Hospital Admission Survival Research Articles

Abstract Mo035: Double (Dual) Sequential Defibrillation Versus Standard Defibrillation for Refractory Ventricular Fibrillation: A Systematic Review and Meta-Analysis

Background: Refractory ventricular fibrillation (RVF) is VF that persists despite 3 or more single defibrillation attempts. Double sequential defibrillation (DSD) is a proposed defibrillation strategy for RVF that employs delivering 2 rapid sequential, transthoracic electric shocks from 2 separate defibrillators. This meta-analysis aims to identify evidence in the literature surrounding the use of DSD and compare its efficacy with standard defibrillation (SD) in patients with RVF. Methods: We conducted our meta-analysis in compliance with the PRISMA guidelines. PubMed, Embase, and Cochrane databases were used to retrieve articles. We included studies that evaluated and compared the utility of DSD versus SD in cardiac arrest adult patients who received 3 or more standard defibrillatory shocks for RVF. Our predefined outcomes of interest were VF termination (VFT), return of spontaneous circulation (ROSC), survival to hospital admission (SHA), and survival to hospital discharge (SHD). Odds ratio (OR) and 95% confidence intervals (CIs) were calculated using the random-effects model. Heterogeneity was assessed by I 2 statistic. Results: A total of 8 studies (2 randomized controlled trials and 6 observational studies) involving 1,579 patients were included in the meta-analysis. No statistically significant difference existed between DSD and SD in terms of VFT (OR, 1.58; 95% CI, 0.84-2.99; p= 0.15; I 2 =0.54), ROSC (OR, 0.91; 95% CI, 0.53-1.55; p= 0.72; I 2 =0.76), SHA (OR, 1.18; 95% CI, 0.54-2.55; p= 0.68; I 2 =0.79), and SHD (OR, 1.03; 95% CI, 0.49-2.17; p= 0.94; I 2 =0.69). Substantial heterogeneity was noticed across the analysed studies. Conclusion: Despite the growing use of DSD for the management of RVF, there remains insufficient evidence to support its widespread implementation. This meta-analysis demonstrated that DSD had no statistically significant advantage over SD. However , due to limited data in the literature further clinical trials with large sample sizes are warranted to assess the efficacy and clinical impact of DSD, and whether it can potentially be integrated into resuscitation protocols.

Is point-of-care ultrasound a reliable predictor of outcome during traumatic cardiac arrest? A systematic review and meta-analysis from the SHoC investigators

AimPoint-of-care ultrasound (POCUS) has been shown to assist in predicting outcomes in cardiac arrest. We evaluated the test characteristics of POCUS in predicting poor outcomes: failure of return of spontaneous circulation (ROSC), survival to hospital admission (SHA), survival to hospital discharge (SHD) and neurologically intact survival to hospital discharge (NISHD) in adult and paediatric patients with blunt and penetrating traumatic cardiac arrest (TCA) in out-of-hospital or emergency department settings. MethodsWe conducted a systematic review and meta-analysis using the PRISMA guidelines. We searched Clinicaltrials.gov, CINAHL, Cochrane library, EMBASE, Medline and the World Health Organization-International Clinical Trials Registry from 1974 to November 9, 2020. Risk of bias was assessed using QUADAS-2 tool. We used a random-effects meta-analysis model with 95% confidence intervals with I2 statistics for heterogeneity. ResultsWe included 8 studies involving 710 cases of TCA. For all blunt and penetrating TCA patients who failed to achieve ROSC, the specificity (proportion of patients with cardiac activity on POCUS who achieved ROSC) was 98% (95% CI 0.13 to 1.0). The sensitivity (proportion of patients with cardiac standstill on POCUS who failed to achieve ROSC) was 91% (95% CI 0.67 to 0.98). No patient with cardiac standstill survived. Substantial level of heterogeneity was noted. ConclusionsPatients in TCA without cardiac activity on POCUS have a high likelihood of death and negligible chance of SHD. The numbers of patients included in published studies remains too low for practice recommendations for termination of resuscitation based solely upon the absence of cardiac activity on POCUS.

