Real-world comparison between mechanical and manual cardiopulmonary resuscitation during the COVID-19 pandemic.

BACKGROUND: The COVID-19 pandemic has posed significant challenges to healthcare systems worldwide, including an increase in out-of-hospital cardiac arrests (OHCA). Healthcare providers are now required to use personal protective equipment (PPE) during cardiopulmonary resuscitation (CPR). Additionally, mechanical CPR devices have been introduced to reduce the number of personnel required for resuscitation. This study aimed to compare the outcomes of CPR performed with a mechanical device and the outcomes of manual CPR performed by personnel wearing PPE. METHODS: This multicenter observational study utilized data from the Korean Cardiac Arrest Research Consortium registry. The study population consisted of OHCA patients who underwent CPR in emergency departments (EDs) between March 2020 and June 2021. Patients were divided into two equal propensity score matched groups: mechanical CPR group (n = 421) and PPE-equipped manual CPR group (n = 421). Primary outcomes included survival rates and favorable neurological outcomes at discharge. Total CPR duration in the ED was also assessed. RESULTS: There were no significant between-group differences with respect to survival rate at discharge (mechanical CPR: 7.4% vs PPE-equipped manual CPR: 8.3%) or favorable neurological outcomes (3.3% vs. 3.8%, respectively). However, the mechanical CPR group had a longer duration of CPR in the ED compared to the manual CPR group. CONCLUSION: This study found no significant differences in survival rates and neurological outcomes between mechanical CPR and PPE-equipped manual CPR in the ED setting. However, a longer total CPR duration was observed in the mechanical CPR group. Further research is required to explore the impact of PPE on healthcare providers' performance and fatigue during CPR in the context of the pandemic and beyond.

Evaluation of optimal scene time interval for out-of-hospital cardiac arrest using a deep neural network.

AIM: This study aims to develop a cardiac arrest prediction model using deep learning (CAPD) algorithm and to validate the developed algorithm by evaluating the change in out-of-hospital cardiac arrest patient prognosis according to the increase in scene time interval (STI). METHODS: We conducted a retrospective cohort study using smart advanced life support trial data collected by the National Emergency Center from January 2016 to December 2019. The smart advanced life support data were randomly partitioned into derivation and validation datasets. The performance of the CAPD model using the patient's age, sex, event witness, bystander cardiopulmonary resuscitation (CPR), administration of epinephrine, initial shockable rhythm, prehospital defibrillation, provision of advanced life support, response time interval, and STI as prediction variables for prediction of a patient's prognosis was compared with conventional machine learning methods. After fixing other values of the input data, the changes in prognosis of the patient with respect to the increase in STI was observed. RESULTS: A total of 16,992 patients were included in this study. The area under the receiver operating characteristic curve values for predicting prehospital return of spontaneous circulation (ROSC) and favorable neurological outcomes were 0.828 (95% confidence interval 0.826-0.830) and 0.907 (0.914-0.910), respectively. Our algorithm significantly outperformed other artificial intelligence algorithms and conventional methods. The neurological recovery rate was predicted to decrease to 1/3 of that at the beginning of cardiopulmonary resuscitation when the STI was 28 min, and the prehospital ROSC was predicted to decrease to 1/2 of its initial level when the STI was 30 min. CONCLUSION: The CAPD exhibits potential and effectiveness in identifying patients with ROSC and favorable neurological outcomes for prehospital resuscitation.

Identification of out-of-hospital cardiac arrest clusters using unsupervised learning.

AIM: Out-of-hospital cardiac arrest (OHCA) is a leading cause of death, and research has identified limitations in analyzing the factors related to the incidence of cardiac arrest and the frequency of bystander cardiopulmonary resuscitation. This study conducts a cluster analysis of the correlation between location-related factors and the outcome of patients with OHCA using two machine learning methods: variational autoencoder (VAE) and the Dirichlet process mixture model (DPMM). METHODS: Using the prospectively collected Smart Advanced Life Support registry in South Korea between August 2015 and December 2018, a secondary retrospective data analysis was performed on patients with OHCA with a presumed cause of cardiac arrest in adults of 18 years or older. VAE and DPMM were used to create clusters to determine groups with a common nature among those with OHCA. RESULTS: Among 5876 OHCA cases, 1510 patients were enrolled in the final analysis. Decision tree-based models, which have an accuracy of 95.36%, were also used to interpret the characteristics of clusters. A total of 8 clusters that had similar spatial characteristics were identified using DPMM and VAE. Among the generated clusters, the averages of the four clusters that exhibited a high survival to discharge rate and a favorable neurological outcome were 9.6% and 6.1%, and the averages of the four clusters that exhibited a low outcome were 5.1% and 3.5% respectively. In the decision tree-based models, the most important feature that could affect the prognosis of an OHCA patient was being transferred to a higher-level emergency center. CONCLUSION: This methodology can facilitate the development of a regionalization strategy that can improve the survival rate of cardiac arrest patients in different regions.

