The PulSentry blog
Evidence-led writing on cardiac tamponade, pulsus paradoxus, and what a pulse oximeter waveform can reveal, for clinicians, and for anyone trying to understand the science.
What is pulsus paradoxus? A clinician's guide
The definition, how it is measured, the conditions it accompanies, when it is absent, and how the same signal appears on the pulse oximeter waveform.
Read → Clinical explainerWhy echocardiography misses post-surgical tamponade
After cardiac surgery, transthoracic echo is far less sensitive than many expect. What the evidence shows, and why the post-discharge window is a blind spot.
Read → ReimbursementThe 2026 Medicare RPM CPT code guide
99453, 99454, 99457, 99458, 99091, and the new 99445, what each pays, the day-count thresholds, and how short post-discharge monitoring fits.
Read → Clinical evidenceWhy TTE misses post-surgical pericardial hematoma
The 33% hematoma-sensitivity finding, scoped carefully, why loculated posterior collections defeat echo, and the case for waveform monitoring.
Read → Research-stageBeyond tamponade: the respiratory signal in the pulse-oximeter waveform
A scoped, honestly-hedged look at respiratory variation in the PPG across asthma severity, fluid responsiveness, and a research direction in breathlessness.
Read → TechnologyFFT and power spectral density of the PPG waveform, explained
How a pulse-oximeter signal is transformed into the frequency domain, and what the pulsus index measures.
Read → PrimerPulse oximetry 101: what the number and the waveform mean
What SpO2 actually measures, what the PPG waveform shows beyond it, common pitfalls, and why the waveform is underused.
Read → Clinical explainerCardiac tamponade after cardiac surgery: incidence, timing, detection
How often it happens, when it presents, which patients are most at risk, and why detection is harder than it sounds.
Read → ExpansionTamponade after Watchman, ablation, and transseptal procedures
Iatrogenic tamponade risk in structural-heart and electrophysiology procedures, and the monitoring window that matters.
Read → TechnologySoftware as a medical device: the regulatory pathway for a PPG algorithm
How a pulse-oximeter waveform algorithm is classified as software as a medical device, the 510(k) versus De Novo question, and what a predicate path looks like.
Read → ReimbursementThe post-discharge monitoring gap after cardiac surgery
Patients leave the hospital closely monitored, then go dark for weeks. The post-discharge blind spot, and the economics of closing it with remote monitoring.
Read → Clinical explainerWho is most at risk: tamponade after valve surgery and on anticoagulation
Late tamponade is more common after valve surgery and higher on anticoagulation. The highest-risk cardiac-surgery cohorts, and why they matter for monitoring.
Read → Clinical explainerFrom cuff to spectrum: the pulsus index vs bedside pulsus paradoxus
How the spectral pulsus index relates to the classic cuff-measured pulsus paradoxus, what each captures, and why a continuous signal matters.
Read → Clinical explainerThe history of pulsus paradoxus: from Kussmaul to a continuous signal
Adolf Kussmaul named the sign in 1873. Why the bedside cuff-and-ear method stayed stable for 150 years, and what a continuous reading of the same signal adds.
Read → ReimbursementThe cost of late tamponade detection: a health-economics view
Late tamponade forces an emergency pathway: unplanned readmission, urgent imaging, drainage or reoperation, and ICU escalation. Where that avoidable cost sits, and what earlier detection would have to achieve.
Read → Clinical explainerPericardial effusion vs tamponade: when an effusion turns dangerous
Not every pericardial effusion is tamponade. What separates a stable effusion from a hemodynamic emergency, why the speed of accumulation matters more than the volume, and why that window is easy to miss after discharge.
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