R40.4: Transient alteration of awareness

R40.4, transient alteration of awareness, is listed as a covered diagnosis in 6 Medicare billing and coding articles that apply to 32 HCPCS Level II codes, including Q9957 (Injection, perflutren lipid microspheres, per ml), Q9956 (Injection, octafluoropropane microspheres, per ml), Q9955 (Injection, perflexane lipid microspheres, per ml). The articles come from 4 Medicare contractors. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.

HCPCS Level II codes with R40.4 as a covered diagnosis

CodeDescriptionMedicare coverageDMEPOS fee 2026 (state range)Articles listing it
Q9957Injection, perflutren lipid microspheres, per mlCarrier judgment—3
Q9956Injection, octafluoropropane microspheres, per mlCarrier judgment—3
Q9955Injection, perflexane lipid microspheres, per mlCarrier judgment—3
J0461Injection, atropine sulfate, 0.01 mgSpecial coverage instructions apply—3
J0153Injection, adenosine, 1 mg (not to be used to report any adenosine phosphate compounds)Special coverage instructions apply—3
J1250Injection, dobutamine hydrochloride, per 250 mgSpecial coverage instructions apply—3
J0280Injection, aminophyllin, up to 250 mgSpecial coverage instructions apply—3
J1245Injection, dipyridamole, per 10 mgSpecial coverage instructions apply—3
A9700Supply of injectable contrast material for use in echocardiography, per studySpecial coverage instructions apply—3
J2785Injection, regadenoson, 0.1 mgCarrier judgment—2
C8921Transthoracic echocardiography with contrast, or without contrast followed by with contrast, for congenital cardiac anomalies; completeSpecial coverage instructions apply—2
C8922Transthoracic echocardiography with contrast, or without contrast followed by with contrast, for congenital cardiac anomalies; follow-up or limited studySpecial coverage instructions apply—2
C8923Transthoracic echocardiography with contrast, or without contrast followed by with contrast, real-time with image documentation (2d), includes m-mode recording, when performed, complete, without spectral or color doppler echocardiographySpecial coverage instructions apply—2
C8924Transthoracic echocardiography with contrast, or without contrast followed by with contrast, real-time with image documentation (2d), includes m-mode recording, when performed, follow-up or limited studySpecial coverage instructions apply—2
C8928Transthoracic echocardiography with contrast, or without contrast followed by with contrast, real-time with image documentation (2d), includes m-mode recording, when performed, during rest and cardiovascular stress test using treadmill, bicycle exercise and/or pharmacologically induced stress, with interpretation and reportSpecial coverage instructions apply—2
C8929Transthoracic echocardiography with contrast, or without contrast followed by with contrast, real-time with image documentation (2d), includes m-mode recording, when performed, complete, with spectral doppler echocardiography, and with color flow doppler echocardiographySpecial coverage instructions apply—2
C8930Transthoracic echocardiography, with contrast, or without contrast followed by with contrast, real-time with image documentation (2d), includes m-mode recording, when performed, during rest and cardiovascular stress test using treadmill, bicycle exercise and/or pharmacologically induced stress, with interpretation and report; including performance of continuous electrocardiographic monitoring, with physician supervisionSpecial coverage instructions apply—2
C8925Transesophageal echocardiography (tee) with contrast, or without contrast followed by with contrast, real time with image documentation (2d) (with or without m-mode recording); including probe placement, image acquisition, interpretation and reportSpecial coverage instructions apply—1
C8926Transesophageal echocardiography (tee) with contrast, or without contrast followed by with contrast, for congenital cardiac anomalies; including probe placement, image acquisition, interpretation and reportSpecial coverage instructions apply—1
C8927Transesophageal echocardiography (tee) with contrast, or without contrast followed by with contrast, for monitoring purposes, including probe placement, real time 2-dimensional image acquisition and interpretation leading to ongoing (continuous) assessment of (dynamically changing) cardiac pumping function and to therapeutic measures on an immediate time basisSpecial coverage instructions apply—1
J3490Unclassified drugsSpecial coverage instructions apply—1
C9399Unclassified drugs or biologicalsSpecial coverage instructions apply—1
G2187Patients with clinical indications for imaging of the head: head traumaCarrier judgment—1
G2188Patients with clinical indications for imaging of the head: new or change in headache above 50 years of ageCarrier judgment—1
G2189Patients with clinical indications for imaging of the head: abnormal neurologic examCarrier judgment—1

7 more codes are listed. See every code with payment by region in Caduvo.

Medicare policy articles listing R40.4

A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.

Other R40 diagnoses (Somnolence, stupor and coma)

Frequently asked questions

Does Medicare cover R40.4 (Transient alteration of awareness)?

Medicare covers items and services, not diagnoses. 6 Medicare billing and coding articles list R40.4 as a covered diagnosis for 32 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.

Which HCPCS codes can be billed with ICD-10 R40.4?

The Level II codes from the policies most specific to this diagnosis are Q9957 (Injection, perflutren lipid microspheres, per ml, 3 articles); Q9956 (Injection, octafluoropropane microspheres, per ml, 3 articles); Q9955 (Injection, perflexane lipid microspheres, per ml, 3 articles); J0461 (Injection, atropine sulfate, 0.01 mg, 3 articles); J0153 (Injection, adenosine, 1 mg (not to be used to report any…, 3 articles). Code choice depends on the item supplied; check each code's descriptor.

Which Medicare policy articles list R40.4?

A56505 (Billing and Coding: Transesophageal Echocardiography (TEE)); A57306 (Billing and Coding: Transthoracic Echocardiography (TTE)); A56781 (Billing and Coding: Transthoracic Echocardiography (TTE)), and 3 more articles.

What is ICD-10-CM code R40.4?

R40.4 is the ICD-10-CM code for transient alteration of awareness, in category R40 (Somnolence, stupor and coma), chapter 18: Symptoms, signs and abnormal findings.

Next steps

Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.

Chapter 18: Symptoms, signs and abnormal findings · All diagnoses · HCPCS lookup