Application of the Team Emergency Assessment Measure for Prehospital Cardiopulmonary Resuscitation.

INTRODUCTION: Communication and teamwork are critical for ensuring patient safety, particularly during prehospital cardiopulmonary resuscitation (CPR). The Team Emergency Assessment Measure (TEAM) is a tool applicable to such situations. This study aimed to validate the TEAM efficiency as a suitable tool even in prehospital CPR. METHODS: A multi-centric observational study was conducted using the data of all non-traumatic out-of-hospital cardiac arrest patients aged over 18 years who were treated using video communication-based medical direction in 2018. From the extracted data of 1494 eligible patients, 67 sample cases were randomly selected. Two experienced raters were assigned to each case. Each rater reviewed 13 or 14 videos and scored the TEAM items for each field cardiopulmonary resuscitation performance. The internal consistency, concurrent validity, and inter-rater reliability were measured. RESULTS: The TEAM showed high reliability with a Cronbach's alpha value of 0.939, with a mean interitem correlation of 0.584. The mean item-total correlation was 0.789, indicating significant associations. The mean correlation coefficient between each item and the global score range was 0.682, indicating good concurrent validity. The mean intra-class correlation coefficient was 0.804, indicating excellent agreement. DISCUSSION: The TEAM can be a valid and reliable tool to evaluate the non-technical skills of a team of paramedics performing CPR.

Effects of Smart Advanced Life Support protocol implementation including CPR coaching during out-of-hospital cardiac arrest.

PURPOSE: The aim of this study was to compare out-of-hospital cardiac arrest (OHCA) outcomes before and after implementation of Smart Advanced Life Support (SALS) protocol incorporating changes in cardiopulmonary resuscitation (CPR) assistance and coaching by physicians via real-time video calls. METHODS: A prospective before-and-after multi-regional observational study was conducted between January 2014 and December 2018. In January 2016, emergency medical service (EMS) providers adopted an integrated CPR coaching by physicians via real-time video call via SALS to treat patients with OHCA focusing on high-quality cardiopulmonary resuscitation. Propensity score matching was performed to match patients. Patients' outcomes using conventional protocol were then compared with those of patients using the SALS protocol. RESULTS: Among 26,349 OHCA cases, 2351 patients and 7261 patients were enrolled during the pre-intervention and the post-intervention periods, respectively. Multivariate analysis showed that SALS was independently associated with favorable neurological outcomes [odds ratio (OR): 2.20; 95% confidence interval (CI): 1.62-2.99]. A total of 2096 patients were propensity score-matched and the two groups were well balanced. In the matched cohort, the use of SALS protocol was still associated with increased prehospital return of spontaneous circulation (ROSC) (OR: 3.83, 95% CI: 2.80-5.26), survival to discharge (OR: 1.68; 95% CI: 1.20-2.34), and favorable neurological outcomes (OR: 1.83; 95% CI: 1.19-2.82). CONCLUSION: A multidisciplinary SALS protocol for the resuscitation of patients with OHCA was associated with increased prehospital ROSC, survival to discharge, and good neurologic outcomes compared with traditional resuscitation protocol.

Survival and Rearrest in out-of-Hospital Cardiac Arrest Patients with Prehospital Return of Spontaneous Circulation: A Prospective Multi-Regional Observational Study.

