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Biomedical subjects

W Dick

Publications and source records attributed to W Dick.

At least 217 records · Page 12Linked to original sources
PubMed1984

Investigation of intrapartum clearance of the upper airway in the presence of meconium contaminated amniotic fluid using an animal model.

In order to define as effective a procedure as possible for the intra- and post-partum clearance of the upper airways of meconium contaminated infants, three methods of suction clearance, nasal, oral and combined nasal and oral, were carried out on each of five kittens aged between 17 to 19 weeks. There was an interval of at least one week between each investigation. The animals were anaesthetized with ketamine intramuscularly. The pressure changes during delivery were simulated using a compressed blood pressure cuff around the kittens thorax. During the first minute of thoracic compression Tc 99 labeled synthetic sputum was introduced into both the oro- and nasopharynx, then during the 2nd minute the instilled fluid was removed using a conventional extractor with mucus trap. Solely oral or solely nasal routes were used, suction was carried out for 60 secs, whereas when the combined technique was applied the oral and nasal cavities were cleared for only 30 secs each. At the end at the 2nd minute thoracic compression was released and a deep inspiration occurred. After five minutes the radioactivity remaining after suction was documented using a gamma-camera. We attempted to answer the following questions: How much mucus could be extracted with each different method, and where the remaining amount was later distributed? Nasal suction alone was found to be inefficient; using this route an average of 13% (only an eight of the amount instilled) could be removed. Oral suction led to the recovery of an average of 52% of the material instilled, the combined technique much as 56%. After re-establishment of spontaneous respiration, it could be clearly seen that, independent of the efficacy of the technique used, the majority of the remaining radioactivity (55 relative percent) is localized in the head and neck area. Absolute values are 45% for nasal suction, 26% for oral, and 24% for the combined oro-nasal route. The other part of the remaining radioactivity was found in the lung or in the stomach. It must be pointed out that the aspirate need not be disturbed in both of the parts, both the stomach and the lungs can be solely involved. Five minutes after spontaneous respiration had been resumed the lungs revealed only a centrally distributed radioactivity. This corresponds anatomically to the trachea and major bronchi. The peripheral area of the lungs was free of aspirate at this point in time.(ABSTRACT TRUNCATED AT 400 WORDS)

Airway Obstruction↗
PubMed1984

[Induction of beta-lactamases in Enterobacter cloacae with beta-lactam antibiotics].

The induction potency of various beta-lactam compounds was studied in a clinical isolate which exhibited resistance against most beta-lactam compounds; however, spontaneous beta-lactamase production was only marginal in this strain. In general, all beta-lactam derivatives included in this study possessed induction potency independent of the nucleus of the compound. N-formimidoyl thienamycin, the penem compound Sch 29482, 6-aminopenicillanic acid, and clavulanic acid proved to be the most potent inducers. With the exception of mezlocillin and ceftazidime there was a correlation between the concentration of the compound and the induction potency. Combination of two beta-lactam antibiotics resulted in an addition of the induction potency of each one. With respect to the considerable amount of enzyme that can be induced the development of resistance even against newer compounds fairly stable against the attack of beta-lactamases can be explained.

Anti-Bacterial Agents↗
PubMed1984

[Comparative studies on the side effects of morphine after peridural, spinal and intravenous administration].

A prospective randomized study was carried out on 29 patients undergoing transurethral prostatectomy. In addition to the regional anaesthetic given for the operation, the patients received either: 1 mg morphine intrathecally (spinal group), 0.05 mg/kg body weight of morphine i.v. (i.v. group), or 0.05 mg/kg body weight epidurally (PDA group). Two of the intrathecal group patients had to be given an antagonist because of clinically relevant respiratory depression. In one of these cases, this depression could be documented by a continuous fall in respiratory minute volume, and an increase in PCO2. In the other, bradypnoea and vomiting developed within a few minutes of injection. The presence of a central action of intrathecal and epidural opiates was indicated by the significant increase in reaction time found. In the two instances of respiratory depression, the CSF morphine concentration 24 hrs after injection was markedly lower (0 and 18 ng/ml respectively) than in unaffected patients. It must therefore be assumed that the respiratory depression was caused by a more rapid cephelad transport than that occurring in normal cases.