LO42: Is point-of-care ultrasound a reliable predictor of outcome during atraumatic, non-shockable cardiac arrest? A systematic review and meta-analysis

Introduction: Point-of-Care Ultrasound (PoCUS) is being increasingly utilized during cardiac arrests for prognosis. Following the publication of recent studies, the goal of this study was to systematically review and analyze the literature to evaluate the accuracy of PoCUS in predicting return of spontaneous circulation (ROSC), survival to hospital admission (SHA), and survival to hospital discharge (SHD) in adult patients with non-traumatic, non- shockable out- of-hospital or emergency department cardiac arrest. Methods: A systematic review and meta-analysis was completed. A search of Medline, EMBASE, Cochrane, CINAHL, ClinicalTrials.gov and the World Health Organization Registry was completed from 1974 until August 24th 2018. Adult randomized controlled trials and observational studies were included. The QUADAS-2 tool was applied by two independent reviewers. Data analysis was completed according to PRISMA guidelines and with a random effects model for the meta-analysis. Heterogeneity was assessed using I-squared statistics. Results: Ten studies (1,485 participants) were included. Cardiac activity on PoCUS had a pooled sensitivity of 59.9% (95% confidence interval 36.5%-79.4%) and specificity of 91.5% (80.8%-96.5%) for ROSC; 74.7% (58.3%-86.2%) and 80.5% (71.7%-87.4%) for SHA; and 69.4% (45.5%-86.0%) and 74.6% (59.8%-85.3%) for SHD. The sensitivity of cardiac activity on PoCUS for predicting ROSC was 24.7%(6.8%-59.4%) in the asystole subgroup compared with 77% (59.4%-88.5%) within the PEA subgroup. Cardiac activity on PoCUS, compared to an absence had an odd ratio of 15.9 (5.9-42.5) for ROSC, 9.8 (4.9-19.4) for SHA and 5.7 (2.1-15.6) for SHD. Positive likelihood ratio (LR) was 6.65 (3.16-14.0) and negative LR was 0.27 (0.12-0.61) for ROSC. Conclusion: Cardiac activity on PoCUS was associated with improved odds for ROSC, SHA, and SHD among adults with non-traumatic asystole and PEA. We report lower sensitivity and higher negative likelihood ratio, but with greater heterogeneity compared to previous systematic reviews. PoCUS may provide valuable information in the management of non-traumatic PEA or asystole, but should not be viewed as the sole predictor in determining outcomes in these patients.

Does Point-of-care Ultrasound Use Impact Resuscitation Length, Rates of Intervention, and Clinical Outcomes During Cardiac Arrest? A Study from the Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHoC-ED) Investigators.

IntroductionThis third study in the Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHoC-ED) series examined potential relationships between point-of-care ultrasound (PoCUS) use and the length of resuscitation, the frequency of interventions, and clinical outcomes during cardiac arrest.MethodsA health records review was completed for adult patients (>19 years, without a do not resuscitate (DNR) order) who presented to a tertiary emergency department in cardiac arrest between 2010 and 2014. Patients were grouped based on PoCUS use and findings for cardiac activity. Data were analyzed for length of resuscitation, frequency of interventions, return of spontaneous circulation (ROSC), survival to hospital admission (SHA), and survival to hospital discharge (SHD).ResultsOf the 223 patients who met inclusion criteria, 180 (80.7%) received assessment by PoCUS during cardiac arrest management in the emergency department (ED). In the PoCUS group, 21 (11.6%) demonstrated cardiac activity and 159 (88.4%) did not. Patients with activity on PoCUS had longer mean resuscitation times (27.3; 95% confidence interval 17.7-37.0 min) than patients with no activity (11.51; 10.2-12.8 min) and patients who did not receive a PoCUS exam (14.36; 9.89-18.8 min). Patients with cardiac activity on PoCUS were more likely to receive endotracheal intubation (ET; 95.23%; 86.13-104.35%) and epinephrine (Epi; 100%; 100-100%) than patients with no activity (ET: 46.54%; 38.8-54.3%; Epi: 82.39%; 76.50-88.31%) and those with no PoCUS (ET: 65.11%; 50.87-79.36%; Epi: 81.39%; 69.76-93.03%). Those with no cardiac activity on PoCUS were much less likely to achieve ROSC (19.5%; 13.4-25.6), SHA (6.9%; 2.97-10.86%) and SHD (0.6%; -0.5-1.8%) compared to those with cardiac activity on PoCUS (ROSC; 76.19%; 57.97-94.4%), SHA (33.3%; 13.2-53.5%), SHD (9.5%; -3-22.07%), and those with no PoCUS (ROSC 39.5%; 24.9-54.1%; SHA 27.9%; 14.5- 41.3%, and SHD 6.9%; -0.6-14.59).ConclusionsEmergency department cardiac arrest patients with cardiac activity on PoCUS received longer resuscitation with higher rates of intervention as compared to those with negative findings or when no PoCUS was performed. Patients with cardiac activity on PoCUS had improved clinical outcomes as compared with patients not receiving PoCUS, and patients with no activity on PoCUS.

