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Biomedical subjects

F Knudsen

Publications and source records attributed to F Knudsen.

At least 37 records · Page 2Linked to original sources
PubMed1993

Accuracy of 94 anaesthetic agent vaporizers in clinical use.

Using the Brüel & Kjaer Anaesthetic Gas Monitor type 1304, we have monitored the output of 94 anaesthetic agent vaporizers (Fluotec 3:58, Enfluratec 3:24, Isotec 3:12), in seven departments of anaesthesia, at different dial settings and flow rates. The range of output, for one type of vaporizer and dial setting (flow: 6 litre min-1) was largest with the Fluotec 3 (0.85-1.55% when dial set to 1%) and smallest with the Isotec 3 (0.85-1.15% when dial set to 1%). In determining the number of vaporizers with unacceptable inaccuracy, we applied acceptance limits of +/- 15% relative on each vaporizer and each dial setting. Using a flow of oxygen 6 litre min-1 17% of Fluotec 3.8% of Isotec 3 and 71% of Enfluratec 3 vaporizers had outputs outside those limits. Even when some specific conditions (vaporizers giving output beyond the limits at any two or more dial settings; output beyond the limits in the clinically relevant range (0.5-2%)) were added, a substantial number of vaporizers did not perform within the limits. We found a significantly greater accuracy of the vaporizers after 3-monthly calibration checks (P < 0.05) compared with vaporizers undergoing service and calibration only annually. Using a questionnaire, we found that fewer than 30% of the anaesthetists using the vaporizers would accept aberrance beyond +/- 10% relative of the dial setting.

Anesthesia, Inhalation↗
PubMed1993

High prevalence of hepatitis C virus (HCV) RNA in dialysis patients: failure of commercially available antibody tests to identify a significant number of patients with HCV infection. Copenhagen Dialysis HCV Study Group.

Results of serologic tests were correlated with hepatitis C virus (HCV) viremia, determined by a cDNA polymerase chain reaction assay to detect HCV RNA, in 340 Danish dialysis patients; of these, 28 (8.2%) were positive for antibodies to HCV (anti-HCV) with second-generation ELI-SAs. HCV RNA was found in sera from 27 of these 28 anti-HCV-positive patients. However, 8 dialysis patients had detectable levels of HCV RNA but were anti-HCV-negative with second-generation ELISAs. Among the 35 HCV-infected dialysis patients 16 were positive, 7 indeterminate, and 12 negative with the second-generation RIBA. More than 60% of patients with evidence of ongoing liver disease had HCV infection. Thus, current commercially available antibody tests did not accurately reflect the HCV status in dialysis patients. A relatively high prevalence (> 10%) of HCV RNA, closely associated with liver disease, was found among dialysis patients in a low-prevalence area of the world.

Base Sequence↗
PubMed1993

The influence of nitrous oxide on recovery of bowel function after abdominal hysterectomy.

The influence of nitrous oxide on the recovery of bowel function was studied in 36 patients anaesthetised for elective abdominal hysterectomy with or without salpingo-oophorectomy. Patients were randomly assigned to receive either isoflurane in nitrous oxide and 30% oxygen (N2O group) or isoflurane in air and 30% oxygen (Air group). Anaesthetic management included thiopentone, fentanyl, suxamethonium and atracurium. The lungs were not ventilated prior to intubation. Before closing the abdomen, the surgeon assessed the degree of distension of the intestines and the closing conditions. Postoperative nausea and vomiting was assessed 2, 6, 12 and 24 h after recovery from anaesthesia. The lapse of time before mobilisation and passing of flatus and faeces was recorded. The patients in the Air group were significantly older than the patients in the N2O group (48.9 years versus 44.0 years, P = 0.04); otherwise, there were no differences in the demographic data of the patients. We found no significant differences between the groups with respect to nausea and vomiting, distension of the intestines before closure of the abdomen, closing conditions, time elapsing before mobilisation, constipation before recovery of bowel function or time elapsing before passing of flatus. We found a statistically significant delay of 10.3 h in time elapsing before passing of faeces in the N2O group compared to the Air group (P = 0.04), suggesting a potentially adverse effect of nitrous oxide.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Haemostatic activation in patients with head injury with and without simultaneous multiple trauma.

In a prospective study including 16 patients with multiple trauma and head injury and 14 patients with isolated head injury we measured plasma levels of prothrombin fragment 1 and 2 (F1 + 2) and thrombin/antithrombin III complex (TAT) on admission and on days 1, 2, 3, and 7 after the incident. On admission, all patients had values of F1 + 2 and TAT above the reference range. Admission levels of both F1 + 2 and TAT were significantly higher compared with levels on the following days. Admission levels of F1 + 2 was significantly correlated to the Injury Severity Score. TAT was higher in patients with multiple trauma than in patients with isolated head injury and were significantly correlated to the Injury Severity Score on admission and on day 3. Levels of F1 + 2 were significantly lower on day 1 in four patients with post-traumatic pulmonary dysfunction compared with patients without pulmonary dysfunction. With respect to levels of TAT, no differences were detected between patients with and without pulmonary dysfunction.

