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Biomedical subjects

J Jalonen

Publications and source records attributed to J Jalonen.

67 records · Page 4Linked to original sources
PubMed1981

Is there any benefit from adding single-dose cardioplegia to topical cooling of the ischaemic myocardium in aortic valve replacement operations?

The myocardial oxygen extraction, lactate metabolism and cardiac performance were studied after topical cold myocardial ischaemia (TCI) with or without associated cold potassium cardioplegia (CPL) in aortic valve replacement (AVR) patients. There were no such differences between the CPL + TCI-group and the TCI-group in the postischaemic coronary sinus blood oxygen tension, coronary sinus blood haemoglobin oxygen saturation, arterial-coronary sinus blood oxygen content difference, arterial-coronary sinus blood lactate difference, CI-PCWP or LVSWI-PCWP relationship that could be attributed to the cardioplegia. The coronary sinus blood oxygen values did not indicate any gradually developing postischaemic disturbances in the myocardial oxygen utilization. There was, however, a marked myocardial lactate washout and production in both groups five and ten minutes after initiation of reperfusion after ischaemia. There was a marked increase in the CI after bypass in the CPL + TCI-group, and the cardiodepression at late post-operative stages was minimal in both groups according to the CI-PCWP and LVSWI-PCWP relationship. These results suggest that the topical cooling technique used provides a degree of protection of the myocardial energy metabolism and function that cannot be further improved by adding single-dose cardioplegia by means of the direct coronary cannulation method used here.

Adult↗
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↗
PubMed1981

Oxygen transportation in the blood.

The most important determinants of the overall O2 delivery to tissues are the cardiac output and the arteriovenous O2 content difference. The latter is influenced mainly by the haemoglobin concentration, arterial haemoglobin O2 saturation and venous haemoglobin O2 saturation. Also the O2 tension has a minor contribution. The venous haemoglobin O2 saturation decreases, without a concomitant, potentially detrimental decrease in the venous blood O2 tension, when the haemoglobin O2 affinity decreases as a consequence of e.g. decreased pH or increased PCO2 (Bohr effect) increased temperature and increased red cell 2,3-DPG. This effect allows greater O2 extraction from the blood by tissues. The changes in the haemoglobin O2 affinity are compensated in physiological conditions by changes in the cardiac output and in the venous O2 tension. If, however, in a situation of limited tissue O2 supply these mechanisms are used up or severely compromised the haemoglobin O2 affinity becomes an important determinant of the O2 delivery to tissues.

2,3-Diphosphoglycerate↗
PubMed1980

Plasma concentrations of lidocaine (lignocaine) after cranial subcutaneous injection during neurosurgical operations.

After cranial subcutaneous injection of lidocaine 0.8-3.7 mg/kg+adrenaline (epinephrine) 1:200,000 in neurosurgical patients, fast drug absorption was found with peak plasma concentrations of 0.6-1 microgram/ml in 5-10 min. However, the concentrations remained above the lowest effective antiarrhythmic level of 0.6 microgram/ml for only about 10 min. In one patient, simultaneously administered intravenous lidocaine had an additive effect on those levels. Induced hypotension (sodium nitroprusside) during aneurysm operations decreased the arterial plasma level of lidocaine and was followed by a new peak after discontinuation. Thus the absorption of a drug during induced hypotension from subcutaneous tissue is often erratic.

Adult↗
PubMed1980

Carbon dioxide transportation and haemoglobin oxygen affinity during haemodilution.

The increase in the PCO2 of tonometered, haemodiluted (Hct 15%) blood samples was on an average 8 mm Hg higher than in the undiluted samples of the same blood when a fixed amount of Co2 was added to both samples. Concurrently the actual P50 increased on an average 2 mm Hg more in the diluted than in the undiluted samples. In a series of patients undergoing coronary artery bypass grafting the arterial-mixed venous PCO2 difference was on an average 5 mm Hg higher during haemodilution (Hct 16%) than in the control situation. In another series of similar patients the arterial-coronary sinus PCO2 difference increased from 9 +/- 1 to 14 +/- 2 mm Hg when the Hct fell to the level of 22%. The haemodilution-induced decrease in the total CO2-transporting capacity of the blood leads to an increased PCO2 and a decreased pH as compared to the situation without haemodilution, if the same amount of CO2 is added. In the clinical situation the gained decrease of the haemoglobin oxygen affinity probably plays a part in the compensation for the decreased oxygen capacity of the blood caused by the haemodilution.

Carbon Dioxide↗
PubMed1979

Continuous positive airway pressure during mechanical and spontaneous ventilation. Effects on central haemodynamics and oxygen transport.

