Overview		Monitoring the patient's progress
Definitions of 'Sepsis' and 'Systemic Inflammatory Response Syndrome'		Preventing complications
Initial assessment and management		Ethical issues and resource allocation
Secondary assessment		Appendix
Treatment of the underlying problem		Further Reading
Theraputic strategies for preserving organ function

Definitions of 'Sepsis' and 'Systemic Inflammatory Response Syndrome'

Patients are often described as being "septic" or having "septic shock". These terms are used in a variety of ways by different doctors and in 1992 'sepsis' and several new terms were formally defined:

1. Systemic inflammatory response syndrome (SIRS) replaced the previous term 'sepsis syndrome'. This is the body's response to a variety of severe clinical insults. It is characterised by the presence of two or more of the following features:
   • Temperature >38°C or <36°C
   • Heart rate > 90/min
   • Respiratory rate > 20/min or PaCO2 <4.3kPa
   • White cell count > 12 x 10⁹/l
2. Sepsis is defined as SIRS in response to infection.
3. Severe sepsis is sepsis associated with:
   • organ dysfunction (altered organ function such that normal physiology cannot be maintained without support)
   • hypotension (systolic blood pressure < 90mmHg or a reduction of > 40 mmHg from the patient's normal in the absence of other causes of hypotension)
   • organ hypoperfusion (revealed by signs such as lactic acidosis, oliguria, acute alteration of mental status).
4. Septic shock describes sepsis with hypotension despite adequate fluid resuscitation.
5. Multiple organ dysfunction syndrome (MODS) describes a state where dysfunction is seen in several organs.
   In this article the term SIRS is used. The clinical appearance of a patient with SIRS resulting from infection (sepsis) or other causes (such as burns or pancreatitis) is similar. However there will be differences in the management of the different underlying problem. The initial approach to looking after these patients is similar. 

Initial assessment and management

Initial management of a critically ill patient includes:

• Immediate assessment of the airway, breathing and circulation
• A brief history
• A limited examination of the relevant systems of the body.
• A secondary assessment after stabilisation of the patient including a more thorough history, detailed examination by system and appropriate investigations.

Initial Management

Airway and breathing. Respiratory failure is common and may develop at any stage so repeated assessments are necessary. A depressed conscious level is the most common cause of airway obstruction. Patients with inadequate airway reflexes should be nursed in the recovery position and if possible intubated and mechanically ventilated.

A clear airway does not indicate effective breathing. Failure of gas exchange may be caused by lung parenchymal problems (pneumonia, lung collapse, pulmonary oedema), failure of the mechanics of ventilation (pneumothorax, haemothorax, airway rupture) or reduced respiratory drive (encephalopathy).

Respiratory failure is suggested by signs of respiratory distress including dyspnoea, increased respiratory rate, use of accessory muscles, cyanosis, confusion, tachycardia, sweating. The diagnosis is made clinically but may be confirmed by pulse oximetry and arterial blood gases. Patients with a depressed conscious level may not react normally to hypoxia and signs of respiratory failure may be difficult to detect. Patients with inadequate ventilation, gas exchange or both require ventilatory support. This usually necessitates intubation and mechanical ventilation although in some patients gas exchange and oxygenation can be improved by the application of continuous positive airway pressure (CPAP) by face mask or non-invasive ventilation.

Circulation. Tachycardia and hypotension are almost universal findings in the septic patient and result from a number of cardiovascular problems. In early sepsis, and in patients who have been partially or fully fluid resuscitated, the low blood pressure and high heart rate are associated with a high cardiac output and a low peripheral vascular resistance with warm peripheries and bounding pulses. In contrast, patients who have not been significantly resuscitated or have presented late in the course of their illness have a low cardiac output and high systemic vascular resistance. These patients are peripherally cold, sweaty, with weak, thready pulses and they need urgent resuscitation. Many patients present with an unclear or mixed clinical picture. However resuscitation aims to restore circulating volume, cardiac output and reversal of hypotension.

Initially infuse i/v crystalloid or colloid rapidly guided by the clinical response. In a peripherally warm, vasodilated patient with a high cardiac output several litres of crystalloid may be needed to establish adequate intravascular filling. In patients with a mixed or unclear clinical picture, clinical assessment may be difficult. Administering large volumes of fluid to patients with known cardiac disease or myocardial dysfunction related to their acute illness is a problem. In these patients insertion of a central venous catheter will help by measuring the central venous pressure (CVP) to guide fluid resuscitation and to provide a route for infusion of vasopressors or inotropes. A one-off reading of CVP may be misleading but following a trend of measurements and their response to fluid challenges is helpful - see Update in Anaesthesia No 12. Urine output should be charted hourly.

History. The primary insult may be self-evident (eg trauma, burns, recent surgery) or more difficult to diagnose (eg pancreatitis, gynaecological sepsis), particularly in unconscious patients.

Examination. The appearance of the patient is variable; they may appear well, warm and well-perfused with bounding pulses or may be cold, vasoconstricted and peripherally cyanosed. The "warm" and "cold" patients represent two ends of a spectrum of presentations. The examination will reflect the degree of their illness, their state of intravascular hydration and may reveal the underlying cause.

When looking for an underlying source of infection consider:

• Central nervous system: Global (sleepiness, confusion, agitation, coma) or focal (localised abnormality of movement or sensation) neurological dysfunction suggesting meningitis, encephalitis, cerebral malaria or abscess.
• Respiratory system: Mucopurulent discharge from the respiratory tract, dyspnoea, lung consolidation or pleural fluid collection.
• Gastrointestinal tract: Abdominal pain with guarding and rigidity suggesting peritoneal irritation.
• Vaginal discharge or history of termination suggest gynaecological sepsis
• Skin: Purulent skin wound, signs of inflammation (redness, pain, swelling, heat) or petechial rash (meningococcaemia).
• The patient with SIRS may have a number of other, non-infective diagnoses. Consider myocardial infarction, pulmonary embolism, diabetic ketoacidosis, poisoning or drug overdose, eclampsia, cerebrovascular event.
• In some patients the diagnosis is unclear at this stage and treatment has to continue along "best guess" lines. 

(Continued ...)

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