P003: Which factors predict resuscitation outcomes in patients arriving to the emergency department in cardiac arrest? A SHoC series study

Introduction: The decision as to whether to end resuscitation for pre-hospital cardiac arrest (CA) patients in the field or in the emergency department (ED) is commonly made based upon standard criteria. We studied the reliability of several easily determined criteria as predictors of resuscitation outcomes in a population of adults in CA transported to the ED. Methods: A retrospective database and chart analysis was completed for patients arriving to a tertiary ED in cardiac arrest, between 2010 and 2014. Patients were excluded if aged under 19. Multiple data were abstracted from charts using a standardized form. Regression analysis was used to compare criteria that predicted return of spontaneous circulation (ROSC) and survival to hospital admission (SHA). Results: 264 patients met the study inclusion criteria. Logistic regression was used to identify predictors of ROSC and SHA. The criteria that emerged as significant predictors for ROSC included; longer ED resuscitation time (Odds ratio 1.11 (1.06- 1.18)), witnessed arrest (Odds ratio 9.43 (2.58- 53.0)) and having an initial cardiac rhythm of Pulseless Electrical Activity (Odds Ratio 3.23 (1.07-9.811)) over Asystole. Receiving point of care ultrasound (PoCUS; Odds ratio 0.22 (0.07-0.69)); and having an initial cardiac rhythm of Pulseless Electrical Activity (Odds Ratio 4.10 (1.43-11.88)) were the significant predictors for SHA. Longer times for ED resuscitation was close to reaching significance for predicting SHA Conclusion: Our results suggest that both fixed and adaptable factors, including increasing resuscitation time, and PoCUS use in the ED were important independent predictors of successful resuscitation. Several commonly used criteria were unreliable predictors.

LO040: Do combined electrocardiogram rhythm and point of care ultrasound findings predict outcome during cardiac arrest? The second Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHOC-ED 2) Study

Introduction: Survival to hospital discharge is better for PEA than asystole in out-of-hospital cardiac arrest. Point of care ultrasound (PoCUS) is widely used in cardiac arrest, although not mandated by ACLS guidelines. This study examines if initial PoCUS findings combined with cardiac rhythm are predictive of outcomes including return of spontaneous circulation (ROSC), survival to hospital admission (SHA), and hospital discharge (SHD). Methods: A database review was completed for patients arriving to a tertiary ED in asystole or PEA arrest from 2010 to 2014. Patients under 19y or with a previous DNR were excluded. Patients were grouped into those with cardiac activity on PoCUS and PEA on ECG (Positive group); those with no cardiac activity recorded on PoCUS and asystole on ECG (Negative group); and those with a mix of positive and negative findings (Indeterminate group). Data was analyzed for the frequency of ROSC, SHA, and SHD. Results: 186 patients met the study criteria, with 14 (8%) in the positive group, 134 (72%) in the negative group, and 38 (20%) in the indeterminate group. The positive group had significantly better initial outcomes than the negative group: ROSC: 78% (95% CI 49-95%) vs 17% (11-25%); OR 17.70 (4.57-168.5; p < 0.0001) and SHA: 29% (8-58%) vs 7% (3-12%); OR 5.56 (1.45-21.28; p = 0.022), and then the combined negative and indeterminate groups: ROSC: 22% (16-29%), OR 12.93 (3.43-48.73; p < 0.0001; SHA: 8% (5-13%); OR 4.51 (1.25-16.27; p = 0.033). There was no difference between the positive group and either the negative or combined groups for final outcome of SHD: 0% (0-23%) vs 1% (0-5%); OR 1.83 (0.08-39.97; p = 1.00; and vs 1% (0-5%); OR 1.67 (0.08-33.96; p = 1.00). The negative group had worse initial outcomes than the combined positive and indeterminate groups: ROSC 17% (11-25%) vs. 50% (36-64%) OR 0.21 (0.10-0.42; p < 0.0001); SHA 6% (3-12%) vs. 8% (5-13%) OR 0.34 (0.13-0.92; p = 0.0490). There was no difference in SHD: 1% (0-5%) vs. 1% (0-5%) OR 0.77 (0.07-8.71; p = 1.00). Conclusion: Our results suggest that although finding positive cardiac activity on ECG (PEA) and also on PoCUS is associated with greater ROSC and SHA, it does not identify patients with a final outcome of SHD.

