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Biomedical subjects

H Renck

Publications and source records attributed to H Renck.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effects of adjuvants to local anaesthetics on their duration. II. Studies of some substituted dextrans and other macromolecules in rat infraorbital nerve block.

The effects of adding various macromolecular substances to 2% prilocaine on duration of rat infraorbital nerve block were investigated. The tested substances consisted of dextrans with lipophilic or charged substituents as well as other neutral or highly charged macromolecules. Most of the adjuvants caused significant prolongations of sensory block. For substituted dextrans the duration of sensory block degree 3 amounted to between 120% (3% capryldextran II) and 350% (3% carboxymethyldextran) in comparison to prilocaine plain. The corresponding values for hydroxypropylstarch (3%) alginic acid (0.5%), beta-cyclodextrin (1.5%) and hyaluronic acid (0.25%) were about 170%, 285% and 380%, respectively. The results suggest that the increased duration of local analgesia by prilocaine is related to increased viscosity of the solution produced by the macromolecular compounds. The mechanism seems to be of a physical character, and hyaluronic acid seems to be worthy of further studies.

Alginates↗
PubMed1985

Effects of adjuvants to local anaesthetics on their duration. III. Experimental studies of hyaluronic acid.

The effects of addition of hyaluronic acid (sodium hyaluronate, Healon) to different local anaesthetics of the amide type on the duration of sensory or motor blocks following various regional anaesthetic procedures were studied in animal experiments. In the rat infra-orbital nerve block model, the addition of 0.1-0.5% hyaluronic acid (HA) to 2% prilocaine increased the duration of sensory block of varying degrees in a dose-dependent way by up to 500% of values obtained with plain prilocaine. The duration of degree 5 blocks produced by 0.5% etidocaine and 0.5% bupivacaine was also significantly prolonged when 0.4% HA was included to 206% and 282% of control, respectively, while blocks induced by 2% lidocaine were prolonged to 123% of control. The duration of motor block following spinal anaesthesia in the mouse was prolonged in a dose-dependent way when HA was added to prilocaine, bupivacaine and etidocaine. For solutions containing 0.4% HA, prolongations to 254%, 166% and 134% of control, respectively, were obtained. A concomitant increase of latency to onset of block and failure rate occurred with increasing concentrations of HA. The duration of corneal anaesthesia in the rabbit increased by 57% and 44% when 0.3% HA was added to prilocaine and bupivacaine, respectively. The duration of infiltration anaesthesia was not affected by the addition of HA to the local anaesthetic solutions. Addition of HA had no effect on the onset, depth and duration of prilocaine-induced block of the nervous transmission in vitro. The duration of infra-orbital nerve block and spinal anaesthesia shows a significant relation to the relative viscosity of the local anaesthetic solution.

Anesthetics, Local↗
PubMed1985

Multiple intercostal blocks by a single injection? A clinical and radiological investigation.

Three different techniques for producing multiple intercostal nerve blocks using bupivacaine were compared in volunteers. The techniques used were multiple injections at intercostal nerves 7-11, or a single injection employing a needle or a catheter inserted in the 9th intercostal space. The injections were made at the costal angle. The anatomical spread of a mixture of a local anaesthetic and a radio-opaque fluid following the single injection technique at the ninth intercostal space or at the subcostal space was evaluated by computerized x-ray tomography (CT). The distribution of cutaneous analgesia/hypalgesia following all techniques was evaluated by pin prick. No spread of the local anaesthetic to adjacent intercostal spaces or to the paravertebral space could be shown by CT. The distribution of cutaneous analgesia was limited to three segments or less following a single injection. No difference in blood levels of bupivacaine could be found. It is concluded that the single injection technique of producing multiple intercostal nerve blocks is inferior to the multiple injection technique.

Adult↗
PubMed1985

Effects of adjuvants to local anaesthetics on their duration. IV. Effect of hyaluronic acid added to bupivacaine or prilocaine on the duration of nerve blockade in man.

A randomized study of the duration of ulnar nerve blockade induced with 2% prilocaine or 0.5% bupivacaine with and without 0.4% hyaluronic acid was performed in volunteers. In contrast to results in experimental animals, the addition of hyaluronic acid to the local anaesthetic solution did not affect the duration of sensory nerve block.

Adjuvants, Anesthesia↗
PubMed1984

Fetal circulation during epidural analgesia for caesarean section.

Fetal blood flow was examined during epidural analgesia in six women with uncomplicated pregnancies undergoing elective caesarean section. A non-invasive, ultrasonic technique was used to measure blood flow in the fetal descending aorta and intra-abdominal part of the umbilical vein before induction of analgesia with etidocaine and bupivacaine and 15 and 30 minutes afterwards. No appreciable change in fetal blood flow was observed.

Adult↗
PubMed1983

Adverse reactions to dextran in Sweden 1970-1979.

