Cardiac Stress Response: The Use of Anesthetic Technique to Promote Positive Outcome; Analyzing the Pros and Cons of Technique Cardiac surgery by nature elicits a powerful stress response resulting from activation of stress hormones including epinephrine, norpinephine and cortisol hormones among others. Surgical trauma and blood loss may contribute to this stress response. Some surgeons have suggested that cardio pulmonary bypass surgery in and of itself activates an inflammatory response that results in a stress reaction.

The role of the anesthesiologist in cardiac surgery is to as much extent as possible, to reduce the stress response that results form cardiac surgery. Stress response can be mitigated by a variety of anesthetic technique, including use of opioids and epidural anesthesia. These ideas are explored in greater detail below.

Cardiac Stress Response: The Use of Anesthetic Technique to Promote Positive Outcome; Analyzing the Pros and Cons of Technique

INTRODUCTION stress response may be "semantically complex in nature," as is commonly associated with the process of administering cardiac anesthesia (Cook, 1996). Time pressures and considerations, consequences and technically complicated domains are all involved in the cardiac anesthesia process (Cook, 1996; Rochlin, La Porte & Roberts, 1987). The need to supplement and augment anesthetist practitioner performance has surfaced in recent years, in part due to the advent of increased technology which includes the development of computerized systems that are capable of managing data flow during cardiac operations (Cook, 1996; Wiener, 1985).

An anesthetists ability related to cardiac surgery is contingent upon his/her ability to integrate multiple, discrete and "loosely connected devices" available through modern technology (Cook, 1996). These devices purport to decrease the stress response by delivering an appropriate amount of anesthetic drug or device in the correct amount at the right time, thus reducing the overall likelihood for stress during surgery.

The purpose of this paper is to discuss and analyze the significance of anesthetic technique as associated with the outcome of patients enduring cardiovascular surgery. It is expected that research will indicate that an increased stress response results from the prospect and endurance of cardiac procedures; this increased stress response is commonly associated with an increased likelihood for negative post operative outcome; therefore the purpose of this study is to improve the importance of improving patient stress and pain responsive through anesthetic technique in order to improve the poster operative outcome of cardiac patients.

SYNOPSIS

Anesthesia as related to cardiovascular surgery typically entails procedures that are undertaken to correct structural abnormalities and defects of the heart and related blood vessels; most commonly affected are the coronary artery (Cook, 1996). Common cardiac procedures that elicit a stress response, and require anesthesia intervention include coronary bypass surgery, aortic valve replacement and mitral valve replacement among other procedures (Cook, 1996).

Typically the course of procedure required to correct defects of the heart or acute injury requires manipulation of the organ itself (Cook, 1996). The heart must often be stopped, and artificial oxygenation and blood circulation are often taken over via a "mechanical cardiopulmonary bypass or CPB system (Cook, 1996). Use of a mechanical system to control the functioning of the heart require the connection of tubes to the larger arteries that lead blood into and out of the heart. The heart is then typically restarted, and the process of pumping and oxygenating blood reinitiated and returned to the patient (Cook, 1996).

Anesthesia intervention is a requirement of any cardiac bypass or related surgery. Any intervention within the heart requiring anesthesia will ultimately result in a stress response upon the heart. Anesthesia practitioners are generally responsible for maintaining the overall "hemodynamic stability" of patients, which can be measured by blood pressure and heart rate among other variables (Cook, 1996).

The production of an anesthetic state is imposed to prevent awareness and movement, as well as minimize harmful effects which are often associated with the physiological stress produced by cardiac surgery in and of itself (Cook, 1996). By putting patients into an anesthetic state, surgeons can perform corrections to a diseased heart while maintaining hemodynamic status. It is critical for anesthesiologists to maintain an appropriate balance between blood pressure, heart rate and cardiac output in order to reduce the likelihood or organ damage to patients (Cook, 1996).

There are certain systems within the body that are more susceptible to cardiac stress responses while under anesthesia than others; these include the brain, heart and kidneys (Cook, 1996). The induction of an "anesthetic state" typically requires that narcotics, muscle relaxants and other "amnesic" agents be injected into the patient so that they have no cognitive or technically physiologic response to the surgery being...

