Propofol dosing regimens for ICU sedation based upon an integrated pharmacokinetic-pharmacodynamic model

Pharmacokinetics and exposure-safety relationship of ciprofol for sedation in mechanically ventilated patients in the intensive care unit

Ciprofol (HSK3486) is a newly developed, highly selective γ-aminobutyric acid-A (GABAA) receptor potentiator that is recently approved for a new indication of sedation for patients in the intensive care unit (ICU) in China. This analysis aimed to characterize the population pharmacokinetics (PopPKs) of ciprofol and evaluate the relationship of exposure with hypotension in mechanically ventilated patients in the ICU. A total of 462 subjects with 3918 concentration measurements from two clinical trials of mechanically ventilated patients in the ICU, four clinical trials of elective surgical patients, and six clinical trials of healthy subjects were used in the PopPK analysis. Exposure-safety relationship for hypotension was evaluated based on the data gathered from 112 subjects in two clinical trials of mechanically ventilated patients in the ICU. Ciprofol pharmacokinetics (PKs) was adequately described by a three-compartment linear disposition model with first-order elimination. Body weight, age, sex, blood sampling site (vein vs. arterial), study design (long-term infusion vs. short-term infusion), and patient population (ICU vs. non-ICU) were identified as statistically significant covariates on the PKs of ciprofol. Within the exposure range of the mechanically ventilated ICU patient population, no meaningful association was observed between ciprofol exposure and the incidence of hypotension. These results support the dosing regimen currently used in mechanically ventilated patients in the ICU.

Ketamine in Critically Ill Patients: Use, Perceptions, and Potential Barriers

Objective: To evaluate practitioner use of ketamine and identify potential barriers to use in acutely and critically ill patients. To compare characteristics, beliefs, and practices of ketamine frequent users and non-users. Methods: An online survey developed by members of the Society of Critical Care Medicine (SCCM) Clinical Pharmacy and Pharmacology Section was distributed to physician, pharmacist, nurse practitioner, physician assistant and nurse members of SCCM. The online survey queried SCCM members on self-reported practices regarding ketamine use and potential barriers in acute and critically ill patients. Results: Respondents, 341 analyzed, were mostly adult physicians, practicing in the United States at academic medical centers. Clinicians were comfortable or very comfortable using ketamine to facilitate intubation (80.0%), for analgesia (77.9%), procedural sedation (79.4%), continuous ICU sedation (65.8%), dressing changes (62.4%), or for asthma exacerbation and status epilepticus (58.8% and 40.4%). Clinicians were least comfortable with ketamine use for alcohol withdrawal and opioid detoxification (24.7% and 23.2%). Most respondents reported "never" or "infrequently" using ketamine preferentially for continuous IV analgesia (55.6%) or sedation (61%). Responses were mixed across dosing ranges and duration. The most common barriers to ketamine use were adverse effects (42.6%), other practitioners not routinely using the medication (41.5%), lack of evidence (33.5%), lack of familiarity (33.1%), and hospital/institutional policy guiding the indication for use (32.3%). Conclusion: Although most critical care practitioners report feeling comfortable using ketamine, there are many inconsistencies in practice regarding dose, duration, and reasons to avoid or limit ketamine use. Further educational tools may be targeted at practitioners to improve appropriate ketamine use.

Impact of Pharmacist Monitoring of Serum Triglycerides for Critically Ill Patients Receiving Propofol

Background: Elevated serum triglycerides due to the use of propofol for sedation in the ICU is associated with adverse effects and serum triglyceride monitoring may be improved by pharmacists. Objective: To determine if there was improvement in serum triglyceride monitoring in ICU patients receiving propofol for sedation after implementation of a pharmacist-driven triglyceride monitoring protocol. Methods: This was a single-center pre-post-intervention retrospective cohort study. The protocol was implemented on January 10 2019. Data were collected over 1 year, and patients were divided between those started on propofol before and after protocol implementation. Results: There were 412 patients included in the final analysis with no significant differences between groups. There was a significant increase in the number of patients who had a triglyceride concentration obtained after protocol implementation (31.1% pre-vs 64.0% post-protocol; P < .001). For patients on propofol greater than 24 h, there was a significant increase in baseline triglyceride concentration obtained (7.6% pre-vs 15.1% post-protocol; P = .043). More instances of elevated triglyceride concentrations were identified by pharmacists than other providers (9 vs 5; P < .001). Time between propofol being ordered and first triglyceride concentration ordered was shorter (.86 days pre-protocol vs .71 days post-protocol; P = .064), but not statistically significant. Conclusion: Implementation of a pharmacist-driven protocol in the ICU increased the number of serum triglyceride levels obtained for patients receiving propofol for sedation. Pharmacists can improve triglyceride monitoring in patients receiving propofol and future studies should investigate the impact on outcomes.

Opioid sensitivity in treated and untreated obstructive sleep apnoea: a prospective cohort study

BACKGROUND

Opioid administration to patients with obstructive sleep apnoea (OSA) is controversial because they are believed to be more sensitive to opioids. However, objective data on opioid effects in OSA are lacking. We tested the hypothesis that subjects with untreated OSA have increased sensitivity to opioids compared with subjects without OSA, or with OSA treated with continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BIPAP).

METHODS

This was a single-centre, prospective cohort study in subjects without OSA (n=20), with untreated OSA (n=33), or with treated OSA (n=21). OSA diagnosis was verified using type III (in-home) polysomnography. Subjects received a stepped-dose remifentanil infusion (target effect-site concentrations of 0.5, 1, 2, 3, 4 ng ml-1). Primary outcome was miosis (pupil area fractional change), the most sensitive opioid effect. Secondary outcomes were ventilatory rate, end-expired CO2, sedation, and thermal analgesia.

RESULTS

There were no differences in miosis between untreated OSA subjects (mean=0.51, 95% confidence interval [CI] 0.41-0.61) and subjects without OSA (mean=0.49, 95% CI 0.36-0.62) (mean difference=0.02, 95% CI -0.18 to 0.22); between treated OSA subjects (mean=0.56, 95% CI 0.43-0.68) and subjects without OSA (difference=0.07, 95% CI -0.16 to 0.29); or between untreated OSA and treated OSA (difference=-0.05, 95% CI -0.25 to 0.16). There were no significant differences between subjects without OSA, untreated OSA, and treated OSA in ventilatory rate, end-expired CO2, sedation, or thermal analgesia responses to remifentanil. There was no relationship between OSA severity and magnitude of opioid effects.

