```python
from fastapi import FastAPI, status
from fastapi import Request
from fastapi.responses import JSONResponse
from pydantic import BaseModel
import helpers
import asyncio

app = FastAPI()

class Document(BaseModel):
    name: str
    text: str

@app.post("/documents", status_code=status.HTTP_201_CREATED)
async def save_document_endpoint(doc: Document):
    loop = asyncio.get_running_loop()
    # Run the blocking I/O in a thread pool to avoid blocking the event loop
    bytes_saved = await loop.run_in_executor(
        None, helpers.save_document, doc.name, doc.text
    )
    return {"bytes": bytes_saved}
```