Pulse pressure variation and pleth variability index as predictors of fluid responsiveness in patients undergoing spinal surgery in the prone position

Figures & data

Figure 1 Flow diagram of this study.

Table 1 Patient characteristics and perioperative details

	Overall (n=53)	Supine			Prone
		Responders (n=40)	Non-responders (n=13)	P-value	Responders (n=27)	Non-responders (n=26)	P-value
Age, years	67 (61–73)	67 (61–73)	68 (61–74)	0.818	66 (61–71)	68 (61–75)	0.349
Female, n	32 (60.4)	26 (65.0)	6 (46.2)	0.227	17 (63.0)	15 (57.7)	0.695
Height, cm	158.1±7.5	157.1±7.5	161.1±7.2	0.100	158.3±7.6	157.8±7.6	0.788
Weight, kg	62.1±10.5	61.5±11.0	64.1±8.8	0.437	61.0±11.0	63.2±10.0	0.458
BMI, kg/m^2	24.7±2.8	24.8±3.0	24.6±2.1	0.872	24.2±2.6	25.3±2.9	0.142
ASA classification, I/II/III	15/27/11	10/23/7	5/4/4	0.251	7/13/7	8/14/4	0.715
Comorbidities, n				0.436			0.452
Hypertension	31 (59)	25 (63)	6 (46)		16 (59)	15 (58)
Diabetes mellitus	16 (30)	11 (28)	5 (39)		10 (37)	6 (23)
Coronary artery disease	3 (5)	2 (5)	1 (8)		1 (4)	2 (8)
Stroke	2 (4)	1 (3)	1 (8)		0 (0)	2 (8)
Medications, n				0.729			0.948
Calcium channel blocker	16 (30)	12 (30)	4 (31)		7 (26)	9 (35)
Beta blocker	3 (6)	2 (5)	1 (8)		1 (4)	2 (8)
ACE inhibitor	1 (2)	1 (3)	0 (0)		1 (4)	0 (0)
ARB	19 (36)	16 (40)	3 (23)		10 (37)	9 (35)
Diuretics	6 (11)	4 (10)	2 (15)		3 (11)	3 (11)
Levels operated, 1/2/3/4	32/15/4/2	22/13/3/2	10/2/1/0	0.515	20/5/1/1	12/10/3/1	0.158
Duration of surgery, min	225 (208–270)	233 (203–279)	215 (208–233)	0.362	225 (200–245)	228 (210–296)	0.212
Fluid administration, mL	1,950 (1,775–2,325)	1,975 (1,810–2,475)	1,920 (1,555–2,145)	0.282	1,910 (1,600–2,180)	2,100 (1,830–2,450)	0.087
pRBCs transfusion, mL	109.4±195.0	125.0±207.0	61.5±148.8	0.238	90.7±191.7	128.9±200.2	0.482
Blood loss, mL	600 (400–800)	600 (400–875)	550 (450–750)	0.901	600 (400–700)	600 (475–1025)	0.432

Note: Data are presented as the mean ± SD, median (interquartile range) or number of patients (%).

Abbreviations: ACE, angiotensin-converting enzyme; ARB, angiotensin II receptor blocker; ASA, American Society of Anesthesiologists; BMI, body mass index; pRBCs, packed red blood cells.

Table 2 Hemodynamic variables and respiratory indices before and after fluid loading and changes in body position

	T1	T2	T3	T4
HR, beats/min	73.8±13.3	68.6±11.9*	68.4±10.5	65.9±9.8‡
MAP, mmHg	74.5±15.8	72.9±10.9	78.9±11.0^	77.4±9.3
Cardiac index, L/min/m^2	2.8 (2.3–3.4)	3.1 (2.7–4.1)*	2.7 (2.4–3.7)^	3.0 (2.6–4.0)‡
SVI, mL/m^2	38.4 (30.9–47.0)	45.0 (41.5–55.6)*	40.5 (35.0–48.8)^	45.3 (10.0–56.6)‡
PPV, %	14.0 (9.0–18.5)	7.0 (6.0–9.0)*	8.0 (6.0–10.0)	4.0 (3.0–7.0)‡
PVI, %	11.0 (7.0–14.5)	6.0 (4.0–8.0)*	8.0 (7.0–11.5)^	6.0 (4.0–8.0)‡
Cstat, mL/cmH2O	34.9 (30.4–46.8)	33.7 (29.5–43.0)*	32.5 (28.2–39.7)^	30.5 (27.9–38.5)‡
Pplat, cmH2O	14.0 (13.0–16.0)	15.0 (13.5–16.5)*	16.0 (15.0–17.0)^	16.0 (15.0–18.0)‡

Notes: Data are presented as the mean ± SD or median (interquartile range).

