Effect of the prone position on mechanical power in elective surgical patients under general anesthesia: A prospective observational study

Article Figures & Data

Table 1

- Patients’ demographics (N=76).

Patients’ characteristics	n (%)
Age median, year (IQR)	54 (18-81)
Female gender	38 (50.0)
BMI (kg/m²), median (IQR)	30.4 (20-39.9)
Predicted body mass, mean±SD	62±9
BMI <30	38 (50.0)
BMI ≥30	38 (50.0)
Operation duration (hour), median (IQR)	4 (1-6)
Current smoker	25 (32.9)
Hypertension	38 (50.0)
Coronary artery disease	11 (14.5)
Diabetes mellitus	21 (27.6)

Values are presented as numbers and percentages (%), median and interquartile range (IQR), or mean ± standard deviation (SD).
BMI: body mass index

Table 3

- Comparison of quantitative parameters according to conditions.

Parameters	T1	T2	T3	T4	T5	P-values^*
MP (J/min)	6.57±1.3	7.17±1.25	7.77±1.36	7.64±1.51	7.1±1.48	<0.001
MP (J/min)	6.57 (3.81-11.39)	7.1 (4.38-11.05)	7.52 (4.56-11.11)	7.49 (4.58-15.52)	6.91 (3.69-13.03)	<0.001
P peak (cmH₂O)	17.06±3.81	19.25±3.83	20.94±4.12	20.25±3.47	18.04±3.9	<0.001
P peak (cmH₂O)	17 (11-30)	19 (12-31)	20 (12-31)	20 (12-29)	18 (9-27)	<0.001
P plateau (cmH₂O)	16.66±3.78	18.79±3.8	20.38±3.96	19.69±3.35	17.63±4.36	<0.001
P plateau (cmH₂O)	17 (10-30)	18 (12-30)	20 (11-30)	20 (11-28)	17 (8-32)	<0.001
DP (cmH₂O)	11.77±3.81	13.94±3.86	15.52±3.93	14.76±3.32	12.56±4.05	<0.001
DP (cmH₂O)	12 (5-27)	13 (8-27)	15 (6-25)	15 (6-23)	12 (3-24)	<0.001
C (ml/cmH₂O)	67.31±18.24	53.08±15.19	46.97±15.79	48.1±13.72	62.65±24.16	<0.001
C (ml/cmH₂O)	65 (22-113)	51 (23-94)	45 (22-136)	45 (28-96)	58 (25-150)	<0.001
TV (ml)	499±18.08	497±23.06	501±24.55	502±49.8	509±44.9	0.66
TV (ml)	497 (451-587)	496 (375-572)	499 (431-571)	498 (441-683)	500 (407-682)	0.66

Values are presented as mean ± standard deviation and median (minimum-maximum).
↵* Friedman test.
P: pressure, MP: mechanical power, TV: tidal volume, DP: driving pressure, C: compliance, T1: 15th minute in the supine position, T2: 15th minute into the first prone position, T3: at the first hour in the prone position, T4: at the conclusion of the surgery in the final prone position, T5: in the final supine position, 15 minutes after return

Table 4

- Comparison of mechanical power according to body mass index groups.

Values are presented as mean ± standard deviation (SD) and median (minimum-maximum).
↵* Independent samples t-test.
↵** Mann Whitney U test.
BMI: body mass index, H: hour, MP: mechanical power, T1: 15th minute in the supine position, T2: 15th minute into the first prone position, T3: at the first hour in the prone position, T4: at the conclusion of the surgery in the final prone position, T5: in the final supine position, 15 minutes after return

Table 5

- Comparison of the effect of position on mechanical power change according to body mass index group.

Values are presented as mean ± standard deviation (SD) and median (minimum-maximum).
↵* Mann Whitney U test,
↵** Wilcoxon test.
MP: mechanical power, BMI: body mass index, T1: 15th minute in the supine position, T2: 15th minute into the first prone position, T4: at the conclusion of the surgery in the final prone position, T5: in the final supine position, 15 minutes after return