Effectiveness of mask ventilation in a training mannikin. A comparison between the Oxylator EM100 and the bag-valve device
Introduction
In 70–80% of cases, ventricular fibrillation is the most frequent cause of sudden cardiac death [1]. It can only be reversed in the few minutes after circulatory arrest. Hypoxemia, hypercapnia and acidosis then lower the fibrillation threshold and increase defibrillation tolerance [2]. Basic measures for resuscitation are therefore aimed at emergency oxygenation and carbon dioxide elimination. They depend, in part, on the ventilatory volume. Respiration, however, can cause problems. As long as the patient is not intubated, the medical personnel generally use a face mask and bag. This ventilatory technique, however, is difficult to manage and frequently causes complications [3]. Large and/or rapidly administered volumes lead to high pressure peaks with gastric inflation and risk of regurgitation and aspiration. Moreover, the magnitude of respiratory volume is still unclear [2]. This uncertainty is reflected in different recommendations 1, 4. The American Heart Association (AHA) recommends an optimal ventilatory dose of 800–1200 ml of air [1]. This recommendation is difficult to achieve for many emergency medical technicians [5], nursing personnel [6], anaesthetists [7], and even physicians [8]with reasonable instructions and practical experience. The European Resuscitation Council (ERC) is of the opinion that 500–600 ml of ventilatory volume suffices [4]. According to the ERC, this guideline is easier to follow and definitely eliminates the risk of gastric inflation. Moreover, if air is supplemented with oxygen, sufficient oxygenation can be obtained. It is, however, questionable whether enough carbon dioxide can be exhaled. In any case, even in the presence of a minimal circulation, the occurrence of hypercapnia depends directly on ventilatory magnitude [9].
An optimal ventilation apparatus should therefore be one that can be easily handled and still attain a sufficiently high ventilatory volume without risking gastric inflation.
The Oxylator EM100 is supposed to fulfil these requirements. Since pertinent investigations have not yet been undertaken, however, our aim was to study in a training mannikin whether the Oxylator EM100 compared with the Ambu®-Bag in fact improves ventilation and reduces gastric inflation.
Section snippets
Participants, materials and methods
This is a randomized crossover study. The AHA recommends 10–12 respirations per minute [1]. In our experience, on the average a maximum of 5–6 proper respirations (≥800 ml) per minute is attained. We therefore assumed that the Oxylator EM100 would attain an improvement from 6 to 9 proper respirations per minute or 27 per 3 min, respectively. Taking into account an α-error of 0.05 and a power of 0.8, at least three subjects are needed to prove this effect [10].
Group comparison
The participants obtained with the Oxylator EM100 a mean ventilatory volume of 1.196 ml (95% confidence interval of 1161–1231 ml) compared with 556 ml (95% confidence interval 507–605 ml) for the bag-valve-mask ventilation. The number of subjects who obtained an average ventilatory volume of 800 ml or more increased from 15% (11/72) with the Ambu®-Bag to 98.6% (70/72) with the Oxylator EM100 (P<0.001). Altogether, 46% (33/72) in the mask-bag group and 49% (35/72) in the Oxylator EM100 group
Discussion
In contrast to bag-valve-mask ventilatory volume, with the use of the Oxylator EM100, nearly all our participants obtained the ventilatory volume as recommended by the AHA. Handling of the Oxylator EM100 was simple and directions for use minimal. Moreover, no abdominal insufflations were encountered. It is particularly noteworthy that for the Ambu®-Bag, even with the low tidal volumes of 400–600 ml, which according to Baskett et al. are perceived adequate for resuscitation [12], the mean values
Conclusion
In summary we came to the following conclusions:
- 1.
With the Oxylator EM100, ventilation of a training mannikin is effective, with minimal risk of gastric inflation, simply and quickly learned.
- 2.
In a mannikin with a lung compliance of 50–55 ml/cm H2O and an oesophageal opening pressure of 30 cm H2O, the Oxylator EM100 obtains markedly less abdominal insufflation and a higher respiratory volume than the Ambu®-Bag.
- 3.
The trial procedure simulated a favorable situation with a high threshold for abdominal
Acknowledgements
We wish to express our gratitude to Mr R. Schoch, A Bollinger AG, Ch-Fehraltorf representative in Switzerland of CPR Medical Devices, Inc., Canada, who made the Oxylator EM100 available to us and assisted us in its management. We also wish to thank all the participants for their cooperation in carrying out this study and the reviewers for their valuable suggestions.
References (15)
- Cummins RO. Textbook of Advanced Cardiac Life Support. Dallas, TX: AHA,...
- Idris AH, Florete Jr OG, Melker RJ, Chandra NC. Physiology of ventilation, oxygenation and carbon dioxide elimination...
- et al.
Pulmonary aspiration during unsuccessful cardiopulmonary resuscitation
Intensive Care Med
(1987) Guidelines for the basic management of the airway and ventilation during resuscitation
Resuscitation
(1996)- et al.
An evaluation of emergency medical technicians' ability to use manual ventilation devices
Ann Emerg Med
(1983) - et al.
Artificial ventilation for cardiopulmonary resuscitation
Med J Aust
(1984) - et al.
Ventilatory volumes using mouth-to-mouth, mouth-to-mask, and bag-valve techniques
Respir Care
(1986)
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