**4. Pain management for the thoracic surgical patient**

#### **4.1. Post-thoracotomy pain syndrome**

**ii.** Pneumothorax

26 Principles and Practice of Cardiothoracic Surgery

avoid formation of a pneumothorax.

**iii.** Cardiac herniation

Pneumothorax is a potentially grave immediate postoperative complication that may neces‐ sitate prompt intervention. The creation of a pneumothorax is inherent in any procedure involving the breach of the thoracic cavity. The severity of pneumothorax is determined by its magnitude and whether it is in communication externally with atmospheric pressure. A pneumothorax of small volume is usually well tolerated; however, with increased magnitude, it exerts considerable effects to the heart and vasculature in the confined space of the thoracic cavity. These may lead to hemodynamic collapse and respiratory compromise – a tension pneumothorax. Chest drainage tubes are used to decrease the magnitude of a pneumothorax by providing an avenue of escape for trapped air (and/or blood, secretions, etc.) from the thoracic cavity. Specialized "balanced" drainage systems have been developed for certain operations, such as pneumonectomy. Balanced systems provide a buffer to prevent excessive negative or positive intrathoracic pressures from developing, lowering the chance for both tension pneumothorax and cardiac herniation (see below) [105]. In circumstances where chest tubes are not placed or where the drainage system malfunctions, tension pneumothorax may develop. In this scenario, intrathoracic pressures must be relieved immediately via needle decompression and/or emergent chest tube insertion. One must recognize that contralateral pneumothorax is also a possibility from anesthetic (contralateral central venous catheters, epidural (paramedian) placement, barotrauma) as well as surgical (breach of the contralateral pleura) insult [106]. Care must be taken to avoid clamping chest tubes after thoracotomy to

Cardiac herniation, although rare, is a potentially fatal postoperative complication most commonly associated with disruption of the pericardium – most commonly during the course of or after a pneumonectomy. The usual presenting symptoms are generalized hypotension and tachycardia; however, right versus left sided cardiac herniation may present with additional distinct signs and symptoms inherent to the physiologic disruption unique to the direction of herniation [107, 108]. Leftward herniation places the heart at risk for myocardial ischemia and arrhythmias, because of the potential constriction of the ventricles by pericardial tissue during the course of the herniation [107, 108]. Rightward herniation predisposes the patient to superior vena cava (SVC) syndrome – head, neck and upper-extremity cyanosis, edema, etc. - secondary to torsion and obstruction of the SVC and inadequate cardiac preload because of impaired venous drainage [107, 108]. After assessing signs and symptoms, cardiac herniation may be confirmed via imaging - chest x-ray and/or echocardiography. Immediate surgical intervention to reduce the herniation and correct the pericardial defect is paramount to prevent further hemodynamic collapse [107, 108]. The gravity of cardiac herniation warrants recovery measures to help minimize its occurrence. Avoid patient positioning with the operative side dependent, to reduce gravitational effects favoring herniation. As discussed above, early extubation is favored to alleviate the effects of positive pressure ventilation and its tendency to instigate and worsen herniation. Lastly, avoid negative pressure via chest drainage tubes (preferably using balanced chest drainage systems in pneumonectomies) to

minimize a vacuum effect that may predispose to herniation [107, 108].

Thoracotomies continue to cause substantial pain because of the degree of surgical injury. Insult to the intercostal nerves, soft tissue damage and inflammation, bone and joint disturb‐ ance, and visceral manipulation all contribute to the severity of pain[88]. The estimated incidence of chronic pain following thoracotomy is between 30-40%, with approximately 10% with severe disabling pain [109, 110]. Pain control is crucial after thoracic surgery not only for immediate pain relief, but also to prevent pulmonary complications.

"Pain that recurs or persists along a thoracotomy scar at least two months following the surgical procedure" [111] is the definition of post-thoracotomy pain syndrome (PTPS). Poor pain management after thoracotomy may contribute to PTPS [112]. The pain is largely described as aching, with tenderness and numbness at or around the surgical incision/scar [113]. In contrast to acute pain, which mostly affects respiratory function, PTPS may be responsible for inability to perform daily activities. Although PTPS likely plays a negative role in daily life, its impact is unclear because these subjective phenomena have not been reliably assessed [113, 114].

