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Biomedical subjects

O Nyquist

Publications and source records attributed to O Nyquist.

At least 19 recordsLinked to original sources
PubMed1991

Induction of a reduction in haemoglobin concentration by enalapril in stable, moderate heart failure: a double blind study.

OBJECTIVE: To study the long term effects (12 weeks) of enalapril on central haemodynamic function and on arterial oxygen content and its determinants--haemoglobin concentration and oxygen saturation--in patients with stable moderate heart failure. DESIGN: Double blind placebo controlled randomised study. PATIENTS: 17 patients with stable moderate heart failure caused by dilated cardiomyopathy which was treated with diuretics and digoxin. METHODS: Central haemodynamic function, arterial oxygen content, arterial haemoglobin concentration, and arterial oxygen saturation were measured at rest and during submaximal exercise. Plasma volume and total body haemoglobin were determined at rest. RESULTS: With enalapril treatment heart rate, pulmonary capillary wedge pressure, mean arterial pressure, and systemic vascular resistance decreased significantly both at rest and during submaximal exercise. Cardiac output did not change at rest but tended to increase (p = 0.06) during submaximal exercise. Arterial oxygen saturation remained unchanged while haemoglobin concentration and arterial oxygen content were significantly reduced. Total body haemoglobin was significantly reduced but the plasma volume remained unchanged. At rest, the reduction in arterial oxygen content resulted in a significantly reduced mixed venous oxygen content. However, during submaximal exercise the increase in cardiac output fully compensated for the reduction in arterial oxygen content and this effect was indicated by the unaltered mixed venous oxygen content. No changes were found in the placebo group after twelve weeks. CONCLUSIONS: Enalapril unloads the heart and reduces haemoglobin concentration. During submaximal exercise, the improvement in systemic blood flow was counterbalanced by this negative effect on the oxygen carrying capacity and systemic oxygen delivery was unchanged.

Adult↗
PubMed1990

Electrophysiological effects of intravenous sotalol in acute myocardial infarction: a double-blind placebo-controlled study.

Controlled studies of the electrophysiological effects of beta-blockade in acute myocardial infarction have not previously been published. In this controlled, double-blind study 20 patients were randomized to treatment with placebo or sotalol administered as a continuous infusion for 12 h. Programmed electrical stimulation was performed from the right atrium. After 60 min of infusion in the sotalol-treated patients (n = 10) there was a significant prolongation of sinus cycle length (+15%) and sinus node recovery time (+28%). The AV nodal effective refractory period was prolonged by 15% after 45 min of infusion. Variables reflecting myocardial repolarization, atrial effective refractory period and QT interval, were increased by 20% and 10%, respectively. In the placebo group, except at 12 h, there was a general pattern of slightly diminishing values for all measured variables. The electrophysiological changes in the sotalol-treated group could be explained by the combined Class II and III activities of this drug. The infusion of sotalol was well tolerated, and the anticipated electrophysiological and Class II and III antiarrhythmic effects were observed, despite the acute myocardial infarction.

Arrhythmias, Cardiac↗
PubMed1990

Short term haemodynamic effects of converting enzyme inhibition before and after eating in patients with moderate heart failure caused by dilated cardiomyopathy: a double blind study.

The haemodynamic changes that follow a meal can mimic the response to a vasodilator drug. To avoid overestimating the beneficial effects of treatment in uncontrolled studies, measurements of haemodynamic function are usually performed with patients in the fasting postabsorptive state. But such recordings are not representative of the resting patient during daily life. In this double blind placebo controlled study the short term haemodynamic effects of enalapril were assessed during 12 hours in 19 patients with moderate heart failure caused by dilated cardiomyopathy. The patients ate lunch and dinner and were studied in the absorptive and postabsorptive phases. In the placebo group systemic vascular resistance, mean arterial pressure, and the rate-pressure product fell significantly (5-16%) after lunch. Four hours after lunch the haemodynamic function had returned to baseline--that is the postabsorptive state. Enalapril, accentuated the haemodynamic effects during the absorptive state producing a larger post-prandial fall in mean arterial blood pressure and rate-pressure product and changes in the absorptive phase were maintained into the post-absorptive phase. Pulmonary wedge pressure fell significantly after treatment with enalapril. These overall changes during the study period indicated that enalapril reduced the preload and afterload on the heart--over and above the reduction produced by eating. These findings suggest that the effects of enalapril given at rest to patients with moderate heart failure unload the heart and enhance the reduction of afterload induced by meals.

