| Pmcf hold | Pmcf arm | Pmcf analogue |
---|---|---|---|
CO = (Pmcf CVP)/RVR | Pa = Pv | Pmcf = axCVP + bxMAP + cxCO | |
Applicability to a broad patient population | − | ± | ± |
 | Restricted to fully sedated and mechanically ventilated patients | In theory applicable in all patients (sedated or awake) with an radial artery catheter | In theory applicable in all patients (sedated or awake) |
 | Restricted to patients without a contraindication for inspiratory holds (such as COPD with bullae) |  | Continuous and accurate CO, MAP and CVP measurements needed |
 | Continuous and accurate CO and CVP measurements needed |  | Not suitable in cardiac arrhythmia |
 | Not suitable in cardiac arrythmia |  |  |
Accuracy | + | + | − |
 | Values interchangeable with Pmcf arm | Values interchangeable with Pmcf hold | Values significantly lower than derived with Pmcf hold |
 | When sedated baroreflex probably of little influence | Dependent on time of measurement: > Pa and Pv equilibration. < hypoxia-induced vasodilatation | Pmcf analogue can be transformed to Pmcf hold values (constant error) |
 | Mechanical ventilation may overestimate Pmcf value | Possible influence rapid cuff inflator on reflex mechanism altering Pmcf value in non-sedated patients. This is not studied | Mathematical coupling and the equation is based on assumptions that may not be generalizable to all patient populations in ICU |
Precision | ? | + | ? |
 | Not studied | No significant differences during repeated measurements. LSC for a single measurement is 14% | Not studied |
Outcome operator independent | − | ± | + |
 | Inspiratory holds | Timing of measurement | CVP transducer position and CO measurement technique |
 | CVP transducer position and CO measurement technique |  |  |
 | Extrapolation of curve |  |  |
Responding time | − | + | + |
 | > 4 min | 30–60 s | Fast, no exact times mentioned |
Costs | − | + | + |
 | Theoretically no extra devices needed than standard present in ICU | Rapid Cuff Inflator (Hokanson E20, Bellevue, Washington, USA) = 3000 euro | Navigator™ (Applied Physiology, Pty Ltd, Sydney, Australia) |
 |  |  | Price unknown |
Risk of complications | + | ± | − |
 | No complications reported in published studies. In theory: | No complications reported in published studies. In theory: | No complications reported in published studies. In theory: |
 | Barotrauma from inspiratory holds | In sedated patients attention should be paid deflating the rapid cuff before hypoxemia-induced damage can occur | Complications associated with central venous catheters and CO measurement |
 | Severe hemodynamic instability induced by inspiratory holds | In awake patients local pain could be caused by inflating the rapid cuff inflator |  |
 | Complications associated with central venous catheters and CO measurement |  |  |