CONCLUSIONS

Neither obstructive sleep apnoea nor obstructive sleep apnoea treatment affected sensitivity to the miotic, sedative, analgesic, or respiratory depressant effects of the opioid remifentanil in awake adults. These results challenge conventional notions of opioid effects in obstructive sleep apnoea.

CLINICAL TRIAL REGISTRATION

NCT02898792 (clinicaltrials.gov).

ICU- and ventilator-free days with isoflurane or propofol as a primary sedative - A post- hoc analysis of a randomized controlled trial

PURPOSE

To compare ICU-free (ICU-FD) and ventilator-free days (VFD) in the 30 days after randomization in patients that received isoflurane or propofol without receiving the other sedative.

MATERIALS AND METHODS

A recent randomized controlled trial (RCT) compared inhaled isoflurane via the Sedaconda® anaesthetic conserving device (ACD) with intravenous propofol for up to 54 h (Meiser et al. 2021). After end of study treatment, continued sedation was locally determined. Patients were eligible for this post-hoc analysis only if they had available 30-day follow-up data and never converted to the other drug in the 30 days from randomization. Data on ventilator use, ICU stay, concomitant sedative use, renal replacement therapy (RRT) and mortality were collected.

RESULTS

Sixty-nine of 150 patients randomized to isoflurane and 109 of 151 patients randomized to propofol were eligible. After adjusting for potential confounders, the isoflurane group had more ICU-FD than the propofol group (17.3 vs 13.8 days, p = 0.028). VFD for the isoflurane and propofol groups were 19.8 and 18.5 respectively (p = 0.454). Other sedatives were used more frequently (p < 0.0001) and RRT started in a greater proportion of patients in the propofol group (p = 0.011).

CONCLUSIONS

Isoflurane via the ACD was not associated with more VFD but with more ICU-FD and less concomitant sedative use.

Clinical validation of an adapted Eleveld Model for high-dose propofol treatments for depression

Repeated administration of high doses of propofol to patients with treatment-resistant depression (TRD) has been shown to produce antidepressant effects in small clinical trials. These effects can be elicited when the patient's EEG burst-suppression ratio (BSR) is maintained at 70-90% for 15 min in repeated treatments. This deep anesthesia domain lies beyond the range of current propofol pharmacokinetic/pharmacodynamic (PK/PD) models. In this study, we adapt the Eleveld model for use at deep anesthesia levels with a BSR endpoint, with the goal of aiding the estimation of the dosage of propofol needed to achieve 70-90% BSR for 15 min. We test the ability of the adapted model to predict BSR for these treatments. Twenty participants underwent 6-9 treatments of high doses of propofol (5-9 of which were included in this analysis) for a total of 115 treatments. To adapt the Eleveld model for this endpoint, we optimized the model parameters Ke0, γ and Ce50. These parameters were then used in the adapted model to estimate second-by-second BSR for each treatment. Estimated BSR was compared with observed BSR for each treatment of each participant. Median absolute performance error (MdAPE) between the estimated and observed BSR (25th-75th percentile) was 6.63 (3.79-12.96) % points and 8.51 (4.32-16.74) % between the estimated and observed treatment duration. This predictive performance is statistically significantly better at predicting BSR compared with the standard Eleveld model at deep anesthesia levels. Our adapted Eleveld model provides a useful tool to aid dosing propofol for high-dose anesthetic treatments for depression.

Propofol Sedation Washouts in Critically Ill Infants: A Case Series

Medically complex infants are experiencing longer hospital stays, more invasive procedures, and increasingly involved therapeutic interventions that often require long-term analgesia and sedation. This is most commonly achieved with continuous intravenous infusions of opioids and benzodiazepines. There are times when patients develop a tolerance for these medications or the clinical scenario necessitates a rapid wean of them. A rapid wean of either class of medication can lead to increased signs of pain and agitation or withdrawal symptoms. As a result, when a rapid wean is needed or there has been a failure to control symptoms with conventional measures, alternative therapies are considered. Propofol, a sedative hypnotic typically used for general anesthesia and procedural sedation, is one such medication. It has effectively been used for short-term sedation in adults and children to facilitate weaning benzodiazepines and opioids. There is a paucity of data on the use of propofol in infants for this purpose. Here we describe the use of propofol to rapidly wean high-dose sedation and analgesia medications, a propofol sedation washout, in 3 infants. The washouts proved to be safe and efficacious. Based on institutional experience and a literature review, considerations and recommendations are made for propofol sedation washouts in infants.

Efficacy and safety of ciprofol versus propofol for the induction of anesthesia in adult patients: a multicenter phase 2a clinical trial

BACKGROUND

Ciprofol is a novel 2, 6-disubstituted phenolic derivative anesthetic that binds to the gamma-aminobutyric acid-A receptor.

AIM

To determine the equally potent dose of ciprofol compared with propofol as an induction agent for general anesthesia in patients undergoing selective surgery, and to assess its safety.

METHOD

A total of 109 patients undergoing selective non-emergency, non-cardiothoracic or non-neurosurgical surgery requiring tracheal intubation for general anesthesia were enrolled. Ten patients per group were assigned to ciprofol-0.3, 0.4 and 0.5 mg/kg, and propofol-2.0 or 2.5 mg/kg groups, respectively to receive an intravenous bolus dose. An additional 20 patients were enrolled in the ciprofol-0.3, 0.5 or propofol-2.0 mg/kg groups. The primary outcome was the success rate of induction defined as a Modified Observer's Assessment of Alertness/Sedation (MOAA/S) ≤ 1 after the initial bolus dose. The secondary outcomes included the time to reach MOAA/S ≤ 1, the time to loss of the eyelash reflex, the incidences and severity of adverse events (AEs).

RESULTS

The success rates were 100% for all 5 groups. The mean time to MOAA/S ≤ 1 and the time to loss of the eyelash reflex were not different among the 5 groups, regardless of whether a top-up dose was needed. There were no significant differences in the incidences and severity of AEs in the dose ranges investigated of ciprofol vs. propofol.

CONCLUSION

The efficacy and safety of a single bolus dose of ciprofol-0.5 mg/kg for the general anesthesia induction in selective surgery patients was comparable to that of propofol-2.0 mg/kg.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03698617, retrospectively registered.