* P<0.05 compared with T1;

^ P<0.05 compared with T2;

‡ P<0.05 compared with T3. Cstat, static compliance of the respiratory system; Pplat, plateau airway pressure; T1, before fluid loading with patients in the supine position; T2, 5 minutes after fluid loading with patients in the supine position; T3, before fluid loading after placing patients in the prone position; T4, 5 minutes after fluid loading with patients in the prone position.

Abbreviations: HR, heart rate; MAP, mean arterial pressure; PPV, pulse pressure variation; PVI, pleth variability index; SVI, stroke volume index.

Table 3 Hemodynamic variables before and after fluid loading in responders and non-responders placed in the supine position

	Responders (n=40)		Non-responders (n=13)
	Before (T1)	After (T2)	Before (T1)	After (T2)
HR, beats/min	75.6±13.1	70.2±12.5*	67.9±12.6	63.6±8.6*
MAP, mmHg	74.4±16.6	72.6±10.0	74.9±13.7	73.7±13.9
Cardiac index, L/min/m^2	2.8 (2.2–3.6)	3.2 (2.8–4.2)*	2.8 (2.5–3.2)	2.9 (2.7–3.3)*
SVI, mL/m^2	34.4 (30.6–46.1)	46.9 (41.3–58.9)*	40.0 (37.8–51.2)	44.7 (42.7–55.2)*
PPV, %	16.0 (10.3–21.0)	7.5 (6.0–9.8)*	10.0 (8.0–14.0)^	7.0 (4.5–7.5)*
PVI, %	11.0 (9.0–15.0)	6.0 (4.0–9.0)*	7.0 (5.5–8.5)^	5.0 (4.5–7.0)*

Notes: Data are presented as the mean ± SD or median (interquartile range).

* P<0.05 compared with before fluid loading;

^ P<0.05 compared with baseline values (before fluid loading) in responders. T1, before fluid loading with patients in the supine position; T2, 5 minutes after fluid loading with patients in the supine position.

Abbreviations: HR, heart rate; MAP, mean arterial pressure; PPV, pulse pressure variation; PVI, pleth variability index; SVI, stroke volume index.

Table 4 Hemodynamic variables before and after fluid loading in responders and non-responders placed in the prone position

	Responders (n=27)		Non-responders (n=26)
	Before (T3)	After (T4)	Before (T3)	After (T4)
HR, beats/min	70.7±11.1	68.3±10.4*	66.1±9.4	63.4±8.7*
MAP, mmHg	78.2±9.9	77.5±8.1	79.7±12.3	77.4±10.5
Cardiac index, L/min/m^2	2.7 (2.3–3.6)	2.9 (2.6–3.9)*	2.9 (2.4–4.0)	3.0 (2.6–4.1)*
SVI, mL/m^2	38.2 (33.0–48.0)	44.5 (39.7–56.5)*	43.0 (38.1–54.2)^	46.4 (41.0–58.0)*
PPV, %	10.0 (8.0–10.0)	4.0 (3.0–7.0)*	6.5 (5.0–8.0)^	4.5 (3.8–7.3)*
PVI, %	10.0 (8.0–13.0)	6.0 (4.0–8.0)*	8.0 (6.8–9.0)^	6.5 (4.8–8.3)*

Notes: Data are presented as the mean ± SD or median (interquartile range).

* P<0.05 compared with before fluid loading;

^ P<0.05 compared with baseline values (before fluid loading) in responders. T3, before fluid loading after placing patients in the prone position; T4, 5 minutes after fluid loading with patients in the prone position.

Abbreviations: HR, heart rate; MAP, mean arterial pressure; PPV, pulse pressure variation; PVI, pleth variability index; SVI, stroke volume index.

