Basic Life Support Ventilation Research Articles

Basic Life Support Ventilation in Mountain Rescue

Cardiopulmonary resuscitation in the mountains usually has to be performed under difficult and hostile circumstances and sometimes for extended periods of time. Therefore, mountain rescuers should have the ability and the appropriate equipment to perform prolonged, efficient, and safe ventilation. Members of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) discussed the results of a literature review, focusing on the advantages and disadvantages of common ventilation techniques in basic life support and their training methods with specific respect to use in mountain rescue, and recommendations were proposed. Bystanders fear the potential risk of infection and lack the willingness to perform mouth-to-mouth ventilation, though the risk of infection is low. Mouth-to-mouth ventilation remains the standard technique for bystander ventilation and, in the absence of a barrier device, bystanders should not hesitate to ventilate a patient by this technique. For mountain rescue teams, we encourage the use of a barrier device for artificial ventilation. Mouth-to-mask ventilation devices are most likely to fulfill the requirements of being safe, simple, and efficient in the hands of a basic-trained rescuer. The use of a mouth-to-mask ventilation device is recommended for out-of-hospital ventilation in the mountains and should be part of the mountain rescuer's standard equipment. Bag-valve-mask ventilation is efficient, if performed by well-trained rescuers, but it leads to a low ventilation quality in the hands of a less experienced rescuer. It should be emphasized that regular training every 6 to 12 months is necessary to perform proper ventilation.

Effects of decreasing inspiratory flow rate during simulated basic life support ventilation of a cardiac arrest patient on lung and stomach tidal volumes

If the airway of a cardiac arrest patient is unprotected, basic life support with low rather than high inspiratory flow rates may reduce stomach inflation. Further, if the inspiratory flow rate is fixed such as with a resuscitator performance may improve; especially when used by less experienced rescuers. The purpose of the present study was to assess the effect of limited flow ventilation on respiratory variables, and lung and stomach volumes, when compared with a bag valve device. After institutional review board approval, and written informed consent was obtained, 20 critical care unit registered nurses volunteered to ventilate a bench model simulating a cardiac arrest patient with an unprotected airway consisting of a face mask, manikin head, training lung [with lung compliance, 50 ml/0.098 kPa (50 ml/cmH2O); airway resistance, 0.39 kPa/l/s (4 cmH2O/l/s)] oesophagus [lower oesophageal sphincter pressure, 0.49 kPa (5 cmH2O)] and simulated stomach. Each volunteer ventilated the model with a self-inflating bag (Ambu, Glostrup, Denmark; max. volume, 1500 ml), and a resuscitator providing limited fixed flow (Oxylator EM 100, CPR Medical devices Inc., Toronto, Canada) for 2 min; study endpoints were measured with 2 pneumotachometers. The self-inflating bag vs. resuscitator resulted in comparable mean±SD mask tidal volumes (945±104 vs. 921±250 ml), significantly (P<0.05) higher peak inspiratory flow rates (111±27 vs. 45±21 l/min), and peak inspiratory pressure (1.2±0.47 vs. 78±0.07 kPa), but significantly shorter inspiratory times (1.1±0.29 vs. 1.6±0.35 s). Lung tidal volumes were comparable (337±120 vs. 309±61 ml), but stomach tidal volumes were significantly (P<0.05) higher (200±95 vs. 140±51 ml) with the self-inflating bag. In conclusion, simulated ventilation of an unintubated cardiac arrest patient using a resuscitator resulted in decreased peak flow rates and therefore, in decreased peak airway pressures when compared with a self-inflating bag. Limited flow ventilation using the resuscitator decreased stomach inflation, although lung tidal volumes were comparable between groups.

Smaller tidal volumes with room-air are not sufficient to ensure adequate oxygenation during bag–valve–mask ventilation

