Abstract
This study aimed to investigate the characteristics of chest compressions performed in dental chairs (DCs) with 2 different structural support designs and on the floor. This randomized prospective study was conducted to compare the effectiveness of chest compressions (rate and depth) using a feedback device and a manikin reporting system. The mean anterior chest wall motion measurements captured using the feedback device were significantly increased in the DCs than on the floor, whereas the percentage of net chest compression depths ≥5 cm as measured using the manikin reporting system were significantly decreased in the DCs than on the floor. These findings suggest that cardiopulmonary resuscitation performed in a DC without the use of a supporting stool or stiff backboard is not likely to be effective even if a DC design that incorporates a supportive steel column is utilized.
Keywords: Cardiopulmonary resuscitation, Chest compression, Dental chair
Cardiac arrest is a rare complication that can occur during dental treatment.1 In such a situation, dental providers ideally should initiate cardiopulmonary resuscitation (CPR) immediately while the patient is still positioned in the dental chair (DC).2,3 However, numerous reports have shown negative results regarding the efficacy of chest compressions performed on a patient in a DC primarily related to a lack of DC rigidity and/or stability. For example, the DC foundation may not be solid enough to support the patient during chest compressions due to a lack of steady vertical support between the DC backrest and the floor.4,5 If effective chest compressions cannot be safely performed due to the inherent design constraints of the DC, the patient should be carefully moved to the floor. However, moving an adult patient from the DC to the floor may not be safely and easily accomplished, which could result in delayed CPR initiation.
Fujino et al8 recommended use of a stool to help with stabilization during chest compressions performed while using a DC with insufficient foundational support. Therefore, if effective chest compressions are possible on a patient in a DC, this would enable immediate CPR initiation without needing to move the patient. With respect to the feasibility of chest compressions, numerous reports have highlighted a potential issue related to insufficient DC rigidity during chest compressions. This may be explained by the lack of a reinforced connection between the seat and the backrest, which permits flexing of the joint and downward vertical movement of the backrest. For this reason, a typical DC may not provide enough stability for effective chest compressions. Although a stool has been recommended to help with stability, it may be difficult to adequately position it under the DC backrest because of the DC design, which could result in delayed CPR initiation.
Although DC manufacturing companies have static load specifications detailing the maximum allowable patient body weight, there are no such specifications regarding dynamic loads like the additional forces present during chest compressions. In addition, DC design structure varies widely among manufacturers. Some DC designs incorporate a steel reinforcing center support, which may increase rigidity and positively impact the efficacy of CPR. These types of design factors may have affected the results of previous studies that assessed chest compressions performed on patients in a DC.
In the present study, we investigated the efficacy of chest compressions delivered to a patient in a DC without the use of a stabilizing stool by comparing the characteristics of chest compressions performed on the floor with those performed in 2 commercially available DCs with different back support and seat joint designs: with and without an additional steel supporting column.
METHODS
Forty-four sixth-year dentistry students participated in this prospective randomized controlled study. All participants received the same CPR training in accordance with the educational program of the dental school. The research purpose and methods were explained before the study. All procedures were conducted according to the Declaration of Helsinki. Approval of the Hiroshima University's Ethics Committee was obtained before this study was performed (E-548).
For this study, a CPR feedback device (CPR Meter, Laerdal Medical, Stavanger, Norway) was used along with a CPR training manakin (Heart Sim 4000, Laerdal Medical) to collect chest compression data. The CPR feedback device (CPR Meter) provided data on the motion of the anterior chest wall and the rate of chest compressions. The manikin-reporting system (Heart Sim 4000) provided data on the net chest compression depth. Study participants did not receive any information from the feedback device during chest compressions. A comparative analysis was conducted with the data obtained from the feedback device and the manikin-reporting system using data analysis software (ALS Skillmeter, Laerdal Medical).
The DCs were positioned so that the height of the manikin's anterior chest wall was 80 cm above the floor. The participants performed chest compressions while the feedback device was secured with double-sided tape to the center of the manikin's chest. All study participants performed CPR initially for 1 minute, followed by a 2-hour rest period, then another 1-minute round of CPR. The participants were randomly allocated to the following 3 groups: (a) group A performed continuous chest compressions on the manikin in DC-A (EOM-β, GC Corporation, Tokyo, Japan) and then DC-B (Spaceline EMCIA, Morita Manufacturing Corporation, Kyoto, Japan); (b) group B had the manikin positioned in DC-B first and then in DC-A; and (c) group C performed chest compressions with the patient positioned on the floor for both rounds of CPR.
