Ultrasound-Guided Percutaneous Drainage

Kazuhide Matsushima, MD*
Division of Trauma
Acute Care and Critical Care Surgery
Penn State Milton S. Hershey Medical Center
Hershey, Pennsylvania, USA

Heidi L. Frankel, MD, FCCM**
Division of Trauma
Acute Care and Critical Care Surgery
Penn State Milton S. Hershey Medical Center
Hershey, Pennsylvania, USA

At four a.m., you are called to evaluate a patient who underwent emergency surgery for perforated sigmoid diverticulitis one week earlier. The patient is febrile (39.5Cº), and his blood pressure has dropped to 78/44 mm Hg. After resuscitation, you obtain a computed tomographic (CT) scan that shows an intraabdominal abscess in the left lower quadrant. The interventional radiologist is otherwise occupied and unavailable to drain the collection promptly. The patient is now profoundly confused. What is your next step?

Background
Bedside ultrasound performed by intensivists has been gaining popularity in the intensive care unit (ICU) setting.(1) In addition to its portability and efficiency, the accuracy and efficacy of intensivist- performed ultrasound has been demonstrated for a broad spectrum of indications.(2-4) Since the 1990s, the success rate for central venous catheter cannulation has improved significantly with the introduction of real-time ultrasound guidance.(5) This technique is now recommended in several procedures, especially internal jugular vein cannulation.(6) With the recognition of Focused Assessment with Sonography for Trauma (FAST) as an important modality in the trauma and critical setting,(7) ultrasound now is a diagnostic and therapeutic tool that is not limited to use by the radiologist or cardiologist. For example, echocardiography by intensivists can predict the hemodynamic status of critically ill patients accurately.(2) Pneumothoraces occurring in the patient requiring mechanical ventilation can be identified using bedside ultrasound without any exposure to ionizing radiation or transport to the CT suite.(8)

In addition to diagnositic and monitoring purposes, ultrasound can be used to guide interventional bedside procedures efficiently and safely. We describe several examples of such use.

Thoracentesis and Thoracic Drainage
Pleural effusions are common complications in the ICU setting. Moderate to large fluid collections may compromise the patient’s respiratory status. Ultrasound detection of pleural effusions is performed by placing the lowfrequency transducer probe on the lateral chest wall (Figure 1). In general, if a fluid collection larger than 2 cm is identified, real-time ultrasound-guided thoracentesis or drainage can be performed safely. Several reports have demonstrated the efficacy of this technique, even for patients requiring positive pressure ventilation.(9,10)

With the patient in the supine position or the head of bed elevated to 30 degrees, a low-frequency (3.5 to 5 MHz) ultrasound transducer will depict a fluid collection in the chest cavity as a low echogenic area (black). The fifth to seventh intercostal space at the midaxillary line is generally targeted; however, an elevated diaphragm due to supine positioning or body habitus (obese, edematous) may be encountered. The anatomical relationship between the diaphragm (liver), lung parenchyma and fluid collection must be clarified to select the appropriate level for tube insertion. Although a pre procedural skin marking technique can be performed, we prefer to use real-time ultrasound guidance in ICU patients.|

In addition to the usual standard sterile skin preparation and draping, the ultrasound transducer probe is covered by a sterile plastic sleeve. Sterile ultrasound gel is placed on the patient, but must also be placed on the transducer inside of the sleeve (Figure 2). There are several manufacturers of such devices.(11) After anesthetizing the skin with lidocaine, the introducer needle is advanced above the rib with ultrasound guidance through the parietal pleura. An experienced provider may hold the transducer with one hand and the needle in the other hand. Trainees or novices may considered a two-person approach with one person holding the transducer and the other advancing the needle (Figure 3). Ultrasound guidance also is helpful when draining smaller volume collections. The tip of needle will be visualized as a highly echogenic linear structure in the ultrasound image (white) and fluid can be withdrawn though the syringe. Using the Seldinger technique, a pigtail drainage tube is placed and connected to a regular chest tube drainage device. A chest radiogram should be ordered for confirmation (Figure 4, 5).

In their retrospective review, Gammie and colleagues(12) reported that pigtail catheter drainage was clinically successful in 86% of pleural effusion cases without radiological guidance, but four cases of failure were associated with a loculated fluid collection that could be indentified with ultrasound. Recently, the outcome of intensivistperformed ultrasound guidance for pigtail catheter drainage was demonstrated by Liang and colleagues.(13) Although most postoperative effusions and traumatic hemothoraces were treated successfully, only 42% of parapneumonic effusions/empyemas improved with pigtail catheter drainage. In 133 cases, no pneumothoraces and one hemothorax resulted from catheter placement.

Intraperitoneal and Retroperitoneal Drainage
Image-guided percutaenous drainage is considered the standard treatment for intraperitoneal/retroperitoneal abscesses or fluid collections. CT guidance, a common imaging modality for percutaneous drainage,(14) can be performed at the bedside safely when transport of the intensive care patient to the radiology suite is not possible or safe. On the other hand, ultrasound-guided percutaneous drainage can be performed at the bedside safely.

Two factors must be considered before conducting an image-guided intraperitoneal/retroperitoneal drainage procedure in the ICU:

• The cavity or fluid collection must be well visualized with ultrasound
• There can be no vascular structure or hollow viscus (small bowel, colon) between the body wall and targeted area

Except for large volumes of free fluid (e.g., ascites), real-time ultrasound guidance is mandatory. Most of the procedure is identical to that of thoracic drain placement, except the type of drainage catheter is adjusted based on the characteristic of the fluid and location of the collection.

Percutaneous Cholecystostomy
Acute cholecystitis, including acalculous cholecystitis can be a source of severe sepsis/septic shock in critically ill patients. Bedside ultrasound has been shown to be useful and accurate in the establishment of these diagnoses.(15) Although laparoscopic cholecystectomy is the first choice of treatment for acute cholecystitis, unstable septic patients may not be amenable to operative intervention. Alternatively, image-guided percutaneous gallbladder aspiration or drainage tube placement (cholecystostomy) can be performed at bedside safely with favorable outcome.(16)

We prefer the percutaneous transhepatic approach to percutaneous direct, as the former presents a lower risk of bile leakage and incidental tube dislodgement. On the other hand, one must be careful when using the percutaneous transhepatic approach to avoid a diaphragm puncture, which can result in pneumo- or hemothorax or empyema. Even if the gallbladder is distended by acute inflammation, real-time ultrasound guidance is required to target the localized area. Aspirating bile is usually a promising sign that the tube or needle is inside the gallbladder. We routinely repeat the ultrasound study to ensure the tip of tube is in the correct location (i.e., the gallbladder).

Conclusion
The ease and utility of bedside ultrasound is expanding in the ICU setting. The role of intensivist-performed interventional procedures has great potential to improve patient care through gains in efficiency and safety.

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