Role of Dexmedetomidine for Sedation in Neurocritical Care Patients: A Qualitative Systematic Review and Meta-analysis of Current Evidence

Association of Early Dexmedetomidine Utilization With Clinical and Functional Outcomes Following Moderate-Severe Traumatic Brain Injury: A Transforming Clinical Research and Knowledge in Traumatic Brain Injury Study

OBJECTIVE

To examine early sedation patterns, as well as the association of dexmedetomidine exposure, with clinical and functional outcomes among mechanically ventilated patients with moderate-severe traumatic brain injury (msTBI).

DESIGN

Retrospective cohort study with prospectively collected data.

SETTING

Eighteen Level-1 Trauma Centers, United States.

PATIENTS

Adult (age > 17) patients with msTBI (as defined by Glasgow Coma Scale < 13) who required mechanical ventilation from the Transforming Clinical Research and Knowledge in TBI (TRACK-TBI) study.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Using propensity-weighted models, we examined the association of early dexmedetomidine exposure (within the first 5 d of ICU admission) with the primary outcome of 6-month Glasgow Outcomes Scale Extended (GOS-E) and the following secondary outcomes: length of hospital stay, hospital mortality, 6-month Disability Rating Scale (DRS), and 6-month mortality. The study population included 352 subjects who required mechanical ventilation within 24 hours of admission. The initial sedative medication was propofol for 240 patients (68%), midazolam for 59 patients (17%), ketamine for 6 patients (2%), dexmedetomidine for 3 patients (1%), and 43 patients (12%) never received continuous sedation. Early dexmedetomidine was administered in 77 of the patients (22%), usually as a second-line agent. Compared with unexposed patients, early dexmedetomidine exposure was not associated with better 6-month GOS-E (weighted odds ratio [OR] = 1.48; 95% CI, 0.98-2.25). Early dexmedetomidine exposure was associated with lower DRS (weighted OR = -3.04; 95% CI, -5.88 to -0.21). In patients requiring ICP monitoring within the first 24 hours of admission, early dexmedetomidine exposure was associated with higher 6-month GOS-E score (OR 2.17; 95% CI, 1.24-3.80), lower DRS score (adjusted mean difference, -5.81; 95% CI, -9.38 to 2.25), and reduced length of hospital stay (hazard ratio = 1.50; 95% CI, 1.02-2.20).

CONCLUSION

Variation exists in early sedation choice among mechanically ventilated patients with msTBI. Early dexmedetomidine exposure was not associated with improved 6-month functional outcomes in the entire population, although may have clinical benefit in patients with indications for ICP monitoring.

Safety, Efficacy, and Clinical Outcomes of Dexmedetomidine for Sedation in Traumatic Brain Injury: A Scoping Review

Dexmedetomidine is a promising alternative sedative agent for moderate-severe Traumatic brain injury (TBI) patients. Although the data are limited, the posited benefits of dexmedetomidine in this population are a reduction in secondary brain injury compared with current standard sedative regimens. In this scoping review, we critically appraised the literature to examine the effects of dexmedetomidine in patients with moderate-severe TBI to examine the safety, efficacy, and cerebral and systemic physiological outcomes within this population. We sought to identify gaps in the literature and generate directions for future research. Two researchers and a librarian queried PubMed, Embase, Scopus, and APA PsycINFO databases. Of 920 studies imported for screening, 11 were identified for inclusion in the review. The primary outcomes in the included studied were cerebral physiology, systemic hemodynamics, sedation levels and delirium, and the presence of paroxysmal sympathetic hyperactivity. Dexmedetomidine dosing ranged from 0.2 to 1 ug/kg/h, with 3 studies using initial boluses of 0.8 to 1.0 ug/kg over 10 minutes. Dexmedetomidine used independently or as an adjunct seems to exhibit a similar hemodynamic safety profile compared with standard sedation regimens, albeit with transient episodes of bradycardia and hypotension, decrease episodes of agitation and may serve to alleviate symptoms of sympathetic hyperactivity. This scoping review suggests that dexmedetomidine is a safe and efficacious sedation strategy in patients with TBI. Given its rapid onset of action and anxiolytic properties, dexmedetomidine may serve as a feasible sedative for TBI patients.

