Anesthesia in Severe Sepsis - Diagnostic Criteria and Management

Introduction:

Sepsis, a syndrome characterized by systemic inflammation and acute organ dysfunction in response to infection, is a significant healthcare issue that affects people of all ages worldwide. Anesthetists play a critical role in the multidisciplinary management of patients with severe sepsis, beginning with their initial worsening at the unit and continuing through the shift to the diagnostic imaging suite and intraoperative treatment for emergency surgery. Severe sepsis affects one to two percent of all hospitalizations and can account for up to 25 percent of intensive care unit (ICU) bed occupancy. It occurs commonly in older people, immunocompromised patients, and critically ill patients, and it is a leading cause of death in ICUs worldwide. In non-cardiac ICU patients, sepsis is the second leading cause of death. Despite improvements in medical services over the last ten to 15 years, mortality remains high at 30 to 50 percent.

What Are the Etiology of Sepsis?

• Both infectious and non-infectious agents can cause severe sepsis. However, infections are prevalent and treatable. Therefore, an infective reason should be pursued in patients presenting with clinical signs of systemic inflammation (SIRS).

• Community-acquired infections are easier to identify in previously healthy patients than nosocomial infections in debilitated hospitalized patients. Conditions that cause sepsis comprise central nervous system (CNS) infections.

• Although bacterial infections are the most prevalent infectious cause of septic shock, viruses and fungi can also induce it. Acute systemic diseases, such as myocardial infarction, pulmonary embolism, and acute pancreatitis, are non-infectious causes.

What Is the Mode of Anaesthetic Management of a Patient with Sepsis?

• Anesthetists are commonly associated with the care of critically ill patients in the emergency unit, operating room, or intensive care unit. Infection control, which includes surgical drainage of an abscess or surgical excision of necrotic tissue, as well as early efficient antimicrobial therapy, is necessary for the successful treatment of a patient with severe sepsis.

• Early hemodynamic optimization before the advancement of organ failure lowered the mortality rate by 23 percent in high-risk surgical or trauma patients with sepsis compared to those optimized after the progression of organ failure.

What Is the Preoperative Assessment of a Patient with Sepsis?

• Although not every patient with severe sepsis has an infective focus, it is advisable to thoroughly examine patients in search of a source of infection.

• The initial source may be obvious (for example, trauma, burns, or recent surgery) or more challenging to identify (for example, empyema, gallbladder disease, pancreatitis, gynecological sepsis, soft tissue, and bony infections), especially in agitated and uncooperative individuals.

• The examination should concentrate on the level of intravascular hydration, the severity of SIRS, shock, or multi-organ dysfunction, and the sufficiency of hemodynamic resuscitation.

What Are the Diagnostic Criteria for Sepsis?

Some of the following clinical signs or laboratory data that help in diagnosing are:

1. Infection: Either confirmed and documented or suspected case of infection.

2. Systemic Inflammation Signs Include:

A. Parameters in General:

1. Fever - core temperature greater than 38.8 degrees Celsius.

2. Hypothermia - low body temperature (core temperature less than 36.8 degrees Celsius).

3. Tachycardia- Heart beats more than 90 beats per min.

4. Tachypnoea - Breathing rate of more than 30 beats per min.Changes in the mental status of the patient.

5. Increased Fluid - Significantly increased fluid balance by more than 20 ml/kg (milliliters per kilogram) body weight over 24 hours.

6. Hyperglycemia - increased blood glucose levels to more than 7.7 mmol (millimoles) per liter in the case of non-diabetic patients.

B. Parameters of Inflammation:

1. White blood cell count (WBC) less than four or greater than twelve, or greater than ten percent of the total immature forms,

2. C-reactive protein and plasma procalcitonin greater than two or above the normal values.

C. Parameters of Hemodynamics:

1. Hypotension in the arteries (systolic arterial pressure (SAP) less than 90 mm Hg).

2. Venous oxygen saturation (SvO2) greater than 70 percent.

3. Cardiac index (CI) greater than 3.5.

D.Parameters of Organ Dysfunction:

1. Hypoxic- PaO2 (the partial pressure of oxygen in the arterial blood) or FIO2 (fraction of inspired oxygen) less than forty.

