Sepsis and ARDS Flashcards
Sepsis
Epidemiology
- High mortality rate ⇒ 2-25x risk of dying
- Mortality 20-60% depending on severity
- Costs ~ 50k per episode of sepsis
Infection
Definition
Invasional of normally sterile tissues by microorganisms.
Inflammatory response to the presence of microorganisms.
Bacteremia
The presence of viable bacteria in the blood.
Sepsis
Definition
Life-threatening organ dysfunction caused by a dysregulated host response to infection.
Septic Shock
Definition
A subset of sepsis with circulatory and cellular/metabolic dysfunction associated with a higher risk of mortality.
Sepsis
Pathophysiology
Normal immune processes in response to infection results in host injury via tissue injury caused by hypoperfusion and immune dysregulation.
- Invasion of infectious pathogen with evasion of immune defenses ⇒ invasive infection
- Immune cells signaling via inflammatory cytokines, complement, and coagulation components
- With uncontrolled infectious process, localized inflammation becomes uncontrolled
- Endothelial membranes throughout the body becomes activated
- Neutrophils and platelets adhere to activated surfaces
- Released reactive oxygen radicals cause additional endothelial damage
- NO released ⇒ vasodilation of capillary beds ⇒ ↑ permeability
- Intravascular fluid leaks into interstitial space
- Systemic hypotension develops
- Can lead to organ dysfunction and death
Sepsis
Diagnostic Criteria
Two-step evaluation:
-
Possible sepsis
The presence of infection plus at least 2 of the following:- SBP ≤ 100 mmHg
- RR ≥ 22/min
- AMS
If ≥ 2 present, go to next step to look for organ dysfunction.
-
Sepsis
Exists if ≥ 2 of the following markers of organ dysfunction are present:- Respiratory ⇒ hypoxia
- Coagulation ⇒ thrombocytopenia
- Liver ⇒ ↑ bilirubin
- Cardiovascular ⇒ ↓ MAP ± vasopressor requirement
- CNS ⇒ ↓ me
- Renal ⇒ ↑ serum creatinine or ↓ urine output
Septic Shock
Diagnostic Criteria
Hypotension (MAP < 65 mmHg) requiring vasopressors despite adequate fluid resusitation
AND
Elevated serum lactate > 2.0 mmol/L
Systemic Inflammatory Response Syndrome (SIRS)
Definition
The body’s response to inflammation from a variety of insults.
(Both infectious and non-infectious)
SIRS
Diagnostic Criteria
Defined as presence of ≥ 2 of the following criteria:
- Temperature > 38°C or < 36°C
- Heart rate > 90 bpm
- RR > 20 rpm or PaCO2 < 32 mmHg
- WBC count > 12,000 cells/mm3 or < 4,000 cells/mm3
SIRS
Non-infectious Etiologies
- Pancreatitis
- Severe trauma
- Thermal burns
- Toxins or environmental exposures
- Anaphylaxis
Sepsis
Clinical History
Presentation can be variable ⇒ need a high index of suspicion.
- Any specific risks for infection
- Recent infection / abx use
- Recent hospitalization, procedures, or invasive devices
- Living situation (community vs nursing home)
- Detailed ROS looking for signs of infection and organ dysfunction
- General ⇒ fever, chills, lethargy
- Specific ⇒ cough, dysuria, frequency, dec. urine output
Sepsis
Physical Exam
A thorough exam guided by history:
-
Vital signs ⇒ temp, HR, RR, BP, pulse ox
- Hypothermia ⇒ a worse prognostic sign
-
Evidence of organ dysfunction
- AMS
- Jaundice / scleral icterus
- Dec. bowel sounds
- Edema
- Petechiae or other signs of coagulopathy
-
Evidence of infection
- Heart murmur
- Pulmonary findings
- Bladder or CVA tenderness
- Skin findings
-
Septic shock is distributive shock
- Extremities may be warm initially
- Eventually vasoconstriction occurs
- Extremities become cold and mottled (cyanotic)
Sepsis
Etiologies
Bacteria are the most common cause of sepsis:
- S. aureus
- Group A Strep
- E. coli
- Klebsiella spp
- Enterobacter spp
- P. aeruginosa
Sepsis
Risk Factors
- Neutropenia
- Asplemia
- Cirrhosis
- Alcohol abuse
- DM
Multidrug-Resistant (MDR) Organsims
Risk Factors
- Prolonged hospitalization / chronic facility stay
- Recent abx use
- Prior hospitalization
- Prior colonization / infection w/ MDR organisms
Sepsis
Initial Evaluation
-
Consider DDx for sepsis
- Infection
- SIRS due to non-infectious causes
- History and physical exam
-
Lab evaluation
- Blood cultures ⇒ at least 2 sets before starting abx
- Unless this will cause > 45 min delay in treatment
- ⊕ cultures ⇒ de-escalation of abx therapy
- Also collect sample from IV catheter if present
-
Culture any site which may be source of infection
- CNS, urine, wound, respiratory secretions
- Pan culture not recommended
- CBC ⇒ look for ∆ in WBC
- CMP ⇒ look for e/o organ dysfunction
- Serum lactate
- DIC panel
- Blood cultures ⇒ at least 2 sets before starting abx
- Imaging as indicated
Sepsis
Management
Medical emergencies ⇒ need early recognition and immediate treatment.
-
Maintain oxygen delivery / perfusion to tissues
-
Maintain BP ⇒ MAP ≥ 65 mmHg
- IV fluid resuscitation
- Vasopressor agents in septic shock
- Monitor for signs of adequte perfusion
-
Maintain BP ⇒ MAP ≥ 65 mmHg
-
Control underlying infection
-
Empiric abx treatment ⇒ within 1 hour
- Consider host factors and local microbiology
-
Source control
- Remove IV devices if source/possible
- Drain abscesses if present
- Debride wounds if present
-
Empiric abx treatment ⇒ within 1 hour
-
Mechanical ventilation
- May be needed to maintain oxygenation
Acute Respiratory Distress Syndrome
Definition
A clinical syndrome of severe dyspnea of rapid onset with hypoxemia and diffuse pulmonary infiltrates leading to respiratory failure.
ARDS
Epidemiology
-
Risk factors:
- Older age
- Chronic ETOH abuse
- Metabolic acidosis
- Severity of underlying critical illness
- Can be caused by diffuse lung injury from multiple medical or surgical issues
- > 80% of cases caused by:
- Sepsis or bacterial PNA ⇒ 40-50%
- Trauma, multiple transfusions, aspiration of gastric contents, drug OD
ARDS
Pathophysiology
- Alveolar capillary endothelial and epithelial cells injured
- Loss of tight alveolar barrier
- Protein rich edema fluid accumulates in interstitial and alveolar spaces
- Hyaline membranes form and pulmonary vascular injury occurs
- Results in severe hypoxemia and hypercapnia
ARDS
Clinical Manifestations
- Dyspnea and sensation of inability to get enough air
- Patient exhibits tachypnea, ↑ WOB, respiratory failure
ARDS
Evaluation
CXR ⇒ alveolar and interstitial opacities involving at least 75% of lungs
∆ non-specific and can look like pulmonary edema
ARDS
Management
Treat underlying cause of ARDS.
Supportive care including ventilator support.
