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Double sequential defibrillation strategy for cardiac arrest with refractory shockable rhythm; ALS TF SR

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This CoSTR is a draft version prepared by ILCOR, with the purpose to allow the public to comment and is labeled “Draft for Public Comment". The comments will be considered by ILCOR. The next version will be labelled “draft" to comply with copyright rules of journals. The final COSTR will be published on this website once a summary article has been published in a scientific Journal and labeled as “final”.

Conflict of Interest Declaration

The ILCOR Continuous Evidence Evaluation process is guided by a rigorous ILCOR Conflict of Interest policy. The following Task Force members and other authors were recused from the discussion as they declared a conflict of interest: none

The following Task Force members and other authors declared an intellectual conflict of interest and this was acknowledged and managed by the Task Force Chairs and Conflict of Interest committees: Ian Drennan was a co-investigator on the RCT of defibrillation strategies (Cheskes 2022) included in this systematic review, and therefore did not participate in the study selection or bias assessment steps of the review. He declared his intellectual COI during all discussions about the included trial and draft treatment recommendations.

CoSTR Citation

Ohshimo S, Drennan I, Deakin CD, Soar J, Berg KM; on behalf of the International Liaison Committee on Resuscitation Advanced Life Support Task Force. Double Sequence Defibrillation, Consensus on Science with Treatment Recommendations [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) Advanced Life Support Task Force, 2022 December 3. Available from: http://ilcor.org

Methodological Preamble

The continuous evidence evaluation process for the production of Consensus on Science with Treatment Recommendations (CoSTR) started with a systematic review conducted on behalf of the ALS task force in 2020.{Deakin 2020 24} Due to the publication of a new RCT, an updated systematic review was performed. (PROSPERO registration CRD42022365305, registered on October 17, 2022) These data were taken into account by the task force when formulating the treatment recommendations.

PICOST

The PICOST (Population, Intervention, Comparator, Outcome, Study Designs and Timeframe)

Population: Adults in any setting (in-hospital or out-of-hospital) with cardiac arrest and a shockable VF/pVT cardiac arrest rhythm.

Intervention: Double sequential defibrillation strategy

Comparators: Standard defibrillation strategy

Outcomes: Critical – Survival to hospital discharge or good neurological survival at discharge/30 days, or greater than 30 days. Important – Return of Spontaneous Circulation (ROSC), survival to hospital admission. Other – termination of VF/pVT

Study Designs: Randomized controlled trials (RCTs) and non-randomized studies (non-randomized controlled trials, interrupted time series, controlled before-and-after studies, cohort studies) are eligible for inclusion. Unpublished studies (e.g., conference abstracts, trial protocols) are excluded. All relevant publications in any language are included as long as there is an English abstract.

Timeframe: All years and all languages were included as long as there was an English abstract; unpublished studies (e.g., conference abstracts, trial protocols) were excluded. Literature search for this update included studies published from February 28, 2020 to November 7, 2022.

PROSPERO Registration Submitted October 17, 2022

Consensus on Science

This CoSTR is an update of the 2020 systematic review (Deakin 2020 ilcor.org). This updated systematic review identified one additional RCT (Cheskes 2022 1). No new observational studies were identified since the prior review. As was reported in the 2020 CoSTR, all observational studies previously identified were at critical risk of bias due to confounding, and individual results are thus difficult to interpret. Similarly, the results of the previous pilot RCT (Cheskes 2020) have been removed as these patients are included as an internal pilot study of the included RCT (Cheskes 2022). Although the initial search was conducted to identify studies comparing double sequence defibrillation (DSED) with standard defibrillation, the single identified trial compared DSED and vector change (VC, anterior-posterior pad placement) with standard (anterior-lateral) defibrillation (SD). The task force thought it was important to address both comparisons, so this CoSTR includes the data comparing VC with SD as well as that comparing DSED with SD. Data were not available for adjusted statistical comparison of DSED with VC, as the trial was not designed for that comparison and this post-hoc analysis could not be obtained. All calculations of adjusted relative risk (aRR) were adjusted for cluster (cluster randomized trial), age, sex and receipt of lay rescuer CPR. Absolute risk difference has not been provided here due to reliance on adjustment for the relative risk. The unadjusted relative risk and associated absolute risk difference are provided in the associated GRADE tables, along with the primary adjusted results. The adjusted results are generally more conservative than the unadjusted.

