Review articles: the effects of perioperative and intensive care unit sedation on brain organ dysfunction

Volatile versus propofol sedation after cardiac valve surgery: a single-center prospective randomized controlled trial

BACKGROUND

Optimal intensive care of patients undergoing valve surgery is a complex balancing act between sedation for monitoring and timely postoperative awakening. It remains unclear, if these requirements can be fulfilled by volatile sedations in intensive care medicine in an efficient manner. Therefore, this study aimed to assess the time to extubation and secondary the workload required.

METHODS

We conducted a prospective randomized single-center trial at a tertiary university hospital to evaluate the postoperative management of open valve surgery patients. The study was randomized with regard to the use of volatile sedation compared to propofol sedation. Sedation was discontinued 60 min after admission for critical postoperative monitoring.

RESULTS

We observed a significantly earlier extubation (91 ± 39 min vs. 167 ± 77 min; p < 0.001), eye-opening (86 ± 28 min vs. 151 ± 71 min; p < 0.001) and command compliance (93 ± 38 min vs. 164 ± 75 min; p < 0.001) using volatile sedation, which in turn was associated with a significantly increased workload of a median of 9:56 min (± 4:16 min) set-up time. We did not observe any differences in complications. Cardiopulmonary bypass time did not differ between the groups 101 (IQR 81; 113) versus 112 (IQR 79; 136) minutes p = 0.36.

CONCLUSIONS

Using volatile sedation is associated with few minutes additional workload in assembling and enables a significantly accelerated evaluation of vulnerable patient groups. Volatile sedation has considerable advantages and emerges as a safe sedation technique in our vulnerable study population.

TRIAL REGISTRATION

Clinical trials registration (NCT04958668) was completed on 1 July 2021.

Impact of CPAP on Forehead Near-infrared Spectroscopy Measurements in Patients With Acute Respiratory Failure: Truth or Illusion

BACKGROUND

Critically ill patients with acute respiratory failure admitted to an intensive care unit are at high risk for cerebral hypoxia. We investigated the impact of continuous positive airway pressure (CPAP) therapy on regional cerebral tissue oxygenation (rSO2).

MATERIALS AND METHODS

In total, 40 extubated surgical intensive care unit patients requiring classic oxygen therapy (COT) for acute respiratory failure were examined. Near-infrared spectroscopy (INVOS 5100C, Covidien) was used for 30 minutes to detect bilateral rSO2 during COT via facemask (6 L/min) and CPAP therapy (40% fraction of inspired oxygen, 8 cm H2O CPAP) using a randomized crossover study design. Patients served as their own control. Continuous hemodynamic routine monitoring and blood gas analysis were performed. The effect of CPAP therapy on rSO2 and influence of assessed covariables were investigated using a mixed linear model.

RESULTS

Median rSO2 increased from 57.9% (95% confidence interval [CI], 54.2-61.5) during COT to 62.8% (95% CI, 59.2-66.5) during CPAP therapy (P<0.0001). The estimated difference from the mixed model between COT and CPAP is -5.0 (95% CI, -6.3 to -3.7). Median arterial partial pressure of carbon dioxide decreased from 47.8±5.1 mm Hg during COT to 43.1±5 mm Hg during CPAP (P<0.001), whereas arterial partial pressure of oxygen remained unchanged (P=0.329). In total, 23% of patients had SO2 levels <50%, with a higher prevalence under COT.

CONCLUSIONS

Our results reveal that CPAP therapy compared with COT may influence rSO2 in patients with acute respiratory failure. However, the cause of the rSO2 increase following CPAP application remains to be elucidated, and the accuracy of cerebral oximetry during CPAP therapy in patients with acute respiratory failure remains questionable.

The Impact of Postoperative Intensive Care Unit Admission on Postoperative Hospital Length of Stay and Costs: A Prespecified Propensity-Matched Cohort Study

BACKGROUND

In this prespecified cohort study, we investigated the influence of postoperative admission to the intensive care unit versus surgical ward on health care utilization among patients undergoing intermediate-risk surgery.

