The current study revealed that mere adjustments of the BLS and AED protocol originally designed for hearing people do not suffice for effective training of the deaf. Three crucial tasks of the BLS and AED protocol were modified during an ergonomical analysis: breathing check, alerting emergency services and using an AED. Similar limitations were pointed out in research by Unnikrishnan et al. [4].
In the present study, BLS and AED knowledge was tested before the course using a previously developed questionnaire for schoolchildren [13]. The results suggest that BLS knowledge by deaf is poor (an average score of 3.5/10) compared to hearing peers (7.8/10) [14] and schoolchildren (an average score of 6.0/10, data not published yet). The most incorrect answers were to the basic questions representing the core of BLS, supporting the observation of insufficient BLS and AED knowledge by deaf.
Our study showed that BLS and AED performance was also poor as scored and assessed with the modified Cardiff test and a manikin with feedback data. In our observation, merely half of the participants would use safe approach to the cardiac arrest victim, check responsiveness, and send a text message to the rescue service. Less than half of them would open the airway and check initial breathing or send someone for help or an AED. Regarding chest compressions, more than 80 % of participants would perform chest compressions on the correct position with nearly 53 % of them compressing one third of the diameter of the chest, but less than half of them with an adequate rate. Better results were observed by Tomasetti et al. [15] where the deaf participated in the standard American National Red Cross 4-hour course using a videocassette signed by the course instructor and achieved 40/46 points on immediate post-test score. The best performance scores yielded on the manikin in the present study were compression score and flow fraction representing “low-flow” state in cardiac arrest. Overall performance score on the manikin was reduced on account of poorer results in ventilation score. There were some score discrepancies in BLS performance between modified Cardiff test and feedback data from the manikin. According to the manikin data, only 23 % of participants compressed the chest with the correct average depth of 50 to 60 mm compared to 52,9 % according to the modified Cardiff test. This fact could be due to more accurate and sophisticated measurements made by the manikin software, whereas the depth of the compression on the modified Cardiff test was estimated by observation.
Using the AED can be a challenge for a deaf person, as many AEDs provide only voice prompts [16]. On the other hand, the untrained deaf rescuers are capable of using AED appropriately with visual prompts after basic training [6]. Only four participants in our study failed to attach the AED pads in correct position and eight of them forgot to turn on the AED. Nearly 80 % of deaf rescuers put the AED into the visual field to be guided with visual instructions from the AED. They perform less successfully on the safety check and pressing the shock button. Also, Sandroni et al. described that 22 % of participants did not deliver shock. The reason was because they expected the defibrillator to do it automatically [6].
Communication is the basic challenge for educators of deaf people. The major differences between BLS instructions for deaf and non-deaf are the need for a sign interpreter, the need to modify the terminology of BLS instructions and the careful explanation of terminology [17]. During the pre-test we observed an extensive effort from the sign language interpreter to explain the meaning and the purpose of the questions. This observation together with the low score on pre-test could be due to low level of reading comprehension by deaf. It was shown that an average student with hearing loss graduates from high school with reading comprehension skills at about fourth grade level [8].
In addition, there is growing evidence in the literature regarding health literacy weaknesses by deaf [9, 10]. Findings from several studies indicate that deaf individuals have weaker functional health literacy and smaller found of cardiovascular health knowledge [9-11]. Nearly 40 % of deaf could not list any of the most common symptoms of a heart attack, while over 60 % of them could not list a single stroke symptom [9, 12]. Moreover, more than one third of deaf people would not call the emergency medical number if they thought they were having a heart attack or stroke, thinking that it is not deaf-accessible [9]. This observation is similar to our study where half of the participants wouldn’t send a message to the rescue service in the case of cardiac arrest although it could be activated through a text message. Although neither reading comprehension nor health literacy were analyzed in the present study, we assume that low level of both in our study group could contribute to the low scores on the pre-test.
Family conversations about family medical history and other incidental source of health knowledge are crucial for developing strong health literacy skills [11, 12]. In the present study the family member working as a healthcare provider is related to better results after the course. It is likely that a healthcare worker stimulates the conversation with other family members about the medical issues and through family communication promotes healthy life style including attaining BLS skills.
Deficits in reading comprehension and low level of health literacy have an impact on the BLS course. Presentation designed for deaf adults should use simpler English grammar and vocabulary, and more visual information [11]. Our BLS course was led by a physician accompanied with a sign language interpreter from non-medical field. It was shown that a signed interpretation appears to have been a better means of communicating BLS information to the deaf learners. The signed interpretation may eliminate poor reading comprehension as a potential barrier in learning and retention of BLS skills [15]. Changing position of the instructor during the presentation distract the deaf participants. This fact is due to the enhanced peripheral visual attention [18, 19] resulting in that the deaf subjects are more susceptible to peripheral distracters [20]. We also observed that attention duration by deaf people during the course was shorter than expected (it lasted between 25-30 minutes). This observation is supported by studies reporting that poor sustained attention in deaf children improved little with increasing years [21, 22].
The study has several limitations. Firstly, our method of obtaining participants through invitation send to the members of deaf associations resulted in a very small sample size. Secondly, the pre-test was designed for schoolchildren and not for deaf individuals. Due to reading comprehension and health literacy issues a specific pre-test should be developed for deaf adults. Thirdly, we used different measuring instruments before and after the course which made comparison of the results before and after an intervention inconvenient. Finally, we have not tested the retention of BLS and AED skills.