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Volume 5 Supplement 8

18th Spring Meeting of the Association of Cardiothoracic Anaesthetists

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What is the optimal paddle force for defibrillation?


Firm paddle pressure during defibrillation is important to minimize transthoracic impedance (TTI) and optimize trans-myocardial current. Previous European Resuscitation Council (ERC) guidelines recommended that 12 kg force should be used [1] and the more recent International Liaison Committee on Resuscitation (ILCOR) guidelines recommend 'firm' pressure [2]. The actual relationship between force and transthoracic impedance has not been established.


55 patients (36 male, 19 female) undergoing general anaesthesia for cardiac surgery were investigated. Male chests were shaved. A pair of gel pads and paddles were placed in the anterior-apical position according to the ILCOR guidelines. The endotracheal tube was opened to air and paddles instrumented with force sensors were applied to the chest wall with progressive force to a maximum of 12 kgf. The resultant TTI was recorded at 10 measurements per second to a hard drive.


Light pressure results in a high TTI that rapidly decreases as paddle force increases (Fig. 1). An 18.7% fall in overall TTI occurs when applying force from 0.5 to 6.0 kg. Increasing paddle force from 6 to 12 kg results in a further decrease in TTI of 3.2%.

Figure 1
figure 1

The relationship between force and mean TTI for 55 patients.


A minimum of 6 kg force applied to each paddle is necessary to achieve 83% of the overall decrease in TTI seen at 12 kgf. Further decrease in TTI as force is applied in excess of 6 kgf is small and a force of 12 kgf only reduces TTI by a further 3.2% compared with TTI at 6 kgf. The additional clinical benefit of applying 12 kgf as opposed to 6 kgf is questionable.


  1. Robertson C, et al.: Resuscitation 1998, 37: 81. 10.1016/S0300-9572(98)00035-5

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  2. Deakin C, Petley G, Cardan E, Clewlow F: Does paddle force applied during defibrillation meet advanced life support guidelines of the European Resuscitation Council? Resuscitation 2001, 48: 301-303. 10.1016/S0300-9572(00)00265-3

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Deakin, C., Sado, D., Petley, G. et al. What is the optimal paddle force for defibrillation?. Crit Care 5 (Suppl 8), 4 (2001).

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