Aliyu MB. Efficiency of boolean search strings for information retrieval. Am J Eng Educ. 2017; 6:(11)216-222

Bhat K, Takoor P. CINAHL Plus with full-text database utilisation by nursing professionals: a study at KMC Health Sciences Library, Manipal. Pearl: a Journal of Library and Information Science. 2014; 8:(4)

Critical Appraisal Skills Programme. CASP. 2018. https// (accessed 8 September 2022)

Cully M, Treut M, Thompson AD, DePiero AD. Exhaled end-tidal carbon dioxide as a predictor of lactate and pediatric sepsis. Am J Emerg Med. 2020; 38:(12)2620-2624

Dunn K, Marshall JG, Wells AL, Backus JEB. Examining the role of MEDLINE as a patient care information resource: an analysis of data from the Value of Libraries study. J Med Libr Assoc. 2017; 105:(4)336-346

Flenady T, Dwyer T, Applegarth J. Accurate respiratory rates count: So should you!. Australas Emerg Nurs J. 2017; 20:(1)45-47

Gotts JE, Matthay MA. Sepsis: pathophysiology and clinical management. BMJ. 2016; 353

Goulden R, Hoyle MC, Monis J qSOFA, SIRS and NEWS for predicting inhospital mortality and ICU admission in emergency admissions treated as sepsis. Emerg Med J. 2018; 35:(6)345-349

Gyawali B, Ramakrishna K, Dhamoon AS. Sepsis: the evolution in definition, pathophysiology, and management. SAGE Open Med. 2019; 7

Hunter CL, Silvestri S, Dean M, Falk JL, Papa L. End-tidal carbon dioxide is associated with mortality and lactate in patients with suspected sepsis. Am J Emerg Med. 2013; 31:(1)64-71

Hunter CL, Silvestri S, Ralls G, Stone A, Walker A, Papa L. A prehospital screening tool utilizing end-tidal carbon dioxide predicts sepsis and severe sepsis. Am J Emerg Med. 2016; 34:(5)813-819

Hunter CL, Silvestri S, Ralls G Comparing quick sequential organ failure assessment scores to end-tidal carbon dioxide as mortality predictors in prehospital patients with suspected sepsis. West J Emerg Med. 2018; 19:(3)446-451

Kamel KS, Oh MS, Halperin ML. L-lactic acidosis: pathophysiology, classification, and causes; emphasis on biochemical and metabolic basis. Kidney Int. 2020; 97:(1)75-88

Levy MM, Fink MP, Marshall JC 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis Definitions Conference. Intensive Care Med. 2003; 29:(4)530-538

McGillicuddy DC, Tang A, Cataldo L, Gusev J, Shapiro NI. Evaluation of end-tidal carbon dioxide role in predicting elevated SOFA scores and lactic acidosis. Intern Emerg Med. 2009; 4:(1)41-44

Clinical tools. 2021. https// (accessed 8 September 2022)

Pishbin E, Ahmadi GD, Sharifi MD, Deloei MT, Shamloo AS, Reihani H. The correlation between end-tidal carbon dioxide and arterial blood gas parameters in patients evaluated for metabolic acid-base disorders. Electron Physician. 2015; 7:(3)1095-1101

NEWS update: recognising severe sepsis. National Early Warning Score (NEWS) 2. Standardising the assessment of acute-illness severity in the NHS. 2017; 22-24

Seymour CW, Liu VX, Iwashyna TJ Assessment of clinical criteria for sepsis: for the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis–3). JAMA. 2016; 315:(8)762-774

Seymour CW, Gesten F, Prescott HC Time to treatment and mortality during mandated emergency care for sepsis. N Engl J Med. 2017; 376:(23)2235-2244

Singer M, Deutschman CS, Seymour CW The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis–3). JAMA. 2016; 315:(8)801-810

Taghizadieh A, Pouraghaei M, Moharamzadeh P, Ala A, Rahmani F, Basiri Sofiani K. Comparison of end-tidal carbon dioxide and arterial blood bicarbonate levels in patients with metabolic acidosis referred to emergency medicine. J Cardiovasc Thorac Res. 2016; 8:(3)98-101

UK Sepsis Trust. References and sources. 2022. https// (accessed 8 September 2022)

Valente T. Capnography, king of the ABC's.Bloomington (IN): iUniverse; 2010

Weiss SJ, Guerrero A, Root-Bowman C Sepsis alerts in EMS and the results of pre-hospital EtCO2. Am J Emerg Med. 2019; 37:(8)1505-1509

Wiryana M, Sinardja I, GedeBudiarta I, Widnyana I, Aryabiantara W, Paramasari A. Correlation of end tidal CO2 (EtCO2) level with hyperlactatemia in patient with hemodynamic disturbance. J Anesth Clin Res. 2017; 8

To what extent is end-tidal carbon dioxide a predictor of sepsis?

02 October 2022
Volume 14 · Issue 10



Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. It is a major cause of death worldwide; 245 000 cases are reported in the UK annually with a mortality rate of 20.3%. Rapid diagnosis and rapid treatment of sepsis can significantly reduce mortality but sepsis can be difficult to diagnose. End-tidal carbon dioxide (EtCO2) is the measurement of expired CO2 using capnometry and waveform capnography. For CO2 to be exhaled, it must be metabolised and transported before being exhaled by effective ventilation; EtCO2 can therefore provide an indication of metabolism, circulation and ventilation. EtCO2 has already been shown to be an indicator of other metabolic acidosis conditions so this review aims to identify the usefulness of EtCO2 in identifying sepsis.


A systematic literature search was conducted between March and April 2021 using the CINAHL Plus and MEDLINE databases. The results were screened and evaluated.


Of the 44 papers identified in the original search, seven were included in this review.


This review suggests an EtCO2 of ≤25 mmHg (3.3 kPa) in patients with a suspected infection is diagnostic of sepsis and therefore could be used to increase the speed and accuracy of diagnosis and potentially reduce sepsis mortality. It also identifies gaps in research around UK practice and in comparing EtCO2 against UK sepsis guidelines and diagnostic tools such as the UK Sepsis Trust guidelines.

The Third International Consensus defines sepsis as a ‘life-threatening organ dysfunction caused by a dysregulated host response to infection’ (Singer et al, 2016). Sepsis is a leading cause of death in the UK with 245 000 cases reported annually with a mortality rate of 20.3% (close to 50 000 deaths); globally, there are 49 million cases with 11 million deaths per year (UK Sepsis Trust, 2022).

Sepsis causes a multitude of pathological cascades, which lead to end-organ damage and homeostatic imbalances (Singer et al, 2016). These cascades lead to increased lactate production.

During the progression of sepsis, cardiovascular dysfunction because of septic shock begins to lead to systemic hypoperfusion and respiratory dysfunction (Gyawali et al, 2019). Tissue permeability caused by the cardiovascular dysfunction around the lungs leads to pulmonary oedema causing a ventilation–perfusion mismatch, resulting in hypoxia (Gotts and Matthay, 2016).

Subscribe to get full access to the Journal of Paramedic Practice

Thank you for visiting the Journal of Paramedic Practice and reading our archive of expert clinical content. If you would like to read more from the only journal dedicated to those working in emergency care, you can start your subscription today for just £48.

What's included

  • CPD Focus

  • Develop your career

  • Stay informed