Therapeutic uses of medical thoracoscopy

INTRODUCTION

Thoracoscopy involves a percutaneous approach to placement of an endoscopic instrument within the pleural space, allowing direct visualization and sampling of the pleura. Unlike video-assisted thoracic surgery (VATS), in which the surgeon uses a thoracoscope to assist with performance of minimally invasive surgery, the purpose of "medical thoracoscopy" is to provide access to the pleura and the pleural space for evaluation and, in some cases, management of pleural disease.

This topic will review the therapeutic uses of medical thoracoscopy. An overview of thoracoscopy and the diagnostic indications for thoracoscopy are discussed separately. (See "An overview of medical thoracoscopy" and "Indications for diagnostic thoracoscopy".)

PLEURAL EFFUSION

The most widely employed therapy for treatment of malignant pleural effusion or recurrent benign pleural effusion involves drainage by tube thoracostomy followed by instillation of sclerosing agents to achieve chemical pleurodesis. Numerous sclerosing agents have been used to induce pleurodesis including talc, tetracycline, minocycline, doxycycline, silver nitrate, iodopovidone, bleomycin, Corynebacterium parvum with parenteral methylprednisolone acetate, erythromycin, fluorouracil, interferon beta, mitomycin C, cisplatin, cytarabine, doxorubicin, etoposide, and Streptococcus pyogenes A3 [1-6]. Chemical pleurodesis is discussed in general separately. (See "Chemical pleurodesis" and "Talc pleurodesis".) This section focuses on the use of thoracoscopic talc poudrage (ie, insufflation) to achieve pleurodesis.

Efficacy — Requirements for successful pleurodesis include even distribution of the sclerosing agent over all pleural surfaces and expansion of the lung to the chest wall. Pleurodesis may fail if there is uneven distribution of agents, if the lung cannot re-expand following fluid removal, or if there is a large tumor burden with a low pleural pH [7]. In theory, thoracoscopic talc poudrage (ie, insufflation) may increase the likelihood of successful pleurodesis in difficult cases by improving talc distribution over the pleural surfaces. This is supported by a series of 25 patients who had malignant effusions with a pH <7.30, which found that 22 patients (88 percent) had successful pleurodesis via thoracoscopic talc poudrage.

Historically, use of talc in its powder form for pleurodesis required a thoracotomy and had reported success rates greater than 90 percent accompanied by operative mortality of approximately two percent. However, talc pleurodesis has since been shown to be equally effective when used in conjunction with thoracoscopy, but with lower morbidity and mortality rates. As an example, one study achieved successful pleurodesis with talc via thoracoscopy in 90 percent, with a mortality rate of only 0.25 percent [8]. Other studies have similarly reported a pleurodesis success rate greater than 90 percent [9]. (See "Talc pleurodesis", section on 'Indications and efficacy'.)

Encouraging results with talc have not been universal. A case series of 611 patients who underwent VATS-directed talc pleurodesis for a pleural effusion over a period of 10 years reported a success rate of only 69 percent, defined as a fully expanded lung at the end of the procedure and no recurrence of the effusion at long-term follow up [10]. The 30-day mortality was 17 percent, higher than that reported in most series. Risk factors for unsuccessful pleurodesis included previous thoracic irradiation and a chest tube duration >10 days, while risk factors for death included a Karnofsky index <50 percent, a body mass index <25 kg/m2, malignancy, and male gender. Several reasons were proposed for the low success rate compared to prior reports, including the large number of unselected cases, the strict definition of successful pleurodesis, and the large number of patients who had a Karnofsky Index ≤60 percent (a risk factor for unsuccessful pleurodesis).

Talc has been compared with other agents for pleurodesis. A randomized trial comparing bleomycin to talc reported a 33 percent failure rate with bleomycin and no failures with talc after a mean follow-up of nine months [11]. Similarly, when tetracycline was compared with talc, the success rates were 48 percent and 92 percent, respectively [12]. In a meta-analysis of 10 randomized trials (308 patients) that compared pleurodesis using talc to pleurodesis using bleomycin, tetracycline, mustine, or chest tube drainage alone, non-recurrence of the pleural effusion was more likely following talc, compared to the alternative agents (RR 1.34, 95% CI 1.04-1.38) [13].

It is uncertain whether the technique for administering talc affects the outcome. In the meta-analysis described above, non-recurrence of the effusion was more likely following thoracoscopic insufflation of talc, compared to bedside instillation of talc slurry through a chest tube (RR 1.19, CI 95% 1.04-1.36) [13]. In contrast, a multicenter trial that randomly assigned 482 patients to either thoracoscopic insufflation of talc or bedside tube instillation of talc slurry demonstrated equal efficacy at 30 days (78 versus 71 percent) [14]. (See "Talc pleurodesis", section on 'Talc insufflation or talc slurry?'.)