Marc T. Zubrow, MD

Hospital‐acquired venous thrombus embolism (VTE) is a pressing patient health and safety issue and has been identified as a causal factor in preventable deaths in the hospital setting.[1, 2] More than 540,000 hospitalizations with VTE occur each year among adults in the United States.[3] The number of adults with VTE is anticipated to increase from 0.95 million in 2006 to 1.82 million in 2050.[4] The Institute of Medicine has defined failure to provide adequate thromboprophylaxis to hospitalized, at‐risk patients as a medical error.[2, 5] The American College of Chest Physicians guidelines state that thromboprophylaxis is highly effective at preventing deep vein thrombosis (DVT) and proximal DVT, highly effective at preventing symptomatic VTE and fatal pulmonary emboli (PE), and that the prevention of DVT also prevents PE.[6] Where anticoagulation is contraindicated, mechanical methods of thromboprophylaxis are recommended as preferable to no thromboprophylaxis, with careful attention directed toward ensuring the proper use of, and optimal adherence with, mechanical prophylaxis.[7, 8] In our institution, concerns about the existence of asymptomatic clots being propagated into PEs by the placement of pneumatic compression boots (PCBs), led to routine performance of duplex Doppler ultrasound with compression (DUSC) before applying PCBs to those patients who were admitted and who were deemed to have a contraindication to anticoagulation prophylaxis. The recently released (April 2012) American College of Radiology Choosing Wisely list of practices specifically recommends forgoing imaging for DVT and PE in the absence of risk factors.[9] The recommendations do not specifically address screening for DVT prior to the initiation of prophylaxis. The goal of this prospective observational study, conducted prior to the Choosing Wisely campaign, was to verify our hypothesis that the prevalence of asymptomatic DVTs was very low, and provide our clinicians with evidence to allay concerns about placement of PCBs without imaging, allowing a practice pattern that would reduce costs without impacting patient safety.

METHODS

RESULTS

A total of 1136 consecutive records were examined; 4 records were excluded from the analysis because they had a diagnosed PE prior to US, and 35 records were excluded because the US was performed beyond 48 hours after admission. The final dataset included 1097 hospital admissions for 1071 patients. Of the 1097 admissions, 759 (69.2%) originated from the emergency department (ED). It is important to note that 70,161 hospital admissions occurred during the same time period, of which 36,363 (51.8%) were admissions that started in the ED. The proportion of patients requiring mechanical DVT prophylaxis is therefore very small (<5%), assuming that a large number of the patients with unplanned admissions would require DVT prophylaxis.

Of the 1071 patients in the final analytical dataset, 544 (50.8%) were male, the mean age was 65.5 years, the mean BMI was 28.7 (median, 27.0) (Table 1), and the majority of the patients were white. US was performed within 24 hours in 712 (66.5%) patients, and 665 (62.1%) had Medicare. An asymptomatic DVT was detected by DUSC in 19 patients (1.8%). None of the clinical and demographic characteristics were statistically different between those with DVT and without (Table 1).

Patients with DVT had at least 1 risk factor; 16 (84.2%) of them had 2 or more risk factors. In addition, the presence of 2 or more risk factors was much more frequent among those with DVT than among those without (84.2% [16/19] vs 58.4% [614/1052], P=0.03).

As shown in Table 2, a history of DVT or PE and ambulatory dysfunction are the only risk factors associated with DVT at admission. In addition, the prevalence of DVT increases as the number of risk factors increases (Table 3). The prevalence is much higher in those who had 4 or more risk factors than among those with fewer than 4 risk factors (12.2% [6/49] vs 1.3% [13/1022], P=0.0001).

Results of the logistic regression, similar to those of the nonadjusted analysis, showed that the only risk factors independently associated with the discovery of a DVT upon DUSC were the presence of ambulatory dysfunction (odds ratio [OR]: 2.99, 95% confidence interval [CI]: 1.13‐7.90) and a history of DVT or PE (OR: 10.51, 95% CI: 3.90‐28.31) (Table 4).

We estimated a savings for Medicare of approximately $266,000 to $280,000 ($261.07 1071 DUSC or $261.07 1022 [after excluding the patients with 4 or more risk factors]) over 13 months had the DUSC not being conducted.

DISCUSSION

This study shows that discovering an asymptomatic DVT is relatively rare (<2%) in patients arriving at the hospital for all causes of admission, even taking into account multiple risk factors that increase the risk for DVTs. The study strongly supports the practice of placing compression devices as soon as possible for those patients who have a contraindication to anticoagulant prophylaxis. Along with reducing the delay to placement while awaiting the test, there is significant cost reduction to the healthcare system by not doing DUSC. There appears to be no need for diagnostic studies prior to the placement of these devices unless the patient has more than 3 risk factors or there is a history of previous DVT or ambulatory dysfunction. This study strongly supports the premise that patients are not arriving with DVTs, but are developing them in the hospital.[1, 2, 10] The 1.8% prevalence of asymptomatic DVT in this study is somewhat lower than that found in other studies. The Prophylaxis for Thromboembolism in Critical Care Trial (PROTECT) tested dalteparin vs unfractionated heparin on 3764 patients in the intensive care unit. Initial screening done to rule out DVT found that 3.5% of patients receiving dalteparin and 3.4% receiving unfractionated heparin had proximal DVTs.[8] Other Investigators used venous compression ultrasound examinations of the lower limbs to determine that 5.5% of patients hospitalized in a medical unit have an asymptomatic DVT of the lower limbs on admission.[5] A limitation of that study is the inclusion of all thrombo emboli, specifically those found in the calf (19 out of 21, or 90%). However, if one eliminates the calf venous thrombi, not considered risk factors for PE, the prevalence of DVT (0.85%) is about half that of our observed 1.8%.

