Addendum to below Tables on Aortic Dissection, Chamber Thrombus and Vegetations

Aortic Dissection 

There isn’t a single “fixed” test-characteristic for transthoracic echocardiography (TTE) in aortic dissection—the numbers depend on (1) whether the dissection involves the ascending (Stanford A) or descending (Stanford B) aorta, and (2) how the study defined a “positive” scan (intimal-flap only vs any suggestive sign)

How to interpret these numbers

• High specificity, limited sensitivity. A clearly visualised intimal flap on TTE is highly confirmatory; a negative study—especially when only parasternal/apical windows are obtained—cannot reliably exclude dissection, particularly type B disease.

• Ascending aorta is easier to see. Sensitivity is appreciably better for type A dissections because the proximal aorta and aortic root lie within normal TTE windows. Descending thoracic aorta is often obscured by lung and rib, leading to the much lower sensitivity for type B.

• Technique matters. Adding suprasternal notch views, harmonic imaging, or ultrasound contrast agents, and scanning specifically for any suggestive finding (intimal flap, root dilation, new AR, pericardial effusion) can push sensitivity above 90 %, while preserving high specificity.

• Clinical takeaway. Use TTE as a rapid bedside screen—particularly in haemodynamically unstable patients—knowing that:

• Positive TTE → can expedite surgical/cardiovascular CT confirmation.

• Negative or equivocal TTE → does not rule out dissection; proceed to gated CT angiography or TEE if suspicion remains high.

Vegetations /SBE

Rule of thumb: a positive (clearly mobile) vegetation on TTE is very reliable, but a negative study—especially in prosthetic valves or when image quality is sub-optimal—never rules out infective endocarditis and should be followed by TEE if clinical suspicion is high.

Why the numbers vary

• Vegetation size matters

  • Only ~25 % of vegetations < 5 mm are seen, but ~70 % of those 6–10 mm are detected ccjm.org.

  • Larger, more mobile masses are almost always picked up.

• Image quality & technique

  • Harmonic imaging and contrast agents explain why the recent meta-analysis (61 % sensitivity) out-performs older series from the 1990s (≈45 %).

  • Adding off-axis windows (right parasternal, suprasternal notch) and 3-D sweeps can push sensitivity into the mid-70 % range in experienced labs.

• Valve type

  • Acoustic shadowing from prosthetic material hides small vegetations, so sensitivity drops to ~30–50 %.

  • Conversely, specificity stays high because artefacts that mimic vegetations are well recognised.

Practical take-aways for reporting & patient care

1. Use TTE first for haemodynamically stable patients—it is fast, non-invasive, and will confirm IE in roughly two-thirds of native-valve cases.

2. Escalate to TEE (or gated cardiac CT/PET-CT for prostheses) when:

   • TTE is negative/equivocal but Duke or ESC/ACC clinical likelihood remains high.

   • The patient has a prosthetic valve, intracardiac device leads, prior surgery, or poor acoustic windows.

3. Repeat imaging 3–7 days later if suspicion persists; early vegetations may enlarge and become visible.

4. Document limitations in every negative TTE report: comment on image quality and indicate that small or prosthetic-masked vegetations cannot be excluded.

Bottom line: expect TTE to spot about two-thirds of native-valve vegetations and only one-half (or fewer) of prosthetic-valve vegetations, while maintaining >90 % specificity—hence the need for reflex TEE when the diagnosis still matters.

Any Chamber Thrombus

How to use these numbers in practice

• High specificity across the board – when you see a discrete, echo-dense mass with independent mobility at the expected location, it is very likely a true thrombus and should prompt treatment or confirmatory imaging rather than further scepticism.

• Sensitivity is chamber-dependent:

  • LV thrombus is easiest because the apex is usually in the near field; nevertheless, up to 40 % are still missed without contrast or apical-wall-motion scoring.

  • LA/LAA thrombus is routinely missed on TTE; a negative study never rules it out when the appendage is clinically relevant (e.g., before cardioversion). Proceed to TEE or CT.

  • Right-sided thrombi are rarer and often located in recesses or on hardware. Modified apical/sub-costal views and a focused search improve yield but many series still report only half of RV or 1 in 3 RA thrombi being seen on TTE.

• Contrast & advanced techniques help: LV opacifying agents or harmonic imaging increase sensitivity by ~15 %. There is emerging experience with intracavity contrast for atrial clots, but it is not yet routine.

• Report responsibly: For atrial or right-heart chambers, avoid a blanket “no thrombus” statement unless image quality genuinely excludes it; instead describe the acoustic windows and say “No thrombus seen; small or appendage thrombus cannot be excluded.”

Bottom line:
TTE is a rule-in tool for intracardiac thrombus – a positive finding is trustworthy – but its rule-out value varies: good for LV, modest for LA/LAA, and poor for RA/RV. When missing a clot has therapeutic consequences, reflex to TEE, cardiac CT or CMR.

