Keywords
neurocritical care - neuroanesthesia - stroke - traumatic brain injury
Awake Craniotomy versus General Anesthesia in Brain Cancer Progression
Awake Craniotomy versus General Anesthesia in Brain Cancer Progression
High-grade gliomas (World Health Organization [WHO] grade III and IV) are associated
with poor prognosis owing to rapid progression and recurrence. Previous studies in
non-neurological malignancies have explored the association between the type of anesthesia
and outcomes.[1]
[2] However, there is minimal literature on the type of anesthesia and brain cancer
progression. In a multicenter retrospective study by Chowdhury et al, they compared
the effect of awake craniotomy (AC) versus general anesthesia (GA) on progression-free
survival (PFS) and overall survival (OS) in patients with high-grade gliomas undergoing
surgical resection.[3] A total of 891 patients across five centers were included. The two groups were similar
with respect to age, sex, location of the tumor, and preoperative Karnofsky Performance
Status. However, the GA group had more patients with grade IV tumors and larger tumor
size compared to the AC group. Regarding the outcomes, the median PFS in the AC group
was 0.54 (95% confidence interval [CI]: 0.45–0.65) years compared with 0.53 years
(95% CI: 0.48–0.60) in the GA group; hazard ratio (HR) 1.05; p = 0.553. The OS was greater in the AC group compared to GA [median survival of 1.7
(95% CI: 1.30–2.32) versus 1.25 (95% CI: 1.15–1.37) years; HR: 0.76; p < 0.009]. However, multivariable analyses did not show a significant difference for
PFS or OS after controlling for other variables of interest. The median length of
hospital stay was significantly shorter in the AC group (2 [ interquartile range,
IQR: 3] vs. 5 [ IQR: 5] days in the GA [p < 0.001]). Though this study suffered from inherent limitations of retrospective
study, this is the first large series study on this topic and future prospective randomized
controlled trials (RCTs) are needed to study the effect of the different anesthetic
techniques in glioma progression.
Asleep-Awake-Asleep Technique and Monitored Anesthesia Care for Awake Craniotomy
Asleep-Awake-Asleep Technique and Monitored Anesthesia Care for Awake Craniotomy
AC is often indicated for the resection of pathology close to eloquent areas of the
brain. Two commonly used anesthesia techniques are asleep-awake-asleep (SAS) and monitored
anesthesia care (MAC). However, there is very limited evidence comparing these two
commonly used anesthesia techniques in terms of safety and efficacy. Natalini et al
conducted a systematic review and meta-analysis to compare SAS and MAC techniques
during AC.[4] The main outcome measures of their study included the incidences of AC failure,
perioperative nausea and vomiting, intraoperative seizures, intraoperative respiratory
adverse events, and the hospital length of stay (LOS). Eighteen studies were included
(4 RCTs, 4 prospective observational studies, 5 retrospective studies, and 5 case
series). Among the 11 studies that adopted MAC, dexmedetomidine was the first-line
sedative, either alone or in combination with propofol or remifentanil. On the other
hand, propofol/remifentanil combination was the most frequently used regimen during
the SAS technique. There was moderate and substantial heterogeneity in the MAC and
SAS groups (I2
was 49 and 81%, respectively). The pooled proportions of AC failure in the MAC and
SAS subgroups were 1 (95% CI: 0–3) and 5% (95% CI: 1–10), respectively. They concluded
that MAC was associated with a lower AC failure rate, shorter procedure time, and
a (not statistically significant) trend toward reduced LOS and incidence of nausea
and vomiting compared with SAS. The main limitations of the study were a high risk
of bias due to the inclusion of retrospective studies and a single large study that
influenced the result of higher AC failure. However, further RCTs are recommended
to directly compare the two techniques.
