Accumulation of midazolam after repeated dosage in patients receiving mechanical ventilation in an intensive care unit

The Association of Proning and Stroke among Deeply Sedated Critically Ill SARS-CoV-2 (COVID-19) Patients

There has been an increasing incidence of stroke cases among SARS-CoV-2 (COVID-19) patients who were deeply sedated and underwent proning positioning. We reviewed the association of proning and sedations used to the development of stroke, including demographic profiles of patients with COVID-19 infection in the critical care unit. There was a significant association seen among COVID-19 patients in the ICU who underwent proning to the development of stroke, with up to 15 times risk of having stroke (p value = 0.007) than those who were not proned during their course of ICU stay. Patients who were given propofol and fentanyl as sedation during proning for more than 24 hours was significantly associated with the development of stroke (p value = 0.004). Patient risk factors were also studied (age variability, hypertension, diabetes, smoking, and alcoholism) and showed that patients who were alcoholic beverage drinkers were significantly associated to the development of stroke during proning (p value = <0.001). The usual risk factors for stroke in the general population (hypertension, diabetes, and cigarette smoking) were not associated with stroke development during proning, strengthening the fact that proning during COVID-19 infection is an independent risk factor for the development of stroke thus needing stroke surveillance during the duration of proning.

Treatment of Refractory Convulsive Status Epilepticus: A Comprehensive Review by the American Epilepsy Society Treatments Committee

Purpose:

Established tonic–clonic status epilepticus (SE) does not stop in one-third of patients when treated with an intravenous (IV) benzodiazepine bolus followed by a loading dose of a second antiseizure medication (ASM). These patients have refractory status epilepticus (RSE) and a high risk of morbidity and death. For patients with convulsive refractory status epilepticus (CRSE), we sought to determine the strength of evidence for 8 parenteral ASMs used as third-line treatment in stopping clinical CRSE.

Methods:

A structured literature search (MEDLINE, Embase, CENTRAL, CINAHL) was performed to identify original studies on the treatment of CRSE in children and adults using IV brivaracetam, ketamine, lacosamide, levetiracetam (LEV), midazolam (MDZ), pentobarbital (PTB; and thiopental), propofol (PRO), and valproic acid (VPA). Adrenocorticotropic hormone (ACTH), corticosteroids, intravenous immunoglobulin (IVIg), magnesium sulfate, and pyridoxine were added to determine the effectiveness in treating hard-to-control seizures in special circumstances. Studies were evaluated by predefined criteria and were classified by strength of evidence in stopping clinical CRSE (either as the last ASM added or compared to another ASM) according to the 2017 American Academy of Neurology process.

Results:

No studies exist on the use of ACTH, corticosteroids, or IVIg for the treatment of CRSE. Small series and case reports exist on the use of these agents in the treatment of RSE of suspected immune etiology, severe epileptic encephalopathies, and rare epilepsy syndromes. For adults with CRSE, insufficient evidence exists on the effectiveness of brivaracetam (level U; 4 class IV studies). For children and adults with CRSE, insufficient evidence exists on the effectiveness of ketamine (level U; 25 class IV studies). For children and adults with CRSE, it is possible that lacosamide is effective at stopping RSE (level C; 2 class III, 14 class IV studies). For children with CRSE, insufficient evidence exists that LEV and VPA are equally effective (level U, 1 class III study). For adults with CRSE, insufficient evidence exists to support the effectiveness of LEV (level U; 2 class IV studies). Magnesium sulfate may be effective in the treatment of eclampsia, but there are only case reports of its use for CRSE. For children with CRSE, insufficient evidence exists to support either that MDZ and diazepam infusions are equally effective (level U; 1 class III study) or that MDZ infusion and PTB are equally effective (level U; 1 class III study). For adults with CRSE, insufficient evidence exists to support either that MDZ infusion and PRO are equally effective (level U; 1 class III study) or that low-dose and high-dose MDZ infusions are equally effective (level U; 1 class III study). For children and adults with CRSE, insufficient evidence exists to support that MDZ is effective as the last drug added (level U; 29 class IV studies). For adults with CRSE, insufficient evidence exists to support that PTB and PRO are equally effective (level U; 1 class III study). For adults and children with CRSE, insufficient evidence exists to support that PTB is effective as the last ASM added (level U; 42 class IV studies). For CRSE, insufficient evidence exists to support that PRO is effective as the last ASM used (level U; 26 class IV studies). No pediatric-only studies exist on the use of PRO for CRSE, and many guidelines do not recommend its use in children aged <16 years. Pyridoxine-dependent and pyridoxine-responsive epilepsies should be considered in children presenting between birth and age 3 years with refractory seizures and no imaging lesion or other acquired cause of seizures. For children with CRSE, insufficient evidence exists that VPA and diazepam infusion are equally effective (level U, 1 class III study). No class I to III studies have been reported in adults treated with VPA for CRSE. In comparison, for children and adults with established convulsive SE (ie, not RSE), after an initial benzodiazepine, it is likely that loading doses of LEV 60 mg/kg, VPA 40 mg/kg, and fosphenytoin 20 mg PE/kg are equally effective at stopping SE (level B, 1 class I study).

Conclusions:

Mostly insufficient evidence exists on the efficacy of stopping clinical CRSE using brivaracetam, lacosamide, LEV, valproate, ketamine, MDZ, PTB, and PRO either as the last ASM or compared to others of these drugs. Adrenocorticotropic hormone, IVIg, corticosteroids, magnesium sulfate, and pyridoxine have been used in special situations but have not been studied for CRSE. For the treatment of established convulsive SE (ie, not RSE), LEV, VPA, and fosphenytoin are likely equally effective, but whether this is also true for CRSE is unknown. Triple-masked, randomized controlled trials are needed to compare the effectiveness of parenteral anesthetizing and nonanesthetizing ASMs in the treatment of CRSE.

Care of the intubated emergency department patient

BACKGROUND

Emergency physicians perform tracheal intubation and initiate mechanical ventilation for critically ill patients on a daily basis. With the current national challenges of intensive care unit bed availability, intubated patients now often remain in the emergency department (ED) for exceedingly long periods of time. As a result, care of the intubated patient falls to the emergency physician (EP). Given the potential for significant morbidity and mortality, it is crucial for the EP to possess the most current, up-to-date information pertaining to the care of intubated patients.

DISCUSSION

This article discusses critical aspects in the ED management of intubated and mechanically ventilated patients. Specifically, emphasis is placed on providing adequate sedation and analgesia, limiting the use of neuromuscular blocking agents, correctly setting and adjusting the mechanical ventilator, utilizing appropriate monitoring modalities, and providing key supportive measures. Despite these measures, inevitably, some patients deteriorate while receiving mechanical ventilation. The article concludes with a discussion outlining a step-wise approach to evaluating the intubated patient who develops respiratory distress or circulatory compromise. With this information, the EP can more effectively care for ventilated patients while minimizing morbidity, and ultimately, improving outcome.

