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Biomedical subjects

V Laaksonen

Publications and source records attributed to V Laaksonen.

At least 19 recordsLinked to original sources
PubMed1996

Static-charge-sensitive bed ballistocardiography in cardiovascular monitoring.

We evaluated the autonomic influence on balistocardiograms recorded by a static-charge-sensitive bed for cardiovascular monitoring in nine healthy males (20-44 years) and its clinical use in 11 patients who underwent coronary bypass surgery (51-59 years). The ballistocardiogram displayed a distorted low amplitude from the empty beating heart during bypass surgery, impaired by a reduced effective transmural filling pressure of the heart, and returned to its pre-bypass level when the preload to the heart and its pumping was restored. Submaximal dynamic exercise and isoprenaline caused the heart rate to rise to 90-114 beats min-1, and increased the ballistocardiographic amplitude threefold, while at the same time shortening the interval between the R-wave of the electrocardiogram and the peak of the ballistocardiographic waveform (P < 0.01). In contrast, atropine accelerated the heart rate to 96 beats min-1, but did not significantly change the amplitude or temporal pattern of the ballistocardiogram. Thus, the ballistocardiogram reflects sympathetic and parasympathetic influence on the contractility of the myocardium and the effect of cardiac filling (e.g. during bypass surgery).

Adult↗
PubMed1989

Myocardial oxygen balance and cardiopulmonary bypass in patients undergoing coronary artery bypass grafting.

The frequency of anaerobic myocardial metabolism was studied in 14 patients undergoing coronary artery bypass surgery during enflurane-supplemented high-dose fentanyl anesthesia and compared with other clinical monitors of myocardial ischemia including the configuration of the pulmonary capillary wedge pressure (PCWP) and electrocardiographic findings. Hemodynamic parameters, coronary sinus blood flow, myocardial oxygen and lactate extractions, and a seven-lead ECG were recorded before and after cannulation of the aorta and vena cava, during total cardiopulmonary bypass (CPB) in a vented heart, during rewarming after global myocardial ischemia and cold cardioplegia, and 15 minutes after coming off bypass. The cannulation for CPB induced no changes in the central or coronary hemodynamics, but four patients had abnormal lactate metabolism. Two of these also had ST segment depression, and two had prominent AC waves on the PCWP tracing. Coronary sinus blood flow and myocardial oxygen extraction were maintained at the beginning of CPB, but lactate extraction decreased markedly or turned to lactate production, and ECG changes indicating myocardial ischemia were seen in five patients. During rewarming and after CPB, all patients had abnormal lactate metabolism despite decreased myocardial oxygen extraction, adequate coronary perfusion pressure, and adequate coronary sinus blood flow. During these periods most patients also had cardiac conduction disturbances that made the interpretation of the ST segment impossible. Only one patient had clearly abnormal AC and V waves on the PCWP tracing after CPB. Two patients had ECG evidence of a perioperative myocardial infarction, but they had no significant clinical consequences. Four patients had a fascicular block at discharge. These results indicate that anaerobic myocardial metabolism is common during and after CPB, and that associated myocardial ischemia cannot always be reliably detected by changes in the ECG or the PCWP tracings.

Anaerobiosis↗
PubMed1987

Low-dose enflurane as adjunct to high-dose fentanyl in patients undergoing coronary artery surgery: stable hemodynamics and maintained myocardial oxygen balance.

The effects of enflurane (end-tidal concentration 0.7%) on central and coronary hemodynamics and myocardial oxygenation were studied during steady state, high-dose fentanyl anesthesia in ten patients undergoing coronary artery bypass grafting operations. Compared with the response in ten patients receiving the same fentanyl anesthesia (100 micrograms/kg) without enflurane supplementation, enflurane caused a moderate reduction in mean arterial pressure, systemic vascular resistance, and left ventricular stroke work index. No patient showed signs of myocardial ischemia, and mean coronary sinus flow and calculated coronary resistance remained unchanged. Surgical stimulation induced no central or coronary hemodynamic responses in the enflurane-fentanyl group. No coronary hemodynamic changes occurred in the fentanyl group, but a marked increase in arterial pressure and systemic vascular resistance was seen. Myocardial oxygen extraction decreased in the enflurane supplemented group although it increased in the fentanyl group after surgical stimulation. Three fentanyl group patients and one enflurane-fentanyl group patient had a low myocardial lactate extraction as a sign of myocardial ischemia during surgery. We conclude that a 0.7% enflurane supplementation of 100 micrograms/kg fentanyl anesthesia does not endanger myocardial oxygenation and effectively prevents central and coronary hemodynamic responses to skin incision and sternotomy in patients undergoing coronary artery surgery.