Electroencephalography spectral edge frequency and suppression rate-guided sedation in patients with COVID-19: A randomized controlled trial

Background

Sedation in coronavirus disease 2019 (COVID-19) patients has been identified as a major challenge. We aimed to investigate whether the use of a multiparameter electroencephalogram (EEG) protocol to guide sedation in COVID-19 patients would increase the 30-day mechanical ventilation-free days (VFD).

Methods

We conducted a double-blind randomized clinical trial. We included patients with severe pneumonia due to COVID-19 who required mechanical ventilation (MV) and deep sedation. We randomized to the control (n = 25) or multiparameter group (n = 25). Sedation in the intervention group was administered following the standard institutional protocols together with a flow chart designed to reduce the propofol administration dose if the EEG suppression rate was over 2% or the spectral edge frequency 95 (SEF95) was below 10 Hz. We performed an intention-to-treat analysis to evaluate our primary outcome (30-day VFD).

Results

There was no difference in VFD at day 30 (median: 11 [IQR 0–20] days in the control group vs. 0 [IQR 0–21] days in the BIS multiparameter group, p = 0.87). Among secondary outcomes, we documented a 17% reduction in the total adjusted propofol administered during the first 5 days of the protocol [median: 2.3 (IQR 1.9–2.8) mg/k/h in the control group vs. 1.9(IQR 1.5–2.2) mg/k/h in the MP group, p = 0.005]. This was accompanied by a higher average BIS value in the intervention group throughout the treatment period.

Conclusion

A sedation protocol guided by multivariate EEG-derived parameters did not increase the 30-day VFD. However, the intervention led to a reduction in total propofol administration.

Remimazolam besylate versus propofol for long-term sedation during invasive mechanical ventilation: a pilot study

Objective

The aim of this study was to evaluate the efficacy and safety of remimazolam besylate compared with propofol in maintaining mild-to-moderate sedation in patients receiving long-term mechanical ventilation.

Methods

In this single-centered randomized pilot study, adult patients mechanically ventilated longer than 24 h were randomized to receive remimazolam besylate or propofol. The target sedation range was − 3 to 0 on the Richmond Agitation and Sedation Scale (RASS). The primary outcome was the percentage of time in the target sedation range without rescue sedation. The secondary outcomes were ventilator-free days at day 7, the length of ICU stay and 28-day mortality.

Results

Thirty patients were assigned to each group. No difference was identified between the remimazolam group and propofol group in median age [60.0 (IQR, 51.5–66.3) years vs. 64.0 (IQR, 55.0–69.3) years, respectively, p = 0.437] or the median duration of study drug infusion [55.0 (IQR, 28.3–102.0) hours vs. 41.0 (IQR, 24.8–74.3) hours, respectively, p = 0.255]. The median percentage of time in the target RASS range without rescue sedation was similar in remimazolam and propofol groups [73.2% (IQR, 41.5–97.3%) vs. 82.8% (IQR, 65.6–100%), p = 0.269]. No differences were identified between the two groups in terms of ventilator-free days at day 7, length of ICU stay, 28-day mortality or adverse events.

Conclusions

This pilot study suggested that remimazolam besylate was effective and safe for long-term sedation in mechanically ventilated patients compared with propofol.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04168-w.

Sedation Effects Produced by a Ciprofol Initial Infusion or Bolus Dose Followed by Continuous Maintenance Infusion in Healthy Subjects: A Phase 1 Trial

Introduction

The effects of continuous infusions of ciprofol on its pharmacodynamic and pharmacokinetic properties and safety profiles in healthy Chinese subjects were evaluated.

Methods

In this open-label, randomized, two-way cross-over study, subjects received initial doses of continuous ciprofol/propofol as an infusion for 30 min in part 1 (n = 8) and a bolus dose in part 2 (n = 8) followed by maintenance infusions for a total of 4 h in part 1 and 12 h in part 2. Each subject participated in both parts with a washout time of at least 40 h.

Results

The safety and tolerability parameters of ciprofol were similar to those of propofol, and all treatment-emergent adverse events were mild. The incidences of injection pain and respiratory depression in subjects given ciprofol were lower than those receiving propofol. The pharmacokinetic parameters C_max, t_max, t_1/2, λz and MRT for ciprofol and propofol were similar, while CL, V_d and V_ss were statistically significantly different. Pharmacodynamic parameters including the Richmond Agitation Sedation Scale and bispectral index profiles of ciprofol were similar to those of propofol.

Conclusion

Ciprofol has potential for clinical application for continuous intravenous infusion to maintain sedation for 12 h with the same safety, tolerability and efficacy as propofol.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01914-4.

Protein Binding and Population Pharmacokinetics of Dexmedetomidine after Prolonged Infusions in Adult Critically Ill Patients

PURPOSE

Dexmedetomidine (DEX) is a highly selective α₂-adrenoceptor agonist with high protein binding of 94%. Critical illness may affect protein binding and the pharmacokinetic (PK) parameters of many drugs, including DEX. In critically ill patients receiving prolonged infusions of DEX, there is little information documenting the relationship between key pathophysiologic factors and DEX protein binding or PK parameters. The purpose of this study was to characterize the protein binding and PK profile of prolonged DEX infusion in critically ill patients.

METHODS

Critically ill, adult intensive care unit patients at a university hospital in Hong Kong were studied. The association between the pathophysiologic changes of critical illness and protein binding was evaluated using a generalized estimating equation. A population pharmacokinetic model to establish the PK profile of DEX was developed, and key pathophysiologic covariate effects of severity of illness, organ dysfunction measures, and altered protein binding on DEX PK parameters in this critically ill population were evaluated.

FINDINGS

A total of 22 critically ill patients and 1 healthy control were included. Mean protein binding of DEX in the critically ill patients was 90.4% (95% CI, 89.1-91.7), which was 4% lower than that in the healthy control. The PK data were adequately described by a 2-compartment model. The estimated population mean (relative standard error [RSE]) values of systemic clearance (CL), volume of distribution of the central compartment (V2), intercompartmental clearance (Q), and V_d in the peripheral compartment (V3) were 38.6 (11.7) L/h, 32.1 (46.1) L, 114.5 (58.3) L/h and 95.1 (30.6) L, respectively. The corresponding estimated interindividual variability expressed as CV% (RSE) was 52.4 (23.8) for CL, 172.9 (19.3) for V2, 123.7 (33.7) for Q, and 106 (39.9) for V3. No significant explanatory pathophysiologic covariates were identified.