Double sequential defibrillation (DSED) compared with standard defibrillation (SD)

For the critical outcome of favorable functional survival at discharge (defined as modified Rankin Score (mRS) of 0-2), we identified low certainty evidence (downgraded for serious risk of bias and imprecision) from a single cluster randomized controlled trial (Cheskes 2022) including 261 patients which found improved functional outcome with DSED compared with SD (27.4% vs 11.2%, adj RR 2.21 [95% CI 1.26, 3.88]).

For the critical outcome of survival to hospital discharge, we identified low certainty evidence (downgraded for serious risk of bias and imprecision) from a single cluster randomized controlled trial (Cheskes 2022) of 261 patients which found improved survival to hospital discharge with DSED compared with SD (30.4% vs 13.3%, adj RR 2.21 (95% CI 1.33, 3.67).

For the important outcome of return of spontaneous circulation (ROSC) we identified low certainty evidence (downgraded for serious risk of bias and imprecision) from a single cluster randomized controlled trial (Cheskes 2022) of 261 patients which found improved rate of ROSC with DSED compared with SD (46.4% vs 26.5%, adj RR 1.72 (95% CI 1.22, 2.42)).

For the important outcome of termination of ventricular fibrillation (VF) we identified low certainty evidence (downgraded for serious risk of bias and imprecision) from a single cluster randomized controlled trial (Cheskes 2022) of 261 patients which found a higher rate of termination of VF with DSED compared with SD (84% vs 67.6%, adj RR 1.25 (95% CI 1.09, 1.44)).

No studies were identified for cardiac arrest occurring in the in-hospital setting. The same evidence therefore provides very low certainty evidence (downgraded additionally for indirectness) for the effect of DSED compared with SD on the outcomes above for patients with refractory VF in the in-hospital setting.

Vector change defibrillation (VC) compared with standard defibrillation (SD)

For the critical outcome of favorable functional survival at discharge (defined as modified Rankin Score (mRS) of 0-2), we identified very low certainty evidence (downgraded for serious risk of bias and very serious imprecision) from a single cluster randomized controlled trial (Cheskes 2022) including 280 patients which found no significant benefit from VC compared with SD (16.2% vs 11.2%, adj RR 1.48 [95% CI 0.81, 2.71]).

For the critical outcome of survival to hospital discharge, we identified low certainty evidence (downgraded for serious risk of bias and imprecision) from a single cluster randomized controlled trial (Cheskes 2022) of 280 patients which found improved survival to hospital discharge with VC compared with SD (21.7% vs 13.3%, adj RR 2.21 (95% CI 1.01,2.88).

For the important outcome of return of spontaneous circulation (ROSC) we identified very low certainty evidence (downgraded for serious risk of bias and very serious imprecision) from a single cluster randomized controlled trial (Cheskes 2022) of 280 patients which found no significant improvement in ROSC with VC compared with SD (35.4% vs 26.5%, adj RR 1.39 (95% CI 0.97, 1.99)).

For the important outcome of termination of ventricular fibrillation (VF) we identified low certainty evidence (downgraded for serious risk of bias and imprecision), from a single cluster randomized controlled trial (Cheskes 2022) of 280 patients which found a higher rate of termination of VF with VC compared with SD (79.9% vs 67.6%, adj RR 1.18 (95% CI 1.03, 1.36)).

No studies were identified for cardiac arrest occurring in the in-hospital setting. The same evidence therefore provides very low certainty evidence (downgraded additionally for indirectness) for the effect of VC compared with SD on the outcomes above for patients with refractory VF in the in-hospital setting.

