostatic mechanisms through hormonal systems. As the endocrine stress response to surgery may be modulated by anaesthesia, we have altered stress hormone concentrations by using either opioid or inhalation based anaesthesia to study haemostatic mechanisms in cardiac surgical patients. Thirty patients undergoing coronary artery surgery were allocated randomly to receive fentanyl (non-stress group) or enflurane (stress group) as the main anaesthetic agent. After cardiopulmonary bypass (CPB), plasma arginine vasopressin (AVP) concentrations were significantly (P < 0.001) greater in the stress group (81.8 (46.9-142.9) pg ml-1, mean with 95% confidence limits) than in the non-stress group (5.8 (3.3-10.2) pg ml-1). Plasma noradrenaline and adrenaline concentrations increased similarly in both groups after CPB. Plasma concentrations of both von Willebrand factor (stress: 1.56 (1.33-1.79) IU ml-1; non-stress: 1.00 (0.76-1.25) IU ml-1) and coagulation factor VIII: C (stress 1.15 (0.87-1.44) IU ml-1; non-stress: 0.69 (0.55-0.80) IU ml-1) were significantly (P < 0.01) greater in the stress group than in the non-stress group after CPB. The results indicate that there is a temporal relationship between the increased plasma concentrations of AVP and von Willebrand factor and factor VIII: C. It is not clear if this indicates a causal relationship. However, variable stress control by anaesthesia may modify haemostasis in cardiac surgical patients.

Adult↗
PubMed1993

Pulmonary vascular effects of trinitroglycerin and isosorbide dinitrate after cardiopulmonary bypass.

We have compared the systemic and right ventricular haemodynamic effects of trinitroglycerin (TNG) and isosorbide dinitrate (ISDN) in patients recovering from coronary artery bypass grafting. Each of the 16 patients was given increasing i.v. doses of the two nitrates in a random order and double blind fashion until the target of a 25% decrease in mean pulmonary artery pressure (MPAP) was achieved. Total doses of TNG 9 (6-12) micrograms kg-1 (mean, 95% confidence interval) and ISDN 148 (76-220) micrograms kg-1 were given during infusions of 22 (18-25) min and 34 (28-41) min duration, respectively. The target decrease in MPAP was produced with infusion rates of TNG 0.5 (0.4-0.7) micrograms kg-1 min-1 and ISDN 5.8 (4.1-7.5) micrograms kg-1 min-1. These doses produced similar acute decreases in MPAP and similar effects on pulmonary and systemic vascular resistances and systemic and right ventricular haemodynamic variables. We conclude that TNG is more than 10 times as potent as ISDN in its acute haemodynamic effects in cardiac surgical patients in the immediate postoperative period. Both nitrates have relatively greater effects on the pulmonary than the systemic vasculature.

Adult↗
PubMed1993

Hydroxyethyl starch as a prime for cardiopulmonary bypass: effects of two different solutions on haemostasis.

Hydroxyethyl starch (HES) is efficacious as a volume expander in cardiac surgical patients, but it may impair the haemostatic mechanisms. However, this latter effect may be less conspicuous with low molecular weight (LMW) solutions than with high molecular weight (HMW) solutions. Therefore, LMW- and HMW-HES solutions were evaluated as priming solutions for cardiopulmonary bypass (CPB) with respect to their effect on haemostasis. Forty-five patients undergoing coronary bypass grafting were prospectively randomised to three groups and received in a double-blind manner as their CPB prime either 20 ml.kg-1 LMW-HES (Mw 120,000), 20 ml.kg-1 HMW-HES (Mw 400,000) or Ringer's acetate 2000 ml. The final volume of the prime was completed to 2000 ml with Ringer's acetate in the HES groups. Anaesthesia and CPB management were standardised. Plasma levels of von Willebrand factor antigen and factor VIII procoagulant activity were significantly more depressed after CPB in both HES-groups as compared with the crystalloid prime group. In addition, APTT was more prolonged and the maximal amplitude of thromboelastographic tracing was more decreased in the HES-groups. It is concluded that it may be advisable to avoid HES solutions in the CPB prime, especially in patients with an increased risk for bleeding after cardiac operations.

Cardiopulmonary Bypass↗
PubMed1992

Pharmacokinetics and effects of atrial natriuretic factor during hypothermic cardiopulmonary bypass.

