Ultrasound-guided regional anesthesia in the intensive care unit

BETTINA U. SCHMITZ, MARIA MATUSZCZAK, MARCO A. FONDI, SARA GUZMAN-REYES, LUDWIG H. LIN and SAMER NAROUZE

Overview

Peripheral regional anesthesia and neuraxial anesthesia are well established in postoperative pain management following major orthopedic, thoracic, and abdominal procedures. Benefits include pain control superior to that achieved with systemic opioids, improved lung function after thoracic and abdominal procedures, and decreased stress/inflammatory responses.1–6 Ultrasound (US) guidance for regional anesthesia has been used increasingly over the last decade because it allows precise positioning of the catheter and local anesthetic (LA) and thus decreases the amount of LA required to achieve a complete block. In addition, the incidence of vascular puncture is lower with US guidance, thereby increasing the safety of the procedure. Fewer needles passes and replacement of nerve stimulation and subsequent muscle contraction with US visualization minimize procedural pain in patients.

Patients are frequently admitted to the intensive care unit (ICU) with neuraxial or peripheral regional anesthesia catheters placed in the operating room (OR) for postoperative pain management; less commonly, regional anesthesia is initiated in the ICU or implemented on ICU patients in the OR.

In critical care patients, pain can originate from multiple sites, and even though regional anesthesia will not eliminate the need for systemic opioids in most patients, inclusion of regional anesthesia in the pain management regimen can nonetheless result in a significant decrease in overall opioid and sedative requirements. Additionally, these advantages are attractive in the context of the recent paradigm shift toward less sedation in ICU patients.⁷

This chapter outlines the advantages of US-guided regional anesthesia techniques, the benefits of and indications for neuraxial and peripheral regional anesthesia for ICU and non-ICU patients, concerns associated with and contraindications to regional and neuraxial anesthesia, and a brief description of various US-guided regional anesthesia procedures (detailed descriptions of these procedures for adult and pediatric patients are available online).

Advantages of ultrasound guidance for regional anesthesia

Recent data suggest that US guidance improves the success rate and quality of regional anesthesia procedures.8–11 It allows visualization of the neural and surrounding structures in the region of interest (ROI), and real-time US guidance can demonstrate and be used to optimize spread of LA. This is presumably why US-guided nerve block techniques shorten procedure time, hasten onset of the block, and result in fewer needle passes and a decreased incidence of vascular puncture.¹² Moreover, the volume (dose) of LA required to achieve a complete block is decreased under US guidance.¹³^,¹⁴

The decreased incidence of accidental vascular puncture and the lower volumes needed to achieve an effective block can lessen the risk for LA toxicity. Additionally, US-guided regional anesthesia can replace functional (nerve stimulation) localization of the targeted neural structures, which can result in significant discomfort and pain in patients with injuries and fractures.

Conditions in which the ability to visualize target structures with US may be restricted include very deeply located neural structures, such as the lumbar plexus, and the presence of bones partially obscuring the neural structures, such as the epidural space.

Benefits of ultrasound-guided regional anesthesia in patients in the intensive care unit

US-guided regional anesthesia has a number of confirmed and potential benefits in critical care patients:

1. Better pain control. Multiple studies have documented the superior pain control in patients receiving epidural analgesia or paravertebral analgesia after rib fractures, thoracotomy, and major abdominal surgery. Superior pain control is also achieved by the implementation of regional anesthesia in patients undergoing surgery on the extremities.⁴^,⁶^,¹⁵

In the ICU, trauma patients often have multiple injuries. Use of regional anesthesia techniques for all injuries at the same time might be not feasible in most trauma cases. Sequential regional anesthesia, according to the surgical interventions, can reduce baseline and procedural pain and the need for opioids in this population.¹⁶ Bolus injections of LA instead of continuous infusion, as well as a lower concentration and volume of the LA solution, can reduce the overall amount of LA used per day and thereby enable performance of regional anesthesia in more than one location in the same patient.

2. Lower requirement for systemic opioids and sedation. Multiple studies have documented better outcomes and decreased levels of sedation in ICU patients. The American College of Critical Care Medicine addressed these results in practice guidelines published in 2013 in which lighter sedation was recommended for most ICU patients.⁷ However, decreasing the level of sedation in ICU patients without sacrificing good pain control can be challenging. Regional anesthesia provides excellent pain control without affecting the mental status of patients.