CONCLUSION

Essential components of the care of intubated ED patients includes administering adequate sedative and analgesic medications, using lung-protective ventilator settings with attention to minimizing ventilator-induced lung injury, elevating the head of the bed in the absence of contraindications, early placement of an orogastric tube, and providing prophylaxis for stress-related mucosal injury and deep venous thrombosis when indicated.

In-vivo kinetics of the interaction between midazolam and erythromycin in rats, taking account of metabolic intermediate complex formation

To predict, quantitatively, the extent of drug interaction during repeated administration of a metabolic inhibitor, we analysed the effects of erythromycin treatment under several regimens on the area under the concentration curve (AUC) of midazolam in rats. Midazolam was administered into the portal vein 12 h after erythromycin treatment for 1, 2 or 3 days, or 12, 24, 36, 48, 72 and 96 h after erythromycin treatment for 4 days, and the plasma-concentration profiles of midazolam were analysed to assess the AUC. Moreover, the contents of total cytochrome P450 and inactive metabolic intermediate (MI) complex were simultaneously quantitated. While the AUC value of midazolam was not affected by the administration of erythromycin for 1 day, repeated administration of erythromycin evoked an increase in AUC ratio (AUC in erythromycin-treated rats/AUC in vehicle-treated rats), which reached a maximum value of 1.99 at 12 h after 4 days' treatment with erythromycin. The total content of cytochrome P450 in liver microsomes was unaffected by erythromycin treatment. Although the MI complex was undetectable after 1 day's treatment with erythromycin, its content increased with duration of erythromycin treatment, and the complex disappeared after the end of erythromycin treatment with a half-life of 12.3 h. In conclusion, the interaction between erythromycin and midazolam could be well predicted when the formation of MI complex in the liver was taken into account.

Sedation and analgesia for the mechanically ventilated patient

Mechanically ventilated patients in the intensive care unit routinely require sedative and analgesic medications to manage pain and anxiety. These medications may have unpredictable effects with long-term use. Strategies that may help to improve patient outcomes include thoughtful selection of medications, use of objective sedation and pain scales, and implementation of protocolized sedation.

Reversal of sedation with flumazenil in a child after traumatic brain injury

The authors report on a case of successful reversal of sedation with flumazenil, a benzodiazepine antagonist, in a child following a moderate traumatic brain injury and demonstrate the utility of flumazenil to reverse benzodiazepine effects in traumatically injured children.

Comparison of buccal midazolam with rectal diazepam in the treatment of prolonged seizures in Ugandan children: a randomized clinical trial

OBJECTIVE

Our goal was to compare the efficacy and safety of buccal midazolam with rectal diazepam in the treatment of prolonged seizures in Ugandan children.

METHODS

This was a single-blind, randomized clinical trial in which 330 patients were randomly assigned to receive buccal midazolam or rectal diazepam. The trial was conducted in the pediatric emergency unit of the national referral hospital of Uganda. Consecutive patients who were aged 3 months to 12 years and presented while convulsing or who experienced a seizure that lasted >5 minutes were randomly assigned to receive buccal midazolam plus rectal placebo or rectal diazepam plus buccal placebo. The primary outcome of this study was cessation of visible seizure activity within 10 minutes without recurrence in the subsequent hour.

RESULTS

Treatment failures occurred in 71 (43.0%) of 165 patients who received rectal diazepam compared with 50 (30.3%) of 165 patients who received buccal midazolam. Malaria was the most common underlying diagnosis (67.3%), although the risk for failure of treatment for malaria-related seizures was similar: 35.8% for rectal diazepam compared with 31.8% for buccal midazolam. For children without malaria, buccal midazolam was superior (55.9% vs 26.5%). Respiratory depression occurred uncommonly in both of the treatment arms.

CONCLUSION

Buccal midazolam was as safe as and more effective than rectal diazepam for the treatment of seizures in Ugandan children, although benefits were limited to children without malaria.

Effect of a nurse-implemented sedation protocol on the incidence of ventilator-associated pneumonia*

OBJECTIVE

To determine whether the use of a nurse-implemented sedation protocol could reduce the incidence of ventilator-associated pneumonia in critically ill patients.

DESIGN

Two-phase (before-after), prospective, controlled study.

SETTING

University-affiliated, 11-bed medical intensive care unit.

PATIENTS

Patients requiring mechanical ventilation for >or=48 hrs and sedative infusion with midazolam or propofol alone.

INTERVENTIONS

During the control phase, sedatives were adjusted according to the physician's decision. During the protocol phase, sedatives were adjusted according to a protocol developed by a multidisciplinary team including nurses and physicians. The protocol was based on the Cambridge scale, and sedation level was adjusted every 3 hrs by the nurses. Standard practices, including weaning from the ventilator and diagnosis of VAP, were the same during both study phases.

MEASUREMENTS AND MAIN RESULTS

A total of 423 patients were enrolled (control group, n = 226; protocol group, n = 197). The incidence of VAP was significantly lower in the protocol group compared with the control group (6% and 15%, respectively, p = .005). By univariate analysis (log-rank test), only use of a nurse-implemented protocol was significantly associated with a decrease of incidence of VAP (p < .01). A nurse-implemented protocol was found to be independently associated with a lower incidence of VAP after adjustment on Simplified Acute Physiology Score II in the multivariate Cox proportional hazards model (hazard rate, 0.81; 95% confidence interval, 0.62-0.95; p = .03). The median duration of mechanical ventilation was significantly shorter in the protocol group (4.2 days; interquartile range, 2.1-9.5) compared with the control group (8 days; interquartile range, 2.2-22.0; p = .001), representing a 52% relative reduction. Extubation failure was more frequently observed in the control group compared with the protocol group (13% and 6%, respectively, p = .01). There was no significant difference in in-hospital mortality (38% vs. 45% in the protocol vs. control group, respectively, p = .22).

CONCLUSIONS

In patients receiving mechanical ventilation and requiring sedative infusions with midazolam or propofol, the use of a nurse-implemented sedation protocol decreases the rate of VAP and the duration of mechanical ventilation.

Sedation in the mechanically ventilated patient

OBJECTIVE

To discuss the approach to sedation of the mechanically ventilated patient.

DATA SYNTHESIS

Mechanically ventilated patients in the intensive care unit frequently require sedation and analgesia for anxiety and pain experienced during the time they are intubated. Multiple drugs are available for this purpose. Strategies that optimize comfort while minimizing the predilection for sedative and analgesic drug accumulation with prolongation of effect have been shown to improve outcomes. In particular, such strategies may decrease mechanical ventilation duration, intensive care unit length of stay, and complications associated with critical illness.

CONCLUSIONS

Sedation and analgesia are important in the management of patients who require mechanical ventilation. An evidence-based approach to administering sedatives and analgesics is necessary to optimize short- and long-term outcomes in mechanically ventilated patients.

Withdrawal following sufentanil/propofol and sufentanil/midazolam

PURPOSE

Patients in the ICU after long-term administration of an opioid/hypnotic often develop delirium. To assess the nature of this phenomenon, patients in a surgical ICU following ventilatory support and sedation with an opioid/hypnotic/sedative were studied.