Aged↗
PubMed1984

[Abdominal compression and PEEP respiration during cardiopulmonary resuscitation].

Three different resuscitation techniques were assessed by monitoring haemodynamic, respiratory, and cerebral parameters in 12 pigs of average body wt. (29 kg) following electrically induced cardiac arrest. All three techniques were carried out in randomised sequence, each for ten minutes, on each of the 12 animals. I = interposed ventilation and thoracic compression; S = simultaneous ventilation and thoracic compression; SA = simultaneous ventilation and thoracic compression plus abdominal binding 100 mm Hg. A compression rate of 60/min and ventilation rate of 12 min were used for each of the three techniques. 6 animals were ventilated with ZEEP for the whole of the 30 min observation period, the remainder with a PEEP of 5 cm H2O. In both ZEEP and PEEP groups the highest blood pressure and carotid artery flow rates were observed with the "SA" technique. PEEP ventilation and abdominal binding was found to be the most effective combination. Despite a rise in intracranial pressure, cerebral perfusion pressure rose when abdominal binding was applied. The CO2-production and arterio-venous oxygen difference of both ventilation groups were not significantly influenced by the different techniques. Even the technique "SA" did not markedly influence gas exchange or acid-base parameters. Despite an increase in the arterial base deficit and lactate levels during the course of resuscitation, the arterial pH did not fall below initial values because of the low paCO2. The positive effect of abdominal binding is a result of increased intrathoracic pressure, an increase in the effective circulating blood volume, and redistribution of blood flow.

Abdomen↗
PubMed1984

[Comparative clinical studies on parenteral and oral premedication in childhood with special regard to the volume and acidity of the gastric juice].

90 children of age between 1 and 10 years who were scheduled for adenotomy were randomized into 3 premedication-groups. Group 1 received no premedication, group 2 chlorprothixene 1 mg/kg i.m. and group 3 chlorprothixene 2 mg/kg orally. Prior to induction of anaesthesia 63.3% of the unpremedicated children were anxious or crying, in contrast to 23.3% of the children given oral or i.m. premedication. With respect to the reaction on venepuncture with a Butterfly G 23, there was no significant difference between the groups. The volume of gastric acid (median values) was 0.056 ml/kg in group 1, 0.063 ml/kg in group 2, and 0.068 ml/kg in group 3, with a pH of 2.0, 1.5 and 2.0 respectively. One hour after operation 44.8% of the children in group 1, 92.6% in group 2 and 84.6% in group 3 were calm or sleeping. Premedication definitively improves the pre- and postoperative management of children. We now recommend oral chlorprothixene for the premedication of children because the effect of this oral premedication is equivalent to i.m. application, and the oral route has no influence on the quantity or acidity of gastric contents.

Adenoids↗
PubMed1984

[Comparative studies on general anesthesia versus peridural anesthesia in primary cesarean section].

In a prospective interdisciplinary study involving the departments of gynaecology, anaesthetics and paediatrics, the influence on both the mother and neonate of general as opposed to epidural anaesthesia was compared in 47 planned caesarean sections. Neither maternal or foetal risk factors were present in these cases, and the cardiotocogram was always normal before the anaesthetic was applied. Methods. Systolic and diastolic blood pressure were carefully monitored. Under an identical infusion regime the following parameters were estimated in maternal blood: blood gas and acid-base status, blood sugar, lactate, beta-hydroxybutyric acid, ACTH and cortisol. These same parameters were also estimated in cord blood taken at delivery. The Apgar score at 1, 5 and 10 minutes, and a complete paediatric assessment including neurostatus at 15 minutes, 24 hours and 7 days of age were used to assess neonatal status. Some of the women given a general anaesthetic initially had marked increases in blood pressure and pulse, while about a third of the epidural cases showed a blood pressure fall despite positioning in the left lateral position in order to prevent the aorto-caval syndrome. An increase in lactate, ACTH and cortisol was found in both groups up to the time of delivery, when the ACTH level of the general anaesthetic group was significantly higher. Acid-base and PCO2 values were not markedly influenced by either of the techniques used, but the maternal capillary PO2 levels were very much higher in the general anaesthetic group. The neonates born under general anaesthetic had a lower 1 min Apgar score, as a result of the relatively long induction-delivery time, of on average 17 min. The 5 and 10 min Apgar scores and the neurophysiological development of the babies revealed no differences between the two groups.

