hi, i'm Mr. Dave!

A small API project

Scratch your own itch #

Every day I calculate anesthetic doses for dogs and cats. More precisely, every day I enter a few pieces of patient data into a spreadsheet and let Excel suggest anesthetic doses for dogs and cats. There will always be an element of human judgment involved, but calculating the baseline doses is much easier for a computer than it is for me at . The spreadsheet I made calculates typical doses for every anesthetic and emergency drug that we have available. It's fine, but I think I can do better.

Getting the data #

The FDA has a set of API for getting data about drugs. Most of the anesthetics we use in veterinary medicine are labeled for human use, so they are available via the openFDA NDC API. NDC for veterinary-only products aren't available via the API, so I'll provide a means to enter the data manually if it isn't already available. In the future, I would like to offer search by additional fields, like active ingredient or trade name, but the FDA API provides the quickest path to a working prototype.

For each drug saved, I will have to provide a list of doses that are typically used in my facility. This can be provided at any time, but storing it in advance will allow the output to have sane defaults. The anesthetic plan builder will also provide a means to override and provide arbitrary dosing while offering a warning if the entered dose is outside of the expected range.

flowchart TB
  Start-->methodPick
  methodPick[[Entry Method Picker]]
  methodPick--Enter drug details manually-->manualEntry
  manualEntry[[Manual Entry Form]]
  methodPick--Look up drug by code-->APILookup
  APILookup[[Drug Search Form]]
  APILookup-->APIFetch
  APIFetch((Data Fetch\nSubgraph))
  APIFetch--Success-->drugValidate
  APIFetch--Failure-->APILookup
  manualEntry-->drugValidate
  drugValidate[[Drug Data Validator]]
  drugValidate--Valid-->saveData
  drugValidate--Invalid-->methodPick
  saveData[[Save Drug to Pharmacy]]--more-->methodPick
  saveData--"that's plenty"-->done(((done)))

Keeping the data #

I don't want to implement backend authentication and storage for this project, so I'll rely on localStorage to hold drug data during the process and between sessions. I will need a way to restore data, possibly by providing a downloadable serialization of the user data or by a magic bookmark. The data needs to be persistent; I don't want to re-enter all my pharmacy data every time I have a new patient.

This is all part of the Save Drug to Pharmacy state from the chart above.

Using the data #

After the data for each drug in the pharmacy is saved, I need to build the anesthetic plan. The only piece of patient data that the computer needs is the patient's weight. Everything else I'll ask for is for reference and record-keeping. The interface will allow the selection of any of the stored drugs, calculate the weight-based dose, and present a summary of the plan in a printable format.

First, select which drugs to use from the previously saved information.

Sample Drug Selection #

Available Drugs Selected Drugs
midazolam 5 mg/mL hydromorphone 2 mg/mL
butorphanol 10 mg/mL <- dexmedetomidine 0.5 mg/mL
ketamine 100 mg/mL propofol 10 mg/mL
alfaxalone 10 mg/mL -> carprofen 50 mg/mL
meloxicam 10 mg/mL maropitant 10 mg/mL

These are list boxes, and the arrows are buttons, but I'm doing this in markdown so bear with me.

Then enter patient data and receive calculated dosing for the selected drugs, an IV fluid rate, and other nifty things. I've provided space for recording information required for the medical record. This tool can be used to calculate a plan or generate a baseline that a qualified individual can tweak to the individual patient's needs. Here the name, breed, and weight are reactive form fields, and admin time and by are for use on the printed document.

Sample Patient Data #

"Fluffy" Jones, Davey

Drug (name & strength) Dose quantity Dose volume Admin Time Admin By
maropitant 10 mg/mL 30 mg 3 mL ___:___
hydromorphone 2 mg/mL 6 mg 3 mL ___:___
dexmedetomidine 0.5 mg/mL 0.075 mg 0.15 mL ___:___
carprofen 50 mg/mL 120 mg 2.4 mL ___:___
propofol 10 mg/mL 180 mg 18 mL ___:___

The project is already started on GitHub at http://hiimmrdave.github.io/dosing. I'll write more about my planning and implementation as I work through it.