METHODOLOGY

Following sufentanil/midazolam (group 1; n =14) or sufentanil/propofol (group 2; n =15) sedation, patients were evaluated for changes in mean arterial blood pressure and heart rate, the activity of the central nervous system (sensory evoked potentials, spectral edge frequency of EEG), and the endogenous opioids plasma concentrations (beta-endorphin, met-enkephalin). Data obtained were correlated with the individual intensities of withdrawal symptoms 6-, 12-, and 24 h following sedation.

RESULTS

Following a mean duration of ventilation of 7.7 days (+/-3.6 SD) in groups 1 and 3.5 (+/-1.7 SD) in group 2, withdrawal intensities peaked within the 6th hour after cessation. Plasma beta-endorphin and met-enkephalin levels were low during sedation, and only the sufentanil/midazolam group demonstrated a postinhibitory overshoot. Withdrawal symptom intensities demonstrated an inverse correlation with beta-endorphin and met-enkephalin levels, a direct linear correlation with amplitude height of the evoked potential, and blood pressure and heart rate changes. Withdrawal intensities did not correlate with EEG power spectral edge frequency.

CONCLUSION

The endorphinergic system is suppressed when a potent exogenous opioid like sufentanil is given over a long period of time. Following sedation, abstinence symptoms seem to be related to postinhibitory increased endorphin synthesis. This is mostly seen in the combination of sufentanil/midazolam. In addition, an increase in the amplitude of the sensory-evoked potential suggests a postinhibitory excitatory state within the nociceptive system.

Sedation algorithm in critically ill patients without acute brain injury

OBJECTIVE

To determine whether use of a sedation algorithm to promote a high level of tolerance to the intensive care environment and preserve consciousness affected time to arousal and duration of mechanical ventilation in patients without acute brain injury.

DESIGN

Two-phase, prospective, controlled study.

SETTING

University-affiliated medical intensive care unit.

PATIENTS

: Patients without acute brain injury requiring mechanical ventilation for at least 24 hrs.

INTERVENTIONS

During the control phase, sedatives and analgesics were adjusted according to the physician's decision. During the algorithm phase, sedatives and analgesics were adjusted according to an algorithm developed by a multidisciplinary team including nurses and physicians. The algorithm was based on regular assessments of consciousness and tolerance to the intensive care unit environment using the Adaptation to Intensive Care Environment instrument and was designed to achieve tolerance and maintain a high level of consciousness. Standard practices, including weaning from the ventilator, were the same during both study phases.

MEASUREMENTS AND MAIN RESULTS

A total of 102 patients were enrolled (control group, n = 54; algorithm group, n = 48). Median duration of mechanical ventilation was significantly shorter in the algorithm group (4.4 days [interquartile range, 2.1-9.8]) compared with the control group (10.3 days [3.5-17.2], p = .014), representing a 57.3% reduction. In Cox multivariate analysis, the risk of remaining on mechanical ventilation was 0.48 times (95% confidence interval, 0.29-0.78) lower for algorithm patients compared with controls. The median time to arousal was also significantly shorter in patients in the algorithm group (2 days [2-5]) compared with the control group (4 days [2-9], p = .006).

CONCLUSIONS

The use of a sedation algorithm to promote tolerance to the intensive care environment and preserve consciousness in patients without acute brain injury resulted in a marked decrease in the duration of mechanical ventilation. This reduction was at least partly attributable to a shorter time to arousal after initiation of mechanical ventilation.

Midazolam Therapeutic Drug Monitoring in Intensive Care Sedation

During a 5-year period, 1997 to 2002, therapeutic drug monitoring of midazolam plasma concentrations in combination with the level of sedation as assessed by the Ramsay sedation scale was performed in 648 critically ill patients requiring artificial ventilation. In a subgroup of 189 patients sepsis-related organ failure assessment procedure was additionally performed. A total number of 3354 samples were analyzed. Significantly reduced clearance of midazolam was observed within the first 4 days of midazolam treatment of critically ill patients. As a result, accumulation of midazolam and its metabolites occurred within the first week of treatment. In contrast, parameters such as serum bilirubin or creatinine, which are commonly used to adapt drug therapy to organ dysfunction, showed significant changes with a delay of more than 10 days as compared with the findings of midazolam monitoring. Midazolam plasma concentrations showed a good correlation with the sedative capacity of the drug (r2 = 0.906). However, a great variability of the drug effect between patients could be demonstrated, which, as a consequence, may complicate the development of dosing strategies based on midazolam plasma concentrations to better control sedation in critically ill patients. Furthermore, patient age seems to be an important factor for the considerable variability of the sedative effect of midazolam. To achieve a certain levels of sedation, significantly lower midazolam infusion rates as well as plasma concentrations were required as the patients age increased. No significant sex-related differences could be observed for any pharmacologic parameter obtained in this study. Our findings suggest that midazolam therapeutic drug monitoring might be a useful tool to individualize midazolam therapy, especially in critically ill patients developing organ dysfunction and requiring long-term sedation to minimize the risk of drug accumulation and excessive sedation.

Delirium and sedation

Critically ill patients nearing the end of life frequently present with needs for aggressive sedation and analgesia. Optimizing patient comfort while permitting effective communication are challenging goals in this patient population. This article discusses delirium and sedation as it applies to dying patients, and provides recommendations for effective management strategies to optimize the experience of such patients at the end of life.

Management of sedation in mechanically ventilated patients

PURPOSE OF REVIEW

There are many new and exciting studies in the sedation literature. Recent studies of new scoring systems to monitor sedation, new medications, and new insights into post-intensive care unit (ICU) sequelae have brought about interesting ideas for achieving an adequate level of sedation of our patients while minimizing complications.

RECENT FINDINGS

The recent literature focuses on monitoring the level of a patient's sedation with new bedside clinical scoring systems and new technology. Outcomes studies have highlighted problems with both inadequate sedation and excessive sedation in regard to patients' post-ICU psychological health. More insight into drug withdrawal and addiction as complications of ICU care were examined. A new medication for sedation in the ICU has been approved for use, but its role is not yet defined.

SUMMARY

Many patients in the ICU receive mechanical ventilation and will require sedative medications. A frequently overlooked cause of agitation in the ventilated patient is pain, and assessing the adequacy of analgesia is an important part of the continuous assessment of a patient. The goal of sedation is to provide relief while minimizing the development of drug dependency and oversedation. Careful monitoring with bedside scoring systems, the appropriate use of medications, and a strategy of daily interruption can lead to diminished time on the ventilator and in the ICU.

Arrêt de la sédation en neuroréanimation

The reasons for sedation in neurointensive care can be divided into two main groups: (i) general indications, as for other intensive care patients, such as to allow the necessary treatments (therapeutic facilitation), controlling the states of agitations em leader; (ii) specific indications due to the neuro-physiologic effect of the sedatives: facilitation of the control of the intracranial pressure and lowering of the cortical excitability during the epileptic fits and thereby helping the recovery of the cerebral tissue and diminishing the secondary brain insults. It is important to remember that sedation is usually combined with the administration of opioids, which can potentiate the effect of the sedative drugs. The interruption of the sedation can be long- or short-termed. The definitive interruption is possible once the clinical and cerebral state of the patient does not justify any sedation, whereas the brief interruption allows a neurological reassessment. The amount of literature on sedation in intensive care is opposed to the few studies on neurointensive care: in January 2003, the American Society of Intensive Care has published recommendations for this topic without mentioning the interruption of sedation in neurointensive care patients. The aim of this article is to review the literature about the effects of the interruption of the sedation in neurointensive care patients.

