Summary Peripherally inserted central catheters are increasingly used to provide access to the central venous circulation. They are commonly positioned ‘blind’ using a variety of anthropometric techniques and operator experience to direct insertion length. Malposition rates are poorly defined because of differing insertion techniques, difficulties defining anatomical tip position on chest radiographs, controversy over what constitutes an adequate catheter position and possible differences between patient groups. We have developed a reproducible method to define catheter positions on chest radiograph and have applied this in a retrospective analysis of 256 ICU and 243 non‐ICU catheter insertions over a 6‐month period. Two different definitions were used for adequate position. ‘Blind’ positioning of peripherally inserted central catheters was associated with a definition‐dependent malposition rate of 42–76%. Malposition rates were significantly higher in ICU patients. Emerging technologies may assist in reducing these high rates.
The analgesic effects of systemically administered diamorphine, caudal analgesia with 0.5% bupivacaine plain and caudal analgesia with 0.5% bupivacaine plain to which morphine sulphate had been added were studied in boys undergoing circumcision. Postoperative analgesia was assessed using a linear analogue scale. The time interval between operation and subsequent analgesic administration and the number of analgesic doses in 24 h were compared. The frequency of vomiting was noted. All three methods provided satisfactory results. The only detectable difference between the groups was a more rapid, but transient, recovery in the group receiving plain bupivacaine only. The frequency of vomiting was high in all groups. Caudal analgesia, with or without the addition of morphine, did not confer any advantage over injected diamorphine, and did not justify the extra time, risk and expense required to carry it out.
Lorazepam (Ativan, Wyeth) at dosages of 20-36 mg/kg was used to test for developmental toxicity in the mouse embryo/foetus model. Two separate regions were considered: (1) the central nervous system and (2) the roof of the mouth and the eyelids. In the first case a single administration of lorazepam was applied at the very beginning of the 9th gestation day. In the second, it was administered in preliminary tests on two consecutive gestation days between the 11th and 14th days and in later experiments once only on the 13th or 14th gestation day. In the first part of investigations regarding the development of the central nervous system, lorazepam unlike many other neurotropic drugs, was found not to induce any aberrations in the process of the neural tube closure. In the second part, in which palate closure and the temporary closure of eyelids were monitored, it was found that lorazepam does interfere with these processes. In order to test whether lorazepam's neurocristopathic activity can be prevented, suggesting the presence of benzodiazepine receptors in the neural crest cells, we used the benzodiazepine antagonist, flumazenil (Anexate, Roche). The results of these experiments indicated the flumazenil was able to prevent cleft palate and open eyelids cases almost completely if it was administered 3 hr after administration of lorazepam. If the treatments were administered in the reverse order, the frequency of neurocristopathy cases was unaffected, i.e. flumazenil did not influence the teratogenic activity of lorazepam.
Pressure-volume relationships for the total respiratory system and for the lung were recorded in anaesthetized and paralysed patients, during deflation from an airway pressure of 3 kPa to FRC at a rate of 2 litre min-1. Pleural pressure was estimated by means of an oesophageal balloon. A group of nine female patients (mean age 32.7 yr) about to undergo laparoscopy were each studied in four successive states: supine, 15 degrees head down tilt, tilt and lithotomy position, and again in this position after abdominal inflation with nitrous oxide to a pressure of 0.8(-1) kPa. Compliance values were calculated from the curves. Mean total compliance was increased significantly by moving to the lithotomy position, and reduced markedly after inflation of the abdomen, because of a large reduction in thoracic compliance. Mean lung compliance was unaltered, except for a slight but statistically significant increase on moving from the supine to the Trendelenburg position. Measurement of FRC by helium dilution in a group of seven patients showed that abdominal inflation caused a mean decrease of 19%. Airway closure manoeuvres were carried out using a helium bolus technique from FRC in five patients, but closing volume could be measured in only one patient, in the supine position. The absence of an inflexion in the slope of the pressure-volume curves for the other patients supported this negative finding.
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