a b s t r a c t

Aim: The aim of the study was to assess whether Spinal immobilization with long back board (LBB) and semi-rigid cervical collar (CC) at 20? instead of 0? conserves pulmonary functions in obese volunteers, including Forced expiratory volume in 1 s (FEV1), Forced vital capacity , and FEV1/FVC ratio.

Methods: The study included adult volunteer subjects with android-type obesity who were otherwise healthy. First, pulmonary functions were tested in a seated position to obtain baseline levels, than volun- teers were immobilized with LBB and CC at 0-degree and measurements repeated at 0th and 30th minute of immobilization. Next day, same procedures were repeated with the trauma board at 20-degree. Changes over time in FEV1, FVC values and FEV1/FVC ratios during spinal immobilization at 0? and 20? were compared to baseline levels.

Results: Study included 30 volunteers. Results showed a significant decline in all values for both situa- tions following spinal immobilization (p < .001). We also compared the decrease over time in those val- ues (DFEV1, DFVC, and DFEV1/FVC ratio) during spinal immobilization at 0? and 20?. The decrease in pulmonary functions was similar in both groups (p > .05).

Conclusion: The present findings confirm that spinal immobilization reduces pulmonary functions in obese volunteers, and that 20-degree immobilization has no conservative effect on these values when compared to the traditional 0-degree immobilization. It may be that 20? is insufficient to decrease the negative effect of abdominal obesity on pulmonary functions.

(C) 2019

Introduction

Mortality and morbidity rates are high among multi-trauma patients, and several international guidelines routinely recom- mend spinal immobilization with long backboard (LBB) and semi-Rigid cervical collar (CC) for such patients [1,2]. However, the existing spinal immobilization literature reports little support- ing evidence for this approach [3-5], and previous studies have reported side effects of spinal immobilization that include pain, changes in vital signs, reduced pulmonary functions, skin ulcers, and increased intracranial pressure [6-11]. To address these side effects, some studies (including our own two recent studies) have evaluated the effect of spinal immobilization performed at 20? instead of the traditional 0? [12-14].

* Corresponding author.

E-mail address: [email protected] (G.C. Is ik).

A recent study investigating the conservative effect of 20- degree spinal immobilization on pulmonary functions in healthy subjects, the results showed an improvement [12]. However, one of the exclusion criteria was obesity. Given the increased incidence of obesity, and therefore of obese trauma patients–some of whom will already exhibit impaired Respiratory functions as a result of obesity itself–any conservative effect of 20-degree immobilization on pulmonary dynamics would be all the more vital [15]. For that reason, it seemed important to investigate whether this conserva- tive effect is more significant in the obese population than in the healthy non-obese population.

The aim of the study was to assess whether spinal immobiliza- tion with LBB and semi-rigid CC at 20? instead of 0? conserves pul- monary functions in obese volunteers, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio.

https://doi.org/10.1016/j.ajem.2019.04.022

0735-6757/(C) 2019

Materials and method

Study design

After receiving approval from the ethics committee, this prospective study was conducted with 30 obese volunteers between 01.11.2018 and 20.02.2019 at the emergency department of an academic teaching hospital. Written informed consent was obtained from all subjects prior to spinal immobilization, and pul- monary function measurements were performed.

Volunteer subjects

The study subjects were 30 adult volunteers of both genders with android-type obesity who were otherwise healthy, ranging in age between 18 and 45 years. Inclusion criteria were body mass index (BMI) of 30-40 kg/m² and waist-hip ratio (WHR) above 0.90 for males and above 0.85 for females, based on the World Health Organization (WHO) criteria for abdominal obesity [16]. Partici- pants were instructed to wear light clothes during measurement. Height was measured using a wall-mounted stadiometer, and weight was measured by an electronic scale. Waist and hip mea- surements followed the WHO STEPwise Approach to Surveillance (STEPS) protocol [16], requiring participants to stand erect with abdomen relaxed, arms at their side, and feet together while being measured. Waist circumference was measured with a tape at the approximate midpoint between the lower margin of the last palpa- ble rib and the top of the Iliac crest, at the endpoint of a normal expiration. Hip circumference was measured at the widest part of the buttocks.

