Plasma Levels, Temporal Trends and Clinical Associations between Biomarkers of Inflammation and Vascular Homeostasis after Pediatric Traumatic Brain Injury

Expression of inflammatory (interleukin-6 [IL-6]) and vascular homeostatic (angiopoietin-2 [AP-2], endothelin-1 [ET-1], endocan-2 [EC-2]) biomarkers in pediatric traumatic brain injury (TBI) was examined in this prospective, observational cohort study of 28 children hospitalized with mild, moderate, and severe TBI by clinical measures (age, sex, Glasgow Coma Scale score [GCS], Injury Severity Score [ISS], and cerebral autoregulation status). Biomarker patterns suggest an inverse relationship between GCS and AP-2, GCS and IL-6, ISS and ET-1, but a direct relationship between GCS and ET-1 and ISS and AP-2. Biomarker patterns suggest an inverse relationship between AP-2 and ET-1, AP-2 and EC-2, but a direct relationship between AP-2 and IL-6, IL-6 and EC-2, and IL-6 and ET-1. Plasma concentrations of inflammatory and vascular homeostatic biomarkers suggest a role for inflammation and disruption of vascular homeostasis during the first 10 days across the severity spectrum of pediatric TBI. Although not statistically significant, without impact on cerebral autoregulation, biomarker patterns suggest a relationship between inflammation and alterations in vascular homeostasis. The large variation in biomarker levels within TBI severity and age groups, and by sex suggests other contributory factors to biomarker expression.

Early cardiovascular function and associated hemodynamics in adults with isolated moderate-severe traumatic brain injury: A pilot study

BACKGROUND

While cardiac dysfunction has been described following traumatic brain injury (TBI), its association with systemic and cerebral hemodynamics is not known. We examined the contemporaneous relationship between early cardiac function with systemic and cerebral hemodynamic parameters after moderate-severe TBI.

METHODS

Bedside transthoracic echocardiography (TTE) and transcranial Doppler (TCD) ultrasonography were performed within 24 h in patients > 18 years with isolated moderate-severe TBI. Systemic hemodynamic parameters were quantified using routine monitoring [heart rate and mean arterial pressures (MAP)] and calculation from echocardiographic data [stroke volume index (SVI), cardiac index (CI), and systemic vascular resistance index (SVRI)]. Systolic dysfunction was defined using TTE as global longitudinal strain (GLS) > -16%. Mean middle cerebral artery velocity (FVm) was the measure of cerebral hemodynamics and quantified using TCD.

RESULTS

Among 15 patients [mean age 43 ± 13 years, GCS 5 ± 3, 73% male], 15 TTE and 15 TCD exams were performed simultaneously. Five (33%) patients had systolic dysfunction, with significantly worse GLS (median [IQR] -12.1% [-14.1, -12] vs. -19.1% [-19.9, -17.7], p = 0.004). Median (IQR) MAP was 97 (89, 107) mmHg, SVI (29.0 [20.5, 31.0] mL m^-2), and CI (2.83 [2.05, 3.10] L/min m^-2) were low to normal, while SVRI (2704 dyne sec/cm⁵ m^-2 [2210, 4084]) was normal to high. None of the patients had abnormal TCDs. Higher GLS (reduced systolic function) was associated with lower SVI (r² = 0.274, p = 0.03) but not other parameters.

CONCLUSION

Systemic hemodynamic parameters were consistent with an early catecholamine-excess state. While reduced systolic function was associated with lower SVI, there was no relationship with reduced cerebral perfusion, possibly due to normal MAP.

Agreement Between Arterial Carbon Dioxide Levels With End-Tidal Carbon Dioxide Levels and Associated Factors in Children Hospitalized With Traumatic Brain Injury

IMPORTANCE

Alterations in the partial pressure of carbon dioxide, arterial (Paco2) can affect cerebral perfusion after traumatic brain injury. End-tidal carbon dioxide (EtCO2) monitoring is a noninvasive tool used to estimate Paco2 values.