Anesthesia, General↗
PubMed1985

Surgical stimulation during high-dose fentanyl anaesthesia: effects of dehydrobenzperidol on the haemodynamics and myocardial oxygenation.

Twenty-four patients undergoing a coronary artery bypass grafting operation with high-dose fentanyl (100 micrograms/kg)-lorazepam-oxygen anaesthesia were divided into a control group and a group receiving in addition 0.25 mg/kg dehydrobenzperidol (DHBP) before the skin incision (DHBP-group). The changes in the central and coronary haemodynamics and the myocardial oxygenation were studied and compared between the two groups during the skin incision and sternotomy, in order to evaluate the possible effects of the dehydrobenzperidol in preventing the harmful haemodynamic effects of surgical stimulation during high-dose fentanyl anaesthesia. In the control group a marked increase in the systemic vascular resistance and mean arterial pressure was seen during surgery. This haemodynamic stimulation was prevented by dehydrobenzperidol during the skin incision and markedly reduced during the sternotomy. Regardless of whether or not DHBP was given, a significant increase in the myocardial oxygen consumption was observed during the sternotomy; in the control group, the increase was slightly higher and was compensated by a greater increase in the myocardial oxygen extraction. No significant changes were seen in the coronary sinus blood flow or coronary vascular resistance in either group during the study period. The surgery caused no change in the myocardial lactate extraction in either group, although myocardial lactate production was observed in one control patient and the myocardial lactate extraction was markedly reduced in two other control patients and one DHBP patient.

Coronary Artery Bypass↗
PubMed1985

Haemodynamics and myocardial oxygenation during anaesthesia for coronary artery surgery: comparison between enflurane and high-dose fentanyl anaesthesia.

Changes in central and coronary haemodynamics and myocardial oxygenation during anaesthesia induction, intubation, skin incision and sternotomy were studied in 24 patients undergoing a coronary artery bypass grafting operation under either high-dose fentanyl or enflurane anaesthesia. The anaesthesia induction caused no changes in the coronary haemodynamics in either group, in spite of a marked decrease in the coronary perfusion pressure during enflurane induction. In both groups a decrease in the coronary sinus blood flow and an increase in the coronary vascular resistance was observed after the intubation. At this stage, two patients in both groups had a low level of myocardial lactate extraction, indicating possible myocardial ischaemia; mean myocardial lactate extraction had decreased significantly from the awake level in both groups. A circulatory response to surgical stimulation was seen in both groups, although it could be somewhat better controlled during enflurane anaesthesia. In the enflurane patients the increase in myocardial oxygen demand was accompanied by increased coronary flow, while in the fentanyl group the increase in coronary flow was not in proportion to the increased oxygen demand, and an increase in myocardial oxygen extraction was also seen. During surgery, three fentanyl patients and one enflurane patient had a low level of myocardial lactate extraction.

Anesthesia, General↗
PubMed1985

Midazolam kinetics before, during and after cardiopulmonary bypass surgery.

Gas-chromatographically determined serum concentrations of midazolam were recorded before, during and after cardiopulmonary bypass in patients scheduled for a coronary artery bypass grafting operation. Following single 0.075 mg/kg (n = 6) and 0.15 mg/kg (n = 6) intravenous injections of midazolam, a mean distribution phase half-life of 3.4 and 4.4 min respectively was calculated. At the establishment of the bypass, a rapid drop in the concentration of midazolam was observed followed by a significant increase in concentration during the postperfusion period. The apparent mean elimination phase half-life (281 min) of midazolam was longer than that (about 120 min) measured in earlier works in young, healthy subjects. Thus the metabolism of midazolam during the postperfusion period appears to be slower.

