Analysis of high-frequency PbtO2 measures in traumatic brain injury: Insights into the treatment threshold

Ryan Hirschi, Gregory W.J. Hawryluk, Jessica L. Nielson, J. Russell Huie, Lara L. Zimmermann, Rajiv Saigal, Quan Ding, Adam R. Ferguson, Geoffrey Manley

Research output: Contribution to journalArticle

Abstract

OBJECTIVE Brain tissue hypoxia is common after traumatic brain injury (TBI). Technology now exists that can detect brain hypoxia and guide corrective therapy. Current guidelines for the management of severe TBI recommend maintaining partial pressure of brain tissue oxygen (PbtO2) > 15–20 mm Hg; however, uncertainty persists as to the optimal treatment threshold. The object of this study was to better inform the relationship between PbtO2 values and outcome for patients with TBI. METHODS PbtO2 measurements were prospectively and automatically collected every minute from consecutive patients admitted to the San Francisco General Hospital neurological ICU during a 6-year period. Mean PbtO2 values in TBI patients as well as the proportion of PbtO2 values below each of 75 thresholds between 0 mm Hg and 75 mm Hg over various epochs up to 30 days from the time of admission were analyzed. Patient outcomes were determined using the Glasgow Outcome Scale. The authors explored putative treatment thresholds by generating 675 separate receiver operating characteristic curves and 675 generalized linear models to examine each 1–mm Hg threshold for various epochs. RESULTS A total of 1,380,841 PbtO2 values were recorded in 190 TBI patients. A high proportion of PbtO2 measures were below 20 mm Hg irrespective of the examined epoch. Time below treatment thresholds was more strongly associated with outcome than mean PbtO2. A treatment window was suggested: a threshold of 19 mm Hg most robustly distinguished patients by outcome, especially from days 3–5; however, benefit was suggested from maintaining values at least as high as 33 mm Hg. CONCLUSIONS This analysis of high-frequency physiological data substantially informs the relationship between PbtO2 values and outcome. The results suggest a therapeutic window for PbtO2 in TBI patients along with minimum and preferred PbtO2 treatment thresholds, which may be examined in future studies. Traditional treatment thresholds that have the strongest association with outcome may not be optimal.

Original languageEnglish (US)
Pages (from-to)1216-1226
Number of pages11
JournalJournal of neurosurgery
Volume131
Issue number4
DOIs
StatePublished - Oct 2019

Fingerprint

Brain Hypoxia
Therapeutics
Glasgow Outcome Scale
San Francisco
Traumatic Brain Injury
Partial Pressure
ROC Curve
General Hospitals
Uncertainty
Linear Models
Guidelines
Oxygen
Technology
Brain

Keywords

  • Brain tissue oxygenation
  • Head injury
  • Licox
  • Outcome
  • PO
  • Threshold
  • Trauma
  • Traumatic brain injury
  • Treatment window

Cite this

Hirschi, R., Hawryluk, G. W. J., Nielson, J. L., Russell Huie, J., Zimmermann, L. L., Saigal, R., ... Manley, G. (2019). Analysis of high-frequency PbtO2 measures in traumatic brain injury: Insights into the treatment threshold. Journal of neurosurgery, 131(4), 1216-1226. https://doi.org/10.3171/2018.4.JNS172604

Analysis of high-frequency PbtO2 measures in traumatic brain injury : Insights into the treatment threshold. / Hirschi, Ryan; Hawryluk, Gregory W.J.; Nielson, Jessica L.; Russell Huie, J.; Zimmermann, Lara L.; Saigal, Rajiv; Ding, Quan; Ferguson, Adam R.; Manley, Geoffrey.

In: Journal of neurosurgery, Vol. 131, No. 4, 10.2019, p. 1216-1226.

Research output: Contribution to journalArticle

Hirschi, R, Hawryluk, GWJ, Nielson, JL, Russell Huie, J, Zimmermann, LL, Saigal, R, Ding, Q, Ferguson, AR & Manley, G 2019, 'Analysis of high-frequency PbtO2 measures in traumatic brain injury: Insights into the treatment threshold', Journal of neurosurgery, vol. 131, no. 4, pp. 1216-1226. https://doi.org/10.3171/2018.4.JNS172604
Hirschi, Ryan ; Hawryluk, Gregory W.J. ; Nielson, Jessica L. ; Russell Huie, J. ; Zimmermann, Lara L. ; Saigal, Rajiv ; Ding, Quan ; Ferguson, Adam R. ; Manley, Geoffrey. / Analysis of high-frequency PbtO2 measures in traumatic brain injury : Insights into the treatment threshold. In: Journal of neurosurgery. 2019 ; Vol. 131, No. 4. pp. 1216-1226.
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abstract = "OBJECTIVE Brain tissue hypoxia is common after traumatic brain injury (TBI). Technology now exists that can detect brain hypoxia and guide corrective therapy. Current guidelines for the management of severe TBI recommend maintaining partial pressure of brain tissue oxygen (PbtO2) > 15–20 mm Hg; however, uncertainty persists as to the optimal treatment threshold. The object of this study was to better inform the relationship between PbtO2 values and outcome for patients with TBI. METHODS PbtO2 measurements were prospectively and automatically collected every minute from consecutive patients admitted to the San Francisco General Hospital neurological ICU during a 6-year period. Mean PbtO2 values in TBI patients as well as the proportion of PbtO2 values below each of 75 thresholds between 0 mm Hg and 75 mm Hg over various epochs up to 30 days from the time of admission were analyzed. Patient outcomes were determined using the Glasgow Outcome Scale. The authors explored putative treatment thresholds by generating 675 separate receiver operating characteristic curves and 675 generalized linear models to examine each 1–mm Hg threshold for various epochs. RESULTS A total of 1,380,841 PbtO2 values were recorded in 190 TBI patients. A high proportion of PbtO2 measures were below 20 mm Hg irrespective of the examined epoch. Time below treatment thresholds was more strongly associated with outcome than mean PbtO2. A treatment window was suggested: a threshold of 19 mm Hg most robustly distinguished patients by outcome, especially from days 3–5; however, benefit was suggested from maintaining values at least as high as 33 mm Hg. CONCLUSIONS This analysis of high-frequency physiological data substantially informs the relationship between PbtO2 values and outcome. The results suggest a therapeutic window for PbtO2 in TBI patients along with minimum and preferred PbtO2 treatment thresholds, which may be examined in future studies. Traditional treatment thresholds that have the strongest association with outcome may not be optimal.",
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AU - Hirschi, Ryan

