Introduction: The intracavitary electrocardiographic method is recommended for assessing the location of the tip of central venous catheter when there is an identifiable P wave. Previous reports suggested that intracavitary electrocardiographic method might also be applied to patients with atrial fibrillation, considering the so-called f waves as a surrogate of the P wave. Methods: We studied 18 atrial fibrillation patients requiring simultaneously a central venous catheter and a trans-esophageal echocardiography. An intracavitary electrocardiographic trace was recorded with the catheter tip in three different positions defined by trans-esophageal echocardiography imaging: in the superior vena cava, 2 cm above the cavo-atrial junction; at the cavo-atrial junction; and in the right atrium, 2 cm below the cavo-atrial junction. Three different criteria of measurement of the f wave pattern in the TQ tract were used: the mean height of f waves (method A); the height of the highest f wave (method B); the difference between the highest positive peak and the lowest negative peak (method C). Results: There were no complications. With the tip placed at the cavo-atrial junction, the mean value of the f waves was significantly higher than in the other two positions. All three methods were effective in discriminating the tip position at the cavo-atrial junction, though method B proved to be the most accurate. Conclusion: A modified intracavitary electrocardiographic technique can be safely used for detecting the location of the tip of central venous catheters in atrial fibrillation patients: the highest activity of the f waves is an accurate indicator of the location of the tip at the cavo-atrial junction.

To the Editor, Since Covid-19 outbreak in March 2020, concerns have risen about how to perform ventilation during cardiopulmonary resuscitation (CPR), balancing the need for victim to be resuscitated according to the best evidence with rescuers safety. Indeed, SARS-Cov-2 virus has shown to be highly transmissible via aerosol droplets generated from the airways of an infected person, both symptomatic and not. 1 While for occasional rescuers (i.e. laypeople), chest compression-only (CCO) CPR can be recommended as an alternative to compressionsventilations technique, 2 reasonable suggestions for healthcare professionals are lacking.So far, safety focus for personnel with a duty to respond has been placed on high-level personal protection equipment (PPE) rather than on a method to minimize dispersion of exhaled gases from the patient. Endotracheal intubation (ETI) is still considered the best way to isolate airways provided that it is performed by a high-skilled operator, possibly with a video laryngoscope aid. 3 Recently, an American interim guidance for basic and advanced life support has been published suggesting questionable approaches to obtain oxygenation of the patient in cardiac arrest prior ETI. 4 It is unlikely that both ventilation with a tight seal bag-mask device or passive oxygenation with an oxygen high flow facial mask can effectively constrain exhalation and limit rescuers exposition to patient-generated droplets during CPR.

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