Figures
- FIGURE 1
Flowchart after arrival at the intensive care unit (ICU). The patients were randomised to either volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV) including a recruitment manoeuvre (RM) as the first line of treatment. The mechanical ventilation was thereafter set to pressure-regulated volume control (PRVC) in all patients until recovery from anaesthesia when the ventilator was switched to pressure-support ventilation (PSV) to facilitate spontaneous breathing. Figure created with BioRender.com.
- FIGURE 2
There was a significantly lower particle flow rate (PFR) when using pressure-regulated volume control (PRVC) compared to volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). Ventilation with pressure support ventilation (PSV) resulted in significantly higher PFR compared to PRVC. Statistical tests were conducted using the Mann–Whitney test. Statistical significance was defined as p<0.0001 (****) and p<0.05 (*).
- FIGURE 3
No significant difference was found in either ventilator mode when comparing particle flow rate (PFR) before and after the recruitment manoeuvre (RM). There was no significant difference between volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) before and after the recruitment manoeuvre. ns: not significant.
- FIGURE 4
a) Distribution of particles according to size in the different ventilation modes. When looking at particle flow rate (PFR) according to the different particle size bins (1–8) we can distinguish distinct patterns linked to different ventilation modes. In pressure support ventilation (PSV), there was a significantly higher PFR for all particle sizes (1–8) compared to the other ventilation modes. Statistical tests were conducted using the Kruskal–Wallis test. b) PFR for particle sizes 1–4 in the different ventilation modes. A significant difference was found between pressure-regulated volume control (PRVC) and pressure-controlled ventilation (PCV) for particle sizes 1–4. A significant difference between PRVC and volume-controlled ventilation (VCV) was found for particle sizes 1–3. No difference was found when comparing VCV to PCV for particle sizes 1–4. Statistical significance was defined as p<0.001 (***), p<0.01 (**), p<0.05 (*) and p>0.05 (not significant, ns).
Tables
- TABLE 1
Haemodynamic parameters, train-of-four (TOF) and blood gases during measurement at arrival in the intensive care unit (baseline), before and after recruitment manoeuvre, and before extubation
Parameters Baseline Before recruitment manoeuvre After recruitment manoeuvre Ending SBP mmHg 104.9±3.1 116.4±3.1 118.2±2.4 127.6±3.5 DBP mmHg 54.5±1.8 60.2±2.2 60.9±2.0 62.7±2.1 MAP mmHg 69.8±2.1 77.3±2.3 77.7±2.0 81.2±2.2 CVP mmHg 1.3±0.8 3.4±0.7 3.4±0.8 6.6±0.9 HR beats·min−1 76.9±1.9 75.8±1.9 74.1±2.2 80.4±2.2 SAT % 98.5±0.4 98.8±0.4 99.5±0.2 97.8±0.4 TOF % 92.9±5.3 PH 7.38±0 7.35±0 PCO2 mmHg 38.7±0.8 43.2±1.1 PO2 mmHg 132.8±5.7 98.3±3.3 Data presented as mean±sem. SBP: systolic blood pressure; DBP: diastolic blood pressure; MAP: mean arterial pressure; CVP: central venous pressure; HR: heart rate; SAT: saturation; PCO2: carbon dioxide tension; PO2: oxygen tension.
- TABLE 2
Ventilator settings and respiratory parameters at arrival in the intensive care unit (baseline), before and after recruitment manoeuvre, and before extubation
Parameters Baseline Before recruitment manoeuvre After recruitment manoeuvre Ending Ventilation mode VCV:PCV (1:1) VCV:PCV (1:1) PRVC PSV PEEP cmH2O 5.2±0.1 5.2±0.1 5.1±0.1 2.4±0.2 PIP cmH2O 17.0±0.9 17.0±0.5 14.6±0.4 12.8±0.2 Pmean cmH2O 8.9±0.2 9.0±0.3 8.7±0.2 5.1±0.2 PS cmH2O, in PCV and PSV 11.0±0.6 10.9±0.6 10.0±0.1 RR breaths·min−1 14.4±0.2 14.4±0.3 14.3±0.2 16.2±1.0 VT INSP mL 509.0±15.6 518.5±16.2 506.6±11.2 586.5±37.8 VT EXP mL 501.7±15.8 507.0±15.9 496.1±10.7 580.7±41.5 MV L·min−1 7.3±0.3 7.2±0.2 7.1±0.2 8.6±0.3 Cdyn mL/cmH2O 51.5±2.8 53.3±2.7 54.4±2.0 52.8±4.4 FIO2 % 42.0±1.0 40.7±0.8 40.0±0.9 32.2±0.6 I:E 1:2 1:2 1:2 Data presented as mean±sem. PEEP: positive end expiratory pressure; PIP: peak inspiratory pressure; Pmean: mean pressure; PS: pressure support; RR: respiratory rate; VT: tidal volume; MV: minute ventilation; Cdyn: dynamic compliance; FIO2: inspiratory oxygen fraction; I:E: inspiratory–expiratory ratio; VCV: volume-controlled ventilation; PCV: pressure-controlled ventilation; PRVC: pressure-regulated volume control; PSV: pressure support ventilation.
- TABLE 3
Patient demographics
Volume-controlled ventilation (VCV) Pressure-controlled ventilation (PCV) Total Patients, n 15 15 30 Sex male/female, n (%) 13 (87)/2 (13) 9 (60)/ 6 (40) 22 (73)/8 (27) Type of surgery, n CABG 8 7 15 AVR 6 4 10 CABG and AVR 1 4 5 Age years, mean±sd 70.3±11.1 67.5±9.4 68.9±10.2 Smoking No No No Normal chest radiograph Yes Yes Yes Normal renal function Yes Yes Yes EF>55% Yes Yes Yes CABG: coronary artery bypass grafting; AVR: aortic valve replacement.