Effect of Dexmedotomdine hydrochloride (Percedex®) on functional outcome of patients with moderate and severe traumatic brain injury

Traumatic brain injury (TBI) is considered among the leading causes of morbidity and mortality worldwide being associated with significant social and economic burden. The best sedative regimen in TBI patients is yet to be identified. This study was designed to determine the effects of dexmedotomdine hydrochloride (Percedex®, DEX) on functional outcome of patients with moderate and severe traumatic brain injury (TBI). This was a retrospective cohort study including patients with severe (3-8) and moderate (9-13) TBI referring to a level I trauma center. We studied two groups of patients, those receiving DEX or routine sedation regimen in neurointensive care unit (NICU). The main outcome measures were the Glasgow outcome scale extended (GOSE) at 3 and 6-month. We have also recorded ICU and hospital length of stay (LOS) and the tracheostomy rate. We included 138 patients in two study groups (each including 69). The baseline characteristics were comparable between groups. DEX was associated with lower LOS in hospital (p = 0.002) and NICU (p = 0.003). The GOSE was comparable between two study groups at 3 (p = 0.245) and 6-month (p = 0.497). Multivariate regression analysis revealed that after LOS of NICU and hospital stay adjustment, DEX group experienced significantly improved 6-month GOSE with the average improvement in score of 0.92 compared to the control group (p = 0.041). DEX administration in patients with moderate and severe TBI was associated with decreased NICU and hospital LOS and improved functional outcome at 6-month.

Retrospective evaluation of dexmedetomidine dosing in a cohort of neurologically injured obese critically ill patients

Background

Dexmedetomidine is used in neurocritical care units (NCCUs) due to the light, dose-dependent sedation, and anxiolysis provided. It is unknown how to dose dexmedetomidine in obese patients. The primary objective is to assess the ability to achieve the goal Richmond Agitation Sedation Scale (RASS) measurements in obese patients with a neurological injury who are solely on dexmedetomidine before and after an institutional dosing change from actual body weight (ABW) to adjusted body weight (AdjBW).

Methods

This study included patients admitted to the NCCU with a neurological condition, required dexmedetomidine for at least 8 h as a sole sedative, and weighed ≥120% of ideal body weight. Percentage of RASS measurements within the goal range (-1 to +1) during the first 48 h while on dexmedetomidine were compared between patients dosed on ABW and on AdjBW.

Results

Sixty-eight patients in the ABW cohort and 72 patients in the AdjBW cohort were included. There were no statistical differences between the two groups (ABW vs. AdjBW) in the percent of RASS measurements in the goal range (53.2% ± 34.8% vs. 55% ± 37%; P = 0.78), mean weight (99.2 ± 26 vs. 96.8 ± 20.9 kg; P = 0.55), or the average dose of dexmedetomidine required to achieve first goal RASS score (0.4 ± 0.3 vs. 0.4 ± 0.3 mcg/kg/h; P = 0.98).

Conclusions

Dosing dexmedetomidine using AdjBW in obese critically ill neurologically injured patients for ongoing sedation resulted in no statistical difference in the percent of RASS measurements within the goal when compared to ABW dosing. Further studies are warranted.

Effect of dexmedetomidine and propofol sedation on the prognosis of children with severe respiratory failure: a systematic review and meta-analysis

BACKGROUND

During treatment of acute respiratory failure (ARF) in children, sedation can reduce pain, improve tolerance, and reduce the incidence of adverse events, so selecting an appropriate sedation strategy is very important for improving prognosis and quality of life. Both dexmedetomidine and propofol have good sedative effects, so we investigated the application of these drugs in critically ill children with ARF by literature search and meta-analysis.

METHODS

We searched Embase, The Cochrane Library, PubMed, Ovid, Clinicaltrials.org, and Google Scholar for randomized controlled trials (RCTs) preferentially but not exclusively, and used RevMan 5.4 to analyze the screened literature.

RESULTS

Seven studies were included in the quantitative meta-analysis, with a total of 1,188 patients. There was no significant difference in the effect of dexmedetomidine and propofol on the duration of tracheal intubation in children with ARF [mean difference (MD) =-0.05; 95% confidence interval (CI): (-0.42, 0.32); Z=0.26; P=0.79], but dexmedetomidine sedation could reduce the intensive care unit (ICU) stay in children with ARF [MD =-0.62; 95% CI: (-1.08, -0.16); Z=2.65; P=0.008], and shorten the total hospital stay [MD =-1.94; 95% CI: (-2.63, -1.25); Z=5.48; P<0.00001]. There was no significant effect on mortality between the two groups [odds ratio (OR) =0.48; 95% CI: (0.19, 1.25); Z=1.50; P=0.13]. The incidence rate of bradycardia with dexmedetomidine sedation was higher than with propofol [OR =12.30; 95% CI: (2.28, 66.47); Z=2.92; P=0.004], and the incidence of hypotension was also higher [OR =6.99, 95% CI: (1.22, 39.86); Z=2.19; P=0.03].

