Changes in R-Wave amplitude in DII lead is less sensitive than pulse pressure variation to detect changes in stroke volume after fluid challenge in ICU patients postoperatively to cardiac surgery

The amplitude of R-wave in DII lead (RDII) has been shown to correlate to central blood volume in animal and healthy volunteers. The aim of this study was to assess if change in RDII (DeltaRDII) after passive leg rise (PLR) and fluid loading would allow detecting preload dependence in intensive care ventilated patients. This parameter was compared to concomitant changes in pulse arterial pressure (DeltaPP).

Observational study in 40 stable sedated and ventilated cardiac surgery patients studied postoperatively. In line with our routine practice we performed a 45 degrees passive leg rise (PLR1) to detect preload dependence. If cardiac index or DeltaPP rose more than 12 and 13%, respectively, the patient was declared as non-responder (NR) to fluid loading. If these criteria were not met, they were declared as responders (R) and received a 500 ml of gelatin fluid loading (FL) followed by a second passive leg rise (PLR2). Hemodynamic parameters were assessed during each maneuver using their indwelling Swan-Ganz and radial catheter.

We identified 16 R and 24 NR whose hemodynamic parameters did not differ at basal condition, except DeltaPP (19% +/- 7 in R vs. 7% +/- 4 in NR, P < 0.001). PLR1 did not elicit any hemodynamic change in NR. In R, DeltaPP decreased and SV rose, both significantly (P < 0.001) whereas DeltaRDII did not vary. FL induced a more pronounced change in these parameters.

DeltaRDII in response to PLR does not successfully help identifying preload dependent patients contrarily to DeltaPP or change in stroke volume.