Enhanced Recovery after Elective Craniotomy
Enhanced Recovery after Elective Craniotomy
Enhanced recovery after surgery (ERAS) protocols have proven benefits in outcomes
in various surgical subspecialties.[5]
[6] However, the literature about its implementation and benefits in neurosurgical patients
is sparse. Wang et al conducted an RCT to evaluate the clinical effectiveness and
safety of ERAS protocols compared to the usual care in patients undergoing elective
craniotomy for a single intracranial lesion.[7] A total of 151 patients were randomized into ERAS (76 patients) and control (75
patients) groups. Their self-formulated ERAS protocol was based on existing literature
and it was compliant with the ERAS society reporting guidelines. Patient demographics
and surgical characteristics were comparable between the groups. The main findings
of the study include the reduced LOS in the hospital (3 vs. 4 days, [95% CI: 1–2],
p <0.0001), lower hospitalization costs (5880 USD vs. 6266 USD, [95% CI: 234.8–633.6],
p < 0.0001), and early ambulation (75.0 vs. 30.7%, odds ratio [OR]: 7.5, [95% CI: 3.6–15.8],
p <0.0001). They recommend the evaluation of the ERAS protocol in larger multicenter
studies.
Erector Spinae Plane Block in Lumbar Spine Surgery
Erector Spinae Plane Block in Lumbar Spine Surgery
Postoperative pain management after lumbar spine surgery can be challenging and inadequate
pain management can predispose patients to develop chronic post-surgical pain. Multimodal
analgesia regimens have been proposed and more recently, the use of regional anesthesia
techniques especially erector spinae plane block (ESPB) has been popular.[8]
[9] Oh et al published a systematic review and meta-analysis of the RCTs comparing the
efficacy of ESPB with either no block or sham block.[10] They included 12 studies and a total of 665 patients with 330 of them in the ESPB
group and 335 in the control group. ESPB significantly reduced opioid (intravenous
morphine milligram equivalents) consumption in the first 24 hours after surgery (mean
difference = − 14.55; 95% CI: –21.03 to −8.07; p < 0.0001; I2 99%) compared to the control group. However, this difference was not seen at 48 hours.
In addition, the ESPB group had less rescue analgesia, a longer time to need rescue
analgesia, less postoperative nausea and vomiting, shorter LOS, and higher overall
satisfaction scores compared to the control group. Heterogeneity was the major limitation
of the study due to wide variation in block techniques with different timings, positions,
approaches, vertebral levels, and variations in local anesthetics in type, concentration,
and volumes.
Pain Management after Transsphenoidal Pituitary Surgery
Pain Management after Transsphenoidal Pituitary Surgery
Transsphenoidal resection of pituitary adenomas (PAs) is a minimally invasive neurosurgical
procedure and postoperative pain in this subset of patients is not well studied. There
are contrary beliefs about the severity of pain ranging from modest to severe.[11] Nevertheless, opioids are the most used analgesics in this patient population and
in general nonsteroidal anti-inflammatory drugs (NSAIDs) are avoided in neurosurgical
patients. Guo et al conducted a randomized, single-center, noninferiority trial to
compare the efficacy and safety of NSAIDs with tramadol following transsphenoidal
surgery for PAs.[12] A total of 202 patients were assigned to either the NSAIDs group (n = 101) or the tramadol group (n = 101). The patients in the NSAIDs group were treated with intravenous parecoxib
sodium (40 mg) and oral loxoprofen sodium (60 mg). The tramadol group was treated
with intramuscular tramadol hydrochloride (100 mg) and oral tramadol hydrochloride
(100 mg). Both groups were similar in demographics, clinical characteristics, and
tumor imaging features. Intention-to-treat analysis was used to analyze the patient
data. The mean visual analog scale scores for the first 24, 48, and 72 hours were
significantly lower in the NSAIDs group. Nausea was observed in 39.6 and 61.4% of
the NSAIDs group and tramadol group respectively. Importantly, 4.0% in the NSAIDs
group and 15.8% in the tramadol group received rescue analgesics. In addition, none
of the patients had sellar hematomas based on magnetic resonance imaging done on the
second postoperative day. The study concluded that the NSAIDs were a better choice,
though exploring the better subtype of NSAIDs was suggested by the researchers.
