Emergency Medicine

High-quality cardiopulmonary resuscitation: we need to know more

Correspondence

Contents lists available at ScienceDirect

American Journal of Emergency Medicine

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

American Journal of Emergency Medicine 33 (2015) 1515-1535

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 \(INL\) 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

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