SUPPLEMENTAL DIGITAL CONTENT
SUPPLEMENTAL DIGITAL CONTENT 1: Agreement between changes in invasive and
noninvasive mean arterial pressure measurements in patients with circulatory failure
(n=57).
Legend: Bland-Altman analysis of the agreement between the mean of 3 consecutive invasive and noninvasive
measurements of changes in mean arterial pressure (MAP). Thick horizontal lines represent the mean bias, thin
continuous lines the limits of agreement (2 standard deviations), and the dotted lines their 95% confidence
interval.
Regression equations linking the bias and change in MAP were:
Arm: y=0.09+0.17x; constant bias of 0.09% [standard error: 0.82], p=0.91); proportional bias of 0.17 [0.04], p=0.0001].
Ankle: y=0.08+0.17x; constant bias of 0.08% [1.67], p=0.96); proportional bias of 0.17 [0.08], p=0.04].
Thigh: y=1.69+0.09x; constant bias of 1.69% [1.13], p=0.14); proportional bias of 0.09 [0.06], p=0.12].
SUPPLEMENTAL DIGITAL CONTENT 2: ARE ISOLATED READINGS OF NIBP SUITABLE?
When analyzing the agreement between the first pair of IABP and NIBP readings, the mean bias was
3.2±5.2, 2.7±8.5 and 4.7±7.0 mmHg, for the arm, ankle and thigh, respectively, i.e., similar to that
found when averaging 3 consecutive readings of each technique.
In patients with circulatory failure, the AUC of the first NIBP reading to detect an invasive MAP
<65mmHg was 0.97 [0.93-1], 0.92 [0.86-0.98] and 0.94 [0.88-0.99], for the arm, ankle and thigh,
respectively. The AUC of the first NIBP reading to detect a >10% increase in invasive MAP after
cardiovascular intervention was 0.98 [0.95-1], 0.88 [0.76-0.95], 0.88 [0.76-0.95].Therefore, averaging
3 consecutive NIBP measurements did not significantly improve the performance of NIBP.
SUPPLEMENTAL DIGITAL CONTENT 3: IMPACT of CLINICAL FACTORS on NIBP ACCURACY.
 Presence of circulatory failure:
The agreement between NIBP and IABP readings of map was similar when comparing subgroups of
patients in circulatory failure or not.
Agreement between invasive and noninvasive mean arterial pressure measurements with
respect to the presence of circulatory failure (n=83) or not (n=67).
Legend: Bland-Altman analysis of the agreement between the mean of 3 consecutive invasive and noninvasive
measurements of changes in mean arterial pressure (MAP). Thick horizontal lines represent the mean bias, thin
continuous lines the limits of agreement (2 standard deviations), and the dotted lines their 95% confidence
interval.
Regression equations linking the bias and MAP were:
Arm.
Ankle.
Thigh.
No circulatory failure: y=-2.3+0.1x; constant bias of -2.3 mmHg [standard error: 4.6], p=0.61); proportional bias of 0.1 [0.06], p=0.11].
Circulatory failure: y=-9.3+0.2x; constant bias of -9.3 mmHg [3.3], p=0.006); proportional bias of 0.2 [0.05], p=0.0006].
No circulatory failure: y=10.6-0.08x; constant bias of 10.6 mmHg [7.9], p=0.18); proportional bias of -0.08 [0.10], p=0.44].
Circulatory failure: y=8.7-0.10x; constant bias of 8.7 mmHg [4.7], p=0.07); proportional bias of -0.10 [0.07], p=0.15].
No circulatory failure: y=7.1+0.009x; constant bias of 7.1 mmHg [7.0], p=0.31); proportional bias of 0.009 [0.09], p=0.92].
Circulatory failure: y=-2.6+0.10x; constant bias of -2.6 mmHg [5.2], p=0.62); proportional bias of 0.10 [0.08], p=0.18].
European Society of Hypertension criteria (20) applied to the validation of noninvasive
measurements of mean arterial pressure in patients with circulatory failure (n=83).