Figure 2 Receiver operating characteristic curves, showing the ability of PPV (solid line) and PVI (dashed line) before volume loading to discriminate responders from non-responders.

Notes: (A) The supine position. The areas under the curves for PPV and PVI were 0.783 (95% CI 0.648–0.884, P<0.001) and 0.814 (95% CI 0.684–0.908, P<0.001), respectively. There was no significant difference between the areas under the curve of PPV and PVI (P=0.699). (B) The prone position. The areas under the curves for PPV and PVI were 0.781 (95% CI 0.646–0.883, P<0.001) and 0.756 (95% CI 0.618–0.863, P<0.001) respectively. There was no significant difference between the areas under the curve of PPV and PVI (P=0.766). The area under the curve for PVI in patients placed in the prone position was slightly smaller than in patients placed in the supine position, unlike for PPV.
Abbreviations: PPV, pulse pressure variation; PVI, pleth variability index.

Table 5 Prediction of fluid responsiveness by receiver operating characteristic curves of pulse pressure variation and pleth variability index

	AUROC curve (95% CI)	P-value	Cut-off value	Gray zone	Patients in the gray zone (%)	Sensitivity (%) (95% CI)	Specificity (%) (95% CI)
Supine
PPV	0.783 (0.648–0.884)	<0.001	10%	8.2%–13.9%	18 (34)	75.0 (58.8–87.3)	61.5 (31.6–86.1)
PVI	0.814 (0.684–0.908)	<0.001	8%	6.0%–11.4%	23 (43)	77.5 (61.5–89.2)	76.9 (46.2–95.0)
Prone
PPV	0.781 (0.646–0.883)	<0.001	7%	6.4%–10.4%	31 (58)	81.5 (61.9–93.7)	61.5 (40.6–79.8)
PVI	0.756 (0.618–0.863)	<0.001	8%	6.5%–10.7%	31 (58)	66.7 (46.0–83.5)	69.2 (48.2–85.7)

Abbreviations: AUROC, area under the receiver operating characteristic; PPV, pulse pressure variation; PVI, pleth variability index.

Table 6 Characteristics of the studies that investigated the ability of dynamic indices to predict fluid responsiveness in patients undergoing spinal surgery in the prone position

Study	Biais et al^Citation14	Yang et al^Citation15	Present study
Year	2010	2013	2018
Surgery	Scoliosis surgery	Lumbar spinal fusion	Lumbar spinal fusion
Positioning system	Four pads	Wilson frame	Jackson table
Age, years	48 (18–74)	56 (20–76)	66 (45–75)
Fluid bolus, mL	500 mL of colloid	6 mL/kg of colloid*	6 mL/kg of colloid*
Fluid administration, mL	–	2,612±1,354	2,095±559
Blood loss, mL	1,540±450	1,055±1,002	697±401
Definition of fluid responsiveness	Increase in CO ≥ 15%	Increase in SVI ≥ 10%	Increase in SVI ≥ 15%
Cut-off value (AUROC curve [95% CI])
Supine position
PPV	11% (0.949 [0.789–0.993])	15% (0.935 [0.870–0.999])	10% (0.783 [0.648–0.884])
FTc	–	358 ms (0.822 [0.682–0.961])	–
PVI	–	–	8% (0.814 [0.684–0.908])
Prone position
PPV	15% (0.959 [0.803–0.994])	14% (0.969 [0.912–1.000])	7% (0.781 [0.646–0.883])
FTc	–	331 ms (0.846 [0.706–0.985])	–
PVI	–	–	8% (0.756 [0.618–0.863])

Notes: Data are presented as the mean (range) or mean ± SD.

* Ideal body weight.

Abbreviations: AUROC, area under the receiver operating characteristic; CO, cardiac output; FTc, corrected flow time; PPV, pulse pressure variation; PVI, pleth variability index; SVI, stroke volume index.

BiaisMBernardOHaJCDegryseCSztarkFAbilities of pulse pressure variations and stroke volume variations to predict fluid responsiveness in prone position during scoliosis surgeryBr J Anaesth2010104440741320190260

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YangSYShimJKSongYSeoSJKwakYLValidation of pulse pressure variation and corrected flow time as predictors of fluid responsiveness in patients in the prone positionBr J Anaesth2013110571372023274783

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