DISCUSSION

Compared with propofol, dexmedetomidine can significantly reduce the ICU stay and hospital stay. However, bradycardia and hypotension may occur during the use of dexmedetomidine, which requires close attention and timely intervention.

Sedation in the Intensive Care Unit

Purpose of Review

This narrative review illustrates literature over the last 5 years relating to sedation delivery to mechanically ventilated adult patients in intensive care units.

Recent Findings

There has been an increase in dexmedetomidine-related publications but although systematic reviews suggest dexmedetomidine reduces delirium, agitation, and length of stay, clinical trials have not supported these findings. It is likely to be useful for the managing patients with persisting agitation. Guidelines continue to recommend lightly sedating patients but considerable variation remains in clinical practice and in research trials. Protocols with no sedative infusions and morphine boluses as needed are feasible and safe, while educational interventions can decrease sedation-related adverse events.

Summary

Research trials have mainly focused on individual drugs rather than practice. Given evidence is slow to translate into practice; work is needed to understand and respond to the concerns of clinicians regarding deep sedation and agitation.

Control of Hemodynamic Responses and Perioperative Outcomes in Transsphenoidal Pituitary Surgery: A Qualitative Systematic Review of the Available Evidence

Transnasal transsphenoidal (TNTS) pituitary surgery is associated with short-lived but intense nociceptive stimuli which cause substantial hemodynamic perturbations that may increase blood loss and impair visualization of the surgical field. This systematic review aimed to critically appraise the clinical evidence for the efficacy and safety of various anesthetic techniques, other pharmacological modalities, and supplementary interventions by assessing intraoperative systemic hemodynamics, use of adjunct medications, quality of the surgical field, intraoperative blood loss, and recovery profiles in patients undergoing TNTS pituitary surgery. Relevant randomized clinical trials and observational studies were identified in a systematic literature search; 16 studies (13 randomized clinical trials, 3 observational studies) enrolling a total of 907 patients were identified for inclusion in this review. Propofol provided more potent hemodynamic control compared with volatile anesthetics with a sparing effect on the need for additional drugs to blunt hemodynamic responses. Recovery profiles between propofol and sevoflurane were either equivalent or favored sevoflurane, but both agents were superior to isoflurane. Regarding intraoperative analgesia, remifentanil was associated with superior hemodynamic control and recovery profiles than fentanyl. Dexmedetomidine had beneficial effects on hemodynamics, surgical field quality, recovery characteristics, and nociceptive properties compared with placebo. Although there was no clear-cut superiority of other adjunct pharmacological modalities on hemodynamic responses during surgery, regional blocks were associated with beneficial impacts on both primary and secondary outcomes. In summary, short-acting anesthetics, analgesics and dexmedetomidine seem to improve intraoperative hemodynamics, blood loss, and recovery qualities during TNTS pituitary surgery. However, definitive conclusions cannot be drawn because of methodological heterogeneity in the identified studies.

Neurologic Assessment of the Neurocritical Care Patient

Sedation is a ubiquitous practice in ICUs and NCCUs. It has the benefit of reducing cerebral energy demands, but also precludes an accurate neurologic assessment. Because of this, sedation is intermittently stopped for the purposes of a neurologic assessment, which is termed a neurologic wake-up test (NWT). NWTs are considered to be the gold-standard in continued assessment of brain-injured patients under sedation. NWTs also produce an acute stress response that is accompanied by elevations in blood pressure, respiratory rate, heart rate, and ICP. Utilization of cerebral microdialysis and brain tissue oxygen monitoring in small cohorts of brain-injured patients suggests that this is not mirrored by alterations in cerebral metabolism, and seldom affects oxygenation. The hard contraindications for the NWT are preexisting intracranial hypertension, barbiturate treatment, status epilepticus, and hyperthermia. However, hemodynamic instability, sedative use for primary ICP control, and sedative use for severe agitation or respiratory distress are considered significant safety concerns. Despite ubiquitous recommendation, it is not clear if additional clinically relevant information is gleaned through its use, especially with the contemporaneous utilization of multimodality monitoring. Various monitoring modalities provide unique and pertinent information about neurologic function, however, their role in improving patient outcomes and guiding treatment plans has not been fully elucidated. There is a paucity of information pertaining to the optimal frequency of NWTs, and if it differs based on type of injury. Only one concrete recommendation was found in the literature, exemplifying the uncertainty surrounding its utility. The most common sedative used and recommended is propofol because of its rapid onset, short duration, and reduction of cerebral energy requirements. Dexmedetomidine may be employed to facilitate serial NWTs, and should always be used in the non-intubated patient or if propofol infusion syndrome (PRIS) develops. Midazolam is not recommended due to tissue accumulation and residual sedation confounding a reliable NWT. Thus, NWTs are well-tolerated in selected patients and remain recommended as the gold-standard for continued neuromonitoring. Predicated upon one expert panel, they should be performed at least one time per day. Propofol or dexmedetomidine are the main sedative choices, both enabling a rapid awakening and consistent NWT.