MP012: Is there an association between the use of cardiac ultrasound and survival outcomes in patients arriving to the emergency department in cardiac arrest? The second Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHOC-ED 2) Study

Introduction: The use of cardiac point of care ultrasound (PoCUS) to assess cardiac arrest patients is widespread, although not mandated by advanced cardiac life support (ACLS) guidelines. This study aims to examine if the use of ultrasound, along with the findings on ultrasound are associated with a difference in outcomes of cardiac arrest patients in the emergency department (ED). Methods: A retrospective database and chart analysis was completed for patients arriving to a tertiary ED in asystole or PEA cardiac arrest, between 2010 and 2014. Patients were excluded if aged under 19, or with a previous DNR order. Patients were grouped based on whether PoCUS was used during ACLS (PoCUS group) and those without PoCUS (control group). Multiple data were abstracted from charts using a standardized form. Data was analyzed for the return of spontaneous circulation (ROSC), survival to hospital admission (SHA), and survival to hospital discharge (SHD), as well as initial cardiac activity findings on PoCUS. Results: 230 patients met the study inclusion criteria, with 44 (19%) in the control group, and 186 (81%) in the PoCUS group. In the PoCUS group 20 (11%) had cardiac activity (Positive PoCUS) and 166 (89%) had no cardiac activity recorded. The control group had a higher rate of SHA than the PoCUS group (27%; 95% CI 15-43% vs. 10%: 6-15%, p = 0.0046), however there was no difference in frequency of ROSC (control: 37%; 24-55% vs. PoCUS 26%; 20-33%, p = 0.1373) or SHD (control: 7%, 95% CI 1-19%; PoCUS: 2%, 95% CI 0-5%, p = 0.0858). Positive PoCUS patients had a higher frequency of ROSC (75%; 50-91% vs. 20%; 15-27%, p < 0.001) and SHA (25%; 9-49% vs. 8%; 4-13%, p = 0.0294) than patients with no PoCUS cardiac activity, however there was no difference in the rate of SHD between the positive PoCUS patients (0%; 0-17%) and patients with no PoCUS cardiac activity (2%; 0-5%, p = 1.0000). Conclusion: Our results suggest that there is no difference in survival between cardiac arrest patients receiving PoCUS and those who do not. Although finding positive cardiac activity on PoCUS is associated with greater ROSC and survival to hospital admission, it does not identify patients with a final outcome of survival to hospital discharge.

