Studies on the Neutralizing Effects of Protamine on Unfractionated and Low Molecular Weight Heparin (Fragmin®) at the Site of Activation of the Coagulation System in Man

In a double-blind, randomized, cross-over study the neutralizing action of protamine towards unfractionated heparin (UFH, 150 U/kg i.v.) and a low molecular weight heparin (LMWH, Fragmin®, 100 anti-Xa U/kg i.v.) was investigated in 15 healthy subjects in vitro by measuring activated partial thromboplastin time (APTT), thrombin time (TT) and anti factor Xa activity (anti-Xa) in venous blood and in vivo by determination of prothrombin fragment 1.2 (f1.2) and thrombin-antithrombin III complexes (TAT) in venous blood and in shed blood. UFH and LMWH caused a prolongation of APTT and TT, an increase in anti-Xa and significantly inhibited f1.2 and TAT formation in shed blood, whereas only a minimal effect on TAT and f1.2 formation in venous blood was noted. Administration of 1 mg protamine/100 U UFH resulted in a near complete reversal of APTT, TT and anti-Xa, whereas lower doses (0.25 and 0.5 mg) were less effective. The effects of UFH on f1.2 and TAT generation in shed blood were partially (60-70%) neutralized only by the high dose (1.0 mg). Application of 1 mg protamine/100 anti-Xa U LMWH caused a near complete reversal of both APTT and TT but had only a weak effect on anti-Xa. In shed blood, the effect of LMWH on TAT and f1.2 formation was reversed by protamine only by 14% and 23% respectively. Our data do not support the concept that to reduce the incidence of protamine’s potential clinical side effects, the administration of a lower dose of protamine than 1 mg protamine/100 U UFH is justified. Furthermore, a significant residual impairment of hemostasis is still detectable after administration of the recommended dose of protamine to neutralize the anticoagulant effects of a LMWH preparation.

Measurement of extracellular fluid carboplatin kinetics in melanoma metastases with microdialysis

Clinical anti-tumour efficacy of anti-cancer drugs is a function of dose intensity, i.e. the concentration--time profile in tumour tissue. Hence, information on drug concentration profiles in tumours is of critical importance but appropriate methods for measurement are lacking. The aim of the present study was to obtain, by microdialysis sampling, concentration--time profiles in a solid tumour (melanoma) of a model anti-cancer drug, carboplatin, and thereby to assess the scope of microdialysis for tumour pharmacokinetic studies in man. Six patients with cutaneous melanoma metastases at the extremities or body trunk, scheduled to receive carboplatin (400 mg m-2 i.v.) were studied. Carboplatin concentrations were monitored in serum, intratumoral and subcutaneous tissue. Calibration of the microdialysis probes was carried out in vitro and in vivo with use of the retrodialysis method. Complete carboplatin concentration vs time profiles in tumour and subcutaneous tissue were obtained. Major pharmacokinetic parameters (maximum concentration, time to maximum concentration, area under the curve, elimination half-life) were calculated for tissues and tumour/serum concentration ratios for carboplatin were derived. Mean free concentrations of carboplatin in cutaneous melanoma metastases reached only about 50-60% of total serum levels; maximal intratumoral concentrations were 7.6 (+/-2.0; s.e.m.) microgram/ml, mean concentrations in subcutaneous tissue were similar to those in tumour. The present study demonstrates that microdialysis is a novel tool for measuring drug concentrations in solid tumours in humans in vivo and appears to be a valuable addition for pharmacokinetic/pharmacodynamic studies in oncology.

The effect of hyperoxia and hypercapnia on fundus pulsations in the macular and optic disc region in healthy young men

The purpose of this study was to investigate the influence of hyperoxia and hypercapnia on fundus pulsations in the macular and optic disc region and determine a potential autoregulative capacity of the choroid under these conditions. In a randomized cross-over study 100% O2 and a mixture of 5% CO2 with air was inhaled for 10 min by ten healthy male volunteers on different study days. Fundus pulsations were measured with a recently described laser interferometer. These results were compared to changes in systemic haemodynamics and Doppler-sonographic measurements of the radial artery. The fundus pulsation amplitude significantly decreased during hyperoxia and significantly increased during hypercapnia. These effects on fundus pulsations were stronger in the optic disc region than in the macular region. The systemic parameters showed only minor changes. Hence the amplitudes of fundus pulsations measured during hyperoxia and hypercapnia are assumed to be a consequence of metabolic autoregulative mechanisms. This autoregulative capacity is greater in the optic disc region than in the macular region, implying that the fundus pulsation amplitude in the papilla is influenced by both the choroidal and the retinal circulation.