Benzodiazepines↗
PubMed1984

Lorazepam and high-dose fentanyl anaesthesia: effects on haemodynamics and oxygen transportation in patients undergoing coronary revascularization.

The effects of intravenous lorazepam (0.05 mg/kg) on haemodynamics and oxygen transportation were studied in a group of 11 patients undergoing a coronary artery bypass grafting operation with high-dose fentanyl anaesthesia and compared to the changes in another group of 11 patients receiving the same anaesthesia, but saline instead of lorazepam. The measurements were made under stable haemodynamic conditions before the injection of lorazepam or saline, and repeated 5, 20 and 40 min after the injection. Lorazepam caused a slight decrease in the systemic and pulmonary arterial pressures and in the left ventricular stroke work index, as compared to the control group. The ECG or the rate-pressure product did not show changes indicative of myocardial oxygen supply/demand imbalance in either group. There was a similar decrease in the systemic oxygen transportation and an increase in the arterio-venous oxygen content difference in both groups, but the unchanged systemic oxygen consumption and arterial lactate level suggest a well-maintained tissue oxygenation. It is concluded that intravenous lorazepam does not cause important haemodynamic untoward effects as an adjunct to high-dose fentanyl anaesthesia in patients undergoing coronary artery bypass grafting.

Adult↗
PubMed1984

Metoprolol medication and coronary artery bypass grafting operation.

Twenty patients undergoing a coronary artery bypass grafting operation with high-dose fentanyl anaesthesia, all on long-term metoprolol medication, were randomly divided into a metoprolol group (last metoprolol dose given 1.5 h before the anaesthesia) and a control group (last metoprolol dose 12 h before the anaesthesia). Haemodynamics were measured and the ECG was recorded serially in order to compare the responses to the anaesthesia induction and skin incision in these two groups and to evaluate possible harmful effects of the maintained metoprolol medication. The ECG showed ischaemic signs in five control group patients during the anaesthesia induction; these patients also had a relatively high rate-pressure product. No metoprolol group patient developed ECG changes indicative of ischaemia at this stage, despite a low plasma metoprolol concentration in two patients. Surgical stimulation caused no signs of myocardial ischaemia in either group. There were no inter-group differences in the haemodynamics or oxygen transportation. No harmful effects of the maintained metoprolol on the post-bypass cardiac performance nor on the occurrence of rhythm or conduction disturbances could be seen, although a high plasma metoprolol concentration was maintained in several metoprolol group patients over the bypass time. It is concluded that continuation of long-term metoprolol medication up to 1.5 h before high-dose fentanyl anaesthesia for coronary artery bypass grafting has no harmful effects on the haemodynamics during the operation or the restoration of the cardiac function after the cardiopulmonary bypass, but it evidently does help to maintain the myocardial oxygen supply/demand balance during the anaesthesia induction.

Anesthesia, Intravenous↗
PubMed1984

Midazolam as adjunct to high-dose fentanyl anaesthesia for coronary artery bypass grafting operation.

The usefulness of midazolam as an adjunct during high-dose fentanyl anaesthesia was studied by following the changes in the haemodynamics and total body oxygenation after an intravenous injection of 0.075 mg/kg and 0.15 mg/kg of midazolam during the induction of fentanyl (75 micrograms/kg)-oxygen anaesthesia for a coronary artery bypass operation. These responses were then compared to the changes seen in patients receiving the same fentanyl anaesthesia without the midazolam. A rapid decline after the midazolam injection was seen in the mean systemic arterial pressure (24-32%--the lowest individual value was 45 mmHg (6.0 kPa)) and in the systolic and diastolic pulmonary arterial pressures (29-33% and 30-31%) in 1-3 min. As measured 10 min after the midazolam injection, a decrease from the baseline was seen in the stroke index (25-30%), in the left ventricular stroke work index (46-42%) and in the right ventricular stroke work index (48-61%). These haemodynamic variables remained on a lower level throughout the study period (40 min) in the midazolam patients as compared to the controls. The tissue oxygenation seemed to be sufficient in all groups during the study period. An intravenous injection of a relatively low dose of midazolam during the induction of high-dose fentanyl anaesthesia seems to be followed by rapidly increased venous pooling and a moderately to severely decreased systemic arterial pressure. Based on the results of this study, midazolam cannot be recommended as an adjunct during high-dose fentanyl anaesthesia.