Role of Sodium Bicarbonate in Resuscitation of out-of-Hospital Cardiac Arrest

Objective To report the use of sodium bicarbonate (SB) in out-of-hospital cardiac arrest (OHCA) and to explore the role of sodium bicarbonate in resuscitation of OHCA in terms of restoration of spontaneous circulation (ROSC) and survival, and existence of dose-dependent relationship, especially in those with prolonged arrest. Design Retrospective cohort study. Setting Emergency department of two regional hospitals in a cluster of Hong Kong. Methods Adult patients aged at least 18 years old who presented to the study centres with non-traumatic OHCA in the period between March 2013 and December 2013 were included. Cases in which resuscitations were considered medically futile or not actually performed were excluded. Those with do-not-resuscitate (DNR) order or advance directives, those who were death before arrival with postmortem changes, and those who developed ROSC before or within 15 minutes of arrival were excluded from the study. Patients with known poisoning from tricyclic antidepressant or other sodium channel blockers were excluded from analysis if any. The primary outcome of this study was ROSC. Other outcome variables included survival to hospital admission (STA) and survival to hospital discharge (STD). Results A total of 489 patients were included during the study period for analysis. We found that patients who received sodium bicarbonate injection (SB group) during CPR had a higher percentage of ROSC than those who did not (no-SB group) (60.8% vs 22.5%; p<0.001). The survival-to-admission rate was higher in the SB group (56.8%) compared with the contrary (21.4%). The difference of survival-to-discharge between the two groups did not reach statistical significance (4.1% in SB group and 2.9% in the no-SB group; p=0.484). The rate of ROSC was found to be dose dependent, being higher in higher dose of SB administration. The ROSC rate increased from no-SB (22.4%) to 57.1% if given 50 ml SB, and further to 64.1% if given ≥100 ml SB. Conclusions Our study shows that the use of sodium bicarbonate in the CPR of OHCA is beneficial in ROSC. The effect is dose dependent, with better results in higher dose (>100 ml) of sodium bicarbonate; however, we fail to demonstrate its benefit for prolonged CPR cases (>30 minutes). (Hong Kong j.emerg. med. 2015;22:281-290)

Resuscitation with Automated External Defibrillators (AED) in Uruguay

Background: Uruguayan population is 3,200,000. Survival to hospital admission (SHA) of Out of Hospital Cardiac Arrest (OHCA) case series reported by Pre Hospital Emergency Medical System (PHMS) was 21–22.5%. The 18,360 Public Access Defibrillation Law was enacted in September 2008. It requires places with large numbers of people to install AED, and all organizations nationwide to train 50% of its staff in Cardiopulmonary Resuscitation (CPR). Today there are 1572 AED installed across the country (80% were installed in the last 4 years).

Comparison of Clinical Prediction Rules for Termination of Resuscitation of Out-of-Hospital Cardiac Arrests on Arrival to Emergency Department

Objective To compare the discriminative capacities of various termination of resuscitation (TOR) rules in the prediction of futile resuscitation in the emergency department (ED). Design Prospective cohort study. Setting 2 public hospitals in a cluster in Hong Kong. Methods The data were obtained from a Cardiac Arrest Registry of the EDs of two hospitals, including consecutive adult patients suffering from non-traumatic out-of-hospital cardiac arrest from 1st August 2010 to 30th June 2012. Those with return of spontaneous circulation before ED arrival and cases without resuscitation in the EDs were excluded. The modified basic life support (BLS), modified advanced life support (ALS) and neurologic TOR rules were applied to the cohort. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value were calculated. The outcome measures were survival to hospital admission (STA) and survival to discharge (STD). Results Totally 1125 cases were included. The mean age was 72.4. Return of spontaneous circulation and STA occurred in 302 patients and 9 had STD. Regarding the outcome of STD, the modified ALS and neurologic TOR rules had outperformed the modified BLS rule. The specificity and PPV were 100% for both rules in predicting death when the rules suggested TOR. Regarding the outcome of STA, the neurologic TOR rule had the highest specificity [84.4%; 95% confident interval (CI): 79.7-88.2%] and PPV (84.5%; 95% CI: 79.8-88.3%). Conclusions The modified ALS and neurologic TOR rules have similar discriminative capacities to predict STD. The neurologic TOR rule has the highest ability to predict STA in the ED. (Hong Kong j.emerg.med. 2013;20:343-351)

Abstract P119: Erythrocyte n-3 and n-6 Polyunsaturated and Trans Fatty Acids and Survival of Sudden Cardiac Arrest