Although video assisted thoracic surgery (VATS) was anticipated to reduce pain when compared to traditional posterolateral thoracotomy, its smaller port sites do not necessarily avoid intercostal nerve injury owing to aggressive manipulation of the scopes and instruments. The pain associated with VATS is not significantly different to that of thoracotomy[115] and there are conflicting differences in the incidence of PTPS [113, 114]. It is unclear if patients with preventative analgesia by way of thoracic epidural analgesia have fewer propensities to develop PTPS [114]. Other regional techniques have not yet been studied in this capacity [114]. There is also conflicting evidence of the causality of acute pain on PTPS [114].

There are many modalities of postoperative pain control that will be briefly explained here.

#### **4.2. Systemic analgesics**

Opioids have a long-standing history of providing effective pain relief. It is the unwanted sideeffects that discourage their use including: nausea, vomiting, respiratory depression, ileus, biliary spasms, urinary retention, sedation, and pruritis. Opioids can be given by many routes – oral, intravenous, intramuscular, transdermal, transmucosal. Intravenous patient controlled analgesia (PCA) allows for increased safety, less opioid use, ability to titrate to individual needs, and some increase in patient satisfaction [116]. Using opioids alone may lead to intolerable side effects, which has led to the concomitant use of other drug classes for their synergistic effects.

Ketamine is an *N*-methyl-D-aspartate (NMDA) antagonist that has direct spinal effects as well as depresses the thalamus and activates the limbic system. It acts at the phencyclidine binding site and has been used as an induction agent. At lower doses, it provides effective analgesia. The use of low dose intraoperative ketamine offers decreased postoperative pain and mor‐ phine consumption [117, 118].

feared complication of epidural analgesia. Nerve injury is usually transient and may occur from direct trauma to the nerves or spinal cord during needle insertion. A more devastating nerve injury can result from an epidural hematoma or abscess. Spinal hematoma occurs very rarely, approximately less than 1 in 150,000 [88]. Although rare, if it is not detected and treated promptly, it leads to irreversible paraplegia. The occurrence of hematoma has been on the rise, whether it is from increased coexistence of anticoagulation and regional anesthesia technique or from increased reporting [123]. Infection can occur from ineffective sterile preparation, contaminated drugs, an underlying infection, or bacteremia. Any of these sources can cause an infection at the insertion site or lead to spread of infection from the skin along the indwelling catheter into the epidural space causing meningitis (if the dura was punctured) or abscess

Anesthesia for Thoracic Surgical Procedures http://dx.doi.org/10.5772/56104 29

Effects related to epidural injection of local anesthetic are usually dose related and include hypotension, motor block, systemic toxicity, and urinary retention. Epidural opioid adminis‐ tration may result in adverse effects that are similar to their parenteral administration. These include pruritis, nausea, urinary retention, decreased arousability, ileus, and respiratory depression. Respiratory depression is the most concerning of the adverse effects and thus necessitates a monitored setting. After epidural injection, in the following 2-4 hours, early respiratory depression can occur which is likely due to the systemic absorption of the opioid [124]. Some opioids are more hydrophilic than others and have a tendency to remain in the CSF causing possible spread and delayed respiratory depression (usually occurs after 4 hours).

Relative contraindications to epidural include sepsis or bacteremia, infection at the insertion site, hypovolemia or shock, coagulopathy or thrombocytopenia, increased intracranial pressure (for risk of brain herniation if accidental dural puncture). One should use caution with patients who have underlying neurological diseases as not to confuse effects of the epidural versus pre-existing neurological deficits. The only absolute contraindication to

TPVB involves injecting local anesthetic into the space adjacent to the thoracic vertebrae, which contains the spinal intercostal nerves. The boundaries of the space include the parietal pleura anterolaterally, the superior costotransverse ligament posteriorly, and medially by a portion of the vertebral body, intervertebral disc and intervertebral foramen [125]. The paravertebral space is continuous with the epidural space, intercostal space, and contralateral paravertebral space (by way of the prevertebral and epidural spaces). The caudal boundary of the space is at the origin of the psoas, while the cranial boundary is unknown. Cranially, radiographic dye has been noted after a thoracic paravertebral injection in the cervical area [126]. The intercostal nerves, dorsal rami, sympathetic chain and associated vessels lie within the fat of the para‐ vertebral space [126]. A percutaneous technique is classically described whereby a needle is inserted into the space until a subtle loss of resistance is met followed by aspiration to ensure that the lung or pleura has not been breached before injecting small amounts of local anesthetic or insertion of a catheter [125]. The injection of local anesthetic can also be performed under

direct visualization by the surgeon prior to the closure of the chest wall.

which could ultimately result in cord compression [123].

epidural placement is patient refusal [88].