OBJECTIVE

To examine the agreement between Paco2 and EtCO2 and associated factors in children with traumatic brain injury.

DESIGN, SETTING, AND PARTICIPANTS

A secondary analysis was conducted using data from a prospective cohort study of 137 patients younger than 18 years with traumatic brain injury who were admitted to the pediatric intensive care unit of a level I trauma center between May 1, 2011, and July 31, 2017. Analysis was performed from December 17, 2018, to January 10, 2019.

MAIN OUTCOMES AND MEASURES

The closest EtCO2 value obtained within 30 minutes of a Paco2 value and the closest systolic blood pressure value obtained within 60 minutes prior to a Paco2 value during the first 24 hours after admission were recorded. The main outcome of Paco2-EtCO2 agreement was defined as Paco2 between 0 and 5 mm Hg greater than the paired EtCO2 value, and it was determined using Bland-Altman analysis, Passing and Bablok regression, and the Pearson correlation coefficient. Multivariable regression models determined which factors were associated with agreement.

RESULTS

The analysis included 137 patients (34 girls and 103 boys; mean [SD] age, 10.0 [6.3] years) and 445 paired Paco2-EtCO2 data points. On average, Paco2 was 2.7 mm Hg (95% limits of agreement, -11.3 to 16.7) higher than EtCO2. Overall, 187 of all Paco2-EtCO2 pairs (42.0%) agreed. There was larger variation in the Paco2-EtCO2 difference during the first 8 hours compared with 9 to 24 hours after admission to the pediatric intensive care unit. Development of pediatric acute respiratory distress syndrome within 24 hours of admission was associated with a lower likelihood of Paco2-EtCO2 agreement (adjusted odds ratio, 0.20; 95% CI, 0.08-0.51) compared with no development of pediatric acute respiratory distress syndrome. A diagnosis of pediatric acute respiratory distress syndrome 1 to 7 days after admission was associated with a larger first-day Paco2-EtCO2 difference compared with those who never developed pediatric acute respiratory distress syndrome (mean [SD] difference, 4.48 [3.70] vs 0.46 [5.50] mm Hg).

CONCLUSIONS AND RELEVANCE

In this study of pediatric traumatic brain injury, Paco2-EtCO2 agreement was low, especially among patients with pediatric acute respiratory distress syndrome. Low Paco2-EtCO2 agreement early in hospitalization may be associated with future development of pediatric acute respiratory distress syndrome. Data on EtCO2 should not be substituted for data on Paco2 during the first 24 hours.

External Ventricular Drain Management Practices in Thailand: Results of the EPRACT Study

OBJECTIVE

We explored the external ventricular drain (EVD) practices in Thailand.

METHODS

We performed a survey-based study to describe EVD insertion, maintenance, quality improvement (QI) practices, and incidence of EVD infection.

RESULTS

The study included 58 of 101 hospitals contacted (57.4% response rate), with ≥600 beds (44.8%) and dedicated neurocritical care units (53%). The reasons for EVD placement included aneurysmal subarachnoid hemorrhage, traumatic brain injury, and ventriculoperitoneal shunt malfunction or infection; 75.9% of the hospitals cared for ≤100 EVDs annually. In Thailand, nonantimicrobial EVD catheters (98.3%) were used most often. Most hospitals (56.9%) did not routinely sample the cerebrospinal fluid. Prophylactic daily antibiotic use was prevalent (62.1%). Most hospitals (77.6%) did not measure the intracranial pressure during intrahospital transport. EVD infection was a commonly (69%) tracked QI measure; however, up to one third of the hospitals did not track any EVD QI measure. Most hospitals (94.8%) had no written EVD insertion and maintenance protocols. Most hospitals (79.3%) reported an EVD infection rate of ≤5% in the previous year. The low EVD infection rate, high cost, and/or the lack of equipment could account for the low usage of antimicrobial catheters and intracranial pressure monitoring.