Additional inclusion criteria were age over 18 and under 45 years, no acute or chronic diseases other than obesity, and nor- mal vital signs and physical characteristics at the time of the study. The exclusion criteria were pregnancy, failure to perform respira- tory function tests, any medical condition that would prevent the use of LBB and CC, and Abnormal vital signs or physical examina- tion findings at the time of the study.

Study protocol

All volunteers were asked to sleep for at least 8 h on the night before the study and to fast for at least 2 h prior to measurement of their pulmonary functions. All measurements were taken between 10 and 11 am. First, after a 30-minute rest period, volun- teers’ pulmonary functions were tested in a seated position to obtain baseline levels. The participant was then immobilized with LBB and CC at 0?, and measurements were repeated at 0 and 30 min of immobilization in that position. Pulmonary measure- ments were performed by a pulmonary physiotherapist, using the ZAN100 USB Spirometry system (Zan Messgerate). Respiratory function tests, which included FEV1 and FVC levels and FEV1/FVC ratio, followed the recommendations of the American Thoracic Society [17]. The process ended after these measurements were taken. On the following day, the same procedures were repeated with the trauma board at 20? for the same volunteers. All results were recorded on the study form (Fig. 1).

Sample size

The preferred sample size was determined using G-Power for Mac OS X (version 3.1.9.2; Universitat Dusseldorf, Germany). Our goal was to achieve sufficient statistical power to detect a 0.20 point decrease in FEV1 (DFEV1) for 0-degree and 20-degree immo- bilization over time. In line with previous studies, 0.27 points was considered an acceptable standard deviation [7,12]. Assuming a

two-sided a = 0.05, we anticipated a sample size of 25 patients for each group (0-degree and 20-degree) to achieve 80% power. An additional 5 patients were included in each group to account for potential protocol violations.

Statistical analysis

The statistical analysis was performed using the Statistical Package for the Social Sciences version 22.0 (SPSS Inc., Chicago, IL, USA). After assessing normal distribution using the Kolmogorov-Smirnov test, all variables were described in terms of mean +- standard deviation or median and interquartile range (IQR) (25-%75). The Friedman test was used to assess whether there was any significant change in pulmonary function values with spinal immobilization over time. The Wilcoxon test was used to compare delta values of FEV1, FVC, and FEV1/FVC ratio over time for 0-degree and 20-degree spinal immobilization. A p-value of less than.05 was considered statistically significant.

Results

The mean age of volunteers was 34.7 +- 5.08; 6 volunteers (20%) were female. The median BMI value was 32.56 (IQR 31.73-34.55). Median female WHR was 0.93 (IQR 0.90-0.97), and median male WHR was 1.0 (IQR 0.97-1.02).

Changes over time in FEV1 and FVC values and FEV1/FVC ratios during spinal immobilization at 0? and 20? were compared to base- line levels in the sitting position. The results a showed statistically significant decline in all pulmonary function test values for both situations following spinal immobilization (p < .001) (Table 1). However, there was no significant difference between values at 0 and 30 min of spinal immobilization for either 0-degree or 20- degree spinal immobilization (p > .05).

We also compared the decrease over time in FEV1 and FVC levels and FEV1/FVC ratios (DFEV1, DFVC, and DFEV1/FVC ratio) during spinal immobilization at 0? and 20?. Delta values were sim- ilar in both groups (Table 2).