Sensitivity and Specificity of Various ECHO Findings

Transthoracic Echo (TTE) for Aortic Dissection

Population / Technique	Sensitivity	Specificity
Any dissection (mixed Stanford A + B)	≈ 62 %	≈ 88 %
Ascending (Stanford A)	≈ 85 %	≈ 85 %
Descending (Stanford B)	≈ 46 %	≈ 87 %
Contrast-enhanced TTE (proximal)	up to 93 %	up to 97 %

Practical take-away: TTE is specific but not fully sensitive. A clear intimal flap is confirmatory; a negative TTE—especially for type B—must be followed with gated CT or TEE if suspicion remains high.

TTE for Detecting Vegetations (Infective Endocarditis)

Valve / Setting	Sensitivity	Specificity
Native valves	≈ 60–70 %	≈ 90–95 %
Prosthetic valves	≈ 30–55 %	≈ 85–90 %

Key points:

• TTE reliably rules-in IE when a mobile mass is seen, but a negative scan—especially with prosthetic valves—does not exclude the disease.
• Vegetation size and image quality dominate performance; consider harmonic imaging or early TEE when clinical suspicion is high.

TTE Sensitivity / Specificity for Intracardiac Thrombus

Chamber	Sensitivity	Specificity	Notes
Left Ventricle (LV)	≈ 55–60 %	≈ 95–99 %	Contrast boosts sensitivity to ~64 %
Left Atrium / LAA	≈ 40–60 %	≈ 90–94 %	Poor appendage visualisation; use TEE
Right Atrium (RA)	≈ 30 %	≈ 100 %	Few false-positives but many misses
Right Ventricle (RV)	≈ 40–50 %	> 90 %	Non-standard views improve yield

Clinical pearls: LV thrombus is the most detectable on TTE; atrial and right-sided clots are frequently missed. A positive TTE finding across chambers is highly specific and should trigger therapy or confirmatory imaging; a negative study rarely rules out LA/LAA or right-heart thrombus when management decisions hinge on exclusion.

Anti-Emetic Tool Box

ICU Anti‑Emetic Toolbox

1. Dopamine‑2 Antagonists / Pro‑kinetics

Agent	Typical ICU Dose	Pearls & ICU Cautions
Metoclopramide	5–10 mg IV q6 h	Anti‑emetic & pro‑kinetic; risk of akathisia/dystonia; ↓dose if CrCl < 40 mL/min
Haloperidol	1–2 mg IV q4–6 h PRN	Useful when agitation co‑exists; monitor QTc
Droperidol	0.625–1.25 mg IV ×1 (may repeat ×1)	Rapid onset; torsades risk—use with continuous ECG
Prochlorperazine	5–10 mg IV q6 h	Potent; EPS common—consider diphenhydramine cover

2. 5‑HT₃ (Serotonin) Receptor Antagonists

Agent	Typical ICU Dose	Pearls & ICU Cautions
Ondansetron	4 mg IV q6 h PRN (up to 8 mg)	Minimal sedation; mild QT prolongation; limit dose in severe hepatic impairment
Granisetron	1 mg IV q12 h	Longer half‑life than ondansetron; option for refractory cases

3. Antihistamine / Anticholinergic

Agent	Typical ICU Dose	Pearls & ICU Cautions
Diphenhydramine	25–50 mg IV q6 h PRN	Helpful for vestibular or medication‑induced NV; sedation & anticholinergic delirium in elderly
Promethazine	12.5–25 mg IV q6 h (slow, diluted)	Potent; vesicant—use large IV line; hypotension and sedation common
Scopolamine patch	1 patch q72 h	Great for vestibular & opioid taper NV; mydriasis—avoid in narrow‑angle glaucoma

Practical ICU Tips

• Start with the likely mechanism: gastroparesis → metoclopramide; opioid withdrawal → haloperidol; vestibular → diphenhydramine.
• Watch the ECG: Many agents prolong QT; obtain baseline & 2–4 h post‑dose ECG when stacking risks.
• Use combination therapy (e.g., 5‑HT₃ + dexamethasone + haloperidol) for refractory cases.
• Adjust for organ dysfunction: reduce metoclopramide in renal failure; limit ondansetron in severe hepatic disease.
• Route matters: IV or transdermal if bowel not functioning; consider NG/OG formulations for long‑term ventilation.
• Re‑evaluate daily: Persistent NV may signal underlying pathology—treat the cause, not just the symptom.

