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Biomedical subjects

L Kirkegaard

Publications and source records attributed to L Kirkegaard.

At least 19 recordsLinked to original sources
PubMed1999

Intestinal adsorption of levothyroxine by antacids and laxatives: case stories and in vitro experiments.

Two patients with hypothyroidism treated for upper dyspepsia and constipation with aluminum hydroxide and magnesium oxide, respectively, presented a marked increase in the serum concentration of thyroid stimulating hormone and low serum thyroxine on a fixed dosage of levothyroxine. After discontinuation of antacids/laxatives, thyroid stimulating hormone was again reduced indicating interaction between levothyroxine and antacids/laxatives. In vitro studies revealed a dose-related increased adsorption of levothyroxine by addition of a combination of aluminum hydroxide, magnesium hydroxide and magnesium carbonate, while no connection between levothyroxine and the addition of magnesium oxide, alone, was found. This finding has major clinical consequences since 1) many patients are treated with levothyroxine, 2) most patients do not tell physicians that they take antacids/laxatives, and 3) consumption of antacids/laxatives in patients with levothyroxine-treated hypothyroidism may lead to serious undersubstitution with levothyroxine.

Adsorption↗
PubMed1998

[Artifical respiration with patient in prone position].

The use of mechanical ventilation in prone position was proposed 20 years ago. Since then several investigations have been made trying to explain the mechanism whereby oxygenation is improved when the patient with ARDS is turned into the prone position. In supine position the lung perfusion is highest in the dorsal regions in normal healthy persons. However, when patients with ARDS are turned prone, the predominant dorsal perfusion is partly preserved, while at the same time the dorsal atelectases partly resolve, thereby improving the ventilation/perfusion ratio. Sixty-five percent of patients with early ARDS will achieve significant improvement in oxygenation in prone position. It is recommended that patients with early ARDS that remain hypoxic on mechanical ventilation with PEEP and inspiratory oxygen concentration above 60% be turned prone for 3-6 hours. If effective, the treatment can be repeated once or twice daily until regression of hypoxia. The possible effects of the prone position in other types of acute lung failure are so far not known.

Animals↗
PubMed1998

[Patients with acute respiratory distress syndrome mechanically ventilated in prone position].

Animal experiments and human studies have shown better oxygenation in mechanically ventilated patients with ARDS when the patient is situated in the prone position. In contradiction to former theories of a gravitational gradient of lung perfusion, a number of investigators have found that lung perfusion is preferentially distributed to the dorsal lung regions regardless of body position. The basal atelectasis and oedema in ARDS are resolved and only partly distributed anteriorly in the prone position, and these areas are thereby better ventilated. The combination of better ventilation and unchanged perfusion improves the ventilation/perfusion ratio and decreases the shunt in the prone position. In two cases of prone position in mechanically ventilated patients the PaO2/FiO2 ratio increased from 7.5 to 14.3 and from 8.8 to 19.8 after one hour in the prone position, and some of the improvement was permanent. Prone position has only minor side effects and is recommended as the first choice amongst adjunct therapies in mechanical ventilation in patients with ARDS remaining hypoxic in conventional therapy in the supine position.

Acute Disease↗
PubMed1994

[Midazolam and lorazepam as premedication. A randomized double-blind study].

Oral administration of midazolam and lorazepam as premedication was compared in a double-blind randomized clinical trial. Eighty patients scheduled for minor gynaecological surgery in general anaesthesia and 80 patients scheduled for hip arthroplasty in spinal anaesthesia were included. Assessments were: 1. patients subjective evaluation of the premedication, 2. sedation scale, 3. recovery of cognitive function assessed by Simple Paper-and-Pencil test and Postbox test, 4. amnesic effects. In the general anaesthesia group midazolam caused less postoperative sedation, less postoperative amnesia and cognitive function returned more rapidly. In the spinal anaesthesia group cognitive function returned more rapidly after midazolam. Midazolam should be preferred for premedication if rapid recovery is desired.

Administration, Oral↗
PubMed1990

[Conjunctival oxygen tension. Testing oxygen tension measurement of the conjunctiva].

A new apparatus which can measure oxygen tension and temperature in the conjunctiva was tested and compared with measurements of transcutaneous and arterial oxygen tension in eight volunteers in connection with normal oxygen tension, hypoxia and hyperoxia. In hypoxia, the conjunctival oxygen tension was found to be better correlated to and in better agreement with arterial oxygen tension than transcutaneous oxygen tension. The advantages with conjunctival oxygen measurements are continuous measurements in easily accessible and well vascularized tissue with the same arterial supply as the brain. In contrast to transcutaneous measurement, the new method does not require warming of the tissue as the conjunctiva is oxygen permeable.