CONCLUSIONS

The results of the present study have identified QI opportunities in EVD management in Thailand. The development of an EVD-related QI process, reliable tracking of EVD infection rates, adaptation of U.S. guidelines to create standardized EVD protocols, and examination of the association between EVD practices and clinical outcomes in low-to middle-income countries are urgently needed.

Patient characteristics and critical care workflow affect paging frequency in neurocritical care

Indicator of response urgency (page tag), paging domains, distribution of pages by time of the day, and factors associated with neurocritical care paging remain elusive and were examined in this study. We examined the association between patient, neurocritical care workflow characteristics, and paging domains on frequency of paging using Student's t-test, Chi-square test, and analysis of covariance. A total of 1852 patients generated 36,472 pages. The most common page tagging was "for your information" (n = 15067, 41.3%), while 2.8% (n = 1006) pages were tagged urgent. Paging was most frequent for cardiovascular (12.2%), pain, agitation, distress (6.9%) and sodium (5.3%) concerns. Paging frequency was highest for mechanically ventilated patients (p < 0.001), those with indwelling intracranial pressure monitor (p < 0.04), arterial catheter (p < 0.001), central venous access catheter (p < 0.001), and in those with lower Glasgow Coma Score (p < 0.001). Patients admitted between 18:00-06:00 (aOR 1.47, 95% CI 1.16-1.86) and 14:30-18:00 (aOR 1.46, 95% CI 1.14-1.86), and sodium (aOR 1.52, 95% CI 1.39-1.66), and cardiovascular concerns (aOR 1.24, 95% CI 1.15-1.32) were associated with higher night time paging frequency. Incorporating paging domains in daily workflow and their impact on outcome of paging on escalation of clinical care and patient outcomes warrants further examination.

Blood Pressure Thresholds and Mortality in Pediatric Traumatic Brain Injury

BACKGROUND

Hypotension after pediatric traumatic brain injury (TBI) is associated with poor outcomes, but definitions of low systolic blood pressure (SBP) vary. Age- and sex-specific, percentile-based definitions of hypotension may help to better identify children at risk for poor outcomes compared with traditional thresholds recommended in pediatric trauma care.

METHODS

Using the National Trauma Data Bank between 2007 and 2014, we conducted a retrospective cohort study of children with isolated severe TBI. We classified admission SBP into 5 percentile categories according to population-based values: (1) SBP less than the fifth percentile, (2) SBP in the fifth to 24th percentile, (3) SBP in the 25th to 74th percentile, (4) SBP in the 75th to 94th percentile, and (5) SBP ≥95th percentile. These definitions were compared with the American College of Surgeons (ACS) hypotension definition. The association between SBP percentiles and in-hospital mortality was analyzed by using multivariable Poisson regression models.

RESULTS

There were 10 473 children with severe TBI included in this study. There were 2388 (22.8%) patients who died while in the hospital. Compared with SBP in the 75th to 94th percentile, mortality was higher with SBP less than the fifth percentile (relative risk [RR] 3.2; 95% confidence interval [CI] 2.9-3.6), SBP in the fifth to 24th percentile (RR 2.3; 95% CI 2.0-2.7), and SBP in the 25th to 74th percentile (RR 1.4; 95% CI 1.2-1.6). An increased risk of mortality with SBP <75th percentile was present across all age subgroups. SBP targets using the ACS hypotension definition were higher than the fifth percentile hypotension definition, but were lower than the 75th percentile hypotension definition.

CONCLUSIONS

Admission SBP <75th percentile was associated with a higher risk of in-hospital mortality after isolated severe TBI in children. SBP targets based on the 75th percentile were higher compared with traditional ACS targets. Percentile-based SBP targets should be considered in defining hypotension in pediatric TBI.

Association of Early Myocardial Workload and Mortality Following Severe Traumatic Brain Injury

OBJECTIVES

To examine the impact of early myocardial workload on in-hospital mortality following isolated severe traumatic brain injury.

DESIGN

Retrospective cohort study.

SETTING

Data from the National Trauma Databank, a multicenter trauma registry operated by the American College of Surgeons, from 2007 to 2014.