OBJECTIVE: We aimed to determine the factors associated with rearrest after prehospital return of spontaneous circulation (ROSC) and examine the factors associated with survival despite rearrest. METHODS: We conducted a prospective multi-regional observational study of out-of-hospital cardiac arrest (OHCA) patients between August 2015 and July 2016. Patients received prehospital advanced cardiovascular life support performed by emergency medical technicians (EMTs). EMTs were directly supervised by medical directors (physicians) via real-time smartphone video calls [Smart Advanced Life Support (SALS)]. The study participants were categorized into rearrest (+) and rearrest (-) groups depending on whether rearrest occurred after prehospital ROSC. After rearrest, patients were further classified as survivors or non-survivors at discharge. RESULTS: SALS was performed in 1,711 OHCA patients. Prehospital ROSC occurred in 345 patients (20.2%); of these patients, 189 (54.8%) experienced rearrest [rearrest (+) group] and 156 did not experience rearrest [rearrest (-) group]. Multivariate analysis showed that a longer interval from collapse to first prehospital ROSC was independently associated with rearrest [odds ratio (OR) 1.081; 95% confidence interval (CI) 1.050-1.114]. The presence of an initial shockable rhythm was independently associated with survival after rearrest (OR 6.920; 95% CI 2.749-17.422). As a predictor of rearrest, the interval from collapse to first prehospital ROSC (cut-off: 24 min) had a sensitivity of 77% and a specificity of 54% (AUC = 0.715 [95% CI 0.661-0.769]). CONCLUSIONS: A longer interval from collapse to first prehospital ROSC was associated with rearrest, and an initial shockable rhythm was associated with survival despite the occurrence of rearrest. Emergency medical service providers and physicians should be prepared to deal with rearrest when pulses are obtained late in the resuscitation.

Characteristics and outcomes of public bath-related out-of-hospital cardiac arrests in South Korea.

OBJECTIVE: To analyze the differences in characteristics and outcomes between public bath (PB)-related and non-PB-related out-of-hospital cardiac arrest (OHCA) patients in South Korea. METHODS: We performed a retrospective observational analysis of collected data from the Smart Advanced Cardiac Life Support (SALS) registry between September 2015 and December 2018. We included adult OHCA patients (aged >18 years) with presumed OHCA of non-traumatic etiology who were attended by dispatched emergency medical services. SALS is a field advanced life support with smartphone-based direct medical direction. The primary outcome was the survival to discharge rate measured at the time of discharge. RESULTS: Of 38,995 cardiac arrest patients enrolled in the SALS registry, 11,889 were included in the final analysis. In total, 263 OHCAs occurred in PBs. Male sex and bystander cardiopulmonary resuscitation proportions appeared to be higher among PB patients than among non-PB patients. Percentages for shockable rhythm, witnessed rate, and number of underlying disease were lower in the PB group than in the non-PB group. Prehospital return of spontaneous circulation (11.4% vs. 19.5%, P=0.001), survival to discharge (2.3% vs. 9.9%, P<0.001), and favorable neurologic outcome (1.9% vs. 5.8%, P=0.007) in PB patients were significantly poorer than those in non-PB patients. CONCLUSION: Patient characteristics and emergency medical services factors differed between PB and non-PB patients. All outcomes of PB-related OHCA were poorer than those of non-PB-related OHCA. Further treatment strategies should be developed to improve the outcomes of PB-related cardiac arrest.

Optimal combination of clinical examinations for neurologic prognostication of out-of-hospital cardiac arrest patients.

AIM: Targeted temperature management (TTM) may alter the results of clinical examination and delay motor response recovery; hence, re-establishing the accuracy and optimal timing of performing clinical examinations are crucial. Therefore, we aimed to identify the optimal combination and timing of clinical examinations for predicting the neurologic outcomes in patients undergoing TTM. METHODS: We conducted a retrospective analysis of prospectively collected multicentre registry data. All enrolled patients were supposed to undergo pupil light reflex (PLR), corneal reflex (CR), and Glasgow Coma Scale for 7 days after return of spontaneous circulation (ROSC). We investigated the timing of each examination based on the ROSC and rewarming completion times. The primary outcome was poor neurologic outcome (cerebral performance category 3,4, or 5) at 6 months after cardiac arrest. RESULTS: A total of 715 patients treated with TTM within 2 years, were enrolled. The PLR is more specific than the other examinations, and the specificity of the combination of PLR with CR was 100% 72 h after the ROSC or 24 h after rewarming completion. The sensitivity for the combination of PLR with CR 72 h after the ROSC was 55.3 (49.8-60.7) %, which was not different from that noted 24 h after rewarming completion (P = 0.65). CONCLUSION: The combination of PLR with CR showed specificity approaching 100% 72 h after the ROSC or 24 h after rewarming completion. These findings can provide a clinical reference for predicting the neurological outcomes in patients undergoing TTM, especially in institutions without up-to-date facilities.