Risk Factors for Postoperative Diabetes Insipidus in Transsphenoidal Surgery
Risk Factors for Postoperative Diabetes Insipidus in Transsphenoidal Surgery
Diabetes insipidus (DI) is one of the complications after transsphenoidal pituitary
surgery that could be transient or permanent. There is a wide variation in the clinical
and biochemical definition of DI resulting in a wide range of reported incidences
ranging from 2 to 54%. Nevertheless, its occurrence is associated with increased morbidity,
hospital readmissions, and mortality. Hence, it is plausible to find predictors of
DI for better patient care and outcomes.[13] Joshi et al published a retrospective study to identify the perioperative risk factors
that may predispose to DI after pituitary surgery.[14] They included 2,529 patients of which postoperative DI was observed in 10.7% of
patients (6.2% had transient DI and 4.5% had permanent DI). The DI occurrence was
highest in patients with craniopharyngiomas (46.3%) followed by pituitary apoplexy
(14.3%) and Rathke's cleft cysts (14.3%). They found that younger age, intraoperative
cerebrospinal fluid encounter, and postoperative hyponatremia increased the risk of
DI. Postoperative hyponatremia is believed to be due to intraoperative pituitary damage,
causing subsequent vasopressin release and osmotic dysregulation in the body, similar
to syndrome of inappropriate anti-diuretic hormone secretion (SIADH). Increasing tumor
diameter increased the risk of DI in patients with functional PAs but not in nonfunctional
PAs.
Risk Factors for Venous Air Embolism in the Semi-Sitting Position
Risk Factors for Venous Air Embolism in the Semi-Sitting Position
The semi-sitting position in neurosurgery has many advantages including better anatomical
orientation, less brain swelling with decreased need for mechanical retraction, and
better operative field with less bleeding. However, the risk of venous air embolism
(VAE) in this position is high. The reported incidence and the risk factors for VAE
vary in the literature and often from a small number of patient cohorts. In a retrospective
study, Al-Afif et al looked at the incidence and the risk factors for VAE in 740 patients
who underwent surgery in the semi-sitting position.[15] The incidence of VAE in their cohort was 16.1% (119/740 patients). VAE was apparent
on transthoracic doppler echocardiography or transesophageal echocardiography in all
cases. Decrease in end-tidal carbon dioxide (EtCO2) and blood pressure (BP) and a
reduction in both parameters were seen in 19, 15, and 19% of the patients, respectively.
Occurrence of VAE was most common during tumor resection (67%) followed by craniotomy
(24%) and wound closure (9%). The VAE was managed well in all the cases, except for
one where the surgery had to be aborted. Management strategies for VAE included flushing
of the surgical site with 0.9% normal saline, gentle compression of the jugular veins
by the anesthesiologist, Trendelenburg positioning, aspiration from the central line
(if present), and rapid treatment of hypotension by intravenous fluids and/or vasopressors.
Only two patients had VAE-related systemic or cerebral consequences (cerebral infarctions
with transient or permanent neurological deficits). No significant differences were
noted between patients with and without VAE regarding age, height, weight, body mass
index, preoperative hemoglobin concentration, a history of chronic cardiovascular
disorders, surgical approach, and type of tumor. The study could not identify any
perioperative risk factors for the occurrence of VAE. Therefore, the authors suggest
that the semi-sitting position is safe and its advantages outweigh the benefits due
to the lower incidence of VAE and lower complications secondary to VAE.
Management of Hyperglycemia in Patients with Intracranial Pathology
Management of Hyperglycemia in Patients with Intracranial Pathology
Current guidelines on optimal blood sugar management in patients with intracerebral
hemorrhage (ICH) remain unclear as there is still debate on the optimal glucose targets
for this patient population. Guidelines from the American Heart Association/American
Stroke Association state that serum glucose should be monitored and both hypoglycemia
and hyperglycemia should be avoided; however, no definite cuff-offs are provided.[16] Qureshi et al retrospectively evaluated the effect of persistent hyperglycemia on
outcomes in 1000 patients with ICH (within 4.5 hours of symptom onset).[17] The patients investigated were part of the ATACH-2 trial (Antihypertensive Treatment
of Acute Cerebral Hemorrhage II) in which patients with hyperglycemia (>185 mg/dL
and possibly > 140 mg/dL) were treated with insulin. Multivariate analysis, adjusted
for variables (Glasgow Coma Scale (GCS) score, hematoma volume, presence or absence
of intraventricular hemorrhage, hyperlipidemia, cigarette smoking, and hypertension)
showed that persistent hyperglycemia, either moderate (140 -180mg/dL) (OR: 1.8 [95%
CI: 1.1–2.8]) or severe (> 180mg/dL) (OR: 1.8 [95% CI: 1.2–2.7]), was associated with
increased risk of death or disability in nondiabetic patients with ICH. However, this
association was not seen in diabetic patients (p =0.996).
