Pleural space drainage using small-bore chest tubes inserted under ultrasound (US) guidance has gained increased acceptance in recent years and in many institutions it has replaced large-bore chest tubes for most indications.1 Several studies have demonstrated the safety and efficacy of US-guided small-bore chest tubes with a reported rate of minor bleeding between 1% and 2%.2,3 This data on bleeding complications, however, is primarily on patients without significant coagulopathy and who are not receiving antiplatelet therapy. Not surprisingly, given the current widespread use of antiplatelet agents, pulmonologists are now encountering patients on this therapy who clinically require urgent pleural drainage for either large pleural effusion or occasionally pneumothorax.
Clopidogrel, a thienopyridine compound that profoundly inhibits adenosine diphosphate-induced platelet aggregation,4 is of particular concern. Its efficacy to prevent thrombosis in patients with acute coronary syndromes and coronary artery stents is well established,5,6 but its presence clearly increases the risk of bleeding from surgical procedures. Reflecting the risk of bleeding, a common practice is to discontinue clopidogrel for 5 to 7 days before any invasive procedure. This approach, however, is problematic in patients with an urgent need for pleural space drainage and in patients who have a strong contraindication to stopping clopidogrel (eg, patients with recent placement of coronary stents where the discontinuation has been associated with high risk of thrombosis).7
It has become our practice to proceed with the insertion of a small-bore chest tube under US guidance in patients on clopidogrel when it either cannot be safely stopped or when it is not clinically feasible to wait 5 to 7 days before draining the pleural space. The purpose of this study is to report our experience on the safety of this approach in patients on clopidogrel.
PATIENTS AND METHODS
The study was approved by the Institutional Review Board and was designed as a retrospective review.
A review of the medical records of patients that underwent small-bore chest tube insertion under US guidance by the Pulmonary and Critical Care Division at Cooper University Hospital from January 2010 to September 2012 was carried out. Patients were included in the study if they were at least 18 years old and were taking clopidogrel for at least 5 days and up to 24 hours before the procedure. Data collected included patient’s age, sex, weight, height, serum creatinine, platelet count and coagulation studies, preprocedure and postprocedure hemoglobin, indications for the procedure and for clopidogrel, volume, and underlying cause of effusion and bleeding complications including the need for postprocedure transfusion.
US-guided Chest Tube Insertion
At our institution the insertion of small-bore chest tubes under US guidance is usually performed by a Pulmonary and Critical Care fellow under the direct supervision of an interventional pulmonologist. Our standard procedure is to first evaluate the chest with US (Sonosite M-turbo) with a Phased Array transducer (Sonosite P21X/5-1MHZ) identifying the diaphragm, the effusion, and the pleural line in case of a pneumothorax. The insertion site is identified and marked as close as possible to the posterior axillary line in patients with effusions and in the second intercostal space at the midclavicular line for pneumothorax. Doppler studies of the intercostal arteries are not routinely performed. The site is then prepared, draped, and local anesthesia with 1% lidocaine is administered. A small incision is made using a number 11 scalpel. The catheter is inserted using either a standard Seldinger technique (over a guidewire) or a modified Seldinger (over a needle), depending on the size of tube utilized. Three different catheters were used based on operator preference: 8 Fr Arrow catheter (Arrow International, Reading, PA), 14 Fr Wane pigtail catheter (Cook Medical, Bloomington, IN), and 16 Fr Navarre pigtail catheter (C.R. Bard, Covington, GA).
Outcomes and Definitions
The primary parameter of the study was the incidence of any significant bleeding complication. Significant bleeding complications were defined as a reduction in hemoglobin of >2 g/dL after chest tube insertion, hemothorax, development of a chest wall hematoma or any bleeding requiring blood transfusion, surgery, additional chest tube insertion, or intensive care unit (ICU) admission. Secondary outcomes were the presence of any other local bleeding not meeting the above criteria.
Descriptive statistical analysis was expressed in means, percentages, and frequency.
Baseline demographics and pleural effusions characteristics are shown in Tables 1 and 2, respectively. Forty-three procedures were performed in 30 patients who met inclusion criteria. Patients were predominantly male (70%), with a mean age of 71±10 years. The mean body mass index was 28 (range, 18 to 39). Nine patients were obese with body mass index ≥30. The indications for clopidogrel were coronary stents (50%), acute coronary syndrome (27%), prevention of graft occlusion after coronary artery bypass graft (CABG) (13%), femoral stent or endarterectomy (7%), and carotid endarterectomy (3%). The etiologies of the effusions were post-CABG (48%), heart failure (18.5%), end-stage renal disease (15%), and others (17%). Forty-one procedures (95%) were therapeutic and 2 (5%) were diagnostic. The indications for procedure were respiratory distress (28, 65%), respiratory failure (10, 23%), and pneumothorax (3, 7%). The 2 diagnostic procedures were performed for suspected infection of pleural space.