Treatment Recommendations

We suggest that a double sequential defibrillation strategy (weak recommendation, low certainty of evidence) or a vector change defibrillation strategy (weak recommendation, very low certainty of evidence) may be considered for adults with cardiac arrest who remain in ventricular fibrillation or pulseless ventricular tachycardia after 3 or more consecutive shocks.

If a double sequential defibrillation strategy is utilized, we suggest an approach similar to that in the available trial, with a single operator activating the defibrillators in sequence. (good practice statement)

Justification and Evidence to Decision Framework Highlights

The task force discussed the following points in the process of reaching consensus on the treatment recommendations:

  • Current evidence does not permit distinguishing whether either strategy (double sequential defibrillation or vector change defibrillation) is superior to the other.
  • The task force emphasized the importance of proper pad placement to optimize the efficacy of standard defibrillation. While prior ILCOR statements have recommended anterior-lateral pad placement without further specification (Jacobs 2010 S325) and a recent scoping review by the BLS task force did not identify new evidence to alter that treatment recommendation (Ristagno 2019 ilcor.org), the ALS task force agreed with the more specific descriptions of anterior-lateral pad placement provided in existing guidelines from the American Heart Association and the European Resuscitation Council. These guidelines recommend that defibrillation pads are placed to anatomically encompass the heart (with one pad below the right clavicle, just to the right of the upper sternal border and the other with the center of the pad in the left mid-axillary line) and that adequate contact is made at the pad-skin interface so as to optimize energy (current) delivery. (de Latorre 2001 211; Circulation 2000 I-90) The task force discussed the importance of ensuring correct pad placement for standard defibrillation before progressing to DSED or VC defibrillation.
  • Approximately 20% of VF patients will remain in VF despite standard resuscitation interventions. Patients in refractory VF have significantly lower rates of survival than patients who respond to standard resuscitation treatments.
  • Double shocks require the availability of two defibrillators and this has resource implications. The Task force noted that double sequential defibrillation is already used by some EMS systems for refractory shockable cardiac arrest and therefore may be easily implemented in some systems. In other systems this practice could require significant new resource allocation for additional defibrillators or ambulances, and the task force acknowledged that such an increase in resource allocation may not be justified based on a single relatively small study.
  • Studies (van Alem 2003 181; Bhandari 2018 22) have shown that that refractory VF is in fact most often due to recurrent VF following successful defibrillation rather than due to a failure to be terminated by shock (unsuccessful defibrillation). This difference may not be recognized clinically because of ongoing CPR during the period between shocks, but may be important since recurrent VF may require alternative approaches to stabilize the rhythm, once terminated, to prevent recurrence. Future “see through CPR” algorithms (enabling detection of underlying rhythm during CPR) may permit distinguishing patients with incessant refractory VF from recurrent VF after shock delivery, and thus better direct electrical vs pharmacologic or other therapies toward each entity.
  • The available evidence for the double defibrillation approach is limited as there is only a single cluster randomized trial, which was prematurely terminated for logistical concerns when they had reached approximately half of their planned sample size. Confidence intervals were not adjusted for multiplicity, and the TF discussed the concern that a single smaller-than-planned study leaves significant uncertainty about treatment effect.
  • There is no agreed standardised approach to double defibrillation such that a double dose strategy could be two overlapping shocks or sequential shocks. TF discussed the lack of evidence for the ideal approach, but felt it important to highlight that there has been concern about possible defibrillator damage with simultaneous shocks. The protocol used in the existing trial, with a single person activating two defibrillations in quick succession (but not simultaneous) did not result in any reports of defibrillator damage and is therefore likely the best approach to use currently.
  • Sequential shocks being beneficial does not mean that a single higher energy shock would be beneficial, and the importance of not equating two sequential shocks with a single higher-energy shock was highlighted.
  • Current evidence does not permit distinguishing whether the vector change or the double shock employing the vector change in addition to standard defibrillation accounts for the observed benefit. The task force had extensive discussions about whether the anterior-posterior pad placement or the double sequential defibrillation provided most of the benefit seen.
  • The limited observational data show lower rates of survival and neurological outcome for patients treated with double defibrillation, although the prior systematic review rated these studies as at critical risk of bias.
  • Sensitivity analyses included in the available trial did not see a difference in outcomes with DSED when patients were analysed by treatment received rather than intent to treat (randomization group). Reasons why certain patients received a defibrillation strategy other than that to which they were randomized are not known.

