Anesthesia In Thoracic Surgery: Changes Of Para...

Bilateral symmetric anesthesia due to extensive epidural spread or unintentional intrathecal injection into a dural sleeve may occur, particularly when the needle is directed medially or when a larger volume of local anesthetic (>25 mL) is used. For this reason, patients should be monitored using the same vigilance and methods as those employed for injection using the large-volume, single-injection epidural technique. The ipsilateral ilioinguinal and iliohypogastric nerves may also occasionally be involved after lower thoracic paravertebral injections. This is either due to epidural spread or extended subendothoracic fascial spread to the retroperitoneal space where the lumbar spinal nerves are located. The effect of gravity on the dermatomal spread of anesthesia after TPVB is unknown, but there may be a tendency for preferential pooling of injected solution toward the dependent levels.

Anesthesia in Thoracic Surgery: Changes of Para...

It is preferable to perform TPVB with the patient in the sitting position because the surface anatomy is better visualized and patients are often more comfortable. However, when this is not possible or practical, TPVB can also be performed with the patient in the lateral, or prone position. The number and levels of injections are selected according to the desired spread of local anesthesia. In this example, description of the TPVB for breast surgery is described. Surface landmarks are identified and marked with a skin marker before block placement (Figure 6). Skin markings are also made 2.5 cm lateral to the midline at the thoracic levels that are to be blocked.

TABLE 1. Indications for thoracic paravertebral block.AnesthesiaBreast surgeryHerniorrhaphy (thoracolumbar anesthesia)Chest wound explorationPostoperative Analgesia (as part of a balanced analgesic regimen)ThoracotomyThoracoabdominal esophageal surgeryVideo-assisted thoracoscopic surgeryCholecystectomyRenal surgeryBreast surgeryHerniorrhaphyLiver resectionAppendicectomyMinimally invasive cardiac surgeryConventional cardiac surgery (bilateral TPVB)Chronic Pain ManagementBenign and malignant neuralgiaMiscellaneousPostherpetic neuralgiaRelief of pleuritic chest painMultiple fractured ribsTreatment of hyperhydrosisLiver capsule pain after blunt abdominal traumaAbbreviation: TPVB, thoracic paravertebral block.

Lumbar paravertebral block (LPVB) is technically similar to a TPVB but due to differences in anatomy between the thoracic and lumbar paravertebral spaces the two paravertebral techniques are described separately. LPVB is used most commonly in combination with a TPVB, as a thoracolumbar paravertebral block, for surgical anesthesia during inguinal herniorrhaphy.

The most commonly administered block of the paraxial nervous system used to be paravertebral block (PVB). Although the anatomy of paravertebral space was known for many years, reproducible successful PVB became achievable routinely only recently due to the ability of the operator to locate the paravertebral space and avoid damaging the pleura.[5] Similarly, providing muscular plane blocks (such as serratus anterior plane [SAP] block and erector spinae block [ESB]) and selective nerve blocks (pectoralis nerve) would have been difficult without visualizing the muscular plane/nerve by ultrasound. PVB became a viable option to thoracic epidural anesthesia because it was paraxial but benefits such as epidural were observed. In addition, the disadvantages of thoracic epidural such as hemodynamic instability were not noted with continuous PVB.[6]

There is controversy about epidural spread and its contribution to the extension of TPVB. Radioopaque contrast medium infused postoperatively through an extrapleural paravertebral catheter placed intraoperatively under direct vision remains confined to the paravertebral space. 8,67In contrast, varying degrees of epidural spread has been shown to occur after 70% of percutaneous paravertebral injections, 46which is mostly unilateral, 46and the volume involved is considered too small to produce clinically significant epidural block. 68Cadaveric dissection also confirms that only a small proportion of the injectate enters the epidural space 42and remains confined to the side of injection. The vertebral attachment of the endothoracic fascia attenuates prevertebral spread 36,40and may also influence epidural spread or mass movement of drug after an extrapleural paravertebral compartment injection. Clinically, sensory anesthesia is predominantly ipsilateral and greater after epidural spread than after only paravertebral spread. 46Current evidence therefore suggests that ipsilateral epidural spread of discrete amounts of local anesthetic occurs after thoracic paravertebral injection, which contributes to the extension of a TPVB.

Thoracic paravertebral block offers several technical and clinical advantages (table 1) and is indicated for anesthesia and analgesia when the afferent pain input is predominantly unilateral from the chest and abdomen. Reported indications are listed in table 2. Bilateral TPVB has also been used perioperatively during thoracic, 12,15major abdominal vascular, 13and breast 11,16surgeries.

