Critical care anesthesiology E-Book

Claudia Meazzini

• Herausgeber: Claudia Meazzini
• Kategorie: Fachliteratur
• Sprache: Englisch

Veröffentlichungsjahr: 2020

Beschreibung

This book is dedicated to the management of the critically ill patient, in particular, the one affected by infectious diseases. The book, thanks to its structure, can be useful both to health professionals already operating within health facilities, and to those who have to take the anesthesiology exam for the health professions. The book also contains brief reviews on bacteremia, innate immunity, hemostasis, the coagulation cascade, activation of the complement system and the mechanism of the inflammatory response.

Leseprobe

Contents

Contents

Introduction

Sepsis

Definition

Septic shock

Symptomatology

Pathophysiology

Sepsis and Multiple Organ Dysfunction Syndrome

The inflammatory types

The stages of sepsis

The management of circulatory shock

The SOFA score and the MODS

The main pathogenetic mechanisms of MODS

The diagnosis of sepsis

The inflammatory markers

The proteins of the acute phase

The SeptiFast

The 2017 guidelines - The management of septic patient

The initial resuscitation

Screening for sepsis

Diagnosis

Antibiotic therapy

Focus control

Fluid therapy

Mechanical ventilation

Sedation, analgesia or neuromuscular block

Glycemic control

Renal replacement therapies

Bicarbonate therapy

Venous thromboembolism prophylaxis

Nutrition

Posture

Objectives of care

Sepsis

Definition

Sepsis is a syndrome characterized by a marked systemic inflammatory response (SIRS), performed by the body, to counteract the passage of potentially pathogenic microorganisms from the sepsigenic focus to the circulatory stream (remember that, physiologically, the blood is aseptic, i.e. it is free of pathogenic microorganisms). The mortality of the patient with sepsis is about 10%. The presence of bacteria in the blood is not always associated with sepsis, in fact, when the phlogistic component is missing, there is a "simple" bacteremia. Bacteremia is highlighted through a positive blood culture and can usually present as:

transient and asymptomatic. An example of very frequent transient bacteremia occurs when we brush our teeth vigorously, in fact through this normal movement we are able to involuntarily create small lesions in the periodontal tissues, through which bacteria enter the mouth. Once the pathogenic microorganisms have overcome the micro-lesion created, they enter the bloodstream, and are then spontaneously eliminated by the body;intermittent: it is characterized by a periodic release of bacteria into the bloodstream. Examples of intermittent bacteremia are extravascular abscesses or infections of the body cavities;continuous and persistent: this is usually an intravascular infection. Typical examples of continuous and persistent bacteremia are: infective endocarditis, suppurative thrombophlebitis or aneurysms.

When bacteremia is no longer localized but spreads throughout the body, it determines systemic (for example sepsis or septic shock) and very serious metastatic consequences (for example endocarditis in patients with valvulopathies).

Septic shock

Septic shock is a subset of sepsis, characterized by circulatory and metabolic alterations so severe as to significantly increase the patient's risk of mortality (mortality is greater than 40%). Typical alterations that occur in the patient with septic shock, despite adequate intravenous fluid therapy, are persistent hypotension which requires the use of vasopressor drugs to obtain a MAP greater than or equal to 65 mmHg and a quantity of serum lactate greater than 2 mmol/L or 18 mg/dL.

When there is a suspicion of infection, the QSOFA must be performed; if the QSOFA has obtained a value greater than or equal to 2, the evidence of organ dysfunction must be evaluated, in addition, the SOFA score must be performed. If the SOFA score is also greater than or equal to 2, there is a diagnosis of sepsis. If vasopressor therapy is required to maintain MAP above 65 mmHg despite adequate fluid therapy, lactates should be evaluated. If lactates are less than 2 mmol/L, sepsis is confirmed otherwise the diagnosis is septic shock.

If the patient with a suspected infection is found to have a QSOFA of less than 2, the suspected sepsis should be re-evaluated, otherwise the medical condition monitored and re-evaluated for possible sepsis if clinically indicated, whereas if it is still suspected it is necessary to evaluate if there is evidence of organ dysfunction. If the SOFA is less than 2 and sepsis is clinically indicated, the patient's medical condition is periodically monitored and reassess.

Supplementary worksheet n.1: bacteremia

Bacteremia is the presence of live bacteria capable of reproducing within the bloodstream. It is detected through the execution of a blood culture and is mainly manifested when certain predisposing conditions are present: tissue infections, presence of catheters or devices (venous, arterial, urinary, intracardiac, ostomy, etc.) in the person's body, during the postoperative of some surgical interventions, in the course of assistance procedures or wound care. The presence of a specific microorganism is associated generally with an infection of a certain part of the body, furthermore the type of pathogen determines the occurrence of more or less serious complications. The way in which the pathogenic microorganism reaches the bloodstream determines the distinction between two types of bacteremia: primary or secondary. In primary bacteremia, the pathogens were introduced directly into the blood, while in the secondary they entered the lymph and then into the bloodstream through a lesion present on another body site. The residual time of the bacteria in the blood determines the distinction between three types of bacteremia:

transient: the bacteria stay in the blood for a few minutes or hours;persistent: continuous presence of bacteria in the blood;intermittent: bacteria are released, at intervals of time, from the site of infection into the bloodstream.

Generally this type of condition is asymptomatic and if the patient experiences a typical symptomatology of the inflammatory response, with increase body temperature (fever), chills, increased breathing rate (tachypnea), decrease in blood pressure (hypotension) and gastrointestinal symptoms (abdominal pain, nausea, vomiting or diarrhea), we no longer speak of bacteremia but of sepsis. Two blood cultures are taken from two different body sites for diagnosing bacteremia. Blood cultures performed at regular intervals can detect the presence of persistent bacteremia. Treatment involves the timely use of empirical antibiotics, to be replaced later with specific antibiotics when the bacterium responsible for bacteremia is recognized through the results obtained with blood culture.

Empirical antibiotics are chosen based on the most likely source of infection, on the patient's medical history, on the severity of symptoms and allergic drug reactions.

Symptomatology

The interaction between the host organism and the toxic products of the causative agent (bacteria/viruses/fungi) determines the manifestation of clinical symptoms. Symptoms of sepsis are generally specific and contain the following alterations:

fever (T°>38°C) with shaking chills or hypothermia (T°<36°C);tachycardia (heart rate greater than 100 beats per minute);altered mental status (mental confusion, lethargy, etc.);significant amount of associated edema;hypovolemia and hypoxemia;hypotension (the systolic arterial pressure is lower than 100 mmHg). The patient with sepsis has marked hypotension caused by generalized vasodilation induced by: excessive production of vasodilatory chemicals, such as nitric oxide radicals;deficiency of vasoconstrictive chemicals, such as vasopressin (Antidiuretic Hormone, ADH);