The increase in cardiac output induced by a decrease in positive end-expiratory pressure reliably detects volume responsiveness: the PEEP-test study

Table 1 Patient characteristics at inclusion

	Total population (n = 64)	Volume responsive (n = 31)	Volume unresponsive (n = 33)	p value
General characteristics
Male, n (%)	40 (63)	23 (74)	17 (52)	0.106
Age, years	63 ± 15	68 ± 10	58 ± 17	0.005
SAPS II	46 (34–60)	47 (38–63)	40 (33–56)	0.317
Weight, kg	81 (70–95)	76 (67–89)	82 (74–98)	0.087
Height, cm	170 ± 10	170 ± 10	170 ± 10	0.850
ARDS, n (%)	42 (66)	20 (65)	22 (67)	0.789
Septic shock, n (%)	28 (44)	15 (48)	13 (39)	0.636
Mortality, n (%)	26 (41)	15 (48)	11 (33)	0.332
IAP, mmHg	13 (10–15)	13 (11–14)	13 (10–16)	0.644
Respiratory characteristics
Vt, mL/kg predicted body weight	6.2 ± 0.6	6.3 ± 0.7	6.1 ± 0.6	0.494
RR, breaths/min	26 ± 5	26 ± 4	25 ± 5	0.852
PaO₂/FiO₂, mmHg	190 (138–266)	185 (135–256)	200 (144–272)	0.722
PEEP, cmH₂O	12 ± 3	12 ± 2	12 ± 3	0.883
PEEP_t, cmH₂O	13 ± 3	13 ± 2	13 ± 3	0.919
Plateau pressure, cmH₂O	26 ± 4	25 ± 5	27 ± 3	0.090
Driving pressure, cmH₂O	13 ± 4	12 ± 4	14 ± 3	0.087
Respiratory system compliance, mL/cmH₂O	34 ± 12	38 ± 15	30 ± 8	0.063
R/I ratio*	0.70 ± 0.29	0.68 ± 0.36	0.72 ± 0.22	0.742
Hemodynamic characteristics
Lactate, mmol/L	1.8 (1.4–2.5)	2 (1.5–3.3)	1.6 (1.3–1.9)	0.009
GEDVi, mL/m²	703 ± 188	689 ± 158	715 ± 214	0.215
EVLWi, mL/kg	15 ± 5	14 ± 4	16 ± 6	0.116
PVPI	2.8 (2.2–3.7)	2.7 (2.1–3.7)	2.9 (2.2–3.8)	0.687
Norepinephrine, n (%)	57 (89)	27 (87)	30 (91)	0.930
Norepinephrine dosage, µg/kg/min	0.2 (0.1–0.7)	0.3 (0.1–1.1)	0.2 (0.1–0.6)	0.227
Sinus rhythm, n (%)	57 (89)	29 (94)	28 (85)	0.475
Atrial extrasystoles, n (%)	4 (6)	2 (6)	2 (6)
Atrial fibrillation, n (%)	3 (5)	0	3 (9)

ARDS Acute respiratory distress syndrome, EVLWi Extravascular lung water indexed for predicted body weight, FiO₂ Fraction of inspired oxygen, GEDVi Global end-diastolic volume indexed for body surface, PaO₂ Arterial partial pressure of oxygen, IAP Intra-abdominal pressure, PEEP Positive end-expiratory pressure, PEEP_t Total positive end-expiratory pressure, PVPI Pulmonary vascular permeability index, R/I Recruitment-to inflation, RR Respiratory rate, SAPS II Simplified acute physiology score II, Vt Tidal volume
Values are expressed as n (%), mean ± standard deviation or median (interquartile range)
The p value corresponds to the comparison between volume responders and volume non-responders
^*Calculated in 20 volume responsive patients and 22 volume non-responsive patients

ISSN: 1364-8535