---
title: "pf_ratio"
description: "Ratio between the partial pressure of oxygen in blood (PaO₂) and the fraction of oxygen in the inhaled air (FiO₂)."
---

Ratio between the partial pressure of oxygen in blood (PaO₂) and the fraction of oxygen in the inhaled air (FiO₂).

**Purpose.** Use to record the ratio between the partial pressure of oxygen in blood (PaO₂) and the fraction of oxygen in the inspired air (FiO₂).

## Source

| Model | Leg | Role |
|---|---|---|
| `openEHR-EHR-OBSERVATION.pf_ratio.v1` | openEHR | defines this table |

## Columns

| Column | Type | Null | Description | Source |
|---|---|---|---|---|
| `id` | `uuid primary key` | no | Primary key. | — |
| `form_id` | `uuid` → [`form`](/docs/tables/form) | no | The form this entry was recorded on. | — |
| `form_block_id` | `uuid` | yes | The block within the form, when the entry is bound to one. | — |
| `ratio_magnitude`<br />`ratio_units` | quantity<br />`numeric`, `text` | yes | Ratio | `/data[at0001]/events[at0002]/data[at0003]/items[at0004]` |
| `clinical_interpretation`<br />`clinical_interpretation_code`<br />`clinical_interpretation_system`<br />`clinical_interpretation_valueset_id` | coded text<br />`text`, `text`, `text`, `text` | yes | Clinical interpretation | `/data[at0001]/events[at0002]/data[at0003]/items[at0007]` |
| `comment` | `text` | yes | Comment | `/data[at0001]/events[at0002]/data[at0003]/items[at0008]` |
| `confounding_factors` | `text` | yes | Confounding factors | `/data[at0001]/events[at0002]/state[at0009]/items[at0010]` |

## Constraints

```sql
check ((ratio_magnitude is null and ratio_units is null) or (ratio_magnitude is not null and ratio_units is not null))
check ((clinical_interpretation_code is null and clinical_interpretation_system is null and clinical_interpretation_valueset_id is null) or (clinical_interpretation is not null and clinical_interpretation_code is not null and clinical_interpretation_system is not null and clinical_interpretation_valueset_id is not null))
```

## Unique

- `form_block_id`

## References

| Columns | Target | On delete |
|---|---|---|
| `form_id` | [`form`](/docs/tables/form) | cascade |
| `form_id, form_block_id` | [`form_block`](/docs/tables/form_block) | cascade |
| `clinical_interpretation_valueset_id, clinical_interpretation_code, clinical_interpretation_system, clinical_interpretation` | [`valueset_code`](/docs/tables/valueset_code) | restrict |

## Indexes

- `pf_ratio_form_id_idx` on `form_id`