Tissue elastance and fluid conduction in normotensive and hypertensive intracerebral mass haematomas

This is an investigation into the prognostic factors of 117 patients with spontaneous normo- and hypertensive intracerebral haematomas, supported by animal experiments. Preserved tissue elastance and fluid conduction enables the drainage of intrinsic haematoma serum into the CSF spaces in normotensive patients, who showed an increased extension of a perifocal hypodensity in the CT. Arterial hypertension decreased the possibility of fluid resolution. Our experimental studies showed that in hypertensive cases the serum remained trapped in the haematoma, which explains the small hypodense area around the haematoma in most of the hypertensive cases. If as an exception in hypertensives of perifocal hypodensity develops then it acts as additional space-occupying factor. Corresponding observations were made in hypertensive animals which showed a reduced serum movement out of the haematoma, but an increased Evans-Blue content in the perifocal tissue. Both pathological mechanisms explain the poorer prognosis in patients with intracerebral haematomas associated with high arterial blood pressure.

Pathomechanism of brain oedema in experimental intracerebral mass haemorrhage

The prognosis of intracerebral haemorrhage is extremely poor when arterial hypertension is present. We investigated elastance of the brain tissue and brain hydraulic conductivity in normotensive (MAP approximately 110 mmHg) and hypertensive (MAP approximately 170 mmHg/angiotensin infusion) cats following a stereotactically produced intracerebral haemorrhage. For 12 hours after the onset of haemorrhage we registered the course of ICP, subsequently the water content of cortex, white matter and basal ganglia as well as the interstitial concentration of serum proteins in the corresponding regions were determined (Evans-Blue, immunofluorescence). Hypertension was associated with a slight increase in ICP and tissue water content but with a 3 fold more elevated content of interstitial serum proteins. Immunofluorescence analysis showed the oedema in the hypertensive group to be vasogenic in nature and in the normotensive cats to originate from the haematoma itself. The generally poor outcome of intracerebral mass haemorrhage in hypertensive subjects could be ascribed to the nature of the concomitant brain oedema, as described in this study.

The ultra-thin bronchoscope in management of the difficult paediatric airway

The use of an ultra-thin flexible fiberoptic bronchoscope with a single lumen diameter of 2.7 mm at the distal tip to assist intubation of paediatric patients with a difficult airway is reported. Two patients (ages 30 months and 18 months) with mandibular hypoplasia and one patient (three months) with the Pierre-Robin syndrome are reported. In each case two fiberoptic bronchoscopes were used. The first allowed introduction of topical local anaesthetic while the second and smaller one was used for tube placement.

[Catheterization of the internal jugular vein using sonography]

Localisation of the internal jugular vein (IJV) by anatomical landmarks is common clinical practice. Specific complications associated with this technique are documented. Cannulation of the IJV is likely to be safer, when performed under direct vision, provided by a sonographic device. Following sonographic visualization, we have cannulated the IJV of 50 patients without complications. The tested device (Echokamera SSD-210 DX combined with the small-part-transducer UST-558-5, 5 MHz, 34 mm) proved useful in facilitating IJV cannulation.

[Comparative study of the effect of muscle relaxants on the intraocular pressure]

