Anaesthetic induction agents in patients with severe sepsis or septic shock

Abstract

Sepsis is a complex syndrome that is difficult to define, diagnose and treat; it is a range of clinical conditions caused by body systemic response to an infection, which if it develops in to severe sepsis, is accompanied by single or multiple organ dysfunction or failure leading to death. Sepsis andseptic shock are severe conditions that, when together, may cause multiple organ failure. The anaesthesiologist must be able to take a careful history and physical, as well as be aware that additional tests are necessary to assess the patient status, as preoperative systemic blood pressure is not indicative of adequate volume status. In preparation for surgery, one must anticipate dysfunction and have adequate blood products and antibiotic at hand. The time taken to improve a patient condition before surgery must be balanced against the urgency to surgically treat the underlying problems. Recent studies have shown the outcome from surgery in these high risk patients is improved if the patient condition is optimized preoperatively. When surgery can be delayed (even for a few hours), attempts should be made to resuscitate the patient to insure adequate oxygen delivery, cardiac output, and blood pressure. This is easiest done in theatre, recovery, or ICU. In a few patients immediate surgery is lifesaving and should be carried out as soon as practical. In these patients preparation time is limited, but initial resuscitation (airway, breathing, and circulation) should be completed during anesthesia. Goals of early resuscitation in patients with sepsis include restoration of tissue perfusion and normalization of cellular metabolism. When appropriate fluid administration fails to restore adequate tissue perfusion and arterial pressure, vasopressors are usually necessary to increase mean systemic pressure, cardiac output, and oxygen delivery. The primary goal of the anaesthesiologist during the intraoperative period is to provide safe and optimal care for critically ill septic patients so that they may benefit maximally from the surgical or radiological source control procedure. The majority of surgical source control procedures are optimally carried out in the operating theatre under general anaesthesia. Endotracheal intubation of the critically ill septic patient is one of the most significant challenges an emergency medicine or critical care practitioner will face. The intubation procedure itself is associated with profound physiologic changes. Performing this procedure on a patient with underlying hemodynamic, respiratory, and additional organ compromise can be arduous. Agents to rapidly and safely accomplish this procedure need to be chosen. The caregiver needs to be aware of induction agent side effects, mechanism of action, metabolism, and duration of action. This knowledge is as important as the actual procedural skill. Intubation under adverse circumstances can be worsened with poor choice in induction mediator. In review of induction medications, rapid onset with short duration of action, preservation of hemodynamic parameters, and low adverse side effect profile are key components for successfor severe sepsis and septic shock, two particular candidates rise to the occasion. Ketamine and etomidate appear to be the best current induction options.