Flowchart of retrospective study and cohort selection criteria (a). A final cohort of 118 patients were identified and values of mean arterial pressure (MAP) (b) and heart rate (HR), (c) by time …
Intra-operative mean arterial pressure (MAP) and heart rate (HR) sampled every 5 min (Q5) were curated, processed, and formatted in a unique data matrix (a) (Figure 2—figure supplement 1). The …
The time-series signal between patients is not aligned (changes at specific time point might not reflect the same for each patient) and of different length due to the different duration of surgery (a…
The proportion of AIS grades at discharge for each cluster was mapped into the network and its association with the mean average mean arterial pressure (aMAP) per cluster explored. Clusters with …
Logistic regression models were fitted to study the potential non-linearity of the aMAP predictor as suggested by the exploratory analysis. Six different models were studied: naïve, linear, …
To find the optimal MAP range, a moving MAP range was computed and the time of MAP outside range calculated (a and d, example of the same patient for symmetric and asymmetric map range, …
We further explored the relationship of the distribution of patients in the network and the amount of time their MAP was out of a specific range (Figure 4). For each MAP range, the assortativity …
(a) The deviance of the binomial model used as cross-validation error (mean and standard deviation) in the LOOCV (see Methods) against the values of l (in log form). The two vertical doted lines …
AIS improve. N/A(n = 15) | AIS improve. NO(n = 61) | AIS improve. YES(n = 42) | Univariate p-value | |
---|---|---|---|---|
Age (years) | 0.12 | |||
Mean (SD) | 46.0 (17.6) | 45.3 (19.1) | 51.4 (19.7) | |
Median [min, max] | 45.5 [19.0, 87.0] | 47.0 [18.0, 82.0] | 55.0 [18.0, 86.0] | |
Missing | 1 (6.7%) | 2 (3.3%) | 1 (2.4%) | |
AIS admission | 0.013 | |||
A | 1 (6.7%) | 33 (54.1%) | 18 (42.9%) | |
B | 0 (0%) | 5 (8.2%) | 8 (19.0%) | |
C | 0 (0%) | 5 (8.2%) | 11 (26.2%) | |
D | 0 (0%) | 14 (23.0%) | 5 (11.9%) | |
E | 0 (0%) | 4 (6.6%) | 0 (0%) | |
Missing | 14 (93.3%) | 0 (0%) | 0 (0%) | |
AIS discharge | <0.0001 | |||
A | 0 (0%) | 35 (57.4%) | 0 (0%) | |
B | 0 (0%) | 5 (8.2%) | 5 (11.9%) | |
C | 1 (6.7%) | 4 (6.6%) | 15 (35.7%) | |
D | 0 (0%) | 14 (23.0%) | 17 (40.5%) | |
E | 1 (6.7%) | 2 (3.3%) | 5 (11.9%) | |
Missing | 13 (86.7%) | 1 (1.6%) | 0 (0%) | |
Surgery duration (min) | 0.66 | |||
Mean (SD) | 433 (167) | 392 (146) | 407 (181) | |
Median [min, max] | 432 [121, 725] | 389 [120, 728] | 343 [151, 950] | |
Missing | 1 (6.7%) | 2 (3.3%) | 1 (2.4%) | |
Surgery to discharge (days) | 0.33 | |||
Mean (SD) | 9.50 (2.12) | 18.8 (20.6) | 23.4 (23.8) | |
Median [min, max] | 9.50 [8.00, 11.0] | 11.0 [1.00, 128] | 14.5 [4.00, 120] | |
Missing | 13 (86.7%) | 4 (6.6%) | 2 (4.8%) | |
Dichotomized neurological level of injury at admission | 0.054 | |||
Cervical | 2.00 (13.3%) | 36 (59%) | 33 (78.6%) | |
Non-cervical | 13.00 (86.7%) | 25 (41%) | 9 (21.4%) |
Model | AIC | Residual df | Residualdeviance | Deviance | p-Value | LOOCV error |
---|---|---|---|---|---|---|
Null model | 141.26 | 102 | 139.26 | 0.246 | ||
Linear model | 134.8 | 101 | 130.80 | 8.46(vs. null model) | 0.0036**(vs. null model) | 0.231 |
Quadratic model | 128.48 | 100 | 122.48 | 8.32(vs. linear model) | 0.0039**(vs. linear model) | 0.210 |
Cubic model | 126.97 | 99 | 118.97 | 3.50(vs. quadratic model) | 0.061(vs. quadratic model) | 0.213 |
Natural Spline model (df = 2) | 128.29 | 100 | 122.29 | 8.50(vs. linear model) | 0.0035**(vs. linear model) | 0.210 |
Natural Spline model (df = 3) | 127.13 | 99 | 119.13 | 3.34(vs. quadratic model) | 0.067(vs. quadratic model) | 0.213 |
