Page 25 - Medicine and Surgery

P1: JYS
BLUK007-01 BLUK007-Kendall May 12, 2005 17:17 Char Count= 0

Chapter 1: Infections 21

Septicaemia and septic shock lipoteichoic acid (gram-positive bacteria) cause the pro-
duction and release of proinflammatory cytokines from
Definitions macrophages, monocytes and neutrophils. These in-
Bacteria in the blood can produce a wide spectrum of clude interleukin (IL)-1, IL-5, IL-6, IL-8, IL-11, IL-15
clinical entities from mild physiological abnormalities and tumour necrosis factor (TNF)-α.Complement ac-
to septic shock. tivation causes further tissue damage and widespread
Bacteraemia is a transient asymptomatic presence of
activation of the coagulation cascade results in dissemi-
organisms in the blood. nated intravascular coagulation (DIC). Hypotension re-
Septicaemia is used to describe organisms multiplying
sults from widespread induction of nitric oxide causing
in blood causing symptoms. There is a systemic in- ageneralised vasodilation. Cellular damage may occur
flammatory response syndrome (SIRS) clinically de- through a combination of ischaemia, direct cytopathic
fined by pyrexia, tachycardia, and leucocytosis. The damage and apoptosis.
term sepsis syndrome refers to the additional presence
of inadequate organ function/perfusion (confusion, Clinical features
hypoxaemia, raised lactate or oliguria). The systemic inflammatory response syndrome is de-
Septic shock refers to the presence of severe sepsis with
fined as follows:
associatedhypotensionandorgandysfunctiondespite Temperature over 38˚C or less than 36˚C.
adequate fluid resuscitation. Heart rate over 90 beats per minute.

Respiratory rate over 20 breaths per minute or PaCO 2
Aetiology more than 4.3 kPa.
9
9
Risk factors for development of sepsis include increasing WBC over 12 × 10 /L or less than 4 × 10 /L, or >10%
age, immunodeficiency, liver damage and malignancy. immature (band) forms.
Specific causes include Organ hypoperfusion may manifest as altered mental
direct introduction of bacteria into the blood stream state, lactic acidosis or oliguria. Systemic hypotension

viaperipheral or central intravenous line (Staph. epi- is defined as a systolic blood pressure below 90 mmHg
dermidis), or a reduction of more than 40 mmHg from baseline.
gastrointestinal perforation, rupture or ischaemia Patients may go on to develop multiorgan dysfunction

leadingtobacterialtranslocation(E.coli,Streptococcus including acute respiratory distress syndrome, dissem-
faecalis, anaerobic organisms), inated intravascular coagulation, hepatic failure, renal
bacteraemia arising from the urinary tract including failure and confusion or coma.

pyelonephritis, renal abscess, acute prostatitis (E. coli,
Klebsiella aerogenes, Proteus mirabilis), Investigations
overwhelming pneumococcal infection in patients Blood and where appropriate, urine, stool, pus and CSF

with impaired or absent splenic function (Streptococ- should be sent for culture prior to starting treatment
cus pneumoniae), whenever possible. Full blood count, glucose, urea and
meningococcaemiafromarespiratorysourcemayalso electrolytes, liver function tests, arterial blood gases and

result in sepsis with or without associated meningitis coagulation screen should be sent and repeated regularly
(Neisseria meningitidis), until the patient is stable.
patients with surgical site infections (Staph. aureus, E.

coli, anaerobes) and Management
burns (Staph. aureus, Streptococci, Pseudomonas). Aggressive resuscitation is essential. Airway patency

and oxygenation must be maintained and may require
Pathophysiology theuseofanoropharyngealairwayorendotrachealin-
The normal mechanisms involved in overcoming in- tubation. Blood pressure support involves aggressive
fection become detrimental when the infection is fluid replacement via wide bore canulae with care-
generalised. Bacteria cell wall components such as ful monitoring. CVP measurement allows assessment
lipopolysaccharide (gram-negative bacteria), peptido- of fluid resuscitation, and the response of the CVP
glycan (gram-positive and gram-negative bacteria) and to fluid challenge helps guide further resuscitation.