Demographic variables were analyzed for each group, and chest compression data were analyzed using an analysis of variance (ANOVA) and Tukey HSD. The values are presented as the mean ± standard deviation. The analyses were performed using SPSS for Mac (version 25.0; SPSS, Inc, Chicago, IL). The results were considered statistically significant when the p value was <.05.
RESULTS
There were no significant differences for any of the demographic variables (gender, age, height, and body weight) between the 3 groups (Table). The average rates of chest compressions as measured with the feedback device were 103 ± 8/min (DC-A), 105 ± 13/min (DC-B), and 102 ± 8/min (floor), which were not found to be significantly different.
Table.
No Significant Differences Between the 3 Groups Due to Demographic Variables*
|
Demographics |
A (n = 14) |
B (n = 15) |
C (n = 15) |
P Value |
| Age, y | 24 ± 1 | 24 ± 2 | 24 ± 1 | .26 |
| Sex, male/female | 8/6 | 7/8 | 8/7 | .85 |
| Height, cm | 168 ± 10 | 163 ± 5 | 166 ± 10 | .88 |
| Weight, kg | 61 ± 9 | 56 ± 10 | 57 ± 11 | .47 |
All data are presented as means ± standard deviations.
The results from measuring the anterior chest wall motion using the feedback device are presented in Figure 1A. The chest wall motion associated with chest compressions delivered on the manikin positioned in DC-A, DC-B, and on the floor were 57 ± 9, 53 ± 8, and 48 ± 9 mm, respectively (p < .001, ANOVA). The anterior chest wall motion measurements during chest compressions with the manikin in DC-A were significantly deeper than those found with DC-B (p = .03, paired t test); however, the difference in chest wall motion measurements with the manikin in DC-B compared with being positioned on the floor was not significant (p = .32, unpaired t test).
Figure 1.
(A) Mean anterior chest wall motion measurements using the feedback device.
*p < .001 (analysis of variance [ANOVA]). (B) The percentage of compressions ≥5 cm using the manikin-reporting system. *p < .001 (ANOVA).
The percentage of net chest compression depths ≥ 5 cm for each group as measured by the manikin-reporting system are presented in Figure 1B. The percentages were 1 ± 8% (DC-A), 8 ± 22% (DC-B), and 32 ± 38% (floor). The percentage of chest compressions ≥ 5 cm was significantly lower when the manikin was in both DCs as compared with positioned on the floor (p < .001, ANOVA).
DISCUSSION
According to the 2015 American Heart Association guidelines, CPR should be initiated as promptly as possible for patients in cardiac arrest.5 If cardiac arrest occurs during dental treatment, chest compressions should be performed ideally with the patient remaining in the DC so that CPR can be immediately initiated.1 However, conflicting results have been reported on the effectiveness of CPR performed on patients in a DC.3 Fujino et al4,8 recommended the use of a strengthening prop (eg, a chair or stool) when performing chest compressions on a patient in a DC with insufficient rigidity and emphasized that placement of a stool under the DC backrest is needed for additional stability to improve CPR effectiveness. In addition, similar to the present study, Segal et al7 evaluated the feasibility of chest compressions in a DC using a feedback device and reported that the insufficient rigidity of a DC during compressions coupled with the tendency of the patient to sink into the DC padding may lead the rescuer to erroneously overestimate compression depth.5
In the current study, the impact of DC rigidity on the efficacy of chest compressions was assessed using 2 different chair designs as compared with the floor. The manufacturers of both DCs used in this study had set rigidity specifications in accordance with the Japanese National Specifications; therefore, the DCs were designed to have sufficient rigidity and motor torque to ensure that they could be raised when loaded with a patient weighing up to 130 kg (287 lb). However, no specifications for dynamic loads, such as those associated with chest compressions, are provided. The backrests of both DCs used in this study were made of inelastic hard plastics, and our results showed that the joint structures negatively impacted the effectiveness of chest compressions. In the DC-A design, the connection between the seat and the backrest consisted of 2 separate articulating joints, whereas in the DC-B design, the similar joint design also had the noted addition of a steel supporting column that could improve rigidity, provide more support for the backrest, and reduce sinking or vertical displacement during compressions (Figure 2). This difference in DC structure (ie, the reinforcing support) was considered to potentially have a major beneficial effect on backrest stability when subjected to dynamic loads. Our results demonstrated increased anterior chest wall motion during compressions performed in both DCs as compared with those delivered on the floor. However, the percentage of compressions reaching the 5- to 6-cm recommended depth range was significantly lower, approximating 1% (DC-A) and 8% (DC-B) versus 33% (floor), respectively. The mean vertical displacement of the anterior chest wall in DC-A was significantly larger than in DC-B indicating some benefit from the added steel support; however, the reinforcing column was not sufficient enough to facilitate consistent compression depths for effective CPR.
