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. 2001 Nov 3;323(7320):1065.

Doctors' positioning of defibrillation paddles

Level of evidence should have been assessed

J Calinas-Correia 1
PMCID: PMC1121556  PMID: 11713739

Editor—Heames et al assessed the performance of doctors in placing defibrillation paddles in the correct positions on the chest of a training manikin.1 They forgot to assess the level of evidence that allows for the determination of correct placement. Volume 46 of Resuscitation presents only two references about paddle placement: one is the original work by Lown in 1967, the other a 1981 study by Kerber et al.2–4 The text in Resuscitation is almost word for word that of the American Heart Association's guidelines published in 1992 in the journal of the American Medical Association, which offered the same paucity of references.5

I conclude that the evidence on which Heames et al base their assessment is the original work done in 1967 and the comparison made by Kerber et al. The work in 1967 was done with quite different equipment, timings between shocks, and wave forms. The comparison by Kerber et al was between anterolateral and anteroposterior placement, with only one version of either except for the pad's diameter, and exclusively addressed the cardioversion of atrial fibrillation.

So far as the references quoted go, there is no evidence that the variation detected by the study is of any clinical importance.

References

  • 1.Heames RM, Sado D, Deakin CD. Do doctors position defibrillator paddles correctly? Observational study. BMJ. 2001;322:1393–1394. doi: 10.1136/bmj.322.7299.1393. . (9 June.) [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Part 4: the automated external defibrillator: key link in the chain of survival. Resuscitation. 2000;46:73–91. doi: 10.1016/s0300-9572(00)00272-0. [DOI] [PubMed] [Google Scholar]
  • 3.Part 6: advanced cardiovascular life support. Section 2: defibrillation. Resuscitation. 2000;46:109–113. [PubMed] [Google Scholar]
  • 4.Kerber RE, Jensen SR, Grayzel J, Kennedy J, Hoyt R. Elective cardioversion: influence of paddle-electrode location and size on success rates and energy requirements. N Engl J Med. 1981;305:658–662. doi: 10.1056/NEJM198109173051202. [DOI] [PubMed] [Google Scholar]
  • 5.Emergency Cardiac Care Committee and Subcommittees, American Heart Association. Guidelines for cardiopulmonary resuscitation and emergency cardiac care. Part IX. Ensuring effectiveness of communitywide emergency cardiac care. JAMA. 1992;268:2289–2295. [PubMed] [Google Scholar]
BMJ. 2001 Nov 3;323(7320):1065.

Other factors have not been assessed

R Khiani 1

Editor—Heames et al report a study of 101 doctors who were asked to place the paddles on a manikin who they were told was in ventricular fibrillation.1-1 The doctors placed the sternal and apical paddles incorrectly in 35% and 78% of cases, respectively.

This study has not targeted the health professionals who perform defibrillation in clinical settings. Trained nurses and paramedics are commonly called on to perform defibrillation, but neither of these groups was investigated. Twenty per cent of the study group included consultants, who rarely carry out defibrillation. No details were given of whether the doctors enrolled formed a part of the hospital's cardiac arrest team, which commonly performs defibrillation.

Heames et al ask whether doctors position the paddles for defibrillation correctly. Their assumption is that incorrect paddle placement reduces the chances of successful defibrillation. This study defined incorrect paddle placement as more than 5 cm from the position stated by the guidelines issued by the European Resuscitation Council. This is an arbitrary distance, as the distance of incorrect paddle placement that results in unsuccessful defibrillation is unknown. In addition, there is no hard evidence that incorrect paddle placement is an important cause of reduced survival in patients with ventricular fibrillation. There is, however, evidence that several other factors do affect survival of patients in ventricular fibrillation. In cardiac arrests occurring out of hospital, cardiopulmonary resuscitation through bystanders, and shorter ambulance response times, strongly predict survival to hospital discharge.1-2 Other initiatives such as the provision of intelligent defibrillators in public places may also be important.

In hospital the use of monitored beds in coronary care units improves survival in cardiac patients, mainly by reducing the time to defibrillation. Although the provision of defibrillators on each ward, the level of staff training, and the response time of the “crash team” are also likely to be important, more research is needed into these subjects.

The study by Heames et al is a small, observational study in an artificial setting using a manikin and an unrepresentative group of health professionals. The question of whether incorrect paddle position is a cause of unsuccessful defibrillation of patients in ventricular fibrillation remains unanswered. Other factors that are more likely to be important in outcome for such patients have not been addressed.