IMPLICATIONS

Although a marginally significant reduction of protein binding in critically ill patients was demonstrated, the magnitude of the difference was unlikely to be of clinical significance. Higher alanine aminotransferase concentration was associated with decreased protein binding. No significant pathophysiologic covariates were associated with the observed PK parameters. The high interindividual variability of PK parameters supports the current practice of dose titration to ensure the desired clinical effects of DEX infusion in the intensive care unit setting.

Current State of Analgesia and Sedation in the Pediatric Intensive Care Unit

Critically ill pediatric patients often require complex medical procedures as well as invasive testing and monitoring which tend to be painful and anxiety-provoking, necessitating the provision of analgesia and sedation to reduce stress response. Achieving the optimal combination of adequate analgesia and appropriate sedation can be quite challenging in a patient population with a wide spectrum of ages, sizes, and developmental stages. The added complexities of critical illness in the pediatric population such as evolving pathophysiology, impaired organ function, as well as altered pharmacodynamics and pharmacokinetics must be considered. Undersedation leaves patients at risk of physical and psychological stress which may have significant long term consequences. Oversedation, on the other hand, leaves the patient at risk of needing prolonged respiratory, specifically mechanical ventilator, support, prolonged ICU stay and hospital admission, and higher risk of untoward effects of analgosedative agents. Both undersedation and oversedation put critically ill pediatric patients at high risk of developing PICU-acquired complications (PACs) like delirium, withdrawal syndrome, neuromuscular atrophy and weakness, post-traumatic stress disorder, and poor rehabilitation. Optimal analgesia and sedation is dependent on continuous patient assessment with appropriately validated tools that help guide the titration of analgosedative agents to effect. Bundled interventions that emphasize minimizing benzodiazepines, screening for delirium frequently, avoiding physical and chemical restraints thereby allowing for greater mobility, and promoting adequate and proper sleep will disrupt the PICU culture of immobility and reduce the incidence of PACs.

Adjusted vs Total Body Weight-Based Dosing of Sedation and Analgesia Used in the Intensive Care Unit

Background: The purpose of this study was to evaluate if dosing fentanyl, dexmedetomidine, and propofol based on ideal or adjusted vs actual weight in patients would decrease overall opioid and sedative use. Methods: This was a retrospective chart review comparing adjusted vs actual weight-based dosing protocol of mechanically ventilated (MV) intensive care unit (ICU) adult patients who required fentanyl and either propofol or dexmedetomidine. Results: A total of 261 patients were included in which 101 patients were in the actual weight group and 160 patients were in the adjusted weight group. Total doses per MV day of fentanyl was 1042 ± 1060 µg in the actual weight group vs 901 ± 1025 µg in the adjusted weight group (P = .13). Total doses per MV day of midazolam was 20 ± 19 mg in the actual group vs 15 ± 19 mg adjusted group (P = .02). Average MV days was 8.2 vs 7.1 days, ICU length of stay was 10.6 vs 9.4 days, and self-extubation rates were 17.8% vs 4.4% in the actual group and adjusted group, respectively. Conclusion: Total midazolam doses per MV day were lower in the adjusted group. No significant change was seen in MV days, ICU length of stay, or self-extubation rates.

Terminal Withdrawal of Mechanical Ventilation: A Hospice Perspective for the Intensivist

The intensive care unit (ICU) and hospice inpatient unit (IPU) environments differ in many ways. Although both endeavor to provide the best care possible for their patients, the day-to-day goals of these environments are almost antithetical. Similarly, the experiences and expertise of the staff differ. When performing a similar clinical task, it may be addressed in different ways because each group is engrained in their primary day-to-day focus. Terminal withdrawal of mechanical ventilation is a procedure that is performed in both ICUs and some hospice IPUs. Previous examinations of this subject have been based largely upon the correlative background, practices, and perceptions of the ICU prescriber. The purpose of this review is to examine how the manner in which this procedure is performed in the hospice environment may differ in ways that the intensivist can incorporate into their own plan of care, or better appreciate when making the decision to remove mechanical ventilation in the critical care unit or transfer the patient to a hospice environment for the procedure to be completed.

Effects of Propofol on Respiratory Drive and Patient-ventilator Synchrony during Pressure Support Ventilation in Postoperative Patients: A Prospective Study

BACKGROUND

Propofol is increasingly used during partial support mechanical ventilation such as pressure support ventilation (PSV) in postoperative patients. However, breathing pattern, respiratory drive, and patient-ventilator synchrony are affected by the sedative used and the sedation depth. The present study aimed to evaluate the physiologic effects of varying depths of propofol sedation on respiratory drive and patient-ventilator synchrony during PSV in postoperative patients.

METHODS

Eight postoperative patients receiving PSV for <24 h were enrolled. Propofol was administered to achieve and maintain a Ramsay score of 4, and the inspiratory pressure support was titrated to obtain a tidal volume (VT) of 6-8 ml/kg. Then, the propofol dose was reduced to achieve and maintain a Ramsay score of 3 and then 2. At each Ramsay level, the patient underwent 30-min trials of PSV. We measured the electrical activity of the diaphragm, flow, airway pressure, neuro-ventilatory efficiency (NVE), and patient-ventilator synchrony.

RESULTS

Increasing the depth of sedation reduced the peak and mean electrical activity of the diaphragm, which suggested a decrease in respiratory drive, while VT remained unchanged. The NVE increased with an increase in the depth of sedation. Minute ventilation and inspiratory duty cycle decreased with an increase in the depth of sedation, but this only achieved statistical significance between Ramsay 2 and both Ramsay 4 and 3 (P < 0.05). The ineffective triggering index increased with increasing sedation depth (9.5 ± 4.0%, 6.7 ± 2.0%, and 4.2 ± 2.1% for Ramsay 4, 3, and 2, respectively) and achieved statistical significance between each pair of depth of sedation (P < 0.05). The depth of sedation did not affect gas exchange.

CONCLUSIONS

Propofol inhibits respiratory drive and deteriorates patient-ventilator synchrony to the extent that varies with the depth of sedation. Propofol has less effect on breathing pattern and has no effect on VT and gas exchange in postoperative patients with PSV.