Twenty-seven procedures were performed with 14 Fr chest tubes, 11 with 8 Fr tubes, and 5 with 16 Fr tubes. The Seldinger technique was used in 29 procedures and modified Seldinger in 14. Fifteen procedures (35%) were performed on 10 patients in the ICU, 6 of them were on positive pressure mechanical ventilation. The amount of fluid drained during first 24 hours was recorded in 33 procedures; the mean volume removed was 1183 mL (range, 500 to 2500 mL).
Most of the patients (91%) were receiving aspirin in addition to clopidogrel. All the patients had a platelet count >50,000/μL and an INR <1.5, with 1 exception where the INR was 1.7. Nine patients had a serum creatinine >2.0 mg/dL but only 1 was >6 mg/dL.
No significant bleeding or any other complications were seen. Preprocedure and postprocedure hemoglobin was recorded in 81% of the cases. No patient had a drop of >1.2 g/dL. In patients who did not have postprocedure hemoglobin, no bleeding events were described in the charts.
The key finding of this study is that when performed by experienced operators, US-guided placement of a small-bore chest tube is safe even in patients on clopidogrel. In the 43 reviewed procedures, there was no occurrence of clinically significant bleeding. This is important because clopidogrel is commonly used to prevent thrombosis in acute coronary syndromes and after coronary stent placement. It is also used to prevent CABG graft closure and for secondary prevention in coronary artery disease, stroke, and peripheral vascular disease. Given the high prevalence of these disorders, it is expected to be a common occurrence for pulmonologists to see patients on this drug who simultaneously need drainage of the pleural space.8
It is important to recognize that the lack of bleeding seen with small-bore chest tube insertion should not be extrapolated to other situations involving invasive procedures. Clopidogrel has been associated with an increased bleeding risk during gastrointestinal procedures (particularly polypectomy),9 and in patients undergoing CABG.10 Furthermore a recent report by Ernst et al11 showed that patients on clopidogrel had an 89% rate of bleeding after a transbronchial lung biopsy compared with a rate of 3.4% in the control group. One study reported that the rate of major gastrointestinal bleeding and bleeding at the site of an arterial puncture in patients on clopidogrel is much higher compared with patients on aspirin alone.12
It is standard practice to discontinue clopidogrel for 5 to 7 days before an invasive procedure.13 This was not possible in our patient group, which was comprised of patients with pleural effusions causing respiratory distress or respiratory failure in whom the procedure could not be delayed or patients with coronary stents where discontinuing therapy would have increased significantly the risk of stent thrombosis.14,15
The risk of chest tube insertion can be diminished by following evidence-based precautions and avoiding situations that involve a known increased risk of complications: they include using US to mark the insertion site and avoiding the procedure in patients on anticoagulation or with bleeding diathesis (PT or PTT greater than twice the midpoint of the normal range, platelet count <25,000 platelets/mm3, or a serum creatinine concentration >6 mg/dL).16,17
Adhering to these measures certainly contributed to the low bleeding complications rate observed in our study but there are 4 additional factors that we believe were relevant to the lack of complications. The first factor is the lateral insertion site at or anterior to the posterior axillary line. This location carries the lowest risk of lacerating the intercostal arteries, the vessels most likely to be the source of excessive bleeding during chest tube insertion. This is directly related to the anatomy of these arteries. In children, the intercostal arteries are usually concealed behind the lower ribs and are not directly accessible to extrathoracic puncture. These arteries tend to sag below the lower rib borders with age which increase their vulnerability; however, this tendency is less prominent with the increasing distance from the spinal column and the arteries are usually protected, even in older individuals, at the point where the ribs angle forward.18,19 The second factor that we believe minimized the risk of complications was the fact that all the procedures were performed under the direct supervision of pulmonologists with extensive experience with pleural procedures. The third factor was the routine use of US guidance to choose the site of insertion. Fourth, was the fact that we avoided the use of large-bore surgical chest tubes and instead exclusively used small-bore tubes that were inserted using Seldinger or modified Seldinger technique.
This study adds to the recent small, but mounting body of literature that supports the safety of performing selected procedures on clopidogrel. Stather et al20 reported no significant bleeding from EBUS-TBNA in a retrospective review of 12 cases. Recent data show that thoracotomy can be performed safely in patients taking clopidogrel.21
Our results are also in agreement with 2 recent publications by Zalt el al22 and Abouzgheib et al23 of small series of patients on clopidogrel who underwent US-guided thoracentesis and small-bore chest tube placement, respectively, without bleeding complications. Our study also highlights that even in patients in the ICU and obese patients, in whom positioning for the procedure can be challenging, no complications occurred.
Our study has limitations: first, it was retrospective and involved a single center; second, the study size was not large enough to detect the bleeding rate of 1% that has been reported in patients not taking clopidogrel; finally, as all the procedures were performed or supervised by highly experienced operators, the results cannot be extrapolated to less experienced operators.
Nevertheless, our findings strongly indicate that US-guided small-bore chest tube insertion in patients on clopidogrel can be safely performed by experienced operators using the lateral insertion site.
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Keywords:© 2013 Lippincott Williams & Wilkins, Inc.
ultrasound; chest tube; bleeding; antiplatelet; clopidogrel; pleural effusion; pneumothorax