**4.4. Thoracic paravertebral nerve block**

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit conversion of arachidonic acid to prostaglandin E2 in inflamed areas via cyclooxygenase (COX). It is suggested that the maxi‐ mum daily dose of NSAIDs should be given/ordered because small doses of NSAIDs are not useful in acute pain relief [118]. When given in conjunction with opioids, NSAIDs reduced the postoperative opioid utilization and decreased unwanted opioid side effects [118]. NSAIDs should be used cautiously in those susceptible to its side effects including risk of renal injury, bleeding and peptic ulcers, asthma and bronchospasm. COX-2 selective inhibitors were developed to avoid the unwanted side effects of NSAIDs and may play a role as an adjunct in postoperative pain control.

#### **4.3. Thoracic epidural**

Thoracic epidural refers to analgesic technique of injecting medication into the epidural space, the potential space that surrounds the spinal cord. A segmental block results with coverage both above and below the injection site. A single injection into the epidural space may be performed, or a catheter may be inserted for prolonged infusion. For post-thoracotomy pain relief, commonly a catheter is inserted via midline or paramedian technique in order to provide intermittent boluses as well as a continuous infusion for pain control. Infusions usually consist of a local anesthetic, an opioid, or a mixture of the two in order to optimize their synergistic effects [119] while reducing the individual doses and side effects [119, 120]. As the nerve roots leave the foramen and become peripheral nerves, they cross through the epidural space where they are bathed in the epidural solution.

The mechanism of action differs between local anesthetics and opioids. Local anesthetics block sodium channels ultimately leading to blocked nerve conduction. The density of local anesthetic blockade is primarily dependent on the concentration of local anesthetic present, and dermatomal spread of blockade is dependent on the volume infused. Also remember that the level of somatic block may be smaller than the sympathetic block because the somatic fibers are less sensitive [121]. Opioids bind to presynaptic and postsynaptic opioid receptors in the substantia gelatinosa, which inhibits the presynaptic release and postsynaptic response to neurotransmitters [121]. In a systemic review of randomized trials, Joshi et al. found that patients with thoracic epidural analgesia had a significantly lower pain scores and needed less supplemental analgesia compared to systemic opioid analgesia [122].

Adverse effects may be from various aspects of epidural placement. Those associated with needle and catheter placement include back pain, inadvertent dural puncture, post dural puncture headache, trauma to spinal cord or nerves, and neuropathy (usually transient). Dural puncture may lead to post dural puncture headache. The headache is usually characterized by severe fronto-occipital pain with head elevation that subsides, sometimes completely, upon return to the supine position [88]. The loss of CSF through the small puncture site may be enough to cause traction on the brain causing pain. Most patients' symptoms completely resolve after a few days to a week. Those that are not able or not willing to wait for spontaneous resolution may opt to undergo an epidural blood patch. Neurologic injury may be the most feared complication of epidural analgesia. Nerve injury is usually transient and may occur from direct trauma to the nerves or spinal cord during needle insertion. A more devastating nerve injury can result from an epidural hematoma or abscess. Spinal hematoma occurs very rarely, approximately less than 1 in 150,000 [88]. Although rare, if it is not detected and treated promptly, it leads to irreversible paraplegia. The occurrence of hematoma has been on the rise, whether it is from increased coexistence of anticoagulation and regional anesthesia technique or from increased reporting [123]. Infection can occur from ineffective sterile preparation, contaminated drugs, an underlying infection, or bacteremia. Any of these sources can cause an infection at the insertion site or lead to spread of infection from the skin along the indwelling catheter into the epidural space causing meningitis (if the dura was punctured) or abscess which could ultimately result in cord compression [123].

