Ultrasound-guided regional anesthesia in the intensive care unit

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. 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.

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. 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. Moreover, the volume (dose) of LA required to achieve a complete block is decreased under US guidance. ^,

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. ^{, ,}

  • 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. 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. 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.

• 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.

• 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.

• 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. ^,

• 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

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

Regional anesthesia of the upper extremity

Anesthesia of the brachial plexus can be performed in the interscalene groove (interscalene approach), directly above the clavicle (supraclavicular approach), under the clavicle (infraclavicular approach), and in the axilla (axillary approach). The different approaches are not equally suitable for ICU patients. An interscalene brachial plexus block provides good analgesia for the shoulder, arm, and forearm, but the phrenic nerve is usually blocked as well, which results in paralysis of the ipsilateral diaphragm ( Figure 53-1 ) . This effect can aggravate respiratory problems and lead to respiratory failure in compromised, spontaneously breathing patients. Severe complications (i.e., injection of LA into the spinal cord) have been reported after interscalene blocks performed under deep sedation or general anesthesia, and the ASRA guidelines strongly recommend against performing this block under these conditions. Hematoma formation in this area can lead to airway compromise and compression of the neck vessels. Paralysis of the ipsilateral diaphragm is less common with the supraclavicular approach. The supraclavicular approach offers good analgesia to the entire arm, forearm, and hand ( Figure 53-2 ) . US-guided techniques can reduce the risk for pneumothorax by meticulous control of passage of the needle and observation of the anatomic structures: artery, rib, and pleura. However, US-guided techniques cannot entirely prevent the typical complications of these two blocks (i.e., pneumothorax, intraneural injection). With both approaches (interscalene and supraclavicular), the plexus is close to the skin, and dislocation of a regional anesthesia catheter occurs easily with movement. Tunneling of the catheter can reduce this risk.

The infraclavicular approach provides good analgesia to the lower part of the upper arm, elbow forearm, and hand. In this area the brachial plexus is more distant from the skin than with the other approaches (Figure 53-3 A,B). The needle passes in a relatively steep angle under the US probe, which makes visualization of the needle more difficult, but the use of echogenic needles or needle guidance systems is effective in minimizing this challenge. Apart from this technical issue, the infraclavicular approach is excellent for ICU patients because it provides good analgesia and catheter dislocation is less likely than with the aforementioned approaches.

The axillary approach provides the most peripheral access to the brachial plexus, and it results in good analgesia to the elbow, forearm, and hand. With this approach the plexus is located just under the skin, and the surrounding vessels can easily be compressed and thus be subject to accidental vascular puncture. Despite this technical challenge, the axillary approach is an excellent option for ICU patients (Figures 53-3 C,D). Technical details regarding the aforementioned blocks in adult and pediatric patients are presented later.

The brachial plexus innervates the shoulder and the entire arm. It is formed by the anterior rami of nerves exiting the spinal cord (C5-T1 with contributions from the C4 and T2 roots). The usual indications for performing brachial plexus blocks are surgical anesthesia, postoperative analgesia (catheter techniques) and sympathetic blockade for various chronic types of pain, and vascular insufficiency syndromes.