In a retrospective investigation of the period 1970-1979, 478 reports on cases of dextran-induced anaphylactoid/anaphylactic reactions (DIAR) were found. In 458 of these dextran was judged to be the causative agent. The number of units of dextran 40 and 70 used during this decade was 313 598 and 1 051 668, respectively. During the last five years, when reporting of severe adverse drug reactions was mandatory, the incidence of severe DIAR per unit administered was 0.013% for dextran 40 and 0.025% for dextran 70. The incidence of fatal DIAR was 0.003% and 0.004%, respectively. We found a male: female ratio of 1.5: 1 for all DIAR while for the most severe DIAR this ratio was 3: 1. The mean age of the patients was higher in severe than in mild DIAR. Allergic disease did not predispose for severe DIAR. Diabetes, cardiovascular and pulmonary diseases and chronic inflammation were more frequent among the patients who had suffered the most severe DIAR. 22 reactions were characterized by fever and/or shivering, and in 19 of these cases the reaction occurred after infusion of more than one unit of dextran. Severe DIAR occur after infusion of a few ml of dextran. Fatal DIAR during anaesthesia occurred almost exclusively in patients under spinal or epidural blockade. A favourable outcome of resuscitation in DIAR with cardiac arrest was possibly promoted by the infusion of large amounts of crystalloid fluids. We could not show that therapy with steroids, epinephrine or isoprenaline influenced the outcome. Fatal DIAR occurred even after infusion of only 0.5-1 ml of dextran, and we strongly advise against the use of "biological test-doses".

Aged↗
PubMed1983

Prevention of dextran-induced anaphylactic reactions by hapten inhibition. I. A Scandinavian multicenter study on the effects of 10 ml dextran 1, 15% administered before dextran 70 or dextran 40.

In an open prospective study the prevention of dextran-induced anaphylactic reactions (DIAR) by hapten inhibition was investigated in 29 252 patients. Forty-nine hospitals in Sweden, Norway and Finland participated in the study which was running for two years. Ten ml of dextran 1, 15%, (Promiten, Pharmacia AB, Uppsala, Sweden) with a weight average molecular weight of 1 000 dalton was injected intravenously two minutes before infusion of dextran 70 (Macrodex) or dextran 40 (Rheomacrodex). DIAR were graded according to severity from I to V. Six grade III and one grade IV reactions occurred, representing an incidence of severe DIAR of 0.024%. Compared to a large historical control material, preinjection of 10 ml of dextran 1 exerts a partially protective effect, but no statistical proof can be given. Consequently trials have been started with a 20 ml dose of dextran 1. Adverse reactions to the preinjection of 10 ml of dextran 1 were observed in 0.072%. These reactions were of a mild and shortlasting nature and considered to be of minor clinical importance.

Adolescent↗
PubMed1983

Prevention of dextran-induced anaphylactic reactions by hapten inhibition. II. A comparison of the effects of 20 ml dextran 1, 15%, administered either admixed to or before dextran 70 or dextran 40.

The incidence of dextran-induced anaphylactoid/anaphylactic reactions (DIAR) was investigated after hapten inhibition employing two different modes of administration of dextran 1 (Mw 1 000 dalton). The trial was carried out as an open prospective study that comprised 12 060 patients. They were randomized into two groups--one receiving a mixture of 20 ml dextran 1, 15%, (Promiten) and 500 ml dextran 70 (Macrodex) or dextran 40 (Rheomacrodex) (admixture group), the other receiving an intravenous injection of 20 ml dextran 1, 15% before the infusion of dextran 70 or 40 (preinjection group). DIAR were graded according to severity from I to V. In the admixture group eight DIAR of grade II, one of grade IV and one of grade V were observed, while in the preinjection group two DIAR of grade II occurred. The admixture of dextran 1 to dextran 70 or 40 does not prevent the occurrence of severe DIAR in the dose investigated.

Adolescent↗
PubMed1983

Prevention of dextran-induced anaphylactic reactions by hapten inhibition. III. A Scandinavian multicenter study on the effects of 20 ml dextran 1, 15%, administered before dextran 70 or dextran 40.

In an open, prospective multi-center study prevention of dextran-induced anaphylactic reactions (DIAR) was attempted by intravenous injection of 20 ml dextran 1, 15%, Mw 1000 dalton, (Promiten), two minutes before start of infusion of dextran 70 (Macrodex) or dextran 40 (Rheomacrodex). Of 34955 patients investigated, only one developed a severe DIAR of grade III (0.003%). The incidence of severe DIAR after preinjection of 20 ml dextran 1 is significantly lower than that after injection of 10 ml dextran 1 (p = 0.01), and is also markedly lower than that of a large Swedish historical control material (0.037-0.050%). The incidence of mild DIAR is not affected by dextran 1. Adverse reactions to dextran 1 of a generally mild and short-lasting nature were observed in 20 patients. It is recommended that patients who are going to receive dextran 70 or 40 are given a prophylactic i.v. injection of 20 ml dextran 1 before the first unit of clinical dextran to minimize the risk of severe DIAR.

Adolescent↗
PubMed1980

Formation of acetaldehyde from diethyl ether in man.

Diethyl ether anaesthesia caused detectable blood acetaldehyde levels in 15 patients. The average acetaldehyde concentration was 21 micro M which approximates the level found after intake of ethanol. No acetaldehyde could be found in patients anaesthetised without ether.