Similarly, Eagles et al performed a retrospective post-hoc analysis of data sets of
patients with subarachnoid hemorrhage (SAH) from the CONSCIOUS I Trial (Clazosentan
to overcome neurological ischemia and infarction occurring after SAH).[18] Three hundred ninety-nine patients with SAH were compared in this matched analysis
and propensity scores were used on covariates and outcomes of interest. It showed
that maintaining blood glucose (BG) levels below 9.2 mmol/L (<165 mg/dL) in SAH patients
was associated with a decreased risk for unfavorable outcomes (defined as a modified
Rankin Scale [mRS] grade > 2). However, there was no statistically significant decrease
in the risk of death.
Hyperglycemia during thrombolysis for acute ischemic stroke (AIS) has been associated
with worse functional outcomes and hemorrhagic complications.[19] However, whether hyperglycemia during an AIS worsens functional outcomes or is purely
a marker of insulin resistance or stress remains unclear. Previous research from 2019
did not show a significant difference in functional outcomes at 90 days between the
standard versus intensive glycemia treatment groups.[20] Recently, Torbey et al performed a subgroup analysis of the SHINE (Stroke Hyperglycemia
Insulin Network Effort) study.[21] In this study, authors did a subgroup analysis of patients with ischemic stroke
randomized to standard (target BG 80–179 mg/dL) versus intensive (target BG 80–130 mg/dL)
BG control for 72 hours. Subgroup analysis was based on various glycemic parameters:
acute BG level, absence versus presence of diagnosed and undiagnosed diabetes, hemoglobin
A1c (HbA1c), glycemic gap (baseline BG—expected average daily BG), stress hyperglycemia
ratio (baseline BG concentration/HbA1c), and BG variability. Their primary outcome
was a 90-day functional outcome, based on the 90-day mRS, adjusted for stroke severity.
Their study found no significant difference in the 90-day functional outcomes with
different glycemic parameters.
Mechanical thrombectomy (MT) in patients with AIS, due to a large artery occlusion,
is becoming the standard of care in patients who can be treated within 24 hours of
the time last known to be well. However, complications such as malignant cerebral
edema (MCE) and ICH can occur and are associated with poor neurological outcomes.
Cannarsa et al retrospectively analyzed 500 patients who underwent MT for anterior
cerebral circulation large vessel occlusions.[22] They found that elevated initial stress glucose ratios (iSGR = initial blood glucose/estimated
average glucose) significantly increased (OR: 14.26, [95% CI: 3.82–53.26], p < 0.001) the risk of MCE and ICH was an independent predictor of poor functional
outcome. However, whether stress hyperglycemia represents a modifiable risk factor
remains uncertain and further investigations are needed.
Optimal target values for BG after elective brain surgery also remain unclear. Postoperative
infection after brain surgery is a serious complication with complex pathophysiology
and hyperglycemia can be a factor that contributes to both infectious and noninfectious
complications.[23]
[24] Kulikov et al did a prospective single-center observational cohort study with 514
patients.[25] Severe intraoperative hyperglycemia ([BG] ≥180 mg/dL) was found to be associated
with a higher risk of infections within the first postoperative week in patients undergoing
elective brain neurosurgical procedures (OR: 3.71, [95% CI: 1.24–11.09], p = .018). Preoperative levels of HbA1c showed a reliable marker of risk for both severe
hyperglycemia and postoperative infection in these patients. However, until now it
is not known if more precise monitoring and tighter control of perioperative hyperglycemia
have an impact on the clinical outcome.