** p < 0.01.
Model: where average MAP (n = 103 patients) | ||||
---|---|---|---|---|
LOOCV: average observed accuracy = 0.66; average kappa statistic = 0.334 | ||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value |
Intercept | = –0.55 | 0.242 | –2.293 | 0.02183* |
Average MAP () | = 8.62 | 2.944 | 2.931 | 0.00338** |
Average MAP () | = –7.601 | 3.039 | –2.501 | 0.0123* |
*p < 0.05; **p < 0.01.
Model: , where average MAP; : average HR; length of surgery (min); days to AIS discharge (days); age; AIS admission D (‘yes’,’no’); AIS admission C (‘yes’,’no’); AIS admission B (‘yes’,’no’); AIS admission A (‘yes’,’no’); (AIS admission E was set as the reference level for AIS admission variable and is part of the intercept) (final n = 93) | |||||||||
---|---|---|---|---|---|---|---|---|---|
LOOCV: average observed accuracy = 0.688; average kappa statistic = 0.362 | |||||||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value | |||||
Intercept | = –1.530 | 121.8 | –0.013 | 0.99 | |||||
Average MAP () | = 7.398 | 3.112 | 2.377 | 0.017* | |||||
Average MAP () | = –8.053 | 3.530 | –2.281 | 0.022* | |||||
Average HR () | = –2.087 | 0.0245 | –0.851 | 0.394 | |||||
Length of surgery () | = 0.0011 | 0.0015 | 0.728 | 0.466 | |||||
Days to AIS discharge () | = 0.0037 | 0.0109 | 0.344 | 0.730 | |||||
Age () | = 0.0082 | 0.013 | 0.634 | 0.526 | |||||
AIS admission D () | = 1.454 | 1.218 | 0.012 | 0.990 | |||||
AIS admission C () | = 1.645 | 1.218 | 0.014 | 0.989 | |||||
AIS admission B () | = 1.585 | 1.218 | 0.013 | 0.989 | |||||
AIS admission A () | = 1.527 | 1.218 | 0.013 | 0.990 | |||||
Correlation matrix (Spearman) | |||||||||
Average MAP | AverageHR | Length of surgery | Days to AIS discharge | Age | AIS admission | ||||
Average MAP | 1 | ||||||||
Average HR | –0.126 | 1 | |||||||
Length of surgery | –0.152 | 0.101 | 1 | ||||||
Days to AIS discharge | 0.088 | –0.059 | 0.165 | 1 | |||||
Age | 0.006 | –0.245 | 0.011 | 0.022 | 1 | ||||
AIS admission | 0.024 | 0.003 | –0.01 | 0.258 | –0.13 | 1 | |||
*p < 0.05.
