Mark A. Chaney

Intrathecal and Epidural Anesthesia and Analgesia for Cardiac Surgery

Adequate postoperative analgesia prevents unnecessary patient discomfort. It may also decrease morbidity, postoperative hospital length of stay and, thus, cost. Achieving optimal pain relief after cardiac surgery is often difficult. Many techniques are available, and all have specific advantages and disadvantages. Intrathecal and epidural techniques clearly produce reliable analgesia in patients undergoing cardiac surgery. Additional potential benefits include stress response attenuation and thoracic cardiac sympathectomy. The quality of analgesia obtained with thoracic epidural anesthetic techniques is sufficient to allow cardiac surgery to be performed in awake patients without general endotracheal anesthesia. However, applying regional anesthetic techniques to patients undergoing cardiac surgery is not without risk. Side effects of local anesthetics (hypotension) and opioids (pruritus, nausea/vomiting, urinary retention, and respiratory depression), when used in this manner, may complicate perioperative management. Increased risk of hematoma formation in this scenario has generated much of lively debate regarding the acceptable risk-benefit ratio of applying regional anesthetic techniques to patients undergoing cardiac surgery.

Pulmonary effects of methylprednisolone in patients undergoing coronary artery bypass grafting and early tracheal extubation

Numerous clinical studies suggest that methylprednisolone may facilitate early tracheal extubation after cardiac surgery, yet no investigation has rigorously examined the use of the drug in this setting.In this prospective, randomized, double-blind, placebo-controlled study, we examined the pulmonary effects of methylprednisolone in patients undergoing coronary artery bypass grafting (CABG) and early tracheal extubation. Sixty patients undergoing elective CABG and early tracheal extubation were randomized into two groups. Group MP patients received IV methylprednisolone (30 mg/kg during sternotomy and 30 mg/kg during initiation of cardiopulmonary bypass) and Group NS patients received IV placebo at the same two times. Perioperative management was standardized. Alveolar-arterial (A-a) oxygen gradient, lung compliance, shunt, and dead space were determined four times perioperatively. Postoperative tracheal extubation was accomplished at the earliest appropriate time. Both groups exhibited significant postoperative increases in A-a oxygen gradient and shunt (P < 0.000001 for each group) and significant postoperative decreases in dynamic lung compliance (P < 0.000001 for each group). Patients in Group MP exhibited significantly larger increases in postoperative A-a oxygen gradient (P = 0.001) and shunt (P = 0.001) compared with patients in Group NS. Postoperative alterations in dynamic lung compliance, static lung compliance, and dead space were not statistically significant between the groups. The time to postoperative tracheal extubation was prolonged in Group MP patients compared with Group NS patients (769 +/- 294 vs 604 +/- 315 min, respectively; P = 0.05). Methylprednisolone was associated with larger increases in postoperative A-a oxygen gradient and shunt, was unable to prevent postoperative decreases in lung compliance, and prolonged extubation time, which indicate that use of the drug may hinder early tracheal extubation in patients after cardiac surgery. Implications: Traditionally, methylprednisolone has been administered to patients undergoing cardiac surgery to decrease postoperative pulmonary dysfunction. This study revealed that the drug is associated with larger increases in postoperative alveolararterial oxygen gradient and shunt and prolonged tracheal extubation time in patients undergoing coronary artery bypass grafting, which indicate that use of the drug may hinder early tracheal extubation. (Anesth Analg 1998;87:27-33)

Intrathecal morphine for coronary artery bypass grafting and early extubation.

Aggressive control of pain during the immediate postoperative period after cardiac surgery with early tracheal extubation may decrease morbidity and mortality.This prospective, randomized, double-blinded, placebo-controlled clinical study examined the use of intrathecal morphine in patients undergoing cardiac surgery and its influence on early tracheal extubation and postoperative analgesic requirements. Patients were randomized to receive either 10 micro g/kg of intrathecal morphine (n = 19) or intrathecal placebo (n = 21). Perioperative anesthetic management was standardized (intravenous (IV) fentanyl, 20 micro g/kg, and IV midazolam, 10 mg) and included postoperative patient-controlled morphine analgesia. Of the patients who were tracheally extubated during the immediate postoperative period, the mean time from intensive care unit arrival to extubation was significantly prolonged in patients who received intrathecal morphine (10.9 h) when compared to patients who received intrathecal placebo (7.6 h). Three patients who received intrathecal morphine had extubation substantially delayed because of prolonged ventilatory depression. Although mean postoperative IV morphine use for 48 h was less in patients who received intrathecal morphine (42.8 mg) when compared to patients who received intrathecal placebo (55.0 mg), the difference between groups was not statistically significant. In conclusion, intrathecal morphine offers promise as a useful adjunct in controlling postoperative pain in patients after cardiac surgery. However, the optimal dose of intrathecal morphine in this setting, along with the optimal intraoperative baseline anesthetic that will provide significant analgesia, yet not delay extubation in the immediate postoperative period, remains to be elucidated. (Anesth Analg 1997;84:241-8)

Large-dose intrathecal morphine for coronary artery bypass grafting.