Comparative tolerability of sedative agents in head-injured adults

Sedative agents are widely used in the management of patients with head injury. These drugs can facilitate assisted ventilation and may provide useful reductions in cerebral oxygen demand. However, they may compromise cerebral oxygen delivery via their cardiovascular effects. In addition, individual sedative agents have specific and sometimes serious adverse effects. This review focuses on the different classes of sedative agents used in head injury, with a discussion of their role in the context of clinical pathophysiology. While there is no sedative that has all the desirable characteristics for an agent in this clinical setting, careful titration of dose, combination of agents, and a clear understanding of the pathophysiology and pharmacology of these agents will allow safe sedative administration in head injury.

Sedation in the intensive care unit

Although the administration of sedatives is a commonplace activity in the ICU, few guidelines are available to aid the clinician in this practice. The first principle of sedative administration is to define the specific problem requiring sedation and to rationally choose the drug and depth of sedation appropriate for the indication. Next, the clinician must recognize the diverse and often unpredictable effects of critical illness on drug pharmacokinetics and pharmacodynamics. Failure to recognize these effects may lead initially to inadequate sedation and subsequently to drug accumulation. Drug accumulation may result in prolonged encephalopathy and mechanical ventilation and may mask the development of neurologic or intra-abdominal complications. Daily interruption of continuous sedative infusions is a simple and effective way of addressing this problem. A glossary of sedative drugs commonly used in the ICU is included in this review.

[Sedation induced by midazolam in intensive care: pharmacologic and pharmacokinetic aspects]

OBJECTIVE

Review on midazolam in order to optimize drug utilisation and therapeutic monitoring.

DATA SOURCES

Research of English or French articles published until August 2001, using Medline database. The key words were: midazolam, pharmacokinetics, pharmacodynamic, sedation, drug interaction.

STUDY SELECTION

Original articles, clinical cases and letters to the Editor were selected. Animal studies were excluded.

DATA EXTRACTION

The articles were analysed according to their interest in midazolam clinical practice.

DATA SYNTHESIS

Midazolam is a benzodiazepine widely used in intensive care unit, as a sedative, anxiety-relieving, and amnesic drug. Midazolam could be used in patients with cardiac, or respiratory failure, and in neurosurgery. A great interindividual variability on pharmacokinetic and pharmacodynamic response was observed. In intensive care patients, elimination half-life is known to be widely increased. Midazolam is metabolised by hepatic microsomes. The major metabolite is the 1-hydroxymidazolam, which is pharmacologically active. A prolonged sedation due to an accumulation of conjugated metabolite was observed in renal failure patients. Enzymatic inductors or inhibitors could influence pharmacokinetics and pharmacodynamic effects of midazolam.

CONCLUSION

According to midazolam pharmacokinetic and pharmacodynamic variability, an individual dosage adjustment is essential for long-term sedation. Target controlled sedation could be a mean to limit the variability and to reach quickly the pharmacodynamic effect.

When midazolam fails

Significant distress is experienced by patients, families, and caregivers when a symptom or disorder, such as an agitated delirium, becomes an intractable, or a catastrophic event, such as irreversible stridor. When palliative sedation is indicated for these patients, midazolam is usually the preferred drug. In some cases, however, midazolam fails to provide adequate sedation. Two cases are presented to illustrate this phenomenon and explore the possible mechanisms underlying this lack of response. These mechanisms appear to be multifaceted. The heterogeneity of the GABA(A) receptor complex and the alterations that this complex can undergo functionally can explain, to some degree, the diversity of the physiological and pharmacological outcomes. Other factors responsible for the diversity in response may include concomitant medications, age, concurrent disease, overall health status, alcohol use, liver disease, renal disease, smoking and hormonal status. Evidence-based guidelines on alternative treatment options should midazolam fail are required. In the interim, a lower threshold for adding an alternative drug, such as phenobarbital, or substituting midazolam with another drug, such as propofol, should be considered in these circumstances.

The effect of oxygen on propofol-induced inhibition of microsomal cytochrome P450 3A4

We have shown previously that both hypoxia and propofol may inhibit the metabolism of midazolam. We now wished to see whether there was any additive or synergistic effect when they occurred together. Microsomes were incubated with 20 microns midazolam for 60 min, and propofol 0, 50, 100 or 1000 microM was added. Incubates were further subdivided so that the environment contained 0, 10, 21 or 70% oxygen. The results confirmed our earlier study showing that propofol only had a significant inhibitory effect at a concentration greater than that seen clinically (1000 microM). Anoxia was the only environment in which significant depression of the metabolism of midazolam occurred at all concentrations of propofol. This reduced it to almost zero. Post hoc analysis of the data showed that, with the greatest concentration of propofol (1000 microM), there was increasing inhibition of metabolism of midazolam with increases of oxygen from 10 to 70%.

A cost analysis of enterally administered lorazepam in the pediatric intensive care unit

OBJECTIVE

To determine the cost savings of replacing intravenous midazolam with enterally administered lorazepam in mechanically ventilated children who require long-term continuous sedation.

DESIGN

Retrospective review of patients treated according to a preestablished pediatric intensive care unit (ICU) sedation protocol.

SETTING

Twenty-six-bed pediatric ICU in a tertiary care children's hospital.

PATIENTS

The records of 30 mechanically ventilated children were analyzed. The median age was 1.5 yrs and the median weight was 8.0 kg. Patients required continuous sedation for a total of 16 days (median).

INTERVENTIONS

According to our pediatric ICU sedation protocol, midazolam infusion was continued until the hourly midazolam requirement was stable for at least 24 hrs. Thereafter, patients with a nasojejunal tube who were likely to require a minimum of three additional days of continuous sedation were transitioned from intravenous midazolam to enterally administered lorazepam. The goal in transitioning therapy was to titrate the lorazepam dose and reduce midazolam administration while maintaining an unchanged level of sedation.

MEASUREMENTS AND MAIN RESULTS

The rate of midazolam administration was significantly (p<.05) reduced beginning on day 1 of lorazepam treatment. Midazolam was successfully discontinued in 24 (80%) patients in 3 days (median), and adequate and appropriate sedation was maintained with lorazepam monotherapy. Six patients in whom midazolam could not be discontinued experienced a 52% reduction in the rate of midazolam administration as a result of adding lorazepam. Total projected midazolam utilization was defined as the sum of midazolam administration before initiating lorazepam and the projected midazolam requirement after initiating lorazepam. Projected midazolam cost was calculated as the product of total projected midazolam utilization and midazolam acquisition cost. Actual expenditures for both midazolam and lorazepam were subtracted from the projected midazolam cost to calculate the estimated cost savings. Overall, midazolam utilization (in milligrams) was reduced by 46.7+/-27.6% (median 52). Total projected midazolam cost for the 30 patients was $90,771. The actual cost of midazolam and lorazepam combined was $47,867, resulting in a cost savings of $42,904.

