A backboard makes manual chest compressions more effective on bed mattresses

1. Introduction

Cardiopulmonary resuscitation (CPR) is the initiation of manual chest compressions (MCC) and defibrillation as soon as possible [1]. Effective MCC should be delivered by pushing hard and fast, allowing the chest wall to return after each push, and minimizing the time that MCC is interrupted. It is recommended that to maximize the effectiveness of MCC, the patient should be placed in the supine position on a stable, hard surface [1, 2]. When considering a stable, hard surface, it is ideal to lower the patient to the floor and perform MCC on the floor. However, lowering a patient to the floor requires manpower and is difficult in patients undergoing dialysis, in an intensive care unit, for example, where the vessels are routed and connected to medical pieces of equipment. In such cases, MCC is initiated in bed. To provide a stable, hard, flat surface on the bed, there are two options: on a hard medical mattress (hereafter referred to as the mattress) as it is, or with a backboard placed behind the patient’s back. It has been reported that MCC is more effective when performed with a backboard [3, 4]. It has also been reported that MCC on a bed is influenced by the firmness of the mattress [5, 6]. However, there are several different types of mattresses, such as pressure distribution, rehabilitation, pressure sore prevention and standard models, each with different firmness, material and thickness, so that the choice can be tailored to the patient’s condition. Medical industries have no standards for mattress firmness. These different types of mattresses have not yet been fully researched. Still, the use of backboards remains controversial even in the global guidelines. Only manikin-based studies are available thus human trials are still needed. However, if it is still ethically and technically difficult to start a new study, thus new results as well as past data are important. Because the mattresses on which patients lie have advanced with time, and the conditions of patients in cardiopulmonary arrest are different from those of the past. Therefore, this study tested the need for a backboard and its effects by evaluating the depth of MCC, MCC recoil, and success rates of MCC on five different mattresses of varying firmness, comparing groups where MCC was performed without a backboard, with a backboard, or when MCC was performed on the floor.

2. Materials and methods

3. Results

3.4 Participant’s fatigue (VAS scale)

The median VAS Scale with and without backboard insertion is shown in Table 2 and Fig. 1D. There were no significant differences in any of the median compared to the others.

Fig. 1.Measurement Results. (A) Depth of MCC (p < 0.01). (B) Recoil of MCC (p < 0.01). (C) MCC success rate (%) (p < 0.05). The brackets at the top of the figures for (A), (B) and (C) indicate significant differences at both ends. (D) MCC performing participant’s fatigue (VAS Scale). F: when the manikin was placed directly on the floor. VAS: visual analog scale.

