In-Hospital Defibrillation

The new Guidelines 2000 are largely unchanged from the content of the previous Textbook of ACLS, but there have been a few improvements: the specific ILCOR recommendation that caregivers below the full paramedic level use only AEDs has apparently been dropped. Generally, though, the treatment of AED technology is remakably uncritical, ignoring the limitations that we addressed in the worksheet. Also, the 1980 article by Eisenberg et al. is still called an AED study!

Since the Guidelines came out, several animal studies have confirmed that pauses in CPR for AED rhythm analysis decrease shock efficacy and survival. These are mostly from Max Harry Weil and colleagues in Palm Springs.

The complete worksheet may be viewed or downloaded here.

AEDs and trained caregivers

Relevant passages from existing guidelines and training materials

From the ILCOR Advisory Statement "Early Defibrillation" (Circulation. 1997;95;2183-2184):

ILCOR recommends that early defibrillation programs by nonmedical ambulance personnel…use only AEDs (except for fully trained paramedics, who may use manual defibrillators by local agreement).

ILCOR recommends that [early defibrillation programs for nonphysician in-hospital responders]…establish and encourage AED training as a basic skill for healthcare providers working in settings where advanced life support (ALS) professionals are not immediately available.

From "In-Hospital Resuscitation: A Statement for Healthcare Professionals," Circulation 1997; 95: 2211-2212:

All hospital staff who may need to respond to a sudden cardiopulmonary emergency are trained in basic life support (BLS) and, when appropriate, in the use of automated external defibrillators (AEDs). Such AED training is considered a basic skill for healthcare providers, particularly when professionals trained in ALS are not immediately available. Staff members maintain their CPR and AED skills with regular refresher training.

In the Textbook of ACLS:

Section 4.5, titled "Importance of Automated External Defibrillation."

Section 4.6, titled "Advantages and Disadvantages of Automated External Defibrillators."

Section 4.7.14, titled "In-hospital Use of AEDs: Delays in Defibrillation."

Discussion

We recommend that the American Heart Association (AHA) and the International Liason Committee on Resuscitation (ILCOR) avoid recommending AED technology prematurely in settings other than public access defibrillation (PAD). AED defibrillation has been shown to be better than no defibrillation, and in side by side trials of limited power, has produced outcomes similar to manual defibrillation. This does not justify mandating that caregivers who may be required to treat ventricular fibrillation (VF) should use AEDs exclusively, as the ILCOR guideline states.

In addition, several passages in AHA publications inaccurately equate early defibrillation with use of AEDs and have the effect of imparting an overly optimistic assessment of the technology. EMT and in-hospital early defibrillation programs started with manual defibrillators,[Eisenberg 1980,  MacKintosh 1979], but current accepted wisdom seems to be that AED technology will be the foundation of all early-defibrillation programs. From the Textbook of ACLS, Section 4.5:

Defibrillation was once a skill reserved for emergency care providers trained in all aspects of ACLS, but it is now performed by BLS personnel who have less training. The availability of AEDs has sparked this extension of defibrillation capability and permitted wider achievement of earlier defibrillation. [Eisenberg 1984]

The reference supplied [Eisenberg 1984] does not support AED use: the referenced article describes the success an early EMT-D program using manual defibrillators and does not mention AEDs. The AHA in recent years has appeared to equate early defibrillation almost completely with use of AEDs--even in the hospital setting, where manual defibrillators are usually immediately available. Section 4.7.14 of the current Textbook of ACLS recommends that hospitals purchase and use AEDs to deal with delayed defibrillation and fails to address possible alternatives using existing equipment. This issue has been raised previously [Stewart JA 1996], but no changes have yet been made in response to the recommendation.

The majority of studies on the efficacy of AEDs compare AED treatment to treatment with CPR only and without early defibrillation. Those studies were excluded from our present review. The only clinical studies which have directly compared AED defibrillation with manual defibrillation have concluded only that outcomes were comparable with AEDs and manual defibrillators. [Stults 1986, Cummins 1987, Schrading 1993]

The principal rationale for the wide promotion of AED technology for healthcare providers is the presumed brevity and ease of training, which in theory makes early defibrillation available to more people (Other considerations come into play with public access defibrillation, as the ILCOR guideline acknowledges in stating that lay rescuers should "use only AEDs; practical considerations render manual defibrillators inadvisable for lay use." This statement contrasts with the prohibition for professional rescuers, which makes no attempt to provide a rationale.) A technology offering comparable clinical performance to manual defibrillators is arguably better in practical terms if the technology also makes training significantly easier. However, the assumed training advantage of AEDs has little science behind it. Automated rhythm analysis has been assumed to be a major advance in ease of use, precluding the need for users to learn arrhythmia diagnosis. Implantable defibrillators obviously require automated shock decisions, but the need for automatic rhythm analysis with external defibrillation is unclear because a human operator must be present in any case to identify cardiac arrest and connect the device. Though it is typically maintained by AED advocates that use of a manual defibrillator requires advanced knowledge of ECG analysis and rhythm recognition, there is no good evidence that simply distinguishing shockable arrhythmias is a major problem in defibrillation training, and some evidence exists to the contrary [Stewart AJ 1994,  Bradley 1988].