CONCLUSIONS

Transitioning from intravenous midazolam to enterally administered lorazepam in critically ill children who require long-term sedation results in significant cost savings. The oral formulation of lorazepam was convenient to use, inexpensive, and effective in maintaining a continuous and appropriate level of sedation once midazolam was discontinued.

Propofol versus midazolam: safety and efficacy for sedating the severe trauma patient

Previous studies have compared sedation profiles with midazolam (Mz) and propofol (Pf), particularly in heterogeneous populations of patients. Decreases in blood pressure and heart rate have been reported after the administration of propofol. These side effects are potentially deleterious in severe trauma patients, particularly in patients with head trauma. To assess the safety and efficacy of Mz and Pf, alone or in combination, in the prolonged sedation of severe trauma patients, we designed a prospective, controlled, randomized, study. One hundred consecutively admitted trauma patients requiring mechanical ventilation and sedation for more than 48 h were studied. Patients were sedated according to three different protocols based on the continuous i.v. administration of Mz alone, Pf alone, and Mz in combination with Pf. All patients received morphine chloride. Safety and efficacy were assessed during the sedation and wake-up periods according to clinical and laboratory variables. Cerebral hemodynamics were also studied in patients with head trauma. Patients were sedated for 6.3 +/- 4.0 days (mean +/- SD). All three sedation regimens were equally efficacious in achieving the desired sedation goal. The incidence of adverse events during the sedation period was also similar. In head trauma patients with intracranial pressure (ICP) monitoring, we did not find differences in ICP, cerebral perfusion pressure, or jugular venous oxygen saturation among the three groups. The serum triglyceride concentration was significantly higher in the Pf group. Wake-up time was significantly shorter in the Pf group. We conclude that both Mz and Pf are safe and efficacious in the sedation of severe trauma patients. The use of Pf in these patients is associated with a high incidence of hypertriglyceridemia and a shorter wake-up time.

IMPLICATIONS

In a prospective, controlled, randomized study, we confirmed the safety and efficacy of midazolam and propofol, alone or in combination, in the prolonged sedation of a homogeneous group of severe trauma patients, particularly in patients with head trauma. The propofol group had shorter wake-up times and higher triglyceride levels.

Synergistic sedation with propofol and midazolam in intensive care patients after coronary artery bypass grafting

OBJECTIVES

To evaluate and compare the clinical efficacy, impact on hemodynamics, safety profiles, and cost of combined administration of propofol and midazolam (synergistic sedation) vs. midazolam and propofol administered as sole agents, for sedation of mechanically ventilated patients after coronary artery bypass grafting.

DESIGN

Prospective, controlled, randomized, double-blind clinical trial.

SETTING

Intensive care unit of SCIAS-Hospital de Barcelona.

PATIENTS

Seventy-five mechanically ventilated patients who underwent coronary artery bypass graft surgery under low-dose opioid anesthesia.

INTERVENTIONS

According to the double-blind method, patients were randomly assigned to receive propofol (n = 25), midazolam (n = 25), or propofol combined with midazolam (n = 25). Infusion rates were adjusted to stay between 8 and 11 points on Glasgow Coma Score modified by Cook and Palma.

MEASUREMENTS AND MAIN RESULTS

Mean +/- SD duration of sedation was 14.4 +/- 1.5 hrs, 14.1 +/- 1.1 hrs, and 14.7 +/- 1.9 hrs for the propofol, midazolam, and synergistic groups, respectively. The induction dose was 0.55 +/- 0.05 mg/kg for propofol as sole agent, 0.05 +/- 0.01 mg/kg for midazolam as sole agent, and 0.22 +/- 0.03 mg/kg for propofol administered in combination with 0.02 +/- 0.00 mg/kg of midazolam (p = .001). The maintenance dose was 1.20 +/- 0.03 mg/kg/hr for propofol as sole agent, 0.08 +/- 0.01 mg/kg/hr for midazolam as sole agent, and 0.50 +/- 0.09 mg/kg/hr for propofol administered in combination with 0.03 +/- 0.01 mg/kg/hr of midazolam (p < .001). All sedative regimens achieved similar efficacy in percentage of hours of adequate sedation (93% for propofol, 88% for midazolam, and 90% for the synergistic group, respectively). After induction, both propofol and midazolam groups had significant decreases in systolic blood pressure, diastolic blood pressure, left atrial pressure, and heart rate. Patients in the synergistic group had significant bradycardia throughout the study, without impairment in other hemodynamic parameters. Patients sedated with propofol or synergistic regimen awoke sooner and could be extubated before those patients sedated with midazolam (0.9 +/- 0.3 hrs and 1.2 +/- 0.6 hrs vs. 2.3 +/- 0.8 hrs, respectively, p = .01). Synergistic sedation produced cost savings of 28% with respect to midazolam and 68% with respect to propofol.

CONCLUSIONS

In the study conditions, the new synergistic treatment with propofol and midazolam administered together is an effective and safe alternative for sedation, with some advantages over the conventional regimen with propofol or midazolam administered as sole agents, such as absence of hemodynamic impairment, >68% reduction in maintenance dose, and lower pharmaceutical cost.

Complications of sedation with midazolam in the intensive care unit and a comparison with other sedative regimens

OBJECTIVE

To describe the various complications that have been reported with use of midazolam for sedation in the intensive care unit (ICU).

DATA SOURCES

Publications in scientific literature.

DATA EXTRACTION

Computer search of the literature.

SYNTHESIS

Sedation is required in the ICU in order for patients to tolerate noxious stimuli, particularly mechanical ventilation. Under- and oversedation can lead to complications. To sedate patients in the ICU, midazolam is commonly administered via titrated, continuous infusions. Cardiorespiratory effects tend to be minimal; however, hypotension can occur in hypovolemic patients. Prolonged sedation after cessation of the midazolam infusion may be caused by altered kinetics of the drug in critically ill patients or by accumulation of active metabolites. In addition, paradoxical and psychotic reactions have been rarely reported. Tolerance and tachyphylaxis may occur, particularly with longer-term infusions (> or = 3 days). Benzodiazepine withdrawal syndrome has also been associated with high dose/long-term midazolam infusions. Compared with propofol infusions, midazolam infusions have been associated with a decreased occurrence of hypotension but a more variable time course for recovery of function after the cessation of the infusion. Lorazepam is a more cost-effective choice for long-term (> 24 hrs) sedation.

CONCLUSION

Continuous infusion midazolam provides effective sedation in the ICU with few complications overall, especially when the dose is titrated.