Does Propofol Sedation Contribute to Overall Energy Provision in Mechanically Ventilated Critically Ill Adults? A Retrospective Observational Study

BACKGROUND

Propofol sedation is common in critically ill patients, providing energy of 1.1 kcal/mL when administered as a 1% solution. We aimed to determine the proportion of energy administered as propofol on days 1-5 in the intensive care unit (ICU) and any association with outcomes.

METHODS

Retrospective observational study in a quaternary ICU from January-December 2012. Inclusion criteria were length of stay (LOS) ≥5 days, age ≥18 years, and provision of mechanical ventilation (MV) for ≥5 days. Outcome measures included proportion of total daily energy provided as propofol, overall energy balance, hospital mortality, duration of MV, and ICU LOS.

RESULTS

Data from 370 patients were analyzed, 87.8% (n = 325) of whom received propofol during days 1-5 in ICU. A median [interquartile range (IQR)] of 119 [50-730] kcal was provided as propofol per patient-day. Proportion of energy provided by propofol as a percentage of total energy delivered was 55.4%, 15.4%, 9.3%, 7.9%, and 9.9% days 1-5, respectively. Patients administered propofol received a greater proportion of their total daily energy prescription compared with those who were not (P < .01). Proportion of energy provided as propofol was not significantly different based on hospital mortality (P = .62), duration of MV (P = .50), or ICU LOS (P = .15).

CONCLUSION

Propofol contributes to overall energy intake on days 1-5 of ICU admission. Energy balance was higher in those receiving propofol. No association was found between the proportion of energy delivered as propofol and outcomes.

Persistence of Delirium after Cessation of Sedatives and Analgesics and Impact on Clinical Outcomes in Critically Ill Patients

STUDY OBJECTIVE

As delirium is a common manifestation in critically ill patients and is associated with worse clinical outcomes, we sought to characterize the reversibility of delirium after discontinuation of sedation and to determine whether sedation-associated delirium that rapidly reverses impacts clinical outcomes.

DESIGN

Post hoc subgroup analysis of prospectively collected data from a previously published study.

PATIENTS

Seventy adults admitted to a medical intensive care unit (ICU) between March and July 2012 who required mechanical ventilation with continuous analgesia and/or sedation and underwent a spontaneous awakening trial (SAT).

MEASUREMENTS AND MAIN RESULTS

Patients were grouped into four categories: delirium free, rapidly reversible delirium (RRD; defined as delirium always resolving within 4 hrs of stopping sedatives), persistent delirium (PD; defined as delirium always persisting for ≥ 4 hours after stopping sedatives), or mixed delirium (consisting of RRD and PD episodes). The incidence of the four delirium subtypes and their associations with clinical outcomes were evaluated. A validated, guideline-recommended, bedside delirium monitoring instrument-the Confusion Assessment Method for the ICU (CAM-ICU)-was used to assess for the presence or absence of delirium. Clinical outcomes included ventilator-free days at day 28, ICU and hospital length of stay, 28-day mortality, and patient disposition; time to first CAM-ICU becoming negative (delirium free) for a continuous 48-hour duration was also assessed. A total of 103 SATs were performed in the 70 patients. Of the 103 SATs, 28 (27.2%) were CAM-ICU negative before the SAT. Of the remaining 75 SATs, PD was present for the majority of SATs (62 [82.7%]); RRD was present after 13 (17.3%) SATs. On a patient level, 17 patients (24.3%) were always delirium free before cessation of medications for continuous sedation. Of the 53 patients with delirium before undergoing an SAT, 11 (20.8%) had RRD, 2 (3.8%) had mixed delirium, and 40 (75.5%) had PD. Proportional odds logistic regression adjusting for age, Acute Physiology and Chronic Health Evaluation II score, sepsis, and preexisting hypertension showed that patients with PD had a higher probability of longer ICU length of stay (odds ratio 4.01 [95% confidence interval 1.36-11.77], p=0.011), but those with RRD did not.

CONCLUSION

Despite the cessation of medications for continuous sedation, delirium persisted for the majority of patients and was associated with worse outcomes, which attests to the importance of strategies to minimize sedation.

Review of Continuous Infusion Neuromuscular Blocking Agents in the Adult Intensive Care Unit

The use of continuous infusion neuromuscular blocking agents remains controversial. The clinical benefit of these medications may be overshadowed by concerns of propagating intensive care unit-acquired weakness, which may prolong mechanical ventilation and impair the inability to assess neurologic function or pain. Despite these risks, the use of neuromuscular blocking agents in the intensive care unit is indicated in numerous clinical situations. Understanding pharmacologic nuances and clinical roles of these agents will aid in facilitating safe use in a variety of acute disease processes. This article provides clinicians with information regarding pharmacologic differences, indication for use, adverse effects, recommended doses, ancillary care, and monitoring among agents used for continuous neuromuscular blockade.

Alpha-2 agonists for sedation of mechanically ventilated adults in intensive care units: a systematic review

BACKGROUND

Care of critically ill patients in intensive care units (ICUs) often requires potentially invasive or uncomfortable procedures, such as mechanical ventilation (MV). Sedation can alleviate pain and discomfort, provide protection from stressful or harmful events, prevent anxiety and promote sleep. Various sedative agents are available for use in ICUs. In the UK, the most commonly used sedatives are propofol (Diprivan(®), AstraZeneca), benzodiazepines [e.g. midazolam (Hypnovel(®), Roche) and lorazepam (Ativan(®), Pfizer)] and alpha-2 adrenergic receptor agonists [e.g. dexmedetomidine (Dexdor(®), Orion Corporation) and clonidine (Catapres(®), Boehringer Ingelheim)]. Sedative agents vary in onset/duration of effects and in their side effects. The pattern of sedation of alpha-2 agonists is quite different from that of other sedatives in that patients can be aroused readily and their cognitive performance on psychometric tests is usually preserved. Moreover, respiratory depression is less frequent after alpha-2 agonists than after other sedative agents.

OBJECTIVES

To conduct a systematic review to evaluate the comparative effects of alpha-2 agonists (dexmedetomidine and clonidine) and propofol or benzodiazepines (midazolam and lorazepam) in mechanically ventilated adults admitted to ICUs.

DATA SOURCES

We searched major electronic databases (e.g. MEDLINE without revisions, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE and Cochrane Central Register of Controlled Trials) from 1999 to 2014.

