The goal of this study is to assess the clinical feasibility of a novel, reusable, low cost gas analyzer that detects breath in chest drains in order to diagnose and heal air leaks. The investigators have developed prototype gas analyzers that attach to the outlet of any analog chest drain, and can be connected temporarily to the sampling port. They detect breath by measuring CO2, O2, and pressure, in order to supplement the information provided by the bubbles in the water seal.

Tests on patients in 2013 at Northwestern demonstrated that gas analysis can help diagnose and heal air leaks by detecting breath in chest drains, as documented in the investigator's patents and peer-reviewed publications. CO2 is 100 times higher in the lung than ambient, and O2 the same amount lower in ppm. The length of time that it takes to detect breath at the outlet is related to the size of the air leak. O2 is available next to every bed, often used in recovery, and when high O2 is quickly detected at the sampling port, the only source can be an active air leak.

The primary aim is to assess whether the device can accurately measure changes in gas flow from an analog pleural drain and whether this accurately detects pleural air leaks.

Specific aim 1: To determine whether the gas analyzer device can measure changes in exhaled gas levels and if this can distinguish true air leaks from false air leaks.

Sub aim 1: Assess how patient characteristics such as extent of resection, pre-existing conditions such as COD, lung function test, etc, affect the efficacy of the device.

Specific aim 2: Compare the accuracy of pleural air leak measured via gas analysis to the accuracy of pleural air leak detection as measured by standard VI.

The hypothesis is that the prototype pleural gas analyzer, through detection of carbon dioxide and oxygen levels, can distinguish true air leaks from false air leaks more accurately than the traditionally practiced method of Visual Inspection of bubbles in the chest drainage unit (VI).

Study Endpoints:

The primary end point of this study is detection of air leak, either by VI or prototype pleural gas analysis.

True Air Leak Definition:

1. Both visual inspection and pleural gas analysis demonstrate an air leak
2. Development of a pneumothorax at any point up to 4 weeks after chest tube removal
3. Pneumothorax develops during a clamp trial to assess for true air leak (failed clamp trial)
4. Patient discharged home with chest tube due to clinical concern (even in absence of clamp trial) of ongoing air leak
5. Development of clinically significant subcutaneous emphysema either with a chest tube in place or after chest tube removal (defined as an increase beyond initial post op, observable to patient or care team) Secondary endpoint is comparison in accuracy in detection of air leak between VI and gas analysis.

Inclusion Criteria:

1. Patients who are scheduled for thoracic surgery and expected to have chest tube placed
2. For patients who are unable to sign consent, but meet all of the inclusion criteria and none of the exclusion criteria, a legally appointed representative (LAR) will be allowed to sign consent for that patient
3. Patients that provide informed consent for the study
4. Patients >18 years old

Exclusion Criteria:

1. Patients with hemodynamic instability
2. Pregnant patients
3. Prisoners
4. Individuals who are not yet adults