Pharmacokinetics of drugs used in critically ill adults

Critically ill patients exhibit a range of organ dysfunctions and often require treatment with a variety of drugs including sedatives, analgesics, neuromuscular blockers, antimicrobials, inotropes and gastric acid suppressants. Understanding how organ dysfunction can alter the pharmacokinetics of drugs is a vital aspect of therapy in this patient group. Many drugs will need to be given intravenously because of gastrointestinal failure. For those occasions on which the oral route is possible, bioavailability may be altered by hypomotility, changes in gastrointestinal pH and enteral feeding. Hepatic and renal dysfunction are the primary determinants of drug clearance, and hence of steady-state drug concentrations, and of efficacy and toxicity in the individual patient. Oxidative metabolism is the main clearance mechanism for many drugs and there is increasing recognition of the importance of decreased activity of the hepatic cytochrome P450 system in critically ill patients. Renal failure is equally important with both filtration and secretion clearance mechanisms being required for the removal of parent drugs and their active metabolites. Changes in the steady-state volume of distribution are often secondary to renal failure and may lower the effective drug concentrations in the body. Failure of the central nervous system, muscle, the endothelial system and endocrine system may also affect the pharmacokinetics of specific drugs. Time-dependency of alterations in pharmacokinetic parameters is well documented for some drugs. Understanding the underlying pathophysiology in the critically ill and applying pharmacokinetic principles in selection of drug and dose regimen is, therefore, crucial to optimising the pharmacodynamic response and outcome.

Pharmacokinetics and pharmacodynamics of sedatives and analgesics in the treatment of agitated critically ill patients

The pharmacokinetics and pharmacodynamics of sedatives and analgesics are significantly altered in the critically ill. These changes may account for the large differences in drug dosage requirements compared with other patient populations. Drugs that in other settings may be considered short-acting often have significantly altered onset and duration of action in critically ill patients, necessitating a change in dosage. Of the benzodiazepines, lorazepam is the drug whose parameters are the least likely to be altered in critical illness. The presence of active metabolites with other benzodiazepines complicates their use during periods of prolonged use. Similarly, the presence of active metabolites of morphine and pethidine (meperidine) warrants caution in patients with renal insufficiency. The fewer cardiovascular effects seen with high-potency opioids, such as fentanyl and sufentanil, increase their usefulness in haemodynamically compromised patients. The pharmacodynamics of propofol are not significantly altered in the critically ill. Ketamine should be used with a benzodiazepine to prevent the emergence of psychomimetic reactions. Lower sedative doses of benzodiazepines and anaesthetics may not provide reliable amnesia. Barbiturates and propofol probably do not induce hyperalgesia and lack intrinsic analgesic activity. The antipsychotic agent haloperidol has a calming effect on patients and administration to the point of sedation is generally not necessary. Combinations of sedatives and analgesics are synergistic in producing sedation. The costs of sedation and analgesia are very variable and closely linked to the pharmacokinetics and pharmacodynamics of the drug. Monitoring of sedation and analgesia is difficult in uncooperative patients in the intensive care unit. In the future, specific monitoring tools may assist clinicians in the regulation of infusions of sedative and analgesic agents.

Propofol or midazolam for sedation and early extubation following cardiac surgery

PURPOSE

The purpose of this randomized, double-blind study was to evaluate the efficacy of midazolam and propofol for postoperative sedation and early extubation following cardiac surgery.

METHODS

ASA physical status II-III patients scheduled to undergo elective first-time cardiac surgery with an ejection fraction > 45% were eligible. All patients received a standardized sufentanil/isoflurane anaesthesia. During cardiopulmonary bypass 100 micrograms.kg-1.min-1 propofol was substituted for isoflurane. Upon arrival in the Intensive Care Unit (ICU), patients were randomized to either 10 micrograms.kg-1.min-1 propofol (n = 21) or 0.25 microgram.kg-1.min-1 midazolam (n = 20). Infusion rates were adjusted to maintain sedation within a predetermined range (Ramsay 2-4). The infusion was terminated after four hours. Patients were weaned from mechanical ventilation and their tracheas extubated when Haemodynamic stability, haemostasis, normothermia and mental orientation were confirmed. Haemodynamic measurements, arterial blood gas tensions and pulmonary function tests were recorded at specified times.

RESULTS

There were no differences between the two groups for the time spent at each level of sedation, number of infusion rate adjustments, amount of analgesic and vasoactive drugs, times to awakening and extubation. The costs of propofol were higher than those of midazolam. There were no differences in haemodynamic values, arterial blood gas tensions and pulmonary function.

CONCLUSION

We conclude that midazolam and propofol are safe and effective sedative agents permitting early extubation in this selected cardiac patient population but propofol costs were higher.

A method to produce sedation in critically ill patients

OBJECTIVE

To evaluate a protocol based on continuous infusion of a benzodiazepine and morphine to produce apnea/decreased respiratory effort as an adjunct to complex mechanical ventilation in patients with respiratory failure.

DESIGN

Observational report of consecutive patients.

SETTING

University medical intensive care unit.

PATIENTS

Seventeen consecutive patients with acute respiratory failure requiring high levels of sedation and/or paralysis to facilitate mechanical ventilation were studied.

INTERVENTIONS

Patients were started on a continuous infusion of a benzodiazepine and morphine soon after mechanical ventilation was instituted. The dosages of the benzodiazepine and morphine were increased to the end point of diminished respiratory effort or apnea depending on the clinical status of the patient and ventilatory mode. This regimen was supplemented with single doses of neuromuscular blocking agents (NMBAs) only as the dosages of benzodiazepine/narcotic were being titrated. The benzodiazepine/narcotic agents were then gradually reduced as the patient's condition improved, often using an oral route of administration.

MEASUREMENTS AND RESULTS

The benzodiazepine/morphine combination produced apnea and diminished respiratory effort in patients requiring sedation from 2 to 50 days, including those with hemodynamic instability, hepatic dysfunction, renal dysfunction, and sepsis. The combination allowed the use of NMBAs to be minimized. There was no evidence of worsened hemodynamic instability as a result of the administration of these agents. The gastrointestinal tract could be used for nutrition in 8 of the 17 patients.

CONCLUSIONS

Continuous infusion of a benzodiazepine and morphine controlled the respiratory rate in patients with severe respiratory failure requiring complex mechanical ventilatory support.

Comparative study of propofol versus midazolam in the sedation of critically ill patients: results of a prospective, randomized, multicenter trial

OBJECTIVES

To compare the effectiveness, characteristics, duration of action, hemodynamic and biochemical effects, and side effects of propofol and midazolam used for continuous intravenous sedation of ventilated critically ill patients.

DESIGN

Multicenter, prospective, randomized, nonblinded study.

SETTING

Nine Spanish general intensive care units (ICUs).

PATIENTS

Ninety-eight patients admitted to the ICU who were mechanically ventilated and required sedation for a minimum of 48 hrs.

INTERVENTIONS

Propofol or midazolam was used for induction and maintenance of continuous intravenous sedation for a maximum of 5 days. The effectiveness of those two regimens was assessed according to their effects on ventilatory management and the presence of agitation.