2. Creatinine levels rise above 0.5 mg per dl (milligrams per deciliter).

3. Coagulopathy- INR (international normalized ratio) greater than 1.5, and bowel sounds missing.

4. Hyperbilirubinemia.

E. Parameters of Tissue Hypoperfusion:

1. Lactate greater than three mmol per liter.

2. Reduced capillary refill.

3. Skin mottling.

What Is the Intraoperative Management of a Patient with Sepsis?

During the intraoperative period, the main objective of the anesthetist is to deliver safe and optimal care for critically ill septic patients so that they can benefit as much as possible from the surgical or radiological source control procedure. The major part of surgical source control procedures is best performed under general anesthesia in the operating room.

1. Before Induction:

• It is critical to be aware of the microbiological samples sent out for culture, the antimicrobial agents that have been administered, and the timing of the next scheduled dose to optimize the type and timing of intraoperative antimicrobial therapy.

• As the process may induce further bacteremia and clinical deterioration, therapeutic dosages of effective antibacterial drugs should be retained throughout the perioperative period. Therefore, invasive hemodynamic monitoring, in addition to standard intraoperative monitoring, is probable to be indicated.

• Serial measurements of arterial blood gases and lactate concentrations from near-patient testing equipment should be easily accessible. In addition, an adequate volume resuscitation intravascular device should be considered if significant volume loss is expected during the surgical procedure.

2. Induction of Anesthesia and Initiation of Mechanical Ventilation:

• Because of the cumulative effects of sepsis, anesthesia, intravascular volume loss, bleeding, and surgical stress, patients who undergo source control procedures are entirely in an unstable cardiovascular state.

• Before inducing anesthesia, the lungs may be de-nitrogenated by breathing 100 percent oxygen through a closely fitted facemask for up to three minutes. Because many surgical techniques on severely septic patients are performed urgently, a modified rapid sequence induction, possibly using Rocuronium instead of Succinylcholine to assist tracheal intubation, may be necessary.

• Most intravenous or inhalation anesthetics produce vasodilation or decreased ventricular contractility. Therefore, anesthesia induction should ideally be an intentional step-by-step process involving small doses of intravenous anesthetic agents titrated to clinical response.

• The induction agent or narcotic used is less important than the care with which it is injected. Ketamine or Midazolam may provide some hemodynamic stability, and short-acting opioids such as Fentanyl or Alfentanil may allow the dose of the anesthetic induction agent to be reduced.

• Apart from Remifentanil, impaired hepatic and renal perfusion may enhance the effects and duration of action of intravenous opioids. In anesthesia induction for septic and unstable patients, Remifentanil infusion, either as a primary choice of drug or as a background effective alternative to another induction drug.

• Even though it causes bradycardia, many of these patients are tachycardic, and it has little effect on myocardial contractility. Furthermore, Remifentanil prevents abrupt decreases in systemic vascular resistance.

• To counterbalance the hypotensive effect of anesthetic agents and positive pressure mechanical ventilation, continued volume resuscitation and incremental doses of vasopressors are beneficial. Vasopressors that can be used include Ephedrine, Phenylephrine, and Metaraminol.

• The objective of mechanically ventilating patients with severe sepsis is to maintain adequate oxygenation by using sufficiently high fractional-inspired oxygen levels.

3. Maintenance of Anesthesia:

• No data indicate that maintaining anesthesia through inhalation or intravenous administration improves outcomes. Inhalation, intravenous, and opioids, such as Remifentanil, are possible for maintaining anesthesia.

• The anesthetist should select the technique that better suits their evaluation of the individual patient's risk factors and comorbidities, as well as their expertise and experience.

