CHEST COMPRESSION INJURIES DETECTED VIA ROUTINE POST-ARREST CARE IN PATIENTS WHO SURVIVE TO ADMISSION AFTER OUT-OF-HOSPITAL CARDIAC ARREST Lori L. Boland, MPH, Paul A. Satterlee, MD, Jonathan S. Hokanson, MD, Craig E. Strauss, MD, MPH, Dana Yost, MICP tively associated with detected injury (OR = 7.86 [95% CI = 1.7–35.9] and 6.30 [95% CI = 2.6–15.5], respectively). Conclusion. In patients who survived OHCA to admission, longer duration of compressions and use of CT during the postarrest course were associated positively with documented compression injury. Compression-induced injuries detected via routine post-arrest care are likely to be largely insignificant in terms of length of recovery. Key words: cardiac arrest; cardiopulmonary resuscitation; chest compression; injuries; fractures; mechanical compression
Prehosp Emerg Care Downloaded from informahealthcare.com by Nyu Medical Center on 06/09/15 For personal use only.
ABSTRACT Objective. To examine injuries produced by chest compressions in out-of-hospital cardiac arrest (OHCA) patients who survive to hospital admission. Methods. A retrospective cohort study was conducted among 235 consecutive patients who were hospitalized after nontraumatic OHCA in Minnesota between January 2009 and May 2012 (117 survived to discharge; 118 died during hospitalization). Cases were eligible if the patient had received prehospital compressions from an emergency medical services (EMS) provider. One EMS provider in the area was using a mechanical compression device (LUCASTM ) as standard equipment, so the association between injury and use of mechanical compression was also examined. Prehospital care information was abstracted from EMS run sheets, and hospital records were reviewed for injuries documented during the post-arrest hospitalization that likely resulted from compressions. Results. Injuries were identified in 31 patients (13%), the most common being rib fracture (9%) and intrathoracic hemorrhage (3%). Among those who survived to discharge, the mean length of stay was not statistically significantly different between those with injuries (13.5 days) and those without (10.8 days; p = 0.23). Crude injury prevalence was higher in those who died prior to discharge, had received compressions for >10 minutes (versus ≤10 minutes) and underwent computer tomography (CT) imaging, but did not differ by bystander compressions or use of mechanical compression. After multivariable adjustment, only compression time > 10 min and CT imaging during hospitalization were posi-
PREHOSPITAL EMERGENCY CARE 2015;19:23–30
INTRODUCTION Compressing the chest during cardiopulmonary resuscitation (CPR) is essential for survival of cardiac arrest, but the practice is not devoid of risk. The potential for harm during CPR has been acknowledged since the inception of the technique, and unintended injuries have been described in the medical literature for decades.1–7 Skeletal chest fractures are the most common injuries incurred with compressions, with an estimated onethird of patients sustaining rib fractures and onefifth sustaining sternal fractures.4 Soft tissue and visceral injuries, such as liver and splenic lacerations, hemothorax, pneumothorax, retroperitoneal hemorrhage, pulmonary contusion, and cardiac and large vessel damage, have also been reported, but occur with much lower incidence, typically in the range of 0–5%.4,6–8 Despite the extensive literature on compression injuries, two notable deficiencies exist. First, data on CPR injuries in survivors of cardiac arrest remain scarce. Published studies have relied almost exclusively on postmortem examinations, and while crucial for describing lethal CPR injuries, these findings have limited use in establishing the extent of nonlethal complications in instances where such insults potentially have clinical relevance, that is, among survivors. Very few studies to date have documented compression injuries specifically in survivors of cardiac arrest9–11 and Perkins et al. recently noted that with regard to compression injuries, “survival and disability are the relevant endpoints.”12 Second, there is an emerging need for a systematic study of injuries associated with the novel mechanical compression devices that are becoming increasingly popular.12 Case reports
Received April 16, 2014 from the Division of Applied Research, Allina Health, Minneapolis, Minnesota (LLB), Allina Health Emergency Medical Services, St. Paul, Minnesota (LLB, PAS), Department of Emergency Medicine, Abbott Northwestern Hospital, Minneapolis, Minnesota (PAS, JSH), Minneapolis Heart Institute at Abbott Northwestern Hospital, Minneapolis, Minnesota (CES), and Redmond Fire Department, Medic One Division, King County, Washington (DY). Revision received May 13, 2014; accepted for publication May 21, 2014. Allina Health EMS received an educational grant and 6 LUCASTM devices as part of its participation in the North American LUCASTM Evaluation (NALE) study. Dr. Satterlee and Mr. Yost have received speaking honoraria from Physio-Control, Inc. The authors report no other conflicts of interest. Address correspondence to Lori L. Boland, MPH, Division of Applied Research, Allina Health, 2925 Chicago Avenue South, Minneapolis, MN 55407, USA. E-mail: [email protected] doi: 10.3109/10903127.2014.936636
23
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PREHOSPITAL EMERGENCY CARE
illustrating catastrophic injuries associated with their use have appeared in recent years,13–16 but similar injuries have also been described in the context of manual compression1,17–20 and systematic studies are needed. In this report, we describe injuries attributable to prehospital chest compressions that were documented during post-arrest hospitalization in cardiac arrest patients who survived to hospital admission. The use of mechanical compression in these cases is also detailed. Acknowledging that rare instances of lethal CPR-induced injury do occur, the objective was to characterize compression injuries detected via routine post-arrest care and understand their implications for complicating recovery after cardiac arrest.