Lower levels of erythrocyte n-3 polyunsaturated fatty acid (PUFA) and higher levels of trans-fatty acid are associated with incident cardiac arrest (SCA) risk. However, it is not known whether these fatty acids also influence post-arrest survival. In addition, n-3 and n-6 PUFA play key roles in brain function and may be involved in brain resuscitation. We investigated the association of n-3, n-6 and trans-fatty acid levels with resuscitation outcomes in a population-based study of SCA. Subjects (mean age 68, 82% male) were out-of-hospital SCA patients found in ventricular fibrillation and attended by paramedics in King County, Washington, with available fatty acid measurements (n=492). Using logistic regression, we examined association between fatty acid levels and surviving to hospital admission (a proxy for heart resuscitation), and also to surviving to hospital discharge (a proxy for brain resuscitation). Both analyses adjusted for age; sex; race; year of cardiac arrest; time to arrival of emergency medical services; whether the event was witnessed, occurred in public, and whether bystander CPR was administered. Levels of arachidonic acid and trans-18:2 fatty acids were associated with SCA survival ( Table ). An increase of one SD in levels of arachidonic acid was associated with decreased likelihood of survival to both hospital admission and hospital discharge (OR (95% CI), uncorrected p-value: 0.75 (0.62-0.92), p =0.006 and 0.69 (0.55, 0.87), p =0.002, respectively). A one SD difference in trans-18:2 fatty acid levels was associated with decreased likelihood of survival to hospital discharge (0.74 (0.57-0.96), p =0.02)). Levels of n-3 PUFAs and trans-18:1 fatty acids were not associated with SCA survival. Our findings suggest arachidonic acid and trans-18:2 may influence SCA survival. Further work is needed to explore the role of fatty acid metabolism in heart and brain resuscitation. Association of Erythrocyte Fatty Acids with Resuscitation Outcomes Survival to hospital admission Survival to hospital discharge OR * (95% CI) p-value OR * (95% CI) p-value n-3 fatty acids α-Linolenic acid 1.01 (0.83-1.22) 0.95 0.85 (0.67-1.07) 0.60 EPA+DHA 1.05 (0.87-1.28) 0.60 1.10 (0.87-1.38) 0.44 n-6 fatty acids Linoleic acid 0.97 (0.80-1.18) 0.77 1.05 (0.83-1.33) 0.66 Arachidonic acid 0.75 (0.62-0.92) 0.006 0.69 (0.55-0.87) 0.002 Trans-fatty acids Trans-18:1 1.06 (0.87-1.29) 0.56 1.06 (0.84-1.34) 0.47 Trans-18:2 0.99 (0.80-1.22) 0.93 0.74 (0.57-0.96) 0.02 * OR corresponding to one SD higher levels

Advanced Rescuer- versus Citizen-Witnessed Cardiac Arrest: Is There a Difference in Outcome??

Background. Substantial financial and human resources are invested in training and maintaining advanced life support (ALS) skills of paramedics who are deployed to the field in response to out-of-hospital cardiac arrest. It would be expected that patients who experience cardiac arrest in the presence of a trained health care practitioner, such as a paramedic, have better outcomes. Objective. To compare the rates of return of spontaneous circulation (ROSC), survival to hospital admission (SHA), and survival to hospital discharge (SHD) between paramedic-witnessed out-of-hospital cardiac arrest vs. citizen-witnessed out-of-hospital cardiac arrest. Methods. In this retrospective cohort study, the records of all out-of-hospital nontraumatic cardiac arrest patients presenting to a municipal teaching hospital from November 1, 1994, through June 30, 2008, were reviewed. The age, gender, race, rhythm on paramedic arrival, presence of bystander cardiopulmonary resuscitation (CPR), whether it was a witnessed arrest and, if witnessed, whether it was a paramedic-witnessed arrest, site of the arrest, and the rate of SHD were noted. A univariate odds ratio was computed to describe the association between paramedic-witnessed out-of-hospital cardiac arrest vs.citizen-witnessed out-of-hospital cardiac arrest and SHD. A multivariable logistic regression analysis was also performed, controlling for age, gender, arrest rhythm, bystander CPR, and site of arrest. Results. Of the total cohort of 1,294 out-of-hospital cardiac arrests, 750 (52.6%%) were either paramedic-witnessed (154/750 == 20.5%%) or citizen-witnessed (596/750 == 79.5%%). Among the witnessed cardiac arrests, overall the SHD was 53 of 750 (7.1%%). On univariate analysis, the ROSC, SHA, or SHD rates were not statistically significantly different between paramedic- and citizen-witnessed arrests. Even after multivariable adjustment, the ROSC, SHA, and SHD rates were not significantly different between paramedic- and citizen-witnessed arrests. Conclusions. Among our study population of out-of-hospital cardiac arrest victims, paramedic-witnessed arrests did not appear to have improved survival rates when compared with citizen-witnessed arrests. Key words: cardiac arrest; cardiopulmonary resuscitation; advanced life support; basic life support