METHODS

Evidence was considered from randomised controlled trials (RCTs) comparing dexmedetomidine with clonidine or dexmedetomidine or clonidine with propofol or benzodiazepines such as midazolam, lorazepam and diazepam (Diazemuls(®), Actavis UK Limited). Primary outcomes included mortality, duration of MV, length of ICU stay and adverse events. One reviewer extracted data and assessed the risk of bias of included trials. A second reviewer cross-checked all the data extracted. Random-effects meta-analyses were used for data synthesis.

RESULTS

Eighteen RCTs (2489 adult patients) were included. One trial at unclear risk of bias compared dexmedetomidine with clonidine and found that target sedation was achieved in a higher number of patients treated with dexmedetomidine with lesser need for additional sedation. The remaining 17 trials compared dexmedetomidine with propofol or benzodiazepines (midazolam or lorazepam). Trials varied considerably with regard to clinical population, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded outcome assessors. Compared with propofol or benzodiazepines (midazolam or lorazepam), dexmedetomidine had no significant effects on mortality [risk ratio (RR) 1.03, 95% confidence interval (CI) 0.85 to 1.24, I (2) = 0%; p = 0.78]. Length of ICU stay (mean difference -1.26 days, 95% CI -1.96 to -0.55 days, I (2) = 31%; p = 0.0004) and time to extubation (mean difference -1.85 days, 95% CI -2.61 to -1.09 days, I (2) = 0%; p < 0.00001) were significantly shorter among patients who received dexmedetomidine. No difference in time to target sedation range was observed between sedative interventions (I (2) = 0%; p = 0.14). Dexmedetomidine was associated with a higher risk of bradycardia (RR 1.88, 95% CI 1.28 to 2.77, I (2) = 46%; p = 0.001).

LIMITATIONS

Trials varied considerably with regard to participants, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded assessors.

CONCLUSIONS

Evidence on the use of clonidine in ICUs is very limited. Dexmedetomidine may be effective in reducing ICU length of stay and time to extubation in critically ill ICU patients. Risk of bradycardia but not of overall mortality is higher among patients treated with dexmedetomidine. Well-designed RCTs are needed to assess the use of clonidine in ICUs and identify subgroups of patients that are more likely to benefit from the use of dexmedetomidine.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014014101.

FUNDING

The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit is core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates.

Prolonged infusion of sedatives and analgesics in adult intensive care patients: A systematic review of pharmacokinetic data reporting and quality of evidence

Although pharmacokinetic (PK) data for prolonged sedative and analgesic agents in intensive care unit (ICU) has been described, the number of publications in this important area appear relatively few, and PK data presented is not comprehensive. Known pathophysiological changes in critically ill patients result in altered drug PK when compared with non-critically ill patients. ClinPK Statement was recently developed to promote consistent reporting in PK studies, however, its applicability to ICU specific PK studies is unclear. In this systematic review, we assessed the overall ClinPK Statement compliance rate, determined the factors affecting compliance rate, graded the level of PK evidence and assessed the applicability of the ClinPK Statement to future ICU PK studies. Of the 33 included studies (n=2016), 22 (67%) were low evidence quality descriptive studies (Level 4). Included studies had a median compliance rate of 80% (IQR 66% to 86%) against the ClinPK Statement. Overall pooled compliance rate (78%, 95% CI 73% to 83%) was stable across time (P=0.38), with higher compliance rates found in studies fitting three compartments models (88%, P<0.01), two compartments models (83%, P<0.01) and one compartment models (77%, P=0.17) than studies fitting noncompartmental or unspecified models (69%) (P<0.01). Data unique to the interpretation of PK data in critically ill patients, such as illness severity (48%), organ dysfunction (36%) and renal replacement therapy use (32%), were infrequently reported. Discrepancy between the general compliance rate with ClinPK Statement and the under-reporting of ICU specific parameters suggests that the applicability of the ClinPK Statement to ICU PK studies may be limited in its current form.

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.

Effects of dexmedetomidine and propofol on patient-ventilator interaction in difficult-to-wean, mechanically ventilated patients: a prospective, open-label, randomised, multicentre study

Background

Dexmedetomidine can be used for sedation of mechanically ventilated patients and has minor respiratory effects. The aim of this study was to compare the incidence of patient-ventilator dyssynchronies during sedation with dexmedetomidine or propofol.

Methods

We conducted a multicentre, prospective, open-label, randomised clinical trial, comparing dexmedetomidine with standard propofol sedation at three intensive care units of university hospitals in Italy. Twenty difficult-to-wean patients for whom the first weaning trial had failed and who were on pressure support ventilation were randomised to receive sedation with either dexmedetomidine or propofol at a similar level of sedation (Richmond Agitation-Sedation Scale [RASS] score +1 to −2). The asynchrony index (AI) was calculated using tracings of airflow, airway pressure and electrical activity of the diaphragm sampled at 0, 0.5, 1, 2, 6, 12, 18 and 24 h.

Results

The mean AI was lower with dexmedetomidine than with propofol from 2 h onwards, although the two groups significantly differed only at 12 h (2.68 % vs 9.10 %, p < 0.05). No further difference was observed at 18 and 24 h.

Conclusions

When sedation with propofol and dexmedetomidine was compared at similar RASS scores of patients in whom first weaning trial had failed, the AI was lower with dexmedetomidine than with propofol, and this difference was statistically significant at 12 h. These results suggest that sedation with dexmedetomidine may offer some advantages in terms of patient-ventilator synchrony.

Determination of total and unbound propofol in patients during intensive care sedation by ultrafiltration and LC-MS/MS

For the quantification of propofol total and unbound drug concentrations a sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated. To separate unbound propofol an ultrafiltration step before sample preparation was performed. Both the ultrafiltrate and plasma samples were extracted with solid-phase extraction and substituted with deuterated propofol as an internal standard. Separation was performed by gradient elution using UPLC-like system and analyzed by MS/MS consisting of an electrospray ionization source. To detect low and high concentration levels of propofol two calibration curves were identified and showed linearity within the range of 1-50ng/ml and 50-20000ng/ml. The lower limit of quantification was 1ng/ml. Intra- and interassay precision and accuracy did not exceed ±15%. The method was applied to a clinical study during intensive care treatment of patients after coronary artery bypass grafting.

Comparison of dexmedetomidine, propofol and midazolam for short-term sedation in postoperatively mechanically ventilated neurosurgical patients

BACKGROUND

Effective management of analgesia and sedation in the intensive care unit depends on the needs of the patient, subjective and/or objective measurement and drug titration to achieve specific endpoints.