MATERIALS AND METHODS Study Design and Setting Allina Health is a not-for-profit health system providing care to approximately 1.5 million residents in Minnesota and Wisconsin. The system uses an integrated electronic health record (EHR) across its inhospital and ambulatory care settings. It also includes an ambulance service, Allina Health Emergency Medical Services (AH-EMS), which responds to approximately 90,000 emergency calls annually and transports 60% of its patients to hospitals within the system. Two dozen other ambulance services transport patients to Allina hospitals. EMS run sheets from external prehospital agencies are scanned and uploaded into the system’s EHR. For this investigation, a retrospective cohort study was conducted among adult patients who had initially survived nontraumatic out-of-hospital cardiac arrest (OHCA) and were hospitalized between January 2009 and May 2012 at any of the 11 Allina hospitals. By 2009, AH-EMS had fully implemented use of the LUCASTM chest compression system (Physio-Control/Jolife AB, Lund, Sweden) as standard equipment and details of the protocol for device use have been previously described.21 In short, when use of the device is not contraindicated, placement is to occur as soon as possible, manual compressions are not to be delayed for the purpose of application, and pauses for application should be less than 10 seconds. Between 2010 and 2012, three other EMS providers in the area began sporadically using LUCASTM on an experimental basis.
Case Ascertainment Potential cases were identified by querying the EHR for patients with ICD-9 diagnosis codes indicative of cardiac arrest or ventricular fibrillation (i.e., 427.5 and 427.41) who had provided consent for the use of their data for research. To grossly filter out inhospital ar-
JANUARY/MARCH 2015
VOLUME 19 / NUMBER 1
rests, the qualifying code was required to be either the admitting diagnosis code or have a corresponding “present on admission” designation per CMS criteria. This initially yielded 616 potential cases, but upon preliminary chart review 376 were excluded because they did not reflect true OHCA, were the result of trauma, or did not involve prehospital chest compressions. A total of 240 cases remained for abstraction. The study was approved by the Allina institutional review board with a waiver of informed consent.
Data Collection and Measures Patient and event details were uploaded from the EHR into an online data collection tool. A single abstractor (LLB) reviewed all EMS run sheets and recorded EMS provider, bystander compressions (yes, no), duration of prehospital care (i.e., interval between EMS arrival at patient and patient arrival in ED), and use of mechanical compression (yes, no). Use of mechanical compression was defined as any use in the prehospital setting or in the ED. While patients with no mechanical compression received manual compressions exclusively, it is assumed those with mechanical compression received some manual compressions during their resuscitation (i.e., before device was placed). Precise cumulative compression time is not routinely recorded by paramedics, so all available time stamps in the prehospital record, including notations of periods of spontaneous circulation, were used to approximate and categorize total prehospital compression time as 20 minutes. Bystander compressions were not considered in the estimate of prehospital compression time, and where a reasonable estimate could not be made, compression time was categorized as unknown. Independently, two physicians (JSH, CES) each conducted a comprehensive review of the hospitalization records of half of the cases. All ED provider notes, imaging results, hospital course notes, and discharge summaries were examined for evidence of injuries that were most likely the result of chest compression. Fields in the data collection tool allowed the physicians to indicate rib fracture, sternal fracture, liver injury, splenic injury, pneumothorax, hemothorax, mediastinal hemorrhage, pericardial hemorrhage, pulmonary contusion, and thoracic artery injury, and other injuries not specified. Information about imaging and any post-EMS compressions performed in the hospital was also noted. Injuries were classified as life-threatening, consequential, or insignificant according to the following definitions used previously3 : life-threatening – reasonably expected to interfere with cardiovascular or respiratory function to the extent of depriving tissue of needed blood and oxygen, exsanguinations in excess of 800 mL; consequential – demands therapy for repair or for alleviation of pain, expected to prolong
L. L. Boland et al.
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CHEST COMPRESSION INJURIES
hospitalization; insignificant – requires no therapy (expected to heal spontaneously) or may require limited one-time only therapy. Physician reviewers were instructed to refrain from viewing EMS run sheets, but it was impossible to ensure blinding to EMS agency and use of mechanical compression as these are sometimes mentioned in hospital provider notes.
