Definition
A.Systemic Inflammatory Response Syndrome (SIRS): Clinical syndrome that is a form of dysregulated inflammation; can be present with or without infection; considered the clinical expression of host response to inflammation resulting from nonspecific insult.
1.SIRS is considered to be present when two or more of the following signs are present:
a.Temperature greater than 38°C (100.4°F) or less than 36°C (96.8°F).
b.Heart rate more than 90 beats per minute.
c.Respiratory rate greater than 20 breaths per minute or arterial carbon dioxide (PaCO2) of less than 32 mmHg.
d.Abnormal white blood cell count (>12,000/μL or <4,000/μL or >10% immature forms; i.e., bands).
B.Bacteremia: Traditionally, essentially synonymous with septicemia; today, defined as the presence of viable bacteria in the blood.
1.Signs and symptoms range from asymptomatic, noninfectious to full blown sepsis.
C.Sepsis (general): A continuum of severity ranging from infection and/or SIRS, to sepsis, severe sepsis, and septic shock.
D.Sepsis: Traditionally, clinical syndrome with a collection of signs (objective) and symptoms (subjective); patient meets SIRS criteria and has a source of infection (this definition has been changed). Severe sepsis: Usually defined as sepsis with persistently low blood pressure, despite fluid resuscitation.
1.According to the Surviving Sepsis 2016 Campaign, sepsis is a life-threatening dysfunction caused by a dysregulated host response to infection (and category of severe sepsis has been removed).
2.Organ dysfunction is defined by an increase over baseline in the sequential organ failure assessment (SOFA) score (see Table 10.3). In critically ill patients, SOFA has a higher predictive value of in-hospital mortality than the SIRS criteria. Patients who meet SOFA criteria have greater than 10% predicted mortality.
a.SOFA score.
i.Mortality prediction score based on evaluation of organ dysfunction.
ii.Based on six different criteria: Respiratory, cardiovascular, hepatic, coagulation, renal, and neurological.
iii.Calculated on day of admission to the ICU and daily thereafter, until discharged from the ICU.
iv.Recommended that one uses the worst value to calculate the patient’s daily score.
b.Quick SOFA score (qSOFA).
i.System used as a prompt to recognize patients with infections who are likely to be septic, yet not in the ICU.
ii.Developed with the intention to be used in the prehospital, ED, non-ICU floors in a hospital.
iii.Bedside scoring system that assesses three components.
1)1 point: Systolic blood pressure less than or equal to 100 mmHg,
2)1 point: Respiratory rate greater than or equal to 22 breaths per minute.
3)Altered mental status: Glasgow Coma Score of less than 15.
iv.Per the Surviving Sepsis Guidelines: A patient with an infection and a qSOFA score of 2 or more has a higher risk of death or prolonged ICU stay.
E.Septic shock: Sepsis, a vasodilatory or distributive shock, defined by the 2016 Surviving Sepsis Campaign as including the criteria for sepsis, and even with adequate fluid resuscitation meets the following conditions:
1.Unresponsive to fluid resuscitation.
2.Serum lactate levels more than 2 mmol/L.
3.Need for vasopressors to maintain mean arterial pressure (MAP) of 65 mmHg or more.
Incidence
A.SIRS.
1.The incidence of SIRS increases as the level of care unit acuity increases.
2.Progression of SIRS was noted to be: 26% developed sepsis, 18% developed severe sepsis, and 4% developed septic shock within 28 days of admission.
B.Bacteremia.
1.Often asymptomatic, transient, and without consequences.
2.25% to 45% with significant bacterial counts develop sepsis.
C.Sepsis.
1.One of the leading causes of death in the United States; between 230,000 and 370,000 people die of sepsis annually in the United States.
2.Sepsis is diagnosed in more than 25% of all hospitalized patients. The incidence of sepsis diagnosis has increased over the past 10 years.
3.Septic shock is associated with higher mortality than sepsis alone (40% vs. 10%).
4.Sepsis develops in 80% of patients prior to being admitted to a hospital.
5.7 out of 10 patients diagnosed with sepsis had recently seen a healthcare worker or had a chronic disease requiring frequent medical care.
Pathogenesis
A.SIRS.