Adult↗
PubMed1984

Myocardial oxygen balance during hemodilution in patients undergoing coronary artery bypass grafting.

The myocardial (arterial-coronary sinus) balance of oxygen and lactate was studied before a cardiopulmonary bypass and during the first 5 min of a normothermic bypass in two patient groups undergoing coronary revascularization for multiple coronary artery disease. The hemodilution (HD) group was hemodiluted before the bypass with dextran 70 (15 ml/kg; resulting mean hematocrit 32%) and further at the beginning of the bypass due to nonhemic priming of the oxygenator (mean hematocrit 15%). The control (C) group was not diluted before the bypass, and four units of red blood cells were included in the oxygenator priming (mean hematocrit 27% after the beginning of the bypass). The preoperative dilution produced a decline in the coronary sinus blood oxygen tension and oxygen saturation, but no change in the arterial-coronary sinus lactate balance. After the first 5 min of the bypass, the heart produced lactate in both the HD group and the C group, but the lactate production was more pronounced in the HD group. At the same time, the coronary sinus blood oxygen saturation was lower in the HD group than in the C group. Hypotension frequently accompanied the beginning of the bypass in both groups. It is concluded that the hemodilution to a hematocrit level of 32% in patients undergoing coronary revascularization for multiple stable coronary artery disease produces compensatory changes in myocardial oxygen extraction, but no changes of a generalized ischemia can be demonstrated. The hemodilution to a hematocrit level of 15% produces myocardial ischemia in patients with a normothermic unloaded heart, adding to the effect of hypotension at the beginning of the bypass.

Adult↗
PubMed1984

Use of activated clotting time to monitor anticoagulation during cardiac surgery.

The use of a fixed dosage schedule was compared with the use of activated clotting time (ACT) for monitoring heparin anticoagulation and its neutralization during and after extracorporeal circulation in patients undergoing coronary artery bypass grafting. Use of ACT resulted in a statistically significant decrease in heparin and protamine dosages and statistically significant reductions in postoperative blood loss and blood transfusion needs. Postoperative levels of blood hemoglobin concentration were significantly higher and the activated partial thromboplastin time was significantly shorter with ACT monitoring than with use of a fixed dosage schedule. The results confirmed the superiority of the ACT method for monitoring anticoagulation during cardiac surgery.

Blood Coagulation Tests↗
PubMed1983

Effects of extreme haemodilution on the immediate post-operative course of coronary artery bypass patients.

The immediate post-operative course was investigated in 70 patients who had undergone coronary artery bypass grafting under normovolaemic moderate and subsequent extreme haemodilution, and in 70 control patients who underwent a similar operation with a haemic prime in the heart-lung machine. Altogether 8 patients (5.7%), 4 from the haemodilution group and 4 from the controls required re-exploration for excessive post-operative bleeding and were examined as their own group. There were no marked differences in bleeding through chest tubes or in blood haemoglobin concentration between patients who had undergone intra-operative haemodilution and controls. Post-operatively both patient groups required approximately analogous amounts of infused blood, colloids and crystalloids. Central venous pressure was consistently lower in haemodiluted patients. Opening of peripheral circulation as indicated by a rise in skin temperature occurred significantly faster in haemodiluted patients than in controls. Before and after weaning from the respirator, arterial blood oxygen tension was slightly lower in patients who had undergone intra-operative haemodilution. Serum creatinine levels were lower and blood platelet counts significantly higher in haemodiluted patients than in controls. Rates of peri-operative myocardial infarctions showed no essential difference between the groups.

Adult↗
PubMed1982

Annulo-aortic ectasia involving the aortic arch. Total replacement using a composite graft. A case report.