Adult↗
PubMed1984

[Catheter peridural anesthesia with bupivacaine HCI and bupivacaine CO2. A comparison and the effects of premedication].

A controlled prospective randomized study was carried out to compare the action of 0.5% bupivacaine-CO2 and 0.5% bupivacaine-HCI both with and without diazepam premedication. Those patients given an epidural with 0.5% bupivacaine-CO2 and diazepam premedication showed both the briefest time to onset of action and the greatest degree of motor block. In contrast to the other three groups, none of these patients had missed segments. Despite the fact that no significant differences could be calculated, the difference in intensity of action observed in this investigation may well be of clinical relevance.

Aged↗
PubMed1984

Does geographical location influence inflow requirements of the Bain breathing system?

A review of publications from various countries, using the Bain system with a fresh gas flow of 70 ml kg-1 min-1 and controlled ventilation, show a range of mean PaCO2 values between 36 and 43 mmHg. It was suggested that these differences could be related to the geographic location of the patient population studied. Anaesthetists from seven institutions in West Germany, England, Sweden, the United States, Australia and Canada collaborated in a preliminary study designed to find out whether these differences could be reduplicated. In 142 patients under a standard anaesthesia with controlled ventilation, PaCO2 values were determined 30 min after the fresh gas flows had been set. For 70 ml kg-1 min-1 the mean PaCO2 values ranged from 33 to 40 mmHg; for 100 ml kg-1 min-1 from 28 to 35 mmHg. Compared to the mean PaCO2 values from Canada, the results from Australia and the USA were not different and all at the lower end of this range; Sweden, West Germany and England reported significantly higher PaCO2 values. In the absence of any other obvious explanation, we suggest that patients in England and Northern Europe could have a higher CO2 output under anaesthesia than North American or Australian patients.

Adult↗
PubMed1984

[Intramuscular ketamine analgesia in emergency patients. II. Clinical study of traumatized patients].

Twenty traumatized patients suffering from burns, fractures and bruises were given either 0.5 mg/kg or 1.0 mg/kg ketamine intramuscularly for analgesia. Within 10 min effective analgesia was present in both groups. In the 1 mg/kg group analgesia was more intense, and of longer duration. The higher dose of ketamine led to an impairment in the level of consciousness. Some of the patients of this group were markedly desorientated. The highest plasma levels of ketamine were 147 ng/ml (median) in the 0.5 mg/kg group at 30 min and 474 ng/ml (median) in the 1.0 mg/kg group at 15 min. As to side-effects, 3 patients reported dizziness and 1 patient vomited. Intramuscular applications of 0.5 mg/kg ketamine affords a good but short lasting analgesia with few side-effects.

Adolescent↗
PubMed1984

[Animal experiment study on intracranial pressure, after ketamine administration].

The action of ketamine on intracranial pressure in the presence of haemorrhagic shock, at both the dosage levels used for emergency cases and for in-patient treatment, was investigated using an animal model. Haemodynamically stable animals with a normal or raised intracranial pressure served as a control group. All animals were normoventilated. No rise in intracranial pressure was observed with either 0.5 or 2.0 mg/kg body weight of ketamine in those animals with normal, or in those with a raised pressure. This applied to both the haemodynamically stable animals, and to those in haemorrhagic shock. This finding is probably due to the fact that PCO2 levels did not rise under the controlled ventilation.

