Types of Telehealth: Synchronous, Asynchronous, and Remote Monitoring

Telehealth is not a single technology or a single encounter — it is a family of delivery models that differ in timing, data type, and clinical workflow. Three categories form the foundation of that family: synchronous care (live video or audio), asynchronous care (store-and-forward communication), and remote patient monitoring (continuous or periodic physiological data collection). Understanding how these models differ, where they overlap, and what each one demands from patients and providers is essential for anyone navigating the modern healthcare system.

• Definition and scope
• Core mechanics or structure
• Causal relationships or drivers
• Classification boundaries
• Tradeoffs and tensions
• Common misconceptions
• How each model is typically deployed
• Reference table or matrix

Definition and scope

The Health Resources and Services Administration (HRSA) defines telehealth broadly as the use of electronic information and telecommunications technologies to support long-distance clinical health care, patient and professional health-related education, public health, and health administration. Within that umbrella, the three primary modalities each carry a distinct operational definition.

Synchronous telehealth refers to real-time, two-way communication between a patient and a provider — typically via video conferencing, but also by telephone. The encounter happens in the same moment, just not the same room. Medicare's coverage framework, outlined in 42 CFR §410.78, has historically treated synchronous video visits as the default telehealth interaction and the standard against which reimbursement eligibility is assessed.

Asynchronous telehealth, often called store-and-forward, involves collecting clinical information — images, video clips, documents, messages — and transmitting it to a provider for review at a later time. No live interaction occurs. The American Telemedicine Association (ATA) identifies dermatology, radiology, and ophthalmology as the specialties that have most thoroughly integrated this model, largely because their diagnostic workflows center on visual data that does not require a real-time exchange.

Remote patient monitoring (RPM) captures physiological data — blood glucose, blood pressure, oxygen saturation, cardiac rhythm, body weight — from a patient outside a clinical setting and transmits that data to a care team. RPM sits at the intersection of telehealth and medical device regulation, which gives it a more complex regulatory profile than the other two modalities. The telehealth types and modalities reference provides a broader catalog of the specific service categories within each model.

Core mechanics or structure

Each modality has a distinct technical and procedural architecture.

In a synchronous visit, two endpoints — patient and provider — connect in real time over an encrypted video or audio channel. HIPAA-compliant platforms must meet the Security Rule requirements under 45 CFR Part 164, including data encryption in transit and access controls. The clinical encounter follows a structure closely parallel to an in-person visit: the provider conducts a history, performs an observable physical assessment, and may prescribe or refer. Latency and image quality are operational constraints — a pixelated video feed matters little for a medication refill review, considerably more for a dermatological assessment of a rash.

In asynchronous (store-and-forward) telehealth, a referring provider or the patient captures clinical data using a structured intake form, secure messaging portal, or specialized application. That data packet — which might include a high-resolution photograph of a skin lesion, an audiogram, or a series of retinal images — is stored on a secure server and routed to a specialist who reviews it within a defined response window, often 24 to 72 hours. The reviewing specialist does not interact with the patient directly during that review. Store-and-forward telehealth details the specific technical requirements and specialty applications for this workflow.

In remote patient monitoring, FDA-regulated devices collect biometric data continuously or on a scheduled basis. That data is transmitted via cellular or Bluetooth connection to a platform where algorithms flag anomalies for clinical review. Under CPT codes 99453, 99454, 99457, and 99458 — as defined by the American Medical Association's CPT Editorial Panel and recognized in Medicare billing guidance from CMS — RPM services are billed separately from the underlying condition management and require documented patient consent and a minimum of 16 days of data per 30-day period for device supply reimbursement. Remote patient monitoring covers the device ecosystem and billing mechanics in full.

Causal relationships or drivers

The three-modality structure did not emerge from a single policy decision. It evolved from the technical constraints and clinical use cases that existed before broadband was widely available.

Store-and-forward developed first, in the 1990s, because transmitting a static image required far less bandwidth than a live video stream. Teledermatology and teleradiology became viable at connection speeds that would make a synchronous video call unwatchable. Synchronous video became the dominant policy and reimbursement model once broadband penetration made live video reliable enough for clinical use — a threshold that varied enormously by geography and that the telehealth broadband and connectivity resource addresses directly.

Remote monitoring's growth was driven by a different force: the proliferation of consumer-grade sensors capable of producing clinically meaningful data. A pulse oximeter that once cost several hundred dollars and lived only in a clinic now retails for under $30. That cost compression, combined with the chronic disease burden in the US population — where, according to the CDC, 6 in 10 adults have at least one chronic condition — created both the supply of affordable hardware and the demand for continuous rather than episodic monitoring.

Classification boundaries

The three modalities are conceptually distinct but clinically entangled. A single patient encounter can span all three within the same care episode.

A patient with hypertension might transmit 30 days of blood pressure readings via RPM (asynchronous, automated), send a secure message asking about medication side effects (asynchronous, human-initiated), and then join a scheduled video visit where the provider reviews the RPM trend data in real time (synchronous). Each of those touchpoints triggers different billing codes, different privacy requirements, and potentially different licensure rules depending on the state. Telehealth billing and coding maps the intersection of these modality types with reimbursement structures.