A case of annulo-aortic ectasia involving the aortic arch and the proximal part of the left subclavian artery is reported. The aorta was replaced with a composite graft (Björk-shiley tilting disc valve and very soft Cooley low-porosity prosthesis) and the coronary ostia and the innominate and left common carotid arteries were implanted directly into the prosthetic tube. The patient recovered without complications.

Adult↗
PubMed1981

Oxygen transport to tissue under normovolemic moderate and extreme hemodilution during coronary bypass operation.

Oxygen transport to tissue was studied in 12 patients undergoing coronary bypass operation under normovolemic moderate and extreme hemodilution. Normovolemic moderate hemodilution (15 ml per kilogram of body weight), carried out immediately after induction of anesthesia, decreased the mean hematocrit from 0.43 to 0.33. Simultaneously, the cardiac index and the left ventricular filling pressure increased slightly but the systemic oxygen transport was reduced by 20%. The subcutaneous tissue oxygen tension (PO2) was approximately 40 mm Hg after induction of anesthesia and underwent a transient increase during moderate hemodilution. During cardiopulmonary bypass and extreme hemodilution, the mean hematocrit declined to 0.16. Concurrently, the mean tissue PO2 fell sharply and reached a minimum of 14 mm Hg at deepest hypothermia. After decannulation and reinfusion of autologous blood, the PO2 rose to 30 mm Hg. In general, total-body oxygen consumption changed along with tissue PO2. Blood lactate concentration underwent a clear increase in the early phase of extracorporeal circulation and remained rather stationary thereafter. No perioperative myocardial infarctions were encountered, and each patient made an uneventful recovery.

2,3-Diphosphoglycerate↗
PubMed1981

Oxygen transport and tissue oxygenation under moderate and extreme hemodilution during coronary bypass surgery.

Oxygen transport and tissue oxygenation were investigated in twelve patients undergoing coronary bypass surgery under normovolemic moderate and extreme hemodilution. Moderate hemodilution, that was carried out after induction of anesthesia, decreased the mean hematocrit from 0.43 to 0.33. Concurrently, the cardiac index and the left ventricular filling pressure increased slightly whereas the systemic oxygen transport declined by 20%. This was associated with elevated oxygen extraction. The subcutaneous tissue oxygen tension underwent a transient increase during moderate hemodilution. During cardiopulmonary bypass and extreme hemodilution the mean hematocrit declined to 0.16. Simultaneously, the tissue PO2 decreased clearly reaching its minimum at the deepest hypothermia. After coming off bypass and reinfusion of the autologous blood the tissue PO2 approached the preoperative levels. In general, total body oxygen consumption changed parallelly with the tissue oxygen tension. Lactate concentration in the mixed venous blood increased in the beginning of the extracorporeal circulation and remained rather stationary thereafter. All patients recovered normally without any perioperative myocardial infarctions.

Adult↗
PubMed1981

Serum oncocity and myocardial oxygen balance during haemodilution in open-heart surgery.

In the first part of the present study the colloid-oncotic properties of degraded gelatin and dextran 70 were compared with each other during moderate normovolemic and extreme haemodilution. Serial serum analyses of colloid oncotic pressure and albumin concentration were performed on 39 open-heart surgery patients. The profile of albumin changes during the 24-hour period beginning with preanaesthetic measurements was identical in both colloid-groups. The data obtained strongly support the supposition that the gelatin solution easily escapes from the circulation due to gelatin's low number average molecular weight. On the other hand the oncotic and haemodynamic effects of dextran 70 may continue for many hours; dextran 70 seems therefore to be an ideal colloid for haemodilution. The second part of the study comprised an investigation of the effects on myocardial oxygen and lactate balance of moderate and extreme haemodilution with dextran 70 on 11 patients undergoing coronary bypass surgery. To compensate fully for the observed decrease in the blood O2-capacity during normovolemic haemodilution (Hct fell from 44 to 32), the coronary blood flow should have been increased by 24% in addition to the increase observed in the myocardial oxygen extraction. The compensation was considered adequate, because no myocardial ischaemia, as judged by the unchanged myocardial lactate balance, developed. The coronary sinus blood samples are, however, a poor reflection of local myocardial metabolic changes in those areas, where coronary flow is most severely restricted.

Blood Physiological Phenomena↗