The European Resuscitation Council has recommended decreasing tidal volume during basic life support ventilation from 800 to 1200 ml, as recommended by the American Heart Association, to 500 ml in order to minimise stomach inflation. However, if oxygen is not available at the scene of an emergency, and small tidal volumes are given during basic life support ventilation with a paediatric self-inflatable bag and room-air (21% oxygen), insufficient oxygenation and/or inadequate ventilation may result. When apnoea occurred after induction of anaesthesia, 40 patients were randomly allocated to room-air ventilation with either an adult (maximum volume, 1500 ml) or paediatric (maximum volume, 700 ml) self-inflatable bag for 5 min before intubation. When using an adult ( n=20) versus paediatric ( n=20) self-inflatable bag, mean ±SEM tidal volumes and tidal volumes per kilogram were significantly ( P<0.0001) larger (719±22 vs. 455±23 ml and 10.5±0.4 vs. 6.2±0.4 ml kg −1, respectively). Compared with an adult self-inflatable bag, bag–valve–mask ventilation with room-air using a paediatric self-inflatable bag resulted in significantly ( P<0.01) lower paO 2 values (73±4 vs. 87±4 mmHg), but comparable carbon dioxide elimination (40±2 vs. 37±1 mmHg; NS). In conclusion, our results indicate that smaller tidal volumes of ≈6 ml kg −1 (≈500 ml) given with a paediatric self-inflatable bag and room-air maintain adequate carbon dioxide elimination, but do not result in sufficient oxygenation during bag–valve–mask ventilation. Thus, if small (6 ml kg −1) tidal volumes are being used during bag–valve–mask ventilation, additional oxygen is necessary. Accordingly, when additional oxygen during bag–valve–mask ventilation is not available, only large tidal volumes of ≈11 ml kg −1 were able to maintain both sufficient oxygenation and carbon dioxide elimination.

Optimisation of tidal volumes given with self-inflatable bags without additional oxygen

The European Resuscitation Council has recommended smaller tidal volumes of 500 ml during basic life support ventilation in order to minimise gastric inflation. One method of delivering these tidal volumes may be to use paediatric instead of adult self-inflatable bags; however, we have demonstrated in other studies that only 350 ml may be delivered, using this technique. The reduced risk of gastric inflation was offset by oxygenation problems, rendering the strategy of attempting to deliver tidal volumes of 500 ml with a paediatric self-inflatable bag questionable, at least when using room-air. In this report, we assessed the effects of a self-inflatable bag with a size between the maximium size of a paediatric (700 ml) and an adult (1500 ml) self-inflatable bag on respiratory variables and blood gases during bag-valve-mask ventilation. After induction of anaesthesia, 50 patients were block-randomised into two groups of 25 each. They were ventilated with room-air with either an adult (maximum volume, 1500 ml) or a newly developed medium-size (maximum volume, 1100 ml; Dräger, Lübeck, Germany) self-inflatable bag for 5 min before intubation. When compared with the adult self-inflatable bag, the medium-size bag resulted in significantly lower exhaled tidal volumes and tidal volumes per kg bodyweight (624±24 versus 738±20 ml, and 8.5±0.3 versus 10.7±0.3 ml · kg −1, respectively; P<0.001), oxygen saturation (95±0.4 versus 96±0.3%; P<0.05), and partial pressure of oxygen (78±3 versus 87±3 mmHg; P<0.05). Carbon dioxide levels were comparable (37±1 versus 37±1 mmHg). Our results indicate that smaller tidal volumes of about 8 ml · kg −1 (approximately 600 ml), given with a new medium-size self-inflatable bag and room-air, maintained adequate carbon dioxide elimination and oxygenation during bag-valve-mask ventilation. Accordingly, the new medium-size self-inflatable bag may combine both adequate ventilatory support and reduced risk of gastric inflation during bag-valve-mask ventilation.

Effects of smaller tidal volumes during basic life support ventilation in patients with respiratory arrest: good ventilation, less risk?

Objective: When ventilating an unintubated patient in cardiac or respiratory arrest, smaller tidal volumes of 500 ml instead of 800–1200 ml may be beneficial to decrease peak airway pressure, and to minimise stomach inflation. The purpose was to determine the effects of small (∼500 ml) versus large (∼1000 ml) tidal volumes given with paediatric versus adult self-inflatable bags and ∼50% oxygen on respiratory parameters in patients during simulated basic life support ventilation. Methods: While undergoing induction of anaesthesia, patients were randomised to three minutes of ventilation with either an adult ( n=40) or paediatric ( n=40) self-inflatable bag. Results: When compared with an adult self-inflatable bag, the paediatric bag resulted in significantly lower mean (±standard deviation) exhaled tidal volume (365±55 versus 779±122 ml; P<0.0001), peak airway pressure (20±2 versus 25±5 cm H 2O; P<0.0001), but comparable oxygen saturation (97±1% versus 98±1%; NS (nonsignificant)). Stomach inflation occurred in five of 40 patients ventilated with an adult self-inflatable bag, but in no patients who were ventilated with a paediatric self-inflatable bag ( P=0.054). Conclusion: Administering smaller tidal volumes with a paediatric instead of an adult self-inflatable bag in unintubated adult patients with respiratory arrest maintains good oxygenation and carbon dioxide elimination while decreasing peak airway pressure, which makes stomach inflation less likely.