The Laerdal pocket mask: effects of increasing supplementary oxygen flow

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.

Comparison of mouth-to-mouth, mouth-to-mask and mouth-to-face-shield ventilation by lay persons

OBJECTIVE AND METHODS

A prospective randomised study on 70 volunteers without previous first aid education (42 males, 28 females, mean age 17) was performed to compare mouth-to-mouth ventilation (MMV, n = 24) versus mouth-to-pocket-mask ventilation (MPV, n = 25) and mouth-to-face-shield ventilation (MFV, n =21), and to evaluate if an instruction period of 10 min would be sufficient to teach lay persons artificial ventilation. Every volunteer performed three ventilation series using a bench model of an unprotected airway.

RESULTS

MMV and MPV show higher mean tidal volume (TV) than MFV (values of series 3: 976 +/- 454 and 868 +/- 459 versus 604 +/- 328 ml, P = 0.002 and P = 0.025, respectively). We found a higher inter-individual variation in TV than in previous studies (P = 0.031). The recommended TV of 700-1000 ml was reached in only 23%, most frequently with MPV (MMV 16.7%, MPV 32%, MFV 19%) but the difference was not significant (P = 0.391). However, we found a significantly higher percentage with a TV below 700 ml with MFV (MMV 33.3%, MPV 36%, MFV 66.7% P = 0.047) and a significantly higher percentage of TV exceeding 1000 ml with MMV (MMV 50%, MPV 32%, MFV 14.3%) (P = 0.039). "Stomach" inflation was highest with MMV (79.2%) followed by MPV (52%) and MFV (42.9%) (P = 0.034). We found further differences between the sexes; males produced a higher TV (P = 0.003) and a higher percentage of stomach inflation (P = 0.029).

CONCLUSION

MPV showed the best ventilation quality. It resulted in a more adequate TV than MMV and MFV and lower stomach inflation than MMV. Only a relatively low percentage of ventilations were within the recommended range for TV and this may be related to the short training duration. We found different performances between the sexes, a high inter-individual variation and mainly a low ventilation quality. Therefore, further studies have to focus more on teaching duration, sex differences and ventilation quality.

Simply add oxygen: why isn't oxygen administration taught in all resuscitation training?

Resuscitation training is all about procedures, yet the overwhelming need is to get sufficient oxygen to hypoxic and endangered tissues. Neither the Australian Resuscitation Council nor the American Heart Association make mention in any basic courses of the need to add oxygen as soon as possible. The Australian Resuscitation Council has a separate policy on oxygen, and the American Heart Association mentions the need, but not until page 2274 of the 1992 'Guidelines'. Major first aid training organisations do not mention the use of oxygen resuscitation in basic courses. There seems to be a belief in first aid training that oxygen administration is potentially dangerous and is an 'Advanced' skill. Oxygen should be used as soon as possible, in as near 100% as possible in all resuscitation situations, and for the early management of injury and illness. Its use will never disadvantage a patient under these circumstances. This skill should be added into all resuscitation training. In these days of high technology for all, we can easily add the simple skill of administration of oxygen, as soon as available, to basic life support and first aid. An oxygen supply should be as easily available as a fire extinguisher, and as simply used.

A new method of two-resuscitator CPR

Standard two-resuscitator cardiopulmonary resuscitation (CPR) (one resuscitator providing Bag Valve Mask (BVM) ventilation and one chest compressions) was compared with a modified method where one resuscitator held the mask while the second provided ventilation and compressions. Twenty-two subjects used both methods in random order on a recording manikin equipped to measure minute volume (Vm), tidal volume (Vt), respiratory rate (RR), compression rate (CR) and depth. Vm and Vt were greater with modified CPR, but the CR was slower. Percent of compressions < 38 mm, 38-51 mm or > 51 mm did not differ between techniques ((Modified--VM, 12.6 1 (S.D. 2.5); Vt, 1110 ml (S.D. 116); CR, 57 (S.D. 11), < 38 mm 6% (S.D. 14), 38-51 mm 36% (S.D. 33), > 51 mm 58% (S.D. 41); Standard--Vm, 9.7 1 (S.D. 3.8); Vt, 640 ml (S.D. 230); CR, 75 (10), < 38 mm 9% (S.D. 22), 38-51 mm 52% (S.D. 37), > 51 mm 38% (S.D. 38)). Modified CPR greatly improves ventilation but reduces CR.

A comparison of bag mask and mouth mask ventilation in anaesthetised patients

Anaesthetic residents used bag valve mask (BVM) or mouth mask (MM) ventilation, both with an O2 flow of 15 l min-1 to ventilate 30 ASA I or II anaesthetised patients for 4 min prior to endotracheal intubation. Mean nasopharyngeal O2 was higher with BVM (BVM 95% (S.D. 3%) MM 54% (S.D. 12%)). End tidal CO2 (ETCO2) was similar in both groups (ETCO2% at 4 min: BVM 4.65 (S.D. 0.84) MM 4.53 (S.D. 0.54)) but respiratory rate was faster with BVM (BVM 17 min-1 (S.D. 5) MM 12 min-1 (S.D. 4)). Peak (Paw) and mean (Paw) airway pressures were higher with MM and MM produced significant expiratory pressure [cmH2O: BVM Paw 16.7 (S.D. 5.3) Paw 4.2 (S.D. 2.1) MM: Paw 20.9 (S.D. 5.2) Paw 7.8 (S.D. 2.1)) minimum expiratory pressure: MM 2.4 (S.D. 1.1) BVM 0.2 (S.D. 0.4). Gastric insufflation was detected in two MM and two BVM patients. This tended to be more severe with MM ventilation. Although MM ventilation has some important disadvantages it can be used effectively by resuscitators with little or no experience in its use.