Prehosp Emerg Care Downloaded from informahealthcare.com by Nyu Medical Center on 06/09/15 For personal use only.
Analysis Patient and event characteristics were described using means and proportions. Frequencies and proportions were used to examine the prevalence of compressionrelated injuries overall, by discharge status, and by other covariates of interest. T-tests and Pearson chisquare statistics were used to evaluate differences in means and proportions, respectively. Fisher’s exact test was used when expected cell counts in contingency tables were less than 5. Logistic regression models were used to generate crude and adjusted odds ratios (and 95% confidence intervals) of any compression injury. All analyses were conducted with Stata 12.1.22
RESULTS Five cases were excluded from analysis because mechanical compression use could not be determined
definitively. Of the 235 remaining cases, 117 survived to discharge and 118 died during hospitalization. Patients were treated and transported by 31 different EMS providers. The LUCASTM device was used in 104 patients (44%), including 94 prehospital uses by 5 different EMS agencies (80 AH-EMS uses, 14 uses by other EMS agencies). In the remaining 10 patients, LUCASTM was used only in the ED by hospital staff. No references to other mechanical compression devices were found, but one patient did receive compressions with a hand-held, nonautomated active compression–decompression device. Patients who died prior to discharge were more likely to be female and over the age of 75 than those who ultimately survived (Table 1). Those who died were also more likely to have had compressions for >20 minutes and to have received mechanical compression. Chest radiography (CXR) was conducted in all but 6 patients, and echocardiograms were conducted in 81%. Use of computed tomography (CT) and cardiac magnetic resonance (MR) imaging were less common, and uses of MR occurred only among those who survived to discharge. Use of anticoagulants on admission was more prevalent in patients who died during hospitalization, perhaps reflecting more extensive comorbidities in this group. Length of hospital stay was statistically significantly shorter in patients
TABLE 1. Patient and event characteristics, overall and by discharge status Discharge Status Variable
All (n = 235)
Dead (n = 118)
Age, y Age ≥ 75 yrs Male Body-mass Index, kg/m2 Body-mass Index Category, kg/m2 Normal (30) Body Weight, kg Bystander compressions Mechanical compressionb Duration of prehospital care, min Total Compression Time 20 minutes Imaging during hospitalization Chest X-ray CT Cardiac MRI Echocardiogram Medications on admission Anticoagulants Steroids Osteoporosis medications Length of stay, days
64 (15) 27% (64) 62% (145) 28.8 (7)
67 (14) 35% (41) 53% (62) 28.6 (8)
60 (15) 20% (23) 71% (83) 29.1 (6)
29% (68) 33% (78) 38% (88) 85.9 (23) 27% (64) 44% (104) 35 (12)
34% (40) 27% (31) 39% (46) 83.9 (25) 27% (31) 55% (65) 38 (12)
24% (28) 40% (47) 36% (42) 87.9 (21) 28% (33) 33% (39) 32 (11)
9% (22) 23% (55) 29% (69) 34% (81)
3% (3) 17% (20) 27% (32) 50% (59)
16% (19) 30% (35) 32% (37) 19% (22)
97% (229) 36% (85) 12% (29) 81% (190)
97% (114) 36% (42) 0% (0) 71% (84)
98% (115) 37% (43) 25% (29) 91% (106)
0.68 0.85 < 0.001 < 0.001
20% (47) 5% (12) 2% (4) 7 (7)
30% (35) 8% (9) 3% (3) 4 (5)
10% (12) 3% (3) 1% (1) 11 (6)
< 0.001 0.14 0.62 < 0.001
Results a re expressed as mean (SD) or percent (n) CT = computed tomography; MRI = magnetic resonance imaging a t-test (continuous variable) or Pearson χ 2 (categorical variables) for difference by discharge status b LUCASTM device used to deliver mechanical compressions
Alive (n = 117)
P-Valuea
< 0.001 0.010 0.005 0.62
0.060 0.19 0.88 0.001 < 0.001
< 0.001
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TABLE 2. Frequency of chest compression injuries, overall and by discharge status
Prehosp Emerg Care Downloaded from informahealthcare.com by Nyu Medical Center on 06/09/15 For personal use only.