In common with previous studies, a history of previous thromboembolic disease was clearly the most significant of many evaluated risk factors for DVT.[5, 6, 10] Ambulatory dysfunction was also a statistically significant risk factor that was likely under‐reported here because of the inexact documentation in many of the medical records. Interestingly, a history of active malignancy did not prove to be a significant risk factor, contrary to other study reports.[5, 6, 10]

The frequency of asymptomatic DVT appears to increase with the accumulation of risk factors. An asymptomatic DVT existed in 1.3% of the patients with 3 or fewer risk factors, compared with 12.2% of those with 4 or 5 risk factors. It is possible that a higher number of risk factors for DVT would be an indication for obtaining a DUSC prior to the placement of PCBs, although the small number of patients with more than 3 risk factors in our study population may limit the strength of this observation.

CONCLUSION

Our data strongly suggest, in alignment with recent recommendations, that there is no need to perform screening DUSC prior to the placement of prophylactic compression devices among hospital admissions who have contraindications to anticoagulation. Rather, efforts should be focused on implementing systems to ensure rapid placement of these compression devices at the time of admission for those patients who cannot receive anticoagulation prophylaxis. Evaluation for DVT may be of value if there is a history of previous DVT or PE, ambulatory dysfunction, or more than 3 risk factors, as the information may change the therapeutic approach. Current guidelines recommend the measurement of D‐dimers as a screening tool for DVT.[11]

Hospital‐acquired venous thrombus embolism (VTE) is a pressing patient health and safety issue and has been identified as a causal factor in preventable deaths in the hospital setting.[1, 2] More than 540,000 hospitalizations with VTE occur each year among adults in the United States.[3] The number of adults with VTE is anticipated to increase from 0.95 million in 2006 to 1.82 million in 2050.[4] The Institute of Medicine has defined failure to provide adequate thromboprophylaxis to hospitalized, at‐risk patients as a medical error.[2, 5] The American College of Chest Physicians guidelines state that thromboprophylaxis is highly effective at preventing deep vein thrombosis (DVT) and proximal DVT, highly effective at preventing symptomatic VTE and fatal pulmonary emboli (PE), and that the prevention of DVT also prevents PE.[6] Where anticoagulation is contraindicated, mechanical methods of thromboprophylaxis are recommended as preferable to no thromboprophylaxis, with careful attention directed toward ensuring the proper use of, and optimal adherence with, mechanical prophylaxis.[7, 8] In our institution, concerns about the existence of asymptomatic clots being propagated into PEs by the placement of pneumatic compression boots (PCBs), led to routine performance of duplex Doppler ultrasound with compression (DUSC) before applying PCBs to those patients who were admitted and who were deemed to have a contraindication to anticoagulation prophylaxis. The recently released (April 2012) American College of Radiology Choosing Wisely list of practices specifically recommends forgoing imaging for DVT and PE in the absence of risk factors.[9] The recommendations do not specifically address screening for DVT prior to the initiation of prophylaxis. The goal of this prospective observational study, conducted prior to the Choosing Wisely campaign, was to verify our hypothesis that the prevalence of asymptomatic DVTs was very low, and provide our clinicians with evidence to allay concerns about placement of PCBs without imaging, allowing a practice pattern that would reduce costs without impacting patient safety.

METHODS

RESULTS

A total of 1136 consecutive records were examined; 4 records were excluded from the analysis because they had a diagnosed PE prior to US, and 35 records were excluded because the US was performed beyond 48 hours after admission. The final dataset included 1097 hospital admissions for 1071 patients. Of the 1097 admissions, 759 (69.2%) originated from the emergency department (ED). It is important to note that 70,161 hospital admissions occurred during the same time period, of which 36,363 (51.8%) were admissions that started in the ED. The proportion of patients requiring mechanical DVT prophylaxis is therefore very small (<5%), assuming that a large number of the patients with unplanned admissions would require DVT prophylaxis.

Of the 1071 patients in the final analytical dataset, 544 (50.8%) were male, the mean age was 65.5 years, the mean BMI was 28.7 (median, 27.0) (Table 1), and the majority of the patients were white. US was performed within 24 hours in 712 (66.5%) patients, and 665 (62.1%) had Medicare. An asymptomatic DVT was detected by DUSC in 19 patients (1.8%). None of the clinical and demographic characteristics were statistically different between those with DVT and without (Table 1).

Patients with DVT had at least 1 risk factor; 16 (84.2%) of them had 2 or more risk factors. In addition, the presence of 2 or more risk factors was much more frequent among those with DVT than among those without (84.2% [16/19] vs 58.4% [614/1052], P=0.03).