Factors Associated with High-Quality Cardiopulmonary Resuscitation Performed by Bystander.

Bystander cardiopulmonary dresuscitation (CPR) improves the survival and neurological outcomes of sudden cardiac arrest patients. The rate of bystander CPR is increasing; however, its performance quality has not been evaluated in detail. In this study, emergency medical technicians (EMTs) in the field evaluated bystander CPR quality, and we aimed to investigate the association between bystander information and CPR quality. This retrospective cohort study was based on data included in the Smart Advanced Life Support (SALS) registry between January 2016 and December 2017. We included patients older than 18 years who experienced an out-of-hospital cardiac arrest (OHCA) due to medical causes. Bystander CPR quality was judged to be "high" when the hand positions were appropriate and when compression rates of at least 100/min and compression depths of at least 5 cm were achieved. Among 6,769 eligible patients, 3,799 (58.7%) received bystander CPR, and 6% of bystanders performed high-quality CPR. After adjustment, the occurrence of cardiac arrest at home (adjusted odds ratio (aOR), 95% confidence interval (CI); 0.42, 0.27-0.64), witnessed cardiac arrest (1.45, 1.03-2.06), and younger bystander age all showed associations with one another. High-quality CPR led to a 4.29-fold increase in the chance of neurological recovery. In particular, high-quality CPR in patients aged 60 years showed a significant association compared with other age groups (7.61, 1.41-41.04). The main factor affecting CPR quality in this study was the age of the bystander, and older bystanders found it more difficult to maintain CPR quality. To improve the quality of bystander CPR, training among older bystanders should be the focus.

Correction to: Impact of early intravenous amiodarone administration on neurological outcome in refractory ventricular fibrillation: retrospective analysis of prospectively collected prehospital data.

Following the publication of the original article [1], the authors unfortunately became aware of some typesetting and resolution problems in Figs. 1 and 2.

Impact of early intravenous amiodarone administration on neurological outcome in refractory ventricular fibrillation: retrospective analysis of prospectively collected prehospital data.

BACKGROUND: The 2015 AHA guidelines recommend that amiodarone should be used for patients with refractory ventricular fibrillation (RVF). However, the optimal time interval between the incoming call and amiodarone administration (call-to-amiodarone administration interval) in RVF patients has not been investigated. We hypothesized that the time elapsed until amiodarone administration could affect the neurological outcome at hospital discharge in patients with RVF. METHODS AND RESULTS: This study is a retrospective analysis of prospectively collected data. One hundred thirty-four patients were enrolled. In univariate logistic regression, the probability of a good neurological outcome at hospital discharge decreased as the time elapsed until amiodarone administration increased (OR 0.89 [95% CI = 0.80-0.99]). In multivariate logistic regression, the patients who were administered amiodarone in less than 20 min showed higher rates of prehospital ROSC, survival at hospital arrival, any ROSC, survival at admission, survival to discharge, and good CPC at hospital discharge. The call-to-amiodarone administration interval of ≤20 min (OR 6.92, 95% CI 1.72-27.80) was the independent factor affecting the neurological outcome at hospital discharge. CONCLUSION: Early amiodarone administration (≤ 20 min) showed better neurological outcome at hospital discharge for OHCA patients who showed initial ventricular fibrillation and subsequent RVF.

Effect of the Floor Level on the Probability of a Neurologically Favorable Discharge after Cardiac Arrest according to the Event Location.

As the number of people living in high-rise buildings increases, so does the incidence of cardiac arrest in these locations. Changes in cardiac arrest location affect the recognition of patients and emergency medical service (EMS) activation and response. This study aimed to compare the EMS response times and probability of a neurologically favorable discharge among patients who suffered an out-of-hospital cardiac arrest (OHCA) event while on a high or low floor at home or in a public place. This retrospective analysis was based on Smart Advanced Life Support registry data from January 2016 to December 2017. We included patients older than 18 years who suffered an OHCA due to medical causes. A high floor was defined as ≥3rd floor above ground. We compared the probability of a neurologically favorable discharge according to floor level and location (home vs. public place) of the OHCA event. Of the 6,335 included OHCA cases, 4,154 (65.6%) events occurred in homes. Rapid call-to-scene times were reported for high-floor events in both homes and public places. A longer call-to-patient time was observed for home events. The probability of a neurologically favorable discharge after a high-floor OHCA was significantly lower than that after a low-floor OHCA if the event occurred in a public place (adjusted odds ratio (aOR), 0.58; 95% confidence intervals (CI), 0.37-0.89) but was higher if the event occurred at home (aOR, 1.40; 95% CI, 0.96-2.03). Both the EMS response times to OHCA events in high-rise buildings and the probability of a neurologically favorable discharge differed between homes and public places. The results suggest that the prognosis of an OHCA patient is more likely to be affected by the building structure and use rather than the floor height.

