The contribution of pH to exercise-induced arterial O2 desaturation was evaluated by intravenous infusion of sodium bicarbonate (Bic, 1 M; 200-350 ml) or an equal volume of saline (Sal; 1 M) at a constant infusion rate during a "2,000-m" maximal ergometer row in five male oarsmen. Blood-gas variables were corrected to the increase in blood temperature from 36.5 +/- 0.3 to 38.9 +/- 0.1 degrees C (P < 0.05; means +/- SE), which was established in a pilot study. During Sal exercise, pH decreased from 7.42 +/- 0.01 at rest to 7.07 +/- 0.02 but only to 7.34 +/- 0.02 (P < 0.05) during the Bic trial. Arterial PO2 was reduced from 103.1 +/- 0.7 to 88.2 +/- 1.3 Torr during exercise with Sal, and this reduction was not significantly affected by Bic. Arterial O2 saturation was 97.5 +/- 0.2% at rest and decreased to 89.0 +/- 0.7% during Sal exercise but only to 94.1 +/- 1% with Bic (P < 0.05). Arterial PCO2 was not significantly changed from resting values in the last minute of Sal exercise, but in the Bic trial it increased from 40.5 +/- 0.5 to 45.9 +/- 2.0 Torr (P < 0.05). Pulmonary ventilation was lowered during exercise with Bic (155 +/- 14 vs. 142 +/- 13 l/min; P < 0.05), but the exercise-induced increase in the difference between the end-tidal O2 pressure and arterial PO2 was similar in the two trials. Also, pulmonary O2 uptake and changes in muscle oxygenation as determined by near-infrared spectrophotometry during exercise were similar. The enlarged blood-buffering capacity after infusion of Bic attenuated acidosis and in turn arterial desaturation during maximal exercise.

The safe delivery of adequate analgesia and appropriate sedation is a priority in prehospital care. The use of ketamine is described for analgesia and sedation in 1030 trauma patients in a physician-led prehospital trauma service. Ketamine was mainly used in awake non-trapped patients with blunt trauma for procedural sedation and analgesia. Detailed database searches did not demonstrate loss of airway, oxygen desaturation or clinically significant emergence reactions after ketamine administration. Ketamine is relatively safe when used by physicians in prehospital trauma care.

The safe delivery of adequate analgesia and appropriate sedation is a priority in paediatric pre-hospital care. Ketamine was predominantly used in awake non-trapped patients with blunt trauma for procedural sedation and analgesia. Detailed database searches did not demonstrate loss of airway, oxygen desaturation or clinically significant emergence reactions after ketamine administration. This study failed to demonstrate any major side effects of the drug and reassured us that the safety profile of the drug in this environment is likely to be satisfactory. The use of ketamine in trapped children was rare.

IntroductionWe describe a system of scenario-based training using simple mannequins under realistic circumstances for the training of pre-hospital care providers.MethodsA simple intubatable mannequin or student volunteers are used together with a training version of the equipment used on a routine basis by the pre-hospital care team (doctor + paramedic).Training is conducted outdoors at the base location all year round. The scenarios are led by scenario facilitators who are predominantly senior physicians. Their role is to brief the training team and guide the scenario, results of patient assessment and the simulated responses to interventions and treatment. Pilots, fire-fighters and medical students are utilised in scenarios to enhance realism by taking up roles as bystanders, additional ambulance staff and police. These scenario participants are briefed and introduced to the scene in a realistic manner. After completion of the scenario, the training team would usually be invited to prepare and deliver a hospital handover as they would in a real mission. A formal structured debrief then takes place.ResultsThis training method technique has been used for the training of all London Helicopter Emergency Medical Service (London HEMS) doctors and paramedics over the last 24 months. Informal participant feedback suggests that this is a very useful teaching method, both for improving motor skills, critical decision-making, scene management and team interaction. Although formal assessment of this technique has not yet taken place we describe how this type of training is conducted in a busy operational pre-hospital trauma service.DiscussionThe teaching and maintenance of pre-hospital care skills is essential to an effective pre-hospital trauma care system. Simple mannequin based scenario training is feasible on a day-to-day basis and has the advantages of low cost, rapid set up and turn around. The scope of scenarios is limited only by the imagination of the trainers. Significant effort is made to put the participants into "the Zone" - the psychological mindset, where they believe they are in a realistic setting and treating a real patient, so that they gain the most from each teaching session. The method can be used for learning new skills, communication and leadership as well as maintaining existing skills.ConclusionThe method described is a low technology, low cost alternative to high technology simulation which may provide a useful adjunct to delivering effective training when properly prepared and delivered. We find this useful for both induction and regular training of pre-hospital trauma care providers.