Imputation of PaO2 From SaO2

March 4, 2022 updated by: Peter Chuanyi Hou, Brigham and Women's Hospital

Imputation of PaO2 From SaO2 in the Respiratory Component of the Sequential Organ Failure Assessment (SOFA) Score

The aims of this study are (1) to find out the relationship between PaO2 and SaO2 among mechanically ventilated patients and (2) to create a reliable system to utilize SF ratios to impute the PF ratios in assessing the respiratory parameter of the SOFA score.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The Sequential Organ Failure Assessment (SOFA) score is validated as a measure of severity of illness over time in intensive care unit (ICU) patients and can be used to follow the course of organ dysfunction and response to treatment1. SOFA has become a frequently used scoring system of patients in multi-organ failure, given its high sensitivity and specificity as a predictor of morbidity and mortality in critically ill patients2. The severity of respiratory dysfunction is measured in the SOFA score by PaO2/FiO2 (PF) ratio, which is also used as a measure of severity of hypoxemia in patients with acute respiratory distress syndrome (ARDS).

An invasive sampling of arterial blood gas (ABG) is required to measure the PaO2 for the PF. Often, patients with less severe hypoxemia may not clinically undergo ABG testing on a routine basis; hence the clinical and research utility of the SOFA scoring system is reduced. Furthermore, previous studies revealed concerns about anemia following repeated blood sampling; hence, the tendency to implement less invasive approaches have led to less frequent ABG measurements in critically ill patients3. However, almost all ICU patients are monitored with pulse oximeters, which measure the percent saturation of hemoglobin with oxygen (SpO2). Whether SpO2 can be used to impute PaO2 for determining the PF ratio has not been robustly evaluated in a prospective study of critically ill patients.

Prior work investigating the association between PaO2 and SpO2 includes a post hoc study of ARDS Network patients4. This study excluded patients at altitude, used a linear model for a highly non-linear relationship, and could not determine whether SpO2 and PaO2 were simultaneously measured. A similar approach was applied to ARDS Network patients to derive an SpO2-based respiratory subscore of the SOFA score5. Several similar, retrospective studies have been performed in mechanically ventilated children, consistently using linear models of correlation between SF and PF ratios, with similar limitations6-9.

The Ellis inversion10 of the Severinghaus equation11 provides a useful non-linear method for imputing PaO2 from SaO2. This technique has been used in multiple cohorts of patients with pneumonia12-14. This simple calculation can be improved by incorporating PaCO2 and pH values, which could be available from venous blood gases that may be obtained in patients without arterial catheters. Because Severinghaus/Ellis estimates SaO2, a method for estimating SaO2 from SpO2 is necessary. There is no current validated and reliable method for calculating SaO2 on the basis of a measured SpO2. Skin pigmentation affects accuracy of SpO2, as do sex and oximeter type15,16.

The aims of this study are (1) to find out the relationship between PaO2 and SaO2 among mechanically ventilated patients and (2) to create a reliable system to utilize SF ratios to impute the PF ratios in assessing the respiratory parameter of the SOFA score.

Study Type

Observational

Enrollment (Actual)

646

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • China
      • Beijing, China
        • PLA General Hospital
    • Guangdong
      • Guangzhou, Guangdong, China
        • Guangzhou red cross hospital
  • United States
    • Massachusetts
      • Boston, Massachusetts, United States, 02115
        • Brigham and Women's Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Adults > 18 years old who are invasively mechanically ventilated in an ED or ICU

Description

Inclusion Criteria:

  1. Mechanically ventilated patient in a participating ICU or ED.
  2. Arterial blood gas ordered and obtained for clinical reasons.

Exclusion Criteria:

  1. Age < 18 years
  2. Pregnancy
  3. Prisoners

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Cohort
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Imputation of SF to PF
Patients required invasive mechanical ventilation within 6 hours after intubation
Other: arterial blood gas
Just record clinical lab data
Other Names:
  • oxygena saturation

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
To evaluate the relationship between PaO2 and SaO2 among mechanically ventilated patients
Time Frame: one year
one year

Secondary Outcome Measures

Outcome Measure
Time Frame
To utilize SF ratios to impute the PF ratios in assessing the respiratory parameter of the SOFA score
Time Frame: one year
one year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Brigham and Women's Hospital

Collaborators

Chinese PLA General Hospital
Guangdong Provincial People's Hospital
Guangzhou Red Cross Hospital

Investigators

  • Principal Investigator: Peter C Hou, MD, Brigham and Women's Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

September 1, 2015

Primary Completion (Actual)

June 30, 2020

Study Completion (Actual)

December 31, 2020

Study Registration Dates

First Submitted

November 4, 2015

First Submitted That Met QC Criteria

November 4, 2015

First Posted (Estimate)

November 6, 2015

Study Record Updates

Last Update Posted (Actual)

March 8, 2022

Last Update Submitted That Met QC Criteria

March 4, 2022

Last Verified

March 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2015P001945

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Acute Respiratory Failure

Clinical Trials on arterial blood gas

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Mongolia

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

3
Subscribe