3. Improved pulmonary function after thoracic or abdominal surgery and rib fractures. Nishimori et al documented in a Cochrane review that epidural anesthesia improves pulmonary function and reduces the duration of mechanical ventilation in patients undergoing abdominal aortic surgery.¹⁵

4. Possible decrease in the development of chronic pain through better management of acute pain. Chronic pain as a sequela of severe undertreated acute pain is well described. However, data supporting the fact that regional anesthesia for the treatment of acute pain can reduce the incidence or severity of chronic pain are still scant. In a retrospective study, Salengros et al documented a higher incidence of allodynia and chronic pain in patients undergoing thoracotomy with high-dose remifentanil anesthesia than in those with epidural anesthesia and low-dose remifentanil.17–19

5. Sympathicolysis. Sympathicolysis is a well-described effect of regional anesthesia that can be beneficial for patients with impaired perfusion of the extremities because of vascular disease or trauma.¹⁹

6. Possible impact on recurrence of cancer. Surgical stress and opioids are known to suppress the immune system. Some retrospective studies have shown a lower recurrence rate of cancer in patients treated with regional anesthesia and propofol infusion than in those undergoing anesthesia with opioids and inhalational anesthetics. However, other studies could not confirm these statements, and prospective studies are in progress. Whether better postoperative pain control with regional anesthesia and less use of opioids postoperatively have an influence on tumor recurrence is not certain.²⁰^,²¹

7. Impact of regional anesthesia on mortality and duration of hospital stay. Currently, the overall evidence showing improved mortality and reduced duration of hospital stay after regional or neuraxial anesthesia is insufficient (Box 53-1).

BOX 53-1

BENEFITS OF REGIONAL ANESTHESIA

Proven benefits

Better pain control than with systemic opioids for extremity surgery, thoracic and abdominal surgery, and rib fractures

Decreased requirements for postoperative systemic opioids

Improved pulmonary function after thoracic surgery, abdominal surgery, and rib fractures

Decreased stress response (thoracic epidural)

Sympathicolysis

Possible benefits

Decreased requirement for opioids and sedatives in patients in the intensive care unit

Decreased severity and incidence of chronic pain syndromes

Decreased metastasis and recurrence rate in cancer patients

Concerns and problems related to neuraxial and peripheral regional anesthesia in patients in the intensive care unit

Patient-related concerns and problems

1. Coagulopathy and systemic infection. Coagulopathy and systemic and local infection are contraindications to regional anesthesia; moreover, these conditions are prevalent in ICU patients. The American Society of Regional Anesthesia (ASRA) guidelines regarding patients receiving antithrombotic or thrombolytic therapy should be followed. When regional anesthesia procedures are performed in patients with borderline coagulation status, more peripheral approaches (axillary, femoral, fascia iliaca compartment, and popliteal sciatic) should be considered. However, finding a window of appropriate coagulation to safely remove indwelling catheters can be challenging.²²

2. Regional anesthesia under deep sedation or anesthesia. Decreasing sedation to facilitate communication with patients during regional anesthesia procedures is not always possible. Deep sedation or anesthesia abolishes the ability of the patient to report symptoms pertinent to LA toxicity or nerve damage. Accordingly, the ASRA recommendations (2008) do not support the routine performance of neuraxial or interscalene blocks in anesthetized or heavily sedated patients. However, the group acknowledged that the risk-benefit ratio can be favorable for regional anesthesia under the aforementioned conditions in selected cases. Neuraxial and peripheral regional anesthesia in pediatric patients under heavy sedation or anesthesia is considered more applicable, mainly because of the inability of pediatric patients to communicate symptoms of toxicity or nerve injury and the potential harm associated with patient movement.

Systemic LA toxicity and nerve damage have been reported even after US-guided peripheral nerve blocks. Meticulous needle control, observation of LA spread, verification of the position of the tip of the catheter with hydrodissection, avoidance of intraneural injection or catheter placement, use of a test dose, and slow injection of LA in small increments can reduce risk for the aforementioned complications.²³

3. Risk for compartment syndrome. Compartment syndrome is a complication of extremity trauma. Regional anesthesia itself does not increase the risk for compartment syndrome, but it could mask the associated pain and delay detection. Thus, the lowest effective concentration of LA solution should be infused. Whether this consideration is relevant for an intubated and sedated ICU patient can be questioned. However, because compartment syndrome is a limb-threatening complication, regional anesthesia in patients with high-risk injuries such as tibial and distal radial fractures should be discussed with the orthopedic surgeon, and measurement of compartment pressure should be considered.²⁴^,²⁵

4. Positioning. Positioning of traumatized patients for regional anesthesia can be challenging.

Organization-related concerns and problems

1. Training. ICU personnel caring for patients with neuraxial or peripheral regional anesthesia catheters in place need to be adequately educated regarding regional anesthesia and its benefits, possible adverse effects, and complications.

