Acute sepsis Flashcards
Definition of sepsis
life - threatening organ dysfunction; caused by disregulated host response to infection
What’s septic shock?
Septic shock:
subset of sepsis, where there are profound
circulatory, cellular and metabolic abnormalities -> associated with a greater risk of death (as compared
to sepsis on its own)
Why sepsis causes organ damage? (simple pathology)
Pathology:
- infective material in a blood stream -> decreased oxygenation to the tissues - infective material -> immune response from white blood cells (as infective material is in the blood stream) -> release of NO -> vasodilation -> increased vessel diameter -> increased leakiness (spread of the infection to other organs)
* low tissue perfusion is also due to increased leakiness -> more tissue fluid accumulation -> more barrier for oxygen diffusion
- damage to blood vessels due to white blood cells releasing lytic enzymes against infected material (# to blood vessels as a side effect) -> coagulation factors will activate -> disseminated intravascular coagulation
Possible complications of septic shock (only name 4 conditions)
- DIC (disseminated intravascular coagulation)
- ARDS (acute respiratory distress syndrome)
- SIRS (systemic inflammatory response syndrome)
- MODS (multiple organ dysfunction syndrome)
Why ARDS is a possible compication of a septic shock? (pathophysiology)
lungs are highly vascularised -> so during septic shock -> blood vessels are
damaged -> oxygen cannot be absorbed properly into the lungs
What is needed to diagnose SIRS?
SIRS = systemic inflammatory response syndrome
(2 criteria + infection) = SIRS
What’s MODS?
MODS - Multi-Organ Dysfunction Syndrome
- progressive dysfunction of 2 or more organ systems that result from uncontrolled inflammatory response (SIRS)
Features / clinical presentation of a septic shock
- Fever (>38.3 degrees) or hypothermia (<36.0 degrees)
- HR > 90/min (or more than 2 SD above normal value for age)
- Tachyopnea (increased RR) >20 / min
- altered mental status
- significant oedema or positive fluid balance (as decreased urine output)
- warm skin: skin is the largest organ in the body -> blood vessels dilate -> heat is taken up from the vessels
- hyperglycaemia (plasma glucose >140 mg/dL or 7,7mmol/L) in absence of diabetes
Inflammatory blood changes (on the blood test)
- leukocytosis (WBC count >12, 000)
OR
- leukopenia (WBC count < 4, 000)
- normal WBC count but >10% of immature forms
- increased C reactive protein
- increased plasma procalcitonin (PTC)
*PCT - it is a peptide precursor of calcitonin; it is involved with
calcium homeostasis
*Normal level of PCT is below detection (0.01 ug/L); PCT rises in response to pro-inflammatory stimulus (e.g. bacteria) -> it is therefore acute phase reactant
How to calculate MAP
MAP = [(2x diastolic) + systolic]/ 3
*diastole counts twice of the systole because 2/3 pf cardiac cycle is spent in diastole
What’s normal MAP?
Normal MAP: 70 - 110
*we need MAP of at least 60 to perfuse arteries, brain and kidneys
Possible hemodynamic abnormalities in inflammation (that leads to shock)
- hypotension: BP <90 mm Hg
- MAP <70 mm Hg
OR: severe decrease >40 mmHg in adults
How to recognize organ dysfunction?
Possible abnormalities
- arterial hypoxemia (PaO2/FiO2 is <300)
- acute oliguria (urine output <0.5 mL/kg/hr for at least 2 hr despite adequate fluid resuscitation)
- creatine increase (>0.5 mg/dL or 44.2 umol/L)
- ileus (absent bowel sounds)
- coagulation abnormalities (INR >1.5 or aPTT > 60 s)
- raised D-Dimer (as thrombocytopenia)
What does PT measure?
PT - time it takes for plasma to clot after tissue factor is added
- it measures quality of extrinsic pathway of coagulation
What’s INR?
What type of shock a septic shock is?
Distributive
Sepsis 6 steps
What are normal levels of lactate?
•Normal range (unstressed patient): 0.5 - 1 mmol/L
- Critical illness patient’s normal value: less than 2 mmol/L
- Hyperlactatemia: 2 mmol/L and above
What’s lactate?
Lactate
- byproduct by anaerobic pathway
- indicates inceased glycolysis (used in anaerobic pathway of respiration), that cannot bind to H+ ions -> acidosis (as H+ concentration is increased)
Clinical presentation of lactic acidosis
nausea, vomiting, Kussmaul breathing (deep and laboured), weakness
Possible causes of lactic acidosis
causes: inborn error of metabolism, decreased tissue oxygenation (from low perfusion), medication or intoxication
What blood tests in Ix for sepsis?
Blood tests (sample obtained from two distinct sites) to test for:
- evidence of infection
- clotting problems
- abnormal liver or kidney function
- impaired oxygen availability
- electrolyte imbalances
What other tests do for sepsis (other than bloods/imaging)
Other tests - depend on the symptoms -> to on the body fluids such as:
- urine - in case of suspicion of UTI infection
- Wound secretions - in case of a wound appearing to be infected
- Respiratory secretions - if the mucous has been coughed out
Possible imaging tests in sepsis + justification
Imaging scans
- X ray - to visualise problems in the lungs
- CT - in case of infections in the appendix, pancreas or intestines
- USS- useful to check for the infections within the gallbladder or the ovaries
- MRI- useful in identifying soft tissue infections (e.g. abscess in the spine)
How much O2 to give in septic pt?
Give 15L of O2 (if sats <94%)
*in COPD aim for sats 88-92%
What type and how much IV fluids to give in sepsis?
give 500 ml IV bolus of crystalloid* (e.g. Hartmann’s)
If systolic BP is <90 mmHg -> give further boluses up to 30 ml/kg
If systolic BP remains <90 mmHg -> refer to critical care
*crystalloid - volume expander
What (other than antibiotics) med may be possible given in septic patient?
- vasopressors - if BP remains low after receiving IV fluids -> to constrict blood vessels and therefore increase BP
- Low doses of corticosteroids
- Insulin - to maintain stable blood sugar level
- Drugs that modify immune system responses
- Painkillers
- Sedatives
What blood tests to perform in septic patient?
- FBC
- Chem profile (U&E, LFT, calcium and phosphate)
- Bicarbonate
- C-reactive protein
- Glucose
- Clotting
- Lactate
- Arterial blood gas
Urine output monitoring in septic patient (frequency, aim)
- hourly
- fluid balance chart
- Possible catheter insertion (as more practical and accurate)
- Aim for: 0.5 ml/kg/hr
Criteria for the diagnosis of severe sepsis
If any of the following applies -> severe sepsis
- SBP <90 or MAP <65 (despite fluid resuscitation)
- supplemental O2 is required (FiO2 >0.5) to keep sats >90%
- INR is >1.5, APTT >60 seconds or platelets <100 (*aPTT - activated partial prothrombin time)
- urine output <0.5 ml/kg/hr
- lactate >2.0 mmol/hr
- immunosuppressed patient
What’s the fluid challenge?
Fluid challenge:
- Give 250 - 500 mls via 16g cannula
Interpet
- Measure pulse and blood pressure
If BP improves -> patient is hypovolaemic -> give further fluids
- Reasses