AIM

The present study compared the efficacy of dexmedetomidine, propofol and midazolam for sedation in neurosurgical patients for postoperative mechanical ventilation.

MATERIALS AND METHODS

Ninety patients aged 20-65 years, ASA physical status I to III, undergoing neurosurgery and requiring postoperative ventilation were included. The patients were randomly divided into three groups of 30 each. Group D received dexmedetomidine 1 mcg/kg over 15 minutes as a loading dose, followed by 0.4-0.7 mcg/kg/h. Group P received propofol 1 mg/kg over 15 minutes as a loading dose, followed by 1-3 mg/kg/h. Group M received midazolam 0.04 mg/kg over 15 minutes as a loading dose, followed by 0.08 mg/kg/h.

MEASUREMENTS

Heart rate, mean arterial pressure, sedation level, fentanyl requirement, ventilation and extubation time were recorded.

RESULTS

Adequate sedation level was achieved with all three agents. Dexmedetomidine group required less fentanyl for postoperative analgesia. In group D there was a decrease in HR after dexmedetomidine infusion (p<0.05), but there was no significant difference in HR between group P and group M. After administration of study drug there was a significant decrease in MAP comparison to baseline value in all groups at all time intervals (p<0.05), except postextubation period (p>0.05). Extubation time was lowest in group P (p<0.05).

CONCLUSION

Dexmedetomidine is safer and equally effective agent compared to propofol and midazolam for sedation of neurosurgical mechanically ventilated patients with good hemodynamic stability and extubation time as rapid as propofol. Dexmedetomidine also reduced postoperative fentanyl requirements.

Top 10 myths regarding sedation and delirium in the ICU

The management of pain, agitation, and delirium in critically ill patients can be complicated by multiple factors. Decisions to administer opioids, sedatives, and antipsychotic medications are frequently driven by a desire to facilitate patients' comfort and their tolerance of invasive procedures or other interventions within the ICU. Despite accumulating evidence supporting new strategies to optimize pain, sedation, and delirium practices in the ICU, many critical care practitioners continue to embrace false perceptions regarding appropriate management in these critically ill patients. This article explores these perceptions in more detail and offers new evidence-based strategies to help critical care practitioners better manage sedation and delirium, particularly in ICU patients.

Hypnosis control based on the minimum concentration of anesthetic drug for maintaining appropriate hypnosis

This paper proposes a novel hypnosis control method using Auditory Evoked Potential Index (aepEX) as a hypnosis index. In order to avoid side effects of an anesthetic drug, it is desirable to reduce the amount of an anesthetic drug during surgery. For this purpose many studies of hypnosis control systems have been done. Most of them use Bispectral Index (BIS), another hypnosis index, but it has problems of dependence on anesthetic drugs and nonsmooth change near some particular values. On the other hand, aepEX has an ability of clear distinction between patient consciousness and unconsciousness and independence of anesthetic drugs. The control method proposed in this paper consists of two elements: estimating the minimum effect-site concentration for maintaining appropriate hypnosis and adjusting infusion rate of an anesthetic drug, propofol, using model predictive control. The minimum effect-site concentration is estimated utilizing the property of aepEX pharmacodynamics. The infusion rate of propofol is adjusted so that effect-site concentration of propofol may be kept near and always above the minimum effect-site concentration. Simulation results of hypnosis control using the proposed method show that the minimum concentration can be estimated appropriately and that the proposed control method can maintain hypnosis adequately and reduce the total infusion amount of propofol.

Approaches for dosage individualisation in critically ill patients

INTRODUCTION

Pharmacokinetic variability in critically ill patients is the result of the overlapping of multiple pathophysiological and clinical factors. Unpredictable exposure from standard dosage regimens may influence the outcome of treatment. Therefore, strategies for dosage individualisation are recommended in this setting.

AREAS COVERED

The authors focus on several approaches for dosage individualisation that have been developed, ranging from the well-established therapeutic drug monitoring (TDM) up to the innovative application of pharmacogenomics criteria. Furthermore, the authors summarise the specific population pharmacokinetic models for different drugs developed for critically ill patients to improve the initial dosage selection and the Bayesian forecasting of serum concentrations. The authors also consider the use of Monte Carlo simulation for the selection of dosage strategies.

EXPERT OPINION

Pharmacokinetic/pharmacodynamics (PK/PD) modelling and dosage individualisation methods based on mathematical and statistical criteria will contribute in improving pharmacologic treatment in critically ill patients. Moreover, substantial effort will be necessary to integrate pharmacogenomics criteria into critical care practice. The lack of availability of target biomarkers for dosage adjustment emphasizes the value of TDM which allows a large part of treatment outcome variability to be controlled.

Intensive care sedation: the past, present and the future

Despite the universal prescription of sedative drugs in the intensive care unit (ICU), current practice is not guided by high-level evidence. Landmark sedation trials have made significant contributions to our understanding of the problems associated with ICU sedation and have promoted changes to current practice. We identified challenges and limitations of clinical trials which reduced the generalizability and the universal adoption of key interventions. We present an international perspective regarding current sedation practice and a blueprint for future research, which seeks to avoid known limitations and generate much-needed high-level evidence to better guide clinicians' management and therapeutic choices of sedative agents.

Dexmedetomidine use in the ICU: are we there yet?

Expanded abstract

Clinical practice guidelines for the management of pain, agitation, and delirium in adult patients in the intensive care unit

OBJECTIVE

To revise the "Clinical Practice Guidelines for the Sustained Use of Sedatives and Analgesics in the Critically Ill Adult" published in Critical Care Medicine in 2002.