Difference
between the
2 techniques
Arm Ankle Thigh
Criteria of the European
Society of Hypertension
n=246
n=246
n=221
3 out of 3
criteria
required
2 out of 3
criteria
required
≤ 5 mmHg
76 %
55 %
56 %
≥65 %
≥ 73%
≤ 10 mmHg
95 %
83 %
76 %
≥ 81%
≥ 87%
≤ 15 mmHg
98 %
92 %
93 %
≥ 93%
≥ 96%
Legend: NIBP,
noninvasive
blood pressure;
IABP, intra-arterial blood pressure; MAP, mean arterial pressure;
The comparisons between IABP and NIBP (individual measurements rather than the mean
of consecutive readings) have to be analyzed to determine the number of comparisons
falling within the 5, 10 and 15mmHg error bands.
- First, for NIBP to pass, there must be a minimum of 65, 81 and 93% of the comparisons
falling within 5, 10 and 15mmHg, respectively. Arm NIBP passed but not ankle and thigh
NIBP.
- Second, there must be a minimum of 2 criteria fulfilled among ≥63% of the comparisons
within 5mmHg, ≥87% of the comparisons within 10mmHg or ≥96% of the comparisons
within 15mmHg. Arm NIBP passed.
- Third, for arm NIBP, 19 patients (78%, minimum required: 66%), had at least two of their
three comparisons lying within 5mmHg. Arm NIBP passed.
- Last, 12 patients (14%, maximum tolerated: 9%) had all 3 of their comparisons over 5
mmHg apart. Arm NIBP did not pass this last stage.
Site of insertion of the intra-arterial catheter:
The agreement between NIBP and IABP readings of map seemed similar when comparing subgroups
of patients according to the site of the arterial line.
Agreement between invasive and noninvasive mean arterial pressure measurements
according to the intra-arterial catheter site of insertion.
Legend: Bland-Altman analysis of the agreement between the mean of 3 consecutive invasive and noninvasive
measurements of mean arterial pressure (MAP).
The mean bias for the femoral and the radial site was 4.1±4.5 and 3.1±5.3 mmHg for arm NIBP, 5.5±6.5 and
1.6±8.1 mmHg for ankle NIBP and 7.4±6.6 and 4.7±6.9 mmHg for thigh NIBP, respectively.
NIBP, non-invasive blood pressure monitoring.
Regression equations linking the bias and MAP were:
Arm.
Ankle.
Thigh.
Femoral artery catheter: y=-10.1+0.2x; constant bias of -10.1 mmHg [standard error: 3.6], p=0.007); proportional bias of 0.2 [0.05], p=0.0002].
Radial artery catheter: y=-9.1+0.2x; constant bias of -9.1 mmHg [3.3], p=0.004); proportional bias of 0.2 [0.04], p=0.0001].
Femoral artery catheter: y=11.7-0.09x; constant bias of 11.7 mmHg [5.3], p=0.03); proportional bias of -0.09 [0.07], p=0.23].
Radial artery catheter: y=-4.2+0.08x; constant bias of -4.2 mmHg [5.1], p=0.41); proportional bias of 0.08 [0.07], p=0.26].
Femoral artery catheter: y=-16.5+0.3x; constant bias of -16.5 mmHg [6.5], p=0.01); proportional bias of 0.34 [0.09], p=0.0005].
Radial artery catheter: y=-2.0+0.09x; constant bias of -2.0 mmHg [4.4], p=0.66); proportional bias of 0.09 [0.06], p=0.13].
 Impact of the oscillometric NIBP device
The 28 patients with the M3000A™ NIBP module (and the B850™ IABP module) did not
significantly differ from the 122 patients connected to the M1008B™ module (and the
M1006B™ IABP module) for any of the items of table 1. The agreement between invasive
and noninvasive MAP was close from a NIBP device to another, (except an opposite bias for
the ankle)[see SUPPLEMENTAL DIGITAL CONTENT figure 4]: mean bias of 3.8±5.2 vs 1.9±3.8
mmHg for the arm, 5.0±6.8 vs -4.7±6.9mmHg for the ankle and 6.7±6.5 vs 2.5±7.2mmHg for
the thigh, with the M1008B™ and the M3000A™ module, respectively.
Agreement between invasive and noninvasive measurements of mean arterial pressure
according to the NIBP device.