Discussion

The study yielded two important findings. First, spinal immobi- lization with LBB and CC at both 0? and 20? caused a decrease in FEV1 and FVC values and FEV1/FVC ratio as compared to baseline levels for obese volunteers measured in sitting position. A second finding answers one of our main questions; if spinal immobiliza- tion performed at 20?, it was possible to reduce the decrease on pulmonary dynamics for obese subjects comparing the spinal immobilization performed at traditional 0?. Contrary to expecta- tion, reductions in spirometric values following spinal immobiliza- tion at 20? were similar to immobilization at 0? for obese volunteers. As the main cause of obesity’s negative effect on breathing is reduced respiratory compliance [15], one possible explanation is that spinal immobilization at 20? may be insufficient to reduce the negative effect of abdominal obesity on pulmonary functions. It follows that these results might change if spinal immobilization was performed at a higher angle (i.e., >20).

Obese trauma patients’ respiratory functions at baseline there- fore demonstrating a benefit of 20? spinal immobilization over 0? spinal immobilization would be an import finding. However, our results showed no significant conservative effect of spinal immobi- lization at 20? for this sample. It is possible that immobilization at a higher angle might show an improvement.

The restrictive effect of spinal immobilization on pulmonary functions was first demonstrated by Bauer et al. in 1988. Using a ZEE extrication device and LBB for immobilization, their results

Fig. 1. A, Picture showed classical spinal immobilization with long backboard (LBB) and cervical collar (CC) at 0? line position. B, Picture showed spinal immobilization at 20?.

Table 1

Changes over time in FEV1 and FVC values and FEV1/FVC ratios during SI at 0? and 20? were compared to baseline levels. All values were presented as median (IQR%25-%75).

Basal level (sitting position) 0th minute (after SI) 30th minute (after SI) p^a

At 0?	FEV1	3.52 (2.92-4.02)	3.08 (2.83-3.66)	3.13 (2.48-3.69)	<.001
	FVC	4.57 (3.81-4.98)	4.19 (3.53-4.77)	4.35 (3.58-4.84)	<.001
	FEV1/FVC	81.50 (72.75-86.25)	80.50 (71.00-84.25)	77.50 (69.00-82.00)	<.001
At 20?	FEV1	3.59 (2.94-4.03)	3.41 (2.75-3.84)	3.07 (2.70-3.75)	<.001
	FVC	4.64 (3.82-4.92)	4.49 (3.59-4.76)	4.28 (3.50-4.72)	<.001
	FEV1/FVC	81.00 (76.75-86.00)	79.50 (71.75-85.00)	80.00 (70.75-84.00)	<.001

Abbreviation: FEV1; forced expiratory volume in 1 s, FVC; forced vital capacity, SI; spinal immobilization, IQR; inter quartile range.

^a This difference is due to the decrease at pulmonary functions after SI compared to basal levels; otherwise there was no significant difference between the values after SI over time.

Table 2

The decrease over time in FEV1 and FVC levels and FEV1/FVC ratios (DFEV1, DFVC, and DFEV1/FVC ratio) during SI at 0? and 20?. All values were presented as median (IQR%25-% 75).

		0? SI	20? SI	p
DFEV1	0th minute – basal level	–0.29 [–040 to –0.12]	–0.19 [–0.42 to –0.09]	.254
	30th minute – basal level	–0.29 [–0.50 to –0.12]	–0.25 [–0.51 to –0.11]	.586
	30th minute – 0th minute	–0.06 [–0.18 to 0.20]	–0.05 [–0.22 to 0.04]	.289
DFVC	0th minute – basal level	–0.20 [–0.35 to –0.09]	–0.12 [–0.25 to –0.05]	.075
	30th minute – basal level	–0.17 [–0.38 to –0.06]	–0.24 [–0.34 to –0.08]	.902
	0th minute – 30th minute	0.06 [–0.14 to 0.17]	–0.07 [–0.26 to 0.07]	.218
DFEV1/FVC	0th minute – basal level	–2.00 [–4.00 to 0.00]	–2.00 [–5.00 to 0.00]	.759
	30th minute – basal level	–2.00 [–4.25 to –1.00]	–3.00 [–6.50 to –1.00]	.782
	30th minute – 0th minute	–1.00 [–2.25 to 2.25]	–1.00 [–3.00 to 0.50]	.671

Abbreviation: FEV1; forced expiratory volume in 1 s, FVC; forced vital capacity, SI; spinal immobilization, IQR; inter quartile range, D; delta.

