2.3.1 Overview

High resolution waveforms were converted from a proprietary format into MIT's WFDB format (explained later in this chapter). Our waveform collection efforts were essentially broken into two groups, which reflect different versions of the Philips waveform archiving software. The first group includes approximately 2,800 records, each consisting of:

• Up to 4 simultaneous channels sampled at 125 Hz, with an amplitude resolution of 8 bits, normally containing 2 leads of ECG, ABP and a pulmonary artery pressure (PAP) if available. If the PAP was not available, a respiratory signal (impedance pneumogram) an oxygen saturation waveform (photoplethysmogram) was recorded.
• Up to 30 parameters recorded once a minute with an amplitude resolution of up to 16 bits . Parameters include heart rate (HR), systolic/mean/diastolic blood pressure (ABPSys/ABPMean/ABPDias), peripheral oxygen saturation (SpO2), and cardiac output (CO).
• All bedside monitor-generated alarms (such as arrhythmias) and in-ops (such as sensor disconnects).

Upgrades in hardware and software allowed us to improve data collection and gather a second group of records to include:

• Up to 8 simultaneous channels sampled at 125 Hz.
• Analog to digital resolution of 10 bits.
• Trend parameters with a temporal resolution of once a second.

This second, improved, data collection effort is ongoing, and will be added to the public database as we process them.