the most important factor in improving the outcome of a patient with out - of - hospital cardiopulmonary arrest ( ohcpa ) is cardiopulmonary resuscitation ( cpr ) performed by lay persons ( bystanders ) on the scene before contact with an organized emergency medical service ( ems ) .
however , insufficient knowledge concerning the confirmation of ohcpa , risks , and complications of cpr may be one of obstructive factors for immediate cpr .
non - trained lay persons tend to be particularly reluctant to perform immediate and aggressive cpr on patients who are not clearly suffering cpa , such as patients with normal body temperature , patients who were active until a few minutes before sudden collapse , or patients who appear to breathe or be able to move . lay persons can not easily recognize these cases as ohcpa , and they may be afraid of complications due to unnecessary cpr if the patient is not ohcpa , which may be harmful to the patient
it is clear that fear of complications of cpr may delay immediate recognition of ohcpa and the initiation of cpr .
however , there have been few reports concerning the risks and complications of bystander cpr for unconscious non - cpa patients outside a hospital and with respiratory arrest or inadequate respiration that have been widely known and accepted .
the object of the present study was to clarify the complications that may arise in such cases and the safety of bystander cpr , and to examine the role of immediate bystander cpr .
in japan , an out - of - hospital ems system has been established by the ambulance service and emergency life - saving technicians ( elsts ) belonging to the fire department and supported by in - hospital emergency departments ( eds ) .
the license of elst was established in 1991 . in yokohama city , pre - hospital and interhospital ems
systems have also been established for critical and severe patients , including those with ohcpa .
yokohama is the second largest city in japan , and our institute is located in its center .
the surface area and population of yokohama are 434 km and 3.37 million , respectively .
we selected 12 hospitals whose eds can receive and treat the most severe patients , including ohcpa patients , and who must accept all patients with ohcpa regardless of their capacity .
the medical doctor who is the ems director belongs to the 12 hospitals and carries out his duties in the central operation center of the city fire department ; the director advises elsts at the scene , decides how patients should be treated by elsts and oversees the transfer of ohcpa patients to the hospital .
any ohcpa patient is transferred to the nearest ed of the 12 hospitals [ figure 1 ] , except those who was diagnosed in some hospital and are expected to die in the near future , who are transferred to the hospital and for whom a death certificate can be written . for all hospitals ,
including ours , all data concerning unexpected ohcpa patients are population - based.[46 ] the number of cases who underwent cpr and cases with ohcpa a working group of the medical control ( mc ) committee of yokohama city , which includes some of these ems directors , has trained fire department members in the protocol of telephone advice on cpr by call takers and dispatchers so that they may offer telephone cpr ( t - cpr ) . until 2006 , following the old protocol for t - cpr , when ems callers and dispatchers received emergency calls about suspected ohcpa , they gave instructions for standard cpr ( mouth - to - mouth ventilation plus chest compression , consisting of 2 ventilations alternating with 15 compressions ) , or compression - only cpr if the caller rejected or was reluctant to perform mouth - to - mouth ventilation ; these instructions were given independent of the condition of the patient , caller or scene , except where there was difficulty in communication . since 2006 , following the new protocol for t - cpr , instructions are given for chest compression - only cpr without mouth - to - mouth ventilation . in our medical dispatching system , one dispatcher or call taker interviews the caller about the condition of the patient and gives instructions for t - cpr , while another sends the ambulance team to the scene .
this study was a population - based observational case series in the single center that examined data from april 2004 to march 2010 .
the subjects were patients who underwent cpr with chest compression by lay persons not belonging to any organized ems , regardless of their training in cpr or whether advised by t - cpr .
the subjects also had to be confirmed as non - ohcpa patients and had to have not undergone any cpr by any organized ems such as an ambulance team .
therefore , the subjects underwent just a short duration of cpr before contact with ems and confirmation as non - cpa by ems .
patients with ohcpa diagnosed after contact with an ems team and patients who received only a precordial thump , tapping of the back or heimlich maneuver without chest compression were excluded .
complications of bystander cpr included rib fracture , lung injuries such as pneumothorax and lung contusion , abdominal organ injuries such as hepatic , splenic and gastric injuries , and chest and/or abdominal pain requiring analgesics . in our ed , one medical doctor gathered information on the patient as in detail as possible from the ems ambulance team , the patient 's family or bystanders , and if necessary , the patient 's family doctor and the ems dispatcher in the central operation center , without directly treating the patient ; these data and information were entered into the patient 's medical record using a special format and in detailed writing .
