Premature failure of battery-powered syringe pumps

Failure of battery-powered equipment during the interhospital transfer of patients is potentially life threatening. The time to failure of 60 fully-charged identical syringe pumps (20 from each batch purchased in 1992, 1994 and 1995) was measured. Older pumps were associated with less predictable charge capacity, with 40% of the 1992 pumps failing within 60 min. The premature failure of these pumps is most likely due to poor battery care. It is unsafe to assume that a fully-charged, battery-powered pump will continue to function throughout a long transfer. The routine carriage of spare pumps or a backup power supply is recommended.     

Gastro-oesophageal reflux during day case gynaecological laparoscopy under positive pressure ventilation: laryngeal mask vs. tracheal intubation

This study aimed to evaluate whether or not the use of intermittent positive pressure ventilation via the laryngeal mask airway is associated with a higher risk of gastro-oesophageal reflux when compared with intermittent positive pressure ventilation via a tracheal tube in patients undergoing day case gynaecological laparoscopy in the head down position. Sixty healthy women were randomly allocated to receive either the laryngeal mask or cuffed tracheal tube for intra-operative airway maintenance. Using continuous oesophageal pH monitoring, four patients in the tracheal tube group and none in the laryngeal mask group had evidence of gastro-oesophageal reflux (as indicated by a decrease in oesophageal pH to below 4). The difference in the incidence of reflux did not achieve statistical significance (p = 0.11). In conclusion, we found no evidence to suggest that the use of intermittent positive pressure ventilation via the laryngeal mask increases the risk of gastro-oesophageal reflux in patients undergoing elective day case gynaecological laparoscopy.     

Bilateral lingual nerve injury following the use of the laryngeal mask airway

We report a 27-year-old patient who developed transient bilateral lingual nerve palsy following the use of a laryngeal mask to maintain the airway during a general anaesthetic for arthroscopy of the wrist.     

Das Vibrationsempfinden

Zusammenfassung Mit einem Vibrationsgerät (250 Hz; stufenförmige Einzelmessungen) und mit der Stimmgabel wurden die Schwellen des Vibrationsempfindens bestimmt. Wir untersuchten 100 gesunde Personen, 24 Patienten mit multipler Sklerose und 29 mit Polyneuropathie verschiedener Genese.Es ergab sich ein altersabhängiger Schwellenanstieg, der besonders deutlich um das 50. Lebensjahr herum ausgeprägt ist. Der günstigste Reizort an der unteren Extremität war die Großzehe (Kuppe oder Gelenk). Hier lagen die Schwellen deutlich niedriger, und die Streuungen waren geringer als am Malleolus medialis oder der medialen Tibiafläche. Die Fingerkuppe ist noch empfindlicher und zeigte auch einen viel geringeren altersabhängigen Schwellenanstieg.Es bestanden keine Geschlechtsunterschiede und keine Differenzen zwischen dominierender und nichtdominierender Körperhälfte. Im Vergleich ist die Stimmgabeluntersuchung weniger empfindlich, besonders im fortschreitenden Lebensalter. — Bei den untersuchten Patienten fanden sich in fast allen Fällen Erhöhungen der Vibrationsschwellen im Vergleich zur Streubreite der altersabhängigen Normalkurve.

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Vibratory sensibility

Summary The thresholds of vibratory sensation were determined by means of a vibratory device (250 cps; measurements in gradual increments) and a tuning fork. We examined 100 normal subjects, 24 patients with multiple sclerosis and 29 patients with polyneuropathy of variable origin.There is an elevation of threshold with age which is most marked at about 50 years of age. The body area at the lower extremities most suitable for testing was found to be the big toe (tip or joint). The thresholds near this point are significantly lower than those at the malleolus medialis or the inner aspect of the tibia, the deviation in results being also small. The tip of the index finger is even more sensitive, showing only a small rise in threshold with age.There were no differences either between male and female subjects or between the dominant and non-dominant body side. The determination of the threshold with a tuning fork appears to be less sensitive, especially in older individuals. The thresholds in the patient groups examined were almost consistently elevated as compared with those of normal subjects.

     

Dead space and paediatric anaesthetic equipment: a physical lung model study

Untested assumptions have been made with regard to functional dead space in facemasks, filters and breathing systems used in children for the administration of inhalation anaesthesia. Total functional dead space was measured in various combinations of this equipment applied to a spontaneous ventilation lung model with parameter settings appropriate for infants of 7-8 kg. We found that functional dead space was too large to allow for spontaneous ventilation of the lungs when a breathing filter was fitted. There was minimal relationship between size of the facemask and functional dead space; however, the provision of 22-mm female inlets to facemasks achieved proportionately less functional dead space than with 15-mm male inlets. Regardless of the apparatus used and the magnitude of the dead space, the leak induced when a poorly fitting facemask was used dramatically reduced the dead space of the breathing system - to near optimal conditions - by moving the alveolar gas elimination point to within the facemask itself.     

The air elimination capabilities of pressure infusion devices and fluid-warmers

Pressurised infusion devices may have only limited capability to detect and remove air during pressurised infusions. In order to assess pressure infusion systems with regard to their actual air elimination capabilities four disposable pressure infusion systems and fluid warmers were investigated: The Level 1 (L-1), Ranger (RA), Gymar (GY), and the Warmflo (WF). Different volumes of air were injected proximal to the heat exchanger and the remaining amount of air that was delivered at the end of the tubing was measured during pressurised infusions. Elimination of the injected air (100-200 ml) was superior by the RA system when compared to L-1 (p < 0.01). The GY and WF systems failed to eliminate the injected air. In conclusion, air elimination was best performed by the RA system. In terms of the risk of air embolism during pressurised infusions, improvements in air elimination of the investigated devices are still necessary.