Correspondence

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American Journal of Emergency Medicine

journal homepage: www. elsevier. com/ locate/ajem

high-quality cardiopulmonary resuscitation: we need to know more

To the Editor,

In the August 2015 issue of the American Journal of Emergency De- partment, Soo Hoon Lee and his colleagues [1] have drawn the interest- ing and reasonable conclusion that current recommended chest compression depth (>= 50 mm), expressed only as absolute mea- surement, is not appropriate in all adults. Besides CC depth, emergency physicians should also raise concerns about 2010 cardiopulmonary re- suscitation (CPR) Guideline recommendations for CC location and compression-decompression time ratio, which also actually are not ap- propriately applied to all adults.

2010 CPR guidelines recommend the lower half of the sternum or the Internipple line as the hand positioning on the sternum for ex- ternal CC during CPR [2], In the light of its practicability, the latter posi- tion is preferable. However, emergency physicians must be aware of limitations if INL is considered as the landmark to locate hand position- ing. Shin et al [3] found that the intrathoracic structure underneath the INL was the Ascending aorta (18%), the root of aorta (48.7%), or the left ventricular outflow tract (12.7%), rather than the left ventricle itself (20.6%) in about 80% of 189 patients’ computed tomographic images. Cha et al [4] also found that the greater vascular area was compressed at INL during CPR, in comparison with that at sternoxiphoid junction and midpoint between INL and sternoxiphoid junction. Obviously, CC on the INL may result in left ventricular outflow tract obstruction, which leads to cardiac output decrease.

WE also call into question the 2010 CPR guidelines’ suggestion of compression time equal to decompression time. Let is illuminate the CPR theory through a physical point of view. The kinetic energy of blood flow which stems from CC during CPR conforms to energy conser- vation law: W = F * S = M * A * S = M * ?V/?T * S = E (W: work, F: force imposed on the chest, S: shift of the chest, M: quality of the chest, A: acceleration of chest movement, V: velocity of chest movement, T: time of CC, E: kinetic energy of blood flow). Based on aforementioned physical knowledge, we can easily deduce that the shorter compression time is, the more kinetic energy blood flow acquires. A shorter compression-decompression time ratio is quite possibly beneficial.

Of course, the above speculations need more robust evidence to sup- port, Lee and his colleagues rightly instruct us to interpret all CPR guide- lines prudently.

Wei Li, MD Xuezhong Yu^?

Emergency Department of Peking Union Medical College Hospital No. 1 Shuaifuyuan Wangfujing Dongcheng District

Beijing 100730, China

^?Corresponding author. Tel.: +86 10 13601262164

E-mail address: [email protected] http://dx.doi.org/10.1016/j.ajem.2015.07.080

References

1. Lee Soo Hoon, Kim Dong Hoon, Kang Tae-Sin, Kang Changwoo, Jeong Jin Hee, Kim Seong Chun, et al. The uniform chest compression depth of 50 mm or greater recom- mended by current guidelines is not appropriate for all adults. American Journal of Emergency Medicine 2015;33:1037-41.
2. Sayre MR, Hemphill R, Abella BS. Part 5: adult basic life support: 2010 International consensus on cardiopulmonary resuscitation and emergency cardiovascular care sci- ence with treatment recommendations. Circulation 2010;122:S298-324.
3. Shin J, Rhee JE, Kim K. Is the inter-nipple line the correct hand position for effective chest compression in adult cardiopulmonary resuscitation? Resuscitation 2007;75:305-10.
4. Cha KC, Kim YJ, Shin HJ, Cha YS, Kin H, Lee KH, et al. Optimal position for external chest compression during cardiopulmonary resuscitation: an analysis based on chest CT in patients resuscitated from cardiac arrest. Emerg Med J 2013;30:615-9.

CT versus grayscale rib series for the detection of rib fracture?

To the Editor,

In an article published in the April issue of your journal, Park et al [1] assessed the utility of inverted grayscale rib series (RS) in detecting rib fractures, and they found out that “inverted grayscale RS are not superior to conventional x-rays in detecting rib fractures but using both sets of images improved diagnostic sensitivity and accuracy among less experienced readers like medical students and junior EM residents”.