showed a significant decrease in FEV1 and FVC values in both sit- uations, but FEV1/FVC ratio was not significantly altered [18]. Ala et al. demonstrated that CC application had a significant reducing effect on pulmonary volumes, including FEV1, FVC, and FEV1/FVC ratio [11]. Similar results were obtained in other studies using dif- ferent immobilization techniques [7,19,20]. In our recent study, we demonstrated that spinal immobilization at 20? rather than the traditional 0? had reduced the decrease caused by spinal immobi- lization on FEV1 and FVC values. We explained this by suggesting that immobilization at 20? more closely approximates the usual anatomical position of the lungs than the supine position [7]. How- ever, all of those studies were conducted with healthy participants; a strength of the present study is that it was conducted with obese volunteers.

Pulmonary functions are adversely affected by obesity itself, and immobilization would worsen that negative impact. The major effect of obesity is to reduce total respiratory system compliance, producing a narrowing of the airway and increasing respiratory system resistance [15]. As this reduced compliance is a conse- quence of fat deposition in the mediastinum and abdominal cavi- ties, fat distribution is a more important predictor of pulmonary functions than BMI alone [21,22]. Reduced compliance leads to reduction in expiratory reserve volume (ERV) and functional resid- ual capacity (FRC) [15]. However, other studies have demonstrated that obesity does not significantly affect a patient’s ability to fully inflate or deflate their lungs, and dynamic measures such as FEV1, FVC, and FEV1/FVC ratio were unaffected or only slightly reduced by obesity [21]. For that reason, respiratory system impedance may provide a more sensitive measure of obesity-related lung dys- function than spirometry alone, and there is a need for further research on the pulmonary effects of spinal immobilization in obese patients that includes impedance measurements and immo- bilization at higher angles.

Conclusion

The present findings confirm that spinal immobilization reduces pulmonary functions in obese volunteers, including

FEV1, FVC and FEV1/FVC ratio, and that 20-degree immobilization has no conservative effect on these values when compared to the traditional 0-degree immobilization. On the other hand, it may be that 20? is insufficient to decrease the negative effect of abdomi- nal obesity on pulmonary functions, and that impedance mea- surements should be performed in combination with spirometric evaluation for more accurate results. As the potential conservative effect of higher-degree spinal immobilization is cru- cial for trauma patients, there is a need for further research in this regard.

Limitations

This study had some limitations. First, we did not employ a con- trol group of healthy volunteers with normal BMI and also only six of our volunteers were female, because in that age group pure android type obesity is very rare and most of the time pre- menopausal females have gynoid type obesity or comorbid dis- eases that cause android type obesity. Secondly, we measured only spirometric values, and more accurate results might be obtained if impedance measurements were also performed. Finally, the results might have differed if participants with higher BMI were recruited, or if immobilization had been performed at a higher angle.

Conflict of interest

No conflict of interest was declared by the authors. The authors alone are responsible for the content and writing of the manuscript.

Ethics committee approval

The local ethical committee was approved this study (Kecioren Training and Research Hospital 2012-KAEK-15/1778).

Informed consent

Written informed consent was obtained from volunteers who participated in this study.

Author contributions

conceived and designed the experiments; S KC, GC

performed the experiments; GC, OLD

analyzed and interpreted the data; GC, S KC

contributed reagents, materials, analysis tools or data; GC, S KC, YC

wrote the paper GC, S KC

Acknowledgements

None.

Financial disclosure

None and no funding was obtained.