Blood Gas Analysis↗
PubMed1990

Tissue oxygen tension measurement for monitoring musculocutaneous and cutaneous flaps.

In pigs, latissimus dorsi musculocutaneous island flaps and buttock skin island flaps were raised. Subcutaneous (PscO2) and intramuscular oxygen tension (PimO2) were measured using a non-heated needle electrode before, during and after repeated occlusion of the supplying artery or the draining vein. During arterial and venous occlusion, the tissue oxygen tension in the musculocutaneous flap dropped rapidly. A plateau was reached after 15 min. After arterial occlusion the mean value was 20 mmHg (SEM = +/- 5 mmHg, N = 6) in the subcutis and 16 mmHg in the muscle (SEM = +/- 4 mmHg, N = 10). After venous occlusion the mean value was 11 mmHg (SEM = +/- 3 mmHg, N = 6) in the subcutis. In the skin flap the drop of PscO2 was slower, and after 30 min of arterial occlusion the mean value was 29 mmHg (SEM = +/- 9 mmHg, N = 6). This study has shown that tissue oxygen tension measurement can be used as a sensitive indicator of acute impairment of the supplying vessels in island flaps. The method seems to have potential for monitoring free tissue transfers. A comparable decrease in PscO2 was found for arterial and venous impairment.

Animals↗
PubMed1989

Effect of hemorrhage and resuscitation on subcutaneous, conjunctival, and transcutaneous oxygen tension in relation to hemodynamic variables.

Subcutaneous (PscO2), conjunctival (PcjO2), and transcutaneous (PtcO2) oxygen tension values were measured in anesthetized dogs subjected sequentially to hemorrhage and reinfusion of the shed blood. Intravascular pressure, hemodynamic variables, and oxygen transport variables were measured simultaneously. During hemorrhage, PscO2 was the first of the PO2 measurements, and among the first set of hemodynamic variables that differed significantly from control values. During continuous bleeding, PscO2 and PcjO2 fell rapidly, the decline of PscO2 and PcjO2 was similar and significantly higher than that found for PtcO2. After reinfusion of shed blood, PscO2 was the last of PO2 measurements, and among the last set of hemodynamic variables, to return to control values. While PaO2 remained constant, PvO2 decreased significantly during hemorrhage and normalized during resuscitation. Unheated instruments for measuring PscO2 and PcjO2 are reliable indicators of peripheral perfusion during hemorrhage and resuscitation. Subcutaneous oxygen monitoring, in particular, seems capable of assessing early blood loss and adequacy of resuscitation after acute hemorrhage, and may be clinically useful.

Animals↗
PubMed1989

Flumazenil used for antagonizing the central effects of midazolam and diazepam in outpatients.

In a double-blind, randomized trial, the efficacy and safety of flumazenil, a benzodiazepine antagonist, was evaluated in patients after gastroscopy under midazolam or diazepam sedation. The criteria of efficacy were the degree of sedation and anterograde amnesia. Flumazenil significantly reduced the degree of sedation in both groups without significant intergroup differences. No sign of resedation was found during the observation period of 3 h. The anterograde amnesia was effectively antagonized in both groups. Flumazenil was well tolerated. Flumazenil is a safe and effective benzodiazepine antagonist which makes it possible to reduce the recovery period in outpatients sedated sufficiently with benzodiazepines for gastroscopy.

Adult↗
PubMed1988

Continuous monitoring of tissue oxygen tension during hyperoxia and hypoxia: relation of subcutaneous, transcutaneous, and conjunctival oxygen tension to hemodynamic variables.

Subcutaneous, transcutaneous, and conjunctival oxygen tensions (PscO2, PtcO2, and PcjO2, respectively) were measured in anesthetized dogs subjected sequentially to normoxia, hyperoxia, and hypoxia. Intravascular pressure, hemodynamic and oxygen transport variables were measured simultaneously. PtcO2 and PcjO2 closely paralleled PaO2 during normoxia, hyperoxia, and hypoxia over a wide range of arterial oxygen tensions. PtcO2 was reliable over the widest range of PaO2, with a correlation coefficient of .94. The PcjO2/PaO2 index fell at very low PaO2. The PscO2/PaO2 index decreased at both very low and very high PaO2. Only minor changes were found in hemodynamic and oxygen transport variables during hyperoxia. During hypoxia, however, cardiac output and other central hemodynamic measurements increased, while PscO2, PtcO2, and PcjO2 fell. Oxygen delivery and oxygen consumption were maintained or only slightly changed during hypoxia. All three continuous measurements of oxygen tension are reliable indices of PaO2 over a wide range under normovolemic conditions. The instruments for measuring PscO2 and PcjO2 are unheated and therefore may have advantages for human application.