Anesthesia, Intravenous↗
PubMed1983

The delayed use of positive end-expiratory pressure (PEEP) during respiratory resuscitation following near drowning with fresh or salt water.

Investigations on the delayed use of positive end-expiratory pressure (PEEP) following a standardized form of near drowning with 12.5 ml/kg body weight of either fresh or salt water were carried out on 14 anaesthetized and ventilated young pigs. After a 3-min period of apnoea the animals were ventilated with 100% oxygen and with either the same or an increased tidal volume, and a PEEP of 5 cmH2O delayed to 20 min, over a period of 2 h. In both fresh and salt water, initial values of PaO2 and AaDo2 were regained by the end of the period of observation when a delayed PEEP was applied. The intrapulmonary right to left shunt, which increased to 40% of the cardiac output, fell by a half within 10 min of beginning PEEP ventilation, initial values being regained after 120 min. During the period of apnoea the arterial partial pressure of carbon dioxide almost doubled, and, when the tidal volume remained unaltered, was still some 20-30% above initial values at the end of 2 h, despite the use of PEEP. Normal PaCO2 levels were achieved on increasing the tidal volume by a factor of 1.4. The larger tidal volume had no influence on either the degree of shunt or the PaO2. The effective compliance, which was considerably reduced after near drowning, increased again with the use of delayed PEEP ventilation. On beginning respiratory resuscitation there was an initial tachycardia and, despite a fall in stroke volume, an increase in mean arterial pressure and cardiac output because of the previous hypoxia. Only minimal cardiocirculatory changes, and no change in oxygen availability, occurred secondary to the use of PEEP.

Animals↗
PubMed1983

[Use of chromogenic substrate in cerebrospinal fluid diagnosis].

Amidolytic assays with chromogenic substrates exhibit great sensitivity, easy management, and good reproducibility. Consequently, they can be used with advantage in the analysis of cerebrospinal fluid (CSF). CSF levels of alpha 2-macroglobulin, alpha 1-antitrypsin, and plasminogen can thus be determined without a concentration step prior to analysis--lowered alpha 1-antitrypsin levels included. Serum/CSF concentration ratios obtained with these assays agree well with data calculated from immunochemical procedures. Moreover, there was a good correlation between amidolytic and immunochemical procedures. These reflections make it apparent that they can be adapted for routine evaluation of the above mentioned parameters.

Cerebrospinal Fluid Proteins↗
PubMed1983

Nonspecific induction of beta-lactamase in Enterobacter cloacae.

Since the introduction of the new beta-lactamase-stable beta-lactam compounds, inducible beta-lactamases have become increasingly important clinically [1]. It has recently been pointed out that most beta-lactam antibiotics appear to be affected by these derepressed enzymes either by hydrolysis or by the nonhydrolytic barrier mechanism [2]. Until now, it has generally been assumed that beta-lactamases are induced only by the beta-lactam compounds themselves. We investigated an E cloacae strain that exhibited high levels of resistance to most beta-lactam antibiotics. (MICs were greater than 32 micrograms/ml, except for N-formimidoyl thienamycin and the penem compound Sch 29482). Spontaneous production of beta-lactamase (after overnight culture in Isosensitest broth) was only marginal. However, the induction potency of Schaedler's broth even exceeded that of cefoxitin, which is known to be a good inducer [2]. We evaluated the induction potency of various cyclic compounds, such as amino acids, vitamins, purine derivatives, and steroid hormones. Only tryptophane, thiamine, folic acid, and hemine proved to be effacious inducers. Consequently, we explored the possibility that biological fluids also exhibit induction potency. The addition of inactivated serum (at a concentration of 25%) to the Isosensitest medium led to an enzyme induction comparable to that of cefoxitin. Similar results could be obtained with the addition of pleural fluid, CSF, or urine. These observations confirm the previous report that Morganella morganii strains produced considerable amounts of beta-lactamase even in a group of animals that did not receive treatment with beta-lactam compounds (granuloma pouch model) [3].(ABSTRACT TRUNCATED AT 250 WORDS)

Enterobacter↗