As shown in Table 2, a history of DVT or PE and ambulatory dysfunction are the only risk factors associated with DVT at admission. In addition, the prevalence of DVT increases as the number of risk factors increases (Table 3). The prevalence is much higher in those who had 4 or more risk factors than among those with fewer than 4 risk factors (12.2% [6/49] vs 1.3% [13/1022], P=0.0001).

Results of the logistic regression, similar to those of the nonadjusted analysis, showed that the only risk factors independently associated with the discovery of a DVT upon DUSC were the presence of ambulatory dysfunction (odds ratio [OR]: 2.99, 95% confidence interval [CI]: 1.13‐7.90) and a history of DVT or PE (OR: 10.51, 95% CI: 3.90‐28.31) (Table 4).

We estimated a savings for Medicare of approximately $266,000 to $280,000 ($261.07 1071 DUSC or $261.07 1022 [after excluding the patients with 4 or more risk factors]) over 13 months had the DUSC not being conducted.

DISCUSSION

This study shows that discovering an asymptomatic DVT is relatively rare (<2%) in patients arriving at the hospital for all causes of admission, even taking into account multiple risk factors that increase the risk for DVTs. The study strongly supports the practice of placing compression devices as soon as possible for those patients who have a contraindication to anticoagulant prophylaxis. Along with reducing the delay to placement while awaiting the test, there is significant cost reduction to the healthcare system by not doing DUSC. There appears to be no need for diagnostic studies prior to the placement of these devices unless the patient has more than 3 risk factors or there is a history of previous DVT or ambulatory dysfunction. This study strongly supports the premise that patients are not arriving with DVTs, but are developing them in the hospital.[1, 2, 10] The 1.8% prevalence of asymptomatic DVT in this study is somewhat lower than that found in other studies. The Prophylaxis for Thromboembolism in Critical Care Trial (PROTECT) tested dalteparin vs unfractionated heparin on 3764 patients in the intensive care unit. Initial screening done to rule out DVT found that 3.5% of patients receiving dalteparin and 3.4% receiving unfractionated heparin had proximal DVTs.[8] Other Investigators used venous compression ultrasound examinations of the lower limbs to determine that 5.5% of patients hospitalized in a medical unit have an asymptomatic DVT of the lower limbs on admission.[5] A limitation of that study is the inclusion of all thrombo emboli, specifically those found in the calf (19 out of 21, or 90%). However, if one eliminates the calf venous thrombi, not considered risk factors for PE, the prevalence of DVT (0.85%) is about half that of our observed 1.8%.

In common with previous studies, a history of previous thromboembolic disease was clearly the most significant of many evaluated risk factors for DVT.[5, 6, 10] Ambulatory dysfunction was also a statistically significant risk factor that was likely under‐reported here because of the inexact documentation in many of the medical records. Interestingly, a history of active malignancy did not prove to be a significant risk factor, contrary to other study reports.[5, 6, 10]

The frequency of asymptomatic DVT appears to increase with the accumulation of risk factors. An asymptomatic DVT existed in 1.3% of the patients with 3 or fewer risk factors, compared with 12.2% of those with 4 or 5 risk factors. It is possible that a higher number of risk factors for DVT would be an indication for obtaining a DUSC prior to the placement of PCBs, although the small number of patients with more than 3 risk factors in our study population may limit the strength of this observation.

CONCLUSION

Our data strongly suggest, in alignment with recent recommendations, that there is no need to perform screening DUSC prior to the placement of prophylactic compression devices among hospital admissions who have contraindications to anticoagulation. Rather, efforts should be focused on implementing systems to ensure rapid placement of these compression devices at the time of admission for those patients who cannot receive anticoagulation prophylaxis. Evaluation for DVT may be of value if there is a history of previous DVT or PE, ambulatory dysfunction, or more than 3 risk factors, as the information may change the therapeutic approach. Current guidelines recommend the measurement of D‐dimers as a screening tool for DVT.[11]

Hospital‐acquired venous thrombus embolism (VTE) is a pressing patient health and safety issue and has been identified as a causal factor in preventable deaths in the hospital setting.[1, 2] More than 540,000 hospitalizations with VTE occur each year among adults in the United States.[3] The number of adults with VTE is anticipated to increase from 0.95 million in 2006 to 1.82 million in 2050.[4] The Institute of Medicine has defined failure to provide adequate thromboprophylaxis to hospitalized, at‐risk patients as a medical error.[2, 5] The American College of Chest Physicians guidelines state that thromboprophylaxis is highly effective at preventing deep vein thrombosis (DVT) and proximal DVT, highly effective at preventing symptomatic VTE and fatal pulmonary emboli (PE), and that the prevention of DVT also prevents PE.[6] Where anticoagulation is contraindicated, mechanical methods of thromboprophylaxis are recommended as preferable to no thromboprophylaxis, with careful attention directed toward ensuring the proper use of, and optimal adherence with, mechanical prophylaxis.[7, 8] In our institution, concerns about the existence of asymptomatic clots being propagated into PEs by the placement of pneumatic compression boots (PCBs), led to routine performance of duplex Doppler ultrasound with compression (DUSC) before applying PCBs to those patients who were admitted and who were deemed to have a contraindication to anticoagulation prophylaxis. The recently released (April 2012) American College of Radiology Choosing Wisely list of practices specifically recommends forgoing imaging for DVT and PE in the absence of risk factors.[9] The recommendations do not specifically address screening for DVT prior to the initiation of prophylaxis. The goal of this prospective observational study, conducted prior to the Choosing Wisely campaign, was to verify our hypothesis that the prevalence of asymptomatic DVTs was very low, and provide our clinicians with evidence to allay concerns about placement of PCBs without imaging, allowing a practice pattern that would reduce costs without impacting patient safety.