PATIENTS

Adult patients with isolated severe traumatic brain injury (defined as admission Glasgow Coma Scale < 8 and head Abbreviated Injury Score ≥ 4).

INTERVENTIONS

Admission rate-pressure product, categorized into five levels based on published low, normal, and submaximal human thresholds: less than 5,000; 5,000-9,999; 10,000-14,999; 15,000-19,999; and greater than 20,000.

MEASUREMENTS AND MAIN RESULTS

Data from 26,412 patients were analyzed. Most patients had a normal rate-pressure product (43%), 35% had elevated rate-pressure product, and 22% had depressed rate-pressure product at hospital admission. Compared with the normal rate-pressure product group, in-hospital mortality was 22 percentage points higher in the lowest rate-pressure product group (cumulative mortality, 50.2%; 95% CI, 43.6-56.9%) and 11 percentage points higher in the highest rate-pressure product group (cumulative mortality, 39.2%; 95% CI, 37.4-40.9%). The lowest rate-pressure product group was associated with a 50% increased risk of mortality, compared with the normal rate-pressure product group (adjusted relative risk, 1.50; 95% CI, 1.31-1.76%; p < 0.0001), and the highest rate-pressure product group was associated with a 25% increased risk of mortality, compared with the normal rate-pressure product group (adjusted relative risk, 1.25; 95% CI, 1.18-1.92%; p < 0.0001). This relationship was blunted with increasing age. Among patients with normotension, those with depressed and elevated rate-pressure products experienced increased mortality.

CONCLUSIONS

Adults with severe traumatic brain injury experience heterogeneous myocardial workload profiles that have a "U-shaped" relationship with mortality, even in the presence of a normal blood pressure. Our findings are novel and suggest that cardiac performance is important following severe traumatic brain injury.

Differences in blood pressure by measurement technique in neurocritically ill patients: A technological assessment

Blood pressure data may vary by measurement technique. We performed a technological assessment of differences in blood pressure measurement between non-invasive blood pressure (NIBP) and invasive arterial blood pressure (ABP) in neurocritically ill patients. After IRB approval, a prospective observational study was performed to study differences in systolic blood pressure (SBP), mean arterial pressure (MAP), and cerebral perfusion pressure (CPP) values measured by NIBP arm, ABP at level of the phlebostatic axis (ABP heart) and ABP at level of the external auditory meatus (ABP brain) at 30 and 45-degree head of bed elevation (HOB) using repeated measure analysis of covariance and correlation coefficients. Overall, 168 patients were studied with median age of 57 ± 15 years, were mostly female (57%), with body mass index ≤30 (66%). Twenty-three percent (n = 39) had indwelling intracranial pressure monitors, and 19.7% (n = 33) received vasoactive agents. ABP heart overestimated ABP brain for SBP (11.5 ± 2.7 mmHg, p < .001), MAP (mean difference 13.3 ± 0.5 mmHg, p < .001) and CPP (13.4 ± 3.2 mmHg, p < .001). ABP heart overestimated NIBP arm for SBP (8 ± 1.5 mmHg, p < .001), MAP (mean difference 8.6 ± 0.8 mmHg, p < .001), and CPP (mean difference 9.8 ± 3.2 mmHg, p < .001). Regardless of HOB elevation, ABP heart overestimates MAP compared to ABP brain and NIBP arm. Using ABP heart data overestimates CPP and may be responsible for not achieving SBP, MAP or CPP targets aimed at the brain.

Risks of Routinely Clamping External Ventricular Drains for Intrahospital Transport in Neurocritically Ill Cerebrovascular Patients

BACKGROUND

Current guidelines recommend routine clamping of external ventricular drains (EVD) for intrahospital transport (IHT). The aim of this project was to describe intracranial hemodynamic complications associated with routine EVD clamping for IHT in neurocritically ill cerebrovascular patients.