Adult↗
PubMed1990

The use of a vasodilator, felodipine, as an adjuvant to long-term oxygen treatment in COLD patients.

Eight patients with chronic obstructive lung disease (COLD) and pulmonary hypertension were given an infusion of a calcium antagonist, felodipine, during ongoing, long-term oxygen treatment (LTOT). The effects on central haemodynamics and ventilation-perfusion matching were studied. At rest pulmonary and systemic vascular resistances (PVR and SVR) were reduced by 18% (NS) and 26% (p less than 0.05), respectively. Cardiac output increased by 23%. There was a tendency to increased perfusion of low alveolar ventilation-perfusion ratio (VA/Q) areas (VA/Q less than 0.1) and to increased shunt compared to pretreatment values. Arterial oxygen tension (PaO2) fell by 0.7 kPa (p less than 0.001) but total oxygen transport increased by 23% (p less than 0.001). After treatment with oral felodipine (7.5-15 mg.day-1) for a mean time of 14 wks, PVR and SVR were reduced by 16% (p less than 0.05) and 7% (NS), respectively, as compared to pretreatment values at rest. Cardiac output rose by 13%. The VA/Q ratios and the PaO2 returned towards pretreatment values. The total oxygen transport increased by 11% (p less than 0.05) at rest and increased by 19% (p less than 0.05) during exercise as compared to the pretreatment value. The positive effect on central haemodynamics indicates that felodipine may be a valuable adjunct to ongoing LTOT.

Aged↗
PubMed1989

Energy requirement for early defibrillation.

The appropriate energy requirement for defibrillation of out-of-hospital ventricular fibrillation has been a matter of discussion. We analysed the effects of 360 J, 200 J or a combination of 200 and 360 J DC shocks given by ordinary manual defibrillators or semiautomatic defibrillators. 120 of 127 ventricular fibrillation episodes were converted by three or less 360 J DC shocks delivered by a manual defibrillator. All 28 ventricular fibrillation episodes were converted by an average of 1.9 DC shocks when 360 J were delivered by a semiautomatic defibrillator. 139 of 152 ventricular fibrillation episodes were converted by three or fewer 200 J DC shocks and 52 of 53 by 2 x 200 J followed, if needed, by 1 x 360 J DC shock delivered by the same semiautomatic defibrillator. Three or fewer 360 J DC shocks seems completely adequate for conversion of most episodes of out-of-hospital ventricular fibrillation. There is no difference in the result of defibrillation by manual and semiautomatic defibrillators.

Bioelectric Energy Sources↗
PubMed1989

One year's experience of early defibrillation in Stockholm.

The effects of resuscitation on patients who died suddenly out of hospital were evaluated after the introduction of early defibrillation performed by ambulance personnel using semi-automatic defibrillators. Resuscitation attempts were initiated in 548 patients during the 1-year study period. Mean ambulance delay was 7.5 min, 22% of the cardiac arrest patients had received bystander cardiopulmonary resuscitation (CPR). Sensitivity and specificity for the semi-automatic defibrillator in the interpretation of ventricular fibrillation was found to be 97 and 100% respectively. Only 28 (14%) of the 206 defibrillated patients regained circulation and were admitted for further hospital care. Only three survived to be discharged. Among the 342 patients in whom defibrillation was not indicated, 16 (5%) regained circulation and were admitted for further hospital care and one (0.3%) survived to be discharged. Semi-automatic defibrillators seem reliable, safe and inexpensive; however, the isolated addition of defibrillation to basal ambulance service seems to be inadequate in Stockholm. We need to evaluate what further resources are of importance to guarantee a successful outcome.

Ambulances↗
PubMed1988

Cardiac function and central haemodynamics in severe chronic obstructive lung disease. Acute and long-term effects of felodipine.