Legend: Bland-Altman analysis of the agreement between the mean of 3 consecutive invasive and noninvasive
measurements of mean arterial pressure (MAP).
The oblique line represents the regression line linking the bias and MAP:
Arm:
M1008B™: y=-9.23+0.18x; constant bias of -9.23 mmHg [standard error: 2.66], p=0.0007); proportional
bias of 0.18 [0.04], p<0.0001].
M3000A™: y=-3.1+0.07x; constant bias of -3.1 mmHg [4.4], p=0.49); proportional bias of 0.07 [0.06], p=0.27].
Ankle:
M1008B™: y=-4.75+0.13x; constant bias of -4.75 mmHg [3.67], p=0.20); proportional bias of 0.13 [0.05], p=0.008].
M3000A™: y=11.24-0.20x; constant bias of 11.24 mmHg [6.94], p=0.12); proportional bias of -0.20 [0.09], p=0.03].
Thigh:
M1008B™: y=-9.48+0.23x; constant bias of -9.48 mmHg [standard error: 3.72], p=0.01); proportional bias of 0.23 [0.05], p<0.0001].
M3000A™: y=7.86-0.07x; constant bias of 7.86 mmHg [standard error: 9.00], p=0.39); proportional bias of -0.07 [0.12], p=0.55].
 Impact of the time of measurements with respect to the onset of circulatory failure.
Twenty-two (27%) patients were included during the first 6 hours after the onset of the
circulatory failure (67% during the first 24 hours). In this subgroup of patients, the agreement
between IABP and NIBP for MAP was similar to that found in the whole population. Further, the
ability to detect hypotensive and therapy-responding patients was similar to that observed in the
whole population of patients with circulatory failure.
Agreement between invasive and noninvasive mean arterial pressure measurements in
patients included within the 6 first hours after the onset of circulatory failure.
Legend: Bland-Altman analysis of the agreement between the mean of 3 consecutive invasive and noninvasive
measurements of mean arterial pressure (MAP).
Regression equations linking the bias and change in MAP were:
Arm: y=-7.31+0.14x; constant bias of -7.31 mmHg [standard error: 7.00], p=0.31); proportional bias of 0.14 [0.10], p=0.20].
Ankle: y=-16.55+0.27x; constant bias of -16.54 mmHg [10.11], p=0.12); proportional bias of 0.27 [0.15], p=0.09].
Thigh: y=-6.06+0.13x; constant bias of -6.06 mmHg [12.02], p=0.62); proportional bias of 0.13 [0.19], p=0.49].
Receiver operating characteristic (ROC) curves for noninvasive detection of hypotension
(A) and response to therapy (B) in patients included within the 6 first hours after the onset
of circulatory failure.
Legend: Hypotension denotes a mean arterial pressure below 65 mmHg. Response to therapy was defined by a
>10% increase in mean arterial pressure following a cardiovascular intervention. The analysis was based on the
mean of 3 consecutive measurements with each technique.
AUC, area under the ROC curve. MAP, mean arterial pressure.
 Impact of the dosage of norepinephrine
Among the 62 patients (one excluded because of NIBP failure) receiving norepinephrine (0.4±0.3
µg/kg/min), we did not found any significant correlation between the bias (absolute value of [invasivenoninvasive MAP]) and the norepinephrine dosage, for any of the 3 sites, arm, ankle and thigh (r²<0.05, p>0.1).
As only 2 and 4 patients received epinephrine (0.15±0.14 µg/kg/min) and dobutamine (10±3 µg/kg/min),
respectively, no specific analysis was deemed possible for the influence of these vasoactive drugs on NIBP
accuracy.

Was the sedation level an inclusion bias?
Thigh NIBP measurements were not performed in non-deeply sedated patients (Ramsay sedation
scale≤4). Of note, our results (and conclusions) do not appear altered by the analysis of patients who
undergone NIBP measurements at all the three sites:
- The AUC for the detection of hypotension was:
Arm: 0.98 [0.91-1]
Ankle: 0.92 [0.83-0.97]
Thigh: 0.93 [0.85-0.98]
- The AUC for the detection of response to therapy was:
Arm: 0.99 [0.91-1]
Ankle: 0.92 [0.81-0.98]
Thigh: 0.96 [0.87-0.99]