Although the 1994 Textbook of ACLS stated that AEDs, in contrast to manual defibrillators, require only "brief, convenient training sessions and minimal continuing education," the sole reference cited for this statement could more appropriately be used to refute it [Bradley 1988]. (The citation was replaced in the 1997 revision by a reference to a 1985 article which discussed issues related to AED training for lay in-home rescuers and contained no quantitative data.  [Cummins 1998]) The Bradley study compared a four-hour manual defibrillation course with a ten-hour course and found no significant difference in tested performance between the two groups at one week and 18 months, concluding that much of the material in the longer manual defibrillation course was irrelevant to performing the skill. Studies contrasting brief AED training with longer training for manual defibrillation tend to base their favorable comparisons on the fact that the investigators allocated a certain number of hours to each type of training and the students seemed to perform adequately. Schrading et al. [Schrading 1993] used 9-hour AED and 20-hour manual defibrillation courses and concluded that manual defibrillation "required" 11 more training hours. The same reasoning can be used to show that AED training "requires" 20 hours. [Mols 1994]

The ease-of-training argument is perhaps clearest in the context of in-hospital defibrillation, where manual defibrillators are typically quickly accessible. To an AED advocate

[a] conventional defibrillator…is a complicated high-tech device with a monitor and a strip-chart recorder…. The operator must recognize arrhythmias, decide if the arrhythmia present is one that can be treated by administering a shock, select the energy level for the shock, charge the device, and push a button or buttons to deliver the shock…. Extensive initial and ongoing training is required, both in recognition of arrhythmias and in operation of the conventional defibrillator. [Mancini 1998]

To a caregiver familiar with manual defibrillation, the task (using a defibrillator with defaults set to "paddles" and "200 joules") might look more like this:

Push the ON button, place the disposable conductive precordial pads, press the paddles firmly to the chest, look for the characteristic chaotic pattern of VF, press the charge button, clear contact with the patient, and press the discharge buttons.

The majority of studies of AED training are hampered by lack of uniform performance criteria, absence of a control group, and questionable test conditions which provide subjects at least a few minutes to mentally review the procedure before being tested. Reproducing the stressful setting of a sudden cardiac arrest is of course impossible, but it is at least possible to do true surprise testing in many institutional settings. The best study of side-by-side AED and manual defib training [Fromm 1997] did such testing in a hospital with lay rescuers who had received very minimal training, and it did show much better performance in the AED group than in a control group using an older model of manual defibrillator (without user-configurable defaults for lead selection and energy level). Interestingly, the investigators required only blind manual defibrillation, thus eliminating the supposed hurdle of ECG analysis. This study showed that, for a group of users without patient care experience, the AED was easier to use for reasons unrelated to the central rationale for AEDs (automated rhythm recognition). It suggests that some of the ergonomic improvements which have accompanied the development of AEDs (e.g., simplified controls and voice prompts) have value in themselves apart from the core technology, and could be applied to manual defibrillator design as well.

In order to promote a more realistic view of AED technology, we propose some specific changes in the Textbook of ACLS and other AHA literature.

1. Include under "Advantages and disadvantages of AEDs" the need to withhold chest compressions during an interval for rhythm analysis. This is a disadvantage of AEDs in comparison to manual defibrillators and should be explicitly listed as such (it is presently referred to in another section as a necessary trade-off to permit early defibrillation). The animal study by Sato et al. [Sato 1997] offers persuasive evidence that when chest compressions are withheld for short intervals prior to a shock, the likelihood of conversion decreases significantly. In addition, American Heart Association training materials have for many years stressed the importance of not halting CPR for more than five seconds and have taught rather involved procedures to prevent such pauses-when switching places during two-person CPR, for example.

