infection: acute sepsis Flashcards
what is sepsis?
life-threatening organ dysfunction due to a dysregulated host response to infection
what is septic shock?
persisting hypotension requiring treatment to maintain blood pressure DESPITE fluid resuscitation
what is bacteraemia?
presence of bacteria in the blood (+/- clinical features)
what is septicaemia?
generalised sepsis
how do you recognise sepsis?
using EWS (early warning score): high RR, high HR, high temp, LOW BP
and clinical features suggesting source e.g. pneumonia, UTI, meningitis etc.
what do you do if the patient has red flag sepsis?
send urgent investigations, inform senior doctor complete sepsis 6 bundle: oxygen IV antibiotics fluids blood cultures urine output lactate (anaerobic respiration, from hypoxic, BP drop)
what are the urgent investigations to be carried out if a patient has red flag sepsis?
FBC, U&E blood sugar LFT (liver function) - AST & ALT CRP ABC - measure pCO2, pO2 etc. other microbiology samples (CSF, urine) EDTA bottles for PCR (prevents blood clotting in bottle)
what is the likely diagnosis of red flag sepsis?
Meningococcal meningitis (Neisseria meningitidis)
spread by direct contact with resp secretions
most people have harmless colonisation
can be rapidly progressive
what is the structure of Neisseria meningitidis which causes the symptoms?
- lipopolysaccharide ENDOTOXIN triggers inflammation
- PILUS enhances attachment
- POLYsaccharide Capsule: promotes adherence & prevents phagocytosis
what is the inflammatory cascade of from infection leading to sepsis?
- endotoxin binds to macrophages
- local effects - inflammatory response (cytokines)
- systemic - try to control infection (cytokines circulation)
- sepsis - infection not controlled
describe local step of inflammatory cascade
cytokines (TNF-a & IL-1) stimulates inflammatory response to promote wound repair & recruit macrophages etc.
INFLAMMATION & WOUND REPAIR
describe systemic step of inflammatory cascade
cytokines released into circulation
stimulate GF, macrophages & platelets to try and control infection
what happens in sepsis? (inflammatory cascade from local to systemic)
infection NOT controlled
cytokines lead to activation of HUMORAL cascade
Circulatory insult (DIC & organ injury)
describe the relationship between sepsis and coagulation
- cytokines initiate production of thrombin –> coagulation
- cytokines inhibit fibrinolysis (breakdown clot)
- coagulation cascade leads to microvascular thrombosis –> organ ischaemia, dysfunction & failure
what is microvascular injury the major cause of?
shock & multiorgan failure
coagulation cascade –> microvascular thrombosis –> organ ischaemia –> progress to necrosis
what are the specific treatments of sepsis?
- antimicrobials
2. surgery - drainage, debridement, dead space removal
what are the support treatment of sepsis?
symptom relief
physiological restoration
(consider early referral to ITU, sepsis 6, regular monitoring & reassessment)
what is the antibiotic treatment used in sepsis?
agent that is active against Neisseria meningitides (can penetrate into CSF)
CEFTRIAXONE (a type of ß-lactam, cephalosporin - cell wall)
what are the life-threatening complications of sepsis?
irreversible hypotension
respiratory failure
AKI
raised intracranial pressure (IV (?) mannitol)
ischaemic necrosis of digits / hands / feet
how do you confirm the diagnosis of sepsis?
blood culture
PCR of blood
lumbar puncture CSF (IF SAFE) - microscopy & culture of CSF, PCR of CSF - always check contraindications (if harmful to patient)
how do you examine the CSF?
urgent transport of CSF to lab - glucose & protein estimation, microscopy, culture appearance - turbid, colour microscopy WBC, RBC gram stain (-ve for N. meningitides) refer for PCR
describe meningococcus
Neisseria meningitidis - gram neg Diplococci
lots of serogroups (A, B, C) - based on polysaccharide - mainly B
capsular antigen (evades immune response by preventing phagocytosis)
outer membrane acts as endotoxin - triggering inflammation
spread by aerosols & nasopharyngeal secretions
what are the preventions against menigococcus?
- vaccination (serogroup B)
2. antibiotic prophylaxis (notifiable disease, close contacts can be given antibiotic prophylaxis & vaccination)