AU - Hawryluk, Gregory W.J.

AU - Nielson, Jessica L.

AU - Russell Huie, J.

AU - Zimmermann, Lara L.

AU - Saigal, Rajiv

AU - Ding, Quan

AU - Ferguson, Adam R.

AU - Manley, Geoffrey

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N2 - OBJECTIVE Brain tissue hypoxia is common after traumatic brain injury (TBI). Technology now exists that can detect brain hypoxia and guide corrective therapy. Current guidelines for the management of severe TBI recommend maintaining partial pressure of brain tissue oxygen (PbtO2) > 15–20 mm Hg; however, uncertainty persists as to the optimal treatment threshold. The object of this study was to better inform the relationship between PbtO2 values and outcome for patients with TBI. METHODS PbtO2 measurements were prospectively and automatically collected every minute from consecutive patients admitted to the San Francisco General Hospital neurological ICU during a 6-year period. Mean PbtO2 values in TBI patients as well as the proportion of PbtO2 values below each of 75 thresholds between 0 mm Hg and 75 mm Hg over various epochs up to 30 days from the time of admission were analyzed. Patient outcomes were determined using the Glasgow Outcome Scale. The authors explored putative treatment thresholds by generating 675 separate receiver operating characteristic curves and 675 generalized linear models to examine each 1–mm Hg threshold for various epochs. RESULTS A total of 1,380,841 PbtO2 values were recorded in 190 TBI patients. A high proportion of PbtO2 measures were below 20 mm Hg irrespective of the examined epoch. Time below treatment thresholds was more strongly associated with outcome than mean PbtO2. A treatment window was suggested: a threshold of 19 mm Hg most robustly distinguished patients by outcome, especially from days 3–5; however, benefit was suggested from maintaining values at least as high as 33 mm Hg. CONCLUSIONS This analysis of high-frequency physiological data substantially informs the relationship between PbtO2 values and outcome. The results suggest a therapeutic window for PbtO2 in TBI patients along with minimum and preferred PbtO2 treatment thresholds, which may be examined in future studies. Traditional treatment thresholds that have the strongest association with outcome may not be optimal.

AB - OBJECTIVE Brain tissue hypoxia is common after traumatic brain injury (TBI). Technology now exists that can detect brain hypoxia and guide corrective therapy. Current guidelines for the management of severe TBI recommend maintaining partial pressure of brain tissue oxygen (PbtO2) > 15–20 mm Hg; however, uncertainty persists as to the optimal treatment threshold. The object of this study was to better inform the relationship between PbtO2 values and outcome for patients with TBI. METHODS PbtO2 measurements were prospectively and automatically collected every minute from consecutive patients admitted to the San Francisco General Hospital neurological ICU during a 6-year period. Mean PbtO2 values in TBI patients as well as the proportion of PbtO2 values below each of 75 thresholds between 0 mm Hg and 75 mm Hg over various epochs up to 30 days from the time of admission were analyzed. Patient outcomes were determined using the Glasgow Outcome Scale. The authors explored putative treatment thresholds by generating 675 separate receiver operating characteristic curves and 675 generalized linear models to examine each 1–mm Hg threshold for various epochs. RESULTS A total of 1,380,841 PbtO2 values were recorded in 190 TBI patients. A high proportion of PbtO2 measures were below 20 mm Hg irrespective of the examined epoch. Time below treatment thresholds was more strongly associated with outcome than mean PbtO2. A treatment window was suggested: a threshold of 19 mm Hg most robustly distinguished patients by outcome, especially from days 3–5; however, benefit was suggested from maintaining values at least as high as 33 mm Hg. CONCLUSIONS This analysis of high-frequency physiological data substantially informs the relationship between PbtO2 values and outcome. The results suggest a therapeutic window for PbtO2 in TBI patients along with minimum and preferred PbtO2 treatment thresholds, which may be examined in future studies. Traditional treatment thresholds that have the strongest association with outcome may not be optimal.

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KW - Traumatic brain injury

KW - Treatment window

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