Chest compressions: the good, the bad and the ugly.

Where exactly is the chest compression, where does it begin, hen does it end, how deep does it go and at what rate are they erformed? In short – how good or bad is the chest compression? hese are some of the questions researchers ask themselves repeatdly. As well as these data, we need to know the proportion of esuscitation time spent giving quality compressions, the ratio of nterruptions and several other parameters and we need to evalate the effect on survival. Considering the increasing capacity for ata storage and growing repositories of resuscitation data one ight also ask what proportion of valuable research time is spent n analysing compressions. In recent years there have been a growing number of research eports focussing on the quality of CPR. Studies based on data from esuscitation of cardiac arrest patients both inand out-of-hospital rovided evidence that resuscitation was not performed according o guidelines. In particular, interruptions in chest compressions and entilations were found to be frequent during CPR.1,2 Since then, researchers have developed quantitative measures o characterise chest compressions, such as CPR fraction, compresion depth, compression rate.3–5 The importance of quality CPR and he relevance of these parameters have been verified by researchers ho have related the quality parameters to changes in rates of urvival, return of spontaneous circulation (ROSC) or other clinical utcomes. The quality parameters give the researchers a valuable ool enabling success or failure to be related to specific compression echniques or other key elements of treatment.6–11 Modern defibrillators make all of this possible. Several manfacturers offer systems that also measure signals related to the escuer’s performance. In some devices an accelerometer, possibly ith force measurement capabilities, is placed on the sternum of he patient. The captured data have high resolution and each is typcally measured several hundred times per second, which provides ccurate information on the acceleration and force provided by the escuers’ hands.12 Both speed and position can be determined. The horacic impedance signal is measured by passing a current through he electrodes and is changed by compressions and by the volme changes associated with ventilations. The impedance signal ill indicate compression rate but not depth. Although, primarily howing the cardiac rhythm, the electrocardiogram (ECG) recordng can also indicate compressions, ventilations and defibrillations. n most studies, the quality data are derived by manual or semi utomatic review of these signals. Manual evaluation of individual hest compressions is usually used to obtain the quality parameers. This evaluation is often limited to the first few minutes of the pisodes. As the number of patients increase, the work involved ecomes substantial and requires a lot of the research time.