METHODS

Of adult surgical patients who underwent general anesthesia without an absolute indication for postoperative intensive care unit admission, 3530 patients admitted postoperatively to an intensive care unit were matched to 3530 patients admitted postoperatively to a surgical ward using a propensity score based on 23 important preoperative and intraoperative predictor variables. Postoperative hospital length of stay and hospital costs were defined as primary and secondary end points, respectively.

RESULTS

Among patients with low propensity for postoperative intensive care unit admission, initial triage to an intensive care unit was associated with increased postoperative length of stay (incidence rate ratio, 1.69 [95% CI, 1.59-1.79]; P < .001) and hospital costs (incidence rate ratio, 1.92 [95% CI, 1.81-2.03]; P < .001). By contrast, postoperative intensive care unit admission of patients with high propensity was associated with decreased postoperative length of stay (incidence rate ratio, 0.90 [95% CI, 0.85-0.95]; P < .001) and costs (incidence rate ratio, 0.92 [95% CI, 0.88-0.97]; P = .001). Decisions regarding postoperative intensive care unit resource utilization were influenced by individual preferences of anesthesiologists and surgeons.

CONCLUSIONS

In patients with an unclear indication for postoperative critical care, intensive care unit admission may negatively impact postoperative hospital length of stay and costs. Postoperative discharge disposition varies substantially based on anesthesia and surgical provider preferences but should optimally be driven by an objective assessment of a patient's status at the end of surgery.

The Benefit of Benzodiazepine Reduction: Improving Sedation in Surgical Intensive Care

Aims:

Sedation, as it is often required in critical care, is associated with immobilization, prolonged ventilation, and increased morbidity. Most sedation protocols are based on benzodiazepines. The presented study analyzes the benefit of benzodiazepine-free sedation.

Methods:

In 2008, 134 patients were treated according to a protocol using benzodiazepine and propofol (Group 1). In 2009, we introduced a new sedation strategy based on sufentanil, nonsteroidal anti-inflammatory drugs, neuroleptics, and antidepressants, which was applied in 140 consecutive patients (Group 2). Depth of sedation, duration of mechanical ventilation, duration of Intensive Care Unit, and hospital stay were analyzed.

Results:

Group 1 had both a longer duration of deep sedation (18.7 ± 2.5 days vs. 12.6 ± 1.85 days, P = 0.031) and a longer duration of controlled ventilation (311, 35 ± 32.69 vs. 143, 96 ± 20.76 h, P < 0.0001) than Group 2. Ventilator days were more frequent in Group 1 (653, 66 ± 98.37 h vs. 478, 89 ± 68.92 h, P = 0.128).

Conclusions:

The benzodiazepine-free sedation protocol has been shown to significantly reduce depth of sedation and controlled ventilation. Additional evidence is needed to ascertain reduction of ventilator days which would not only be of benefit for the patient but also for the hospital Management.

Prolonged Treatment with Propofol Transiently Impairs Proliferation but Not Survival of Rat Neural Progenitor Cells In Vitro

Neurocognitive dysfunction is common in survivors of intensive care. Prolonged sedation has been implicated but the mechanisms are unclear. Neurogenesis continues into adulthood and is implicated in learning. The neural progenitor cells (NPC) that drive neurogenesis have receptors for the major classes of sedatives used clinically, suggesting that interruption of neurogenesis may partly contribute to cognitive decline in ICU survivors. Using an in vitro system, we tested the hypothesis that prolonged exposure to propofol concentration- and duration-dependently kills or markedly decreases the proliferation of NPCs. NPCs isolated from embryonic day 14 Sprague-Dawley rat pups were exposed to 0, 2.5, or 5.0 μg/mL of propofol, concentrations consistent with deep clinical anesthesia, for either 4 or 24 hours. Cells were assayed for cell death and proliferation either immediately following propofol exposure or 24 hours later. NPC death and apoptosis were measured by propidium iodine staining and cleaved caspase-3 immunocytochemistry, respectively, while proliferation was measured by EdU incorporation. Staurosporine (1μM for 6h) was used as a positive control for cell death. Cells were analyzed with unbiased high-throughput immunocytochemistry. There was no cell death at either concentration of propofol or duration of exposure. Neither concentration of propofol impaired NPC proliferation when exposure lasted 4 h, but when exposure lasted 24 h, propofol had an anti-proliferative effect at both concentrations (P < 0.0001, propofol vs. control). However, this effect was transient; proliferation returned to baseline 24 h after discontinuation of propofol (P = 0.37, propofol vs. control). The transient but reversible suppression of NPC proliferation, absence of cytotoxicity, and negligible effect on the neural stem cell pool pool suggest that propofol, even in concentrations used for clinical anesthesia, has limited impact on neural progenitor cell biology.