Consensus Statement on Analgo-sedation in Neurocritical Care and Review of Literature

Aim and objective

Our main objective in developing this consensus is to bring together a set of most agreed-upon statements from a panel of global experts that would act as a guide for clinicians working in neurocritical care units (NCCUs).

Background

Given the physiological benefits of analgo-sedation in the NCCU, there is little information on their tailoring in the NCCU. This lack of evidence and guidelines on the use of sedation and analgesia in patients with neurological injury leads to a variation in clinical care based on patient requirements and institutional protocols.

Review results

Thirty-nine international experts agreed to be a member of this consensus panel. A Delphi method based on a Web-based questionnaire developed with Google Forms on a secure institute server was used to seek opinions of experts. Questions were related to sedation and analgesia in the neurocritical care unit. A predefined threshold of agreement was established as 70% to support any recommendation, strong, moderate, or weak. No recommendations were made below this threshold. Responses were collected from all the experts, summated, and expressed as percentage (%). After three rounds, consensus could be reached for 6 statements related to analgesia and 5 statements related to sedation. Consensus could not be reached for 10 statements related to analgesia and 5 statements related to sedation.

Conclusion

This global consensus statement may help in guiding practitioners in clinical decision-making regarding analgo-sedation in the NCCUs, thereby helping in improving patient recovery profiles.

Clinical significance

In the lack of high-level evidence, the recommendations may be seen as the current best clinical practice.

How to cite this article

Prabhakar H, Tripathy S, Gupta N, Singhal V, Mahajan C, Kapoor I, et al. Consensus Statement on Analgo-sedation in Neurocritical Care and Review of Literature. Indian J Crit Care Med 2021;25(2):126–133.

DEXmedetomidine compared to PROpofol in NEurocritical Care [DEXPRONE]: A multicenter retrospective evaluation of clinical utility and safety

PURPOSE

Although guidelines recommend dexmedetomidine (DEX) or propofol (PRO) as preferred sedatives in critically ill adults, comparisons in neurocritical care (NCC) are limited. We aimed to evaluate the clinical utility and safety of DEX compared with PRO in NCC setting.

MATERIALS AND METHODS

This retrospective, multicenter, observational cohort study conducted at three tertiary academic hospitals with Level 1 Trauma Center and Comprehensive Stroke Center designations, compared the clinical indication and safety of DEX vs PRO in patients in NCC setting.

RESULTS

179 patients were included (94 DEX and 85 PRO), median age of 58, 49% were male (DEX) and 58% were male (PRO). PRO was more commonly used to manage agitation. DEX was more commonly used for facilitating extubation, alcohol withdrawal, and sedation during frequent neurologic assessments. Mean Glasgow Coma Scale scores were higher in DEX group (11 vs. 9; p = .04). The duration of either infusions, mechanical ventilation, and lengths of stay were similar. No difference was observed in hypotension or bradycardia rates. Death was significantly higher with PRO (DEX 10% vs. PRO 22%; p = .02).

CONCLUSIONS

DEX and PRO were used for distinct indications in our cohort. Adverse effect profiles and clinical outcome, in the cohorts are largely similar.

Sedatives in neurocritical care: an update on pharmacological agents and modes of sedation

PURPOSE OF REVIEW

In this article, the specific and general indications for sedatives in the neurocritical care unit are discussed, together with an overview on current insights in sedative protocols for these patients. In addition, physiological effects of sedative agents on the central nervous system are reviewed.