other medical doctors in the ed checked symptoms and physical findings , and performed x - ray and blood examinations , electrocardiograms , and chest and abdominal ultrasonography in all cases , as well as other advanced examinations on demand such as computed tomography ( ct ) scans .
no clinical but practically unnecessary examinations were carried out solely to identify complications , such as simple x - ray examinations other than chest x - ray , chest ct , consecutive electrocardiograms or troponin i assay .
in japan , an out - of - hospital ems system has been established by the ambulance service and emergency life - saving technicians ( elsts ) belonging to the fire department and supported by in - hospital emergency departments ( eds ) .
the license of elst was established in 1991 . in yokohama city , pre - hospital and interhospital ems
systems have also been established for critical and severe patients , including those with ohcpa .
yokohama is the second largest city in japan , and our institute is located in its center .
the surface area and population of yokohama are 434 km and 3.37 million , respectively .
we selected 12 hospitals whose eds can receive and treat the most severe patients , including ohcpa patients , and who must accept all patients with ohcpa regardless of their capacity .
the medical doctor who is the ems director belongs to the 12 hospitals and carries out his duties in the central operation center of the city fire department ; the director advises elsts at the scene , decides how patients should be treated by elsts and oversees the transfer of ohcpa patients to the hospital .
any ohcpa patient is transferred to the nearest ed of the 12 hospitals [ figure 1 ] , except those who was diagnosed in some hospital and are expected to die in the near future , who are transferred to the hospital and for whom a death certificate can be written . for all hospitals ,
including ours , all data concerning unexpected ohcpa patients are population - based.[46 ] the number of cases who underwent cpr and cases with ohcpa a working group of the medical control ( mc ) committee of yokohama city , which includes some of these ems directors , has trained fire department members in the protocol of telephone advice on cpr by call takers and dispatchers so that they may offer telephone cpr ( t - cpr ) . until 2006 , following the old protocol for t - cpr , when ems callers and dispatchers received emergency calls about suspected ohcpa , they gave instructions for standard cpr ( mouth - to - mouth ventilation plus chest compression , consisting of 2 ventilations alternating with 15 compressions ) , or compression - only cpr if the caller rejected or was reluctant to perform mouth - to - mouth ventilation ; these instructions were given independent of the condition of the patient , caller or scene , except where there was difficulty in communication . since 2006 , following the new protocol for t - cpr , instructions are given for chest compression - only cpr without mouth - to - mouth ventilation . in our medical dispatching system , one dispatcher or call taker interviews the caller about the condition of the patient and gives instructions for t - cpr , while another sends the ambulance team to the scene .
this study was a population - based observational case series in the single center that examined data from april 2004 to march 2010 .
the subjects were patients who underwent cpr with chest compression by lay persons not belonging to any organized ems , regardless of their training in cpr or whether advised by t - cpr .
the subjects also had to be confirmed as non - ohcpa patients and had to have not undergone any cpr by any organized ems such as an ambulance team .
therefore , the subjects underwent just a short duration of cpr before contact with ems and confirmation as non - cpa by ems .
patients with ohcpa diagnosed after contact with an ems team and patients who received only a precordial thump , tapping of the back or heimlich maneuver without chest compression were excluded .
complications of bystander cpr included rib fracture , lung injuries such as pneumothorax and lung contusion , abdominal organ injuries such as hepatic , splenic and gastric injuries , and chest and/or abdominal pain requiring analgesics . in our ed , one medical doctor gathered information on the patient as in detail as possible from the ems ambulance team , the patient 's family or bystanders , and if necessary , the patient 's family doctor and the ems dispatcher in the central operation center , without directly treating the patient ; these data and information were entered into the patient 's medical record using a special format and in detailed writing .
other medical doctors in the ed checked symptoms and physical findings , and performed x - ray and blood examinations , electrocardiograms , and chest and abdominal ultrasonography in all cases , as well as other advanced examinations on demand such as computed tomography ( ct ) scans .
no clinical but practically unnecessary examinations were carried out solely to identify complications , such as simple x - ray examinations other than chest x - ray , chest ct , consecutive electrocardiograms or troponin i assay .
during the study period , 26 cases met the criteria for inclusion in our study .
the patients mean age was 69.0 years old ( ranging from 25 to 97 ) and the male : female ratio was 15:11 . in this period , we experienced 1,844 patients with ohcpa who underwent cpr by organized ems members and hospital staffs , and 884 of them ( 47.9% ) underwent bystander cpr .