Revascularization in Carotid Artery Stenosis
Revascularization in Carotid Artery Stenosis
Carotid artery stenting (CAS) or carotid endarterectomy (CEA) is well-established
treatment options for patients with symptomatic carotid artery stenosis.[26] Whether CAS or CEA is a better revascularization choice for asymptomatic carotid
stenosis patients remains undetermined. Wang et al conducted a systematic review on
this topic (7,230 patients) and found that CAS has comparable perioperative and long-term
composite outcomes compared with CEA in patients with asymptomatic carotid artery
stenosis.[27] However, CAS may have a higher risk of any stroke and nondisabling stroke in the
perioperative period.
On a similar subject, the choice of anesthesia technique (local anesthesia [LA] versus
[GA]) for CEA is debatable. Rerkasem et al conducted a Cochrane review (16 RCTs) on
the topic of LA versus GA for CEA.[28] The review showed that there were no differences between LA and GA in the 30-day
incidence of stroke (OR: 0.91, [95% CI: 0.66–1.26]; p =0.58; low-quality evidence) and death (OR: 0.61, [95% CI: 0.35–1.06]; p =0.08; low-quality evidence).
Association of End-Tidal Carbon Dioxide and Blood Pressure with Perioperative Stroke
Association of End-Tidal Carbon Dioxide and Blood Pressure with Perioperative Stroke
Perioperative stroke leads to increased morbidity, mortality, and prolonged hospital
stay.[29] Although preexisting risk factors for perioperative stroke are well known, it is
important to find modifiable intraoperative risk factors for the prevention of perioperative
stroke.[30] In the pursuit of finding intraoperative risk factors, Vlisides et al conducted
a multicenter, retrospective, observational case–control study to find the relationship
between changes in intraoperative EtCO2, hypotension and perioperative ischemic stroke (within 30 days after surgery) in
adult patients scheduled for noncardiac, nonintracranial, and nonmajor vascular surgeries.[31] One of the physiologic basis of their study was that reduced cerebral blood flow
(due to hypotension) and carbon dioxide dysregulation can lead to watershed infarction
by hypoperfusion or impaired clearance of microemboli.[32] In this study, they included 122 patients with stroke and 496 matched (1:4) controls.
Regression modelling was used to find the relationship between stroke and physiologic
variables. The strongest association was noted for mean arterial pressure (MAP) less
than 55 mm Hg and EtCO2 30 mm Hg or less and 45 mm Hg or greater. However, no interaction effect was observed
between MAP and EtCO2 in relation to stroke. It was observed that 58% of the strokes occurred within the
first 3 postoperative days and it was most common in the middle cerebral artery territory.
Fifteen percent of stroke patients died in the hospital, and less than 30% of patients
could be discharged home in the 30-day period. The study concluded that intraoperative
hypotension and both hypo- and hypercarbia were independently associated with postoperative
ischemic stroke.
Effect of Anesthesia on Outcome after Endovascular Treatment for Acute Ischemic Stroke
Effect of Anesthesia on Outcome after Endovascular Treatment for Acute Ischemic Stroke
Endovascular treatment of AIS of large vessel occlusion has now become the standard
of care and it has been shown to reduce post-stroke disabilities. Albeit, there is
still a lot of controversy around the optimal type of anesthesia for patients undergoing
endovascular treatment.[33] Wagner et al conducted a retrospective matched comparison study of 1284 patients
(GA: n = 851, non-GA: n = 433) from eight stroke centers (Swiss Stroke Registry).[33] They showed a worse functional outcome (3-month mRS with an estimated coefficient
of 3.40 [1.76–5.04]), and dependency or death (OR: 1.49 [1.07–2.07]) after endovascular
treatment of anterior circulation stroke with GA compared to without GA and this finding
was independent of known patient differences. However, data analysis showed that the
reason for GA was not always known, as factors of agitation could also have played
a role in the decision making and the GA group had patients who had an intraoperative
conversion from conscious sedation (CS) to GA. Hence, it remains to be determined
whether a change in anesthesia technique would change the clinical outcome and if
a change in technique would be even feasible in some of these patients.