METHODS

We conducted a retrospective review of cerebrovascular adult patients with indwelling EVD admitted to the neurocritical care unit (NICU) during the months of September to December 2015 at a tertiary care center. All IHTs from the NICU of the included patients were examined. Main outcomes were incidence and risk factors for an alteration in intracranial pressure (ICP) and cerebral perfusion pressure after IHT.

RESULTS

Nineteen cerebrovascular patients underwent 178 IHTs (79.8 % diagnostic and 20.2 % therapeutic) with clamped EVD. Twenty-one IHTs (11.8 %) were associated with post-IHT ICP ≥ 20 mmHg, and 33 IHTs (18.5 %) were associated with escalation of ICP category. Forty IHTs (26.7 %) in patients with open EVD status in the NICU prior to IHT were associated with IHT complications, whereas no IHT complications occurred in IHTs with clamped EVD status in the NICU. Risk factors for post-IHT ICP ≥ 20 mmHg were IHT for therapeutic procedures (adjusted relative risk [aRR] 5.82; 95 % CI, 1.76-19.19), pre-IHT ICP 15-19 mmHg (aRR 3.40; 95 % CI, 1.08-10.76), pre-IHT ICP ≥ 20 mmHg (aRR 12.94; 95 % CI, 4.08-41.01), and each 1 mL of hourly cerebrospinal fluid (CSF) drained prior to IHT (aRR 1.11; 95 % CI, 1.01-1.23).

CONCLUSIONS

Routine clamping of EVD for IHT in cerebrovascular patients is associated with post-IHT ICP complications. Pre-IHT ICP ≥ 15 mmHg, increasing hourly CSF output, and IHT for therapeutic procedures are risk factors.

Characterizing the relationship between systemic inflammatory response syndrome and early cardiac dysfunction in traumatic brain injury

Systolic dysfunction was recently described following traumatic brain injury (TBI), and systemic inflammation may be a contributing mechanism. Our aims were to 1) examine the association between the early systemic inflammatory response syndrome (SIRS) and systolic cardiac dysfunction following TBI, and 2) describe the longitudinal change in SIRS criteria, cardiac function, and hemodynamic parameters during the first week of hospitalization. We used a secondary analysis of a prospective cohort study examining cardiac function (with transthoracic echocardiography on the first day and serially over the first week of hospitalization) in 32 moderate-severe isolated TBI patients, and quantified the admission and daily SIRS response to injury. We determined the association of admission SIRS and systolic dysfunction following TBI. Admission SIRS was present in 7 (21%) patients and was associated with systolic dysfunction on multivariable analysis (relative risk 4.01; 95% 1.16-13.79, p = .028). Both SIRS criteria and systolic cardiac function improved over the first week of hospitalization. In conclusion, early SIRS is common among patients with moderate-severe TBI, and the presence of SIRS criteria on admission is associated with systolic cardiac dysfunction following TBI.

Spurious hypoxemia

OBJECTIVE

To discuss the pathophysiology and clinical implications of spurious hypoxemia in the setting of hyperleukocytosis.

DESIGN

Case report and review of the literature.

SETTING

A 22-bed, adult neurosciences critical care unit at a tertiary care hospital.

PATIENT

A 49-yr-old male with chronic myelogenous leukemia.

INTERVENTIONS

Administration of hydroxyurea and imatinib mesylate.

MEASUREMENTS AND MAIN RESULTS

The patient was admitted to the neurosciences critical care unit with an acute nontraumatic subdural hematoma that required emergent surgical evacuation. His clinical course was notable for neurologic deterioration, sepsis, hyperleukocytosis, severe hypoxemia, and prolonged mechanical ventilation. An inverse relationship was observed between arterial oxygen tension and the magnitude of hyperleukocytosis. Hypoxemia resolved after the institution of chemotherapy and normalization of white cell count. Pulse oximeter saturation was normal throughout.

CONCLUSIONS

Patients with hyperleukocytosis are at risk for severe hypoxemia, which may be real or spurious. Failure to recognize spurious hypoxemia can lead to unnecessary diagnostic tests and therapeutic interventions, exposing patients to avoidable risk. A diagnostic algorithm is proposed.