It is unusual for intra-arrest interventions to have a more statistically significant effect on survival and neurologic outcome than on ROSC and VF termination, as was seen in the included trial.

Knowledge Gaps

  • Whether the benefit from DSED seen in this single trial will be replicated in other settings.
  • Whether DSED is beneficial compared to changing pad placement (vector change defibrillation) is unclear.
  • The optimal timing of shock delivery when a DSED strategy is used.
  • Whether DSED has an effect on health-related quality of life.

Attachment:

DSD Et D DSD vs SD 2022 March 3

DSD Et D VC vs SD 2022 March 3

DSD GRADE DSD vs SD 2022 Nov 30

DSD GRADE VC vs SD 2022 Nov 30

References

  1. Beck LR, Ostermayer DG, Ponce JN, Srinivasan S, Wang HE. Effectiveness of Prehospital Dual Sequential Defibrillation for Refractory Ventricular Fibrillation and Ventricular Tachycardia Cardiac Arrest. Prehosp Emerg Care 2019;23:597-602.
  2. Bhandari S, Doan J, Blackwood J, Coult J, Kudenchuk P, Sherman L , Rea T and Kwok H. Rhythm profiles and survival after out-of-hospital ventricular fibrillation cardiac arrest. Resuscitation. 2018. April;125:22-27.
  3. Cabañas JG, Myers JB, Williams JG, De Maio VJ, Bachman MW. Double Sequential External Defibrillation in Out-of-Hospital Refractory Ventricular Fibrillation: A Report of Ten Cases. Prehosp Emerg Care. 2015;19:126-130.
  4. Cheskes S, Wudwud A, Turner L, McLeod S, Summers J, Morrison LJ, Verbeek PR. The impact of double sequential external defibrillation on termination of refractory ventricular fibrillation during out-of-hospital cardiac arrest. Resuscitation. 2019;139:275-281.
  5. Cheskes S, Verbeek PR, Drennan IR, McLeod SL, Turner L, Pinto R, Feldman M, Davis M, Vaillancourt C, Morrison LJ, Dorian P, Scales DC. Defibrillation strategies for refractory ventricular fibrillation. N Engl J Med 2022 (in press).
  6. Cheskes S, Dorian P, Feldman M, McLeod S, Scales DC, Pinto R, Turner L, Morrison LJ, Drennan IR, Verbeek PR. Double sequential external defibrillation for refractory ventricular fibrillation: The DOSE VF pilot randomized controlled trial. Resuscitation 2020;150:178-184.
  7. Cortez E, Krebs W, Davis J, Keseg DP, Panchal AR. Use of double sequential external defibrillation for refractory ventricular fibrillation during out-of-hospital cardiac arrest. Resuscitation. 2016;108:82-86.
  8. De Latorre F, Nolan J, Robertson C, Chamberlain D, Baskett P, European Resuscitation Council. European Resuscitation Council Guidelines 2000 for Adult Advanced Life Support. A statement from the Advanced Life Support Working Group(1) and approved by the Executive Committee of the European Resuscitation Council. Resuscitation Mar 2001;48(3):211-21.
  9. Emmerson AC, Whitbread M, Fothergill RT. Double sequential defibrillation therapy for out-of-hospital cardiac arrests: The London experience. Resuscitation. 2017;117:97-101.
  10. Mapp JG, Hans AJ, Darrington AM, Ross EM, Ho CC, Miramontes DA, Harper SA, Wampler DA; Prehospital Research and Innovation in Military and Expeditionary Environments (PRIME) Research Group. Prehospital Double Sequential Defibrillation: A Matched Case-Control Study. Acad Emerg Med. 2019;26:994-1001.
  11. Merlin MA, Tagore A, Bauter R, Arshad FH. A case series of double sequence defibrillation. Prehosp Emerg Care 2016;20:550-553.
  12. Ristagno G, Mancini MB, Avis S, Brooks S, Castren M, Chung S, Considine J, Kudenchuk P, Perkins GD, Semeraro F, Smith C, Smyth M , Morley PT, Olasveengen TM -on behalf of the International Liaison Committee on Resuscitation Basic Life Support Task Force. Pad size, orientation and placement for Cardiac Arrest - Consensus on Science with Treatment Recommendations [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) Basic Life Support Task Force, 2019 Dec 30th. Available from: http://ilcor.org
  13. Ross EM, Redman TT, Harper SA, Mapp JG, Wampler DA, Miramontes DA. Dual defibrillation in out-of-hospital cardiac arrest: A retrospective cohort analysis. Resuscitation. 2016;106:14-7.
  14. Van Alem AP, Post J, Koster RW. VF recurrence: characteristics and patient outcome in out-of-hospital cardiac arrest. Resuscitation 2003. Nov;59:181-8.
  15. Part 6: AHA Advanced Cardiovascular Life Support Guidelines., Circulation, Volume 102, Issue suppl_1: I-90–I-94, August 22, 2000.
Advanced Life Support
Defibrillation and Electrical Therapy