MEASUREMENTS AND MAIN RESULTS

In 93% of the patients studied, there was a medical cause necessitating mechanical ventilation. The mean (+/-SD) duration of sedation was 81 +/- 25 hrs and 88 +/- 27 hrs for the propofol and midazolam groups, respectively. The induction dose was 2.24 +/- 0.43 mg/kg over 318 +/- 363 secs for propofol, and 0.22 +/-0.07 mg/kg over 33 +/-29 secs for midazolam. The maintenance dose was 2.8 +/-1.1 mg/kg/hr for propofol and 0.14 +/- 0.10 mg/kg/hr for midazolam. There was no difference regarding the opiate and muscle relaxant requirements between the two groups. Sedation with propofol was more effective in achieving patient-ventilator synchrony than that with midazolam after the first hour of treatment (p < .01). Patients sedated with propofol awoke more rapidly and with less variability that those patients sedated with midazolam (23 +/- 16 mins vs. 137 +/- 185 mins, respectively, p < .05), particularly in those patients requiring deep sedation (27 +/- 16 mins vs. 237 +/- 222 mins, respectively, p < .01). No hemodynamic or biochemical changes were detected in any of the treatment groups. During induction, five patients in the propofol group and two patients in the midazolam group had hypotension.

CONCLUSIONS

In this population of critically ill patients, propofol is an effective and safe alternative for sedation, with some advantages, such as short duration of action and high effectiveness over the conventional regimen with benzodiazepines and opiates.

Pharmacokinetics and pharmacodynamics of propofol/alfentanil infusions for sedation in ICU patients

OBJECTIVE

Population pharmacokinetic analysis and pharmacodynamic profile of propofol/alfentanil infusions for sedation and analgesia of intensive care unit patients for up to 24 h.

DESIGN

Institutional Review Board-approved prospective clinical trial.

SETTING

The ten-bed intensive care unit of an university hospital.

PATIENTS

18 consecutive patients (ten men/eight women; age: 17-73 years, mean 51.6 +/- 16.7 years, SD; body weight: 60-110 kg, mean 82.9 +/- 11.2 kg, SD) requiring mechanical ventilation and prolonged sedation/analgesia after major surgery or trauma.

INTERVENTIONS

Plasma propofol and alfentanil concentrations were measured at regular intervals during the long-term drug infusion using a high-performance liquid chromatography (propofol) and radioimmunoassay (alfentanil) analysis. The depth of sedation was controlled by monitoring a two-lead online EEG. Thus, drug application was computer controlled via a closed-loop EEG median-frequency feedback system.

RESULTS

ICU long-term infusion population pharmacokinetics (open three-compartment model) revealed for propofol: central compartment distribution volume (V1): 31.2 +/- 5.3 l; steady-state distribution volume (Vdss): 499 +/- 173 l; total clearance (Cltot): 1001- +/- 150 ml/min; redistribution half-life (t1/2 gamma): 90 +/- 23 min; elimination half-life (t1/2 beta): 558 +/- 218 minutes. For alfentanil: V1: 31.9 +/- 10.1 l; Vdss: 124 +/- 41 l; Cltot: 345 +/- 70 ml/min; t1/2 gamma: 36 +/- 15 min; t1/2 beta: 275 +/- 94 min, respectively.

CONCLUSIONS

The population pharmacokinetic analysis of propofol/alfentanil for ICU sedation therapy revealed increased volumes of drug distribution and decreased elimination characteristics as compared to pharmacokinetic data from short-term infusions in surgical patients. This can be attributed in part to altered distribution/redistribution processes and/or drug elimination under the condition of ICU therapy. No significant drug accumulation was observed. For future long-term sedation and analgesia of ICU patients with propofol/alfentanil, this altered pharmacokinetic behaviour should be taken into consideration to allow a more individualized and safer dosing of this drug combination.

Sedation for the critically ill neurologic patient

OBJECTIVE

To review the scientific basis for sedation of critically ill neurologic patients by summarizing the distinct neurophysiologic disturbances present in this population and presenting the central nervous system effects of sedative agents to permit optimal drug therapy.

DATA SOURCES

Review of the English language clinical and scientific literature using MEDline data search.

STUDY SELECTION

Literature references were selected through a key word search of sedative therapy, drugs used for sedation, and specific neurologic disorders and processes to provide an in-depth overview of sedative drug mechanisms of action, effects on neurophysiology and intracranial dynamics, pharmacokinetics, and toxicity profile. Special emphasis was placed on neurologic side effects.

DATA EXTRACTION

Clinical and scientific literature was reviewed and data relevant to neurophysiologic effects of sedative drug therapy were summarized. Recommendations for institution of sedative therapy and of particular agents were made as a result of analysis of all pooled data.

DATA SYNTHESIS

Critically ill patients with neurologic pathology present as a unique subset of individuals cared for in an acute care setting. Because monitoring of neurologic patients requires frequent assessment of the neurologic examination, the goal of sedative therapy should be to enhance, or to minimally perturb elicitation of the examination. Neurophysiologic disturbances introduce distinct risks for sedation and require their identification and understanding before the initiation of any sedative therapy. Sedative drugs, in particular, act to disturb central nervous system function and their effects may result in diagnostic confusion and further neurologic deterioration. The pharmacokinetic and neurophysiologic actions of the common classes of sedative agents, such as benzodiazepines, opioids, barbiturates, and neuroleptics, as well as ketamine, propofol, and clonidine are discussed. Recommendations are presented based on the specific type of sedation required and the underlying neurologic disturbance. Several specific examples, including head trauma, neuromuscular disease, and alcohol withdrawal, are provided.

CONCLUSIONS

Preservation of the neurologic examination is paramount in documenting clinical improvement or deterioration in the critically ill neurologic patient. Pharmacologic sedation in this unique population of acute care patients requires careful consideration of the underlying neurophysiologic disturbances and potential adverse effects introduced by sedative drugs.

The role of flumazenil in the critically ill

Flumazenil is a specific benzodiazepine antagonist. It competitively inhibits the action of benzodiazepines at gamma aminobutyric acid (GABA) receptors in the central nervous system and thus reverses the sedative effects of benzodiazepines. Usually, it is given intravenously as a bolus dose or as an infusion. It has a short duration of action. Flumazenil is extensively metabolized to compounds that have minimal benzodiazepine antagonistic properties. Reversal of sedation can be useful in many conditions that are often encountered in the critically ill. The adverse effects of its use are usually predictable and, with sufficient clinical monitoring, are usually avoidable. These properties make it a useful and safe drug when used appropriately.

The effect of supplemental dietary fat on plasma cholesterol levels in lovastatin-treated hypercholesterolemic patients

STUDY OBJECTIVE

A validation study was conducted first to test assumptions about the effect of saturated and unsaturated dietary fat supplements. The second study was conducted to determine the effect on blood cholesterol levels of saturated and unsaturated fat supplements in patients who followed a low-fat diet and were administered lovastatin.

DESIGN

Randomized, crossover design, with three periods in the first study and four in the second study, each lasting 6 weeks.

SETTING

Cholesterol Research Center.

PATIENTS

The first study evaluated adults with total cholesterol levels between 200 and 280 mg/dl (5.172 and 7.241 mmol/L). The second study included adults with low-density lipoprotein (LDL) cholesterol levels above 160 mg/dl (4.138 mmol/L).

INTERVENTIONS

Fat supplements with either coconut or canola oil were delivered to patients in oatmeal-raisin cookies.