References

  • 1-1.Heames RM, Sado D, Deakin CD. Do doctors position defibrillator paddles correctly? Observational study. BMJ. 2001;322:1393–1394. doi: 10.1136/bmj.322.7299.1393. . (9 June.) [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 1-2.Pell JP, Sirel JM, Marsden AK, Ford I, Cobbe SM. Effect of reducing ambulance response times on deaths from out of hospital cardiac arrest. BMJ. 2001;322:1385–1388. doi: 10.1136/bmj.322.7299.1385. . (9 June.) [DOI] [PMC free article] [PubMed] [Google Scholar]
BMJ. 2001 Nov 3;323(7320):1065.

Authors' reply

Richard M Heames 1, Daniel M Sado 1, Charles D Deakin 1

Editor—The current recommendations for paddle position during defibrillation emanate from the International Liaison Committee on Resuscitation (ILCOR).2-1 The evidence for these recommendations is based on limited human and animal studies and physiological modelling but represents what is considered an optimal position. Contrary to Calinas-Correia's assertions, there is plenty of evidence that misplaced paddles are of clinical significance. Calinas-Correia overlooks the aim of our study, which was to assess whether defibrillation guidelines are followed—it was not to provide a review of the evidence for the guidelines, which has recently been carried out by ILCOR.2-1

In hospital all doctors participating in clinical practice are expected to be able to perform basic life support, including defibrillation. Whether they are members of the cardiac arrest team or not does not excuse them from their ability to defibrillate correctly. Khiani's statement that consultants rarely carry out defibrillation is not evidence based and certainly does not apply to the centre in which this study was carried out.

Paramedics do not, and nurses rarely defibrillate patients in our hospital. Defibrillation should be performed by the first competent person to reach the patient, whether he or she is a member of the cardiac arrest team or not. All doctors in acute medical and surgical specialties were therefore studied as it is this group that is likely to be performing defibrillation. Khiani says that it is still unclear from this study whether the issue of incorrect paddle placement is a notable problem among staff who perform defibrillation in clinical settings, be they doctors, nurses, or paramedics. We disagree, having studied a group representative of those performing defibrillation in a typical hospital.

We stated that incorrect paddle placement results in a greater proportion of the current passing through non-cardiac tissue and a reduced chance of successful defibrillation. Khiani challenges this, saying that these assumptions have yet to be proved and their effect on survival to hospital discharge is unknown. He is unaware of studies showing that adjacent placement of electrodes creates a low impedance pathway along the chest wall, which shunts current away from the heart and may result in failed defibrillation,2-2 confirmed by finite element analysis.2-3 Paddle position is an important determinant of the success of cardioversion for atrial fibrillation,2-4–2-6 and although optimal paddle position may not be the same as that for ventricular fibrillation, it does suggest that paddle position is of equal importance in determining the success of defibrillation for ventricular fibrillation.

We agree with Khiani about the importance of cardiopulmonary resuscitation through bystanders, shorter ambulance response times, and the provision of advisory defibrillators in public places, but these factors are not relevant to our study. We do not agree that a survey of 101 doctors is “small” in the context of this study. The use of a manikin has produced results similar to those that we have observed during actual cardioversion. The aim of the study was to assess whether doctors position defibrillation paddles correctly. Our study aims have been met.

References

  • 2-1.Part 6: Advanced cardiovascular life support. Section 2: defibrillation. Resuscitation. 2000;46:109–113. [PubMed] [Google Scholar]
  • 2-2.Catherine MR, Yoerger DM, Spencer KT, Kerber RE. Effect of electrode position and gel-application technique on predicted transcardiac current during transthoracic defibrillation. Ann Emerg Med. 1997;29:588–595. doi: 10.1016/s0196-0644(97)70245-2. [DOI] [PubMed] [Google Scholar]
  • 2-3.Jorgenson DB, Haynor DR, Bardy GH, Kim Y. Computational studies of transthoracic and transvenous defibrillation in a detailed 3-D human thorax model. IEEE Trans Biomed Eng. 1995;42:172–184. doi: 10.1109/10.341830. [DOI] [PubMed] [Google Scholar]
  • 2-4.Ewy GA. The optimal technique for electrical cardioversion of atrial fibrillation. Clin Cardiol. 1994;17:79–84. doi: 10.1002/clc.4960170207. [DOI] [PubMed] [Google Scholar]
  • 2-5.Botto GL, Politi A, Bonini W, Broffoni T, Bonatti R. External cardioversion of atrial fibrillation: role of paddle position on technical efficacy and energy requirements. Heart. 1999;82:726–730. doi: 10.1136/hrt.82.6.726. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2-6.Mehdirad AA, Clem KL, Love CJ, Nelson SD, Schaal SF. Improved clinical efficiency of external cardioversion by fluoroscopic electrode positioning and comparison to internal cardioversion in patients with atrial fibrillation. Pacing Clin Electrophysiol. 1999;22:233–237. doi: 10.1111/j.1540-8159.1999.tb00339.x. [DOI] [PubMed] [Google Scholar]

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