METHODS

RESULTS

A total of 1136 consecutive records were examined; 4 records were excluded from the analysis because they had a diagnosed PE prior to US, and 35 records were excluded because the US was performed beyond 48 hours after admission. The final dataset included 1097 hospital admissions for 1071 patients. Of the 1097 admissions, 759 (69.2%) originated from the emergency department (ED). It is important to note that 70,161 hospital admissions occurred during the same time period, of which 36,363 (51.8%) were admissions that started in the ED. The proportion of patients requiring mechanical DVT prophylaxis is therefore very small (<5%), assuming that a large number of the patients with unplanned admissions would require DVT prophylaxis.

Of the 1071 patients in the final analytical dataset, 544 (50.8%) were male, the mean age was 65.5 years, the mean BMI was 28.7 (median, 27.0) (Table 1), and the majority of the patients were white. US was performed within 24 hours in 712 (66.5%) patients, and 665 (62.1%) had Medicare. An asymptomatic DVT was detected by DUSC in 19 patients (1.8%). None of the clinical and demographic characteristics were statistically different between those with DVT and without (Table 1).

Patients with DVT had at least 1 risk factor; 16 (84.2%) of them had 2 or more risk factors. In addition, the presence of 2 or more risk factors was much more frequent among those with DVT than among those without (84.2% [16/19] vs 58.4% [614/1052], P=0.03).

As shown in Table 2, a history of DVT or PE and ambulatory dysfunction are the only risk factors associated with DVT at admission. In addition, the prevalence of DVT increases as the number of risk factors increases (Table 3). The prevalence is much higher in those who had 4 or more risk factors than among those with fewer than 4 risk factors (12.2% [6/49] vs 1.3% [13/1022], P=0.0001).

Results of the logistic regression, similar to those of the nonadjusted analysis, showed that the only risk factors independently associated with the discovery of a DVT upon DUSC were the presence of ambulatory dysfunction (odds ratio [OR]: 2.99, 95% confidence interval [CI]: 1.13‐7.90) and a history of DVT or PE (OR: 10.51, 95% CI: 3.90‐28.31) (Table 4).

We estimated a savings for Medicare of approximately $266,000 to $280,000 ($261.07 1071 DUSC or $261.07 1022 [after excluding the patients with 4 or more risk factors]) over 13 months had the DUSC not being conducted.

DISCUSSION

This study shows that discovering an asymptomatic DVT is relatively rare (<2%) in patients arriving at the hospital for all causes of admission, even taking into account multiple risk factors that increase the risk for DVTs. The study strongly supports the practice of placing compression devices as soon as possible for those patients who have a contraindication to anticoagulant prophylaxis. Along with reducing the delay to placement while awaiting the test, there is significant cost reduction to the healthcare system by not doing DUSC. There appears to be no need for diagnostic studies prior to the placement of these devices unless the patient has more than 3 risk factors or there is a history of previous DVT or ambulatory dysfunction. This study strongly supports the premise that patients are not arriving with DVTs, but are developing them in the hospital.[1, 2, 10] The 1.8% prevalence of asymptomatic DVT in this study is somewhat lower than that found in other studies. The Prophylaxis for Thromboembolism in Critical Care Trial (PROTECT) tested dalteparin vs unfractionated heparin on 3764 patients in the intensive care unit. Initial screening done to rule out DVT found that 3.5% of patients receiving dalteparin and 3.4% receiving unfractionated heparin had proximal DVTs.[8] Other Investigators used venous compression ultrasound examinations of the lower limbs to determine that 5.5% of patients hospitalized in a medical unit have an asymptomatic DVT of the lower limbs on admission.[5] A limitation of that study is the inclusion of all thrombo emboli, specifically those found in the calf (19 out of 21, or 90%). However, if one eliminates the calf venous thrombi, not considered risk factors for PE, the prevalence of DVT (0.85%) is about half that of our observed 1.8%.

In common with previous studies, a history of previous thromboembolic disease was clearly the most significant of many evaluated risk factors for DVT.[5, 6, 10] Ambulatory dysfunction was also a statistically significant risk factor that was likely under‐reported here because of the inexact documentation in many of the medical records. Interestingly, a history of active malignancy did not prove to be a significant risk factor, contrary to other study reports.[5, 6, 10]

The frequency of asymptomatic DVT appears to increase with the accumulation of risk factors. An asymptomatic DVT existed in 1.3% of the patients with 3 or fewer risk factors, compared with 12.2% of those with 4 or 5 risk factors. It is possible that a higher number of risk factors for DVT would be an indication for obtaining a DUSC prior to the placement of PCBs, although the small number of patients with more than 3 risk factors in our study population may limit the strength of this observation.