2. Drop the assertion that AEDs deliver the first shock faster than manual defibrillators in the hands of EMTs. This finding in the two studies cited to support it [Stults 1986, Cummins 1987] has been contradicted by one subsequent clinical study [Schneider 1994] and a training study [Domanovits 1998] with better methodology for determining time intervals; the Domanovits study showed that trained caregivers were significantly faster with manual defibrillators. It is likely that use of "quick-look" paddles would result in significantly faster times to first shock with manual defibrillators. [Stewart JA 1997] Though the great majority of EMT-Defibrillation protocols do not use quick-look paddles, we have found no data in the literature to preclude their use. The switch from precordial quick-look paddles to 3-lead ECG for initial monitoring was made in one EMT-D unit (FAS) because of the belief that a period of initial CPR during lead placement, before rhythm analysis and defibrillation, might be appropriate and beneficial. Personal communications with two other early EMT-D researchers (MS Eisenberg and KR Stults) indicate that their original decision was a "judgment call" based primarily on concerns about monitor artifact.

3. Address the prohibition on attaching AEDs (with or without monitoring screens) to patients not in full arrest as a possible disadvantage, primarily because it potentially delays shock delivery in cases of caregiver-witnessed arrests. It also is the source of continuing confusion over protocols (what is one to do if a pulse is restored-remove the device?) and should be more directly addressed to clarify these questions. [Destro 1996]

4. List the inability to check multiple leads with adhesive dual-function electrodes (used with all AEDs) to rule out false asystole as a disadvantage-or recommend a maneuver to get around this problem. This would resolve the inconsistency in the present guidelines, which recommend checking a second lead with a manual defibrillator but are silent on the issue in relation to AEDs.

One of the first EMT-D programs, in Mercer Island, WA, began in 1973 as a two-tiered response system backed up by a paramedic unit. The initial training course was eight hours, emphasizing arrhythmia analysis and manual defibrillation, with continuing periodic physician-led case review during the subsequent 26 years. The most recent five-year period for which complete data is available showed survival to hospital discharge for patients with witnessed arrest and initial rhythm of VF was 47% (7 of 15). This is comparable to the survival rate of 44% of patients experiencing VF after arrival of paramedics in all of King County, WA (data from King County Emergency Medical Services Division of Seattle-King County Department of Public Health). The ILCOR guideline recommends changing this and other EMT-D programs by having them switch to AEDs. This recommendation is not justified on the basis of present evidence.

Summary

Current AED technology has some clinical disadvantages compared with manual defibrillation: the possible blocking of shocks due to erroneous diagnosis of asystole, the necessity of withholding chest compressions during rhythm analysis, the prohibition on attaching the devices to a patient not in full arrest, and longer times to first shock in some situations. In addition, many healthcare settings (e.g., the majority of hospitals) have manual defibrillators but not AEDs, making AED training irrelevant at present. The AHA and ILCOR should acknowledge these facts and avoid mandating AEDs in settings other than public access defibrillation (PAD), in order to facilitate informed decisions about how best to implement early defibrillation in EMS systems and hospitals.

The AHA and ILCOR may be overselling AED technology by promoting its use to all levels of caregivers, most explicitly in the ILCOR advisory statement "Early Defibrillation," but also in other materials that increasingly treat early defibrillation and AEDs as synonymous. AED technology should not be promoted by these organizations in settings where manual defibrillators are a feasible option unless and until the clinical superiority of AED technology is demonstrated in those settings.

.

Bradley 1988: Bradley K, Sokolow AE, Wright KJ. A comparison of an innovative four-hour EMT-D course with a "standard" ten-hour course. Ann Emerg Med. 1988;17:813-819.

Cummins 1987: Cummins RO, Eisenberg MS, Litwin PE, Graves JR, Hearne TR, Hallstrom AP. Automatic external defibrillators used by emergency medical technicians: a controlled clinical trial. JAMA 1987; 257(12): 1605-1610.

Cummins 1998: Cummins RO, Eisenberg MS, Moore JE, Hearne TR, Andresen E, Wendt R, Litwin PE, Graves JR, Hallstrom AP, Pierce J. Automatic external defibrillators: clinical, training, psychological, and public health issues. Ann Emerg Med 1985 Aug 14;8:755-760.

Destro 1996: Destro A, Marzaloni M, Sermasi S, Rossi F. Automatic external defibrillators in the hospital as well? Resuscitation 1996 Feb 31:1 39-43; discussion 43-4.

Domanovits 1998: Domanovits H. Successful automatic external defibrillator operation by people trained only in basic life support in a simulated cardiac arrest situation. - Resuscitation 1998; 39(1-2): 47-50.

Eisenberg 1984: Eisenberg MS,  Hallstrom AP, Copass MK, Bergner L, Short F, Pierce J. Treatment of ventricular fibrillation: emergency medical technician defibrillation and paramedic services. JAMA. 1984;251:1723-1726.

Eisenberg 1980: Eisenberg MS, Copass MK, Hallstrom AP, Blake B, Bergner L, Short FA, Cobb LA. Treatment of out-of-hospital cardiac arrests with rapid defibrillation by emergency medical technicians. N Engl J Med. 1980;302:1379-1383.

