What are the criteria to meet a diagnosis of systemic inflammatory response syndrome (SIRS)? Can you name a scoring system?
Sepsis remains one of the main causes of morbidity and mortality in the critically ill patient and this is despite of modern antibiotics and resuscitation techniques.
Improvements in mortality rates have occurred because of a more focus being placed on early detection. So, it would seem the low hanging fruit would be to develop a more nuanced diagnostic criteria to help the clinician initiate early treatment.
Sepsis is caused by a dysregulated immune response to an infection which can progress to life-threatening organ dysfunction (Singer M 2016). This new definition was adopted in 2016. Previous definitions described sepsis as a systemic inflammatory response syndrome [SIRS] arising due to a new infection. The reason for the adoption of this new definition will be discussed below in addition to outlining the old diagnostic criteria associated with SIRS.
Sepsis itself should always be suspected when presented with an acutely deteriorating patient in whom there is clinical evidence or strong suspicion of infection. Sepsis is extremely dangerous which can cause a rapid deterioration in the patient and hence there should always be a low threshold for suspicion of sepsis.
The diagnosis of sepsis itself is difficult because there is no single biomarker to identify that a patient has sepsis, this is where clinical judgment comes in. To aid the clinician several diagnostic tools or scoring systems such as a validated scoring system, such as the National Early Warning Score 2 (NEWS2). There are multiple scoring systems and definitions for sepsis and sepsis with organ dysfunction. None is perfect and many seek to measure similar variables.
Due to the heterogeneity of the disease process the diagnosis and definition of sepsis has been difficult to pin done and has undergone a series of revisions of the years.
A 1991 consensus conference developed initial definitions that systemic inflammatory response syndrome (SIRS) to infection would be called sepsis (Bone RC 1992)Since 1992 the Systemic Inflammatory Response Syndrome (SIRS) criteria have been used for diagnosis.
The new definition abandoned use of host inflammatory response syndrome criteria (SIRS) in identification of sepsis and abandoned the use of the term severe sepsis. Sepsis complicated by organ dysfunction was termed severe sepsis, which could progress to septic shock, defined as “sepsis-induced hypotension persisting despite adequate fluid resuscitation.”
An earlier sepsis definition, Sepsis-1, was developed at a 1991 consensus conference (Bone RC 1992) in which SIRS criteria were established.
Four SIRS criteria were defined:
- tachycardia (heart rate >90 beats/min),
- tachypnoea (respiratory rate >20 breaths/min),
- fever or hypothermia (temperature >38 or <36 °C), and
- leucocytosis, leukopenia, or bandemia (white blood cells >1,200/mm3, <4,000/mm3 or bandemia ?10%).
For a patient to be diagnosed with SIRS they would have to meet two or more of these criteria, while Sepsis-1 was defined as infection or suspected infection leading to the onset of SIRS.
Levy MM recognised the limitations with these definitions, and expanded the list of diagnostic criteria, which resulted in the introduction of Sepsis-2, which incorporated the threshold values for organ damage.
Therefore, in order to be diagnosed with sepsis under the Sepsis-2 definition, as with Sepsis-1, an individual must have at least 2 SIRS criteria and a confirmed or suspected infection (Peach BC. 2016.). Hence for more than two decades the definitions of sepsis and septic shock remained unchanged.
Sepsis-3 arose after a 2016 task force was convened by national societies including the Society of Critical Care Medicine (SCCM) and the European Society of Intensive Care Medicine (ESICM) (Singer 2016). The new proposal defines sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection (Seymour CW 2016).
The task force compared traditional SIRS criteria to other methods, including the Logistic Organ Dysfunction System (LODS) and Sequential Organ Failure Assessment (SOFA) scoring. The outcome was that the task force favoured the use of SOFA to assess the severity of organ dysfunction in a potentially septic patient
Sepsis was redefined by Sepsis-3 as “life-threatening organ dysfunction caused by a dysregulated host response to infection” (Singer 2016)
Organ dysfunction is defined as a change of 2 or more points in the Sequential (or Sepsis-related) Organ Failure Assessment (SOFA) score (Singer 2016)
Previous definitions which described sepsis as a systemic inflammatory response syndrome (SIRS) caused by an infection were superseded by the Sepsis-3 definition
Also with the revised definitions, severe sepsis, which was defined as sepsis associated with organ dysfunction, hypoperfusion, or hypotension, (septic shock was defined as sepsis with hypotension despite adequate fluid replacement (NICE)) was made redundant with the new 2016 sepsis-3 definition.
The 2016 consensus document describes organ dysfunction as an acute increase in total Sequential Organ Failure Assessment (SOFA) score two points consequently to the infection. The task force also introduced qSOFA to help identify patients outside of CCU patients with suspected infection who are likely to develop sepsis. (Gul 2017)
NEWS2
NEWS2 is the latest version of the National Early Warning Score (NEWS). It was first introduced in 2012 and was then subsequently updated in December 2017. It is based on a simple aggregate scoring system in which a score is allocated to physiological measurements.
Six simple physiological parameters form the basis of the scoring system:
- respiration rate
- oxygen saturation
- systolic blood pressure
- pulse rate
- level of consciousness or new confusion*
- temperature.
References:
- Bone RC, Balk RA, Cerra FB, et al. Definitions for Sepsis and Organ Failure and Guidelines for the Use of Innovative Therapies in Sepsis. Chest 1992; 101:1644-55. 10.1378/chest.101.6.1644
- Gaddis ML, Gaddis GM. Detecting Sepsis in an Emergency Department: SIRS vs. qSOFA. Mo Med. 2021 May-Jun;118(3):253-258. PMID: 34149086; PMCID: PMC8210984.
- Gül F, Arslanta? MK, Cinel ?, Kumar A. Changing Definitions of Sepsis. Turk J Anaesthesiol Reanim. 2017 Jun;45(3):129-138. doi: 10.5152/TJAR.2017.93753. Epub 2017 Feb 1.
- Levy MM, Fink MP, Marshall JC, et al. 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis Definitions Conference. Crit Care Med 2003; 31:1250-6. 10.1097/01.CCM.0000050454.01978.3B
- NHS England. Sepsis guidance implementation advice for adults. September 2017
- National Institute for Health and Care Excellence. Sepsis: recognition, diagnosis and early management. September 2017
- Peach BC. Implications of the new sepsis definition on research and practice. J Crit Care 2017; 38:259-62. 10.1016/j.jcrc.2016.11.032
- Seymour CW, Liu VX, Iwashyna TJ, et al. Assessment of Clinical Criteria for Sepsis: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA 2016; 315:762-74. 10.1001i
- Singer M, Deutschman CS, Seymour CW, et al. The third international consensus definitions for sepsis and septic shock (Sepsis-3). JAMA. 2016 Feb 23;315(8):801-10.
- Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA 2016; 315:801-10. 10.1001/jama.2016.0287