Control of intraocular pressure is a major concern in ophthalmic anesthesia, especially in the presence of glaucoma or penetrating eye injury. The use of succinylcholine under these conditions is controversial. This study was undertaken to assess the effects of the neuromuscular blocking agents succinylcholine, pancuronium, metocurine, vecuronium, and atracurium on the intraocular pressure of dogs. The study was performed on five "conditioned" mature male foxhounds. The dogs were intubated immediately after induction with thiopental 10 mg/kg and ventilated with an O2/N2O mixture (FIO2 = 0.33). The ventilation was controlled to maintain an endtidal CO2 concentration of 5 vol.%. and anesthesia maintained with a fentanyl infusion of 10 micrograms/kg per hour. Direct and continuous measurements were taken of blood pressure (MAP), central venous pressure (CVP), and intra-ocular pressure (IOP), the latter via a 22-gauge needle inserted into the anterior chamber of the eye. A force-displacement transducer was attached to the hindpaw to monitor muscle twitch following supramaximal stimulation of the anterior tibial nerve. These four measurements were displayed on a multi-channel polygraph (Figs. 1 and 2). Control values were obtained and then succinylcholine 1 mg/kg, pancuronium 0.1 mg/kg, metocurine 0.3 mg/kg, vecuronium 0.1 mg/kg, or atracurium 0.4 mg/kg were given in a randomized fashion and on different days. Measurements of heart rate (HR), MAP, CVP, and IOP were noted at 2, 5, 10, 20, and 30 min after giving the neuromuscular blocking agent. The results, as displayed on the polygraphy, indicate that the least effect on IOP and cardiovascular state followed neuromuscular blockade with vecuronium and atracurium.(ABSTRACT TRUNCATED AT 250 WORDS)

[Fiber optic orotracheal intubation]

Fiberoptic intubation is widely accepted in the management of a "difficult airway". In the majority of these cases the underlying anatomical findings require a nasal approach. We report a case of fiberoptic intubation where nasal passage was not possible. Orotracheal fiberoptic intubation was easily performed using a Williams oral airway and a Patil-Syracuse face mask. We recommend this technique for those cases where fiberoptic intubation is indicated but contraindications to the transnasal route apply and an "asleep-intubation" is desired.

[Preoperative increase in the plasma concentration of free fatty acids during minor elective interventions using a conventional anesthesia technic with enflurane]

Plasma concentrations of free fatty acids (FFApl) can be used as a parameter to measure stress. The present study aimed to evaluate the changes in the concentration of FFA during perioperative stress caused by minor elective surgery under a standard anaesthetic technique using enflurane. The premedication administered included heptabarbital on the preoperative night and morphine with promethazine prior to the transfer of the patient to the theatre. Blood samples for the analysis of FFA were obtained from 12 patients at the following times: 1 day preoperatively (control, c), prior to induction of anaesthesia (s1), following the administration of thiopentone (s2), following tracheal intubation (s3), 10 min after the commencement of enflurane administration (s4), following surgical incision (s5), intraoperatively (s6), following extubation (s7), 1 h after extubation (s8), and on the 1st postoperative day (s9). FFA were extracted from plasma with hexane and analysed in duplicate by a specific and sensitive gas-chromatographic assay with flame ionisation detection using pentadecanoic acid as the internal standard. All FFApl from the preoperative day (c) were within normal range. FFA concentrations at s1, s2, s3 and (to a lesser extent) at s4 were statistically significantly increased compared to control values. The maximum concentration of FFA in plasma occurred at s2. A decrease from this maximum was found in samples s4, s5 and s6 (the latter was the minimum intraoperative FFApl). The FFApl levels at s7, s8 and s9 were similar to control. A different response was found for each individual free fatty acid. The maximum increase ranged from 40% (stearic acid) to 300% (oleic acid).(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of rectal pH values on the absorption of methohexital]

The factors underlying the unpredictability of the pharmacokinetics of rectally administered methohexitone remain unclear. The "pH partition hypothesis" offers an explanation. We investigated six children with rectal pH values ranging from 7.5 to 9.8, who were given 25 mg/kg methohexitone 10% via the rectal route under general anaesthesia. Blood samples were taken at zero, 3, 5, 7, 10, 15, 20, 30, 40, 60, 90 and 120 min; rectal pH was measured at zero and 1 min. The methohexitone plasma levels reached a maximum (Cmax) of 2.63 micrograms/ml (median) after 17.5 min (median). The elimination half-life ranged from 37 to 218 min. No positive correlation between lower pH and better resorption (AUC and Cmax) was found. The resorption kinetics of rectally administered methohexitone cannot be explained by its electrochemical properties alone.