CONCLUSION

Our data strongly suggest, in alignment with recent recommendations, that there is no need to perform screening DUSC prior to the placement of prophylactic compression devices among hospital admissions who have contraindications to anticoagulation. Rather, efforts should be focused on implementing systems to ensure rapid placement of these compression devices at the time of admission for those patients who cannot receive anticoagulation prophylaxis. Evaluation for DVT may be of value if there is a history of previous DVT or PE, ambulatory dysfunction, or more than 3 risk factors, as the information may change the therapeutic approach. Current guidelines recommend the measurement of D‐dimers as a screening tool for DVT.[11]

In‐hospital cardiac arrest (IHCA) research often relies on the first documented cardiac rhythm (FDR) on resuscitation records at the time of cardiopulmonary resuscitation (CPR) initiation as a surrogate for arrest etiology.[1] Over 1000 hospitals report the FDR and associated cardiac arrest data to national registries annually.[2, 3] These data are subsequently used to report national IHCA epidemiology, as well as to develop and refine guidelines for in‐hospital resuscitation.[4]

Suspecting that the FDR might represent the later stage of a progressive cardiopulmonary process rather than a sudden dysrhythmia, we sought to compare the first rhythm documented on resuscitation records at the time of CPR initiation with the telemetry rhythm at the time of the code blue call. We hypothesized that the agreement between FDR and telemetry rhythm would be <80% beyond that predicted by chance (kappa<0.8).[5]

METHODS

RESULTS

During the study period, there were 135 code blue calls for urgent assistance among telemetry‐monitored non‐ICU patients. Of the 135 calls, we excluded 4 events (3%) that did not meet the definition of IHCA, 9 events (7%) with missing or uninterpretable data, and 53 events (39%) with unobtainable data due to automatic purging from the telemetry server. Therefore, 69 events in 69 different patients remained for analysis. Twelve of the 69 included arrests that occurred at Wilmington Hospital and 57 at Christiana Hospital. The characteristics of the patients are shown in Table 2.

Of the 69 arrests, we used the telemetry rhythm at minute 0 in 42 patients (61%), minute 1 in 22 patients (32%), and minute 2 in 5 patients (7%). Agreement between telemetry and FDR was 65% (kappa=0.37, 95% confidence interval: 0.17‐0.56) (Table 3). Agreement did not vary significantly by sex, race, hospital, weekday, time of day, or minute used in the analysis. Agreement was not associated with survival to hospital discharge.

Of the 69 IHCA events, the FDRs vs telemetry rhythms at the time of IHCA were: asystole 17% vs 7%, VTA 25% vs 31%, and other organized rhythms 58% vs 62%. Among the 12 events with FDR recorded as asystole, telemetry at the time of the code call was asystole in 3 (25%), VTA in 1 (8%), and other organized rhythms in 8 (67%). Among the 17 events with FDR recorded as VTA, telemetry at the time of the code call was VTA in 12 (71%) and other organized rhythms in 5 (29%). Among the 40 events with FDR recorded as other organized rhythms, telemetry at the time of the code call was asystole in 2 (5%), VTA in 8 (20%), and other organized rhythms in 30 (75%). Among the 8 patients with VTA on telemetry and other organized rhythms on the resuscitation record, the other organized rhythms were documented as PEA (n=6), sinus (n=1), and bradycardia (n=1). Of the 12 patients with VTA on telemetry and on the resuscitation record, 8 (67%) had ventricular tachycardia on telemetry. Four of the 8 (50%) who had ventricular tachycardia on telemetry had deteriorated into ventricular fibrillation by the time the FDR was recorded. Of the 4 who had ventricular fibrillation on telemetry, all had ventricular fibrillation as the FDR on the resuscitation record.

DISCUSSION

These results establish that FDRs often differ from the telemetry rhythms at the time of the code blue call. This is important because national registries such as the American Heart Association's Get with the GuidelinesResuscitation[2] database use the FDR as a surrogate for arrest etiology, and use their findings to report national IHCA outcomes as well as to develop and refine evidence‐based guidelines for in‐hospital resuscitation. Our findings suggest that using the FDR may be an oversimplification of the complex progression of cardiac rhythms that occurs in the periarrest period. Adding preceding telemetry rhythms to the data elements collected may shed additional light on etiology. Furthermore, our results demonstrate that, among adults with VTA or asystole documented upon arrival of the code blue team, other organized rhythms are often present at the time the staff recognized a life‐threatening condition and called for immediate assistance. This suggests that the VTA and asystole FDRs may represent the later stages of progressive cardiopulmonary processes. This is in contrast to out‐of‐hospital cardiac arrests typically attributed to sudden catastrophic dysrhythmias that often progress to asystole unless rapidly defibrillated.[6, 7, 8] Out‐of‐hospital and in‐hospital arrests are likely different (but overlapping) entities that might benefit from different resuscitation strategies.[9, 10] We hypothesize that, for a subset of these patients, progressive respiratory insufficiency and circulatory shockconditions classically associated more strongly with pediatric than adult IHCAmay have been directly responsible for the event.[1] If future research supports the concept that progressive respiratory insufficiency and circulatory shock are responsible for more adult IHCA than previously recognized, more robust monitoring may be indicated for a larger subset of adult patients hospitalized on general wards. This could include pulse oximetry (wave form can be a surrogate for perfusion), respiratory rate, and/or end‐tidal CO₂ monitoring. In addition, if future research confirms that there is a greater distinction between in‐hospital and out‐of‐hospital cardiac arrest etiology, the expert panels that develop resuscitation guidelines should consider including setting of resuscitation as a branch point in future algorithms.