Adolescent↗
PubMed1992

Anesthesia and complications of extracorporeal shock wave lithotripsy of urinary calculi.

The techniques of anesthesia for extracorporeal shock wave lithotripsy of urinary calculi and the associated complications in 600 treatments with the second generation lithotriptor Siemens Lithostar were studied. General anesthesia was used in 17 treatments (2.8%) and epidural anesthesia was applied in 73 (12%), primarily in children and patients in need of simultaneous surgical auxiliary procedures. A total of 510 treatments (85%) was performed with a combination of local infiltration anesthesia and supplementary intravenous opiates. In 65% of the cases only 2 injections of opiates were sufficient for pain relief. There were no complications in 394 treatments (77%) and minor complications, such as arrhythmia (9.2%) and nausea/vomiting (7.6%), were easily treated. Respiratory depression was observed in 10 cases (2%) and this potentially dangerous complication was associated with simultaneous administration of opiates and midazolam. Only 9 treatments (1.8%) had to be terminated due to complications. It is concluded that most treatments of urinary calculi with this second generation extracorporeal shock wave lithotriptor can be performed with local infiltration anesthesia combined with supplementary short-acting opiates intravenously for pain relief and sedation. When administering supplementary midazolam for sedation the risk of respiratory depression should be considered.

Adolescent↗
PubMed1992

The value of exercise tests after acute myocardial infarction.

The aim of the present study was to relate the clinical course in patients after a first acute myocardial infarction with the response to exercise-tests performed one month after discharge. 90 consecutive patients who suffered an acute myocardial infarction for the first time were followed-up after 12 months in general practice. Six patients had died, and nine patients had suffered another MI. 23 patients were being treated for heart failure, 51 for angina pectoris, and 8 for arrhythmias. 14 patients received treatment for both heart failure and angina pectoris. Of the patients at work, 17.6% did not return to work because of the heart disease. 80 patients were in function groups I-II and 10 in function groups III-IV (New York Heart Association's Classification). Occurrence of ST-segment displacements was without prognostic value. Left ventricular function index (dRPP) and working capacity (W) were predictive with respect to mortality, heart failure, and angina pectoris requiring drug treatment. Exercise tests following acute myocardial infarction could not predict the chances of returning to work.

Adult↗
PubMed1992

The influence of tourniquet ischaemia on post-operative degranulation of polymorphonuclear granulocytes.

Degranulation of polymorphonuclear granulocytes following minor surgery and the contributory role of temporary tissue ischaemia in a limb were examined in 22 otherwise healthy patients undergoing elective arthroscopy under general anaesthesia with and without tourniquet. Apart from an increase in lactate levels following tourniquet release there was no difference in complement split product C3d, cortisol, leukocyte or creatinine kinase levels between the two groups. There was a post-operative increase in the plasma E alpha 1-proteinase inhibitor concentration, whereas lactoferrin values decreased 4 h following tourniquet deflation. Anaesthesia and minor surgery are followed by post-operative release of polymorphonuclear neutrophil elastase. This release is not related to complement activation and is apparently unaffected by 50 min of lower limb ischaemia. Anaesthesia and minor surgery do not cause lactoferrin release.

Adolescent↗
PubMed1991

[Neurogenic pulmonary edema].

Neurogenic pulmonary oedema (NPE) is a recognized, serious, relatively uncommon, acute complication of cerebral insults of various types. Despite numerous animal experimental investigations and case reports, the pathological physiology is not yet elucidated. An acute cerebral insult with raised intracranial pressure is accompanied by violent activation of the sympathetic system and increase in the concentrations of circulating catecholamines. Probably, hydrostatic influences and altered capillary permeability both play roles in the pathogenesis. Acute increase in the total vascular surface in the lungs may also be contributory. Treatment includes intubation and positive pressure ventilation, diuretics, infusion of synthetic catecholamines, alpha-receptor blockades and reduction of raised intracranial pressure by hyperventilation and drainage of liquor. The optimal treatment of NPE is not yet established on account of insufficient knowledge of the pathological physiology.

Brain Injuries↗
PubMed1991

[Prevention of the TURP syndrome by using the Swan-Ganz catheter in a patient with severe aortic stenosis].

A patient with a severe valvular aortic stenosis, who required transurethral resection of the prostate, was monitored with a Swan-Ganz catheter. Overloading of the patient due to absorption of irrigating fluid was quickly reflected by elevation of pulmonary artery pressure PAP and pulmonary capillary wedge pressure PCWP, while the central venous pressure CVP was unchanged. Monitoring of PAP and PCWP may prevent the development of the TURP-syndrome in patients with compromised left sided cardiac function.

Aged↗
PubMed1991

[Coagulation disorders in traumatic brain injuries].