A randomized controlled trial of daily sedation interruption in critically ill children

Purpose

To compare daily sedation interruption plus protocolized sedation (DSI + PS) to protocolized sedation only (PS) in critically ill children.

Methods

In this multicenter randomized controlled trial in three pediatric intensive care units in the Netherlands, mechanically ventilated critically ill children with need for sedative drugs were included. They were randomly assigned to either DSI + PS or PS only. Children in both study arms received sedation adjusted on the basis of validated sedation scores. Provided a safety screen was passed, children in the DSI + PS group received daily blinded infusions of saline; children in the PS group received blinded infusions of the previous sedatives/analgesics. If a patient’s sedation score indicated distress, the blinded infusions were discontinued, a bolus dose of midazolam was given and the ‘open’ infusions were resumed: DSI + PS at half of infusion rate, PS at previous infusion rate. The primary endpoint was the number of ventilator-free days at day 28. Data were analyzed by intention to treat.

Results

From October 2009 to August 2014, 129 children were randomly assigned to DSI + PS (n = 66) or PS (n = 63). The study was terminated prematurely due to slow recruitment rates. Median number of ventilator-free days did not differ: DSI + PS 24.0 days (IQR 21.6–25.8) versus PS 24.0 days (IQR 20.6–26.0); median difference 0.02 days (95 % CI −0.91 to 1.09), p = 0.90. Median ICU and hospital length of stay were similar in both groups: DSI + PS 6.9 days (IQR 5.2–11.0) versus PS 7.4 days (IQR 5.3–12.8), p = 0.47, and DSI + PS 13.3 days (IQR 8.6–26.7) versus PS 15.7 days (IQR 9.3–33.2), p = 0.19, respectively. Mortality at 30 days was higher in the DSI + PS group than in the PS group (6/66 versus 0/63, p = 0.03), though no causal relationship to the intervention could be established. Median cumulative midazolam dose did not differ: DSI + PS 14.1 mg/kg (IQR 7.6–22.6) versus PS 17.0 mg/kg (IQR 8.2–39.8), p = 0.11.

Conclusion

In critically ill children, daily sedation interruption in addition to protocolized sedation did not improve clinical outcome and was associated with increased mortality compared with protocolized sedation only.

Impact of Sedation on Cognitive Function in Mechanically Ventilated Patients

The practice of sedation dosing strategy in mechanically ventilated patient has a profound effect on cognitive function. We conducted a comprehensive review of outcome of sedation on mental health function in critically ill patients on mechanical ventilation in the intensive care unit (ICU). We specifically evaluated current sedative dosing strategy and the development of delirium, post-traumatic stress disorders (PTSDs) and agitation. Based on this review, heavy dosing sedation strategy with benzodiazepines contributes to cognitive dysfunction. However, outcome for mental health dysfunction is mixed in regard to newer sedatives agents such as dexmedetomidine and propofol. Moreover, studies that examine the impact of sedatives for persistence of PTSD/delirium and its long-term cognitive and functional outcomes for post-ICU patients are frequently underpowered. Most studies suffer from low sample sizes and methodological variations. Therefore, larger randomized controlled trials are needed to properly assess the impact of sedation dosing strategy on cognitive function.