Model: , where : average HR; length of surgery (min); days to AIS discharge (days); age; AIS admission D (‘yes’,’no’); AIS admission C (‘yes’,’no’); AIS admission B (‘yes’,’no’); AIS admission A (‘yes’,’no’); (AIS admission E was set as the reference level for AIS admission variable and is part of the intercept) (final n = 93) | ||||
---|---|---|---|---|
LOOCV: average observed accuracy = 0.612; average kappa statistic = 0.17 | ||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value |
Intercept | = –1.585 | 138.2 | –0.011 | 0.991 |
Average HR () | = –0.0209 | 0.029 | –0.911 | 0.362 |
Length of surgery () | = 0.0016 | 0.00141 | 1.151 | 0.250 |
Days to AIS discharge () | = 0.0105 | 0.0106 | 0.993 | 0.320 |
Age () | = 0.0052 | 0.012 | 0.424 | 0.672 |
AIS admission D () | = 1.511 | 1.382 | 0.011 | 0.991 |
AIS admission C () | = 1.715 | 1.382 | 0.012 | 0.991 |
AIS admission B () | = 1.643 | 1.382 | 0.012 | 0.990 |
AIS admission A () | = 1.574 | 1.382 | 0.011 | 0.991 |
Model: , where average MAP; : average HR; length of surgery (min); days to AIS discharge (days); age (final n = 51) | ||||
---|---|---|---|---|
LOOCV: average observed accuracy = 0.63; average kappa statistic = 0.197 | ||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value |
Intercept | = –0.931 | 3.433 | –0.271 | 0.786 |
Average MAP () | = 10.79 | 5.014 | 2.153 | 0.031* |
Average MAP () | = –6.73 | 4.591 | –1.468 | 0.142 |
Average HR () | = –0.016 | 0.035 | –0.468 | 0.639 |
Length of surgery () | = 0.0039 | 0.0026 | 1.504 | 0.132 |
Days to AIS discharge () | = 0.0067 | 0.014 | 0.477 | 0.633 |
Age () | = –0.012 | 0.020 | –0.599 | 0.549 |
*p < 0.05.
Cervical (n = 71) | Non-cervical (n = 32) | |||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
NLI | C2 | C3 | C4 | C5 | C6 | C7 | C8 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10 | T11 | T12 | S1 | S5 |
Cases | 3 | 3 | 24 | 28 | 4 | 8 | 1 | 1 | 3 | 3 | 1 | 2 | 1 | 3 | 1 | 3 | 2 | 4 | 6 | 2 |
Model: , where average MAP; : average HR; length of surgery (min); days to AIS discharge (days); age; AIS admission D (‘yes’,’no’); AIS admission C (‘yes’,’no’); AIS admission B (‘yes’,’no’); (AIS admission A was set as the reference level for AIS admission variable and is part of the intercept, no AIS admission E was present in this cohort) (final n = 93) | ||||
---|---|---|---|---|
LOOCV: average observed accuracy = 0.688; average kappa statistic = 0.362 | ||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value |
Intercept | = 2.747 | 3.018 | 0.91 | 0.363 |
Average MAP () | = 7.594 | 3.056 | 2.485 | 0.013* |
Average MAP () | = –7.528 | 3.358 | –2.242 | 0.025* |
Average HR () | = –0.055 | 0.034 | –1.608 | 0.108 |
Length of surgery () | = 0.0014 | 0.0019 | 0.720 | 0.472 |
Days to AIS discharge () | = 0.0022 | 0.012 | 0.182 | 0.855 |
Age () | = 0.0079 | 0.016 | 0.482 | 0.630 |
AIS admission D () | = –0.747 | 0.87 | –0.840 | 0.730 |
AIS admission C () | = 0.745 | 0.80 | 0.925 | 0.355 |
AIS admission B () | = 0.301 | 0.88 | 0.346 | 0.401 |
*p < 0.05.