Effects related to epidural injection of local anesthetic are usually dose related and include hypotension, motor block, systemic toxicity, and urinary retention. Epidural opioid adminis‐ tration may result in adverse effects that are similar to their parenteral administration. These include pruritis, nausea, urinary retention, decreased arousability, ileus, and respiratory depression. Respiratory depression is the most concerning of the adverse effects and thus necessitates a monitored setting. After epidural injection, in the following 2-4 hours, early respiratory depression can occur which is likely due to the systemic absorption of the opioid [124]. Some opioids are more hydrophilic than others and have a tendency to remain in the CSF causing possible spread and delayed respiratory depression (usually occurs after 4 hours).

Relative contraindications to epidural include sepsis or bacteremia, infection at the insertion site, hypovolemia or shock, coagulopathy or thrombocytopenia, increased intracranial pressure (for risk of brain herniation if accidental dural puncture). One should use caution with patients who have underlying neurological diseases as not to confuse effects of the epidural versus pre-existing neurological deficits. The only absolute contraindication to epidural placement is patient refusal [88].

#### **4.4. Thoracic paravertebral nerve block**

The use of low dose intraoperative ketamine offers decreased postoperative pain and mor‐

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit conversion of arachidonic acid to prostaglandin E2 in inflamed areas via cyclooxygenase (COX). It is suggested that the maxi‐ mum daily dose of NSAIDs should be given/ordered because small doses of NSAIDs are not useful in acute pain relief [118]. When given in conjunction with opioids, NSAIDs reduced the postoperative opioid utilization and decreased unwanted opioid side effects [118]. NSAIDs should be used cautiously in those susceptible to its side effects including risk of renal injury, bleeding and peptic ulcers, asthma and bronchospasm. COX-2 selective inhibitors were developed to avoid the unwanted side effects of NSAIDs and may play a role as an adjunct in

Thoracic epidural refers to analgesic technique of injecting medication into the epidural space, the potential space that surrounds the spinal cord. A segmental block results with coverage both above and below the injection site. A single injection into the epidural space may be performed, or a catheter may be inserted for prolonged infusion. For post-thoracotomy pain relief, commonly a catheter is inserted via midline or paramedian technique in order to provide intermittent boluses as well as a continuous infusion for pain control. Infusions usually consist of a local anesthetic, an opioid, or a mixture of the two in order to optimize their synergistic effects [119] while reducing the individual doses and side effects [119, 120]. As the nerve roots leave the foramen and become peripheral nerves, they cross through the epidural space where

The mechanism of action differs between local anesthetics and opioids. Local anesthetics block sodium channels ultimately leading to blocked nerve conduction. The density of local anesthetic blockade is primarily dependent on the concentration of local anesthetic present, and dermatomal spread of blockade is dependent on the volume infused. Also remember that the level of somatic block may be smaller than the sympathetic block because the somatic fibers are less sensitive [121]. Opioids bind to presynaptic and postsynaptic opioid receptors in the substantia gelatinosa, which inhibits the presynaptic release and postsynaptic response to neurotransmitters [121]. In a systemic review of randomized trials, Joshi et al. found that patients with thoracic epidural analgesia had a significantly lower pain scores and needed less

Adverse effects may be from various aspects of epidural placement. Those associated with needle and catheter placement include back pain, inadvertent dural puncture, post dural puncture headache, trauma to spinal cord or nerves, and neuropathy (usually transient). Dural puncture may lead to post dural puncture headache. The headache is usually characterized by severe fronto-occipital pain with head elevation that subsides, sometimes completely, upon return to the supine position [88]. The loss of CSF through the small puncture site may be enough to cause traction on the brain causing pain. Most patients' symptoms completely resolve after a few days to a week. Those that are not able or not willing to wait for spontaneous resolution may opt to undergo an epidural blood patch. Neurologic injury may be the most

supplemental analgesia compared to systemic opioid analgesia [122].

phine consumption [117, 118].

28 Principles and Practice of Cardiothoracic Surgery

postoperative pain control.

they are bathed in the epidural solution.

