Epic, Omnissa Horizon, IGEL OS, and ScrewDrivers® were never sold as a bundle. Yet the hospitals that stay online through ransomware, hardware failures, and Patch Tuesday keep converging on the same four-layer architecture. Here's why — and what it looks like when the last layer is done right.
The Resilient Clinical Stack is a four-layer reference architecture for always-on clinical care: Epic as the system of record, Omnissa Horizon as the delivery layer, IGEL OS at the endpoint, and Tricerat ScrewDrivers® as the output layer. Each layer is engineered around one design principle: no single failure should ever reach the patient.
Most health systems already run two or three of these layers. This post breaks down what each one does, why the combination keeps showing up in the best-run Epic environments, and why the fourth layer — output — is the one most hospitals miss.
At 6:58 a.m., a nurse taps her badge at a workstation outside Room 412. Her Epic session — the one she left on the third floor — appears in seconds, open to the same patient. A wristband prints at the bedside. Nothing about that moment looks impressive, which is exactly the point: every layer of technology underneath it worked, in order, without being noticed.
That invisibility is getting harder to deliver:
The uncomfortable truth behind those numbers is rarely a missing product. Most hospitals already own excellent technology. What they lack is architecture: the layers were bought at different times, by different teams, for different reasons — assembled by accident rather than engineered as a stack. And a stack assembled by accident fails by accident: a spooler crash on a print server, an unpatched Windows endpoint, a session that dies when a clinician changes floors.
The Resilient Clinical Stack is the deliberate version — a quiet consensus that has been forming among high-performing health systems:
|
Layer |
Solution |
What it does |
|
01 · Record |
Epic |
The system of record for 43.7% of U.S. acute-care hospitals |
|
02 · Delivery |
Omnissa Horizon |
Sessions live in the data center — patched once, delivered everywhere, roaming with the clinician |
|
03 · Endpoint |
IGEL OS |
Read-only Linux OS, no local PHI, up to 95% smaller attack surface |
|
04 · Output |
ScrewDrivers® |
Driverless printing, native IGEL OS app, HA failover in under 30 seconds, secure release |
Four products, four vendors — one design principle: no single failure should ever reach the patient.
Epic now holds the chart for 43.7% of U.S. acute-care hospitals and nearly 57% of hospital beds. But an EHR is only as available as the infrastructure that delivers it. Installing Epic on thousands of individual clinical workstations means thousands of individual points of patch drift, local data exposure, and failure.
The stakes are not subtle: an hour of EHR downtime is estimated at $1.7 million to $3.2 million for a mid-sized to large hospital. The systems that treat Epic availability as a clinical requirement — not an IT metric — almost never run it on distributed fat clients.
That's where Omnissa Horizon comes in. Horizon delivers Epic from the data center or cloud as a virtual desktop or published app: patch it once, and every user on any approved device gets the latest version instantly. The clinician's session doesn't live on the device in front of them — it lives in the data center, which means it can follow them from the ED to the fourth floor and pick up exactly where it left off.
The engineering under that experience is specific to healthcare's realities:
And when a device fails, the session doesn't. Swapping hardware becomes a five-minute fix instead of a workflow outage.
If the session lives in the data center, the endpoint no longer needs to be a full Windows PC — and shouldn't be. IGEL OS is a read-only, Linux-based operating system purpose-built for secure access. Nothing is stored locally, so a stolen workstation-on-wheels holds no PHI, and there is nothing writable for ransomware to encrypt.
IGEL estimates its preventive security model reduces the endpoint attack surface by as much as 95% — and endpoint TCO by up to 75% — compared with managing full Windows devices. IGEL OS also integrates natively with Horizon: the two are engineered, tested, and marketed as a pair for clinical environments.
Ask a CIO to diagram their clinical stack and they'll draw the first three layers from memory. The fourth — output — is where the diagram usually goes quiet. Yet almost every clinical workflow ends in something physical: a patient wristband, a medication label, a lab requisition, discharge paperwork. When those stop printing, care stops moving — regardless of how resilient the layers above are.
Print earns its place in the architecture twice over:
This is the gap ScrewDrivers® was built to close. Tricerat makes enterprise print driverless — no OEM drivers to install on golden images, endpoints, or session hosts, and nothing driver-shaped left to patch. Patented compression cuts print traffic by as much as 10×, hardened high-availability print servers fail over in under 30 seconds, and secure release holds sensitive jobs until the right person authenticates at the device — AES-256 in transit, HIPAA-ready audit logs.
Nor is it bolted on from the outside. Tricerat has been a Technology Alliance Partner in the VMware-to-Omnissa ecosystem since 2007, and ScrewDrivers® ships as a native IGEL OS app in the IGEL Ready catalog — so where the workflow calls for it, an IGEL endpoint prints natively through ScrewDrivers® inside the Horizon session, with no Windows spooler in the path. Delivery, endpoint, and output aren't three vendors tolerating each other; they're validated pieces of the same architecture.
What makes this stack more than a convenient pairing is that its vendors are now engineering for failure together. In March 2026, IGEL and Omnissa announced an expanded healthcare partnership centered on an Isolated Recovery Environment — an approach that keeps clinicians working with a full client experience, not a stripped-down browser session, even while primary systems are down during a cyber incident.
That is the direction of travel for the whole architecture: assume the attack, assume the outage, and design each layer to degrade gracefully while the others hold. The record stays consistent because it never left the data center. The session survives because it isn't tied to a device. The endpoint can't be encrypted by ransomware because it's read-only. And the wristband still prints because the print path has no single point of failure.
That principle runs through the whole stack, but it lands hardest at the output layer. Going driverless doesn't just shrink what attackers can reach — the same consolidation of OEM drivers, GPOs, and standalone print servers rewrites the operating model behind print. Fewer moving parts to patch, fewer tickets to work, fewer admin hours to burn: the security win and the operational win are the same move, not a trade-off.
Most health systems reading this already run two or three of these layers. The difference between owning the products and owning the outcome is the discipline of treating them as one stack — including the layer everyone forgets.
The Resilient Clinical Stack is a four-layer reference architecture for always-on clinical care: Epic (system of record), Omnissa Horizon (delivery), IGEL OS (endpoint), and Tricerat ScrewDrivers® (output). Each layer is designed to degrade gracefully so that no single failure — ransomware, hardware loss, or a crashed print spooler — ever reaches the patient.
No. ScrewDrivers® completes the stack rather than replacing any layer of it. It adds driverless, high-availability printing to the Epic-over-Horizon-on-IGEL architecture most health systems already run, with no rip-and-replace required.
Yes. ScrewDrivers® ships as a native IGEL OS app in the IGEL Ready catalog, so an IGEL endpoint can print through ScrewDrivers® inside the Horizon session with no Windows spooler in the path.
Most Epic print failures trace to the traditional Windows print path: OEM driver conflicts on session hosts, Windows Print Spooler crashes, and single print servers with no failover. A driverless print layer with high-availability failover removes those single points of failure. See our breakdown of common Epic printing issues.
Industry research estimates an hour of EHR downtime costs a mid-sized to large hospital between $1.7 million and $3.2 million — before accounting for clinical impact. Peer-reviewed research from 2026 found in-hospital mortality rose 34–38% among patients already admitted when a ransomware attack began.
ScrewDrivers® doesn't replace Epic, Omnissa Horizon, or IGEL — it completes them. Tricerat's engineers will map the Resilient Clinical Stack against your environment. No rip-and-replace required.