Recent advances in mechanical ventilation in patients without acute respiratory distress syndrome

While being an essential part of general anesthesia for surgery and at times even a life-saving intervention in critically ill patients, mechanical ventilation has a strong potential to cause harm. Certain ventilation strategies could prevent, at least to some extent, the injury caused by this intervention. One essential element of so-called ‘lung-protective’ ventilation is the use of lower tidal volumes. It is uncertain whether higher levels of positive end-expiratory pressures have lung-protective properties as well. There are indications that too high oxygen fractions of inspired air, or too high blood oxygen targets, are harmful. Circumstantial evidence further suggests that spontaneous modes of ventilation are to be preferred over controlled ventilation to prevent harm to respiratory muscle. Finally, the use of restrictive sedation strategies in critically ill patients indirectly prevents ventilation-induced injury, as daily spontaneous awakening and breathing trials and bolus instead of continuous sedation are associated with shorter duration of ventilation and shorten the exposure to the injurious effects of ventilation.

The attributable mortality of delirium in critically ill patients: prospective cohort study

OBJECTIVE

To determine the attributable mortality caused by delirium in critically ill patients.

DESIGN

Prospective cohort study.

SETTING

32 mixed bed intensive care unit in the Netherlands, January 2011 to July 2013.

PARTICIPANTS

1112 consecutive adults admitted to an intensive care unit for a minimum of 24 hours.

EXPOSURES

Trained observers evaluated delirium daily using a validated protocol. Logistic regression and competing risks survival analyses were used to adjust for baseline variables and a marginal structural model analysis to adjust for confounding by evolution of disease severity before the onset of delirium.

MAIN OUTCOME MEASURE

Mortality during admission to an intensive care unit.

RESULTS

Among 1112 evaluated patients, 558 (50.2%) developed at least one episode of delirium, with a median duration of 3 days (interquartile range 2-7 days). Crude mortality was 94/558 (17%) in patients with delirium compared with 40/554 (7%) in patients without delirium (P<0.001). Delirium was significantly associated with mortality in the multivariable logistic regression analysis (odds ratio 1.77, 95% confidence interval 1.15 to 2.72) and survival analysis (subdistribution hazard ratio 2.08, 95% confidence interval 1.40 to 3.09). However, the association disappeared after adjustment for time varying confounders in the marginal structural model (subdistribution hazard ratio 1.19, 95% confidence interval 0.75 to 1.89). Using this approach, only 7.2% (95% confidence interval -7.5% to 19.5%) of deaths in the intensive care unit were attributable to delirium, with an absolute mortality excess in patients with delirium of 0.9% (95% confidence interval -0.9% to 2.3%) by day 30. In post hoc analyses, however, delirium that persisted for two days or more remained associated with a 2.0% (95% confidence interval 1.2% to 2.8%) absolute mortality increase. Furthermore, competing risk analysis showed that delirium of any duration was associated with a significantly reduced rate of discharge from the intensive care unit (cause specific hazard ratio 0.65, 95% confidence interval 0.55 to 0.76).

CONCLUSIONS

Overall, delirium prolongs admission in the intensive care unit but does not cause death in critically ill patients. Future studies should focus on episodes of persistent delirium and its long term sequelae rather than on acute mortality.Trial registration Clinicaltrials.gov NCT01905033.

Randomized ICU trials do not demonstrate an association between interventions that reduce delirium duration and short-term mortality: a systematic review and meta-analysis

OBJECTIVES

We reviewed randomized trials of adult ICU patients of interventions hypothesized to reduce delirium burden to determine whether interventions that are more effective at reducing delirium duration are associated with a reduction in short-term mortality.

DATA SOURCES

We searched CINHAHL, EMBASE, MEDLINE, and the Cochrane databases from 2001 to 2012.