Association between ambulance response time and neurologic outcome in patients with cardiac arrest.

PURPOSE: Emergency medical services (EMS) response time is one of prehospital factors associated with survival rate of patients with out-of-hospital cardiac arrest (OHCA). The objective of this study was to determine whether short EMS response time was associated with improved neurologic outcome of patients with OHCA through prospective analysis. METHODS: We performed a prospective observational analysis of collected data from KoCARC registry between October 2015 and December 2016. OHCA patients aged 18 years or older with presumed cardiac etiology by emergency physicians in emergency department were included in this study. RESULTS: Of 3187 cardiac arrest patients enrolled in the KoCARC registry, 2309 patients were included in the final analysis. Response time threshold was 11.5 min for prehospital return of spontaneous circulation and 7.5 min for survival to discharge and favorable neurologic outcome. Patients in the ≤7.5 min response time group showed increased odds of survival to discharge (OR: 1.54, 95% CI: 1.13-2.10, p = .006) and favorable neurologic recovery (OR: 2.01, 95% CI: 1.36-2.99, p = .001). When response time was decreased by 1 min, all outcomes were improved (survival to discharge, OR: 1.08; 95% CI: 1.04-1.12, p < .001; favorable neurological outcome, OR: 1.14, 95% CI: 1.07-1.21, p < .001). CONCLUSION: We found that shorter EMS response time could lead to favorable neurologic outcome in patients with OHCA of presumed cardiac origin. EMS response time threshold associated with improved favorable outcome was ≤7.5 min.

Variability of Post-Cardiac Arrest Care Practices Among Cardiac Arrest Centers: United States and South Korean Dual Network Survey of Emergency Physician Research Principal Investigators.

There is little consensus regarding many post-cardiac arrest care parameters. Variability in such practices could confound the results and generalizability of post-arrest care research. We sought to characterize the variability in post-cardiac arrest care practice in Korea and the United States. A 54-question survey was sent to investigators participating in one of two research groups in South Korea (Korean Hypothermia Network [KORHN]) and the United States (National Post-Arrest Research Consortium [NPARC]). Single investigators from each site were surveyed (N = 40). Participants answered questions based on local institutional protocols and practice. We calculated descriptive statistics for all variables. Forty surveys were completed during the study period with 30 having greater than 50% of questions completed (75% response rate; 24 KORHN and 6 NPARC). Most centers target either 33°C (N = 16) or vary the target based on patient characteristics (N = 13). Both bolus and continuous infusion dosing of sedation are employed. No single indication was unanimous for cardiac catheterization. Only six investigators reported having an institutional protocol for withdrawal of life-sustaining therapy (WLST). US patients with poor neurological prognosis tended to have WLST with subsequent expiration (N = 5), whereas Korean patients are transferred to a secondary care facility (N = 19). Both electroencephalography modality and duration vary between institutions. Serum biomarkers are commonly employed by Korean, but not US centers. We found significant variability in post-cardiac arrest care practices among US and Korean medical centers. These practice variations must be taken into account in future studies of post-arrest care.

The Anion Gap is a Predictive Clinical Marker for Death in Patients with Acute Pesticide Intoxication.