Eleven patients, with advanced chronic obstructive lung disease (COLD), received an infusion of the calcium antagonist felodipine at a rate of 0.9 mg/h. Pulmonary and systemic vascular resistances (PVR and SVR) at rest were reduced by 18% (p less than 0.05) and 33% (p less than 0.001), respectively. Cardiac output increased by 33%. The right ventricular and left ventricular ejection fractions (RVEF and LVEF), measured by equilibrium gated radionuclide ventriculography, increased by 32% (p less than 0.01) and 25% (p less than 0.01), respectively. During exercise both PVR and SVR fell by a mean of 30% (p less than 0.01). RVEF and LVEF both increased by about 14% (p less than 0.05 and p less than 0.01). After three months of oral felodipine treatment, a dose-related decrease in PVR was noted at rest (r = -0.83) compared with pretreatment values. There was an increase in RVEF which correlated to a reduction in PVR (r = -0.76). Three patients discontinued the trial due to side effects. It is concluded that the reduction of PVR induced by felodipine is accompanied by an improvement in right heart function as measured by ejection fraction measurements.

Aged↗
PubMed1987

Effects of early defibrillation of out-of-hospital cardiac arrest patients by ambulance personnel.

During the year of this study, the specially trained ambulance personnel initiated cardiopulmonary resuscitation in 307 out of hospital cardiac arrest patients. All arrests, regardless of aetiology, age or other circumstances, were studied. The mean age for the arrest patients was 66 years. The majority of arrests occurred in elderly patients at home. Although as many as 70% of the arrests were witnessed, cardiopulmonary resuscitation had been initiated in only 15% of patients before the arrival of the ambulance. One hundred and forty patients had rapid ventricular tachycardia or ventricular fibrillation when the ambulance arrived (mean delay of 7.8 +/- 3.7 min). The effects of defibrillation could be fully evaluated in 135 patients. QRS complexes, with a rate between 20 and 110 min-1, were seen after defibrillation in 94 patients, persistent asystole in 26 patients and persistent ventricular fibrillation, despite one or more 360 J DC shocks, in 15 patients. Nineteen of the 94 patients who had a return of QRS complexes also had a return of pulse shortly after defibrillation without further advanced life support measures, while another six patients had a return of pulse after further life support therapy. Six of the 32 ventricular fibrillation patients (19%) reached within 4 min and three of the 63 ventricular fibrillation patients (5%) reached between 4-8 min survived. An estimated 4.2 lives per 100,000 inhabitants a year were saved when early defibrillation was used as the only addition to the basic life support provided by the present ambulance service.

Adolescent↗
PubMed1987

Concise education of ambulance personnel in ECG interpretation and out of hospital defibrillation.

We describe an 8 hour training program for ambulance personnel in the management of cardiac arrest due to ventricular fibrillation or ventricular tachycardia. The effect of the program over a one year period is evaluated using ECG recordings and case records from the event. Emergency medical technicians manning three hospital-based ambulances were given an 8 hour theoretical and practical course followed by an examination. Fifty-nine emergency medical technicians went through the training; 52 passed the examination at the first attempt and 6 at the second (88% and 98%, respectively). The medical technicians started resuscitative procedures in 277 out of hospital cardiac arrest patients. 127 showed ventricular fibrillation at initiation of resuscitation and of these, 125 were given direct current cardioversion (DC shock) (98%). In 19 cases ventricular fibrillation persisted following defibrillation. In 9 cases no further defibrillation was attempted following our standard instructions; in the remaining 10 the ECG findings could not be interpreted by the technicians. Cardioversion was carried out in three cases, despite absence of ventricular fibrillation, one in desperation and two following misinterpretation of the ECG. A short training program for ambulance personnel seems to be sufficient with regard to the management of patients found in ventricular fibrillation and may be used by other ambulance services.

Allied Health Personnel↗
PubMed1987

Cardiac arrest in Stockholm with special reference to the ambulance organization.