Maurice et al recently finished the General Anesthesia versus Sedation for Acute Stroke
Treatment (GASS) trial in France.[34] Their study investigated GA versus CS, both with hemodynamic control during intraarterial
treatment for stroke. Their single-blind randomized trial studied 351 patients and
found that the functional outcomes 3 months after endovascular treatment for stroke
were similar between GA and CS (relative risk: 0.91, [95% CI: 0.69–1.19], p = 0.474) and therefore, suggest that clinicians can use either approach. The incidence
of technical failure of endovascular therapy in the CS group was found to be greater,
while recanalization results were better in the GA group (144 of 169 [85%] vs. 131
of 174 [75%]; P= 0.021). Patients experienced more episodes of hyper- and hypotension
in the GA group, but the cumulative duration of hypotension was found to be the same
in both groups.
On a similar topic, Liang et al performed a RCT (CANVAS II trial—Choice of Anesthesia
for Endovascular Treatment of Acute Ischemic Stroke) in 87 patients with acute posterior
circulation stroke. They showed that CS is not better than GA for functional recovery
(mRS at 90 days) after endovascular treatment of posterior circulation AIS (48.8 vs.
54.5%; risk ratio 0.89; [95% CI: 0.58–1.38]; adjusted OR: 0.91; [95% CI: 0.37–2.22]).
In addition, the rate of successful reperfusion was higher with GA when compared to
CS (95.3 vs. 77.3%; adjusted OR 5.86; [95% CI: 1.16–29.53]).[35]
[36]
Blood Pressure Management after Endovascular Treatment for Acute Ischemic Stroke
Blood Pressure Management after Endovascular Treatment for Acute Ischemic Stroke
One of the big concerns in patients undergoing MT is BP management before and after
revascularization. Anadani et al did a post-hoc analysis of the BP-TARGET multicenter
trial (Blood Pressure Target in Acute Stroke to Reduce Hemorrhage After Endovascular
Therapy) to assess the association between BP changes after revascularization and
clinical outcome.[37] In the BP-TARGET trial, patients were randomized into intensive systolic blood pressure
(SBP) treatment (SBP target 100–129 mm Hg to be achieved within 1 hour of randomization)
or standard SBP treatment (SBP target 130–185 mm Hg) and they found that intensive
SBP targets did not result in lower radiographic intraparenchymal hemorrhage rates
at 24 to 36 hours compared to standard care BP targets.[38] In this post-hoc analysis, authors looked at the change of systolic blood pressure
(∆SBP) as end-of-procedure SBP minus mean SBP at different time intervals (15–60 minutes,
1–6 hours, and 6–24 hours post-procedure) and outcomes after successful MT. This study
showed that ∆SBP had a linear relationship with poor outcomes and the risk of poor
outcomes was higher with less reduction from the baseline SBP. Blood pressure management
is complex after successful reperfusion, as findings reinforce the potential beneficial
effect of rapidly lowering elevated SBP within the first few hours after reperfusion.
Potential deleterious effect of significant alteration of BP after successful reperfusion
is seen giving the U-shaped relationship with mortality.
Effect of Hyperoxia on Outcomes in Ventilated Patients with Aneurysmal Subarachnoid
Hemorrhage
Effect of Hyperoxia on Outcomes in Ventilated Patients with Aneurysmal Subarachnoid
Hemorrhage
The early goals of management of a patient with aneurysmal subarachnoid hemorrhage
(aSAH) include optimization of oxygenation and ventilation for favorable outcomes.
While hypoxia aggravates brain injury, hyperoxia could be deleterious as well. Available
evidence suggests that hyperoxia results in poor neurological outcomes, delayed cerebral
ischemia (DCI), and mortality in patients with aSAH.[39] However, the optimal oxygenation parameters in this patient population are unknown,
and various thresholds for hyperoxia have been proposed in studies on this topic.
