Propofol 2% in critically ill patients: effect on lipids

Evaluation of Hypertriglyceridemia in Critically Ill Patients With Coronavirus Disease 2019 Receiving Propofol

Objectives

To report the prevalence of, and evaluate risk factors for, the development of hypertriglyceridemia (defined as a serum triglyceride level of > 400 mg/dL) in patients with coronavirus disease 2019 who received propofol.

Design

Single-center, retrospective, observational analysis.

Setting

Brigham and Women's Hospital, a tertiary academic medical center in Boston, MA.

Patients

All ICU patients who with coronavirus disease 19 who received propofol between March 1, 2020, and April 20, 2020.

Interventions

None.

Measurements and Main Results

The major outcome of this analysis was to report the prevalence of, and risk factors for, the development of hypertriglyceridemia in patients with coronavirus disease 19 who received propofol. Minor outcomes included the development of acute pancreatitis and description of propofol metrics. Of the 106 patients that were included, 60 (56.6%) developed hypertriglyceridemia, with a median time to development of 46 hours. A total of five patients had clinical suspicion of acute pancreatitis, with one patient having confirmatory imaging. There was no difference in the dose or duration of propofol in patients who developed hypertriglyceridemia compared with those who did not. In the patients who developed hypertriglyceridemia, 35 patients (58.5%) continued receiving propofol for a median duration of 105 hours. Patients who developed hypertriglyceridemia had elevated levels of inflammatory markers.

Conclusions

Hypertriglyceridemia was commonly observed in critically ill patients with coronavirus disease 2019 who received propofol. Neither the cumulative dose nor duration of propofol were identified as a risk factor for the development of hypertriglyceridemia. Due to the incidence of hypertriglyceridemia in this patient population, monitoring of serum triglyceride levels should be done frequently in patients who require more than 24 hours of propofol. Many patients who developed hypertriglyceridemia were able to continue propofol in our analysis after reducing the dose.

The Incidence of Propofol-Induced Hypertriglyceridemia and Identification of Associated Risk Factors

Supplemental Digital Content is available in the text.

Objectives:

The objective of this study was to describe the incidence of propofol-induced hypertriglyceridemia and the risk factors associated with hypertriglyceridemia in mechanically ventilated ICU patients while receiving propofol.

Design:

This was a single-center case-control study.

Setting:

Brigham and Women’s Hospital, a tertiary academic medical center in Boston, MA.

Subjects:

Adult ICU patients who received continuous infusion propofol for at least 24 hours from May 1, 2019, to December 31, 2019, were included. Patients were excluded if they were diagnosed with acute pancreatitis upon admission or did not have any serum triglyceride levels evaluated during propofol administration.

Interventions:

None.

Measurements and Main Results:

The major outcome was the incidence and risk factors associated with the development of propofol-induced hypertriglyceridemia, defined as triglyceride level greater than or equal to 400 mg/dL. Minor outcomes included the prevalence of acute pancreatitis. A hybrid multivariate logistic regression analysis was used to evaluate the relation between individual risk factors and the dependent variable of hypertriglyceridemia. During the study period, 552 patients were evaluated for inclusion, of which 136 were included in the final analysis. A total of 38 patients (27.9%) developed hypertriglyceridemia with a median time to hypertriglyceridemia of 47 hours. The only significant independent risk factor for development of hypertriglyceridemia identified was the cumulative propofol dose (odds ratio, 1.04; 95% CI, 1.01–1.08; p = 0.016). Two of the 38 hypertriglyceridemia patients (5.3%) were diagnosed with acute pancreatitis.

Conclusions:

In our analysis, approximately one third of patients developed hypertriglyceridemia with cumulative propofol dose identified as a significant predictor of the development of hypertriglyceridemia. Despite a high incidence of hypertriglyceridemia, a significant number of patients continued propofol therapy, and a relatively low prevalence of pancreatitis was observed. Future analyses are warranted to further investigate these results.