Acetaldehyde↗
PubMed1980

Incidence, pathomechanism and prevention of dextran-induced anaphylactoid / anaphylactic reactions in man.

The symptoms of dextran-induced anaphylactoid/anaphylactic reactions (DIAR) range from skin reactions to severe circulatory shock (severity grades I-IV). The reported incidence of DIAR varies between 0.03% and 4.7%, severe reactions comprising 0.008% and 0.6% resp. Studies to elucidate the pathomechanism of DIAR and to possibly prevent them were made during the last decade: No evidence for a pathogenic role of contaminating macromolecules was found, but the dextran molecule itself could be incriminated as elicitor agent. High titres of dextran reactive antibodies (DRA) of predominantly IgG class are regularly found in sera of patients with grade III+IV reactions. Such DRA reflect immunization with dextran cross-reactive bacterial polysaccharides or native dextran. No DRA of IgE class were found. Presence of high IgG-DRA levels, reduction of complement factor Clq and histopathological findings in lungs, all indicate that DIAR should be classified as aggregate (immune complex) anaphylaxis. Hapten inhibition was therefore proposed to prevent DIAR. Based on positive results in animal models, clinical trials were started 1978. Hitherto, 60 485 patients have been studied. It is concluded that the combined use of preinjection of 20 ml Dextran 1 (Pharmacia AB, Uppsala, Sweden) and infusion of Macrodex or Rheomacrodex improves the safety of dextran administration.

Anaphylaxis↗
PubMed1979

Circulating tissue thromboplastin during hip surgery.

An immunoradiometric assay for tissue thromboplastin has been established. Blood levels in 6 patients undergoing total hip replacement have been determined. In 3 patients, high levels of circulating apoprotein III were found at various stages of the operation, showing a release of tissue thromboplastin chiefly during impaction of the prosthesis into the femoral bone. The other 3 patients had low or undetectable levels.

Adult↗
PubMed1978

Cardiac effects of thoracic epidural analgesia before and during acute coronary artery occlusion in open-chest dogs.

The effects of thoracic epidural analgesia (TEA) on myocardial performance and metabolism and on the severity of an acute myocardial ischaemia, were studied in eight anesthetized open-chest dogs. TEA reduced mean arterial blood pressure (AP) by 26%, heart rate (HR) by 20%, left ventricular dP/dt by 37%, and myocardial oxygen consumption by 27%. Although arterial concentrations of free fatty acids, glucose and lactate were unchanged, their myocardial uptake was reduced in proportion to the reduction in mechanical activity of the heart. Acute ischaemic injury was estimated from epicardial ECG recordings 10 min after occlusion of a branch of the left anterior descending coronary artery. In seven of eight dogs TEA caused a substantial reduction in the severity of the acute myocardial ischaemic injury. In the eight dogs investigated, the sum of ST segment elevations in epicardial ECG recordings was reduced from 34.0 +/- 3.4 to 23.3 +/- 2.8 mV (mean +/- SEM, P less than 0.01). After restoration of AP and HR to control values with phenylephrine and atrial pacing, the favourable effect of TEA on myocardial ischaemic injury was abolished. It is concluded that TEA effected a reduction in the severity of myocardial ischaemia in open-chest dogs, mainly through reduction of myocardial mechanical activity with consequent reduction of myocardial metabolism.

Anesthesia, Epidural↗
PubMed1978

Unusual response to extradural analgesia in the presence of an intradural spinal tumour.

A patient is presented in whom indications of the presence of an intradural, extramedullary tumour became apparent during the induction of an extradural block. It is suggested that a combination of signs should arouse suspicions of such a tumour close to the puncture site. Pain within an area covered by an extradural block does not indicate necessarily a supraspinal cause for the pain.

Anesthesia, Epidural↗
PubMed1978

Cardiovascular effects of epidural analgesia. I. Thoracic epidural analgesia. An experimental study in sheep of the effects on central circulation, regional perfusion and myocardial performance during normoxia, hypoxia and isoproterenol administration.

Some circulatory effects of thoracic epidural analgesia (TEA) were investigated in splenectomized, open-chest sheep during normoxia, hypoxia and isoproterenol administration. During normoxia, TEA caused comparatively marked reductions in systemic arterial blood pressure, total peripheral resistance and cardiac output. A fall in heart rate was not compensated for by any rise in stroke volume. Myocardial contractility (LV dd/dt/IP) was not affected by TEA. The proportion of cardiac output diverted to the blocked area was markedly increased. Compensatory vasoconstriction was not observed within the unblocked area in six out of nine animals. Myocardial blood flow showed a pronounced reduction in accordance with the calculated changes of heart work, so that myocardial oxygen extraction remained unchanged. Studies under hypoxia revealed that cardiac responses to hypoxia in the sheep are mediated chiefly by neurogenic factors. TEA abolished the hypoxia-induced rise in heart rate but did not affect the increase in pulmonary vascular resistance caused by hypoxia. The administration of isoproterenol during TEA increased systemic arterial blood pressure, but due to further fall in total peripheral resistance it was not fully normalized. Cardiac output and heart rate increased markedly. Myocardial oxygen consumption and blood flow increased but did not reach control levels.

Anesthesia, Epidural↗