Discharge Status
Patients with any injury Injuries by Type Sternal fracture Rib fracture ≥ 3 rib fractures Liver injury Spleen injury Pneumothorax/Pneumomediastinum Pulmonary contusion Pericardial effusion Hemorrhage Mediastinal Pericardial Retro-/Intraperitoneal Hemothorax Thoracic artery injury
All (n = 235)
Dead (n = 118)
Alive (n = 117)
31 (13%)
22 (19%)
9 (8%)
2 (1%) 22 (9%) 19 (8%) 1 (0.4%) 0 4 (2%) 3 (1%) 1 (0.4%)
2 (2%) 18 (15%) 17 (14%) 0 0 3 (3%) 2 (2%) 0
0 4 (3%) 2 (2%) 1 (1%) 0 1 (1%) 1 (1%) 1 (1%)
4 (2%) 0 2 (1%) 1 (0.4%) 1 (0.4%)
3 (3%) 0 1 (1%) 0 0
1 (1%) 0 1 (1%) 1 (1%) 1 (1%)
who died prior to discharge (4 days vs. 11 days, p < 0.001), largely because a majority (74%; n = 87) were placed on comfort care shortly after admission. Compression-related injuries were documented in the hospital records of 31 patients (13%; Table 2), and the prevalence was higher among those who died during hospitalization (19% vs. 8%, p = 0.013). The most commonly noted injury was rib fracture (9%), and 86% of patients with rib fracture had >3 ribs involved. Sternal fractures were noted in only 2 patients (1%) and no splenic injuries were documented. Overall, compression-related fractures were documented in 22 patients (9%; both patients with sternal fractures also had rib fractures). Nonskeletal injuries were found in 13 patients (6%), with 1 patient sustaining four unique visceral injuries. Injuries were characterized as insignificant in just over half of patients with any injury detected (16/31; 52%). Details of the 15 cases who sustained injuries that were characterized as life-threatening or consequential are presented in Table 3. Only 3 patients (1.3%) suffered life-threatening CPR-related trauma that required additional intervention or imaging during hospitalization. One patient developed mediastinal hemorrhage, hemothorax, and bleeding from branches of the left internal mammary artery that required coil embolization 1 day after arrest (patient 1). In a second patient, a precipitous drop in hemoglobin led to an abdominal/pelvic CT that revealed a retroperitoneal bleed (patient 2). Blood transfusions were required to stabilize the patient, intravenous heparin was discontinued, and recovery was somewhat complicated. In a third patient who suffered an intraperitoneal hemorrhage, acute pulmonary embolism was the suspected cause of arrest, and the patient had received massive transfusions, tPA and heparin before ultimately expiring < 24 hours after admission (patient 5). Among survivors, the mean length of stay (±SD) was slightly
longer in those with injuries (13.5 ± 5 days vs. 10.8 ± 6 days), although the difference was not statistically significant (p = 0.23). Of the covariates examined, death during hospitalization, total compression time > 10 minutes, and CT imaging during hospitalization were all positively associated with detection of injury (Table 4). In the crude analysis, a slightly higher prevalence of injury was observed in patients who had received mechanical compressions, but there was also a strong positive association between use of mechanical compression and total compression time. Mechanical compressions were delivered in 55% of patients who received compressions for >10 minutes and in only 26% of patients with shorter compression times (p < 0.001). After adjustment for total compression time in multivariable models, there was no association between use of mechanical compressions and CPR-associated injury. In a logistic regression model that included discharge status, age, gender, use of mechanical compression, compression time > 10 minutes, and CT imaging, only compression time > 10 minutes and CT imaging were positively and statistically significantly associated with detection of injury, with adjusted odds ratios of 7.86 (95% CI = 1.7–35.9) and 6.30 (95% CI = 2.6–15.5), respectively.