This section presents common and controversial indications for the use of lumbar and thoracic epidural block in lower extremity, genitourinary, vascular, gynecologic, colorectal, and cardiothoracic surgery. It also reviews less common and novel indications for epidural anesthesia and analgesia, including for the treatment of patients with sepsis and uncommon medical disorders (Table 1).

The benefits of and indications for thoracic epidural anesthesia (TEA) are expanding (Table 7). TEA offers superior perioperative analgesia compared with systemic opioids, decreases postoperative pulmonary complications, decreases the duration of postoperative ileus, and decreases mortality in patients with multiple rib fractures, among other things. This section explores the role of TEA as either a primary anesthetic or as an adjuvant to GA for cardiac, thoracic, abdominal, colorectal, genitourinary, and gynecologic surgery (Figure 1). It also reviews the expanding role of TEA for video-assisted thoracic surgery (VATS) and laparoscopic surgery.TABLE 7. Benefits of thoracic epidural anesthesia and analgesia.Improved perioperative analgesia compared with othermodalitiesDecreased postoperative pulmonary complicationsDecreased duration of postoperative ileusDecreased duration of mechanical ventilationDecreased mortality in patients with rib fractures

Upper abdominal surgeries that can be performed with epidural anesthesia and analgesia include esophagectomy, gastrectomy, pancreatectomy, hepatic resection, and cholecystectomy. Laparoscopic cholecystectomy with epidural block30 and distal gastrectomy with a combined general-epidural anesthetic have also been reported. Midthoracic epidural catheter placement with segmental block extending from T5 (T4 for laparoscopic surgery) to T8 is appropriate for most upper abdominal procedures and, due to lumbar and sacral nerve root sparing, has minimal risk of lower extremity motor deficits, urinary retention, hypotension, and other sequelae of lumbar epidural anesthesia.

Open prostate surgery, radical cystectomy and urinary diversion, and simple, partial, and radical nephrectomy can be performed under neuraxial block, either alone or in combination with GA, depending on the procedure. Some potential advantages of neuraxial compared with GA for radical retropubic prostatectomy include decreased intraoperative blood loss and transfusions, a decreased incidence of postoperative thromboembolic events, improved analgesia and level of activity up to 9 weeks postoperatively, faster return of bowel function, and several other still-disputed advantages of neuraxial anesthesia, such as faster time to hospital discharge and reduced hospital costs. For the open procedure, patients may require generous sedation in the absence of a combined general-neuraxial technique. A T6 sensory level is required, with catheter placement in the midthoracic region. Radical cystectomy is performed on patients with invasive bladder cancer and may have improved outcomes with a combined general-epidural anesthetic compared to GA alone.

Open and laparoscopic colectomy, sigmoidectomy, and appendectomy are among other lower abdominal surgeries that can be performed under neuraxial anesthesia, with or without GA. Of particular interest in patients undergoing bowel surgery thoracic epidural block decreases the duration of postoperative ileus, possibly without affecting anastomotic healing and leakage. The superior postoperative analgesia associated with continuous epidural infusions, with or without opioids, most likely improves postoperative lung function in patients undergoing gastrointestinal (GI) surgery, although specific randomized controlled trials have not been conducted. In combination with early feeding and ambulation, TEA plays a role in early hospital discharge after certain GI surgeries. A similar outcome has been demonstrated after laparoscopic colonic resection, followed by epidural analgesia for 2 days and early oral nutrition and mobilization (ie, multimodal rehabilitation). Epidural catheter placement between T9 and T11 is usually appropriate for lower abdominal procedures; a sensory block extending to T7 or T9 is required for most colonic surgeries (sigmoid resection, ileotransversostomy, hemicolectomy).

Pediatric SurgeryThere is a considerable body of literature dedicated to the use of regional anesthesia for pediatric surgery in both the inpatient and the ambulatory settings. Advantages of neuraxial block for the pediatric population include optimal postoperative analgesia, which is particularly important in extensive scoliosis repair, repair of pectus excavatum, and major abdominal and thoracic procedures; decreased GA requirements; earlier awakening; and earlier discharge in the ambulatory setting. Certain subsets of pediatric patients, such as those with cystic fibrosis, a family history of MH, or a history of prematurity, also benefit from the use of neuraxial anesthesia in lieu of GA. However, parental refusal, concerns about performing regional nerve blocks in anesthetized patients, and airway concerns in patients with limited oxygen reserves pose challenges to the routine use of neuraxial block in this patient population. 041b061a72