STUDY SELECTION

Citations were screened for randomized trials that enrolled critically ill adults, evaluated delirium at least daily, compared a drug or nondrug intervention hypothesized to reduce delirium burden with standard care (or control), and reported delirium duration and/or short-term mortality (≤ 45 d).

DATA EXTRACTION

In duplicate, we abstracted trial characteristics and results and evaluated quality using the Cochrane risk of bias tool. We performed random effects model meta-analyses and meta-regressions.

DATA SYNTHESIS

We included 17 trials enrolling 2,849 patients which evaluated a pharmacologic intervention (n = 13) (dexmedetomidine [n = 6], an antipsychotic [n = 4], rivastigmine [n = 2], and clonidine [n = 1]), a multimodal intervention (n = 2) (spontaneous awakening [n = 2]), or a nonpharmacologic intervention (n = 2) (early mobilization [n = 1] and increased perfusion [n = 1]). Overall, average delirium duration was lower in the intervention groups (difference = -0.64 d; 95% CI, -1.15 to -0.13; p = 0.01) being reduced by more than or equal to 3 days in three studies, 0.1 to less than 3 days in six studies, 0 day in seven studies, and less than 0 day in one study. Across interventions, for 13 studies where short-term mortality was reported, short-term mortality was not reduced (risk ratio = 0.90; 95% CI, 0.76-1.06; p = 0.19). Across 13 studies that reported mortality, meta-regression revealed that delirium duration was not associated with reduced short-term mortality (p = 0.11).

CONCLUSIONS

A review of current evidence fails to support that ICU interventions that reduce delirium duration reduce short-term mortality. Larger controlled studies are needed to establish this relationship.

Intravenous Patient-controlled Analgesia Has a Positive Effect on the Prognosis of Delirium in Patients Undergoing Orthopedic Surgery

BACKGROUND

Postoperative delirium is relatively common. However, the relationship between intravenous patient-controlled analgesia (IV-PCA) and delirium has not been thoroughly investigated. The aim of this study was to evaluate the effects of IV-PCA on the prognosis of postoperative delirium in patients undergoing orthopedic surgery.

METHODS

Medical records of 129 patients with postoperative delirium were reviewed. Patients were divided into two groups according to whether they used IV-PCA with fentanyl and ketorolac. The IV-PCA group consisted of 73 patients who were managed with IV-PCA; the NO-PCA group consisted of 56 patients who were managed without PCA.

RESULTS

Incidences of multiple psychiatric consultations and prolonged delirium were significantly lower in patients using IV-PCA with fentanyl and ketorolac than in those without PCA.

CONCLUSIONS

We recommend the use of IV-PCA for pain control and management of delirium in patients with postoperative delirium.

Optimal sedation in pediatric intensive care patients: a systematic review

PURPOSE

Sedatives administered to critically ill children should be titrated to effect, because both under- and oversedation may have negative effects. We conducted a systematic review to examine reported incidences of under-, optimal, and oversedation in critically ill children receiving intensive care.

METHODS

A systematic literature search using predefined criteria was performed in PubMed and Embase to identify all articles evaluating level of sedation in PICU patients receiving continuous sedation. Two authors independently recorded: study objective, study design, sample size, age range, details of study intervention (if applicable), sedatives used, length of sedation, sedation scale used, and incidences of optimal, under-, and oversedation as defined in the studies.

RESULTS

Twenty-five studies were included. Two studies evaluated sedation level as primary study outcome; the other 23 as secondary outcomes. Together, these studies investigated 1,163 children; age range, 0-18 years. Across studies, children received many different sedative agents and sedation level was assessed with 12 different sedation scales. Optimal sedation was ascertained in 57.6 % of the observations, under sedation in 10.6 %, and oversedation in 31.8 %.

CONCLUSIONS

This study suggests that sedation in the PICU is often suboptimal and seldom systematically evaluated. Oversedation is more common than undersedation. As oversedation may lead to longer hospitalization, tolerance, and withdrawal, preventing oversedation in pediatric intensive care deserves greater attention.