DISCUSSION In this cohort of patients who survived OHCA to hospital admission, the overall prevalence of compression-related injuries recognized during routine post-arrest care was 13%. Rib fractures were documented in 9% of patients, sternal fractures in 1%, and nonskeletal injuries in 6%. Previous injury estimates derived primarily from autopsy studies vary dramatically – from 13 to 97% for rib fractures and 1
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TABLE 3. Characteristics of cardiac arrest patients with life-threatening or consequentiala compression injuries documented in the hospitalization record #
Gender
Age
Mechanical Compression
Patient Survived to Discharge 1 Male 81 No
2
Male
65
Yes
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3 Female 67 No 4 Male 66 Yes Patient Expired Prior to Discharge 5 Female 54 Yes 6 7 8
Bystander Compression
Compression Time (min)
Length of Stay (days)
Imaging Conducted
No
11–20
13
CXR, CT, E
Yes
11–20
16
CXR, CT, E
No Yes
11–20 11–20
13 23
CXR, E CXR, CT, E
No
20+
1
CXR
Male Female Male
60 61 66
No No No
No Yes No
Unknown 11–20 11–20
2
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ABSTRACT Objective. To examine injuries produced by chest compressions in out-of-hospital cardiac arrest (OHCA) patients who survive to hospital admission. Methods. A retrospective cohort study was conducted among 235 consecutive patients who were hospitalized after nontraumatic OHCA in Minnesota between January 2009 and May 2012 (117 survived to discharge; 118 died during hospitalization). Cases were eligible if the patient had received prehospital compressions from an emergency medical services (EMS) provider. One EMS provider in the area was using a mechanical compression device (LUCASTM ) as standard equipment, so the association between injury and use of mechanical compression was also examined. Prehospital care information was abstracted from EMS run sheets, and hospital records were reviewed for injuries documented during the post-arrest hospitalization that likely resulted from compressions. Results. Injuries were identified in 31 patients (13%), the most common being rib fracture (9%) and intrathoracic hemorrhage (3%). Among those who survived to discharge, the mean length of stay was not statistically significantly different between those with injuries (13.5 days) and those without (10.8 days; p = 0.23). Crude injury prevalence was higher in those who died prior to discharge, had received compressions for >10 minutes (versus ≤10 minutes) and underwent computer tomography (CT) imaging, but did not differ by bystander compressions or use of mechanical compression. After multivariable adjustment, only compression time > 10 min and CT imaging during hospitalization were posi-
PREHOSPITAL EMERGENCY CARE 2015;19:23–30
INTRODUCTION Compressing the chest during cardiopulmonary resuscitation (CPR) is essential for survival of cardiac arrest, but the practice is not devoid of risk. The potential for harm during CPR has been acknowledged since the inception of the technique, and unintended injuries have been described in the medical literature for decades.1–7 Skeletal chest fractures are the most common injuries incurred with compressions, with an estimated onethird of patients sustaining rib fractures and onefifth sustaining sternal fractures.4 Soft tissue and visceral injuries, such as liver and splenic lacerations, hemothorax, pneumothorax, retroperitoneal hemorrhage, pulmonary contusion, and cardiac and large vessel damage, have also been reported, but occur with much lower incidence, typically in the range of 0–5%.4,6–8 Despite the extensive literature on compression injuries, two notable deficiencies exist. First, data on CPR injuries in survivors of cardiac arrest remain scarce. Published studies have relied almost exclusively on postmortem examinations, and while crucial for describing lethal CPR injuries, these findings have limited use in establishing the extent of nonlethal complications in instances where such insults potentially have clinical relevance, that is, among survivors. Very few studies to date have documented compression injuries specifically in survivors of cardiac arrest9–11 and Perkins et al. recently noted that with regard to compression injuries, “survival and disability are the relevant endpoints.”12 Second, there is an emerging need for a systematic study of injuries associated with the novel mechanical compression devices that are becoming increasingly popular.12 Case reports
Received April 16, 2014 from the Division of Applied Research, Allina Health, Minneapolis, Minnesota (LLB), Allina Health Emergency Medical Services, St. Paul, Minnesota (LLB, PAS), Department of Emergency Medicine, Abbott Northwestern Hospital, Minneapolis, Minnesota (PAS, JSH), Minneapolis Heart Institute at Abbott Northwestern Hospital, Minneapolis, Minnesota (CES), and Redmond Fire Department, Medic One Division, King County, Washington (DY). Revision received May 13, 2014; accepted for publication May 21, 2014. Allina Health EMS received an educational grant and 6 LUCASTM devices as part of its participation in the North American LUCASTM Evaluation (NALE) study. Dr. Satterlee and Mr. Yost have received speaking honoraria from Physio-Control, Inc. The authors report no other conflicts of interest. Address correspondence to Lori L. Boland, MPH, Division of Applied Research, Allina Health, 2925 Chicago Avenue South, Minneapolis, MN 55407, USA. E-mail: [email protected] doi: 10.3109/10903127.2014.936636
23
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PREHOSPITAL EMERGENCY CARE
illustrating catastrophic injuries associated with their use have appeared in recent years,13–16 but similar injuries have also been described in the context of manual compression1,17–20 and systematic studies are needed. In this report, we describe injuries attributable to prehospital chest compressions that were documented during post-arrest hospitalization in cardiac arrest patients who survived to hospital admission. The use of mechanical compression in these cases is also detailed. Acknowledging that rare instances of lethal CPR-induced injury do occur, the objective was to characterize compression injuries detected via routine post-arrest care and understand their implications for complicating recovery after cardiac arrest.
