Pleural Manometry for the Characterization of Spontaneous and Tension Pneumothorax

The rate of hospitalization for spontaneous pneumothorax among people age 14 or older is approximately 227 per million. Spontaneous pneumothorax in the absence of trauma can be further classified as primary spontaneous pneumothorax (PSP) or secondary spontaneous pneumothorax (SSP) based on the absence or presence of underlying structural lung disease, respectively. Though recent studies suggest that in some cases conservative management with close observation is an acceptable treatment, definitive evacuation remains a cornerstone of management for patients who are symptomatic or who have a large pneumothorax. Intrapleural air can be removed by either needle aspiration or introduction of a watersealed catheter into the pleural space. In the event of tension pneumothorax (TP), emergent chest thoracostomy is preferred. In all cases, the goal of treatment remains to re-expand the affected lung, after which the catheter may be removed. If the visceral pleural defect is not healed after 5 days, it is deemed a persistent air leak. In these cases, the chest tube is maintained and more aggressive measures such as pleurodesis, placement of an intrabronchial valve (IBV), or VATS are performed. Unfortunately, there is currently no method to predict which patients will require these more invasive procedures.

The lack of prognostic indicators is not the case in pleural effusions, however. Pleural manometry has been shown to be a useful tool in the management of patients with effusions. Doelken et al. described using an overdamped water manometer or an electronic transducer connected to a thoracentesis catheter for the direct measurement of Ppl with similar accuracy. Traditionally, thoracenteses are aborted after onset of dyspnea or cough, all fluid is drained, or 1 liter of fluid has been removed. This 1 liter limit exists to avoid the feared complicated of reexpansion pulmonary edema. However, monitoring of Ppl during drainage and aborting the procedure once Ppl drops below -20 cmH2O allows for safe drainage of often larger volumes. - Furthermore, it has been demonstrated that Ppl could diagnose non-expandable lung and predict pleurodesis failure in patients with malignant effusion. We recently reported the use of a simple, in-line, digital manometer to measure Ppl in patients with pleural effusion.

Routine use of pleural manometry in the evaluation and management of pneumothorax has not yet been adopted, likely due to the historical difficulty in obtaining measurements and the uncertain clinical benefit pleural manometry provided. It has been found that Ppl in spontaneous pneumothorax was greater in patients that required prolonged drainage. These results were later supported in a study that demonstrated the practicality of measuring Ppl in pneumothorax. Ppl measurements required only up to 30 seconds by using an electronic manometer connected to an intrapleural catheter. Still to date, Ppl in TP have yet to be reported. Ultimately, measurement of Ppl in pneumothorax may help identify patients at increased risk for the need of advanced therapies such as IBV placement, pleurodesis, or VATS. Early identification of these high-risk patients will allow for these interventions to be performed earlier, thus reducing hospital length of stay, associated complications, and health-care costs.

• Study Procedures

• Patients admitted to the Johns Hopkins Hospital with spontaneous, iatrogenic, or tension pneumothorax referred to the Division of Interventional Pulmonology for thoracostomy will be recruited. Using standard sterile technique, a 14fr catheter will be inserted into the pleural space. An electronic manometer (Compass, Medline Industries, Inc.) will be connected in-line to the introducer needle and Ppl will be recorded for 3-5 respiratory cycles. After measurement, the manometer will be removed and the catheter will remain in place per routine standards of practice. Outcome data of patients will be collected including duration of chest tube placement, need for pleurodesis, IBV, and referral for VATS. Patient data will be de-identified and stored on the a Johns Hopkins secured (SAFE) desktop. A separate file will also be kept on the SAFE desktop that contains participant Medical Record Numbers to allow for matching of Ppl measurements with clinical outcomes. Once outcome data is collected for a participant, the participant's identifiable information will be removed. A combined waiver of consent and oral consent process will be used. The waiver of consent will allow performance of chest tube placement and the collection of pressure measurements via the manometer without the consent of potential subjects. Subsequently, an oral consent process will be used to invite potential subjects to enroll in the study and to get consent for the use of the pressure data already collected as well as for further data collection from the patients' medical records.
• No biospecimens will be collected.
• Patients will be enrolled over the course of 1 year. The study will not impact length of hospitalization.
• This is a nonblinded study.
• Patients will continue to receive standard of care treatments. This study may delay catheter placement by mere seconds to accommodate for Ppl measurements, this delay is negligible and
• will not impact clinical outcomes as even in the case of tension the pleural air will be evacuated via the introducer needle.
• This study does not include a placebo group.
• Participant removal criteria include pneumothorax in which Ppl cannot be reliably measured within 30 seconds.
• Participants removed from the study will continue to receive standard-of-care treatment.

Inclusion criteria

• patients aged 18 or older admitted to the Johns Hopkins Hospital with clinical or radiographic evidence of new pneumothorax who are referred to Interventional Pulmonology for needle aspiration or tube thoracostomy. TP will be defined as a pneumothorax that results in mean arterial pressure <65 or systolic BP < 90.

Exclusion criteria

• bilateral pneumothorax