Delirium

Delirium was described by Hippocrates over 2500 years ago and it remains an important clinical problem today. Work continues to improve definition, prevention, diagnosis, and treatment, but relatively young science remains. Delirium affects 12 500 000 patients and costs $152 000 000 000 every year. Up to 80% of mechanically ventilated patients experience delirium, which exists as a spectrum of acute brain organ dysfunction. Multiple theories exist, including contribution from baseline pathology, medications, surgical inflammation, and environment. Biochemical models point to pathophysiology. Delirium remains largely preventable through planning and subgroup identification. Validated objective assessment models aid diagnosis, whereas protocolized multimodal intervention remains best practice. Pharmacotherapy, as chemical restraint, is reserved for cases of potential harm to self or others. Observation obviates mechanical restraint. The contribution of delirium to cognitive decline remains controversial and concerning. As dollars shrink and cost does not, delirium becomes increasingly important. In an aging population of increasing frailty, delirium will contribute increasingly to long-term morbidity and even mortality.

A pilot study of cerebral and haemodynamic physiological changes during sedation with dexmedetomidine or propofol in patients with acute brain injury

Sedation for the mechanically-ventilated, brain-injured patient remains challenging. The purpose of this pilot study was to compare the cerebral physiologic effects of sedation with propofol versus dexmedetomidine in mechanically-ventilated, brain-injured patients. Using a randomised, crossover, unblinded clinical trial, we enrolled patients with severe brain injury (Glasgow Coma Score ≤8) from traumatic injury, subarachnoid haemorrhage or intracerebral haemorrhage undergoing multimodal monitoring (intracranial pressure, brain temperature, oximetry and microdialysis). Patients received an infusion of either propofol or dexmedetomidine for six hours and then a crossover for the subsequent six hours after sufficient washout/in. Clinical and physiological measurements were recorded hourly. In eight patients, (four traumatic injury, three subarachnoid haemorrhage and one intracerebral haemorrhage), the mean dose of propofol used was 25.5 µg/kg/minute while the mean dose of dexmedetomidine was 0.54 µg/kg/hour. All subjects were effectively sedated to a goal of Richmond Agitation Sedation Scale -2 and Bispectral Index of 50-70 throughout the study period. We did not observe any statistically significant differences between the groups in systemic or cerebral physiologic metrics. Though differences were noted in cerebral metabolic substrates (lactate/pyruvate ratio), none were statistically significant. In our pilot cohort, dexmedetomidine and propofol appear equally effective in sedating severely brain-injured patients and neither is associated with adverse physiological effects as measured by multimodal monitoring. Larger long-term studies are required to determine whether clinically favourable benefits demonstrated in the medical critical care setting also apply to this patient population.

Anesthetic neurotoxicity

Concerns for toxic effects of anesthesia to the brains of the young and the elderly are mounting. While experimental evidence for such effects in the developing brain is strong, the underlying mechanisms are less well understood and debate continues as to whether young humans are at risk for anesthetic neurotoxicity. The phenomenon of postoperative cognitive deterioration in the elderly remains controversial. Time course, severity, and whether or not it persists long term are under debate. For both patient groups, today's evidence is not sufficient to guide change in clinical practice. Well-designed research is therefore imperative to tackle this critical issue.

The lung and the brain: a dangerous cross-talk

Brain or lung injury or both are frequent causes of admission to intensive care units and are associated with high morbidity and mortality rates. Mechanical ventilation, which is commonly used in the management of these critically ill patients, can induce an inflammatory response, which may be involved in distal organ failure. Thus, there may be a complex crosstalk between the lungs and other organs, including the brain. Interestingly, survivors from acute lung injury/acute respiratory distress syndrome frequently have some cognitive deterioration at hospital discharge. Such neurologic dysfunction might be a secondary marker of injury and the neuroanatomical substrate for downstream impairment of other organs. Brainlung interactions have received little attention in the literature, but recent evidence suggests that both the lungs and brain can promote inflammation through common mediators. The present commentary discusses the main physiological issues related to brain-lung interactions.