Aggressive control of pain during the immediate postoperative period after cardiac surgery, associated with decreased blood catecholamine levels, may decrease morbidity and mortality.This study investigated the use of large-dose intrathecal morphine for cardiac surgery and its effect on postoperative analgesic requirements and blood catecholamine levels. Patients were randomized to receive either 4.0 mg of intrathecal morphine (Group MS) or intrathecal saline placebo (Group NS). Perioperative care was standardized and included postoperative patient-controlled analgesia. Arterial blood samples were obtained perioperatively to ascertain catecholamine levels. Patients in Group MS required significantly less postoperative intravenous morphine than patients in Group NS. Although perioperative norepinephrine and epinephrine levels in Group MS patients tended to be lower than Group NS patients, the differences were not statistically significant. In conclusion, large-dose intrathecal morphine initiates reliable postoperative analgesia but does not reliably attenuate the stress response during and after cardiac surgery. (Anesth Analg 1996;83:215-22)

Port-access minimally invasive cardiac surgery increases surgical complexity, increases operating room time, and facilitates early postoperative hospital discharge

Background Proposed advantages of port-access cardiac surgery have yet to be substantiated. The authors retrospectively compared patients undergoing port-access cardiac surgery with a matched group undergoing conventional cardiac surgery. Methods Forty-six patients who underwent port-access cardiac surgery were matched with 46 who underwent conventional cardiac surgery. Absolute criteria for matching included morning-of-surgery admission, procedure undergone, and care being delivered by one of two surgeons. If possible, matching included care delivered by one of two anesthesiologists. Patients were matched as closely as possible for preoperative demographic and clinical characteristics. Results All 46 pairs of patients were matched for procedure and admitted the morning of surgery. All 92 operations were performed by one of two surgeons, and 89% were performed by one of two anesthesiologists. Preoperative demographic and clinical characteristics were equivalent between groups. Compared with conventional cardiac surgery, port-access cardiac surgery increased surgical complexity (it almost tripled cardiopulmonary bypass time during coronary artery bypass grafting and increased it almost 40% during mitral valve procedures) and increased total operating room time (P < 0.0001). Port-access cardiac surgery had no beneficial effect on earlier postoperative extubation, decreased incidence of atrial fibrillation, or intensive care unit time, yet it decreased postoperative duration of stay (P = 0.029, all patients), a benefit observed primarily in patients undergoing coronary artery bypass grafting (P = 0.002). Conclusions This retrospective analysis revealed that port-access cardiac surgery increases surgical complexity, increases operating room time, has no effect on earlier postoperative extubation or decreased incidence of atrial fibrillation or intensive care unit time, and may facilitate postoperative hospital discharge (primarily in patients undergoing coronary artery bypass grafting). Properly designed prospective investigation is necessary to ascertain whether port-access cardiac surgery truly offers any benefits over conventional cardiac surgery.

Cardiac surgery and intrathecal/epidural techniques: at the crossroads?