**4.3. Thoracic epidural**

TPVB involves injecting local anesthetic into the space adjacent to the thoracic vertebrae, which contains the spinal intercostal nerves. The boundaries of the space include the parietal pleura anterolaterally, the superior costotransverse ligament posteriorly, and medially by a portion of the vertebral body, intervertebral disc and intervertebral foramen [125]. The paravertebral space is continuous with the epidural space, intercostal space, and contralateral paravertebral space (by way of the prevertebral and epidural spaces). The caudal boundary of the space is at the origin of the psoas, while the cranial boundary is unknown. Cranially, radiographic dye has been noted after a thoracic paravertebral injection in the cervical area [126]. The intercostal nerves, dorsal rami, sympathetic chain and associated vessels lie within the fat of the para‐ vertebral space [126]. A percutaneous technique is classically described whereby a needle is inserted into the space until a subtle loss of resistance is met followed by aspiration to ensure that the lung or pleura has not been breached before injecting small amounts of local anesthetic or insertion of a catheter [125]. The injection of local anesthetic can also be performed under direct visualization by the surgeon prior to the closure of the chest wall.

Injection of local anesthetic into the paravertebral space can give varying degrees of analgesia. The injection may remain localized to the area of injection producing a single level ipisilateral block, or it can spread to the above and below adjacent levels, as well as to the epidural space and contralateral paravertebral space. For example, Eason found that a single injection of 15ml of 0.375% bupivacaine spread over 4 spaces [125]. Similarly, 15ml of 0.5% bupivacaine injection led to a unilateral 5 level dermatome somatic block and 8 level sympathetic block [127].

ral pocket, and a catheter can be introduced percutaneously into the space. After closure of the thoracotomy, an infusion of local anesthetic will fill the extrapleural space which leads to an intercostal block. Interpleural catheters can be inserted percutaneously to attain an intercostal nerve block, but one must keep in mind that a large volume of the anesthet‐ ic may be lost to the chest tubes. Interpleural anesthesia requires diffusion across the pleura and sub pleural space in order to attain an intercostal nerve blockade. Single shot direct intercostal nerve block appears to have the same or superior pain control compared to epidural on the day of surgery, but after the effects of the local anesthesia have been exhausted, epidural anesthesia is superior to intercostal nerve block [131-133] Detterbeck states that extrapleural infusion of local anesthetic is more effective than systemic narcot‐ ics, and at least as good as thoracic epidural. Extrapleural intercostal nerve block pro‐ vides a unilateral blockade, so the amount of urinary retention and hypotension are decreased, and there is not a need for special monitoring because the risk of respiratory depression is minimal [131]. Pain relief from interpleural infusion is inconsistent [131].

Anesthesia for Thoracic Surgical Procedures http://dx.doi.org/10.5772/56104 31

Systemic absorption of local anesthetic is notoriously high for intercostal nerve block due to the vascularity of the area of injection. There are no specific absolute contraindications to intercostal nerve blocks. They should be avoided in patients in whom high systemic levels of

Wound infiltration with local anesthetic targets the peripheral level of pain, and has been used widely in minor surgical procedures [134, 135]. The relatively short-term duration of the local infiltration limits the usefulness of one-time wound infiltration for more major thoracic surgery. An elastomeric pump connected to a multi orifice catheter allows for continuous local anesthetic incisional infusion. Implementation of this technique is quite simple, with a minimal technical failure incidence [116]. A catheter is threaded in or near the insult and connected to a reservoir pump of local anesthetic by way of a flow-limiting valve. The surrounding tissues are then continuously bathed in the local anesthetic at 4ml/hr. By providing anesthesia at the site of insult there may be less need for systemic narcotics, and avoid many systemic narcotic effects including postoperative nausea and vomiting. It is also believed that local anesthetic at the wound site can decrease the local inflammatory response which may in turn decrease pain and hyperalgesia [116]. Wheatley et al found that using an elastomeric pump is a safe and effective adjunct for post-thoracotomy pain relief. Also, patients had lower pain scores and decreased narcotic need when compared to thoracic epidural analgesia alone [136]. Although local anesthetic toxicity is always a concern with infusions, the incidence of systemic toxicity is low [116]. Wound infiltration is safe and not associated with increased acute wound-related

Hemorrhagic complications from neuraxial blockade are of great concern. Epidural analgesia is usually not initiated in patients who have a preexisting coagulopathy. The following are

local anesthetics will not be well tolerated such as those with seizure disorders.

complications or long-term effects on wound healing [137].