Animals↗
PubMed1988

Benzodiazepine intoxication treated with flumazenil (Anexate, RO 15-1788).

The efficacy and safety of flumazenil were assessed in comparison to placebo in a double-blind randomised study of 31 adults intoxicated with benzodiazepines. The criteria of efficacy were the degree of sedation, and orientation in time and space. Patients who received flumazenil awoke within minutes but central depression returned partly one hour later, which reflects the short elimination half-life of the drug. Side effects were few and the results indicate that flumazenil is effective in the primary management of benzodiazepine overdose and in states where benzodiazepines have been taken with other drugs.

Adolescent↗
PubMed1988

Flumazenil used in the antagonizing of diazepam and midazolam sedation in out-patients undergoing gastroscopy.

In two double-blind, randomized trials the efficacy and safety of flumazenil, the first benzodiazepine antagonist, were assessed in 100 adult patients undergoing gastroscopy under diazepam or midazolam sedation. The criteria of efficacy were the degree of sedation and anterograde amnesia. The median gastroscopy time was 20 min (range 5-40 min). The diazepam group received median 30 mg (range 15-60 mg) Diazemuls and the midazolam group median 15 mg (range 10-40 mg) Dormicum. Both groups were antagonized by median 0.42 mg flumazenil (range 0.4-0.6 mg). There was no inter-group difference with regard to blood pressure, heart rate and respiration rate. There was a significantly faster recovery of the patients after injection of flumazenil than after placebo. Patients were awake shortly after flumazenil, but remained drowsy or asleep after placebo administration. All patients, regardless of diazepam or midazolam sedation, antagonized with flumazenil were awake within 5 min and remained awake during the whole observation period of 3 h. The amnesia was totally eliminated by flumazenil. There were no significant differences in side-effects between the groups.

Adolescent↗
PubMed1987

Randomized clinical investigation of Ro 15-1788, a benzodiazepine antagonist, in reversing the central effects of flunitrazepam.

In a double-blind, randomized study the efficacy of Ro 15-1788 as a benzodiazepine antagonist was evaluated in patients anaesthetized with flunitrazepam. The effects were compared with a comparable group of patients who did not receive the antagonist. Ro 15-1788 significantly reversed the sedative and hypnotic effects of flunitrazepam and reduced the degree of anterograde amnesia. No side-effects were attributable to the drug.

Adjuvants, Anesthesia↗
PubMed1987

[Effect of thiopental Na on the concentration of calcium ions in blood].

The hemodynamic effects induced by thiopental and a decrease in blood ionized calcium are uniform. This investigation was undertaken to show a possible decrease in ionized blood calcium during induction of general anesthesia with thiopental. Twenty-four patients aged 19-79 years (median 57) were studied. None had any known parathyroid disease, malabsorption, or chronic renal insufficiency, and none were receiving calcium channel blockers. For the analysis of blood Ca++, pH, and PCO2, blood samples were drawn anaerobically into a heparinized syringe from an i.v. cannula. A special heparin solution was used (S4500 Radiometer, Copenhagen) to avoid the influence of heparin on the Ca++ determination. The initial 2 ml were discarded. No samples were drawn in the first 3 min after removal of the tourniquet. A maximum of 100 ml isotonic saline was infused between the two samplings. The infusion was stopped for at least 30 s before sampling. PCO2, B-Ca++, and pH were measured directly using the ABL 4 (Radiometer, Copenhagen) and the ICA 1 ionized calcium analyzer (Radiometer, Copenhagen). The standard deviation of repeated measurements of B-Ca++ within a short time using the same sample is 0.01 mmol/l on the ICA 1. The samples were drawn just before and 2 min after thiopental injection (median 5.9 mg/kg) was started. The pulse and blood pressure were simultaneously measured. The individual Ca++ measurements are shown in Table 1. The results of the investigation are shown in Table 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