Does the type of parenteral lipids matter? A clinical hint in critical illness

BACKGROUND & AIMS

An altered lipid profile is common among intensive care unit (ICU) patients, but evidence regarding the impact of different fatty acid (FA) emulsions administered to patients requiring parenteral nutrition (PN) is scarce. This study aimed to compare the plasma triglycerides (TG) response to two types of commercial lipid emulsions: a structured mixture of long- and medium-chain triglycerides (LCT/MCT) or LCTs with n-9 FA (LCT+) in ICU patients.

METHODS

In this retrospective observational study conducted in a multidisciplinary ICU: two groups were defined by the type of emulsion used. Inclusion criteria were: consecutive patients on PN staying ≥4 days with one TG determination before commencing PN and at least one during PN. Recorded variables included energy intake, amount and type of nutritional lipids, propofol dose, glucose and protein intake, laboratory parameters, and all drugs received. Hypertriglyceridemia (hyperTG) was defined as TG >2 mmol/L.

RESULTS

The dynamic impact of the emulsion was analyzed in 187/757 patients completing the inclusion criteria (112 LCT/MCT and 75 LCT+). The demographic variables, severity indices, diagnostic categories, and outcomes did not differ between the two groups. Seventy-seven patients (41%) presented hyperTG. Both groups received similar daily energy (1604 versus 1511 kcal/day), lipids (60 versus 61 g/day), and glucose intake (233 versus 197 g/day). There was no increase of TG concentration in those receiving the LCT/MCT emulsion compared to those receiving the LCT+ emulsion (0 and 0.2 mmol/L, respectively, p < 0.05).

CONCLUSION

LCT/MCT emulsions are associated with a less pronounced increase of plasma TG levels than LCT+ emulsions.

Hypertriglyceridemia, lipemia, and elevated liver enzymes associated with prolonged propofol anesthesia for craniotomy

: Lipemic blood was noted in the surgical field by a neurosurgeon after 12.5 hours of anesthesia consisting of infusions of propofol (total dose, 14,956 mcg) and remifentanil (total dose, 25,091 mcg). For most of that time, the rate of propofol was 120-160 mcg·kg-1·min-1 and never exceeded 160 mcg·kg-1·min-1. Lipemia was confirmed by allowing a sample of the patient's blood to settle in a syringe. The triglyceride concentration was 15.8 mmol/L. There was no metabolic acidosis or other indications of propofol infusion syndrome. Postoperatively, liver enzymes were elevated (peak aspartate aminotransferase, 420 units/L) but returned to nearly normal within 5 days. The patient recovered from surgery uneventfully. Reports of intraoperative lipemia during propofol anesthesia are very rare but raise concerns about the safety of prolonged propofol infusion.

A randomized, open-label study of the safety and tolerability of fospropofol for patients requiring intubation and mechanical ventilation in the intensive care unit

BACKGROUND

Current drugs for induction and maintenance of sedation in mechanically ventilated patients in the intensive care unit have limitations. Fospropofol, a prodrug of propofol, has not been studied as a sedative in the ICU setting.

METHODS

In this randomized, open-label pilot study, patients received 1 of 3 regimens with a goal of maintaining a Ramsay Sedation Score of 2 to 5: (1) fospropofol IV infusion with a bolus and increased infusion rate for agitation events (infusion/bolus); (2) fospropofol IV infusion with an increased infusion rate for agitation events (infusion only); or (3) propofol IV infusion with an increased infusion rate for agitation events.

RESULTS

Sixty patients received study drug and were included in the safety and efficacy analyses. Because incidence rates for adverse events were similar between fospropofol groups, and because the study was not powered to determine significant differences between treatment groups for safety variables, adverse events for both fospropofol groups were combined. In the fospropofol groups, 28 out of 38 patients (74%) experienced treatment-emergent adverse events in comparison with 14 out of 22 patients (64%) in the propofol group. The most common treatment-emergent adverse events with fospropofol were procedural pain (21.1%) and nausea (13.2%). Two patients (1 each in the fospropofol infusion/bolus and the propofol groups) experienced hypotension during the study as a potential sedation-related adverse event. Mean plasma formate levels were not significantly different among groups. Patients in all 3 treatment groups maintained Ramsay Sedation Scores of 2 to 5 for >90% of the time they were sedated.