Pesticide formulation includes solvents (methanol and xylene) and antifreeze (ethylene glycol) whose metabolites are anions such as formic acid, hippuric acid, and oxalate. However, the effect of the anion gap on clinical outcome in acute pesticide intoxication requires clarification. In this prospective study, we compared the anion gap and other parameters between surviving versus deceased patients with acute pesticide intoxication. The following parameters were assessed in 1,058 patients with acute pesticide intoxication: blood chemistry (blood urea nitrogen, creatinine, glucose, lactic acid, liver enzymes, albumin, globulin, and urate), urinalysis (ketone bodies), arterial blood gas analysis, electrolytes (Na(+), K(+), Cl(-) HCO3 (-), Ca(++)), pesticide field of use, class, and ingestion amount, clinical outcome (death rate, length of hospital stay, length of intensive care unit stay, and seriousness of toxic symptoms), and the calculated anion gap. Among the 481 patients with a high anion gap, 52.2% had a blood pH in the physiologic range, 35.8% had metabolic acidosis, and 12.1% had acidemia. Age, anion gap, pesticide field of use, pesticide class, seriousness of symptoms (all P < 0.001), and time lag after ingestion (P = 0.048) were significant risk factors for death in univariate analyses. Among these, age, anion gap, and pesticide class were significant risk factors for death in a multiple logistic regression analysis (P < 0.001). In conclusions, high anion gap is a significant risk factor for death, regardless of the accompanying acid-base balance status in patients with acute pesticide intoxication.

Common Pesticides Used in Suicide Attempts Following the 2012 Paraquat Ban in Korea.

To determine the change in pesticides used during suicide attempts after the 2012 paraquat (PQ) ban, we evaluated the annual number of suicide attempts by pesticide ingestion between 2011 and 2014. We extracted demographic, clinical outcome, and pesticide class data from the medical records of 1,331 patients that attempted suicide by pesticide ingestion. Pesticides were sorted into 5 groups: herbicides, insecticides, fungicides, other pesticides, and combined pesticides. Each group was subdivided into various classes based on publications by the respective Resistance Action Committees. The chi-square test for trends was used to compare the annual incidence of categorical variables. The total number of suicide attempts decreased each year, from 399 in 2011 to 245 in 2014. Simultaneously, PQ ingestion decreased from 253 patients in 2011 to 60 in 2014. The proportion of PQ to pesticides also decreased from 63.4% in 2011 to 24.5% in 2014. Furthermore, the rate of decrease in the proportion of PQ to all herbicide categories increased by calendar year. In conclusion, there is a significant trend in increased annual number of suicides and proportion of suicides using glyphosates and glufosinates versus total herbicides. However, the number of suicide attempts using glyphosate and glufosinate is lower than that using PQ. The ratio of persons completing suicide to those attempting suicide after pesticide ingestion has decreased every year after the PQ ban.

Availability of intravenous lipid emulsion therapy on endosulfan-induced cardiovascular collapse.

Acute Endosulfan poisoning is associated with a high mortality rate in humans, and can exceed 30% [Moon JM, Chun BJ. Acute endosulfan poisoning: a retrospective study. Hum Exp Toxicol 2009;28:309-16]. Prophylactic anticonvulsant therapy for symptomatic patients and aggressive treatment for seizures may limit morbidity, but, no effective antidote is available [Moses V, Peter JV. Acute intentional toxicity: endosulfan and other organochlorines. Clin Toxicol (Phila) 2010;48:539-44]. However, endosulfan poisoning is often completely reversible with the appropriate management [Karatas AD, Aygun D, Baydin A. Characteristics of endosulfan poisoning: a study of 23 cases. Singapore Med J 2006;47:1030-2]. Intravenous lipid emulsion (ILE) may be a useful in treatment of lipophilic medication overdoses as an adjunct to antidotal therapy [Rothschild L, Berns S, Oswald S, et al. Intravenous lipid emulsion in clinical toxicology. Scand J Trauma Resusc Emerg Med 2010;18:51]. We believe that this is its first reported use in endosulfan toxicity.

Identification of reassortant pandemic H1N1 influenza virus in Korean pigs.

Since the 2009 pandemic human H1N1 influenza A virus emerged in April 2009, novel reassortant strains have been identified throughout the world. This paper describes the detection and isolation of reassortant strains associated with human pandemic influenza H1N1 and swine influenza H1N2 (SIV) viruses in swine populations in South Korea. Two influenza H1N2 reassortants were detected, and subtyped by PCR. The strains were isolated using Madin- Darby canine kidney (MDCK) cells, and genetically characterized by phylogenetic analysis for genetic diversity. They consisted of human, avian, and swine virus genes that were originated from the 2009 pandemic H1N1 virus and a neuraminidase (NA) gene from H1N2 SIV previously isolated in North America. This identification of reassortment events in swine farms raises concern that reassortant strains may continuously circulate within swine populations, calling for the further study and surveillance of pandemic H1N1 among swine.