The pharmacokinetics of a bolus dose of synthetic atrial natriuretic factor (ANF) 50 micrograms and its effects on urine output, blood pressure and plasma renin activity have been studied in 5 patients undergoing hypothermic cardiopulmonary bypass for cardiac surgery. The half-lives of the fast and slow components were 2.4 min and 14.2 min, respectively. The volume of the central compartment was 16.7 l and the volume of distribution at steady-state was 38.9 l. The total plasma clearance was 3.8 l.min-1. ANF significantly increased urine output and decreased blood pressure, but it did not affect plasma renin activity.

Atrial Natriuretic Factor↗
PubMed1992

Vasodilator properties of nitroglycerin and isosorbide dinitrate during cardiopulmonary bypass.

In a placebo-controlled trial, we have studied the vasodilator properties of bolus doses of nitroglycerin (TNG) and isosorbide dinitrate (ISDN) in 32 patients during cardiopulmonary bypass with a constant pump flow. Blood volume of the venous reservoir and mean arterial pressure were recorded for 10 min after drug administration to detect changes in venous capacitance and arteriolar resistance, respectively. The venous capacitance-increasing effects of TNG 200 micrograms and ISDN 1,600 micrograms were initially identical and significant at 2 and 3 min after the bolus. Thereafter, the effect of TNG began to decline, while that of ISDN remained significant until the end of the study. TNG 200 micrograms decreased arterial pressure slightly more than ISDN 1,600 micrograms, but the effect of both drugs lasted for only 1-2 min. TNG and ISDN were equipotent in increasing venous capacitance when administered in a bolus dose ratio of 1:8 during CPB, but the venodilator effect of ISDN lasted longer than that of TNG. The duration of the arteriolar dilator effect was very short with both drugs.

Adult↗
PubMed1992

Plasma atrial natriuretic factor during ethanol ingestion in volume-loaded subjects.

The present study was designed to test whether ethanol ingestion affects plasma atrial natriuretic factor (ANF) concentration in healthy volunteers. On the basis of previous studies showing that ethanol induces a diuretic response and a decrease in atrial size (atrial distension), it was hypothesized that ethanol intake might be associated with a decrease in plasma ANF level. To somewhat increase plasma ANF level, the subjects were slightly loaded with water before the trial. As compared with juice, ethanol, 1 g/kg within 1 hr, increased urine output [405 +/- 37 (mean +/- SEM) ml/hr vs. 197 +/- 20 ml/hr, P less than 0.001]. Left atrial size decreased similarly (P less than 0.001) with both drinks. Plasma ANF concentration did not change with either ethanol or juice during the 3-hr study period. No changes were observed in plasma arginine vasopressin concentration and plasma renin activity. Our results are in conflict with previous reports in fasted subjects showing significant changes in plasma concentrations of the same hormones. Thus, the basal fluid balance seems to be crucial to the hormonal response to ethanol. The plasma concentrations of the hormones measured in this study do not directly explain the diuretic response to ethanol observed in slightly volume-loaded subjects.

Adult↗
PubMed1991

Hemodynamic responses to desmopressin acetate after CABG: a double-blind trial.

Despite controversial results concerning its effectiveness, cardiac surgical patients commonly receive desmopressin acetate (DDAVP) after cardiopulmonary bypass (CPB) in an effort to prevent or control bleeding diathesis. The side effects associated with DDAVP are usually considered benign. However, numerous authors have observed episodes of severe hypotension after DDAVP. As a part of a larger trial of DDAVP in routine first-time coronary artery bypass grafting (CABG), this randomized double-blind study of the hemodynamic effects of DDAVP was performed. Fifteen patients received DDAVP (0.3 microgram/kg over 15 minutes) and another 15 received saline placebo after skin closure. A statistically significant decrease in mean arterial pressure (MAP) was observed at 5 minutes after the beginning of DDAVP administration and the maximum decrease (mean change, -21 +/- 8 mm Hg, P less than 0.001) was reached as the infusion was completed. MAP did not change significantly in the control group. Hypotension after DDAVP was associated with a corresponding decrease in systemic vascular resistance. Postoperative blood loss was not different between the groups. It is concluded that routine administration of DDAVP to CABG patients is inadvisable because hemodynamic side effects are potentially dangerous and therapeutic benefit is highly unlikely.

Blood Pressure↗
PubMed1991

Renal and vascular effects of atrial natriuretic factor during cardiopulmonary bypass.