Key metabolite kinetics in human skeletal muscle during ischaemia and reperfusion: measurement by microdialysis

The tissue kinetics of key metabolites of ischaemic and postischaemic tissue damage were studied in the intercellular space of human skeletal muscle by microdialysis. In vivo microdialysis calibration experiments (n = 5) yielded the basal intercellular concentration of glucose in human skeletal muscle (3.6 +/- 0.6 mM; mean +/- SD). The corresponding mean plasma glucose concentration was 4.3 +/- 0.2 mM which was significantly higher. The time vs. concentration profiles of intercellular glucose (n = 7), lactate (n = 5), TxB2 (n = 6) and urea (n = 8) were characterized during a 20 min period of leg constriction. TxB2 increased exclusively during reperfusion in comparison to baseline (n = 6). Administration of 500 mg acetylsalicylic acid, 5-10 min after onset of ischaemia blunted TxB2-response to reperfusion (n = 4). It is concluded that intercellular muscle glucose concentration is less than that in plasma. Glucose uptake in skeletal muscle is rapid even under ischaemic conditions. Synthesis and release of TxB2 is not evident during ischaemia. TxB2 mediated reperfusion injury might be reduced by acetylsalicylic acid, even if administered after onset of ischaemia.

Studies on the neutralizing effects of protamine on unfractionated and low molecular weight heparin (Fragmin) at the site of activation of the coagulation system in man

In a double-blind, randomized, cross-over study the neutralizing action of protamine towards unfractionated heparin (UFH, 150 U/kg i.v.) and a low molecular weight heparin (LMWH, Fragmin, 100 anti-Xa U/kg i.v.) was investigated in 15 healthy subjects in vitro by measuring activated partial thromboplastin time (APTT), thrombin time (TT) and anti factor Xa activity (anti-Xa) in venous blood and in vivo by determination of prothrombin fragment 1.2 (f1.2) and thrombin-antithrombin III complexes (TAT) in venous blood and in shed blood. UFH and LMWH caused a prolongation of APTT and TT, an increase in anti-Xa and significantly inhibited f1.2 and TAT formation in shed blood, whereas only a minimal effect on TAT and f1.2 formation in venous blood was noted. Administration of 1 mg protamine/100 U UFH resulted in a near complete reversal of APTT, TT and anti-Xa, whereas lower doses (0.25 and 0.5 mg) were less effective. The effects of UFH on f1.2 and TAT generation in shed blood were partially (60-70%) neutralized only by the high dose (1.0 mg). Application of 1 mg protamine/100 anti-Xa U LMWH caused a near complete reversal of both APTT and TT but had only a weak effect on anti-Xa. In shed blood, the effect of LMWH on TAT and f1.2 formation was reversed by protamine only by 14% and 23% respectively. Our data do not support the concept that to reduce the incidence of protamine's potential clinical side effects, the administration of a lower dose of protamine than 1 mg protamine/100 U UFH is justified.(ABSTRACT TRUNCATED AT 250 WORDS)

[Blind nasotracheal intubation in the muscle-relaxed patient]

A modified method of blind nasal intubation, using a muscle relaxant, is described, which has been used in 100 patients with an efficacy of 96%. The risk of suboxygenation was overcome by withdrawing the tube to the epipharynx and ventilating the patient's lungs after each failure to insert the tube in the trachea. The blind nasotracheal intubation of a relaxed patient is to be considered, when orotracheal intubation will be difficult or impossible to achieve, because of anatomic abnormalities or pathologic conditions of the upper respiratory tract. The dangers and complications of the method are discussed.

[Concentration and memory impairment in the later postoperative phase]

Of the different psychic function disturbances which may occur during the postnarcotic phase, those showing symptom complexes with sensory, neurotic-emotional or psychotic reactions mostly diminish within some hours or a few days. On the other hand, a great many patients suffer from individual mental problems of which concentration and memory weaknesses are the main characteristics, sometimes outlasting the surgical operation by a number of weeks or even months. The results of a preliminary examination of 520 patients, recently released from surgical departments, confirmed that 30% suffered from prolonged memory disturbances. Of a control group of patients treated with local anesthesia only 6% of 69 persons questioned had been aware of such symptoms. In the consecutive analysis of 90 surgical patients, making use of psychometric test methods such as digit span, learn- and memory test (German abbreviation LGT1) and concentration test d2, no reduction of memory capacity could be ascertained. An additional questioning of these patients about subjectively experienced disturbances, in comparison with the preliminary examination, resulted in approximately identical statements. The aetiology of subjectively experienced impairment of memory and concentration during the later postoperative phase appears to be still insufficiently clarified, for which psychogenic factors must be taken in consideration.

