Safe and effective bedside thoracentesis: A review of the evidence for practicing clinicians

The PubMed search returned a total of 1170 manuscripts, of which 56 articles met inclusion criteria. Four additional articles were identified by experts and included in the study.^4-7 Therefore, 60 articles were identified and included in this review. Study designs included cohort studies, case control studies, systematic reviews, meta-analyses, narrative reviews, consensus guidelines, and randomized controlled trials. A summary of all included articles by topic can be found in the Table.
 

PRE-PROCEDURAL CONSIDERATIONS

Physician Training

Studies indicate that graduate medical education may not adequately prepare clinicians to perform thoracentesis.⁸ In fact, residents have the least exposure and confidence in performing thoracentesis when compared to other bedside procedures.^9,10 In 1 survey, 69% of medical trainees desired more exposure to procedures, and 98% felt that procedural skills were important to master.¹¹ Not surprisingly, then, graduating internal medicine residents perform poorly when assessed on a thoracentesis simulator.¹²

Supplemental training outside of residency is useful to develop and maintain skills for thoracentesis, such as simulation with direct observation in a zero-risk environment. In 1 study, “simulation-based mastery learning” combined an educational video presentation with repeated, deliberate practice on a simulator until procedural competence was acquired, over two 2-hour sessions. In this study, 40 third-year medicine residents demonstrated a 71% improvement in clinical skills performance after course completion, with 93% achieving a passing score. The remaining 7% also achieved passing scores with extra practice time.¹² Others have built upon the concept of simulation-based training. For instance, 2 studies suggest that use of a simulation-based curriculum improved both thoracentesis knowledge and performance skills in a 3-hour session.^13,14 Similarly, 1 prospective study reported that a half-day thoracentesis workshop using simulation and 1:1 direct observation successfully lowered pneumothorax rates from 8.6% to 1.8% in a group of practicing clinicians. Notably, additional interventions including use of bedside US, limiting operators to a focused group, and standardization of equipment were also a part of this quality improvement initiative.⁷ Although repetition is required to gain proficiency when using a simulator, performance and confidence appear to plateau with only 4 simulator trials. In medical students, improvements derived through simulator-based teaching were sustained when retested 6 months following training.¹⁵

An instrument to ensure competency is necessary, given variability in procedural experience among both new graduates and practicing physicians,. Our search did not identify any clinically validated tools that adequately assessed thoracentesis performance. However, some have been proposed¹⁶ and 1 validated in a simulation environment.¹² Regarding the incorporation of US for effusion markup, 1 validated tool used an 11-domain assessment covering knowledge of US machine manipulation, recognition of images with common pleural effusion characteristics, and performance of thoracic US with puncture-site marking on a simulator. When used on 22 participants, scores with the tool could reliably differentiate between novice, intermediate, and advanced groups (P < 0.0001).¹⁷

Patient Selection

Coagulopathies and Anticoagulation. Historically, the accepted cutoff for performing thoracentesis is an international normalized ratio (INR) less than 1.5 and a platelet count greater than 50,000/µL. McVay et al.¹⁸ first showed in 1991 that use of these cutoffs was associated with low rates of periprocedural bleeding, leading to endorsement in the British Thoracic Society (BTS) Pleural Disease Guideline 2010.¹⁹ Other recommendations include the 2012 Society for Interventional Radiology guidelines that endorse correction of an INR greater than 2, or platelets less than 50,000/µL, based almost exclusively on expert opinion.⁵

However, data suggest that thoracentesis may be safely performed outside these parameters. For instance, a prospective study of approximately 9000 thoracenteses over 12 years found that patients with an INR of 1.5-2.9 or platelets of 20,000 - 49,000/µL experienced rates of bleeding complications similar to those with normal values.²⁰ Similarly, a 2014 review²¹ found that the overall risk of hemorrhage during thoracentesis in the setting of moderate coagulopathy (defined as an INR of 1.5 - 3 or platelets of 25,000-50,000/µL), was not increased. In 1 retrospective study of more than 1000 procedures, no differences in hemorrhagic events were noted in patients with bleeding diatheses that received prophylactic fresh frozen plasma or platelets vs. those who did not.²² Of note, included studies used a variety of criteria to define a hemorrhagic complication, which included: an isolated 2 g/dL or more decrement in hemoglobin, presence of bloody fluid on repeat tap with associated hemoglobin decrement, rapid re-accumulation of fluid with a hemoglobin decrement, or transfusion of 2 units or more of whole blood.

Whether it is safe to perform thoracentesis on patients taking antiplatelet therapy is less well understood. Although data are limited, a few small-scale studies^23,24 suggest that hemorrhagic complications following thoracentesis in patients receiving clopidogrel are comparable to the general population. We found no compelling data regarding the safety of thoracentesis in the setting of direct oral anticoagulants, heparin, low-molecular weight heparin, or intravenous direct thrombin inhibitors. Current practice is to generally avoid thoracentesis while these therapeutic anticoagulants are used.

Invasive mechanical ventilation. Pleural effusion is common in patients in the intensive care unit, including those requiring mechanical ventilation.²⁵ Thoracentesis in this population is clinically important: fluid analysis in 1 study was shown to aid the diagnosis in 45% of cases and changes in treatment in 33%.²⁶ However, clinicians may be reluctant to perform thoracentesis on patients who require mechanical ventilation, given the perception of a greater risk of pneumothorax from positive pressure ventilation.

Despite this concern, a 2011 meta-analysis including 19 studies and more than 1100 patients revealed rates of pneumothorax and hemothorax comparable to nonventilated patients.²⁵ Furthermore, a 2015 prospective study that examined thoracentesis in 1377 mechanically ventilated patients revealed no difference in complication rates as well.²⁰ Therefore, evidence suggests that performance of thoracentesis in mechanically ventilated patients is not contraindicated.