4. Neurokinin‑1 (NK₁) Receptor Antagonists

Agent	Typical ICU Dose	Pearls & ICU Cautions
Fosaprepitant	150 mg IV ×1 (24 h coverage)	Synergistic with 5‑HT3 blockers & steroids; CYP interactions (warfarin, tacrolimus)

5. Corticosteroid

Agent	Typical ICU Dose	Pearls & ICU Cautions
Dexamethasone	4–8 mg IV ×1–2 day	Adjunct for peri‑op, ↑ICP, bowel‑wall edema; onset 2–4 h; monitor glucose/WBC

6. Atypical Antipsychotic

Agent	Typical ICU Dose	Pearls & ICU Cautions
Olanzapine	2.5–5 mg PO/ODT/NG q12–24 h	Refractory chemo‑induced & multifactorial NV; sedation & hypotension; monitor QT

7. Adjunct / Special‑Situation Agents

Situation	Useful Agent(s)	Rationale
Severe gastroparesis / ileus	Erythromycin 250 mg IV q6 h	Short‑term pro‑kinetic; tachyphylaxis in 48–72 h; QT risk
Migraine‑associated NV	IV prochlorperazine ± diphenhydramine	Targets dopaminergic pathway; add IV fluids & magnesium
Cannabinoid hyperemesis	Haloperidol or droperidol	Superior symptom control vs ondansetron in studies
Anxiety‑triggered NV	Lorazepam 0.5–1 mg IV q4 h PRN	Combine with primary anti‑emetic; avoid oversedation

Quick First‑Line Cheat Sheet

Scenario	Go‑to First Dose
Undifferentiated ICU NV	Ondansetron 4 mg IV
Gastroparesis / tube‑feed intolerance	Metoclopramide 10 mg IV
Post‑op NV resistant to ondansetron	Droperidol 0.625 mg IV
Opioid‑exposed, agitated	Haloperidol 1 mg IV
Refractory / high emetogenic chemo	Fosaprepitant 150 mg IV + Ondansetron 8 mg IV + Dexamethasone 8 mg IV

Cannabinoids as Anti‑Emetics

Cannabinoid agonists activate CB₁ receptors in the brainstem vomiting center and enteric plexus, dampening both nausea perception and the motor drive to vomit. They pre‑date modern 5‑HT₃/NK₁ regimens and remain a fallback when standard agents fail—particularly in highly emetogenic chemotherapy or stubborn, multifactorial nausea.

FDA‑Approved Products (United States)

Product (brand)	Formulation / Schedule	Usual Anti‑Emetic Dose*	Approved Indication†	Practical ICU / Bedside Notes
Dronabinol (Marinol®)	2.5 / 5 / 10 mg oral capsules Schedule III	5 mg/m2 PO 1–3 h before chemo; then q2‑4 h × 4–6 doses/day (max 15 mg/m2/day)	CINV after failure of conventional anti‑emetics; AIDS‑related anorexia	Swallow intact; onset 30–60 min—better for prophylaxis. Capsule can be opened for NG administration if needed.
Dronabinol (Syndros®)	5 mg/mL oral solution Schedule II	Same mg/m2 schedule as capsules (administer with calibrated oral syringe)	Same as Marinol®	Faster absorption; alcohol‑containing vehicle—caution with hepatic impairment or disulfiram use.
Nabilone (Cesamet®)	1 mg capsules Schedule II	1–2 mg PO BID; start 1–3 h before chemo, continue BID ≤ 48 h after last dose	CINV refractory to standard therapy	Longer half‑life than dronabinol; no renal adjustment; chiefly hepatic metabolism.

*Adult dosing—titrate to lowest effective dose to limit CNS effects.
†All require prior failure of first‑line anti‑emetics per FDA labeling.

Preparations Not FDA‑Approved for NV

• Nabiximols (Sativex®): 1:1 THC:CBD oromucosal spray approved in Canada/UK for MS spasticity; small trials suggest CINV benefit but not FDA‑approved.
• Whole‑plant medical cannabis: Inhaled or edible forms legal in some U.S. states; THC/CBD ratio and bioavailability vary—not advised in critical‑care settings.

Practical ICU Considerations

1. Reserve for refractory cases – Current NCCN/ASCO algorithms place cannabinoids after failure of 5‑HT₃ + dexamethasone ± NK₁ ± olanzapine.
2. Route limitations – All FDA‑approved products are oral; require functioning GI tract or enteral tube.
3. Adverse effects – Euphoria/dysphoria, sedation, tachycardia, orthostatic hypotension, potential delirium; start low, reassess frequently.
4. Drug interactions – CYP2C9/3A4 substrates; monitor when co‑administered with azoles, macrolides, ritonavir, warfarin, tacrolimus.
5. Legal & storage considerations – Controlled‑substance handling: Schedule II (Cesamet, Syndros) vs Schedule III (Marinol); observe unit storage policies.

Bottom line: Synthetic cannabinoid agents offer a legally sanctioned, evidence‑based fallback for chemotherapy‑related nausea unresponsive to modern first‑line regimens. In the ICU they remain third‑line tools because of psychoactive side‑effects and oral‑only administration, but can salvage otherwise intractable nausea when used judiciously.