The R Series platform: assemblies, options, OneStep accessories, power and Code Readiness

Identify which R Series model and options are in front of you, name the assembly behind each function from the selector switch to the capacitor, and explain what the Code Readiness system actually tests and what it leaves to you.

One family, several front panels

The R Series is a hospital defibrillator family built on one internal platform. The same housing, battery, printer and therapy core are used across the range, and the models differ mainly in front panel, software features and fitted options. You will meet three names on the label. The R Series ALS is the manual defibrillator with an advisory mode, the one a resuscitation team uses for manual shocks, synchronised cardioversion and, if fitted, pacing and the monitoring options. The R Series Plus and the R Series BLS start in AED mode and can be switched to manual operation by trained staff; the Plus carries features that the BLS lacks; in the guide revision we used these include See-Thru CPR filtering and USB and Wi-Fi data transfer. The exact split depends on model and software version, so check the feature table in the operator's guide for the unit in front of you. Your service documentation is one service manual for the whole family plus separate operator's guides for ALS and for BLS/Plus, and a configuration guide.

OneStep is not a model. It is ZOLL's name for the therapy cable and electrode family that connects to the large multifunction connector on the right side of the unit. Hands-free electrodes, external paddles and internal paddles all plug into that one cable, and the cable is the path for shocks, pacing, pad ECG, impedance and, with the right electrodes, CPR sensing and electrode identification. Treat the OneStep cable as a part of the therapy circuit, not as an accessory: many faults reported as 'defibrillator failure' end there.

In Level 1 and Level 2 you learned how a biphasic defibrillator charges, stores and delivers energy and how to test it. This course does not repeat that. It tells you how this particular platform is divided, what each assembly does, which messages point at which assembly, and which checks the manufacturer expects before the unit goes back to a ward.

What to record before you touch anything

Start every job by identifying the configuration, because spare parts and expected test results depend on it. Record the model, the serial number, the software version shown at start-up or on the configuration report, and which options are fitted. The options that change the inside of the unit are pacing, pulse oximetry (with a Masimo or a Nellcor module, which use different sensors and different internal assemblies), mainstream EtCO2, non-invasive blood pressure and, where fitted, the Wi-Fi data card. Note also whether the unit is configured for remote sync from a patient monitor. Note also whether the unit uses paddles or is configured for hands-free electrodes only, and which ECG cables the ward uses.

The replacement parts list is organised by configuration. The system brick, the digital board kit, the parameter assembly and the display panel each exist in several versions for different option sets, and a part that looks identical may be the wrong one. Ordering by model name alone is a common way to receive a board that does not fit the unit's options.

Finally, ask about data before you start. The unit holds event records of real patients and a readiness log. Some of the annual tests create and erase report data, so the ward or the resuscitation lead must confirm that any record they need has been printed or transferred. This is covered in lessons 3 and 5.

Inside the housing: the system brick and its boards

Most of the electronics live in one block that the manual calls the system brick. It is removed as a unit and contains three main boards stacked together, plus the parameter assembly on units with options.

The digital system board is the main controller. It runs the user interface and the display, drives the strip-chart printer, keeps the real-time clock with its own lithium coin cell, stores data in non-removable flash memory, provides the USB and CompactFlash interfaces used for data transfer and software loading, and contains the watchdog and reset logic. When the manual tells you a task stopped responding or a memory check failed, it usually points here.

The analog system board has two roles. One part is the isolated core ECG: separate front ends for ECG taken through pads or paddles, including the measurement of patient impedance, and for the monitoring and diagnostic ECG leads. This front end recognises which ECG cable is connected and configures itself. The other part is non-isolated: the internal power supplies, battery and power monitoring, the measurement of the CPR sensor, the identification of electrodes and older accessories, and the path for the sync input and analog ECG output.

The pace/defib engine, the PD engine, is an independent module with its own processor, mounted with the high-voltage capacitor. It takes high-current power from the battery bus and commands from the digital board and generates both the rectilinear biphasic shock and the constant-current pacing pulse. The sync signal reaches it by a direct line rather than through software messages, so that the shock follows the R-wave with little delay. The PD engine and capacitor are supplied as one assembly. From a service point of view this is the block that holds lethal energy, and it is never opened outside the manufacturer's procedure.

Around the brick sit the front panel with its controls board, display and readiness indicator; the AC charger; the battery well with its interconnect board; the printer with its interconnect; the connector panel with the ECG input connector and the sync/ECG-out connector; the defibrillator test port on the side; and, on optioned units, the parameter power supply with the SpO2 module, the EtCO2 sensor interface and the NIBP module with its pump and pneumatics.

Power: AC charger, SurePower battery and what the unit knows about it

The unit runs from mains or from one SurePower lithium-ion battery pack. The internal AC charger converts mains to DC, charges the pack and supports operation; there is no way to run the unit sensibly without a battery, and the operator's guide says plainly not to try. The front panel shows an AC indicator and a battery indicator. A battery indicator that alternates between its two colours means either no battery or a charging fault, which is the first thing to look at when a ward reports a battery problem.

SurePower packs are not dumb cells. Each pack contains electronics that protect the cells, measure the state of charge, communicate with the host over a data bus and keep a usage history. The unit decides when to warn low battery and when to demand replacement from what the pack reports and from its own voltage measurements, and the PD engine adjusts how hard it draws current from the pack to avoid a shutdown while charging the capacitor. A pack that cannot communicate, a pack with an identification fault and a pack that draws abnormal charge current each produce their own message. The capacity of a pack is tested in the separate SurePower charger station, not in the defibrillator itself.

The consequence for you is that a 'battery fault' can be the pack, the charger, the battery interconnect board or the contacts in the well, and you separate them with a known-good pack and the charger station rather than with a multimeter on the terminals.

Code Readiness: what the green check proves

At the upper right of the front panel is the Code Readiness indicator: a green check means the most recent readiness test passed, a red X means it failed or has not been done. The unit runs this test at power-on, during operation, when an operator starts a manual test, and automatically once a day at a configured time if set up to do so. Results are kept in the readiness log, which holds a large number of entries and can be printed or exported.

The automatic test looks at the battery state of charge, the presence and expiry of the electrodes that can report it, the ECG acquisition electronics, the processor and software integrity, the CPR sensor circuit where relevant, and the charge and discharge of the defibrillator at a low test energy. That last part needs a closed path for the test discharge: the OneStep cable must be plugged into the test port, connected to adult paddles seated in their wells, or connected to an unopened package of OneStep electrodes, which act as a test load until opened. If the unit is unplugged from mains when the test fails, only the red X shows; on mains it also displays a report saying which function or accessory failed.

Two limits matter. First, the test discharge is internal to the unit's own measuring scheme. It shows that the circuit can charge and dump a small energy into the test path; it does not measure delivered energy at clinical levels into a realistic load, sync timing or pacing current. That is your job with an analyser. Second, a red X does not lock the unit. The device will still let a user try to shock, for example with expired pads connected. A red X is a reason to take the unit out of service and find out why, not something the device enforces.

Never try to make the indicator green by any route other than fixing the cause and passing the test. A readiness system that has been fooled is worse than none, because the ward trusts it.

On-site checklist

• Model (ALS, Plus or BLS), serial number and software version recorded
• Options recorded: pacing, SpO2 (Masimo or Nellcor), EtCO2, NIBP, Wi-Fi card if fitted, remote sync if configured
• Paddles or hands-free only; ECG cable types in use
• Readiness indicator state and last entries of the readiness log noted
• Battery packs: part numbers and condition; spare pack present
• Ward confirmed that any needed event records were printed or transferred

Check yourself