• In patients suffering from significant lung dysfunction, maintaining stable concentrations of anesthetic agents in the brain may be more accurately accomplished using intravenous rather than inhalation agents. Regardless of the technique used, bispectral index monitoring can estimate the depth of anesthesia achieved.

• During surgery, if loss of blood or release of bacteria from the systemic circulation or endotoxins may complicate the hemodynamic state, blood products should be transfused immediately.

• Intravascular volume resuscitation should be continued as directed during the surgical procedure. Changes in dynamic markers of volume responsiveness can be utilized intraoperatively to guide intravenous volume therapy, particularly in patients with sinus rhythm and lungs ventilated by controlled mechanical ventilation.

• To establish changes in stroke volume variation, concurrent transoesophageal echocardiography or oesophageal doppler could be employed.

• Numerous devices are available to monitor cardiac output changes (pulmonary artery catheter) at specific intervals (transesophageal echocardiography).

• Cardiovascular variables (heart rate, cardiac filling pressures, inotropic state, systemic arterial pressure) can be altered during the surgical procedure to optimize tissue oxygen delivery rather than achieve set cardiac output or arterial pressure values.

• Non-cardiogenic pulmonary edema, due to increased capillary permeability in sepsis, may hinder oxygenation. Hypercarbia should be prevented in patients with high intracranial pressure, compensated metabolic acidosis, or during the late stages of pregnancy.

4. Role of Regional Anaesthesia and Nerve Blocks in Anaesthesia for Septic Patients:

• A peripheral nerve block may be beneficial in reducing the sympathetic response to a painful stimulus while preventing the systemic effects of opioids.

• The presence of coagulopathy, the spread of infection locally or systemically, and the fact that local anesthetics may not work effectively in the presence of disease or acidosis may confine the use of regional techniques in septic patients.

• Neuraxial block (spinal and epidural anesthesia) should be administered with caution because the hemodynamic effects of these techniques may be challenging to reverse in the setting of sepsis-induced cardiovascular compromise. Recent blood tests that confirm normal coagulation are required.

5. End of Surgical Procedure:

• Following the surgical procedure, additional neuromuscular blocking agents may be administered to enable surgical closure of the abdomen or thorax. Before leaving the operating room, blood loss should be as low as possible.

• Antimicrobial agent supplementation may be taken into account. Analgesia, sedation, and mechanical ventilation are retained after surgery in patients who require additional surgery and all severely ill patients.

What Is the Postoperative Management of Patients with Severe Sepsis?

• It is vital that antimicrobial therapy, initiated before the procedure, be continued in the intensive care unit and that the time for the next scheduled dose is mentioned. Antimicrobial regimens can be reevaluated daily with the help of microbiological results and modified to ensure efficacy, inhibit resistance, and prevent toxicity. The duration of therapy should be confined to seven to ten days.

• Maintaining adequate glycemic control (less than 8.5 mmol per liter) is critical in managing the septic process.

• Nutrition is a critical component of management in critically ill septic patients. Enteral nutrition through a nasogastric tube is the best alternative for preserving enterocyte integrity and nourishing the patient.

• Antiemetic drugs and gastrointestinal protective measures (stress ulcer prevention) are also recommended. Total parenteral nutrition (TPN) should be considered if enteral nutrition is contraindicated surgically or if enteral nutrition alone is insufficient to meet nutritional needs. Patients may become hypoglycemic if TPN or enteral nutrition is stopped during the perioperative period.

Conclusion:

Sepsis is still a complex area to treat and is associated with a significant mortality rate. Current clinical guidelines can aid in implementing effective management techniques to enhance the outcomes of sepsis patients. Early identification and control of infectious sources and the maintenance of hemodynamic measures during surgical procedures are critical to improving outcomes from an anesthetist and surgical perspective. Intraoperative management would also be appropriate based on a better understanding of the pathophysiology.