Discussion

GUEST
Kate Berg

(modified: )

The ALS TF thanks all of those who have provided comments. We have taken all comments into consideration, and agree that we cannot tell from the evidence to-date whether DSED or VC is superior to the other. We have therefore amended our treatment recommendation to clarify that either strategy can be considered, while acknowledging that the certainty of evidence is slightly lower for VC than for DSED. We also agree that consideration of pad placement is important, and have discussed this in the evidence-to-decision and justification section. We agree that a future review looking specifically at how pad placement affects outcome may be important. We have also emphasized that if DSED is used, the approach used in the trial should be followed, as they did not report any defibrillator damage with their approach.

Previous Comments by viewers

Sheldon Cheskes

2022.12.15 18:29:32

Conflicts of interest: Grants

We thank the ILCOR task force for their careful review of our trial. We would like to provide some clarity regarding the trial methodology and respectfully challenge some of the rationale behind the downgrading of the quality of the evidence The task force rated down for Risk of Bias (RoB) and Imprecision. The explanation provided by the task force for rating down for RoB was that paramedics weren't blinded to the defibrillation strategy. In our opinion, this does not represent an important source of bias in the trial for the following reasons: (1) Paramedics did not choose to enroll individual patients; rather patients were enrolled if they met eligibility criteria and were allocated to a defibrillation strategy according to the cluster randomization; (2) all outcomes were objective and unlikely to be influenced by any subjective assessments; (3) our results showed that quality of CPR was excellent across groups, with no important differences in scene time, drug administration, or time to drug administration; if conscious or unconscious bias was a concern, one would expect these to be different (e.g., paramedics might spend less time on scene if standard care was thought to be inferior, or frequently crossover from standard to other interventions). The statement also notes that paramedics determined some secondary outcomes (VFT and ROSC). This is inaccurate: VFT was never determined by paramedics but was determined by blinded abstractors after review of each case; paramedics determined ROSC but this was according to standard practice and each case was independently reviewed and verified by the medical director or local site investigator. We do not believe these approaches to outcome assessment would have introduced important bias – and we would argue the task force should not have downgraded for Risk of Bias due to lack of blinding. The task force also downgraded for imprecision. We would argue the task force should not have downgraded for imprecision for the DSED vs standard comparison, but we are comfortable with the decision to downgrade for imprecision for the VC vs standard comparison. GRADE suggests an approach that relies on thresholds and CIs of the absolute effect (CI approach) as a primary criterion for imprecision rating, NOT the optimal information size approach. We therefore disagree with the stated rationale which currently says, "Optimal information size not met. Using the hypothesized survival rate with standard defibrillation in the original trial (12%) and the hypothesized absolute increase in survival of 8% for both DSED and VC, a sample size of 310 patients per study group was calculated by the authors. The actual sample size of 125 (DSED), 136 (SD) and 144 (VC) was well below this number, introducing the possibility of imprecision in the results". Note that the absolute increase in survival for DSED was actually 17% not 8%, suggesting the hypothesized effect size for DSED used in the sample size was likely an underestimate. In our opinion, the thresholds and CIs of the effect for DSED (aRR 2.21, 95% CI 1.33 to 3.67) were not close to 1 and do not suggest imprecision. We appreciate the opportunity to comment and welcome any feedback from the ILCOR task force.