1.An insult/injury occurs, followed by local cytokine production, a local inflammatory response.
a.Inflammatory cascade is an important piece of pathophysiology.
b.Local cytokines are released to the systemic circulation, further provoking local response.
2.This leads to growth factor stimulation, with the recruitment of platelets and macrophages.
3.The acute phase of the response is controlled by a decrease in proinflammatory mediators and release of endogenous antagonists. If homeostasis is not restored with cytokine release into the systemic circulation, significant reaction occurs.
4.Continued exposure to injury/illness results in continuation of this inflammatory cascade, leading to progressive illness.
B.Bacteremia.
1.Sources of gram-negative bacteremia: Gastrointestinal (GI) tract, genitourinary tract, or from the skin on patients with decubitus ulcers.
2.Staphylococcal bacteremia: Common in patients with intravenous (IV) catheters and IV drug abusers.
3.Infection above the diaphragm causing bacteremia: Most likely gram-positive organism.
4.Infection below the diaphragm causing bacteremia: Most likely gram-negative bacillus.
C.Sepsis.
1.Sources of infections most likely associated with sepsis: Infections of the respiratory tract, gastrointestinal tract, genitourinary tract, and the skin. If the nervous system becomes involved, the mortality is greatest.
2.Bacterial infections: Most common cause of sepsis.
a.Common causal bacteria: Staphylococcus aureus, group A Streptococcus, Escherichia coli, Klebsiella species, Enterobacter species, and Pseudomonas aeruginosa.
b.Fungal and viral sources: Also possible causes.
3.Immunocompromised patients: Susceptible to fungal bloodstream infections from Candida species.
4.Culture Negative Severe Sepsis (CNSS).
a.Sepsis without a documented microbiological source.
b.Affects 28% to 49% of hospitalized patients with sepsis.
5.Sepsis: A complex interaction between a host’s response to an invading pathogen and the pathogen itself.
a.Most of the time, the response to an invading pathogen is a normal reaction in order to maintain overall integrity of the host. The normal host response may include fever and leukocytosis.
b.Any pathogen that violates at the tissue level is potentially able to evade the host’s humeral and cellular immune system leading to widespread, systemic infection.
c.Although the early phases of sepsis are pro-inflammatory in nature, if not controlled, these may progress to a significant immunosuppressed phase where the host is at an increased risk for secondary infections, along with reactivation of latent viruses.
i.Initially, pro-inflammatory molecules enter the bloodstream in an effort to ward off the pathogen.
ii.With sepsis, an overactive immune response to an infection causes the natural checks and balances to fail. Rather than dissipating, the activated inflammatory forces spread beyond the infected area.
iii.As these pro-inflammatory molecules travel they cause dilation and endothelial damage, leading to leakage of fluid out of the intravascular system and interstitial edema accumulation.
iv.This vascular leakage causes disruption of oxygen, nutrients, waste products, and fluids through the capillary walls.
v.If left unchecked, eventually organs become hypoxic and begin to fail.
d.A patient’s response to sepsis is highly dependent on a variety of both host variables (i.e., age, comorbidities, genetics) and pathogen factors (i.e., virulence, susceptibility to treatment).
Predisposing Factors
A.SIRS.
1.Infection.
2.Autoimmune disorders.
3.Pancreatitis.
4.Vasculitis.
5.Thromboembolism.
6.Burns.
7.Surgery.
B.Bacteremia.
1.IV drug user.
2.Presence of indwelling catheter (i.e., urinary catheter, IV catheter).
3.Presence of multiple abscesses.
4.History of structural heart disease and/or prosthetic heart valve.
5.History of recent dental procedure.
6.History of recent surgical treatment of an abscess or infected wound.
C.Sepsis.
1.Younger than 1 year or over 65 years of age.
2.Weakened immune system.
3.Comorbid diseases.
4.Unrecognized, untreated, or undertreated infection.
5.Any condition listed under bacteremia.
Subjective Data
A.Common complaints/symptoms.
1.Condition specific.
a.SIRS.
i.Temperature greater than 100.4°F.
ii.Heart rate greater than 90.
iii.Respiratory rate greater than 20.
iv.Abnormal WBC count (>12,000 or <400,000).
b.Bacteremia.
i.Possibly asymptomatic or only a mild fever.