Evaluation of two oxygen analyzers by computerized data acquisition and processing

Monitoring of inspired oxygen concentration during anesthesia with nitrous oxide is becoming accepted as essential. This type of monitoring demands accurate monitors that respond rapidly. We evaluated two such devices for their response patterns to rapid changes in oxygen concentration, a galvanic or "fuel cell" unit and a polarographic device. Data were stored after analog-to-digital conversion. The response patterns to stepwise changes in nitrous oxide and oxygen mixtures were recorded at flow rates ranging from 2 to 10 L/min. Both units responded accurately to all changes in the absolute oxygen concentration; the polarographic unit was, on average, twice as fast. Responsiveness to nitrous oxide was low (less than 0.4% at 100% nitrous oxide), and the stability of the signals was good. The 90% response time (T90) was consistent for any stepwise increase or decrease in oxygen concentration between 0, 21, 33, 50, and 100%. After a step change from 0 to 100% oxygen at a gas flow rate of 10 L/min, the T90 was 5.8 seconds in the polarographic device and 11.4 seconds in the galvanic device (p less than 0.01). After a decrease from 100 to 0% oxygen, the T90 was 0.6 second longer in both monitors. Comparing flow rates of 2 L/min with 10 L/min, the T90 was delayed by 1.1 and 2.3 seconds for an increase, and by 1.4 and 2.9 seconds for a decrease in oxygen concentration. Experimental data suggest that both sensors respond adequately during routine clinical use. The faster response of the polarographic device is probably of limited clinical relevance, but it may aid in calibration.

Effect of vecuronium on intraocular pressure

Intraocular pressure decreased by 22.6% in association with neuromuscular blockade produced by vecuronium 0.1 mg kg-1. This appeared to be the result of an indirect action possibly via an effect on CVP. Vecuronium would be a suitable neuromuscular blocker for patients undergoing eye surgery in whom an increase in IOP would be undesirable.

[Comparative study of analgesia and plasma level following rectal, intramuscular and intravenous administration of ketamine]

Ketamine 25 mg/kg was administered to five foxhounds by the intravenous, intramuscular or rectal route. Plasma concentrations were measured by gas-chromatography and analgesia was tested by two techniques. Intravenous application gave reliable analgesia and well reproducible plasma levels in all subjects. Distribution and elimination half lives were found to be 6 min and 55 min, respectively. Intramuscular injection resulted in peak-plasma levels around the twentieth minute, elimination half life was fifty-two minutes, bioavailability 90%. Analgesia proved satisfactory in four out of the five subjects and lasted longer than after intravenous injection. The rectal route produced a wide range of peak-plasma levels, the average peak appearing after 40 min. We found an elimination halflife of 43 min and a bioavailability of 30%. Analgesia was poor in four out of the five subjects. The low plasma levels following rectal application are due to the poor bioavailability and this appears to be the reason for the unsatisfactory results with this route of administration. Bioavailability depends on the site of application (drainage mainly through the vena cava or portal vein) and the pH of the rectum.

Effects of general and local anesthesia on the pharmacokinetics of cefazolin in patients undergoing orthopedic surgery

The pharmacokinetics of cefazolin in patients undergoing orthopedic surgery with either general (enflurane) or local (lidocaine or marcaine) anesthesia were studied. No differences in either mean serum levels at 30, 60, or 120 min after the intravenous injection of cefazolin or serum half-lives were seen between the two groups of patients.

[Endotracheal tubes for CO2 laser surgery of the larynx]

The CO2-Laser finds application in Larynx-Surgery at an increasing rate. The greatest hazard still is an ignition of the endotracheal tube by a Laser beam. The different measures currently being taken in order to reduce that risk are discussed.

[A new tube for laser surgery of the larynx]

A special tube for laser-surgery of the larynx ("Surgitek-Laser-Tube") was exposed to a CO2-Laser beam (Cavitron AO 300). In the common clinical range of settings, the tube proved to be relatively Laser-resistant. Increasing exposure resulted in damage to the surface and cuff. Also the metal coating decreased the I.D. significantly, which resulted in an unfavourable ratio of inner to outer diameter.