During a one-year period all patients with cardiac arrest (CA) taken care of by three ambulances were studied. An incidence of 110 cardiac arrests/100,000 inhabitants/year was found. The majority of CAs affected the elderly and occurred during the day in their homes. The majority of CAs were witnessed but cardiopulmonary resuscitation (CPR) had been initiated by bystanders in only a few cases. The ambulance arrived within a mean time of 7.7 +/- 4.0 min. Forty-eight per cent of the CA patients showed ventricular tachycardia or ventricular fibrillation (VT/VF) on ambulance arrival. Patients with a prolonged ambulance delay showed a lower incidence of VT/VF than patients with a short delay. Patients in whom CPR had been initiated by bystanders showed a significantly higher incidence of VT/VF (67%) than unattended patients (45%). Bystander CPR was furthermore associated with an increased incidence of VT/VF in patients with prolonged ambulance delay. VT/VF was present at the time when the ambulance arrived in 86% of the CA patients who had received CPR from a bystander and were reached within 8 min by the ambulance.

Aged↗
PubMed1987

Prognosis and clinical follow-up of patients resuscitated from out-of hospital cardiac arrest.

A new organization has been formed in which ambulance personnel have been trained to recognize ventricular tachycardia and ventricular fibrillation (VF) and to defibrillate. Cardiac arrest (CA) occurred in 307 patients and 140 were defibrillated. Twenty-eight patients were resuscitated and admitted for further hospital care. A previous history of ischaemic heart disease was found in 24 patients. Twenty-two of the patients admitted were found to have VF, two asystole and four other rhythms. All 11 survivors regained circulation at the site of the CA. At the time of admission all but one of the patients were unconscious and one long-time survivor remained unconscious until the 5th day following admission. Seventeen patients died while still in hospital. In 16 cases a diagnosis of acute myocardial infarction was established, a further six had VF without evidence of acute myocardial infarction and six had other diagnoses. Ten out of the 11 survivors were still alive six months after discharge. Only one case of recurrent VF was seen during a median follow-up period of 16 months. Prolonged coma, especially in combination with convulsions, was associated with a poor prognosis, while early return of circulation was significantly more common among survivors. Ongoing medication with beta-blockers, a high QRS rate on admission and VF without proof of any acute myocardial infarction were also found to be more common in survivors.

Adult↗
PubMed1987

Cost of a saved life following out-of-hospital cardiac arrest resuscitated by specially trained ambulance personnel.

During a 1-year-study period three emergency ambulances manned by specially trained emergency medical technicians (EMTs) were successful in the resuscitation of 28 out-of-hospital cardiac arrest patients, who were admitted to hospital for further treatment. Nineteen patients died in hospital while nine were discharged to their homes, a survival rate corresponding to 3.5 saved lives per 100,000 inhabitants per year. The extra pre-hospital costs and the estimated costs for hospital treatment of the admitted patients amounted to 929,600 Swedish kronor (SEK). The program cost of the early defibrillation by trained EMTs accounted for only 12% of this amount, or 113,600 SEK. The cost of hospital treatment accounted for the remaining 88%, or 816,000 SEK. Intensive care accounted for 53% of the hospital costs, coronary care 4%, treatment in a general ward 33% and in a ward for rehabilitation or long-term care 10%. Non-survivors accounted for 58% of the hospital expenditure. The marginal prehospital cost (program cost) for each survivor was 12,622 SEK or approximately 1800 US dollars. The total cost per life saved was 103,000 SEK or approximately 14,700 US dollars. The estimated cost to each taxpayer of providing this extra emergency resource would be approximately 0.5 SEK a year.

Allied Health Personnel↗
PubMed1987

Experience with an automatic external defibrillator.

One emergency ambulance serving an urban part of the greater Stockholm area was equipped with a semi-automatic defibrillator Life Pack 200 Physio Control during an 8-month study period. The equipment advises the user whether defibrillation is required or not, and in cases of detected ventricular fibrillation, defibrillation is advised. The user then has to press a button to defibrillate through the same electrodes that record the electrocardiogram. A built-in tape recorder was used for documentation of the underlying rhythm disturbance. In all, advice was requested 332 times. Accuracy in interpretation of ventricular fibrillation was found to be high. The sensitivity and specificity in interpretation of ventricular fibrillation were 93% and 100%, respectively. No defibrillations were performed in patients without ventricular fibrillation. All instances of ventricular fibrillation were converted to another rhythm or asystole. Seven percent of the patients with cardiac arrest caused by ventricular fibrillation survived.