The gold standard in the diagnosis of rib fractures is chest computed to- mographic (CT) scan [1-4]. It has been stated that radiologists may over- look 40% of rib fractures on chest radiography [1,5,6]. However, they accepted “the diagnosis made by an experienced chest radiologist” as the standard of reference [1]. Although an experienced radiologist may diag- nose most of the rib fractures on RS, we think that a person cannot be the gold standard. It has been stated that chest X-rays miss more than 50% of the rib fractures, and Radiology reports often do not give the right information exactly with respect to the number and location of rib frac- tures [2]. It has also been stated that radiography, even with oblique views (RS), has a limited ability in detecting some anterior fractures [7]. It is difficult to diagnose anterior and, to a lesser extent, posterior rib frac- tures on conventional chest films including RS due to superposition of lung parenchyma. In fact, some regions of anterior parts of most of the ribs and costochondral junction often cannot be seen on chest films, so it is usually impossible to evaluate whether there is a fracture in these regions.

We, too, use inverted grayscale in our daily practice, and we see and believe that it is useful but we think that it would be better if Park et al accepted CT images as the standard of reference because the gold stan- dard imaging modality in the diagnosis of rib fractures is CT.

Harun Gunes, MD*

Department of Emergency Medicine, Duzce University School of Medicine

Duzce, Turkey

?Corresponding author at: Department of Emergency Medicine, Duzce University School of Medicine, 81620 Duzce, Turkey Tel.: +90 380 5421390/5940; fax: +90 380 5421387

Email address: [email protected]

? Conflicts of interest: The authors declared no conflicts of interest.

0735-6757/(C) 2015

Elif Nisa Unlu, MD

Department of Radiology, Duzce University School of Medicine

Duzce, Turkey

Ayhan Saritas, MD

Department of Emergency Medicine, Duzce University School of Medicine

Duzce, Turkey

http://dx.doi.org/10.1016/j.ajem.2015.07.061

References

1. Park JB, Cho YS, Choi HJ. Diagnostic accuracy of the inverted grayscale rib series for detection of rib fracture in minor chest trauma. Am J Emerg Med 2015;33(4): 548-52 [PubMed PMID: 25690384].
2. Livingston DH, Shogan B, John P, Lavery RF. CT diagnosis of Rib fractures and the prediction of acute respiratory failure. J Trauma 2008;64(4):905-11 [PubMed PMID: 18404055].
3. Cho SH, Sung YM, Kim MS. Missed rib fractures on evaluation of initial chest CT for trauma patients: pattern analysis and diagnostic value of coronal multiplanar recon- struction images with multidetector row CT. Br J Radiol 2012;85(1018):e845-50 [PubMed PMID: 22514102. Pubmed Central PMCID: 3474015].
4. Hoffstetter P, Dornia C, Schafer S, Wagner M, Dendl LM, Stroszczynski C, et al. Diag- nostic significance of rib series in minor thorax trauma compared to plain chest film and computed tomography. J Trauma Manag Outcomes 2014;8:10 [PubMed PMID: 25152770. Pubmed Central PMCID: 4141660].
5. Aukema TS, Beenen LF, Hietbrink F, Leenen LP. Initial assessment of chest x-ray in Thoracic trauma patients: awareness of specific injuries. World J Radiol 2012;4(2): 48-52 [PubMed PMID: 22423318. Pubmed Central PMCID: 3304093].
6. Griffith JF, Rainer TH, Ching AS, Law KL, Cocks RA, Metreweli C. Sonography compared with radiography in revealing acute rib fracture. AJR Am J Roentgenol 1999;173(6): 1603-9 [PubMed PMID: 10584808].
7. Hong TS, Reyes JA, Moineddin R, Chiasson DA, Berdon WE, Babyn PS. Value of post- mortem thoracic CT over radiography in imaging of pediatric rib fractures. Pediatr Radiol 2011;41(6):736-48 [PubMed PMID: 21264464].

THE AUTHOR REPLIES:

I agree that many radiologists overlook rib fractures on a chest x-ray, chest CT is more accurate for diagnosing rib fractures, and chest CT is more desirable as a gold standard in this study.

However, this study dealt with finding “rib fractures in an X-ray film”, not “real fractures including those invisible in X-ray films”. If there is only a vague fracture line in chest x-ray, most physicians (even radi- ologists) cannot find it before a CAT scan. Some rib fractures are invisible in chest x-ray. Besides, emergency Physicians and medical students who were relatively inexperienced on reading chest x-rays were enrolled on this study.

So while I think the radiologist’s opinion can be a gold standard, it’s not really not a limitation of this study. Th authors are trying to say, “inverted grayscale image can be helpful for little experienced clinicians to reach the radiologist’s level.”

Finally, I would note chest CT is not perfect for finding rib fractures.