References

1. Hood N, Considine J. Spinal immobilisaton in pre-hospital and emergency care: a systematic review of the literature. Australas Emerg Nurs J 2015;18:118-37.
2. Walters BC, Hadley MN, Hurlbert RJ, Aarabi B, Dhall SS, Gelb DE, et alAmerican Association of Neurological Surgeons, Congress of Neurological Surgeons. Guidelines for the management of acute cervical spine and spinal cord injuries: 2013 update. Neurosurgery 2013;60(Suppl. 1):82-91.
3. Kwan I, Bunn F, Roberts I. Spinal immobilisation for trauma patients. Cochrane Database Syst Rev 2001;2:CD002803.
4. National Association of EMS Physicians, American College of Surgeons Committee on Trauma. EMS spinal precautions and the used of the long backboard. Prehosp Emerg Care 2013;17:392-3.
5. Deasy C, Cameron P. Routine application of cervical collars–what is the evidence? Injury 2011;42:841-2.
6. Corbaciog?lu S K, Akkus S , Cevik Y, Akinci E, Uzunosmanog?lu H. Effect of spinal immobilization with long backboard and cervical collar on vital signs. Eur J Emerg Med 2016;15:65-8. https://doi.org/10.5152/eajem.2016.32757.
7. Ay D, Aktas C, Yes ilyurt S, Sarikaya S, Cetin A, Ozdog?an ES. Effects of spinal immobilization devices on pulmonary function in healthy volunteer individuals. Ulus Travma Acil Cerrahi Derg 2011;17:103-7.
8. Ham HW, Schoonhoven LL, Galer AA, Shortridge-Baggett LL. Cervical collar- related pressure ulcers in trauma patients in intensive care unit. J Trauma Nurs 2014;21:94-102.
9. Mobbs RJ, Stoodley MA, Fuller J. Effect of cervical hard collar on intracranial pressure after head injury. ANZ J Surg 2002;72:389-91.
10. Totten VY, Sugarman DB. Respiratory effects of spinal immobilization. Prehosp Emerg Care 1999;3:347-52.
11. Ala A, Shams-Vahdati S, Taghizadieh A, Miri SH, Kazemi N, Hodjati SR, et al. Cervical collar effect on pulmonary volumes in patients with trauma. Eur J Trauma Emerg Surg 2016;42(5):657-60.
12. Akkus S , Corbaciog?lu S K, Cevik Y, Akinci E, Uzunosmanog?lu H. Effects of spinal immobilization at 20? on respiratory functions. Am J Emerg Med 2016;34 (10):1959-62.
13. Aksel G. Effects of spinal immobilization at a 20? angle on cerebral oxygen saturations measured by INVOS^TM. Am J Emerg Med 2018;36:84-7.
14. Ozdog?an S, Gokcek O, Katirci Y, Corbaciog?lu S K, Emektar E, Cevik Y. The effects of spinal immobilization at 20? on intracranial pressure. Am J Emerg Med 2019;37(7):1327-30.
15. Littleton SW. Impact of obesity on respiratory function. Respirology 2012;17 (1):43-9.
16. Waist circumference and waist-hip ratio: report of a WHO expert consultation Geneva, 8-11 December 2008.
17. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi V, Coates A, et al. Standardization of spirometry. Eur Respir J 2005;26:319-38. https://doi.org/ 10.1183/09031936.05.0003480520.
18. Bauer D, Kowalski R. Effect of spinal immobilization devices on pulmonary function in the healthy, nonsmoking man. Ann Emerg Med 1988;17(9) (915- 821).
19. Schafermeyer RW, Ribbeck BM, Gaskins J, Thomason S, Harlan M, Attkisson A. Respiratory effects of spinal immobilization in children. Ann Emerg Med 1991;20(9):1017-9.
20. RasalCarnicer M, Juguera Rodriquez L, Vela de Oro N, Garcia Perez AB, Perez Alonso N, Pardo Rios M. Differences in lung function after the use of 2 extrication systems: a randomized crossover trial. Emergencias 2018;30

    (2):115-8. Abr.

    Dixon AE, Peters U. The effect of obesity on lung function. Expert Rev Respir Med 2018;12(9):755-67. https://doi.org/10.1080/17476348.2018.1506331.

21. Collins LC, Hoberty PD, Walker JF, Fletcher EC, Peiris AN. The effect of body fat distribution on pulmonary function tests. Chest 1995;107(5):1298-302.