STUDY OBJECTIVE: To evaluate renal and vasodilator effects of synthetic atrial natriuretic factor (ANF) in patients undergoing cardiopulmonary bypass (CPB) with special reference to the applicability of ANF as a diuretic and natriuretic. DESIGN: The study consisted of two parts. The first 15 consecutive patients in a university hospital received a pharmacologically effective bolus dose of 100 micrograms ANF, as demonstrated previously in other studies, or placebo. After analysis of the bolus data (see "Results" section below), the 12 subsequent patients were administered ANF 50 micrograms as a constant 30-min infusion at a rate of 1.67 micrograms/min or placebo. PATIENTS: The patients were scheduled for elective coronary artery bypass grafting operation. There was no evidence of congestive heart failure in any patient, and no one had an endocrine or renal disorder. INTERVENTIONS: After achievement of hypothermia (29 to 30 degrees C of rectal temperature) during CPB, a bolus dose of ANF 100 micrograms was given or an infusion of ANF 1.67 micrograms/min for 30 min, ie, a total dose of 50 micrograms was started. The control patients received placebo correspondingly. Intravenous fluids were administered according to a predetermined scheme. MEASUREMENTS AND MAIN RESULTS: For the pharmacologic effects of ANF urine volume, urinary sodium excretion and mean arterial pressure (MAP) were measured. Only three of the eight patients receiving the bolus dose of ANF had a diuretic and natriuretic response to the drug, and the responses were significantly related (r = 0.91, p less than 0.05 and r = 0.98, p less than 0.001, respectively) to the prevailing MAP at the time of the bolus administration. The bolus dose of ANF decreased MAP significantly (p less than 0.001 vs placebo) from 65 +/- 6 (mean +/- SEM) to 55 +/- 6 mm Hg within 5 min. The infusion of ANF did not affect MAP, but it increased urine output (16.1 +/- 5.0 ml/min, when the data obtained during the 30-min infusion and a 30-min period after the infusion were combined) and urinary sodium excretion (1,651 +/- 514 microEq/min) significantly (p less than 0.05 and p less than 0.01, respectively) as compared with the corresponding values of 3.3 +/- 1.1 ml/min and 386 +/- 141 microEq/min after placebo. CONCLUSIONS: Prevailing arterial pressure is an important determinant of the diuretic and natriuretic activity of synthetic ANF in patients undergoing CPB. A low-dose infusion of ANF (50 micrograms within 30 min) provides diuresis and natriuresis without significant changes in MAP in these patients.

Atrial Natriuretic Factor↗
PubMed1990

Atrial pressure and hormonal and renal responses to acute cardiac tamponade.

The effect of acute cardiac tamponade on atrial pressures, plasma atrial natriuretic factor concentration and renin activity, and renal water and electrolyte excretion was studied in pigs loaded intravenously with hydroxyethyl starch and maintained on a continuous intravenous infusion of isotonic saline solution. Saline solution was infused into the pericardial space in 6 anesthetized pigs until a predetermined decrease of 20% in mean arterial pressure was achieved. Another 6 sham-treated pigs served as controls. Tamponade increased atrial intracavitary pressures but decreased atrial transmural (distending) pressures. These changes in atrial pressures were reversed after release of tamponade. Changes in plasma atrial natriuretic factor concentration correlated positively with changes in atrial transmural pressures. Tamponade increased plasma renin activity and decreased urine flow and renal sodium and potassium excretion, and release of tamponade reversed these changes. Thus, the tamponade-induced reduction in atrial distention is associated with hormonal changes, which may contribute to the reductions in diuresis and natriuresis observed in this connection.

Acute Disease↗
PubMed1990

Acute effects of ethanol on left ventricular diastolic function.

Transmitral flow velocities were measured by Doppler echocardiography in nine healthy men who ingested 1 g/kg of ethanol within one hour. The measurements were made before the first drink and every hour thereafter for three hours. The peak mean (SE) blood ethanol concentration was 21.4 (1.0) mmol/l. Each man was also studied after drinking fruit juice. Ethanol increased the heart rate but did not change the peak transmitral velocities, the normalised peak filling rate, the deceleration of early flow, or the duration of relaxation as measured from the second heart sound to the peak early diastolic velocity. The ratio of the peak atrial to the peak early diastolic velocity rose from 0.41 (0.03) to 0.44 (0.03) after ethanol but remained unchanged after juice. The difference between juice and ethanol was independent of changes in heart rate. The fluid balance was more negative in the ethanol experiment (-727 (114) ml v -107 (70) ml), suggesting a reduction in preload, and the ethanol-induced net loss of fluid correlated with the concomitant change in the velocity ratio. A moderate dose of ethanol causes a small acute increase of the ratio of the peak atrial to the peak early diastolic velocity of mitral flow in healthy subjects. Although this change indicates altered diastolic function of the left ventricle, most of it may result from the diuretic effect of ethanol. Any major impairment of ventricular relaxation seems unlikely.

Adult↗