Routine Thoracentesis in Medical ICU Patients with Pleural Effusions

Abstract & Commentary

Synopsis: In ICU patients with a pleural effusion, thoracentesis is a simple and safe procedure that may provide large benefits in diagnosis, treatment, and even prognosis.

Source: Fartoukh M, et al. Clinically documented pleural effusions in medical ICU patients: How useful is routine thoracocentesis? Chest. 2002;121:178-184.

Fartoukh and colleagues carried out a study to assess the contribution of routine thoracentesis to the etiologic diagnosis and treatment in medical ICU patients with clinically documented pleural effusions. All consecutive patients admitted to 3 medical ICUs within a 1-year period were screened prospectively for physical and radiographic evidence of pleural effusion. When a pleural effusion was detected, thoracentesis was performed. Contraindications to thoracentesis included hemodynamic instability, severe respiratory insufficiency (PaO2 < 50 mm Hg on room air), a small effusion, and severe hemostasis alterations (platelets < 50 G/L, fibrinogen < 2 g/L, prothrombin < 50% of control, or cephalin-activated time more than twice the control). Age and sex, comorbidity, reasons for medical ICU admission, and clinical characteristics (day of thoracentesis) were collected. Two senior physicians and 1 junior physician made a presumptive diagnosis. Then, the usefulness of thoracentesis was evaluated separately for diagnosis and the treatment changes.

Of 1351 patients admitted during the study period, 113 patients had physical and radiographic evidence of pleural effusion. Thoracentesis was performed in 82 patients without contraindications to the technique. The mean time from admission to thoracentesis was 2 days (range, 0-6 days). Respiratory failure was the most common reason for medical ICU admission of these patients (median PaO2/FiO2 186 mm Hg), and 60% of them were receiving mechanical ventilation at the time of thoracentesis, 42% requiring positive end-expiratory pressure of 5 cm H2O or more. Pneumothorax occurred in 6 patients (7%), including 5 patients with mechanical ventilation, all with a favorable outcome after drainage. No other complications were reported.

Pleural effusions were classified as transudates or exudates according to Light’s criteria. The causes of pleural effusions are shown in Table 1, below.

Table 1

Causes of Pleural Effusions in Medical ICU Patients

Classification of pleural effusion Patients # (%)  Causes of pleural effusions  #
Transudate   20 (24.4%) Fluid overload 16
    Hypoalbuminemia 4
       

Noninfectious exudate   

27 (32.9%) Malignancy 10
   

Postoperative 

4
   

Hemothorax 

4
   

Pancreatitis 

2
   

Unknown 

3
       
Infectious exudate  35 (42.7%)  Parapneumonic 21
    Empyema  14

The thoracentesis-based diagnosis was different from the presumptive diagnosis in 37 patients (45.1%). Twenty-seven out of 37 patients received a change in treatment based on the findings of thoracentesis. Moreover, 9 patients received a change in treatment attributable to the thoracentesis although their diagnosis remained unchanged. Patients in whom thoracentesis was useful had a trend toward a shorter ICU stay and a lower mortality rate (see Table 2, below). What is more, neither clinical nor laboratory parameters predicted the usefulness of routine thoracentesis in critically ill patients with pleural effusions.

Table 2

Patient Outcomes
in Relation to Thoracentesis Results

 
  Thoracentesis  
  Useful Nonuseful  P
ICU stay (days)* 10 (6-16) 14 (7-23) 0.11
Mortality rate (%) 30 40 0.16
* Medians (quartiles)

Comment by Francisco Baigorri, MD

The same research group previously published a survey of the opinions of French intensivists regarding pleural effusions in ICU patients (Azolulay E, et al. J Crit Care. 2001;16:98-101). In that survey, only 15.5% of the physicians who returned the questionnaire reported that they systematically performed exploratory thoracentesis on the sole basis of the presence of pleural effusion in an ICU patient, irrespective of the clinical context. Notably, in the opinion of these physicians, infection was more frequently listed as a cause of pleural effusions.

The study by Fartoukh et al confirms that infection is the main cause of pleural effusion detected by physical and radiographic findings in this population. Moreover, they claimed that routine thoracentesis provided the correct diagnosis in 8 cases of pleural empyema for which the presumptive cause was a parapneumonic effusion, pulmonary embolism, hemothorax, or surgery. It is obvious to everyone that diagnosing infectious effusions is important to improve the treatment and prognosis as the results of the Fartoukh’s study suggest.

In the survey of the opinions of French intensivists physicians who systematically performed exploratory thoracentesis were more likely to describe the procedure as noninvasive.1 The results of the study we are reviewing also show that thoracentesis is a safe procedure. Moreover, the feasibility and safety of thoracentesis can be even higher when aided by ultrasound.2 No complications were reported in mechanically ventilated patients when thoracentesis was performed assisted by ultrasound.

Thus, there is no big argument against routine thoracentesis in medical ICU patients with clinically documented pleural effusions. It remains to be seen whether this recommendation might be applied to small effusions only detected by using other diagnostic tools such as ultrasound or CT. Nevertheless, as Fartoukh et al say, there are no data to suggest that small effusions detected by ultrasound are qualitatively different from those detected clinically.

Dr. Baigorri is Corporacio Sanitaria, Parc Tauli, Sabadell, Spain.

References

1. Azolulay E, et al. J Crit Care. 2001;16:98-101.

2. Lichtenstein D, et al. Intensive Care Med. 1999;25: 955-958.