Methods
Outcome parameter
Duration of mechanical ventilation and of ICU stay, frequency and cause of readmission to
the ICU and length of hospital stay were recorded. Extubation was performed at the discretion
of the attending physician when hemodynamics were stable for half an hour, temperature was
higher than 36 °C, and the patients breathed spontaneously reaching adequate blood gases and
were cooperative. Patients were transferred from the ICU to the intermediate care unit when
they met the following criteria: Extubated, SpO2 higher than 94% with oxygen insufflation up
to 6 l min-1, stable hemodynamics with only minor doses of inotropes, i.e. dobutamine 5 mg
kg-1 min-1 and milrinon 0.3 mg kg-1 min-1. ICU discharge decisions were made by the
consultant intensivist on-duty.
Readmission was defined as admission to the ICU of a patient who had previously been
admitted to the ICU during the same hospitalisation period. Causes of readmission were
defined as follows: cardiovascular = cardiac arrest needing cardiopulmonary resuscitation
prior to ICU admission, shock requiring vasopressor/inotropic drugs, chest pain, arrhythmia,
cardiac failure; respiratory = acute lung injury and acute respiratory distress syndrome, acuteon-chronic respiratory failure and impaired respiratory function requiring non-invasive or
invasive mechanical ventilation; renal = acute renal failure requiring renal replacement
therapy; reoperation = reoperation with the need of postoperative intensive care treatment.
Patients were discharged from the hospital at the discretion of the department of cardiac
surgery.
Statistics
Differences in ventilation and discharge times between the four groups were analysed using
one-factorial ANOVA with post-hoc Tukey’s honestly significant difference test. Differences
in times between group A and group B were analysed using the T-test.
Results
No significant differences between the four groups could be detected for duration of
ventilation, duration of ICU time, readmission to the ICU, or length of hospital stay (see
Supplemental Table 1).
When looking post-hoc at group A and group B, i.e. patients with or without alveolar
derecruitment after OS, a trend to more readmissions to the ICU and longer hospital stay in
group B could be detected. No significant differences could be detected for ICU duration (see
Supplemental Table 2). The reasons for readmission to the ICU were three times pulmonary,
one time cardiovascular, and one time reoperation in group B compared to one time
cardiovascular in group A.
Supplemental Table 1
Group
A_RM
A_NRM
B_RM
B_NRM
P
Ventilation time [h]
17 (13)
14 (4)
18 (19)
64 (198)
0.458
ICU time [h]
44 (37)
37 (39)
57 (54)
112 (244)
0.536
8 (4)
8 (4)
10 (5)
12 (9)
0.230
Hospital discharge time [d]
ICU, intensive care unit; p, ANOVA. Data are presented as mean (SD).
Supplemental Table 2
Group
A
B
p
Ventilation time (h)
16 (9)
41 (140)
0.307
ICU duration (h)
41 (38)
61 (73)
0.638
1
5
0.063
8.1 (3.5)
10.8 (7.1)
0.078
ICU readmission (n)
Length of hospital stay [d]
p, t-test or χ2-test, as appropriate. Data are presented as mean (SD) or n.