Emergency Interventions

Ultrasonography has assumed an increasingly important role in emergency and critical care medicine in recent years. After the history and physical examination, ultrasound is the method of choice for the investigation of a medical acute abdomen.¹ In surgical emergencies it is used in the FAST protocol (focused assessment with sonography for trauma) within the framework of ATLS (advanced trauma life support) and is practiced under a number of other acronyms (FASTER, p-FAST, EFAST, etc.). Ultrasound is used in emergency settings for the rapid detection of free fluid in the abdomen, pleural space, or pericardium. Abdominal ultrasound provides a specificity >90% with a variable sensitivity ranging from 31 to 83%.^2–6 FAST has not yet demonstrated a survival benefit in trauma patients,⁷ although its primary use in an algorithm with secondary CT is advocated in equivocal cases.⁸

Ultrasound provides a technology that “comes to the patient” in critical care situations. Diagnostic uses are paramount, with one study finding that ultrasound-guided interventions accounted for just 0.25% of all indications.⁹ Ultrasound had immediate diagnostic or therapeutic implications in 5.5% of cases and short-term implications in another 20%.

Ultrasound is fast, mobile, economical, and highly sensitive for the detection of free fluids. Consequently, percutaneous interventions should be integrated into the examination:

• 
  

  Diagnostic interventions, followed if necessary by immediate therapeutic interventions, in patients with suspected hemorrhage (hemothorax, hemoperitoneum), empyemas, or abscesses

  
  
• 
  

  Drainage procedures in life-threatening situations (pericardial tamponade, tension pneumothorax)

  
  
• 
  

  Establishing access to central and peripheral veins and arteries

Several international ultrasound societies have proposed or instituted multilevel training programs for emergency sonography. All of these programs include ultrasound-guided interventions in the initial training phase.^10–13

30.1.1 Indications

A number of urgent indications for interventional procedures are recognized in emergency and critical care medicine. They are summarized in ▶ Table 30.1.

Almost all ultrasound-guided interventions in emergency medicine are also practiced in “routine” situations. In this chapter, accordingly, we shall focus our attention on specific issues relating to emergency settings and will otherwise refer the reader to chapters dealing with specific body regions.

Ultrasound can also be used for control purposes before or after critical care interventions: Studies indicate that imaging the neck before a percutaneous dilatational tracheostomy warrants a change of puncture site in 24 to 36% of cases. The rate of major complications can be reduced from 4% to 0%, while the rate of minor complications remains approximately the same (0.7% versus 1%) and the rate of cuff perforations falls from 10% to 0.9%. Ultrasound guidance can also prevent placing the tracheostomy tube too high.^14–16

The correct placement of a conventionally placed endotracheal tube can be reliably confirmed by the “sliding lung sign,” or relative sliding of the visceral and parietal pleura seen at ultrasound. This sign is absent over a nonventilated lung.^17,​18

Ultrasound can reliably detect the presence of a feeding tube for enteral nutrition in the small intestine. This method appears to be particularly useful in children as a means of avoiding radiation exposure.^19,​20

30.1.2 Contraindications

Possible alternatives (CT-guided intervention, surgical intervention) should also be considered in emergencies. No comparative studies have yet been done on the different options that are available in emergency settings. Fewer contraindications exist in emergencies, and it is important to make an individual risk assessment in a patient with impaired coagulation, for example. Physicians still have the obligation to disclose necessary information, except in the case of an acutely life-threatening, unstable situation or an unconscious patient. The timing and scope of the disclosure depend on the severity and urgency of the intervention.

Two basic contraindications remain:

• 
  

  Refusal of informed consent

  
  
• 
  

  Lack of practical implications

30.1.3 Materials and Equipment

Ultrasound Technology

“Bedside ultrasound” and “point-of-care ultrasound” are terms that describe the capability to examine patients almost anywhere using portable devices. The advantage of portable scanners is that they can be delivered quickly to the patient and can even be taken to accident sites by rescue personnel.²¹ Many authors stress the time gained by use of mobile devices in the hospital—which usually means that ultrasound machines are absent at strategically important sites like the emergency room and intensive care unit.