Grensemann et al conducted a single-center, retrospective, study with an aim to identify
an optimum target range of arterial partial pressure of oxygen (PaO2) in mechanically ventilated patients with aSAH.[40] They included 282 patients with aSAH who were mechanically ventilated for at least
72 hours. Their outcome measures were 30-day mortality, a favorable outcome (Glasgow
Outcome Scale of 4 or 5), and DCI. To determine the optimal target range of PaO2,
the integral values of PaO2 (> 80, 100, 120, and 150 mm Hg) and the time-weighted
quartiles of PaO2 (62–78, 78–85, 85–93, and 93–228 mm Hg) were calculated from four
hourly blood gas analyses. All these calculations were done on day 1 (hyperacute phase),
up to day 3 (acute phase) and up to day 14 from admission. Patients with higher PaO2 integrals had higher OR for 30-day mortality. The 30-day mortality rate was lowest
(20%) between time-weighted PaO2 values between 78 and 85 mm Hg, while it was 28, 23, and 32%, respectively, for the
quartiles 62 to 78, 85 to 93, and 93 to 228 mm Hg. In addition, favorable outcomes
at 3 months were highest (53%) for 78 to 85 mm Hg and 32, 39, and 32%, respectively,
for 62 to 78, 85 to 93, and 93 to 228 mm Hg. No association was found between oxygenation
parameters and DCI. Thus, the authors conclude that hyperoxia is associated with poorer
outcomes in patients with aSAH. Additionally, they suggested 78 to 85 mm Hg as the
optimal target range for time-weighted PaO2. Further prospective studies were needed to confirm this finding.
Management of Traumatic Brain Injury
Management of Traumatic Brain Injury
Traumatic brain injury (TBI) is a major cause of global death and disability. Significant
research has been conducted on the effect of TBI on the brain; however, until recently
extracranial organ dysfunction following TBI was not yet investigated. Krishnamoorthy
et al published pilot data from the TRACK-TBI study and investigated the incidence
of myocardial injury (MI) after TBI.[41] High-sensitivity troponin, a sensitive marker of myocardial injury, was used to
determine the incidence of early MI. Their study showed that MI is common following
TBI, seen in 20% of the studied population, with a probable dose-response association
with TBI severity. In addition, the early timing of MI seemed to be associated with
poor 6-month clinical outcomes after moderate to severe TBI. On a similar topic, circulatory
shock can occur in patients with TBI. The risk factors and long-term functional neurological
outcomes associated with circulatory shock in this patient population are not well
understood. Toro et al conducted a retrospective analysis of the TRACK-TBI database
and showed that race, GCS in the emergency department, computed tomography Rotterdam
scores less than 3, and development of hypotension in the emergency department were
associated with developing circulatory shock and showed to be associated with poor
long-term functional outcome.[42]
In this same TRACK-TBI study population, Toro et al investigated the association of
vasopressor choice with clinical and functional outcomes following moderate-to-severe
TBI through a retrospective cohort study.[43] The study included 156 adult patients with moderate-to-severe TBI (defined as GCS
score < 13) admitted to the intensive care unit (ICU) and who received intravenous
vasopressors within 48 hours after ICU admission. Regression analysis with propensity
score matching showed the patients received either phenylephrine or norepinephrine
as first-line agents for BP support. The choice of vasopressor showed not to be associated
with improved clinical or functional outcomes.
The main goals in the management of patients with severe TBI include reducing intracranial
pressure (ICP), maintaining an adequate cerebral perfusion pressure, and improving
oxygen delivery to the brain. Ischemia of the brain is considered a major cause of
secondary brain injury. Rezoagli et al did a study on the association between arterial
PaO2 and fraction of inspired oxygen (FiO2) levels within the first week of TBI and
clinical outcomes. They performed a secondary analysis on two previously performed
multicenter, prospective observational cohort studies from Europe and Australia; Collaborative
European Neuro Trauma Effectiveness in Research in Traumatic Brain Injury (CENTER-TBI)
study, and Australia–Europe Neuro Trauma Effectiveness Research in Traumatic Brain
Injury (Oz ENTER-TBI) study.[44] In patients with TBI, exposure to high PaO2 or high FiO2 was shown to be independently
associated with 6-month mortality in the CENTER-TBI cohort, and it showed that the
severity of brain injury did not modulate this relationship. However, this finding
was not validated in the Oz ENTER-TBI cohort due to the smaller sample size. Though
this study does support the need for caution with liberal oxygen therapy in patients
with TBI, one must remember that this association may not apply to patients where
FiO2 and PaO2 are titrated to optimize brain tissue oxygen (PbtO2) levels.