MATERIALS AND METHODS Study Design and Setting Allina Health is a not-for-profit health system providing care to approximately 1.5 million residents in Minnesota and Wisconsin. The system uses an integrated electronic health record (EHR) across its inhospital and ambulatory care settings. It also includes an ambulance service, Allina Health Emergency Medical Services (AH-EMS), which responds to approximately 90,000 emergency calls annually and transports 60% of its patients to hospitals within the system. Two dozen other ambulance services transport patients to Allina hospitals. EMS run sheets from external prehospital agencies are scanned and uploaded into the system’s EHR. For this investigation, a retrospective cohort study was conducted among adult patients who had initially survived nontraumatic out-of-hospital cardiac arrest (OHCA) and were hospitalized between January 2009 and May 2012 at any of the 11 Allina hospitals. By 2009, AH-EMS had fully implemented use of the LUCASTM chest compression system (Physio-Control/Jolife AB, Lund, Sweden) as standard equipment and details of the protocol for device use have been previously described.21 In short, when use of the device is not contraindicated, placement is to occur as soon as possible, manual compressions are not to be delayed for the purpose of application, and pauses for application should be less than 10 seconds. Between 2010 and 2012, three other EMS providers in the area began sporadically using LUCASTM on an experimental basis.
Case Ascertainment Potential cases were identified by querying the EHR for patients with ICD-9 diagnosis codes indicative of cardiac arrest or ventricular fibrillation (i.e., 427.5 and 427.41) who had provided consent for the use of their data for research. To grossly filter out inhospital ar-
JANUARY/MARCH 2015
VOLUME 19 / NUMBER 1
rests, the qualifying code was required to be either the admitting diagnosis code or have a corresponding “present on admission” designation per CMS criteria. This initially yielded 616 potential cases, but upon preliminary chart review 376 were excluded because they did not reflect true OHCA, were the result of trauma, or did not involve prehospital chest compressions. A total of 240 cases remained for abstraction. The study was approved by the Allina institutional review board with a waiver of informed consent.
Data Collection and Measures Patient and event details were uploaded from the EHR into an online data collection tool. A single abstractor (LLB) reviewed all EMS run sheets and recorded EMS provider, bystander compressions (yes, no), duration of prehospital care (i.e., interval between EMS arrival at patient and patient arrival in ED), and use of mechanical compression (yes, no). Use of mechanical compression was defined as any use in the prehospital setting or in the ED. While patients with no mechanical compression received manual compressions exclusively, it is assumed those with mechanical compression received some manual compressions during their resuscitation (i.e., before device was placed). Precise cumulative compression time is not routinely recorded by paramedics, so all available time stamps in the prehospital record, including notations of periods of spontaneous circulation, were used to approximate and categorize total prehospital compression time as 20 minutes. Bystander compressions were not considered in the estimate of prehospital compression time, and where a reasonable estimate could not be made, compression time was categorized as unknown. Independently, two physicians (JSH, CES) each conducted a comprehensive review of the hospitalization records of half of the cases. All ED provider notes, imaging results, hospital course notes, and discharge summaries were examined for evidence of injuries that were most likely the result of chest compression. Fields in the data collection tool allowed the physicians to indicate rib fracture, sternal fracture, liver injury, splenic injury, pneumothorax, hemothorax, mediastinal hemorrhage, pericardial hemorrhage, pulmonary contusion, and thoracic artery injury, and other injuries not specified. Information about imaging and any post-EMS compressions performed in the hospital was also noted. Injuries were classified as life-threatening, consequential, or insignificant according to the following definitions used previously3 : life-threatening – reasonably expected to interfere with cardiovascular or respiratory function to the extent of depriving tissue of needed blood and oxygen, exsanguinations in excess of 800 mL; consequential – demands therapy for repair or for alleviation of pain, expected to prolong
L. L. Boland et al.
25
CHEST COMPRESSION INJURIES
hospitalization; insignificant – requires no therapy (expected to heal spontaneously) or may require limited one-time only therapy. Physician reviewers were instructed to refrain from viewing EMS run sheets, but it was impossible to ensure blinding to EMS agency and use of mechanical compression as these are sometimes mentioned in hospital provider notes.
Prehosp Emerg Care Downloaded from informahealthcare.com by Nyu Medical Center on 06/09/15 For personal use only.
