Health
A-a Gradient (Alveolar-Arterial O₂)
Calculate the alveolar-arterial O₂ gradient to distinguish hypoxemia causes. PAO₂ = FiO₂×(P_atm−47) − PaCO₂/0.8; A-a = PAO₂ − PaO₂. Normal ≈ (Age+10)/4. Elevated → V/Q mismatch, shunt, diffusion impairment. Derived from StatPearls, LITFL, Cornell PICU, and Martin 1999. Not medical advice.
Quick start
Call this tool from your code in three languages.
curl -X POST 'https://api.elysiatools.com/en/api/tools/a-a-gradient-calculator' \
-H 'Content-Type: application/json' \
-d '{"pao2":55,"paco2":32,"fio2":"0.21","age":60,"patm":0,"decimalPlaces":1}'API reference
Send a POST request with your inputs as JSON. File parameters require a separate upload first.
Endpoint
POST https://api.elysiatools.com/en/api/tools/a-a-gradient-calculatorParameters
| Name | Type | Required | Description |
|---|---|---|---|
| pao2 | number | Yes | Arterial partial pressure of oxygen (mmHg) from ABG. |
| paco2 | number | Yes | Arterial partial pressure of CO₂ (mmHg) from ABG. |
| fio2 | select | Yes | — |
| age | number | Yes | Patient age (years), used for age-adjusted normal A-a gradient. |
| patm | number | No | Atmospheric pressure (mmHg). Default 760 at sea level. Lower at altitude (e.g. Denver ~630). |
MCP integration
Add this tool to your Model Context Protocol server so AI agents can list and call it.
Server configuration
Add this block to your MCP client configuration:
{
"mcpServers": {
"elysiatools-a-a-gradient-calculator": {
"name": "a-a-gradient-calculator",
"description": "Calculate the alveolar-arterial O₂ gradient to distinguish hypoxemia causes. PAO₂ = FiO₂×(P_atm−47) − PaCO₂/0.8; A-a = PAO₂ − PaO₂. Normal ≈ (Age+10)/4. Elevated → V/Q mismatch, shunt, diffusion impairment. Derived from StatPearls, LITFL, Cornell PICU, and Martin 1999. Not medical advice.",
"baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=a-a-gradient-calculator",
"command": "",
"args": [],
"env": {},
"isActive": true,
"type": "sse"
}
}
}List available tools
After connecting to the SSE endpoint, list the exposed tools:
{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/list"
}Call this tool
Invoke the tool by its id, passing arguments built from its parameters:
{
"jsonrpc": "2.0",
"id": 2,
"method": "tools/call",
"params": {
"name": "a-a-gradient-calculator",
"arguments": {
"pao2": 55,
"paco2": 32,
"fio2": "0.21",
"age": 60,
"patm": 0,
"decimalPlaces": 1
}
}
}Questions or issues? Contact [email protected]