Figure 2.
Structure of the connecting joints between the seat and backrest of the dental chairs. Red arrows: Two lateral articulating joints in the DC-A and DC-B designs. Green arrow: Single steel supporting column in DC-B design. DC-A: EOM-β (GC Corporation). DC-B: Spaceline EMCIA (Morita Manufacturing Corporation). Abbreviations: DC-A, dental chair A; DC-B, dental chair B; EOM.
The design and spatial layout of many dental clinics is not overly conducive to moving large adult patients from the DC to the floor. The dental team should be aware of these potential limitations as well as what is needed to provide quality CPR until emergency medical services arrive. In situations where patients must remain in the DC while CPR is administered, the use of a firm backboard or back support should optimally be placed to counteract the patient sinking into the chair padding during compressions. As mentioned previously, some DCs may require a stool or prop to be placed under the chair back to counteract the tendency of the chair moving or rocking during CPR, especially considering that most DCs do not have reinforced joints between the chairback and the seat as found in DC-B. Therefore, consideration should be given to using a firm backboard in conjunction with a supporting stool or prop should a patient require CPR while in the DC.
This study has several limitations. First, all study participants did not rotate through the 3 groups. The floor participants did not perform chest compressions on the manikin while in the DCs, which may have introduced bias, potentially impacting the reliability and accuracy of the data. Furthermore, the chest compressions performed on the floor had an average depth of <5 cm, suggesting the participants may have lacked the proper skills to deliver adequate compressions. However, the chest compression rate was appropriate for all 3 study groups. The participants were relatively petite in size as compared with the manakins, which may have also affected the chest compression depth. Second, the weight of the manikin used in this study differed from that of adult patients. The manikin, which weighed 20 kg, was substantially less than the weight of an average adult patient, which may have impacted the stability of the DCs. Third, the height from the floor to the level of the manikin's anterior chest wall was fixed at 80 cm due to design and structural limitations of the DCs. Hong et al9 reported that a standing rescuer providing chest compressions on a patient positioned at a height of 80 cm or above will tend to deliver shallow compressions. As our participants had to perform compressions while standing, this may have affected the results of compression depth. Ideally, a step stool is recommended for clinicians to use during the compressions. Finally, the noted increase in vertical displacement could have been attributed to the patient sinking into the chair padding, which supports the recommendation for using a rigid backboard placed under the patient during CPR. However, the depth to which the manikin sank into the backrest padding at the time of chest compression was not measured, nor could we clearly identify which had a larger effect on the net compression depth, the joint structure or chair padding.
CONCLUSION
Our results demonstrated that chest compressions delivered with the patient positioned on the floor were significantly and consistently deeper than those in the DCs. Additionally, despite the increased vertical displacement of the anterior chest wall, the net compression depth decreased beyond the recommended range likely due to the combined effects of the patient sinking into the DC padding, insufficient rigidity of the DC joints, and inadequate DC foundational stability during chest compressions. Thus, to promptly respond to cardiac arrests during dental treatment, it is important to utilize a DC with a sufficiently rigid structure, such as a steel supporting column between the seat and backrest, as well as a supporting stool to minimize rocking and a firm backboard to prevent the patient from sinking into the padding during chest compressions.
ACKNOWLEDGMENT
The authors sincerely thank the students at Hiroshima University who participated in the study.
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