Analysis Patient and event characteristics were described using means and proportions. Frequencies and proportions were used to examine the prevalence of compressionrelated injuries overall, by discharge status, and by other covariates of interest. T-tests and Pearson chisquare statistics were used to evaluate differences in means and proportions, respectively. Fisher’s exact test was used when expected cell counts in contingency tables were less than 5. Logistic regression models were used to generate crude and adjusted odds ratios (and 95% confidence intervals) of any compression injury. All analyses were conducted with Stata 12.1.22
RESULTS Five cases were excluded from analysis because mechanical compression use could not be determined
definitively. Of the 235 remaining cases, 117 survived to discharge and 118 died during hospitalization. Patients were treated and transported by 31 different EMS providers. The LUCASTM device was used in 104 patients (44%), including 94 prehospital uses by 5 different EMS agencies (80 AH-EMS uses, 14 uses by other EMS agencies). In the remaining 10 patients, LUCASTM was used only in the ED by hospital staff. No references to other mechanical compression devices were found, but one patient did receive compressions with a hand-held, nonautomated active compression–decompression device. Patients who died prior to discharge were more likely to be female and over the age of 75 than those who ultimately survived (Table 1). Those who died were also more likely to have had compressions for >20 minutes and to have received mechanical compression. Chest radiography (CXR) was conducted in all but 6 patients, and echocardiograms were conducted in 81%. Use of computed tomography (CT) and cardiac magnetic resonance (MR) imaging were less common, and uses of MR occurred only among those who survived to discharge. Use of anticoagulants on admission was more prevalent in patients who died during hospitalization, perhaps reflecting more extensive comorbidities in this group. Length of hospital stay was statistically significantly shorter in patients
TABLE 1. Patient and event characteristics, overall and by discharge status Discharge Status Variable
All (n = 235)
Dead (n = 118)
Age, y Age ≥ 75 yrs Male Body-mass Index, kg/m2 Body-mass Index Category, kg/m2 Normal (30) Body Weight, kg Bystander compressions Mechanical compressionb Duration of prehospital care, min Total Compression Time 20 minutes Imaging during hospitalization Chest X-ray CT Cardiac MRI Echocardiogram Medications on admission Anticoagulants Steroids Osteoporosis medications Length of stay, days
64 (15) 27% (64) 62% (145) 28.8 (7)
67 (14) 35% (41) 53% (62) 28.6 (8)
60 (15) 20% (23) 71% (83) 29.1 (6)
29% (68) 33% (78) 38% (88) 85.9 (23) 27% (64) 44% (104) 35 (12)
34% (40) 27% (31) 39% (46) 83.9 (25) 27% (31) 55% (65) 38 (12)
24% (28) 40% (47) 36% (42) 87.9 (21) 28% (33) 33% (39) 32 (11)
9% (22) 23% (55) 29% (69) 34% (81)
3% (3) 17% (20) 27% (32) 50% (59)
16% (19) 30% (35) 32% (37) 19% (22)
97% (229) 36% (85) 12% (29) 81% (190)
97% (114) 36% (42) 0% (0) 71% (84)
98% (115) 37% (43) 25% (29) 91% (106)
0.68 0.85 < 0.001 < 0.001
20% (47) 5% (12) 2% (4) 7 (7)
30% (35) 8% (9) 3% (3) 4 (5)
10% (12) 3% (3) 1% (1) 11 (6)
< 0.001 0.14 0.62 < 0.001
Results a re expressed as mean (SD) or percent (n) CT = computed tomography; MRI = magnetic resonance imaging a t-test (continuous variable) or Pearson χ 2 (categorical variables) for difference by discharge status b LUCASTM device used to deliver mechanical compressions
Alive (n = 117)
P-Valuea
< 0.001 0.010 0.005 0.62
0.060 0.19 0.88 0.001 < 0.001
< 0.001
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TABLE 2. Frequency of chest compression injuries, overall and by discharge status
Prehosp Emerg Care Downloaded from informahealthcare.com by Nyu Medical Center on 06/09/15 For personal use only.