we also experienced 910 patients who underwent bystander cpr , 884 of them ( 97.1% ) were confirmed as ohcpa by organized ems and 26 ( 2.9% ) were confirmed as non - ohcpa by organized ems [ figure 1 ] .
chest compression ( cc)-only cpr was performed in 21 cases and standard cpr ( cc and ventilation ) was performed in 5 cases .
the mean duration of bystander cpr was 6.5 minutes ( ranging from 1 to 26 minutes ) with 10 cases ( 38.5% ) over 7 minutes and 3 ( 11.5% ) over 10 minutes [ figure 2 ] .
nine patients died : 7 of intracranial hemorrhage and 1 of acute chronic congestive heart failure ( all of a causative pathological condition of unconsciousness ) , and 1 died of pneumonia secondary to unconsciousness .
the neurological condition at discharge of 8 patients ( 30.8% ) was the same as that just before the event , 5 patients ( 19.2% ) had mild disorder , 2 ( 7.7% ) had severe disorder , and the remaining 4 ( 15.4% ) had vegetative state .
all neurological disorders were due to the causative etiology of the unconsciousness , such as subarachnoid hemorrhage , massive cerebral infarction , etc . , or due to hypoxic brain damage during respiratory arrest .
the duration of bystander cpr and complication ; cc means chest compression and mmv means mouth - to - mouth ventilation , and foot note shows detail of cases with complications three cases ( 11.5% ) suffered from symptoms which can be thought as complications related to bystander cpr .
the rate of complications was evaluated 11.5% at most . in one case , we found tracheal bleeding without preceding hemoptysis immediately following tracheal intubation in the ed without any resistance during the procedure , however the bleeding was minimal and easily controlled with positive pressure mechanical ventilation for insufficient respiration due to neck hanging . in another case , we found minor gastric mucosal laceration during gastrointestinal fiberscopy for examination and treatment of hematemesis , which showed active bleeding from a chronic gastric ulcer in addition to the fresh minor laceration . in the remaining case ,
we found chest pain upon inspiration , indicating a minor rib fracture or muscular damage ; this was easily controlled with analgesics [ figure 2 ] .
although cpr performed by lay persons ( bystanders ) is extremely important to improve the outcome of patients with ohcpa , bystanders are not always able or willing to perform immediate , accurate , and high - quality cpr if they feel they have inadequate knowledge concerning appropriate cpr techniques .
bystanders can be supported to perform appropriate cpr by prior education , such as training courses or by direct advice at the time of the event , such as t - cpr .
call takers or dispatchers can not confirm a patient as cpa , however , nor can they support bystander cpr with full confidence if they lack adequate knowledge of the risks and complications of cpr , particularly cpr for non - ohcpa patients . likewise , cpr educators for lay citizens and for call takers and dispatchers are also hindered in the education and training they offer if they do not have adequate knowledge concerning the risks and complications of cpr , particularly cpr for non - cpa patients .
thus , accurate information concerning the risks and complications of cpr will be helpful to bystanders , call takers , and their educators so that they may be more able to immediately identify ohcpa and perform cpr , resulting in an improvement in the prognosis of ohcpa in the district .
moreover , it is more important to perform immediate cpr on patients who can not be clearly identified as ohcpa than for those with obvious cpa .
however , bystanders tend to be reluctant to perform immediate cpr for unconscious patients with inadequate respiration due to fear of misidentification of ohcpa , and because of the potential risks and complications of cpr . to eliminate hesitation in carrying out immediate and aggressive cpr , to increase the likelihood of bystander cpr for ohcpa patients and to improve the outcome of patients with ohcpa , it is important to clarify these issues and educate the public about the low occurrence of complications in bystander cpr , the easy treatability of these complications , and the safety of bystander cpr , particularly cpr for non - ohcpa patients .
the guarantee of minimal risk of complications of bystander cpr can make bystanders more willing to perform immediate cpr even when they can not confirm the patient as ohcpa . this guarantee can also help call takers or dispatchers of regional ems teams in providing t - cpr with full confidence , and can assist all cpr educators of anyone associated with bystander cpr .
our data indicate a very low occurrence of complications of cpr in non - ohcpa patients .