Response from ALS Chair Kate Berg: Thank you Dr. Cheskes for the comments regarding your trial. Risk of bias and certainty of evidence were discussed extensively with the task force, and decisions were not easy to come to. The task force opinion is that there is a potential risk of bias in unblinded studies (unavoidable in this case) because whether the study intervention or a different intervention is used may depend on the clinician’s opinion about the intervention or their opinion about the specific patient. There was a significant amount of crossover between the 3 study treatments, which was not evenly distributed. Exactly why this occurred or how it could have influenced the results is not entirely clear, but the task force felt that this may indicate a potential source of risk of bias. Thank you for clarifying how termination of VF/VT was determined. We can make that adjustment in the relevant GRADE tables. Regarding the assessment of imprecision, we think the optimal information size was appropriate to invoke. GRADE recommends the optimal information size (OIS) as a “second, necessary criterion to consider.” The concept of optimal information size is meant to prompt downgrading for imprecision when you do not think the sample size was adequate to be a true population estimate, based on a conventional sample size calculation. Since the goal is to detect when an effect size reported in a smaller trial may not reflect the true effect size, systematic reviewers are advised to calculate a sample size based on relative risk difference of 20-30%, not on the effect size observed in the trial in question (see GRADE handbook section on imprecision 5.2.4.1, #2 under “dichotomous outcomes,” and then see Example 3). We thought the original sample size calculation conducted by your group was reasonably close to the GRADE recommendation for that calculation so relied on that for the OIS. The fact that survival increased more than your group initially hypothesized is notable and may reflect the true effect, but there is risk of overestimation of treatment effect when trials are stopped early (Liu et al, Trials 23, 747, Sept 2022; Guyatt et al, BMJ ;344:e3863, 2012), so we think determining OIS based on a more conservative sample size calculation is prudent. Overall, the task force opinion is that a single trial of approximately 130 patients per study group almost by definition cannot provide higher certainty evidence for what is a considerable practice change, and we think GRADE methodology supports that determination.
Fred Chapman

2022.12.19 21:39:47 (modified: 2022.12.21 22:04:26)

Conflicts of interest: Financial relationships

I appreciate the ILCOR task force’s prompt analysis of the DOSE VF Trial. There are a few details that I would like to submit for consideration. First, the primary endpoint of the trial showed that both vector change (VC) and DSD had a benefit over standard care. The trial stopped early, was consequently underpowered and did not compare VC and DSD, so cannot provide accurate relative assessment of the two techniques. That the CoSTR recommends DSD over VC is not consistent with these limitations and is not consistent with the authors’ conclusion in the paper. Due to the limited information available through this trial, it may be premature to draw a conclusion on the superiority or inferiority of VC and DSD Second, it is worth noting that it is likely that none of the defibrillators available today were designed for DSD, and that DSD may be an off-label use of these devices. Defibrillator damage can occur with some DSD techniques, as has been reported in the literature, but was reported not to have occurred in DOSE VF. It is appropriate you have included the statement: “If a double sequential defibrillation strategy is utilized, we suggest an approach similar to that in the available trial, with a single operator activating the defibrillators in sequence. (good practice statement)”. A second aspect of the DSD practiced in the trial is also worth reinforcing: the specific choice of anterior-lateral and anterior-posterior pad placement for the two shock vectors. Other DSD vectors and other shock timing practices may have higher risk of incapacitating the defibrillator. Lastly, I am concerned that the comment period for this complex topic is ending too early for there to have been robust comment from the public. No letters to the editor in response to the report of the single cluster-randomized study published in NEJM have even yet been published. It may be beneficial to extend the comment period and increase visibility to this draft through appropriate channels. I would like to sincerely thank the ILCOR task force for your consideration of these comments.

