The "lung point": an ultrasound sign specific to pneumothorax.

OBJECTIVE: We studied an ultrasound sign, the fleeting appearance of a lung pattern (lung sliding or pathologic comet-tail artifacts) replacing a pneumothorax pattern (absent lung sliding plus exclusive horizontal lines) in a particular location of the chest wall. This sign was called the "lung point".

DESIGN: Prospective study.

SETTING: The medical ICU of a university-affiliated teaching hospital.

PATIENTS: The "lung point" was sought in 66 consecutive cases of proven pneumothorax analyzable using ultrasound--including 8 radio-occult cases diagnosed by means of CT and in 233 consecutive hemithoraces studied by CT and free of pneumothorax-- including 17 cases where pneumothorax was suspected.

RESULTS: The "lung point" was observed in 44 of 66 cases of pneumothorax (including 6 of 8 radio-occult cases) and in no case in the control group. The location of this sign roughly correlated with the radiological size of the pneumothorax. The "lung point" therefore had an overall sensitivity of 66 % (75 % in the case of radio-occult pneumothorax alone) and a specificity of 100%.

CONCLUSION: The presence of a "lung point" allows positive diagnosis of pneumothorax at the bedside using ultrasound.