TILIZATION of intrathecal and epidural anesthesia and analgesia techniques in patients undergoing cardiac surgery has increased. 1,2 Potential benefits include improved postoperative analgesia, attenuation of the stress response to surgery, and induction of thoracic cardiac sympathectomy. These potential clinical benefits may reduce perioperative morbidity and mortality. However, substantial controversy persists regarding the risk:benefit ratio of intrathecal and epidural instrumentation in cardiac surgical patients who subsequently receive perioperative anticoagulation. In this issue of the Journal, Jacobsohn and associates 3 present the findings of their small (n = 43), prospective, randomized, blinded, placebo-controlled clinical study investigating the potential clinical benefits of intrathecal morphine in healthy patients undergoing elective cardiac surgery with cardiopulmonary bypass. The intrathecal injection (morphine or placebo) was administered immediately prior to induction of general anesthesia and perioperative care was appropriately standardized. Extubation times were equivalent between the two groups (approximately 40 min). Patients receiving intrathecal morphine exhibited enhanced postoperative analgesia, as evidenced by decreased morphine requirements and decreased visual analogue pain scores. Both groups exhibited substantial pulmonary dysfunction (per spirometry) during the immediate postoperative period yet dysfunction was less pronounced in the patients receiving intrathecal morphine. Postoperative arterial blood gases and atelectasis scores were equivalent between the two groups, as were analgesic satisfaction, hospital satisfaction, and mean hospital length of stay. Thus, intrathecal morphine provided only enhanced postoperative analgesia (yet no enhancement of analgesic satisfaction). Such findings are not new (similar results have been previously published) yet present an opportunity to critically reassess the current use of intrathecal and epidural techniques in patients undergoing cardiac surgery. Use of intrathecal and epidural techniques in patients undergoing cardiac surgery certainly enhances postoperative analgesia, may attenuate the stress response to surgery, and may induce thoracic cardiac sympathectomy. Because of enhanced flexibility (and more potential clinical benefits), most recent clinical investigations have focused on the use of thoracic epidural techniques. Intrathecal morphine was initially used in patients undergoing cardiac surgery in 1980. Since then, numerous clinical investigations (some prospective, randomized, blinded, placebo-controlled) attest to this technique’s ability to induce reliable postoperative analgesia. However, neither intrathecal opioids or local anesthetics reliably attenuate the stress response associated with cardiac surgery or reliably induce perioperative thoracic cardiac sympathectomy. In contrast to intrathecal techniques, the presence of a catheter in the epidural space allows an almost infinite number of possibilities regarding potential drugs and dosing schedules to obtain specific goals. The initial description of thoracic epidural anesthesia and analgesia applied to a cardiac surgical patient occurred in 1954. Numerous clinical investigations (none well-controlled) attest to the ability of thoracic epidural opioids and local anesthetics to reliably induce postoperative analgesia in patients after cardiac surgery. Administration of thoracic epidural local anesthetics (not opioids) has the potential to attenuate the stress response associated with the perioperative period and

Multivessel beating heart robotic myocardial revascularization increases morbidity and mortality

OBJECTIVE The vast majority of reports describing beating heart robotic myocardial revascularization (total endoscopic coronary artery bypass) contain very small numbers of patients undergoing single-vessel bypass. We present a large series of patients undergoing multivessel total endoscopic coronary artery bypass. METHODS We performed a retrospective clinical review of 106 patients undergoing total endoscopic coronary artery bypass (72% multivessel) at 1 institution by 1 experienced cardiac surgeon/physician assistant team. These results were compared with the expected clinical outcomes from conventional coronary artery bypass grafting calculated using the Society of Thoracic Surgeons risk calculator. RESULTS Of the 106 patients, 1% underwent quadruple total endoscopic coronary artery bypass, 8% triple, 63% double, and 28% single. The emergent conversion rate for hemodynamic instability was 6.6%. The postoperative renal failure rate (doubling of baseline serum creatinine or dialysis required) was 7.5%. Overall, 23 patients (21.7%) exhibited at least 1 major morbidity/mortality (4 deaths). The number of vessels bypassed (single/double/triple/quadruple) correlated positively with the surgical/operating room time, the lung separation time, vasoactive medication use, blood use, a postoperative ventilation time longer than 24 hours, intensive care unit length of stay, and hospital length of stay. An increased surgical time was significantly associated with major morbidity (P = .011) and mortality (P = .043). A comparison with the Society for Thoracic Surgeons expected outcomes revealed a similar hospital length of stay but an increased incidence of prolonged ventilation (P = .003), renal failure (P < .001), morbidity (P = .045), and mortality (P = .049). CONCLUSIONS Our results suggest that addressing multivessel coronary artery disease using total endoscopic coronary artery bypass offers no obvious clinical benefits and might increase the morbidity and mortality.

Case 6-2010: Noncardiac surgery in patients with a left ventricular assist device.

ENTRICULAR ASSIST DEVICES (VADs) are being implanted with greater frequency in patients with circulatory failure. These devices can be used for short-term support in hopes that the patient’s myocardium will recover, longerterm as a “bridge” to heart transplantation, or even as permanent solutions to end-stage heart failure, so-called “destination therapy.” As a result of expanded usage, these patients increasingly are presenting for noncardiac surgery. 1 Two cases of patients with left ventricular assist devices (LVADs) undergoing noncardiac surgery are presented. The discussion reviews the different types of devices, their pathophysiology, and the unique perioperative considerations when dealing with these challenging cases. CASE PRESENTATIONS* Case 1: Thoracoscopy A 58-year-old woman with an LVAD for idiopathic dilated cardiomyopathy was scheduled for left thoracoscopy for persistent pleural effusion. Past medical history included New York Heart Association class IV congestive heart failure, which had been managed medically for 10 years, with several months of worsening symptoms. She also had a history of migraines, obesity, mild asthma, and insulin-dependent diabetes mellitus. Her past surgical history included automated implantable cardioverter-defibrillator (ICD) placement, total abdominal hysterectomy with bilateral salpingo-oophorectomy, 3 caesarean sections, and tonsillectomy, all without anesthetic complications. Nine days earlier, she had a Heartmate II LVAD (Thoratec Corporation, Pleasanton, CA) implanted as a bridge to transplant. The original surgery included LVAD insertion, patent foramen ovale closure, and a DeVega tricuspid valve annuloplasty, which proceeded without complications. Intraoperative transesophageal echocardiography (TEE) performed immediately after LVAD implantation showed adequate left ventricular (LV) decompression, no valvular abnormalities, and adequate right ventricular (RV) function. Initial pulmonary artery pressure before LVAD placement was 32/15 mmHg, with minimal change after LVAD insertion. Postoperatively, the patient had been doing well except for some difficulty optimizing her international normalized ratio (INR) with warfarin. A left-sided pleural effusion was noted that did not resolve despite chest tube drainage, and the decision was made to perform a thoracoscopy and pleurodesis. Medications at the time of thoracoscopy included metoprolol, insulin glargine, furosemide, esomeprazole, docusate, and nebulized albuterol/ipratropium. Heparin infusion was stopped the morning of the scheduled thoracoscopy. The patient was allergic to amoxicillin/clavulanate, torsemide, and cefdinir. Vital signs immediately before the induction of anesthesia in