The regulatory boundary that matters most is the distinction CMS draws between RPM and chronic care management. RPM is device-mediated and requires FDA-cleared hardware. Chronic care management involves non-device-mediated communication and coordination. Conflating the two produces billing errors with real compliance consequences.

Tradeoffs and tensions

No modality is universally superior. Each carries genuine tradeoffs that affect patients and providers differently.

Synchronous telehealth offers immediacy and the closest analog to in-person clinical interaction, but it requires simultaneous availability from both parties, a stable internet connection, and a device with camera and microphone capability. For patients in areas where broadband penetration remains below 65% of households — a figure the FCC Broadband Deployment Report has documented in rural geographies — synchronous video may be technically inaccessible.

Asynchronous telehealth eliminates the scheduling barrier and allows specialist review without geographic constraints, but it introduces a response delay that is clinically acceptable for stable, non-urgent conditions and potentially dangerous for anything that deteriorates rapidly. A teledermatology photograph submitted on a Friday may not reach the reviewing dermatologist until Monday. For a mole that turns out to be a melanoma, that delay is medically tolerable. For a rash that is actually a drug reaction, it may not be.

Remote monitoring generates continuity of data that episodic visits cannot replicate, but it also generates noise. A patient whose blood pressure monitor is applied incorrectly will produce 30 days of systematically inaccurate readings that a clinical algorithm may flag as hypertensive urgency. Alert fatigue — where providers receive so many automated notifications that meaningful signals are missed — is a documented operational hazard in RPM programs, flagged in telehealth quality metrics research.

Common misconceptions

Misconception: Asynchronous telehealth is just email. Secure messaging through a HIPAA-compliant patient portal is one form of asynchronous communication, but store-and-forward telehealth is a structured clinical workflow involving standardized intake data, specialist-grade image capture, and documented provider review that generates a billable clinical note. It is not a patient emailing a photograph to a doctor's Gmail account.

Misconception: RPM is the same as wearable health tracking. A Fitbit records steps. An FDA-cleared blood pressure cuff enrolled in a Medicare RPM program generates reimbursable clinical data. The legal, technical, and clinical distinctions are substantial. Wearable health devices and telehealth draws the regulatory line precisely.

Misconception: Synchronous video is always required for a "real" telehealth visit. Medicare and most commercial payers recognize asynchronous encounters and RPM-related services as billable telehealth events. The misconception likely traces to the early policy framing of telehealth as video-first, which was accurate for reimbursement purposes for much of the 2000s but has since been revised substantially, particularly following the 2020 public health emergency expansions documented in telehealth post-pandemic policy changes.

Misconception: Any internet-connected health device qualifies for RPM billing. CMS requires that RPM devices be FDA-cleared medical devices. Consumer wellness devices, regardless of accuracy, do not meet this threshold for Medicare billing purposes.

How each model is typically deployed

The following sequence describes the standard operational steps across all three modality types — not as prescriptive advice, but as a descriptive map of how these workflows function in practice.

Synchronous visit — typical operational sequence:
1. Patient schedules appointment through a platform or patient portal
2. Provider verifies patient identity and confirms informed consent per state requirements
3. Both parties connect via encrypted video link at the scheduled time
4. Provider conducts history, observable assessment, and clinical decision-making
5. Encounter is documented in the EHR; prescriptions, referrals, or follow-up are issued
6. Billing submitted under appropriate telehealth CPT or HCPCS code with place-of-service modifier

Asynchronous (store-and-forward) — typical operational sequence:
1. Patient or referring provider completes structured intake and uploads clinical data (images, records, questionnaire)
2. Data is transmitted to secure server and routed to reviewing specialist
3. Specialist reviews case asynchronously, within agreed response window (commonly 24–72 hours)
4. Specialist generates a clinical note or consultation report
5. Report is transmitted back to referring provider and/or patient
6. Billing submitted under applicable telehealth consultation code

Remote patient monitoring — typical operational sequence:
1. Provider orders RPM service and patient provides written consent
2. FDA-cleared device is supplied to patient (clinically ordered or self-procured)
3. Device transmits readings over minimum 16 days per 30-day billing period (CMS requirement)
4. Platform flags outlier readings; clinical staff reviews alerts and contacts patient as indicated
5. Monthly interactive communication between patient and clinical staff (required for CPT 99457)
6. Billing submitted under RPM-specific CPT codes; documentation supports medical necessity

The National Telehealth Authority home resource maps how these modality types connect to the broader policy and coverage landscape.

Reference table or matrix

References

• Health Resources and Services Administration (HRSA) — Telehealth Programs
• Centers for Medicare & Medicaid Services (CMS) — Telehealth Services
• American Telemedicine Association (ATA)
• Code of Federal Regulations, 42 CFR §410.78 — Telehealth Services
• Code of Federal Regulations, 45 CFR Part 164 — HIPAA Security Rule
• CDC — Chronic Disease Data and Statistics
• FCC Broadband Deployment Report
• CMS Telehealth Codes Reference