4. Discussion

Traditionally, it has been recommended that CPR should be started as soon as possible with the patient lying supine on a stable, hard, flat surface [9, 10]. In addition, the use of backboards has been mentioned in major guidelines for CPR in bed. However, the 2020 guidelines still did not point to the use of backboards in the absence of clear evidence of their usefulness (Table 3). When MCC is needed, time is of the essence, and it is very difficult to get a patient from the bed to the floor, particularly if a patient is receiving dialysis treatment, or is in an intensive care unit where medical equipment and vascular routes are connected. It is therefore necessary to best prepare the patient on the assumption that CPR will be performed in bed. If CPR is to be performed in bed, the question is how to accomplish MCC most effectively. One strategy to increase the effectiveness of MCC in bed is the use of backboards. Recent studies indicate discrepancies in their results. For example, there are reports where MCC was performed using a 10 kg manikin on mattresses or air mattresses showing no significant differences in MCC parameters, with or without backboards for both mattresses and air mattresses. Another study suggested that MCC may not be performed at sufficient depth if the mattress is soft [11, 12]. Notably, it has been reported that backboards had no effect on MCC efficiency when the surface supporting the patient is minimally padded, as in cases when the patient is positioned on a stretcher with a 10 mm mat. Furthermore, there are reports of no significant differences due to the position of the practitioner, the height of the bed, the presence or absence of a backboard, or the posture of the patient [13]. Although some reports have denied the effectiveness of backboards, the usefulness of backboards cannot be determined without clear definition of the actual situation. For example, manikins are made of rigid materials, that are not directly comparable of the condition of a patient’s body either in bed or on the floor with respect to the efficiency of MCC results. Thus, it is important to be aware of what would happen to a real human body when evaluating results with manikins which can be a useful surrogate when a study is thoughtfully designed. Importantly, the psychological aspect of the practitioner must also be taken into account as the practitioner’s performance is the critical determinant for saving a person’s life when CPR is needed. In other words, if the mattress is soft, the practitioner may be inclined to push harder; if it is firm, the practitioner may be inclined to push in the same way as on the floor. In a report on the usefulness of MCCs with backboards inserted, it was the results indicated that the use of backboards deepened the depth of the manikin’s MCC by 5 mm [4, 14]. In addition, in terms of backboard width, a narrow backboard (600 mm × 500 mm) deepened the MCC by 1.9 mm, and a wide backboard (890 mm × 500 mm) deepened MCC by 2.6 mm [15]. In addition, this report found that the mattress sink rate was 4.7% less for the narrow backboard and 6.6% less for the wide backboard, compared to the condition without a backboard inserted [15]. Although the backboard used in the current study being presented was narrow (600 mm × 400 mm), the results showed that the depth and recoil of the MCC were significantly better with the backboard. Therefore, it was considered that a wider backboard would be more effective. In a previous validation of two types of backboards, one large and one small, in two directions (vertical and horizontal), it was reported that the larger backboard supported the back of the patient better and increased the efficiency of MCC [16]. In addition, the orientation in which the backboard was placed indicated that it supported the mattress better when it was inserted vertically [17]. Noordergraaf et al. [18] also reported that the softer the mattress and the deeper the MCC depth, the greater the effect of the backboard. This suggests that patients placed on softer mattresses could critically benefit from the insertion of a backboard, as the mattress is already sunk to some extent as seen by using heavy manikins in these studies, and that there is less scope for further sinking by the MCC procedure. Prior to the study presented here, the sinking of all mattresses of different thicknesses was measured by placing a 10 kg pillow weight on placed on the mattress (Table 1). Our results showed that the sinkage of the M3 and M5 type mattresses was greater than that of the other mattresses examined. Hypothesizing that MCC can be more effectively performed when using a backboard in cases where the sunken depth is large, the pressure applied during MCC may be reduced when backboards are used in children and light-weight patients, who are considered to have less sunken depth. Regardless of the firmness of each mattress type used in our study, the MCC was more efficient for all mattresses when backboards were used. Based on these results, we consider that the use of backboards has a positive effect. In a mattress-by-mattress comparison, no association was found between hardness, depth and recoil, despite all mattress hardness being different. M3 and M4 were standard thickness (100 mm) and soft. M3 was the softest and had the largest value sunk (−29.5 mm) in Table 1. Prior to the present study, it was assumed that mattress firmness might affect the mean depth of MCC. However, the actual results showed no obvious difference. This could be because the weight of the manikin itself already caused the mattress to sink, which affected the results, or because the manikin is made of a rigid material, which itself produces effective results for MCC on the bed. In addition, as the average depth was around 50 mm, it may be effective to perform MCC with an awareness of a target depth of 5 mm deeper in actual CPR. According to information published by the manufacturer, M1 is the hardest mattress and M3 is the softest. However, the mean values of the actual measured depths were different. This suggested that mattress firmness had little effect, but it cannot be ruled out that the order of mattresses in which MCC was performed and the fatigue level of the person performing the MCC had an effect. Furthermore, the patient’s weight on the mattress is an important factor to consider, especially for children and lighter patients, and the pressure applied during MCC should be adjusted accordingly. The mean values were higher when performed with a backboard inserted in case of all tested mattresses. Furthermore, the mean value of recoil was significantly higher when MCC was performed on the floor compared to the other cases. This confirms that the presence or absence of the use of a backboard is associated with recoil. It was inferred that the elasticity was improved by the insertion of the backboard.