ILCOR staff

2023.01.19 10:01:01 (modified: 2023.01.19 10:02:58)

From ALS Chair Kate Berg: Response: Dr. Chapman, thank you very much for your comments. First, while we agree that the available data did not allow for statistical comparison of DSED and VC, it is also the case that DSED compared with SD showed statistically significant benefits for all outcomes, while this was not the case for VC compared with SD. This is why the TF came to the conclusions it did, after extensive discussion. We include some of this discussion in the evidence to decision section and have included it as a knowledge gap. We agree about the importance of the sample size being smaller than planned due to the trial stopping early, and that the effect size might be an overestimate, which is why the evidence was downgraded for imprecision. The lack of comparison between DSD and VC, however, was not as a result of stopping the study early. The study was never designed to compare DSD to VC. Second, we agree that none of the currently available defibrillators are designed for DSED. We have discussed the importance of pad placement for SD, possible concerns about defibrillator damage and the reasoning for recommending the approach (single operator activating the shock with one hand, sequentially) used in the trial as well, as we agree that these are important considerations. Third, we are happy to ask ILCOR leadership to extend the public comment period.

John Mouw
2023.01.25 08:35:56 (modified: 2023.01.31 04:06:09)
On a practical note, the resources both in cost to increase defibrillator availability and competency training to perform DSED would be higher than with VC. For this reason and others, a DSED to VC comparison study is needed. Until a single DSED defibrillator is manufactured a meaningful DSED to VC comparison will prove challenging.

Dominic Larose

2023.01.30 14:46:23 (modified: 2023.01.31 04:00:37)
I agree that before considering VC or DSD, proper position of the defibrillation electrodes should be optimal. Many physicians do not position the left electrode in the optimal, mid axillary position. Most place it too anteriorly. (Heames RM, Sado D, Deakin CD. Do doctors position defibrillation paddles correctly? Observational study. BMJ. 2001 Jun 9;322(7299):1393-4. doi: 10.1136/bmj.322.7299.1393. PMID: 11397743; PMCID: PMC32253.). In a study of manufacturers illustration of paddle position, it was found that none of them showed the ideal one. (Foster AG, Deakin CD. Accuracy of instructional diagrams for automated external defibrillator pad positioning. Resuscitation. 2019 Jun;139:282-288. doi: 10.1016/j.resuscitation.2019.04.034. Epub 2019 May 5. PMID: 31063839.) Training manikins also shows a sub-optimal position (https://laerdal.com/ca/informa...). AHA videos, such as this one at 7:08 min shows an incorrect position https://www.youtube.com/watch?.... I suggest to change the wording of anterolateral position (even worse: antero-apical) to antero-axillary. That one of the most important therapy for VF cardiac arrest is not done or teached in an optimal fashion should be a cause of great concern for the ILCOR comitee. There should be great emphasis to better teach proper position of the defibrillating pads in future training materials.

Dominic Larose

2023.01.31 08:23:37 (modified: 2023.02.01 21:41:19)

The study was done with a rectilinear biphasic defibrillator at 200J. Most likely the conclusion would be the same with a biphasic truncated exponential defibrillator at 360J, but of course this can't be known for sure unless this would be tested.


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