Fromm 1997: Fromm RE Jr, Varon J. Automated external versus blind manual defibrillation by untrained lay rescuers. Resuscitation 1997 Jan 33:3 219-21.

Jerin 1998: Jerin JM, Ansell BA, Larsen MP, Cummins RO. Automated external defibrillators: skill maintenance using computer-assisted learning. Acad Emerg Med 1998 Jul 5:7 709-17.

Kaye 1995: Kaye W, Mancini ME, Giuliano KK, et al. Strengthening the in-hospital chain of survival with rapid defibrillation by first responders using automated external defibrillators: training and retention issues. Ann Emerg Med. 1995;25(2):163-168.

MacKintosh 1979: MacKintosh AF, Crabb ME, Brennan H, Williams J, Chamberlain DA. Hospital resuscitation from ventricular fibrillation in Brighton. Br Med J. 1979;1:511-513.

Mancini 1998: Mancini ME, Kaye W. In-hospital first-responder automated external defibrillation: what critical care practitioners need to know. Am J Crit Care 1998 July 7;4:314-319.

McKee 1994: McKee DR, Wynne G, Evans TR. Student nurses can defibrillate within 90 seconds: an evaluation of a training programme for third year student nurses in the use of an automatic external defibrillator. Resuscitation. 1994;27(1):35-37.

Mols 1994: Mols P, Beaucarne E, Bruyninx J, Labruyere JP, De Myttenaere L, Naeije N, Watteeuw G, Verset D, Flamand JP. Early defibrillation by EMTs: the Brussels experience. Resuscitation 1994 Mar 27;2:129-136.

Sato 1997: Sato Y, Weil MH, Sun S, Tang W, Xie J, Noc M, Bisera J. Adverse effects of interrupting precordial compression during cardiopulmonary resuscitation. Crit Care Med 1997 May 25:5 733-6.

Schneider 1994: Schneider T, Mauer D, Diehl P, Eberle B, Dick W. Quality of on-site performance in prehospital ACLS. Resuscitation 1994; 27: 207-213.

This is a companion article to a report (Schneider T, Mauer D, Diehl P, Dick W, Brehmer F, Juchems R, Kettler D, Kleine-Zander R, Klingler H, Rossi R, et al. Early defibrillation by emergency physicians or emergency medical technicians? A controlled, prospective multi-centre study. Resuscitation 1994 May 27;3 :197-206) of a study comparing outcomes from defibrillation by emergency physicians using manual defibrillators with defibrillation by EMTs using AEDs (shorter response times in the latter group). The outcomes study was excluded because the groups were not equivalent (it found no significant differences in survival), but we have included the companion article because it directly compares some process variables, particularly time interval to first defibrillation, which are directly relevant to the recommendation. More comments above.

Schrading 1993: Schrading WA, Stein S, Eitel DR, Grove L, Horner L, Steckert G, Sabulsky NK, Ogden CS, Hess DR. An evaluation of automated defibrillation and manual defibrillation by emergency medical technicians in a rural setting. Am J Emerg Med 1993 Mar 11:2 125-30.

Stewart JA 1989: Stewart JA. Evaluation of a defibrillation training program far noncritical care nurses. Dallas, Texas: Southwestern Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center at Dallas; 1989. [thesis]

Stewart AJ 1994: Stewart AJ, Martin DL. Knowledge and attitude of nurses on medical wards to defibrillation. J Royal Coll Phys Lond. 1994;28(5):399-401.

Stewart JA 1996: Stewart JA. Delayed in-hospital defibrillation. Ann Emerg Med. 1996; 27(1): 5-6. Also accessible on the Worldwide Web at http://www.defib.net/did.htm.

Stewart JA 1997: Stewart JA. Are AEDs faster than manual defibrillators? Accessible on the Worldwide Web by clicking here.

Stults 1986: Stults KR, Brown DD, Kerber RE. Efficacy of an automated external defibrillator in the management of out-of-hospital cardiac arrest: validation of the diagnostic algorithm and initial clinical experience in a rural environment. Circulation 1986; 73(4) 701-709.

Ten Eyck 1993: Ten Eyck RP. Automated external defibrillator training and skills maintenance in Air Force emergency medical services systems. Mil Med. 1993 Sep 158:9 579-81.

Walters 1992: Walters G, D'Auria D, Glucksman E. Automated external defibrillators: implications for training qualified ambulance staff. Ann Emerg Med. 1992 Jun 21:6 692-7.

Warwick 1995: Warwick JP, Mackie K, Spencer I. Towards early defibrillation--a nurse training programme in the use of automated external defibrillators [see comments] Resuscitation 1995 Dec 30:3 231-35.

Web Pages Created With AOLpress