**4.6. Elastomeric pumps**

**4.7. Anticoagulation**

Advantages of TPVB are many. TPVB is easy to learn and has a high success rate [126]. Successful placement of TPVB also can eliminate some unwanted effects of epidural analgesia such as spinal cord injury, spinal hematoma, excessive hypotension (owing to only a unilateral sympathetic blockade), and urinary retention [128]. Also, the nursing care required after TPVB is no different than normal post-surgical care [129]. A meta-analysis identified TPVB as having equivalent pain relief after thoracic surgery with less major side effects and decreased pulmonary complications to that of epidural analgesia [130].

Adverse effects of TPVB include accidental pleural puncture, which could lead to a pneumo‐ thorax. The incidence of puncture and pneumothorax are 0.8% and 0.5% respectively, which is similar to other anesthetic procedures with pneumothorax risk [128]. Other adverse effects include relative hypotension, failed block, and vascular puncture.

Contraindications to TPVB are similar to those of epidural placement including infection at the insertion site, bacteremia, epyema. Another relative contraindication would be if the patient has had a previous thoracotomy because the ipsilateral paravertebral space may have been altered or obliterated as a result of surgery [124]. With respect to anticoagulation, the paravertebral space is less vascular than the epidural space, and paravertebral vessel puncture is less common [128, 129].

#### **4.5. Intercostal nerve block**

The intercostal nerve provides sensory and motor innervation to chest wall and is found in the costal groove of each rib. Intercostal nerve blockade provides unilateral sensory and motor anesthesia to these areas. Local anesthetic is commonly injected 5 to 7 cm from the midline over several sections owing to the great deal of overlap between the intercostal nerves. There are different approaches to intercostal nerve blocks for thoracic procedures. The simplest is to inject local anesthetic around several intercostal nerves during thoracotomy when the chest wall is open. Cryotherapy, continuous infusion or successive boluses of local anesthetic are also options [131].

Direct intercostal nerve block is most easily done by direct visualization during thoracoto‐ my, but can also be done percutaneously. Local is injected over multiple segments inferior to the rib with caution to avoid intravascular injection. Usually a small amount (2-5ml) of local is injected two to three spaces above and below the incision [131]. Cryoanalgesia interrupts nerve conduction for 1 to 3 months as a result of the freezing and subsequent damage of the myelin sheath [131] and is associated with long term intercostal neuralgia [132]. Extrapleural and interpleural infusion of local anesthetic are also techniques to block the intercostal nerves. Peeling back the pleura from the chest wall can create an extrapleu‐

ral pocket, and a catheter can be introduced percutaneously into the space. After closure of the thoracotomy, an infusion of local anesthetic will fill the extrapleural space which leads to an intercostal block. Interpleural catheters can be inserted percutaneously to attain an intercostal nerve block, but one must keep in mind that a large volume of the anesthet‐ ic may be lost to the chest tubes. Interpleural anesthesia requires diffusion across the pleura and sub pleural space in order to attain an intercostal nerve blockade. Single shot direct intercostal nerve block appears to have the same or superior pain control compared to epidural on the day of surgery, but after the effects of the local anesthesia have been exhausted, epidural anesthesia is superior to intercostal nerve block [131-133] Detterbeck states that extrapleural infusion of local anesthetic is more effective than systemic narcot‐ ics, and at least as good as thoracic epidural. Extrapleural intercostal nerve block pro‐ vides a unilateral blockade, so the amount of urinary retention and hypotension are decreased, and there is not a need for special monitoring because the risk of respiratory depression is minimal [131]. Pain relief from interpleural infusion is inconsistent [131].

Systemic absorption of local anesthetic is notoriously high for intercostal nerve block due to the vascularity of the area of injection. There are no specific absolute contraindications to intercostal nerve blocks. They should be avoided in patients in whom high systemic levels of local anesthetics will not be well tolerated such as those with seizure disorders.

