Table 3.
Biases and limits of agreement of the studies regarding the use of CVP swings as an estimate of esophageal or pleural pressure swings.
| Author, Year | Biases | Limits of Agreement |
|---|---|---|
| Walling and Savege, 1976 [31] | Small sample size, indirect conclusions, different measurement systems (fluid-filled and air-filled). | Pl swings measured from ΔPes were 30% higher than those measured from ΔCVP. Previous studies reported a similar higher ΔPes (26.4%) when compared with the direct measurement of ΔPpl, suggesting a comparable value of ΔPpl and ΔCVP. |
| Kyogoku et al., 2020 [32] | Small sample size, included only children, severe ARDS cases not included, most cases post cardiac surgery. | cΔCVP-derived ΔPpl correlated with ΔPes better than did ΔCVP (R2 = 0.48, p = 0.083 vs. R2 = 0.14, p = 0.407) |
| Okuda et al., 2021 [33] | Small sample size, included only children, impact of cardiogenic oscillations on ΔCVP and ΔPes measurements. | Difference of cΔCVP-derived ΔPpl to ΔPes was smaller than that of ΔCVP to ΔPes at all support levels (−0.1 ± 1.5 vs. 3.1 ± 3.5 cmH2O in PS 10, −0.7 ± 3.3 vs. 4.5 ± 3.9 cmH2O in PS 5, and −1.0 ± 3.4 vs. 4.7 ± 4.4 cmH2O in PS 0) |
| Verscheure et al., 2017 [34] | Effect of gravity and frequency response of fluid-filled catheters, ventilator-triggered breaths during controlled ventilation. | Comparing ΔPes and ΔCVP, the bias was close to 0 mmHg in CMV and −2 mmHg in PSV. |
| Flemale et al., 1988 [35] | Small sample size, cardiac artifacts with fluid-filled esophageal catheters, hydrostatic pressure gradient between catheter tip and pressure transducer modified by respiratory movements. | ΔCVP/ΔPm, ΔPes/ΔPm and ΔPes/ΔCVP individual values and group average were close to unity in all positions. |
| Aguilera et al., 2018 [36] | Small sample size, measurements limited to cough, no ventilation. | Average maximum pressures at different sites (gastric, bladder and rectal) were similar, and an excellent agreement was found between alternative sites and Pes. |
| Chieveley-Williams et al., 2002 [37] | Small sample size, different measurement systems (fluid-filled and air-filled), relative and absolute positions of the catheters, different pathologies, varying frequency response of the systems with time. | ΔPes/ΔCVP ratio varied between 0.8 and 2.1, and the ΔPga/ΔPbl ratio varied between 0.6 and 1.3. Reducing ventilator assistance, the variation in ΔCVP was related to the variation of ΔPes. |
| Biselli and Nobrega, 2017 [38] | Small sample size, cardiac artifacts, high variability of inspiratory compliance. | ΔCVP highly correlated with ΔPaw during the Muller maneuver, comparable to that between ΔPes and ΔPaw. CVP had good performance for measuring WOB (R2 = 0.89) and intrathoracic pressure swings (R2 = 0.75) compared to Pes. |
| Colombo et al., 2020 [39] | Stable hemodynamics and no clear evidence of hypervolemia, early and severe ARDS were not included, no comparison between ΔCVP and diaphragm electrical activity or thickening. | ΔCVP identified strong inspiratory efforts with an area under the curve >0.9 both at ZEEP and during CPAP. |
| Lassola et al., 2021 [40] | Small sample size, limited timeframe, pressure support at enrolment set by the clinician, transdiaphragmatic pressure and intrinsic PEEP not measured, only COVID-19-related acute respiratory failure. | Reducing support, ΔPes and ΔCVP increased in a similar way (5 [3; 8] vs. 8 [14; 13] vs. 12 [6; 16] and 4 [3; 7] vs. 8 [5; 9] vs. 10 [7; 11] cmH2O, respectively); ΔCVP was significantly associated with ΔPes with R2 = 0.810. |
| Ostrander et al., 1977 [41] | Small sample size, non-clinical physiological study. | ΔCVP was 55% of ΔPpl at low mean CVP and 20% of ΔPpl at high CVP values. |
| Hedstrand et al., 1976 [42] | Small sample size, different measurement systems (fluid and air-filled), physiological study. | ΔCVP/ΔPes ratio varied significantly: 0.28 (0.12–0.44) in supine, 0.42 (0.25–0.56) in semirecumbent and 0.68 (0.34–1.40) in seated position. |
| Hylkema et al., 1983 [43] | Small sample size, different measurement systems (fluid and air-filled). | ΔPes was higher than ΔCVP, and the measurements only weakly correlated (r = 0.47). |
| Bellemare et al., 2007 [44] | Different right and left heart filling volumes could influence ΔCVP and ΔPes correlation. | Bias between ΔCVP and ΔPes was 2.9 cmH2O with R2 = 0.43. |