# eRHC Calculator PRO — Hemodynamic Calculation Tool

> Hemodynamic Calculation Tool (iPhone/iPad app by Andreas Kuhl.)

- Source: https://appshunter.io/ios/app/erhc-calculator-pro/id6753905333 (this page in markdown: same URL + `.md`)
- Developer: [Andreas Kuhl](https://appshunter.io/developer/1845608873)
- Category: Utilities, Medical
- Price: Free
- Age rating: 4+
- Requires: iOS 16.6 · 4 MB
- Languages: English
- Released: 2025-10-13
- Data updated: 2026-05-19
- User reviews in markdown: https://appshunter.io/ios/app/erhc-calculator-pro/id6753905333/reviews.md

## What is eRHC Calculator PRO?

eRHC Calculator PRO is a hemodynamic calculator app for qualified healthcare professionals, used during right heart catheterization (RHC) procedures. Here's what it contains:

App Purpose
A clinical calculation and documentation tool for invasive hemodynamic measurements — specifically tied to the ALLAY-HF and ALLAY-HFrEF clinical studies.

Key Features
Patient data management — save/load/share patient records as JSON files, with patient ID, institution, weight/height (kg/lb, cm/in), DOB, and BSA calculation
Multi-stage calculator — timed hemodynamic measurements across stages (rest, exercise, etc.) with vitals, pressures, V-waves, CO via thermodilution or Fick method
Threshold system — configurable alert thresholds with rules (lower/upper bound, range, special PCWP rules)
Time synchronization — reference clock offset for procedure timing
Print/share results — formatted report output
Formula reference — all formulas listed (BSA, mPAP, PCWP, TPG, VO₂, CO, CI, PVR)
Formulas Implemented
BSA: Mosteller (general) and Du Bois (Fick-specific)
mPAP: (sPAP + 2×dPAP) / 3
PCWP from V-Wave: ((V-High − V-Low)/3) + V-Low
TPG: mPAP − PCWP
VO₂: Gender-specific regression equations (Dehmer et al.)
O₂ content: (Sat/100 × Hb × 1.36) + dissolved O₂
CO (Fick): VO₂ / (arteriovenous O₂ difference × 10)
CI: CO / BSA
PVR: (mPAP − PCWP) / CO (in Wood units)

Legal/Info
Developer: Andreas Kuhl, Germany
Fully offline — no data collection, no internet, all data stays on device
Medical disclaimer: intended as a calculation aid only, not for standalone clinical decisions
© 2025-2026 Andreas Kuhl

Clinical References
Citations link to PubMed/journals for Mosteller, Chemla, Rajagopalan, Simonneau, ESC/ERS 2022 PH Guidelines, Du Bois, Dehmer, Severinghaus, Fick, and others.


## Version history (last 5 releases)

### 1.6.1 — 2026-05-05

minor bug-fixes

### 1.6 — 2026-02-28

Rounding issues fixed. All calculations are accurate with one decimal position. 
in the Calculator the used Thresholds / Study-parameters are listed in the header.
Home view: Basic-Data Button renamed to Patient/Basic Data, as the process starts here :-)

### 1.5 — 2026-02-16

New Logo.
Access to Base Data now on main Screen.

### 1.4 — 2025-11-13

Here is a short summary of the most important recent changes:

Fick Calculation Overhaul: Replaced all VO₂ estimations (Dehmer, Bergstra) with new, complex regression formulas based on height, weight, age, and sex. The calculation for oxygen content now also includes a detailed formula for dissolved O₂.

Dual BSA Logic: The app now uses two different BSA formulas:
Mosteller: Used for general display and for calculating the Cardiac Index (CI) from Thermodilution.
Du Bois: Used only for calculating the Cardiac Index (CI) from a Fick CO.

Data Persistence (Save/Load/Share):
Implemented a system to save and load complete patient datasets (including all stages and thresholds) using the Patient Identifier.
The "Load Patient" list now allows for deleting patient files.
Added a "Share Patient" function (via context menu) to export the raw patient .json file using the native Share Sheet.

Calculation & Display Logic:
All BSA values (Mosteller and Du Bois) are now rounded to one decimal place before being used in any subsequent CI calculations.
The print layout (PrintView) was updated to a single-column view, with "Vitals" always appearing first for each stage.

Bug Fixes: Resolved critical compiler errors (like "Cannot find type..." and "Invalid redeclaration") by refactoring data models (StageData, ThresholdSet) into a new SharedDataModels.swift file to break circular dependencies.

### 1.3 — 2025-10-31

What's New

This update introduces several enhancements and new features based on user feedback:

Enhanced Data Entry:
Added input fields for SBP, DBP, HR, and SpO2 to each stage under a new "Vitals" section.
Introduced separate Heart Rate fields: one in 'Vitals' (general HR for the stage) and one specific to the Fick calculation ('HR Fick').
Base Data: Added unit selection (kg/lb, cm/in) for Weight and Height. BSA calculation now correctly handles selected units.
Base Data: Added a timestamp button for "Patient on Table".
Timestamps for RAP, PAS, and PCWP are now displayed inline next to the parameter label using "@ HH:mm" format.

Improved Stage Functionality:
Legs Up: Added a 5-minute countdown timer with Start/Pause/Reset controls.
Legs Up: Enabled the "Large V-Waves" option for this stage.
Legs Up: The "Derived" calculation section is now hidden for this stage.
Exercise: Completely redesigned the timer section:
Input for Watt load is now at the top.

Features an advanced timer display: shows a 90-second countdown (red text) upon starting, then switches to a total elapsed time count-up (green text).
Includes smaller Start, Stop, and "Up" buttons in a single row.
"Start" and "Stop" set timestamps used to calculate the duration automatically.
"Up" button restarts the 90-second red countdown phase while the total elapsed time continues.
Start and Stop timestamps are displayed below the buttons.
Reset is now a text link below the buttons.

Refined Calculations & Display:
Calculated pressures (mPAP, TPG, PCWP V-W) are now rounded to whole numbers.
PCWP input field is visually disabled (greyed out, no threshold color) when "Large V-Waves" is active.
The calculated "PCWP (V-W)" value now shows the threshold background color correctly.
The label for calculated Cardiac Output now dynamically shows "CO (T)" for Thermodilution or "CO (F)" for Fick.

Reporting Enhancements:
Added Weight (with unit), Height (with unit), and "Patient on Table" time to the "Patient Data" section.
Added a dedicated "Vitals" section (SBP, DBP, HR, SpO2) before "Pressures" for each stage in the report.
Added a new "Gradients" section at the end of the report showing calculated "PCWP – RAP" for Rest and Exercise stages.
Improved report layout with wider spacing between columns (Parameter, Value, Status) for better readability, optimized for A4 printing.
The threshold status symbol for the standard PCWP value is now hidden in the report if "Large V-Waves" were used for that stage.

New Reference Section:
Added a new "Used Formulas" page accessible from the home screen, displaying all calculations used in the app in plain text format.

We hope you find these updates helpful!

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-05-19.*