The effect of continuous positive airway pressure during continuous mechanical (CMV + PEEP) and spontaneous (CPAP) ventilation on central haemodynamics and systemic oxygen transport was studied in 10 male patients who had undergone aortocoronary bypass graft operation 18 h earlier. With the change from CMV + PEEP 5 cmH2O to CPAP 5 cmH2O, cardiac index was found to increase from 2.58 +/- 0.44 (s.e. mean) to 2.88 +/- 0.19 l/min/m2 (P less than 0.005), and systemic oxygen transport improved from 8.5 +/- 0.6 to 9.5 +/- 1.0 ml/min/kg (P less than 0.05). Arterial oxygen tension and content did not change, but mixed venous blood oxygen tension increased from 3.5 +/- 0.2 to 4.2 +/- 0.2 kPa (P less than 0.005), reflecting the increase in cardiac output. Arteriovenous oxygen content difference decreased from 4.6 +/- 0.5 (CMV + PEEP) to 3.6 +/- 0.2 (CPAP) ml/100 ml (P less than 0.05), while total oxygen consumption remained unchanged. Mean systemic arterial pressure was found to increase from 10.8 +/- 0.4 to 11.6 +/- 0.4 kPa (P less than 0.05) and mean pulmonary arterial pressure changed from 2.2 +/- 0.1 to 2.4 +/- 0.1 kPa (P less than 0.05). Right atrial and pulmonary capillary wedge pressures did not change. Our observations suggest that, in terms of central haemodynamics and tissue oxygen supply, CPAP offers a noteworthy alternative weaning method and an alternative to CMV + PEEP in cases where therapy is prolonged and the patient is able to breathe spontaneously.

Adult↗
PubMed1979

Elevated mid-myocardial oxygen tension in the fibrillating heart during cardiopulmonary bypass.

Mid-myocardial tissue oxygen tension was measured in the left ventricular wall of the hearts of ten dogs by means of a Silastic tonometer implanted earlier. During cardiopulmonary bypass, myocardial PO2 was significantly higher in a spontaneously fibrillating heart (5.4 +/- 0.9 kPa) than during the initial beating period (3.7 +/- 0.5 kPa) or after defibrillation (4.0 +/- 0.7 kPa). In general, there was a tendency towards increased myocardial blood flow, elevated oxygen uptake and reduced coronary sinus oxygen content during ventricular fibrillation, compared with the situation in the beating heart. Myocardial lactate extraction remained unchanged during the different phases of cardiopulmonary bypass. The increase in mid-myocardial oxygen tension during ventricular fibrillation was probably due to increased total myocardial blood flow and redistribution of regional myocardial circulation. In two additional dogs, ventricular fibrillation resulted in left ventricular distension and a simultaneous fall of myocardial oxygen tension, which indicates the necessity of left ventricular decompression suction in a fibrillating heart during cardiopulmonary bypass.

Animals↗
PubMed1979

Plasma lidocaine concentrations after different methods of releasing the tourniquet during intravenous regional anaesthesia.

Different methods of tourniquet release have been proposed to decrease the concentrations of local anaesthetic released into the systemic circulation at the end of intravenous regional anaesthesia. The effect of releasing the tourniquet intermittently with 5 seconds (group I) and 30 seconds (group II) deflation periods or at once (group III) was studied in 25 adult patients after intravenous regional anaesthesia with 40 ml of 0.5% lidocaine. The venous plasma lidocaine concentrations from the contralateral arm were measured by gas chromatography. There was no leakage of lidocaine from the occluded arm into the systemic circulation. The mean maximum plasma lidocaine concentration in group I 1.99 +/- 1.45 (SD) microgram/ml, in group II 1.33 +/- 0.54 microgram/ml and in group III 1.56 +/- 0.88 microgram/ml (P greater than 0.05) was below the toxic concentrations reported in the literature. There were subjective complaints such as dizziness and ringing in the ears in 4 out of the 7 patients in group I, in 2 out of the 9 patients in group II and in one of the 9 patients in group III (P greater than 0.05). There was no correlation between the duration of tourniquet time (range 12-87 minutes) and the maximum plasma lidocaine concentration. The intermittent release of the tourniquet did not decrease the venous plasma lidocaine concentrations in the contralateral arm; neither did comparing the lidocaine pharmacokinetics in 5 patients of group II after tourniquet release and in the 5 healthy volunteers after a single 100 mg intravenous lidocaine injection reveal any differences.

Adult↗
PubMedDate not supplied

Effect of age and repeated hyperbaric oxygen treatments on vagal tone.

OBJECTIVES: To evaluate the influence of repeated hyperbaric oxygen (HBO2) exposures and age on vagal response to hyperbaric oxygenation, and to evaluate the timing of changes in vagal activity during the treatments. STUDY DESIGN: Open, controlled, non-randomized study. METHODS: Heart rate variability of 23 patients with chronic osteomyelitis or radionecrosis of the jaw or reconstructive surgery of the facial region was studied during repeated treatments. During each treatment, the patients were exposed to HBO2 at 2.5 ATA and heart rate variability was measured using power spectral analysis before compression, three times at 2.5 ATA and during and after decompression. The patients were grouped according to age (Cut-off point 50 years). Statistical analysis was carried out using analysis of variance for repeated measurements. RESULTS: Repeated exposures did not change vagal response to hyperbaric oxygenation. Vagal activity measured by HF power increased significantly in both age groups during the HBO2 exposures but there were no significant difference between the groups in the response. However, the level of HF power was significantly higher in the subjects under 50 years old. Significant differences between consecutive measurements were related to pressure changes. CONCLUSIONS: Repeated therapeutic HBO2exposures are not causing permanent changes in vagal control of the heart. Vagal responsiveness to hyperbaric hyperoxia is preserved in advanced age.

Adult↗