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Table 3 Relationship between measurements and subsequent clinical adjustments of PEEP

From: Implementing a bedside assessment of respiratory mechanics in patients with acute respiratory distress syndrome

  PEEP at postmeasurement vs. at premeasurement  
Measured variables Decreased (n = 20) Unchanged (n = 27) Increased (n = 8) P value
Markers of overdistentiona
 Pplat, cmH2O 28 ± 5b 25 ± 4b 26 ± 2 0.013
 Elastance-derived PL,plat, cmH2O 21 [20–26]b 17 [16–20]b 18 [16–21] 0.034
 PL,end-insp, cmH2O 5 [3–18] 8 [4–9] 4 [0–10] 0.327
 Pdriv, cmH2O 15 ± 5 12 ± 4 13 ± 3 0.098
 PL,driv, cmH2O 12 ± 5 9 ± 4 9 ± 5 0.063
Risk of atelectasisa
 PL,end-exp, cmH2O −2 ± 5 −2 ± 5 −5 ± 5 0.335
Response to the incremental PEEP trialc
 Changes in Pdriv, cmH2O 2.0 [0–3.5] 1.0 [0–1.0] 0.5 [0–12] 0.169
 Changes in PL,driv, cmH2O 1.9 ± 2.5 0.7 ± 1.8 −0.3 ± 1.2 0.042
 Changes in PaO2/FiO2, mmHg −4 [−17 to 12] 0 [−18 to 14] 3 [−29 to 10] 0.226
 Changes in MAP, mmHg −2 [−10 to 3] −2 [2-9] −3 [−8 to 0] 0.675
Recruitabilityd
 Vder, ml 105 ± 61e 142 ± 106 208 ± 124e 0.036
  1. Abbreviations: P plat Airway plateau pressure, Elastance-derived P L,plat Elastance-derived transpulmonary plateau pressure, calculated using airway plateau pressure times the ratio of lung elastance to respiratory system elastance, P L,end-insp Transpulmonary pressure measured at end inspiration occlusion, P driv Driving pressure, P L,driv Lung driving pressure (i.e., difference between PL,end-insp and PL,end-exp, P driv driving pressure, measured by the difference between plateau pressure and total PEEP), P L,end-exp Transpulmonary pressure measured at the end-expiratory occlusion, MAP Mean arterial pressure, V der derecruited volume
  2. Continuous variables were described as mean ± SD and compared using one-way analysis of variance with the Bonferroni post hoc test, or described as median [IQR] and compared using the Kruskal-Wallis test with Dunn’s post hoc test, as appropriate. Bonferroni adjustment was not used. (Refer to main text for explanations.) There is some variation in the number of measurements because of missing data. We report the number of measurements in detail for each variable in the additional files
  3. aVariables reflecting the risks of overdistention and atelectasis were measured at clinical PEEP level
  4. b P < 0.05 PEEP-decreased vs. PEEP-unchanged
  5. cResponses to an increment of PEEP in 3–5 cmH2O, expressed per 1-cmH2O PEEP increase
  6. dAssessed by estimating the alveolar derecruitment with decreasing PEEP by 10 cmH2O
  7. e P < 0.05 PEEP-decreased vs. PEEP-increased
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