Cardiac patients in particular are far more susceptible to "rapid and profound hemodynamic changes" and stress responses that can be in fact, life threatening (Cook, 1996). These changes are often unpredictable in nature (Cook, 1996).
Stages of Anesthesia for Cardiac Patients

There are several stages of the anesthetic response that patients endure throughout the course of surgery. These include the preanesthesia phase, which typically lasts between 30 and 60 minutes, where the practitioner prepares the patient utilizing several "intravenous catheters" meant to deliver fluid and blood throughout the patient during the course of surgery (Cook, 1996). Anesthetic practitioners also prepare cardiac patients with an arterial blood sampling line, referred to as the a-line, and a pulmonary artery catheter or PAC (Cook, 1996). This allows data to be displayed to physicians and anesthetists during the actual cardiac procedure. Typically an endotracheal tube is also inserted into the patient, referred to as intubation, which may further elicit an additional cardiac stress response (Cook, 1996).

Drugs are the commonly administered which elicit an anesthetic state of amnesia. The anesthesia practitioner may administer heparin during a coronary bypass procedure to produce a state of anticoagulation (Cook, 1996). Potentially "injurious hemodynamic change" is very possible at this phase, where the surgeon commences manipulation of the heart and surrounding vessels in order to "repair" the organ (Cook, 1996).

Coordinated activity between the anesthesiologist and surgeon must come during what is referred to as the "coming off pump phase" where the load of pumping is transferred from "the CPB machine to the patient's heart" (Cook, 1996). At this point often blood transfusions occur as well as the infusion of several drugs that force the heart into contracting forcefully and acting on its own to produce adequate cardiac output (Cook, 1996).

The job of an anesthesiologist during a CBS procedure includes minimizing the autoimmune and stress response. Studies have shown that "greater fear or distress prior to surgery" is typically associated with slower and more complex and complicated post-operative recovery (Glaser, et. al, 1998). Stress response in fact delays healings. The body naturally perceives surgery as a "threatening" experience, and thus a variety of stress factors are involved in the surgical process (Glaser, et. al, 1998). Among these stress concerns include worries related to survival and recovery, as well as separation from family (Glaser, et. al, 1998); these factors are especially prevalent among cardiovascular patients, who face at bets long postoperative periods and "delicate" recovery prognosis.

Research has revealed that a correlation exists between stress and two outcome variables: healing time and IL (interleukin 1) production (Glaser, 1998). Painful stress experiences are typically associated with tissue damage; stress induced during cardiovascular bypass surgery has also been shown in animals to possibly elicit the suppression of natural killer cell activity, or NKCA, "lymphocyte proliferative responses to mitogens" and antibody production (Liebeskind, 1991; in Glaser, 1998). Plasma levels of chemical components including epinephrine, cortisol and beta-endorphin are subsequently elevated went the sympathetic nervous system is activated as occurs during times of CBS (Liebeskine, 1991; from Glaer, 1998).

Cardiac stress elicits a neuroendocrine and immune response. Thus anesthesiologists must pay careful attention to how they manage and reduce the overall stress response in cardiac patients. Studies have shown that immune suppression during surgery occurs when natural killer cell activity is stimulated, a result of painful stressors that occur during the natural surgical process (Salomaki, et. al 1994 & Glaser, 1998).

A connection between SNS, HPA axis and the immune system has been identified in cases where surgery induced stress changes have been identified, particularly in the case of cardiac patients (Koltun, et. al, 1996; from Glaser, 1998).

Even operations which physicians would normally consider "minor" may "provoke strong emotional reactions in patients" (Johnston, 1988; from Glaser, et. al, 1998). Stress has also been shown to delay "wound repair" (KiecoltGlaser, Marucha, Malarkey, Mercado, & Glaser, 1995). Pain also elicits an immune and endocrine response (Liebeskind, 1991; Glaser, 1998). As psychological components obviously, therefore can be attributed to the stress response and subsequent wound healing, short-term recovery is contingent in part upon the ability of the anesthetist to reduce the overall stress response in cardiac bypass and similarly afflicted patients.

Several studies have indicated that anesthetic techniques "that block transmission of non-receptive impulses either locally" (Pasqualucci, et. al, 1994) or at the "level of the spinal cord" (Koltun, et. al,…