In principle, ultrasound equipment should be available that can image and document relevant structures with optimum quality in every situation. Portable machines are inferior to high-end systems in terms of image quality.^22,​23

No comparative prospective studies have yet been done on interventions with portable ultrasound scanners. One small series (n = 12) reported good results with hand-carried ultrasound-guided pericardiocentesis and thoracentesis.²⁴ In our experience, the success of an ultrasound-guided intervention depends to a substantial degree on the familiarity of the operator with the machine, regardless of its portability.

Superficial interventions in arteries and veins are guided with a 7.5- to 10-MHz linear transducer, while a standard curved-array “abdominal” transducer is used for paracentesis. We also use a high-frequency linear transducer for the aspiration of small pleural effusions.

Interventional Materials

A limited array of interventional materials and supplies are used in emergency settings (▶ Table 30.2). Procedures are simplified by using as few different materials as possible to solve a maximum number of problems.

30.1.4 Antisepsis

The principles of antisepsis are reviewed in Chapter ▶ 8.

The patient’s skin is shaved if necessary and prepared with an alcohol solution. The transducer must be thoroughly cleaned and disinfected before use (e.g., with alcohol- and aldehyde-free wipes). Since the operator will not touch the needle or the patient’s skin in a diagnostic intervention, it is unnecessary to wear sterile gloves. Disposable gloves are worn, however, to prevent contamination with the patient’s blood.²⁵

Following use, the transducer is cleaned with a (nonsterile) towel and again disinfected with antiseptic wipes.

Vascular interventions and the drainage of abscesses and effusions must be performed under sterile conditions. Sterile drapes, gloves, gown, mask, cap, and sterile device covers (for transducer and keyboard) are essential, just as in an operating room.

30.1.5 Problems and Complications

Emergency ultrasonography takes several minutes of calm, steady concentration and should always employ sterile technique. Problems arise when the operator is unfamiliar with the ultrasound machine, space is confined, vision is poor, or multiple concurrent actions are being carried out on the patient (see ▶ Table 30.3).

The complications that may arise in emergency interventions are of the same nature as those in elective settings. To date there have been no systematic studies comparing the complication rates of interventions in emergency settings versus normal conditions. Time pressure, unstable patients, a hectic environment, confined space, and hygienic issues suggest that complication rates are likely to be higher. The complication rates of thoracentesis in ICU patients range from 1.3% to 18% and are comparable to the rates reported in routine settings.^26,​27

30.1.6 Intra-abdominal Free Fluid

A differential diagnosis must be made quickly, and its scope depends on the patient’s history. If the pattern of injury is unclear in a patient with blunt abdominal trauma, or if no organic injuries can be found but emergency ultrasound detects the presence of free fluid, a diagnosis of hemoperitoneum should be confirmed. The sensitivity of ultrasound for detecting intra-abdominal free fluid in the FAST evaluation of trauma patients varies greatly in published studies—as does the proficiency of the examiners. If fluid can be detected, an immediate ultrasound-guided fine needle aspiration should be performed to investigate the cause (hemoperitoneum, ascites, urine). This intervention takes only a few minutes and may be crucial in directing further actions.

In patients with an acute abdomen and/or sepsis and intra-abdominal free fluid, the diagnostic aspiration of ascites can provide a rapid diagnosis and may facilitate the decision for emergency laparotomy by detecting bowel contents, pancreatogenic ascites, purulent fluid, or blood.

Bacterial peritonitis (spontaneous or secondary) should be urgently excluded in patients with hepatic cirrhosis, ascites, and sudden clinical deterioration. Again, immediate needle aspiration may be rewarding as a granulocyte count >240/μL establishes a diagnosis of spontaneous bacterial peritonitis.²⁸

There is no emergency indication for the immediate catheter drainage of intra-abdominal free fluid. Even for spontaneous bacterial peritonitis, there have been no studies comparing patients treated by catheter drainage versus antibiotics only.

Procedure

The steps in the procedure are as follows:

1. 
   

   Locate the ideal puncture site (easily accessible, no interposed vessels, significant fluid volume).

   
   
2. 
   

   Introduce the 20-gauge needle under long- or short-axis ultrasound guidance without prior local anesthesia.