white et al . also reported that 12% of non - cpa patients who underwent cpr experienced discomfort and only 2% suffered a fracture , and no patients suffered visceral organ injury , in which study they did not specifically mandate chest x - ray or other diagnostic evaluations that might be directed toward complete ascertainment of cpr injury . in our present study , there still remained possibility of overlook of minor rib or sternal fracture , minor liver injuries without intra - abdominal bleeding , minor lung contusion without airway bleeding , minor gastric mucosal injuries without hematemesis , or asymptomatic complications , by chest and abdominal x - ray , chest - abdominal ultrasonography , electrocardiography and blood tests as routine examinations in our ed for all critical patients .
it must be noted , however , that the objective of the present study was not to clarify the occurrence of simply anatomical complications that may cause bystanders to hesitate to perform cpr , but to examine the safety of cpr for non - ohcpa patients .
many authors have shown a higher rate of occurrence of complications of cpr in ohcpa , including rib or sternal fracture , lung contusions , and liver or gastric injuries .
reported that 86% of rib fractures found during autopsy were missed by simple chest x - ray examination .
however , the duration of cpr in our study was short , possibly because in non - ohcpa patients , it must be terminated when the ems team assumes responsibility for the patient .
complications are reported to be more likely with prolonged chest compressions because of increasing fatigue and decreasing attention of the rescuer , deteriorating the quality of the compressions.[1012 ] one of the limitations of this study is that we can not confirm the ohcpa or non - ohcpa status of the patient before ems contact with the patient .
it is possible that the subjects include patients with ohcpa at the time of the event but who achieve return of spontaneous circulation ( rosc ) with bystander cpr before the arrival of the ems team .
another limitation is that this study was very small in size because of the extremely low frequency of t - cpr for non - ohcpa patients in our district , which is due to our protocol of the call takers for identifying ohcpa .
the third limitation is that there is no way to ascertain the direct association of three pathological conditions with bystander cpr , which we presented as complications of cpr
tracheal bleeding just after tracheal intubation without any resistance indicated the high possibility that the injury occurred not during but before the procedure of intubation .
tracheal bleeding or lung injury is commonly seen in patients with prolonged cpa in ed who underwent aggressive cpr for long duration .
fresh minor gastric mucosal laceration indicated the possibility that the injury occurred during cpr but there was also possibility that the injury had occurred before cpr .
however , in this study , we used in - hospital data of single center evaluated and written by medical doctors , which could certify high quality of the data in the view point of accuracy and detail .
additionally , our data do not include the risks and complications of cpr for ohcpa patients or those of cpr in a hospital and performed by an organized medical resuscitation team .
nevertheless , our data do indicate the extremely low frequency of lethal complications of cpr for non - ohcpa patients as well as the ease of treating complications of bystander cpr , both of which can encourage bystanders to perform cpr and call takers to assist bystanders in performing cpr on unconscious patients with inadequate respiration .
the risks and frequency of complications of bystander cpr are thought to be very low .
it is reasonable to perform immediate cpr on unconscious victims with inadequate respiration , and to help bystanders perform cpr using the t - cpr system .
immediate cpr or t - cpr for these victims can thus be performed promptly and confidently .
 background : insufficient knowledge of the risks and complications of cardiopulmonary resuscitation ( cpr ) may be an obstructive factor for cpr , however , particularly for patients who are not clearly suffering out of hospital cardiopulmonary arrest ( oh - cpa ) . 
 the object of this study was to clarify the potential complication , the safety of bystander cpr in such cases.materials and methods : this study was a population - based observational case series . to be enrolled , 
 patients had to have undergone cpr with chest compressions performed by lay persons , had to be confirmed not to have suffered ohcpa . 
 complications of bystander cpr were identified from the patients medical records and included rib fracture , lung injury , abdominal organ injury , and chest and/or abdominal pain requiring analgesics . in our emergency department , 
 one doctor gathered information while others performed x - ray and blood examinations , electrocardiograms , and chest and abdominal ultrasonography.results:a total of 26 cases were the subjects . 
 the mean duration of bystander cpr was 6.5 minutes ( ranging from 1 to 26 ) . 
 nine patients died of a causative pathological condition and pneumonia , and the remaining 17 survived to discharge . 
 three patients suffered from complications ( tracheal bleeding , minor gastric mucosal laceration , and chest pain ) , all of which were minimal and easily treated . 
 no case required special examination or treatment for the complication itself.conclusion:the risk and frequency of complications due to bystander cpr is thought to be very low . 
 it is reasonable to perform immediate cpr for unconscious victims with inadequate respiration , and to help bystanders perform cpr using the t - cpr system . 
INTRODUCTION
MATERIALS AND METHODS
Emergency medical service system in the study area
Study protocol and data collection
RESULTS
DISCUSSION
CONCLUSION