Aged↗
PubMed1986

Haemodynamic effects of intravenous sotalol in acute myocardial infarction.

There are few placebo controlled studies in acute myocardial infarction concerning the haemodynamic effects of beta blockade. In a controlled, double-blind randomized study, the haemodynamic effects of sotalol were evaluated in 20 patients with acute myocardial infarction within 24 hours of the onset. Sotalol was administered to 10 patients over 12 hours by a continuous infusion including three different infusion rates. A serum level around 1.4 microgram ml-1 was achieved after one hour of infusion. The placebo patients were given saline infusion. The patients were monitored invasively using a thermodilution catheter in the pulmonary artery. In the sotalol group, there was a significant reduction in heart rate, systolic blood pressure, cardiac output and stroke volume compared to placebo. A slight increase in the mean pressures of right atrium, pulmonary artery systolic and diastolic pressures was also seen. The infusion was well tolerated and no adverse reaction was seen.

Aged↗
PubMed1986

Long-term treatment with a new calcium antagonist, felodipine, in chronic obstructive lung disease.

Nine patients with advanced chronic obstructive lung disease (COLD) were treated with a calcium antagonist, felodipine, for 3-5 months and their central haemodynamics and pulmonary gas exchange were then studied. The systemic vascular resistance was reduced by 19% (p less than 0.05) at rest and by 30% during ergometer bicycle exercise (p = 0.05) compared to pretreatment data, whereas pulmonary vascular resistance showed a borderline reduction of 10% at rest and 30% during exercise (p = 0.12 and p = 0.10, respectively). Stroke volume increased by 13% (p less than 0.05) at rest and to the same extent at exercise. A moderate deterioration of the ventilation-perfusion relationship was seen by the multiple inert gas elimination technique, and the arterial oxygen tension was further reduced by 3.5 mmHg (p less than 0.05) at rest and by 3.0 mmHg on exercise, but the working capacity on an ergometer bicycle increased from 60 to 70 W (p less than 0.01). No acceptable predictor of patients who would respond to the drug could be found.

Calcium Channel Blockers↗
PubMed1979

Peripheral hemodynamics in assisted circulation with intra-aortic balloon pumping in patients with cardiogenic shock.

Seven patients treated for cardiogenic shock were studied with and without intra-aortic balloon pumping (IABP). Calf and forearm blood flows were determined with a Dohn plethysmograph and arterial pressures were registered intra-arterially and in the great toe and thumb with the cuff method. During IABP, an augmented flow was registered in the arms and legs and accurate arterial BPs could also be determined from the extremities. The findings demonstrate a beneficial effect of IABP on peripheral flow, expecially in patients who could be weaned off the pump.

Aged↗
PubMed1979

Mortality, arrhythmias and pump failure in acute myocardial infarction in relation to estimated infarct size.

Serial estimations of total serum creatine kinase (S-CK) were made in 194 consecutive patients with acute myocardial infarction (AMI). By itself, the maximum CK value could not separate patients in terms of high and low mortality but when the maximum CK value was related to age for patients with and without a history of previous AMI, two subgroups became apparent, one with 46% mortality (high-risk group) and another with 6% (low-risk group) during the hospital stay plus the next 90 days. In 114 of the patients, infarct size could be calculated. A good correlation was found between maximum CK and calculated infarct size (r = 0.93). Calculated infarct size alone could not distinguish between high and low mortality but when it was related to age for patients with and without a history of previous AMI, two subgroups emerged, one with 43% mortality and another with 3% during the hospital stay plus the next 90 days. The incidence of ventricular tachycardia during the stay in the Coronary Care Unit did not differ between the two risk groups separated either by maximum CK value or calculated infarct size. However, the incidence of shock and severe left heart failure during the acute phase was higher in the high-risk groups.

Acute Disease↗