   
   
3. 
   

   The detection of blood or bloody ascites may warrant (exploratory) laparotomy.

   
   
4. 
   

   Ascites should be investigated by chemical and microbiological analysis.

   
   
   
   

   
   

   Caution

   
   

   
   

   Free fluid in the abdomen of emergency room patients requires immediate diagnostic aspiration.

Abscess, Empyema

Abscesses and empyemas (e.g., acute cholecystitis, infected pancreatic pseudocyst) are an urgent but rarely emergent indication for percutaneous drainage. They should always be treated on the same day. This allows enough time to perform these procedures “semielectively” in a calm atmosphere. The puncture and drainage techniques are described in Chapter ▶ 15.

30.1.7 Intrathoracic Free Fluid

A hemothorax may require immediate surgical intervention (e.g., for an aortic dissection), depending on the pattern of injury. Primary chest tube placement is a reasonable option in cases where acute bleeding may have stopped but the patient still has significant respiratory compromise. With a long-standing hemothorax, significant adhesions may develop between the pleural layers.

Large (more than 1/2 hemithorax), loculated effusions and empyemas with a pH <7.2 or positive microbial stain or culture also require immediate chest tube drainage (▶ Fig. 30.1).^29,​30

Traditionally, hemothorax and empyema are treated with a large-bore thoracostomy tube that requires prior blunt surgical dissection of the drainage tract. Pigtail catheters (8–14F) can be placed faster and more easily. They have success rates of 42 to 80% for the drainage of empyema and up to 100% for traumatic hemothorax.^26,​31 We therefore primarily use 10F to 12F drains. An early diagnosis and early initiation of treatment are important because the later formation of septa and adhesions will prevent percutaneous therapy.

If treatment is unsuccessful (no significant improvement in 3 days, clogged drain, poor output), the tube should be promptly exchanged for a large-bore catheter or replaced by thoracoscopic therapy.³⁰

Empyemas can also be treated by instilling fibrinolytic agents (streptokinase, urokinase) into the pleural cavity. This treatment achieves higher cure rates than saline irrigation. The role of drainage compared with primary thoracoscopic therapy cannot be definitively assessed at present.^29,​32

Procedure

The steps in the procedure are as follows:

1. 
   

   Place the patient in a sitting position if possible.

   
   
2. 
   

   Locate the ideal puncture site (easily accessible, superior rib border, significant fluid volume).

   
   
3. 
   

   Introduce the 20-gauge needle (diagnostic) under long- or short-axis ultrasound guidance without prior local anesthesia.

   
   
4. 
   

   Then administer local anesthesia if required.

   
   
5. 
   

   Make a stab incision.

   
   
6. 
   

   Introduce a pigtail catheter along the superior rib border using trocar technique. With large effusions, the skin site can be marked under sonographic guidance and the needle inserted without continuous imaging (▶ Fig. 30.1, ▶ Fig. 30.2).

   
   
7. 
   

   Connect a three-way stopcock and reservoir with water seal; suction may be applied if needed (15 cm H₂O).

   
   
8. 
   

   Analyze the aspirate according to etiology: infectious → microbiology, Ziehl-Neelsen stain, pH, WBC, clinical chemistry; traumatic → Hb; malignant: → cytology.

   
   
   
   

   

   
   

   Fig. 30.2 Drainage of an empyema in a severely dyspneic patient under sonographic guidance using the trocar technique.

   
   

   a Transducer placement and drain insertion using sterile technique.

   
   

   b Corresponding ultrasound image. The drain appears as a linear echo entering the image from the right side. Multiple septa have already formed within the empyema, appearing as echogenic lines.

30.1.8 Pneumothorax

Ultrasound is more sensitive than standard chest radiographs in the diagnosis of pneumothorax^33,​34 and therefore is an effective guidance modality for treatment. While ultrasound cannot display the position of the drain in the pneumothorax, it can determine whether pneumothorax is actually present at the proposed puncture site.

