Formulas and sources
Cardiac output and index
Fick CO = VO₂ / [13.4 × Hb × (SaO₂ − SvO₂)] · VO₂ = VO₂ index × BSA · CI = CO / BSA · SV = CO / HR
Hb in g/dL, saturations as fractions, 1.34 mL O₂ per g Hb. The default VO₂ index of 125 mL/min/m² is the usual bedside assumption; assumed values differ from measured VO₂ by more than 25 % in a substantial minority of patients, so measured VO₂ is preferable when available. BSA by Mosteller: √(height cm × weight kg / 3600). Conventional reference range for CI: 2.5–4.0 L/min/m².
Narang N, Gore MO, Snell PG, et al. Accuracy of estimating resting oxygen uptake and implications for hemodynamic assessment. Am J Cardiol 2012;109:594–598. DOI
Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317:1098. DOI
Resistances and gradients
PVR = (mPAP − PCWP) / CO (Wood units; × 80 for dyn·s·cm⁻⁵) · SVR = 80 × (MAP − RA) / CO · TPG = mPAP − PCWP · DPG = dPAP − PCWP
MAP = DBP + (SBP − DBP) / 3. When PA mean is left blank it is estimated as (systolic + 2 × diastolic) / 3 and marked as estimated. Conventional SVR reference range 800–1200 dyn·s·cm⁻⁵. TPG > 12 mmHg and DPG ≥ 7 mmHg were the older markers of a pre-capillary component; the 2022 definitions use PVR instead.
Pulmonary hypertension definitions (2022 ESC/ERS)
PH: mPAP > 20 · pre-capillary: PCWP ≤ 15 and PVR > 2 · isolated post-capillary: PCWP > 15 and PVR ≤ 2 · combined: PCWP > 15 and PVR > 2
mPAP > 20 mmHg with PCWP ≤ 15 mmHg and PVR ≤ 2 WU is left unclassified. PVR > 5 WU is the guideline's threshold for severe PH. Normal resting mPAP is 14 ± 3 mmHg, which is where the 20 mmHg upper limit comes from.
Humbert M, Kovacs G, Hoeper MM, et al. 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Heart J 2022;43:3618–3731. DOI
Kovacs G, Berghold A, Scheidl S, Olschewski H. Pulmonary arterial pressure during rest and exercise in healthy subjects: a systematic review. Eur Respir J 2009;34:888–894. DOI
Right ventricular indices
PAPi = (sPAP − dPAP) / RA · RA / PCWP
PAPi < 0.9 identified severe RV dysfunction in acute inferior MI; PAPi < 1.85 and RA/PCWP > 0.63 were associated with RV failure after LVAD implantation. These are the thresholds flagged here; they are context-specific rather than universal cut-offs.
Korabathina R, Heffernan KS, Paruchuri V, et al. The pulmonary artery pulsatility index identifies severe right ventricular dysfunction in acute inferior myocardial infarction. Catheter Cardiovasc Interv 2012;80:593–600. DOI
Morine KJ, Kiernan MS, Pham DT, Paruchuri V, Denofrio D, Kapur NK. Pulmonary artery pulsatility index is associated with right ventricular failure after left ventricular assist device surgery. J Card Fail 2016;22:110–116. DOI
Kormos RL, Teuteberg JJ, Pagani FD, et al. Right ventricular failure in patients with the HeartMate II continuous-flow left ventricular assist device: incidence, risk factors, and effect on outcomes. J Thorac Cardiovasc Surg 2010;139:1316–1324. DOI
Cardiac power output
CPO (W) = MAP × CO / 451
Normal resting CPO is about 1 W. In the SHOCK trial registry CPO was the strongest haemodynamic correlate of in-hospital mortality, with 0.53 W the best cut-off; 0.6 W is the threshold in common use and is the one flagged here.
Fincke R, Hochman JS, Lowe AM, et al. Cardiac power is the strongest hemodynamic correlate of mortality in cardiogenic shock: a report from the SHOCK trial registry. J Am Coll Cardiol 2004;44:340–348. DOI
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