2. Implementation of care protocols. Detailed protocols for the care and follow-up of patients who receive neuraxial or peripheral regional anesthesia should be implemented.

3. Color marking of different access lines. Adding another line to the already numerous lines inserted and attached to patients in the ICU increases the risk for misidentification of neuraxial/regional infusion and intravenous infusion lines. Judicious color marking of the different lines and their connections can reduce this risk.

4. Infection. The risk for infection with an indwelling catheter is higher in ICU patients. The insertion site of the neuraxial or regional anesthesia catheter should be inspected at least once daily for signs of infection and the findings documented.

5. Catheter dislocation. Accidental dislocation or removal of neuraxial or regional anesthesia catheters during mobilization and transportation is a potential problem. The integrity of all indwelling catheters should be checked routinely after mobilization and transport of patients.

6. The future of LA catheters. Extended-release LA formulations might decrease the need for insertion of catheters for continuous LA infusion in the near future.

Table 53-1 lists common indications for neuraxial and peripheral regional anesthesia, whereas Box 53-2 outlines barriers and contraindications to US-guided regional anesthesia in critical care patients.

BOX 53-2

BARRIERS AND CONTRAINDICATIONS TO ULTRASOUND-GUIDED REGIONAL ANESTHESIA IN THE INTENSIVE CARE UNIT

Patient related

Infection (local or systemic)

Coagulopathy

Antithrombotic, fibrinolytic therapy

Sedation status

Multiple injuries

Positioning problems for a regional anesthesia procedure

Lack of knowledge/inexperience regarding side effects and complications of regional anesthesia

Lack of protocols for patients with regional anesthesia

TABLE 53-1

Indications for Neuraxial and Peripheral Regional Anesthesia in ICU and non-ICU patients

Indication	Non-ICU patient	ICU Patient
Upper extremity analgesia	Joint replacements (shoulder, elbow, hand) Fractures Tendon and muscle repair Vascular surgery Arteriovenous grafts Reimplantation of the finger, hand, and arm	Joint replacements (shoulder, elbow, hand) Fractures Tendon and muscle repair Vascular surgery Arteriovenous grafts Reimplantation of the finger, hand, and arm
Upper extremity sympathicolysis	Ischemia Reimplantation Vascular surgery	Ischemia Reimplantation Vascular surgery
Lower extremity analgesia	Joint replacements (hip, knee, ankle) Fractures Tendon and muscle repair Vascular surgery	Joint replacements (hip, knee, ankle) Fractures Tendon and muscle repair Vascular surgery
Lower extremity sympathicolysis	Ischemia Vascular surgery	Ischemia Vascular surgery
Trunk	Thoracotomy/thoracoscopy Rib fractures Abdominal wall incision	Thoracotomy/thoracoscopy Rib fractures Abdominal wall incision
Neuro-axial	Rib fractures Thoracic surgery Abdominal surgery	Rib fractures Thoracic surgery Abdominal surgery Ileus Pancreatitis

ICU, Intensive care unit.

Timing of regional anesthesia

Regional anesthesia procedures are most commonly performed perioperatively in the OR suite, and patients are subsequently admitted or readmitted to the ICU for further management. However, such procedures can just as well be performed in the ICU, depending on the individual circumstances and condition of patients.

In either location, equipment for airway management and resuscitation and for intralipid infusion, as well as a local anesthesia toxicity checklist, should be available at the bedside of patients. All blocks should be performed with standard American Society of Anesthesiology monitoring in place and patients supervised by trained personnel after injection of the LA.

Ultrasound technique for regional anesthesia

Ultrasound scan

According to the HOLA concept of US scanning, a preprocedural scan facilitates the visualization of anatomic structures in an ROI, such as nerves, vessels, bones, muscles, and fascia layers (see Chapters 1 and 51). Nerves have a fascicular hyperechoic appearance and are obviously the primary targets during guided nerve blocks. Transverse and longitudinal US views can identify the nerve and confirm spread of the LA along single nerves. Transverse views are less technically complex and used mainly during real-time LA injection. Two-dimensional scanning can be extended (proximally and distally) to identify the location and track the course of neural structures. Such tracking may optimize identification of the target nerve by visualization of adjacent anatomic structures or landmarks (e.g., musculoskeletal, vascular) and their two-dimensional alignment in relation to the former in an ROI.¹²