Discharge Status
Patients with any injury Injuries by Type Sternal fracture Rib fracture ≥ 3 rib fractures Liver injury Spleen injury Pneumothorax/Pneumomediastinum Pulmonary contusion Pericardial effusion Hemorrhage Mediastinal Pericardial Retro-/Intraperitoneal Hemothorax Thoracic artery injury
All (n = 235)
Dead (n = 118)
Alive (n = 117)
31 (13%)
22 (19%)
9 (8%)
2 (1%) 22 (9%) 19 (8%) 1 (0.4%) 0 4 (2%) 3 (1%) 1 (0.4%)
2 (2%) 18 (15%) 17 (14%) 0 0 3 (3%) 2 (2%) 0
0 4 (3%) 2 (2%) 1 (1%) 0 1 (1%) 1 (1%) 1 (1%)
4 (2%) 0 2 (1%) 1 (0.4%) 1 (0.4%)
3 (3%) 0 1 (1%) 0 0
1 (1%) 0 1 (1%) 1 (1%) 1 (1%)
who died prior to discharge (4 days vs. 11 days, p < 0.001), largely because a majority (74%; n = 87) were placed on comfort care shortly after admission. Compression-related injuries were documented in the hospital records of 31 patients (13%; Table 2), and the prevalence was higher among those who died during hospitalization (19% vs. 8%, p = 0.013). The most commonly noted injury was rib fracture (9%), and 86% of patients with rib fracture had >3 ribs involved. Sternal fractures were noted in only 2 patients (1%) and no splenic injuries were documented. Overall, compression-related fractures were documented in 22 patients (9%; both patients with sternal fractures also had rib fractures). Nonskeletal injuries were found in 13 patients (6%), with 1 patient sustaining four unique visceral injuries. Injuries were characterized as insignificant in just over half of patients with any injury detected (16/31; 52%). Details of the 15 cases who sustained injuries that were characterized as life-threatening or consequential are presented in Table 3. Only 3 patients (1.3%) suffered life-threatening CPR-related trauma that required additional intervention or imaging during hospitalization. One patient developed mediastinal hemorrhage, hemothorax, and bleeding from branches of the left internal mammary artery that required coil embolization 1 day after arrest (patient 1). In a second patient, a precipitous drop in hemoglobin led to an abdominal/pelvic CT that revealed a retroperitoneal bleed (patient 2). Blood transfusions were required to stabilize the patient, intravenous heparin was discontinued, and recovery was somewhat complicated. In a third patient who suffered an intraperitoneal hemorrhage, acute pulmonary embolism was the suspected cause of arrest, and the patient had received massive transfusions, tPA and heparin before ultimately expiring < 24 hours after admission (patient 5). Among survivors, the mean length of stay (±SD) was slightly
longer in those with injuries (13.5 ± 5 days vs. 10.8 ± 6 days), although the difference was not statistically significant (p = 0.23). Of the covariates examined, death during hospitalization, total compression time > 10 minutes, and CT imaging during hospitalization were all positively associated with detection of injury (Table 4). In the crude analysis, a slightly higher prevalence of injury was observed in patients who had received mechanical compressions, but there was also a strong positive association between use of mechanical compression and total compression time. Mechanical compressions were delivered in 55% of patients who received compressions for >10 minutes and in only 26% of patients with shorter compression times (p < 0.001). After adjustment for total compression time in multivariable models, there was no association between use of mechanical compressions and CPR-associated injury. In a logistic regression model that included discharge status, age, gender, use of mechanical compression, compression time > 10 minutes, and CT imaging, only compression time > 10 minutes and CT imaging were positively and statistically significantly associated with detection of injury, with adjusted odds ratios of 7.86 (95% CI = 1.7–35.9) and 6.30 (95% CI = 2.6–15.5), respectively.
DISCUSSION In this cohort of patients who survived OHCA to hospital admission, the overall prevalence of compression-related injuries recognized during routine post-arrest care was 13%. Rib fractures were documented in 9% of patients, sternal fractures in 1%, and nonskeletal injuries in 6%. Previous injury estimates derived primarily from autopsy studies vary dramatically – from 13 to 97% for rib fractures and 1
L. L. Boland et al.
27
CHEST COMPRESSION INJURIES
TABLE 3. Characteristics of cardiac arrest patients with life-threatening or consequentiala compression injuries documented in the hospitalization record #
Gender
Age
Mechanical Compression
Patient Survived to Discharge 1 Male 81 No
2
Male
65
Yes
Prehosp Emerg Care Downloaded from informahealthcare.com by Nyu Medical Center on 06/09/15 For personal use only.
3 Female 67 No 4 Male 66 Yes Patient Expired Prior to Discharge 5 Female 54 Yes 6 7 8
Bystander Compression
Compression Time (min)
Length of Stay (days)
Imaging Conducted
No
11–20
13
CXR, CT, E
Yes
11–20
16
CXR, CT, E
No Yes
11–20 11–20
13 23
CXR, E CXR, CT, E
No
20+
1
CXR
Male Female Male
60 61 66
No No No
No Yes No
Unknown 11–20 11–20
2