METHODS

The American College of Critical Care Medicine assembled a 20-person, multidisciplinary, multi-institutional task force with expertise in guideline development, pain, agitation and sedation, delirium management, and associated outcomes in adult critically ill patients. The task force, divided into four subcommittees, collaborated over 6 yr in person, via teleconferences, and via electronic communication. Subcommittees were responsible for developing relevant clinical questions, using the Grading of Recommendations Assessment, Development and Evaluation method (http://www.gradeworkinggroup.org) to review, evaluate, and summarize the literature, and to develop clinical statements (descriptive) and recommendations (actionable). With the help of a professional librarian and Refworks database software, they developed a Web-based electronic database of over 19,000 references extracted from eight clinical search engines, related to pain and analgesia, agitation and sedation, delirium, and related clinical outcomes in adult ICU patients. The group also used psychometric analyses to evaluate and compare pain, agitation/sedation, and delirium assessment tools. All task force members were allowed to review the literature supporting each statement and recommendation and provided feedback to the subcommittees. Group consensus was achieved for all statements and recommendations using the nominal group technique and the modified Delphi method, with anonymous voting by all task force members using E-Survey (http://www.esurvey.com). All voting was completed in December 2010. Relevant studies published after this date and prior to publication of these guidelines were referenced in the text. The quality of evidence for each statement and recommendation was ranked as high (A), moderate (B), or low/very low (C). The strength of recommendations was ranked as strong (1) or weak (2), and either in favor of (+) or against (-) an intervention. A strong recommendation (either for or against) indicated that the intervention's desirable effects either clearly outweighed its undesirable effects (risks, burdens, and costs) or it did not. For all strong recommendations, the phrase "We recommend …" is used throughout. A weak recommendation, either for or against an intervention, indicated that the trade-off between desirable and undesirable effects was less clear. For all weak recommendations, the phrase "We suggest …" is used throughout. In the absence of sufficient evidence, or when group consensus could not be achieved, no recommendation (0) was made. Consensus based on expert opinion was not used as a substitute for a lack of evidence. A consistent method for addressing potential conflict of interest was followed if task force members were coauthors of related research. The development of this guideline was independent of any industry funding.

CONCLUSION

These guidelines provide a roadmap for developing integrated, evidence-based, and patient-centered protocols for preventing and treating pain, agitation, and delirium in critically ill patients.

The antinociceptive and antihyperalgesic effects of topical propofol on dorsal horn neurons in the rat

BACKGROUND

Propofol (2,6-diisopropylphenol) is an IV anesthetic used for general anesthesia. Recent evidence suggests that propofol-anesthetized patients experience less postoperative pain, and that propofol has analgesic properties when applied topically. We presently investigated the antinociceptive effects of topical propofol using behavioral and single-unit electrophysiological methods in rats.

METHODS

In behavioral experiments with rats, we assessed the effect of topical hindpaw application of propofol (1%-25%) on heat and mechanically evoked paw withdrawals. In electrophysiological experiments, we recorded from lumbar dorsal horn wide dynamic range (WDR)-type neurons in pentobarbital-anesthetized rats. We assessed the effect of topical application of propofol to the ipsilateral hindpaw on neuronal responses elicited by noxious heat, cold, and mechanical stimuli. We additionally tested whether propofol blocks heat sensitization of paw withdrawals and WDR neuronal responses induced by topical application of allyl isothiocyanate (AITC; mustard oil).

RESULTS

Topical application of propofol (1%-25%) significantly increased the mean latency of the thermally evoked hindpaw withdrawal reflex on the treated (but not opposite) side in a concentration-dependent manner, with no effect on mechanically evoked hindpaw withdrawal thresholds. Propofol also prevented shortening of paw withdrawal latency induced by AITC. In electrophysiological experiments, topical application of 10% and 25% propofol, but not 1% propofol or vehicle (10% intralipid), to the ipsilateral hindpaw significantly attenuated the magnitude of responses of WDR neurons to noxious heating of glabrous hindpaw skin with no significant change in thermal thresholds. Maximal suppression of noxious heat-evoked responses was achieved 15 minutes after application followed by recovery to the pre-propofol baseline by 30 minutes. Responses to skin cooling or graded mechanical stimuli were not significantly affected by any concentration of propofol. Topical application of AITC enhanced the noxious heat-evoked response of dorsal horn neurons. This enhancement of heat-evoked responses was attenuated when 10% propofol was applied topically after application of AITC.

CONCLUSIONS

The results indicate that topical propofol inhibits responses of WDR neurons to noxious heat consistent with analgesia, and reduced AITC sensitization of WDR neurons consistent with an antihyperalgesic effect. These results are consistent with clinical studies demonstrating reduced postoperative pain in surgical patients anesthetized with propofol. The mechanism of analgesic action of topical propofol is not clear, but may involve desensitization of TRPV1 or TRPA1 receptors expressed in peripheral nociceptive nerve endings, engagement of endocannabinoids, or activation of peripheral γ-aminobutyric acid A receptors.

Diurnal sedative changes during intensive care: impact on liberation from mechanical ventilation and delirium

OBJECTIVE

To determine whether benzodiazepine and propofol doses are increased at night and whether daytime and nighttime sedative doses are associated with delirium, coma, and delayed liberation from mechanical ventilation.

DESIGN

Single-center, prospective cohort study nested within the Awakening and Breathing Controlled randomized trial.

SETTING

Saint Thomas Hospital in Nashville, TN, from 2004 to 2006.

PATIENTS

Adult patients receiving mechanical ventilation for >12 hrs with continuous recording of hourly sedation dosing.

INTERVENTIONS

We measured hourly doses of benzodiazepine and propofol exposure during the daytime (7 AM to 11 PM) and nighttime (11 PM to 7 AM) for 5 days. We quantified nighttime dose increases by subtracting the average hourly daytime dose on the preceding day from subsequent average hourly nighttime dose. We used multivariable logistic regression to determine whether daytime and nighttime dose increases were independently associated with delirium, coma, and delayed liberation from mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Among 140 patients, the median Acute Physiology and Chronic Health Evaluation II score was 27 (interquartile range 22-33). Among those receiving the sedatives, benzodiazepine and propofol doses were increased at night on 40% and 41% of patient-days, respectively. Of 485 patient-days, delirium was present on 160 (33%) and coma on 206 (42%). In adjusted models, greater daytime benzodiazepine dose was independently associated with failed spontaneous breathing trial and extubation, and subsequent delirium (p<.02 for all). Nighttime increase in benzodiazepine dose was associated with failed spontaneous breathing trial (p<.01) and delirium (p=.05). Daytime propofol dose was marginally associated with subsequent delirium (p=.06).

CONCLUSIONS

Nearly half of mechanically ventilated intensive care unit patients received greater doses of sedation at night, a practice associated with failed spontaneous breathing trials, coma, and delirium. Over the first 5 days in our study, patients spent 75% of their time in coma or delirium, outcomes that may be reduced by efforts to decrease sedative exposure during both daytime and nighttime hours in the intensive care unit.