RECENT FINDINGS

In the general ICU population, a large body of evidence supports light protocolized sedation over indiscriminate deep sedation. Unfortunately, in patients with severe acute brain injury, the evidence from randomized controlled trials is scarce to nonexistent, and practice is supported by expert opinion, physiological studies and observational or small interventional trials. The different sedatives each have different beneficial effects and side-effects.

SUMMARY

Extrapolating the findings from studies in the general ICU population suggests to reserve deep continuous sedation in the neuro-ICU for specific indications. Although an improved understanding of cerebral physiological changes in patients with brain injury may be helpful to guide individualized sedation, we still lack the evidence base to make broad recommendations for specific patient groups.

The pearls of pediatric sedation: polish the old and embrace the new

Over the past decade, as the complexity and breadth of pediatric procedures increases, the actual choices of approved sedatives have remained relatively stagnant. Since the introduction of midazolam, there has not been a sedative approved for pediatric labelling until December 2018. This December, the European approval of ADV6209 (Ozalin) for pediatric usage marked the newest addition to the pediatric sedative armamentarium in over a decade. This review is timely and significant because it will provide a balanced evaluation of the most common sedatives in use today, the most recent sedative to be approved and, most importantly, a critical look at the literature supporting the latest approaches to the most commonly performed procedures.

The influence of norepinephrine and phenylephrine on cerebral perfusion and oxygenation during propofol-remifentanil and propofol-remifentanil-dexmedetomidine anaesthesia in piglets

Background

Vasopressors are frequently used to increase blood pressure in order to ensure sufficient cerebral perfusion and oxygenation (CPO) during hypotensive periods in anaesthetized patients. Efficacy depends both on the vasopressor and anaesthetic protocol used. Propofol–remifentanil total intravenous anaesthesia (TIVA) is common in human anaesthesia, and dexmedetomidine is increasingly used as adjuvant to facilitate better haemodynamic stability and analgesia. Little is known of its interaction with vasopressors and subsequent effects on CPO. This study investigates the CPO response to infusions of norepinephrine and phenylephrine in piglets during propofol–remifentanil and propofol–remifentanil–dexmedetomidine anaesthesia. Sixteen healthy female piglets (25–34 kg) were randomly allocated into a two-arm parallel group design with either normal blood pressure (NBP) or induced low blood pressure (LBP). Anaesthesia was induced with propofol without premedication and maintained with propofol–remifentanil TIVA, and finally supplemented with continuous infusion of dexmedetomidine. Norepinephrine and phenylephrine were infused in consecutive intervention periods before and after addition of dexmedetomidine. Cerebral perfusion measured by laser speckle contrast imaging was related to cerebral oxygenation as measured by an intracerebral Licox probe (partial pressure of oxygen) and transcranial near infrared spectroscopy technology (NIRS) (cerebral oxygen saturation).

Results

During propofol–remifentanil anaesthesia, increases in blood pressure by norepinephrine and phenylephrine did not change cerebral perfusion significantly, but cerebral partial pressure of oxygen (Licox) increased following vasopressors in both groups and increases following norepinephrine were significant (NBP: P = 0.04, LBP: P = 0.02). In contrast, cerebral oxygen saturation (NIRS) fell significantly in NBP following phenylephrine (P = 0.003), and following both norepinephrine (P = 0.02) and phenylephrine (P = 0.002) in LBP. Blood pressure increase by both norepinephrine and phenylephrine during propofol–remifentanil–dexmedetomidine anaesthesia was not followed by significant changes in cerebral perfusion. Licox measures increased significantly following both vasopressors in both groups, whereas the decreases in NIRS measures were only significant in the NBP group.

Conclusions

Cerebral partial pressure of oxygen measured by Licox increased significantly in concert with the vasopressor induced increases in blood pressure in healthy piglets with both normal and low blood pressure. Cerebral oxygenation assessed by intracerebral Licox and transcranial NIRS showed opposing results to vasopressor infusions.

Electronic supplementary material

The online version of this article (10.1186/s13028-018-0362-z) contains supplementary material, which is available to authorized users.