Adequate drainage can usually be obtained with 7F to 9F pigtail catheters, which have an 84 to 97% success rate for drainage periods of 2 to 4 days. Single or repeated needle aspiration is an alternative for idiopathic pneumothorax.^35,​36 If a drainage tube is placed, an oblique intra- and subcutaneous tunnel should be developed to prevent recurrence after drain removal (see also Chapter ▶ 24).

Procedure

1. 
   

   Elevate the upper body 30 to 45°.

   
   
2. 
   

   Localize free air by ultrasound and administer local anesthesia at the typical Monaldi site (second or third intercostal space in the midclavicular line) or at an atypical site if the pneumothorax is incomplete or accompanied by adhesions.

   
   
3. 
   

   Make a stab incision.

   
   
4. 
   

   Introduce an 8F to10F pigtail catheter along the superior rib border using trocar technique.

   
   
5. 
   

   Connect a three-way stopcock and water-seal suction at 15 cm H₂O.

30.1.9 Pericardial Fluid

Pericardial tamponade is a life-threatening condition that may have a malignant, infectious, postoperative, or occasionally a traumatic etiology. Echocardiography typically shows “swinging heart” motion within the pericardium (▶ Fig. 30.3). The right atrium and possibly the left atrium show diastolic collapse, and the right ventricle may collapse at end diastole. Even small effusions may be life threatening: the clinical parameters of hypotension, tachycardia with a paradoxical pulse (i.e., pulse diminished on inspiration), and distended neck veins are considered indications for pericardiocentesis. An aortic dissection should first be excluded as the cause, as it would necessitate primary surgical treatment.³⁷ Ultrasound has a sensitivity of 100% and specificity of 96.9% in the detection of traumatic pericardial effusion.³⁸

Ultrasound-guided drainage has been described as safe and effective in several clinical series, with success rates of 97 to 99.1%. Major complications (1.3%) are ventricular injury, hemopneumothorax, and sustained ventricular tachycardia (3%) while minor complications have a reported incidence of 3.5% in the largest published series.^39,​40

The ideal puncture site is not necessarily subxiphoid, which was once considered standard. With ultrasound guidance, the needle can be introduced at the site where the effusion volume is greatest and the distance from the skin surface is short with no critical intervening structures. The injection of NaCl or HES (hydroxyethyl starch), for example, will produce a “white cloud” that accurately marks the position of the puncture needle and drain (▶ Fig. 30.4, ▶ Fig. 30.5).⁴¹

We use a single-lumen 14-gauge central venous catheter for pericardial drainage, since all physicians are familiar with its use. Pericardiocentesis sets usually include approximately 8F drains and dilators (e.g., from Cook Medical). It is not necessary to have an ECG lead attached to the needle hub when ultrasound guidance and skin surface leads are used.

Procedure

1. 
   

   Elevate the upper body 30 to 45°.

   
   
2. 
   

   Start ECG monitoring.

   
   
3. 
   

   Administer local anesthesia under sonographic guidance.

   
   
4. 
   

   Make a stab incision.

   
   
5. 
   

   The needle is usually introduced under sonographic guidance. On entering the pericardial sac, inject agitated NaCl or HES to check the needle position.

   
   
6. 
   

   Change to Seldinger wire and insert a drain primarily or after dilating the tract.

   
   
7. 
   

   Recheck placement by injecting NaCl or HES.

   
   
8. 
   

   The aspiration of bright red blood may indicate puncture of a coronary artery, the right ventricle, or the left ventricle if an apical approach was used.

   
   
9. 
   

   Analyze the aspirate according to etiology: infectious → microbiology, Ziehl-Neelsen stain; traumatic (or bloody aspirate) → Hb; malignant → cytology.

30.2 Percutaneous Vascular Interventions

30.2.1 Vascular Access

Central venous catheterization was traditionally done “blindly” on the basis of designated anatomical landmarks. Ultrasound improved this technique by allowing the operator to image the target vessel in two planes and then mark its course on the skin, followed again by a “blind” needle insertion (▶ Fig. 30.6a, b). In any case, the target vessel must be imaged sonographically before the intervention in order to detect any positional anomalies and avoid puncturing a thrombosed vein (▶ Fig. 30.7).