#### **4.6. Elastomeric pumps**

Injection of local anesthetic into the paravertebral space can give varying degrees of analgesia. The injection may remain localized to the area of injection producing a single level ipisilateral block, or it can spread to the above and below adjacent levels, as well as to the epidural space and contralateral paravertebral space. For example, Eason found that a single injection of 15ml of 0.375% bupivacaine spread over 4 spaces [125]. Similarly, 15ml of 0.5% bupivacaine injection led to a unilateral 5 level dermatome somatic block and 8 level sympathetic block [127].

Advantages of TPVB are many. TPVB is easy to learn and has a high success rate [126]. Successful placement of TPVB also can eliminate some unwanted effects of epidural analgesia such as spinal cord injury, spinal hematoma, excessive hypotension (owing to only a unilateral sympathetic blockade), and urinary retention [128]. Also, the nursing care required after TPVB is no different than normal post-surgical care [129]. A meta-analysis identified TPVB as having equivalent pain relief after thoracic surgery with less major side effects and decreased

Adverse effects of TPVB include accidental pleural puncture, which could lead to a pneumo‐ thorax. The incidence of puncture and pneumothorax are 0.8% and 0.5% respectively, which is similar to other anesthetic procedures with pneumothorax risk [128]. Other adverse effects

Contraindications to TPVB are similar to those of epidural placement including infection at the insertion site, bacteremia, epyema. Another relative contraindication would be if the patient has had a previous thoracotomy because the ipsilateral paravertebral space may have been altered or obliterated as a result of surgery [124]. With respect to anticoagulation, the paravertebral space is less vascular than the epidural space, and paravertebral vessel puncture

The intercostal nerve provides sensory and motor innervation to chest wall and is found in the costal groove of each rib. Intercostal nerve blockade provides unilateral sensory and motor anesthesia to these areas. Local anesthetic is commonly injected 5 to 7 cm from the midline over several sections owing to the great deal of overlap between the intercostal nerves. There are different approaches to intercostal nerve blocks for thoracic procedures. The simplest is to inject local anesthetic around several intercostal nerves during thoracotomy when the chest wall is open. Cryotherapy, continuous infusion or successive boluses of local anesthetic are

Direct intercostal nerve block is most easily done by direct visualization during thoracoto‐ my, but can also be done percutaneously. Local is injected over multiple segments inferior to the rib with caution to avoid intravascular injection. Usually a small amount (2-5ml) of local is injected two to three spaces above and below the incision [131]. Cryoanalgesia interrupts nerve conduction for 1 to 3 months as a result of the freezing and subsequent damage of the myelin sheath [131] and is associated with long term intercostal neuralgia [132]. Extrapleural and interpleural infusion of local anesthetic are also techniques to block the intercostal nerves. Peeling back the pleura from the chest wall can create an extrapleu‐

pulmonary complications to that of epidural analgesia [130].

include relative hypotension, failed block, and vascular puncture.

is less common [128, 129].

30 Principles and Practice of Cardiothoracic Surgery

**4.5. Intercostal nerve block**

also options [131].

Wound infiltration with local anesthetic targets the peripheral level of pain, and has been used widely in minor surgical procedures [134, 135]. The relatively short-term duration of the local infiltration limits the usefulness of one-time wound infiltration for more major thoracic surgery. An elastomeric pump connected to a multi orifice catheter allows for continuous local anesthetic incisional infusion. Implementation of this technique is quite simple, with a minimal technical failure incidence [116]. A catheter is threaded in or near the insult and connected to a reservoir pump of local anesthetic by way of a flow-limiting valve. The surrounding tissues are then continuously bathed in the local anesthetic at 4ml/hr. By providing anesthesia at the site of insult there may be less need for systemic narcotics, and avoid many systemic narcotic effects including postoperative nausea and vomiting. It is also believed that local anesthetic at the wound site can decrease the local inflammatory response which may in turn decrease pain and hyperalgesia [116]. Wheatley et al found that using an elastomeric pump is a safe and effective adjunct for post-thoracotomy pain relief. Also, patients had lower pain scores and decreased narcotic need when compared to thoracic epidural analgesia alone [136]. Although local anesthetic toxicity is always a concern with infusions, the incidence of systemic toxicity is low [116]. Wound infiltration is safe and not associated with increased acute wound-related complications or long-term effects on wound healing [137].