Anesthetic management during cardiopulmonary bypass: a systematic review.

Cardiopulmonary bypass (CPB) required for cardiac surgery presents unique challenges to the cardiac anesthesiologist responsible for providing the 3 most basic facets of any anesthetic: amnesia, analgesia, and muscle relaxation. Unique pathophysiologic changes during CPB result in pharmacokinetic alterations that impact the serum and tissue concentrations of IV and volatile anesthetics. Similarly, CPB causes pharmacodynamic alterations that impact anesthetic efficacy. The clinical significance of these alterations represents a “moving target” as practice evolves and the technology of CPB circuitry advances. In addition, perfusionists choose, modify, and maintain the CPB circuitry and membrane oxygenator. Thus, their significance may not be fully appreciated by the anesthesiologist. These issues have a profound impact on the anesthetic state of the patient. The delivery and maintenance of anesthesia during CPB present unique challenges. The perfusionist may be directly responsible for the delivery of anesthetic during CPB, a situation unique to the cardiac suite. In addition, monitors of anesthetic depth—assessment of clinical signs, hemodynamic indicators, the bispectral index monitor, end-tidal anesthetic concentration, or twitch monitoring—are often absent, unreliable, or directly impacted by the unique pathophysiology associated with CPB. The magnitude of these challenges is reflected in the higher incidence of intraoperative awareness during cardiac surgery. Further complicating matters are the lack of specific clinical guidelines and varying international policies regarding medical device specifications that add further layers of complexity and introduce practice variability both within institutions and among nations. We performed a systematic survey of the literature to identify where anesthetic practice during CPB is evidence based (or not), identify gaps in the literature to guide future investigations, and explore the implications of evolving surgical practice, perfusion techniques, and national policies that impact amnesia, analgesia, and muscle relaxation during CPB.

Aprotinin use during cardiac surgery: recent alterations and effects on blood product utilization

OBJECTIVE To investigate a single institutions changing use of aprotinin and subsequent effects on intraoperative blood product utilization (red blood cells/fresh frozen plasma) and postoperative clinical bleeding requiring reoperation. DESIGN Retrospective study. SETTING Single university institution (University of Chicago). MEASUREMENTS Data from 499 adult patients undergoing cardiac surgery requiring cardiopulmonary bypass (CPB) over a two-year period (February 2005 - January 2007) were reviewed. The first 12 months (Feb 2005 - Jan 2006, Group 2005-2006) of data were compared with that from the second 12-month period (Feb 2006 - Jan 2007, Group 2006-2007). Information regarding patient demographics, surgical procedures, aprotinin use (none, half-dose, full-dose), and blood product use during CPB was retrospectively retrieved and analyzed. MAIN RESULTS When Group 2006-2007 data was compared with that from Group 2005-2006, full-dose aprotinin use had significantly decreased (58% to 17%, P < 0.001), non-use of aprotinin significantly increased (18% to 47%, P < 0.001), while fresh frozen plasma (FFP) utilization during CPB significantly increased (24% to 36%, P = 0.004). Red blood cell (RBC) transfusion rates remained stable (67% - 69%) yet rates of RBC and FFP transfusion during CPB significantly increased (23% to 34%, P = 0.003). There was also a trend toward increased unplanned reoperations for excessive clinical bleeding (0 pts in Group 2005-2006, three pts in Group 2006-2007). CONCLUSIONS As the institutions use of high-dose aprotinin has significantly decreased, the number of patients requiring FFP and FFP/RBC combinations during CPB has significantly increased. Furthermore, a trend toward increasing incidence of unplanned reoperations for excessive clinical bleeding was noted.