Our study had several limitations. First, the sample size was small due to uninterpretable rhythm strips, and for 39% of the total code events, the telemetry data had already been purged from the system by the time research staff attempted to retrieve it. Although we do not believe that there was any systematic bias to the data analyzed, the possibility cannot be completely excluded. Second, we were constrained by the inability to retrospectively ascertain the presence of pulses to determine if an organized rhythm identified on telemetry tracings was PEA. Thus, we categorized rhythms into large groups. Although this limited the granularity of the rhythm groups, it was a conservative approach that likely biased toward agreement (the opposite direction of our hypothesis). Third, the lack of perfect time synchronization between the telemetry system, wall clocks in the hospital, and wrist watches that may be referenced when documenting resuscitative efforts on the resuscitation record means that the rhythms we used may have reflected physiology after interventions had already commenced. Thus, in some situations, minute 1, 2, or earlier minutes may more accurately reflect the preintervention rhythm. Highly accurate time synchronization should be a central component of future prospective work in this area.

CONCLUSIONS

The FDR had only fair agreement with the telemetry rhythm at the time of the code blue call. Among those with VTA or asystole documented on CPR initiation, telemetry often revealed other organized rhythms present at the time hospital staff recognized a life‐threatening condition. In contrast to out‐of‐hospital cardiac arrest, FDR of asystole was only rarely preceded by VTA, and FDR of VTA was often preceded by an organized rhythm.[8, 11] Future studies should examine antecedent rhythms in combination with respiratory and perfusion status to more precisely determine arrest etiology.

Disclosures

Dr. Zubrow had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. The authors report no conflicts of interest.

In‐hospital cardiac arrest (IHCA) research often relies on the first documented cardiac rhythm (FDR) on resuscitation records at the time of cardiopulmonary resuscitation (CPR) initiation as a surrogate for arrest etiology.[1] Over 1000 hospitals report the FDR and associated cardiac arrest data to national registries annually.[2, 3] These data are subsequently used to report national IHCA epidemiology, as well as to develop and refine guidelines for in‐hospital resuscitation.[4]

Suspecting that the FDR might represent the later stage of a progressive cardiopulmonary process rather than a sudden dysrhythmia, we sought to compare the first rhythm documented on resuscitation records at the time of CPR initiation with the telemetry rhythm at the time of the code blue call. We hypothesized that the agreement between FDR and telemetry rhythm would be <80% beyond that predicted by chance (kappa<0.8).[5]

METHODS

RESULTS

During the study period, there were 135 code blue calls for urgent assistance among telemetry‐monitored non‐ICU patients. Of the 135 calls, we excluded 4 events (3%) that did not meet the definition of IHCA, 9 events (7%) with missing or uninterpretable data, and 53 events (39%) with unobtainable data due to automatic purging from the telemetry server. Therefore, 69 events in 69 different patients remained for analysis. Twelve of the 69 included arrests that occurred at Wilmington Hospital and 57 at Christiana Hospital. The characteristics of the patients are shown in Table 2.

Of the 69 arrests, we used the telemetry rhythm at minute 0 in 42 patients (61%), minute 1 in 22 patients (32%), and minute 2 in 5 patients (7%). Agreement between telemetry and FDR was 65% (kappa=0.37, 95% confidence interval: 0.17‐0.56) (Table 3). Agreement did not vary significantly by sex, race, hospital, weekday, time of day, or minute used in the analysis. Agreement was not associated with survival to hospital discharge.

Of the 69 IHCA events, the FDRs vs telemetry rhythms at the time of IHCA were: asystole 17% vs 7%, VTA 25% vs 31%, and other organized rhythms 58% vs 62%. Among the 12 events with FDR recorded as asystole, telemetry at the time of the code call was asystole in 3 (25%), VTA in 1 (8%), and other organized rhythms in 8 (67%). Among the 17 events with FDR recorded as VTA, telemetry at the time of the code call was VTA in 12 (71%) and other organized rhythms in 5 (29%). Among the 40 events with FDR recorded as other organized rhythms, telemetry at the time of the code call was asystole in 2 (5%), VTA in 8 (20%), and other organized rhythms in 30 (75%). Among the 8 patients with VTA on telemetry and other organized rhythms on the resuscitation record, the other organized rhythms were documented as PEA (n=6), sinus (n=1), and bradycardia (n=1). Of the 12 patients with VTA on telemetry and on the resuscitation record, 8 (67%) had ventricular tachycardia on telemetry. Four of the 8 (50%) who had ventricular tachycardia on telemetry had deteriorated into ventricular fibrillation by the time the FDR was recorded. Of the 4 who had ventricular fibrillation on telemetry, all had ventricular fibrillation as the FDR on the resuscitation record.