#### **4.7. Anticoagulation**

Hemorrhagic complications from neuraxial blockade are of great concern. Epidural analgesia is usually not initiated in patients who have a preexisting coagulopathy. The following are some consensus guidelines assembled by the American Society of Regional Anesthesia and Pain Medicine [138]:

**•** Twice daily doses should not be initiated with an indwelling catheter, and must be removed

Anesthesia for Thoracic Surgical Procedures http://dx.doi.org/10.5772/56104 33

**•** Once-daily dosing – may start 6-8 hours postoperatively, the catheter can be maintained,

**•** If initial does of warfarin is given more than 24 hours prior to surgery, INR should be

**•** If low-dose warfarin therapy is ongoing during epidural anesthesia, neurological evalua‐

**•** Catheters should be removed when INR is less than 1.5, and neurological assessment should

**•** NSAIDs have no specific concerns or added risk with epidural with or without catheter

**•** The risk of bleeding with clopidogrel, ticlopidine, and GP IIB/IIIA inhibitors is not known.

**•** 7 and 14 days should elapse between discontinuation of ticlopidine and clopidogre,

**•** Platelet function normalization must occur before placement of neuraxial block if discon‐

**•** Epidural catheters should not be maintained while on GP IIB/IIIA inhibitor therapy

before the first dose

removal after 10-12 hours of last dose

**•** INR should be normalized prior to neuraxial technique

**•** If 1.5 < INR < 3, catheters should be cautiously removed

placement, unless concurrent medications affecting clotting

respectively, and placement of neuraxial block

**•** They do not create risk that impedes with neuraxial block

**•** Garlic inhibits platelet aggregation, increases fibrinolysis

**•** Ginko inhibits platelet-activating factor

**•** Ginseng has the potential to inhibit coagulation

**•** Anticoagulation effect present for 1-3 hours

**•** There are no pharmacologic reversals

**•** If the INR is more than 3, the dose of warfarin should be held/reduced

**4.** Oral Anticoagulants – Warfarin

checked prior to neuraxial block

be continued for 24 hours

**5.** Antiplatelet Medications

tinued for only 5-7 days

**7.** Thrombin inhibitors **•** Monitored by aPTTT

**6.** Herbals

tions and daily INR checks are advised


some consensus guidelines assembled by the American Society of Regional Anesthesia and

**•** It is not clear how long to wait after thrombolytic therapy for safe performance of neuraxial

**•** If neuraxial block is at or near time of thrombolytic therapy neurologic checks should be

**•** There is no recommendation for removal of neuraxial catheters in unexpected thrombolytic

**•** Placement of the block prior to therapy may be desirable although increased risk is not

**•** In twice-daily doses – epidurals may be placed before the next scheduled dose, the catheter can coexist with regimen, and preferably the catheter can be removed one hour prior to next

**•** Thrice daily doses or more than 10,000units unfractionated heparin – there is no data published, but it is advised not to maintain an epidural catheter with this regimen

**•** If the patient has received more than four days of heparin, a platelet count should be obtained prior to block or removal of catheter in the instace of heparin induced thrombo‐

**•** Wait 2-4 hours after heparin to remove cathers, resume therapy one hours after removal of

**•** Bloody placement may increase risk of hematoma, but the case does not necessarily need to

**•** A bloody placement does not mandate cancellation of the case, however LMWH should be

**•** If the patient is on higher dose LMWH, one should wait 24 hours to place epidural

**•** Do not place epidural at 2 hours after dose – peak anticoagulation activity

Pain Medicine [138]:

anesthesia,

therapy

dose

cytopenia

catheter

be cancelled.

delayed for 24 hours

**3.** Low-Molecular Weight Heparin

**1.** Thrombolytic therapy

32 Principles and Practice of Cardiothoracic Surgery

none no less than every 2 hours,

**2.** Subcutaneous unfractionated heparin

**•** There is little risk of spinal hematoma

**•** Avoid thrombolytic for 10 days after neuraxial puncture,

**•** Review of other medications that may affect clotting is advised

demonstrated in the presence of subcutaneous heparin

**•** After needle placement, wait one hour to administer heparin

**•** Epidural placement should happen 10-12 hours after last does