The success rate of MCC may be influenced not simply by the firmness of the mattress, but also by the rigidity, back area, and weight of the manikin itself. By mattress type, it is inferred that mattress M1 was the standard 100 mm thick and the stiffest mattress, so no significant difference was found between the mattresses with or without a backboard; mattress M2 was slightly softer than M1, but 20 mm thinner, so no significant difference was found between the mattresses with and without a backboard; M3 and M4 are the same type of mattress, but with a standard thickness of 100 mm, and are even softer than M2, so we infer that there was a significant difference because the success rate would be lower if a backboard was not inserted. Regarding this finding, the backboard used in this study was 600 mm × 400 mm × 15 mm, so it cannot be ruled out that the effect may have been somewhat less than about the size of the upper body due to the backboard not being large enough, as reported by Cloete et al. [19]. Furthermore, M5 was the first mattress on which MCC was performed in the present study, and it is inferred that the difference between in MCC depth with and without backboard was not significant because the mattress tended to be pushed deeper without the backboard inserted. Fatigue experienced by the MCC practitioner was higher in the floor than when MCC was applied on the bed. This was thought to be because MCC on the bed was performed using the practitioner’s whole body, whereas MCC on the floor was performed mainly with the upper body on the knees. In this study, there were no significant differences in the participants’ fatigue levels “VAS” were found depending on the type of mattress or whether a backboard was inserted or not (Table 2). This suggests that posture and other factors influence fatigue of the person applying the MCC procedure. However, when MCC is performed on patients, the less manpower required for example to lift the patient out of bed or repositioning the patient and the sooner and the longer the MCC procedure can be applied, the better the outcome for the patient. Therefore, further detailed studies on factors that influence the fatigue experienced by the MCC performing practitioner are also needed in the future. Further studies to verify the effects of the mattress type, mattress firmness, and bed type as well as the size of the backboard with respect to a patient’s weight and size will help to optimize the outcome for patients requiring MCC. There is also concern that the human body is softer than a manikin, which would further reduce the efficiency of the MCC. Practitioners performed the MCC with at least 60 minutes of rest in between until the next trial, and the VAS was measured each time. Therefore, it is possible that fatigue increased during the sessions in this study, which may have affected the VAS. With the advancement and increase in medical equipment, the effectiveness of CPR varies between past and new products. However, the immediate application of CPR and the efficiency of MCC given to a patient in need, is still one of the most critical first responses to save a patient’s life. Thus, this research should continue with perseverance. The results from our study indicate that it is still too early and likely not warranted to conclude that backboards are unnecessary.

5. Conclusions

The results of this study indicate and therefore confirm that MCC can be performed more reliably with the insertion of a backboard, regardless of the firmness of a hospital bed mattress. Whenever possible, MCC should be performed with a backboard inserted if MCC is given to a patient in bed. In addition, when training MCC on the bed, consideration should be given to the firmness of the mattress and the weight of the manikin used.

Abbreviations

AHA, American Heart Association; CPR, Cardiopulmonary resuscitation; CoSTR, Consensus on Science with Treatment Recommendations; ERC, European Resuscitation Council; MCC, Manual chest compression; JRC, Japan Resuscitation Council; VAS, visual analog scale.

Availability of data and materials

The data presented in this study are available on reasonable request from the corresponding author.

Author contributions

AO, YK, TH and TY—designed the research study. AO, YK, MT, MK, KH and TS—performed the research. AO, YK, TT and TH—analyzed the data. AO and TH—wrote the manuscript. All authors read and approved the final manuscript.

Ethics approval and consent to participate

The Institutional Review Board at Jikei University of Health Care Sciences, Tokushima Bunri University and Kyushu university confirmed that no ethical approvals were required. Consent to participate in the study and written signatures were received.

Acknowledgment

We thank for helping with the study Takeshi Murakami, Department of Medical Technology, Kochi Medical School Hospital, Kochi, Japan, Tetsuya Yoshida, Foundation for Biomedical Research and Innovation at Kobe, Hyougo, Japan, Mika Yamada, Shikokku Central Hospital, Ehime, Japan, and Chikako Higashiyama, Department of Clinical Engineering, Kagawa University Hospital, Kagawa, Japan.

Funding

This research received no external funding.

Conflict of interest

The authors declare no conflict of interest.