The presence of air or another gas in the pleural space.

Observation of the following triad suggests the need for exclusion of pneumothorax

  Isolated low voltage in lead I

  Poor R wave progression in chest leads

  Lead aVF
/Lead I QRS amplitude ratio is > 2

The following ECG abnormalities may be observed in pneumothorax
the first four are the most common)

  Right axis deviation (especially in left-sided pneumothorax)

  Decreased amplitude of R wave in chest leads

  Negative T waves in chest leads

  Decreased QRS amplitude (low voltage)

  ST segment elevation

  ST segment depression

  QS in leads V1-V4

  Decreased amplitude of the P, QRS and T waves in lead I (
especially in right-sided pneumothorax)

  Extreme phasic respiratory variations in R wave amplitude

The abnormal ECG findings are expected to disappear after decompression of the pneumothorax.

Pneumothorax, ECG and the recording position

  In patients with pneumothorax, it has been reported that most of the ECG abnormalities detected during

      supine ECG disappear when the ECG is recorded in the erect posture.


  Heart & Lung 2011;40:88-91.

  Am J Med Sci 1946;212:682-690.

  Arch Intern Med 1970;125:151-153.

  Chest 1984;86:143-145.

  Int J Cardiol 2011;153:78-80.

  Resuscitation 2002;52:306-307.

  Chest 1999;115:1742-1744.

  J Electrocardiology 1997;30:109-111.

  Am J Emerg Med 2008;26:959-962.

  J Emerg Med. 2014 Jan 16. pii: S0736-4679(13)01128-1. doi: 10.1016/j.jemermed.2013.09.016.

  Comprehensive Electrocardiology. Peter W. Macfarlane. 2nd ed. Springer-Verlag London 2011.

ECG 1a. The above ECG is from a 36 years-old woman with left pneumothorax.It was recored just before chest tube placement.
She was diagnosed as breast cancer 2 months ago after which she underwent right mastectomy.
Loss of R wave progression in chest leads is seen.
The ECG machine commented "possible anterolateral infarct - age undetermined".
However, this is a false diagnosis since she had no previous myocardial infarction (ECHOcardiography showed
normal left ventricular wall motion).
Low voltage in leads I and V6 should raise the suspicion of left pneumothorax.
There is also right axis deviation (QRS axis is 102 degrees).

Dr. Mehmet Serdar Yildirim has donated the above ECG to our website.

Click here for a more detailed ECG

ECG 1b. Above is her ECG. It was recorded 2 days after chest tube placement.
R wave progression in anterior leads is better now.
QRS amplitudes in leads I and V6 are increased.
Right axis deviation is not seen anymore. Now
the QRS axis is normal (81 degrees).

Dr. Mehmet Serdar Yildirim has donated the above ECG to our website.

Click here for a more detailed ECG