Skip to Main Content

++

INTRODUCTION

++

Cardiothoracic surgery entails unique, often extreme, conditions in comparison to noncardiac surgery. Profound hemodynamic and physiologic perturbations associated with hypothermic cardiopulmonary bypass (CPB) and circulatory arrest lead to unique dosing considerations for anesthetic drugs, anticoagulants, vasoactives, inotropes, and antifibrinolytics. This chapter will review the pharmacologic considerations of cardiac anesthesia chronologically in stages, from premedication and induction to pre-CPB maintenance, initiation of CPB, separation from CPB, and the post-CPB period. A special discussion will review the unique pharmacologic approach to anticipated deep hypothermic circulatory arrest (DHCA).

++

PREMEDICATION

++

Anxiolysis/Amnesia

++

Benzodiazepine (eg, intravenous [IV] midazolam 0.02–0.04 mg/kg) may be given prior to arterial line and/or central line placement. Cardiac surgery has among the highest incidence of intraoperative awareness of any elective surgery (1%–2%). Benzodiazepine administration has been shown to decrease the risk of awareness.1 Benzodiazepines also have a relatively slow offset time with respect to their hypnotic effects, particularly in elderly patients. Lorazepam (0.02 mg/kg IV) has a half-life of 12 to 14 hours in healthy young patients, with evidence of residual sedation and electroencephalographic (EEG) changes 8 hours after a single dose.2 In comparison, the half-life of midazolam is 2.8 hours, with EEG returning to near baseline by 3 hours.3 In the setting of cardiac surgery with CPB, delayed awakening attributed to the sedative effects of lorazepam may be more than 9 hours.4 Residual postoperative sedation is of potential concern in patients where early extubation is desired (eg, “fast-track” anesthesia). Midazolam in anxiolytic doses administered preoperatively and pre-CPB is not typically associated with delayed awakening. However, caution should be exercised when considering even a single preoperative dose of lorazepam, or a post-CPB dose of any benzodiazepine, if early extubation is desired.

++

Analgesia

++

Beginning slow titration of IV fentanyl 0.5 to 1.0 mcg/kg or sufentanil 0.05 to 0.1 mcg/kg during placement of invasive lines may be considered.

++

INDUCTION

++

Analgesics

++

Similar blunting of the autonomic response to intubation and sternotomy has been demonstrated for fentanyl, sufentanil, alfentanil, and morphine at equianalgesic doses. Ideally, laryngoscopy should be performed adequate analgesia is in place to avoid or blunt an adverse hemodynamic effect. Although all these opioids are similar in pharmacologic action (ie, μ-receptor agonists), they each have quite different pharmacokinetics. One major difference is the time to peak effect. This difference is important to consider when dosing an opioid just prior to laryngoscopy. As is described in Chapter 5, Figure 5–1, the time to peak effect varies for each opioid: alfentanil, less than 2 minutes; fentanyl, 4 minutes; sufentanil, 6 minutes; and morphine, more than 80 minutes.

++

Sedative–Hypnotics

++

Induction drugs include propofol, etomidate, ketamine, high-dose midazolam, and the combination of ketamine and midazolam. Among the choices of induction agents, propofol leads to the greatest decrease in ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.

Ok

About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessAnesthesiology Full Site: One-Year Subscription

Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessAnesthesiology

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.