[Phlebitogenicity of venous catheters of Vialon]

During three days 132 surgical patients with postoperative infusion treatment were checked on the frequency of venous reactions in the arms when catheters/cannulas of 4 different materials were used and the outcome compared. A significant result was obtained in connection with the I-cath catheter made of vialon (a polyurethanelike resin polymer) and the L-cath of polyurethane. Phlebitis was decreased to 27.3% resp. 24.2% - approximately half of its usual frequency - when I-cath of polyvinyl-chloride and FEP-teflon vasofix cannulas were applied (both 51.5%). The different predisposing factors of infusion phlebitis are under discussion.

[Lung function after thoracic trauma. A contribution to the assessment of late functional lesions (author's transl)]

Respiratory function was investigated in 32 patients not later then 5 years after thoracic trauma. Forced expiration curves (volume/time and flow/volume mode) and nitrogen washout methods (single breath, multiple breath) were used including blood gas analyzes and thorax-X-rays. The typical effect of chest injury is mild to moderate restriction, which was found in 72% of the patients. Usually all volumes (FVC, FRC, TC) are reduced. 5 patients had slight to moderate obstruction, which we do not consider to be immediate consequence of trauma. 12 patients had signs of ventilatory maldistribution, which can be explained by reduced FRC in more or less all cases and obstruction in the above mentioned 5 patients. Observation of two cases leads us to conclude that chest injury may initiate development of chronic respiratory disease and that such a disease may be aggravated by thoracic injury. Motivation, young age, quality of rehabilitation, dorsal location of fractured ribs may help to improve the pulmonary status of the patient, existing or developing chronic lung disease, smoking, old age, lateral localisation of fractured ribs with dislocation will hinder improvement.

[Central venous catheterization via the internal jugular vein (Rao's method) (author's transl)]

Central venous catheterization via the internal jugular vein was performed in 208 patients. The clavicle-orientated approach, as described by Rao in 1977, was employed. Apart from a higher incidence of failures, arterial punctures and misplacement of the catheter, as compared with other techniques, there were also 3 cases of pneumothorax (1.4 per cent) which were attributable to the proximity of the puncture site to the pleura. In 3 patients with considerable hypovolaemia venipuncture was successful at the first attempt. In view of these observations the technique cannot be regarded as suitable for routine purposes.

[The uterotropismus of halothane, chloroform or methoxyflurane in clinical use (author's transl)]

To perform episiotomy, 89 women after childbirth were anaesthetized with either halothane (50 patients), methoxyflurane (24 patients) or chloroform (15 patients). The activity of the uterus was registered tocodynamographically. To examine the alternate influence of narcotics and uterotonica, 57 patients were pre-medicated with sintocinon and methergin i.m. as a prophylaxis. The second group (32 patients) received no premedication to stimulate labor activity, however in 18 cases towards the end of narcosis oxytocin and methergin were given i.v. In addition to these examinations 5 vaginal deliveries were anaesthetised with halothane only. Concerning our own experimental study it can be observed: 1. The relaxative properties of halothane wich suppresses completly the activity of myometrium during the deep stages of anaesthesia are superior to chloroform and methoxyflurane. 2. More rapid relaxation of the uterus with halothane compared with chloroform and methoxyflurane. 3. After the use of halothane a quicker return of the activity of the uterus compared with chloroform and methoxyflurane. 4. The value of a prophylaxis with uterotonica can be demonstrated by a comparatively reduced slowing-down of labour-activity during anaesthesia. 5. In every one of the cases, an interuption of the labour-suppressing, caused by the anaesthesia, can be obtained by injecting intravenously oxytocin or methergin. 6. During vaginal delivery, compared to the post placentar phase, there is no need for higher concentrations of halothane to be used to suppress labour contractions. The discussion deals with the intensity of reduction of the uterus contraction caused by the above mentioned narcotics, the dangers of the atony of the uterus, and the indications and contra-indications of obstetrical anaesthesia with halothane or methoxyflurane.

[Suppression of concomitant thrombosis in central venous catheters (infraclavicular route) by salicylates (author's transl)]

The antithrombogenetic effects of salicylates (Colfarit) were studied to determine whether thrombosis due to the catheter could be reduced. 50 patients with vena-cavacatheters (infraclavicular route) were examined by phlebography. 25 patients received no antithrombotic medications and served as the control group. In these cases 35% showed evidence of thrombus formation. The remaining 25 patients received salicylates. By this measure catheter-induced thrombosis was reduced by 67%.