Anaesthesia
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We have developed an anaesthesia alarm system that responds in a more clinically appropriate manner than current threshold alarms. A decrease in systolic arterial pressure of 10 mmHg from a previous value of 70 mmHg has a greater clinical significance than a decrease of 10 mmHg from 150 mmHg. However, it has been difficult to envisage a simple algorithm for the detection of these contextually adverse changes in physiological variables. ⋯ This technique was developed further using Principal Component Analysis to isolate uncommon deviations from normal, clinically unimportant physiological variations. These clinically unimportant changes occur in a predictable fashion only if the sampling interval is 90 s or less. This new alarm system is asymmetric - a small decrease in systolic arterial pressure from 90 mmHg may, appropriately, set off an alarm but it would require a much larger increase in systolic arterial pressure to do so.
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Comparative Study Controlled Clinical Trial
Airway topicalisation in morbidly obese patients using atomised lidocaine: 2% compared with 4%.
We evaluated the technique of airway anaesthesia using atomised lidocaine for awake oral fibreoptic intubation in morbidly obese patients using two doses of local anaesthetic. Morbidly obese patients were allocated to receive either 2% or 4% lidocaine (40 ml) for oral airway anaesthesia using an atomiser with high oxygen flow. Patients were carefully sedated using midazolam and fentanyl. ⋯ Peak plasma lidocaine concentration was significantly lower in the 2% group (2.8 (0.8) microg.ml(-1) compared with 6.5 (1.0) microg.ml(-1), p < 0.05). Airway anaesthesia using atomised lidocaine for awake fibreoptic intubation in the morbidly obese is efficacious, rapid, and safe. Compared with 4% lidocaine, the 2% dose provides acceptable intubating conditions in most cases and produces lower plasma lidocaine levels.
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Electromagnetic interference is an important cause of pacemaker malfunction. We describe a case in which the use of a peripheral nerve stimulator at a pulse duration of 1 ms and a current of 1.4 mA led to complete but transient inhibition of a permanent pacemaker in a 73-year-old female who had undergone a total shoulder replacement.