horowitz_index_pf_ratio: Horowitz Index (P/F Ratio) for Lung Function

In cliot: Clinical Indices and Outcomes Tools

Horowitz Index (P/F Ratio) for Lung Function

Description

Calculates the Horowitz Index, also known as the P/F ratio (PaO2/FiO2). This index is a widely used clinical indicator of lung function and is central to the Berlin Definition of Acute Respiratory Distress Syndrome (ARDS). It assesses the degree of hypoxemia.

Usage

horowitz_index_pf_ratio(pao2_mmhg, fio2_percent)

Arguments

pao2_mmhg	Numeric. Arterial partial pressure of oxygen in mmHg.
fio2_percent	Numeric. Fraction of inspired oxygen expressed as a percentage (e.g., 21 for room air, 40 for 40%).

Value

A list containing:

Horowitz_Index	The calculated P/F ratio.
ARDS_Severity	Classification based on Berlin criteria (Normal >300, Mild 200-300, Moderate 100-200, Severe <=100).

References

Horovitz JH, Carrico CJ, Shires GT. Pulmonary response to major injury. Arch Surg. 1974;108(3):349-355. The ARDS Definition Task Force. Acute Respiratory Distress Syndrome: The Berlin Definition. JAMA. 2012;307(23):2526-2533.

Examples

# Example 1: Severe ARDS
# PaO2 60 mmHg on 80% FiO2
# Ratio = 60 / 0.8 = 75
horowitz_index_pf_ratio(60, 80)

# Example 2: Normal Lung Function
# PaO2 95 mmHg on Room Air (21%)
# Ratio = 95 / 0.21 = 452
horowitz_index_pf_ratio(95, 21)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.