Model: , where average MAP; : average HR; length of surgery (min); days to AIS discharge (days); age; AIS admission D (‘yes’,’no’); AIS admission C (‘yes’,’no’); AIS admission B (‘yes’,’no’); AIS admission A (‘yes’,’no’); (AIS admission E was set as the reference level for AIS admission variable and is part of the intercept) (final n = 93) | ||||
---|---|---|---|---|
LOOCV: average observed accuracy = 0.688; average kappa statistic = 0.362 | ||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value |
Intercept | = –1.883 | 352.4 | –0.005 | 0.996 |
Average MAP () | = –0.206 | 4.713 | –0.044 | 0.965 |
Average MAP () | = –8.064 | 7.643 | –1.055 | 0.291 |
Average HR () | = –0.0002 | 0.0649 | 0.004 | 0.997 |
Length of surgery () | = 0.0018 | 0.0054 | 0.336 | 0.737 |
Days to AIS discharge () | = 0.076 | 0.0613 | 1.240 | 0.215 |
Age () | = –0.0047 | 0.051 | –0.921 | 0.357 |
AIS admission D () | = 1.727 | 3.524 | 0.005 | 0.996 |
AIS admission C () | = 3.557 | 5.782 | 0.005 | 0.996 |
AIS admission B () | = 1.738 | 3.524 | 0.005 | 0.995 |
AIS admission A () | = 1.686 | 3.524 | 0.005 | 0.996 |
Model: , where time of MAP outside range 76–104 mmHg (n = 103 patients) | ||||
---|---|---|---|---|
LOOCV: average observed accuracy = 0.61; average kappa statistic = 0.158 | ||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value |
Intercept | = 0.368 | 0.333 | 1.103 | 0.269 |
Time MAP out 76–104 () | = –0.006 | 0.0026 | –2.566 | 0.0103* |
*p < 0.05.
Model: , where time of MAP outside range 76–117 mmHg (n = 103 patients) | ||||
---|---|---|---|---|
LOOCV: average observed accuracy = 0.5728; average kappa statistic = 0.102 | ||||
Predictor | Coef. estimate (logit) | Std. error | z-Value | p-Value |
Intercept | = 0.2881 | 0.287 | 1.002 | 0.316 |
Time MAP out 76–117 () | = –0.00788 | 0.0027 | –2.828 | 0.00468** |
**p < 0.01.
Model predicting AIS improvement: Model predicting AIS A: Model predicting AIS D: where average MAP; : AIS admission A (‘yes’, ‘no’); : AIS admission B (‘yes’, ‘no’); : AIS admission C (‘yes’, ‘no’); : AIS admission D (‘yes’, ‘no’); : NLI non-cervical; : Time MAP out 76–117; : Length of surgery; : Age; (AIS admission E and NLI cervical were set as the reference levels for the corresponding variable and are part of the intercept). All metrics are on LOOCV prediction (n = 93) | |||
---|---|---|---|
Model AIS improv. | Model AIS A | Model AIS D | |
Predictor | Coef. estimate (logit) | Coef. estimate (logit) | Coef. estimate (logit) |
Intercept | = –16.24 | = 20.466 | = 1.558 |
Average MAP () | = 7.374 | = 27.031 | |
Average MAP (Cohn et al., 2010) () | = –8.215 | = –17.138 | |
AIS admission A () | = 15.54 | = –22.814 | = 2.324 |
AIS admission B () | = 16.1818 | = –20.38 | = 0.41 |
AIS admission C () | = 16.752 | = –19.01 | = –2.591 |
AIS admission D () | = 14.828 | = 0.217 | = –2.624 |
NLI non-Cervical () | = –1.228 | ||
Time MAP out 76–117 () | = 0.017 | ||
Length of Surgery () | = –0.0044 | ||
Age () | = 0.03 | ||
Model performance metric | Metric value | Metric value | Metric value |
Accuracy (95% CI) | 0.73 (0.629, 0.818) | 0.82 (0.735, 0.898) | 0.806 (0.71, 0.881) |
AUC | 0.743 | 0.88 | 0.87 |
Kappa | 0.45 | 0.629 | 0.573 |
Sensitivity | 0.71 | 0.812 | 0.793 |
Specificity | 0.74 | 0.836 | 0.812 |
Positive predicted value | 0.658 | 0.72 | 0.657 |
Negative predicted value | 0.788 | 0.89 | 0.896 |
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