Unreliability of oxygen tension-based indices in reflecting intrapulmonary shunting in critically ill patients

Critical Care Medicine
R D CaneK Walther

Abstract

Measurement of intrapulmonary shunting (Qsp/Qt), a widely used method for monitoring disturbances of pulmonary oxygen transfer in critically ill patients, involves calculation of arterial and mixed venous oxygen contents. In circumstances where mixed venous blood samples are not readily available, oxygen tension-based indices such as the alveolar to arterial oxygen tension differences (P[A-a]O2), arterial oxygen tension to alveolar oxygen tension ratio (PaO2/PAO2), PaO2 to FIO2 ratio (PaO2/FIO2) and respiratory index (RI) are widely utilized to reflect Qsp/Qt. Oxygen content-based indices such as the estimated shunt are not as widely utilized as the oxygen tension indices. In 75 critically ill patients in whom a pulmonary artery catheter was being utilized to augment clinical care, comparisons were made between Qsp/Qt and P(A-a)O2, PaO2/PAO2, PaO2/FIO2, RI, and estimated shunt to determine which index best reflected Qsp/Qt. Correlations between Qsp/Qt and estimated shunt were good (r = .94) and poor for the P(A-a)O2 (r = .62), PaO2/PAO2 (r = .72), PaO2/FIO2 (r = .71), and RI (r = .74). We conclude that there are no real substitutes for venous oxygen contents in critically ill patients. When pulmonary artery blood is not availab...Continue Reading

Citations

Apr 1, 1991·Canadian Journal of Anaesthesia = Journal Canadien D'anesthésie·W A Tweed, T L Lee
Jul 31, 1999·Archives of Medical Research·I Maulen-RadovanM Márquez Aguirre
Jan 1, 1997·Critical Care Medicine·M S Gowda, R A Klocke
Jun 10, 2003·Pediatric Critical Care Medicine : a Journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies·Luigi GagliardiFabio Mosca
Jan 1, 1995·Acta Anaesthesiologica Scandinavica. Supplementum·J H Wandrup
Jan 1, 1993·Intensive Care Medicine·A Frutiger, J X Brunner
Jan 1, 1990·Intensive Care Medicine·P Nightingale
Nov 1, 1991·Canadian Journal of Anaesthesia = Journal Canadien D'anesthésie·W A TweedT L Lee
Jan 1, 1990·Scandinavian Journal of Clinical and Laboratory Investigation. Supplementum·B A Shapiro
Jan 16, 2013·Critical Care Medicine·Andreas W ReskeMarcelo B P Amato
May 16, 2006·Mathematical Biosciences·Jonathan P Whiteley
Sep 28, 2001·British Journal of Anaesthesia·C E Hahn
Aug 14, 2002·British Journal of Anaesthesia·Jonathan P WhiteleyC E Hahn
Mar 31, 2005·Physiological Measurement·Philip J PeytonBruce Thompson
Jun 1, 1999·Canadian Journal of Anaesthesia = Journal Canadien D'anesthésie·M SeearP Skippen
Aug 21, 2019·Intensive Care Medicine Experimental·Emma M ChangJ Kenneth Baillie

Related Concepts

Implantable Catheters
Care of Intensive Care Unit Patient
Use-Effectiveness
Monitoring, Physiologic
Dioxygen
Pulmonary Gas Exchange

Trending Feeds

COVID-19

Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Alzheimer's Disease: MS4A

Variants within the membrane-spanning 4-domains subfamily A (MS4A) gene cluster have recently been implicated in Alzheimer's disease in genome-wide association studies. Here is the latest research on Alzheimer's disease and MS4A.

Pediculosis pubis

Pediculosis pubis is a disease caused by a parasitic insect known as Pthirus pubis, which infests human pubic hair, as well as other areas with hair including eye lashes. Here is the latest research.

Rh Isoimmunization

Rh isoimmunization is a potentially preventable condition that occasionally is associated with significant perinatal morbidity or mortality. Discover the latest research on Rh Isoimmunization here.

Genetic Screens in iPSC-derived Brain Cells

Genetic screening is a critical tool that can be employed to define and understand gene function and interaction. This feed focuses on genetic screens conducted using induced pluripotent stem cell (iPSC)-derived brain cells. It also follows CRISPR-Cas9 approaches to generating genetic mutants as a means of understanding the effect of genetics on phenotype.

Enzyme Evolution

This feed focuses on molecular models of enzyme evolution and new approaches (such as adaptive laboratory evolution) to metabolic engineering of microorganisms. Here is the latest research.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.

Pharmacology of Proteinopathies

This feed focuses on the pharmacology of proteinopathies - diseases in which proteins abnormally aggregate (i.e. Alzheimer’s, Parkinson’s, etc.). Discover the latest research in this field with this feed.

Alignment-free Sequence Analysis Tools

Alignment-free sequence analyses have been applied to problems ranging from whole-genome phylogeny to the classification of protein families, identification of horizontally transferred genes, and detection of recombined sequences. Here is the latest research.