Hyuk J Choi MD Emergency Department Hanyang University Republic of Korea

Delays and errors among pediatric residents during simulated resuscitation scenarios using pediatric advanced life support (PALS) algorithms

To the Editor,

The low prevalence of pediatric cardiopulmonary arrests presents clini- cal management challenges for inhospital first-line physicians, especially for pediatric residents who often act in this capacity without significant ex- perience [1]. A recent study showed that using simulation to provide resi- dent feedback on their performances during simulated mock codes significantly correlates with improved pediatric patient cardiopulmonary

arrest survival rates [2]. Knowledge of the deviations from ideal manage- ment would identify opportunities to improve Clinical performances in resuscitation. We aimed to identify clinically significant delays and errors on a series of specific actions during 5 simulated resuscitations performed by pediatric residents using validated scoring instruments [3,4].

We conducted a retrospective study of video-recorded resuscitation

performances before a Pediatric Advanced Life Support (PALS) course. A total of 24 junior and senior pediatric residents were videotaped performing a series of 5 standardized pediatric resuscitation scenario cat- egories given in random order (pulseless nonshockable arrest: asystole or pulseless electrical activity; shockable arrest: ventricular tachycardia or ventricular fibrillation; respiratory arrest, apnea, or postseizure; shock: hypovolemic shock or septic shock; and dysrhythmia: supraventricular tachycardia or stable ventricular tachycardia). Scenarios included a stan- dardized progression depending on the resident’s actions. Performances for each scenario were measured by a trained video reviewer using the Clinical Performance Tool [3]. This validated scoring instrument consists of a checklist of specific actions, identified as essential to perform during resuscitations requiring PALS algorithms according to 2005 American Heart Association PALS guidelines [5]. Only pulseless shockable and nonshockable arrest scenarios were modified according to the 2010 AHA PALS guidelines resulting in very little change in the scoring instru- ment [4]. The primary analysis was the proportion of errors for each crit- ical task for each scenario. Delays and errors are defined in Table 1.

A major finding was that, across all scenarios, pulse check was delayed

by more than 30 seconds in 56% of participants (95% confidence interval [CI], 46%-66%). This finding highlights the importance of emphasizing quick clinical assessment and quality of Basic Life Support when teaching PALS. Another important finding was that all residents failed to ask for rapid dextrose check in shock scenarios (Table 2). This is important be- cause it has been reported that up to 30% of children in hypovolemic shock will present with hypoglycemia [5,6]. However, pediatric residents generally recognized the need to perform critical resuscitation actions such as cardiopulmonary resuscitation (CPR), defibrillation, cardioversion, or intravenous fluid bolus.

For pulseless shockable arrest scenarios, we found improper ventilation rates in 17% and improper compression rates in 4%. No CPR disruptions were reported. Nevertheless, 33% of participants (95% CI, 16%-55%) failed to identify correct rhythm on the monitor, and most pediatric residents did not deliver timely compressions or defibrillation in these situations. In- deed, 25% of residents (95% CI, 10%-47%) failed to start compressions, ap- proximately 20% of residents (95% CI, 5%-40%) used wrong energy doses whether it was for first or second shock delivery, and 4% (95% CI, 0%-21%) never defibrillated a patient with pulseless shockable arrest (Table 3).

For tachycardia with pulses and poor perfusion scenarios, clinical perfusion assessment was delayed by more than 60 seconds in 29% of scenarios (95% CI, 13%-51%) and was not assessed at all in an additional 17% of cases (95% CI, 5%-37%). Seventy-nine percent of residents (95% CI, 58%-93%) performed successful cardioversion once clinical deterioration occurred, whereas 8% of residents (95% CI, 1%-27%) never attempted to do so. Among those who performed cardioversion, 13% (95% CI, 3%-35%) attempted cardioversion with an unsynchronized mode, and 4% (95% CI, 0%-23%) used the wrong cardioversion dose (Table 4). In addition, 29% of residents (95% CI, 13%-51%) wrongly performed defibrillation on a pa- tient with pulseless nonshockable arrest (Table 5). Delays in these inter- ventions are consistent with recent pediatric literature [7,8]. Hunt et al

[8] showed that the only variable independently associated with time to defibrillation was previous experience with discharging a defibrillator on a human and/or a mannequin. This suggests that health care pro- viders and trainees should have hands-on experience with discharging defibrillator regularly during their Training and practice. Nevertheless, this study was conducted just before implementation of the 2010 PALS guidelines in our institution, which includes “CABs” instead of “ABCs.” It is possible that the increased emphasis on “circulation” for pulseless shockable and nonshockable arrests would have been associated with less delay in pulse check and in initiation of CPR.