On the topic of PbtO2 monitoring, a recent systematic review and meta-analysis looked
at the use of brain tissue oxygen-guided management and outcomes in patients with
TBI.[45] This study showed that combined PbtO2-guided management with standard ICP-based
management was not significantly associated with increased favorable neurological
outcomes but showed increased survival and reduced ICP. However, the level of evidence
for this meta-analysis was low and more research needs to be conducted.
Management of Thrombolysis in Acute Ischemic Stroke
Management of Thrombolysis in Acute Ischemic Stroke
Intravenous thrombolysis with alteplase is the currently approved therapy for patients
with AIS who present within 4.5 hours of symptom onset.[46] In recent years, there has been increased interest in tenecteplase, a modified version
of alteplase, due to its ease of administration, lower cost, and better outcomes when
compared to alteplase. A recent systematic review (6 RCTs) comparing alteplase and
tenecteplase for thrombolysis in patients with AIS has shown that tenecteplase appeared
to be a better thrombolytic agent for AIS when compared to alteplase.[46] In addition, Tsivgoulis et al conducted a propensity score-matched data set from
20 centers on this topic and came to the same conclusion.[47] In 2017, the Norwegian tenecteplase stroke trial (NOR-TEST) showed that 0.4 mg/kg
tenecteplase had an efficacy and safety profile similar to that of a standard dose
(0.9 mg/kg) of alteplase in AIS, albeit in a patient population with a high prevalence
of minor stroke.[48] However, Kvistad et al conducted the NOR-TEST 2 trial, a phase 3, randomized, open-label,
noninferiority trial in 11 hospitals with stroke units in Norway.[49] The trial was prematurely terminated because tenecteplase at a dose of 0.4 mg/kg
yielded worse functional outcomes compared with alteplase. Currently, it remains the
question if tenecteplase is better than alteplase. Future trials are needed to assess
a lower dose of tenecteplase versus alteplase in patients with moderate or severe
stroke.
Narrative Reviews of Interest
Narrative Reviews of Interest
Several excellent review papers focused on topics of particular interest to neuroanesthesiologists
were published over the last year. Anaesthesia published a special issue entitled perioperative and critical care management of
the brain—current evidence.[50] It covered a wide spectrum of clinically important topics including anesthesia for
MT, clinical application of point-of-care ultrasound, management of TBI, status epilepticus,
and many other. There have been two excellent reviews on idiopathic intracranial hypertension
(IIH). First, on the pathophysiology, diagnosis and treatment options and the second
is a systematic review of cerebrospinal fluid shunting pathways as a treatment of
IIH.[51]
[52] On a similar topic, Atchley et al have published an updated review on cerebrospinal
fluid dynamics.[53] Ma and Bebawy published an excellent narrative review on the physiological mechanisms
that underlie the burst-suppression pattern and the evidence for its clinical use
in various perioperative settings.[54] Chowdhury et al published a continuing professional development module on anesthetic
considerations and management of endovascular thrombectomy for patients with AIS.[55] There have been few focused reviews on BP and hemodynamic management in patients
with acute brain injuries. The first was on the current evidence, knowledge gaps,
and emerging concepts on BP management after SAH and ICH and the second was on BP
management in the first 24 hours after ischemic stroke.[56]
[57] The final one was on optimal hemodynamic parameters for brain-injured patients in
the clinical setting.[58] Other interesting reviews include opioid alternatives in spine surgery, the effects
of anesthesia on glioma progression and cardiac-cerebral coupling.[59]
[60]
[61] Finally, there are the recent clinical practice guidelines from the Society for
Neuroscience in Anesthesiology and Critical Care on Perioperative care of patients
undergoing major complex spinal instrumentation surgery, and the guideline from the
American Heart Association/American Stroke Association on the management of patients
with spontaneous intracerebral hemorrhage.[62]
[63]