DISCUSSION

These results establish that FDRs often differ from the telemetry rhythms at the time of the code blue call. This is important because national registries such as the American Heart Association's Get with the GuidelinesResuscitation[2] database use the FDR as a surrogate for arrest etiology, and use their findings to report national IHCA outcomes as well as to develop and refine evidence‐based guidelines for in‐hospital resuscitation. Our findings suggest that using the FDR may be an oversimplification of the complex progression of cardiac rhythms that occurs in the periarrest period. Adding preceding telemetry rhythms to the data elements collected may shed additional light on etiology. Furthermore, our results demonstrate that, among adults with VTA or asystole documented upon arrival of the code blue team, other organized rhythms are often present at the time the staff recognized a life‐threatening condition and called for immediate assistance. This suggests that the VTA and asystole FDRs may represent the later stages of progressive cardiopulmonary processes. This is in contrast to out‐of‐hospital cardiac arrests typically attributed to sudden catastrophic dysrhythmias that often progress to asystole unless rapidly defibrillated.[6, 7, 8] Out‐of‐hospital and in‐hospital arrests are likely different (but overlapping) entities that might benefit from different resuscitation strategies.[9, 10] We hypothesize that, for a subset of these patients, progressive respiratory insufficiency and circulatory shockconditions classically associated more strongly with pediatric than adult IHCAmay have been directly responsible for the event.[1] If future research supports the concept that progressive respiratory insufficiency and circulatory shock are responsible for more adult IHCA than previously recognized, more robust monitoring may be indicated for a larger subset of adult patients hospitalized on general wards. This could include pulse oximetry (wave form can be a surrogate for perfusion), respiratory rate, and/or end‐tidal CO₂ monitoring. In addition, if future research confirms that there is a greater distinction between in‐hospital and out‐of‐hospital cardiac arrest etiology, the expert panels that develop resuscitation guidelines should consider including setting of resuscitation as a branch point in future algorithms.

Our study had several limitations. First, the sample size was small due to uninterpretable rhythm strips, and for 39% of the total code events, the telemetry data had already been purged from the system by the time research staff attempted to retrieve it. Although we do not believe that there was any systematic bias to the data analyzed, the possibility cannot be completely excluded. Second, we were constrained by the inability to retrospectively ascertain the presence of pulses to determine if an organized rhythm identified on telemetry tracings was PEA. Thus, we categorized rhythms into large groups. Although this limited the granularity of the rhythm groups, it was a conservative approach that likely biased toward agreement (the opposite direction of our hypothesis). Third, the lack of perfect time synchronization between the telemetry system, wall clocks in the hospital, and wrist watches that may be referenced when documenting resuscitative efforts on the resuscitation record means that the rhythms we used may have reflected physiology after interventions had already commenced. Thus, in some situations, minute 1, 2, or earlier minutes may more accurately reflect the preintervention rhythm. Highly accurate time synchronization should be a central component of future prospective work in this area.

CONCLUSIONS

The FDR had only fair agreement with the telemetry rhythm at the time of the code blue call. Among those with VTA or asystole documented on CPR initiation, telemetry often revealed other organized rhythms present at the time hospital staff recognized a life‐threatening condition. In contrast to out‐of‐hospital cardiac arrest, FDR of asystole was only rarely preceded by VTA, and FDR of VTA was often preceded by an organized rhythm.[8, 11] Future studies should examine antecedent rhythms in combination with respiratory and perfusion status to more precisely determine arrest etiology.

Disclosures

Dr. Zubrow had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. The authors report no conflicts of interest.

In‐hospital cardiac arrest (IHCA) research often relies on the first documented cardiac rhythm (FDR) on resuscitation records at the time of cardiopulmonary resuscitation (CPR) initiation as a surrogate for arrest etiology.[1] Over 1000 hospitals report the FDR and associated cardiac arrest data to national registries annually.[2, 3] These data are subsequently used to report national IHCA epidemiology, as well as to develop and refine guidelines for in‐hospital resuscitation.[4]

Suspecting that the FDR might represent the later stage of a progressive cardiopulmonary process rather than a sudden dysrhythmia, we sought to compare the first rhythm documented on resuscitation records at the time of CPR initiation with the telemetry rhythm at the time of the code blue call. We hypothesized that the agreement between FDR and telemetry rhythm would be <80% beyond that predicted by chance (kappa<0.8).[5]

METHODS

RESULTS

During the study period, there were 135 code blue calls for urgent assistance among telemetry‐monitored non‐ICU patients. Of the 135 calls, we excluded 4 events (3%) that did not meet the definition of IHCA, 9 events (7%) with missing or uninterpretable data, and 53 events (39%) with unobtainable data due to automatic purging from the telemetry server. Therefore, 69 events in 69 different patients remained for analysis. Twelve of the 69 included arrests that occurred at Wilmington Hospital and 57 at Christiana Hospital. The characteristics of the patients are shown in Table 2.