MEASUREMENTS AND MAIN RESULTS

In the validation study, patients' mean prerandomization total cholesterol level of 222 mg/dl was reduced to 213 mg/dl with canola oil and increased to 233 mg/dl with coconut oil cookies (p = 0.0038). In the second study the mean prerandomization total cholesterol level of 214 mg/dl was decreased to 199 mg/dl with canola oil and to 208 mg/dl with coconut oil cookies (p = 0.2342). The LDL cholesterol levels changed in a similar fashion in both studies.

CONCLUSIONS

Changes in total and LDL cholesterol levels in the validation study were expected based on established effects of saturated and unsaturated fatty acids, but changes in these levels in lovastatin-cookie study were not expected. They could have occurred because lovastatin reversed the effect of saturated fats and enhanced the effect of unsaturated fats. Alternatively, they may have been due to enhanced bioavailability of lovastatin when administered with a high-fat diet. These findings must be confirmed.

Severe withdrawal syndrome possibly associated with cessation of a midazolam and fentanyl infusion

A 40-month-old child was sedated with a fentanyl and midazolam infusion for 7 days. After the drugs were discontinued he became unresponsive and globally aphasic, and had marked thrombocytosis. He was hospitalized for 4 weeks, during which time his motor and cognitive status slowly improved, and had almost returned to baseline at time of discharge. Severe neurologic abnormalities have been reported with midazolam and fentanyl, administered separately or together, and seem to be a consequence of a withdrawal syndrome. Of interest, this patient had a reactive thrombocytosis at the time of onset of the withdrawal syndrome, and his decreased platelet count coincided with the return to normal cognitive and motor status. Based on this experience and other reports, we believe midazolam-fentanyl combination should be administered with caution.

Prolonged sedation due to accumulation of conjugated metabolites of midazolam

Midazolam is a short-acting benzodiazepine routinely used in intensive-care medicine. Conjugates of its main metabolite, alpha-hydroxymidazolam, have been shown to accumulate in renal failure but have not previously been related to the prolonged sedative effects commonly observed in critically ill patients. We report five patients with severe renal failure who had prolonged sedation after administration of midazolam. In all five patients, the comatose state was immediately reversed by the benzodiazepine-receptor antagonist flumazenil. Serum concentration monitoring showed high concentrations of conjugated alpha-hydroxymidazolam when concentrations of the unconjugated metabolite and the parent drug were below the therapeutic range. In-vitro binding studies showed that the affinity of binding to the cerebral benzodiazepine receptor of glucuronidated alpha-hydroxymidazolam was only about ten times weaker (affinity constant 16 nmol/L) than that of midazolam (1.4 nmol/L) or unconjugated alpha-hydroxymidazolam (2.2 nmol/L). Conjugated metabolites of midazolam have substantial pharmacological activity. Physicians should be aware that these metabolites can accumulate in patients with renal failure.

A pharmacokinetic interaction between roxithromycin and midazolam

The interaction between roxithromycin and midazolam was investigated in a double-blind, randomised crossover study of two phases. Ten healthy volunteers were given roxithromycin (300 mg) or placebo once daily for 6 days. On the sixth day they ingested 15 mg midazolam. Plasma samples were collected and psychomotor performance measured for 17 h. Roxithromycin administration significantly increased the area under the plasma midazolam concentration-time curve from 8.3 to 12.2 micrograms.ml-1.min and the elimination half-lives from 1.7 to 2.2 h. In psychomotor performance only minor differences were seen between the treatments in one of the measured psychomotor parameters. Thus, in contrast to the strong interaction between erythromycin and midazolam, the interaction between roxithromycin and midazolam appears less likely to be clinically significant.

Pharmacokinetics and pharmacodynamics in the critically ill patient

1. Until recently, when drugs were used in critically ill patients they were expected to behave in the same way as in less seriously ill patients. Now the unpredictability of even the most reliable drugs has been recognized. With this there is an awareness of the adverse effects drugs may have on organs other than the ones the drug was intended to act on. In patients with multiorgan dysfunction, poly-pharmacy is usually needed. The drugs may not only interfere with the action of each other at the receptor and enzyme level, but may also change protein binding and elimination. All these effects may be unimportant in less seriously ill patients, but may affect outcome in the critically ill. A high degree of awareness and suspicion of unknown drug-induced adverse reaction is needed by clinicians and pharmacologists alike.

The effects of midazolam on the EEG during sedation of critically ill patients

Patients who require mechanical ventilation are often sedated with midazolam. As clinical signs of sedation are often confusing or nonexistent, and there are few adverse side effects when large doses are infused over a period of days, substantial drug accumulation can result in these critically ill patients, despite the short half-life of midazolam. An objective monitor of sedation would help maintain sedation at a constant level despite changing pharmacokinetic values in patients. We undertook this study to describe the electroencephalographic changes which occur with intravenous midazolam in critically ill patients, and to determine if a relationship exists between these changes and the depth of sedation as measured using a clinical scoring method. A series of 31 critically ill patients who required intravenous midazolam during mechanical ventilation were studied. Four different levels of sedation were defined ranging from execution of verbal commands to no response to suctioning through the tracheal tube or sternal rub. Electroencephalographic recordings were obtained in patients on a daily basis and a concurrent sedation level was determined. High frequency electroencephalogram activity decreased as sedation level increased. This was reflected in decreases in the spectral edge (17.61 to 10.56 Hz (p = 0.0024)), the median frequency (4.27 to 2.56 Hz (p = 0.0278)), and the logarithm of the absolute power in the beta 1 (p = 0.0012), and beta 2 (p < 0.0001) bands. An incidental finding of asymmetry in power between right and left frontal electrodes was observed, with right-sided power being 9-18% greater (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Propofol vs midazolam in short-, medium-, and long-term sedation of critically ill patients. A cost-benefit analysis

The purpose of this study was to evaluate and compare the clinical effects, safety, and economic cost of propofol and midazolam in the sedation of patients undergoing mechanical ventilation in the ICU. Eighty-eight critically ill patients were studied and randomly allocated to receive short-term (less than 24 h), medium-term (24 h to 7 days), and prolonged (more than 7 days) continuous sedation with propofol (n = 46) or midazolam (n = 42). Mean doses required were 2.36 mg/kg/h for propofol and 0.17 mg/kg/h for midazolam. Patients in the group receiving propofol showed a percentage of hours of sedation at the desired level (grade 2, 3, 4, or 5 on the Ramsay scale) of 93 percent, compared with 82 percent (p < 0.05) in the group receiving midazolam. Both agents were considered safe with respect to the induction of adverse reactions during their use in prolonged sedation. Recovery after interrupting sedation was significantly faster in patients treated with propofol than in those sedated with midazolam (p < 0.05). Recovery of total consciousness was predictable according to sedation time in propofol-treated subgroups (r = 0.98, 0.88, and 0.92, respectively), while this correlation was not observed in the midazolam-treated group. In the subgroup with sedation of less than 24 h, propofol provided a cost savings of approximately 2,000 pesetas (pts) per patient, due to shorter stays in the ICU. We conclude that propofol is a sedative agent with the same safety, higher clinical effectiveness, and a better cost-benefit ratio than midazolam in the continuous sedation of critically ill patients.