Exposure of subendothelial collagen and release of tissue thromboplastin render possible activation of both the internal and external coagulation cascades in traumatic lesions of the brain. Disseminated intravascular coagulation (DIC) is well described in brain lesions and may contribute to the haemorrhagic tendency in brain-injured patients. DIC is also suggested as a contributory factor for the degree of secondary brain damage and the development of pulmonary complications and tardive intracranial haematomata. The literature concerning DIC and traumatic brain damage is, however, difficult to assess as many of the materials include multitraumatized patients and the diagnostic criteria for DIC vary. In addition, it is difficult to differentiate between normal physiological phenomena and genuine pathological processes. No controlled and randomized investigations concerning the effects of specific antithrombotic treatment of DIC in traumatic lesions of the brain are available. It is recommended that patients with brain injuries should be examined for the development of disturbances of coagulation and that the relevant laboratory investigations should be included in assessment of this patient group.

Brain Damage, Chronic↗
PubMed1991

[Blood transfusion and Jehovah's witnesses. Ethical and medicolegal aspects].

Jehovah's witnesses refuse transfusion of blood and blood products on the basis of religious convictions even when transfusion is considered necessary to save life. Medical treatment of these patients presents an ethical challenge for the physicians. The legal aspects of either administering blood to or withholding necessary blood transfusion from a Jehovah's witness are not clarified. Competent adult patients cannot be treated against their will. Children and unconscious patients must be treated according to "jus necessitatis". Whether a competent advance directive from a patient before an operation in general anaesthesia can be or must be respected is legally obscure. Final clarification of the patients' rights and the physicians' legal status could be obtained by an amendment to the existing Practice of Medicine Acts as proposed in the report (1184) from the Danish Ministry of Justice. The ethical aspects of administering blood to or withholding blood from these patients are also complex. It is recommended to determine one's own attitude individually and to inform the patient about this before an operation.

Blood Transfusion↗
PubMed1991

Does the method of heparinisation influence the biocompatibility of dialysis membranes?

The biocompatibility of cuprophanc haemodialyser membranes was investigated during two haemodialysis sessions in ten stable male chronic haemodialysis patients. In one session heparin was given intravenously, while it was given in the arterial line in the other session, using the same amount of heparin and the same filter. Biocompatibility was determined by measuring platelet and leukocyte counts, plasma beta-thromboglobulin, C3d, elastase, and lactoferrin in the arterial line at 0, 10, and 90 min of dialysis, and in the venous line at 10 and 90 min. Adequate anticoagulation was ensured by determining activated partial thromboplastin time. Platelet counts remained unchanged, whereas leukocyte counts transitorily decreased during dialysis. Plasma beta-thromboglobulin, C3d, elastase, and lactoferrin increased during haemodialysis, but no differences could be found between the two methods of heparinisation. The activation of complement, platelets, and leukocytes seemed to be independent of the mode of heparinisation.

Adult↗
PubMed1991

Silent ischemia and severity of pain in acute myocardial infarction.

An overall low tendency to complain of pain, due to a low perception of pain, has been suggested in the pathogenesis of silent ischemia, independent of the extent of the diseased coronaries and a history of previous acute myocardial infarction. This hypothesis has been tested indirectly in this retrospective study by comparison of the use of analgesics during admission for a first acute myocardial infarction with the occurrence of silent ischemia at exertion tests four weeks after discharge from hospital. The study did not show a lower use of analgesics in patients with silent ischemia, but this may be due to methodologic problems. Suggestions are given for another study design to overcome these problems.

Analgesics, Opioid↗
PubMed1991

Attenuation of intra-operative surgical stress response has no influence on post-operative degranulation of polymorphonuclear granulocytes.

Degranulation of polymorphonuclear (PMN) granulocytes, complement activation, and the endocrine metabolic response to hysterectomy were compared in two groups of patients receiving either general anaesthesia (GA group) or combined epidural analgesia and general anaesthesia (GAE group). The B-leucocyte and the cortisol responses were attenuated in the GAE group. There was no sign of complement activation. The post-operative rise in elastase-alpha-1-proteinase levels 4 h post-operatively on the first, second and third post-operative days was similar in the two groups. Plasma lactoferrin values were significantly elevated 4 h post-operatively and reached pre-operative values on Day 1 in both groups. Attenuation of the surgical stress response during uncomplicated hysterectomy did not influence the post-operative increase in proteinase activity. Mediators generated at the site of surgical trauma may account for the PMN degranulation observed after major surgery.

Adult↗
PubMed1991

Fibre-optic bronchoscopic evaluation of tracheal tube position.

Verification of tracheal tube position by fibre-optic bronchoscopy was evaluated in 20 critically ill adult patients. The distance between the carina and the tube was measured by direct visualization with a fibre-optic bronchoscope and compared with the corresponding measurement obtained from a concomitant chest radiograph. The measured values did not differ significantly and in 18 out of 20 patients the accuracy was within 2 cm. No adverse effects were observed. We conclude that verification of tracheal tube position by fibre-optic bronchoscopy is a safe alternative to chest X-ray.

Bronchoscopy↗
PubMed1991

Neurogenic pulmonary edema: treatment with dobutamine.

In the case of a patient with complicating subarachnoid hemorrhage, an infusion of dobutamine was followed by a massive diuresis and regression of severe neurogenic pulmonary edema. It is suggested that the reduction in total peripheral vascular resistance and the increase in cardiac contractility accounts for the observed beneficial effect and indicate that dobutamine is a suitable drug for the treatment of neurogenic pulmonary edema.

Dobutamine↗