Of the 69 arrests, we used the telemetry rhythm at minute 0 in 42 patients (61%), minute 1 in 22 patients (32%), and minute 2 in 5 patients (7%). Agreement between telemetry and FDR was 65% (kappa=0.37, 95% confidence interval: 0.17‐0.56) (Table 3). Agreement did not vary significantly by sex, race, hospital, weekday, time of day, or minute used in the analysis. Agreement was not associated with survival to hospital discharge.

Of the 69 IHCA events, the FDRs vs telemetry rhythms at the time of IHCA were: asystole 17% vs 7%, VTA 25% vs 31%, and other organized rhythms 58% vs 62%. Among the 12 events with FDR recorded as asystole, telemetry at the time of the code call was asystole in 3 (25%), VTA in 1 (8%), and other organized rhythms in 8 (67%). Among the 17 events with FDR recorded as VTA, telemetry at the time of the code call was VTA in 12 (71%) and other organized rhythms in 5 (29%). Among the 40 events with FDR recorded as other organized rhythms, telemetry at the time of the code call was asystole in 2 (5%), VTA in 8 (20%), and other organized rhythms in 30 (75%). Among the 8 patients with VTA on telemetry and other organized rhythms on the resuscitation record, the other organized rhythms were documented as PEA (n=6), sinus (n=1), and bradycardia (n=1). Of the 12 patients with VTA on telemetry and on the resuscitation record, 8 (67%) had ventricular tachycardia on telemetry. Four of the 8 (50%) who had ventricular tachycardia on telemetry had deteriorated into ventricular fibrillation by the time the FDR was recorded. Of the 4 who had ventricular fibrillation on telemetry, all had ventricular fibrillation as the FDR on the resuscitation record.

DISCUSSION

These results establish that FDRs often differ from the telemetry rhythms at the time of the code blue call. This is important because national registries such as the American Heart Association's Get with the GuidelinesResuscitation[2] database use the FDR as a surrogate for arrest etiology, and use their findings to report national IHCA outcomes as well as to develop and refine evidence‐based guidelines for in‐hospital resuscitation. Our findings suggest that using the FDR may be an oversimplification of the complex progression of cardiac rhythms that occurs in the periarrest period. Adding preceding telemetry rhythms to the data elements collected may shed additional light on etiology. Furthermore, our results demonstrate that, among adults with VTA or asystole documented upon arrival of the code blue team, other organized rhythms are often present at the time the staff recognized a life‐threatening condition and called for immediate assistance. This suggests that the VTA and asystole FDRs may represent the later stages of progressive cardiopulmonary processes. This is in contrast to out‐of‐hospital cardiac arrests typically attributed to sudden catastrophic dysrhythmias that often progress to asystole unless rapidly defibrillated.[6, 7, 8] Out‐of‐hospital and in‐hospital arrests are likely different (but overlapping) entities that might benefit from different resuscitation strategies.[9, 10] We hypothesize that, for a subset of these patients, progressive respiratory insufficiency and circulatory shockconditions classically associated more strongly with pediatric than adult IHCAmay have been directly responsible for the event.[1] If future research supports the concept that progressive respiratory insufficiency and circulatory shock are responsible for more adult IHCA than previously recognized, more robust monitoring may be indicated for a larger subset of adult patients hospitalized on general wards. This could include pulse oximetry (wave form can be a surrogate for perfusion), respiratory rate, and/or end‐tidal CO₂ monitoring. In addition, if future research confirms that there is a greater distinction between in‐hospital and out‐of‐hospital cardiac arrest etiology, the expert panels that develop resuscitation guidelines should consider including setting of resuscitation as a branch point in future algorithms.

Our study had several limitations. First, the sample size was small due to uninterpretable rhythm strips, and for 39% of the total code events, the telemetry data had already been purged from the system by the time research staff attempted to retrieve it. Although we do not believe that there was any systematic bias to the data analyzed, the possibility cannot be completely excluded. Second, we were constrained by the inability to retrospectively ascertain the presence of pulses to determine if an organized rhythm identified on telemetry tracings was PEA. Thus, we categorized rhythms into large groups. Although this limited the granularity of the rhythm groups, it was a conservative approach that likely biased toward agreement (the opposite direction of our hypothesis). Third, the lack of perfect time synchronization between the telemetry system, wall clocks in the hospital, and wrist watches that may be referenced when documenting resuscitative efforts on the resuscitation record means that the rhythms we used may have reflected physiology after interventions had already commenced. Thus, in some situations, minute 1, 2, or earlier minutes may more accurately reflect the preintervention rhythm. Highly accurate time synchronization should be a central component of future prospective work in this area.

CONCLUSIONS

The FDR had only fair agreement with the telemetry rhythm at the time of the code blue call. Among those with VTA or asystole documented on CPR initiation, telemetry often revealed other organized rhythms present at the time hospital staff recognized a life‐threatening condition. In contrast to out‐of‐hospital cardiac arrest, FDR of asystole was only rarely preceded by VTA, and FDR of VTA was often preceded by an organized rhythm.[8, 11] Future studies should examine antecedent rhythms in combination with respiratory and perfusion status to more precisely determine arrest etiology.

Disclosures

Dr. Zubrow had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. The authors report no conflicts of interest.