Neuroleptic malignant syndrome and serotonin syndrome

The clinical manifestation of drug-induced abnormalities in thermoregulation occurs across a variety of drug mechanisms. The aim of this chapter is to review two of the most common drug-induced hyperthermic states, serotonin syndrome and neuroleptic malignant syndrome. Clinical features, pathophysiology, and treatment strategies will be discussed, in addition to differentiating between these two syndromes and differentiating them from other hyperthermic or febrile syndromes. Our goal is to both review the current literature and to provide a practical guide to identification and treatment of these potentially life-threatening illnesses. The diagnostic and treatment recommendations made by us, and by other authors, are likely to change with a better understanding of the pathophysiology of these syndromes.

Use of Dexmedetomidine in Cardiothoracic and Vascular Anesthesia

Dexmedetomidine is a highly selective α₂-adrenergic agonist with analgesic and sedative properties. In the United States, the Food and Drug Administration approved the use of the drug for short-lasting sedation (24 h) in intensive care units (ICUs) in patients undergoing mechanical ventilation and endotracheal intubation. In October 2008, the Food and Drug Administration extended use of the drug for the sedation of nonintubated patients before and during surgical and nonsurgical procedures. In the European Union, the European Medicine Agency approved the use of dexmedetomidine in September 2011 with a single recognized indication: ICU adult patients requiring mild sedation and awakening in response to verbal stimulus. At present, the use of dexmedetomidine for sedation outside the ICU remains an off-label indication. The benefits of dexmedetomidine in critically ill patients and in cardiac, electrophysiology-related, vascular, and thoracic procedures are discussed.

Head Trauma

Head trauma is a common cause of significant morbidity and mortality in dogs and cats. Traumatic brain injury may occur after head trauma. Understanding the pathophysiology of primary and secondary injury after head trauma is essential for management. This article reviews the pathophysiology of head trauma, patient assessment and diagnostics, and treatment recommendations.

The effect of dexmedetomidine on cerebral perfusion and oxygenation in healthy piglets with normal and lowered blood pressure anaesthetized with propofol-remifentanil total intravenous anaesthesia

BACKGROUND

During anaesthesia and surgery, in particular neurosurgery, preservation of cerebral perfusion and oxygenation (CPO) is essential for normal postoperative brain function. The isolated effects on CPO of either individual anaesthetic drugs or entire anaesthetic protocols are of importance in both clinical and research settings. Total intravenous anaesthesia (TIVA) with propofol and remifentanil is widely used in human neuroanaesthesia. In addition, dexmedetomidine is receiving increasing attention as an anaesthetic adjuvant in neurosurgical, intensive care, and paediatric patients. Despite the extensive use of pigs as animal models in neuroscience and the increasing use of both propofol-remifentanil and dexmedetomidine, very little is known about their combined effect on CPO in pigs with uninjured brains. This study investigates the effect of dexmedetomidine on CPO in piglets with normal and lowered blood pressure during background anaesthesia with propofol-remifentanil TIVA. Sixteen healthy female Danish pigs (crossbreeds of Danish Landrace, Yorkshire and Duroc, 25-34 kg) were used. Three animals were subsequently excluded. The animals were randomly allocated into one of two groups with either normal blood pressure (NBP, n = 6) or with induced low blood pressure (LBP, n = 7). Both groups were subjected to the same experimental protocol. Intravenous propofol induction was performed without premedication. Anaesthesia was maintained with propofol-remifentanil TIVA, and later supplemented with continuous infusion of dexmedetomidine. Assessments of cerebral perfusion obtained by laser speckle contrast imaging (LSCI) were related to cerebral oxygenation measures (PbrO2) obtained by an intracerebral Clark-type Licox probe.

RESULTS

Addition of dexmedetomidine resulted in a 32% reduction in median PbrO2 values for the LBP group (P = 0.03), but no significant changes in PbrO2 were observed for the NBP group. No significant changes in LSCI readings were observed in either group between any time points, despite a 28% decrease in the LBP group following dexmedetomidine administration. Caval block resulted in a significant (P = 0.02) reduction in median MAP from 68 mmHg (range 63-85) at PCB to 58 mmHg (range 53-63) in the LBP group, but no significant differences in either PbrO2 or LSCI were observed due to this intervention (P = 0.6 and P = 0.3 respectively).

CONCLUSIONS

Addition of dexmedetomidine to propofol-remifentanil TIVA resulted in a significant decrease in cerebral oxygenation (PbrO2) measurements in piglets with lowered blood pressure. Cerebral perfusion (LSCI) did not decrease significantly in this group. In piglets with normal blood pressure, no significant changes in cerebral perfusion or oxygenation were seen in response to addition of dexmedetomidine to the background anaesthesia.