On the basis of the results of two meta-analyses, central venous catheter placement under continuous ultrasound guidance results in fewer placement attempts and fewer malplacements in the internal jugular vein, subclavian vein, and femoral vein of adults and the internal jugular vein of children, reducing overall complication rates from 10.2% to 4.6%. The differences in time to catheter placement and costs (including device acquisition) were not clinically relevant compared with the landmark technique.^42–44

Another study showed that real-time ultrasound guidance also reduced complications relative to the landmark technique under emergency conditions using a portable scanner.⁴⁵ Central venous catheterization under ultrasound guidance has been incorporated into the British guidelines of the National Institute for Health and Care Excellence.⁴⁶

The needle can be visualized in a long-axis view with the vessel imaged in longitudinal section, or a short-axis orientation can be used. In the short-axis view the needle cross-section appears as a punctate echo. The needle tip can be identified only by gently oscillating the transducer. The long-axis view displays the full length of the needle, making it easier to avoid penetration of the posterior vessel wall (▶ Fig. 30.8, ▶ Fig. 30.9).

The internal jugular vein is the vessel most often catheterized and is excellent for learning the ultrasound guidance technique. Even physicians unfamiliar with general diagnostic ultrasound can quickly master the long-axis imaging technique with a little practice. It takes some practice to work synchronously with both hands, i.e., holding the transducer in one hand while inserting the needle with the other.

There are very few occasions where a central venous catheter must be placed within a few minutes without benefit of an ultrasound machine. Given the smaller number of placement attempts and needle redirections, placement of a central venous catheter (CVC) under continuous ultrasound imaging guidance should be standard practice. It can significantly reduce the incidence of complications.

Procedure

1. 
   

   Help from an assistant in sterile attire is ideal.

   
   
2. 
   

   Place the transducer in a sterile probe cover.

   
   
3. 
   

   The operator should wear sterile operating room attire.

   
   
4. 
   

   The patient is positioned supine. A head-down tilt may be added to improve venous filling.

   
   
5. 
   

   For puncture of the internal jugular vein, the operator stands behind the patient’s head with the ultrasound machine next to the patient. For puncture of the subclavian vein, the operator stands on the ipsilateral side next to the patient (▶ Fig. 30.8a).

   
   
6. 
   

   First image the vessel in a long-axis (longitudinal) view and short-axis (cross-sectional) view.

   
   
7. 
   

   Inspect the vessel and its surroundings (atypical location? thrombi? venous valves?).

   
   
8. 
   

   Image the vessel in a long-axis view proximal to the puncture site.

   
   
9. 
   

   Administer local anesthesia under sonographic guidance.

   
   
10. 
    

    Introduce the needle using Seldinger technique in a long-axis view that shows the full needle path. Insertion of the puncture needle and wire is monitored on the screen. After that, any tract dilation and exchange for the CVC can be done with or without real-time ultrasound guidance (▶ Fig. 30.8b–d, ▶ Fig. 30.9).

Even deep or nonpalpable peripheral veins can be reliably catheterized in (obese) adults and children with difficult intravenous access when ultrasound guidance is used.^47,​48 With a tourniquet on the upper arm, the vein is imaged in a long-axis view proximal to the puncture site. The operator holds the transducer in one hand while introducing the needle with the other (▶ Fig. 30.10). Skin antisepsis and transducer disinfection are sufficient for the placement of a simple indwelling venous cannula, taking care not to touch the transducer with the cannula.

Ultrasound can also be used successfully for arterial cannulation (blood gas analysis, invasive blood pressure measurement). For this application we usually introduce the needle in a short-axis view (▶ Fig. 30.11). Before the puncture, the patency of both forearm arteries (radial and ulnar arteries) is assessed by color Doppler ultrasound to avoid inducing critical ischemia in the hand.

Related posts:

Informed Consent Percutaneous Sclerotherapy of Cysts Contraindications, Complications, and Complication Management Fine Needle Aspiration Biopsy and Core Needle Biopsy Indications for Diagnostic Interventions in the Abdomen and Thorax (Liver, Pancreas, Spleen, Kidneys, Lung, Other Sites) Neurologic Interventions, Ultrasound-Guided Regional Anesthesia

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