CONCLUSION

This pilot study suggests that fospropofol, administered in either an infusion/bolus or infusion-only regimen, is tolerable and effective for short-term induction and maintenance of sedation in mechanically ventilated intensive care unit patients.

[Agents for sedation and analgesia in the intensive care unit]

Sedation-analgesia for critically ill patients is usually performed with the combination of a sedative agent and an opioid. Midazolam and propofol are the agents most commonly used for sedation in ICU. The quality of the sedation is quite comparable with both agents, but pharmacokinetic properties of propofol allow a more rapid weaning process from mechanical ventilation. However, implementation of algorithms to adjust drug dosages reduces ventilator days and limits the kinetic differences between propofol and midazolam. Among the adverse events associated with propofol, propofol infusion syndrome is a rare but lethal aspect of propofol therapy. Opioids are the mainstay of analgesic therapy. They interact synergistically with hypnotics. Sufentanil, fentanyl and morphine are the most frequently used opioids. Remifentanil is an ultrashort acting opiate that does not appear to accumulate with prolonged use. The advent of remifentanil has allowed the use of analgesia-based sedation.

Propofol-induced hyperamylasaemia in a general intensive care unit

This study examined the incidence of hyperamylasaemia, in the absence of other plausible causes of pancreatic dysfunction, in intensive care unit (ICU) patients who received propofol. One-hundred-and-seventy-two consecutive patients of a general ICU who stayed for more than 24 hours were studied. Patients with a diagnosis consistent with elevated serum amylase levels at admission were excluded from the study, as were patients who had received medications known to raise serum amylase levels. Forty-four patients 53 +/- 20 years of age and median duration of ICU stay of five days (range two to 55) were eligible. Thirty of those, aged 54 +/- 21 years and median duration of ICU stay of five days (range two to 27) received continuous infusion of propofol for sedation (maximum dose 45 microg/kg/min). Of the 30 patients who received propofol, 16 (53%) developed hyperamylasaemia (125 to 466 IU/l) after two to nine days of continuous infusion. Liver and kidney function remained normal throughout the observation period. Of the 14 patients who did not receive propofol (aged 51 +/- 18 years), only two (14%) developed hyperamylasaemia, a significantly lower incidence (P = 0.021). Propofol infusion is associated with biochemical evidence of pancreatic injury. Amylase levels monitoring of propofol-sedated patients is warranted.

The relationship between sedative infusion requirements and permissive hypercapnia in critically ill, mechanically ventilated patients

OBJECTIVE

Permissive hypercapnia (PH) may result from mechanical ventilation (MV) strategies that intentionally reduce minute ventilation. Sedative doses required to tolerate PH have not been well characterized. With increased attention to lung-protective ventilation, characterization of sedative requirements with PH and determination of sedative dose changes with PH are needed.

DESIGN

Retrospective analysis.

SETTING

Tertiary care university hospital.

PATIENTS

We evaluated 124 patients randomized in a previous study to either propofol or midazolam. PH was employed in ten of 60 patients receiving propofol and 13 of 64 patients receiving midazolam.

INTERVENTIONS

We analyzed dosing of propofol and midazolam in patients undergoing PH through a retrospective analysis of an existing database on MV patients. Total sedative (propofol and midazolam) dose was recorded for the first three days of MV. Linear regression analysis (dependent variable: sedative dose) was used to analyze the following independent variables: PH, age, gender, daily sedative interruption, type of respiratory failure, presence of hepatic and/or renal failure, Acute Physiology and Chronic Health Evaluation II score, morphine dose, and Ramsay sedation score.

MEASUREMENTS AND MAIN RESULTS

Propofol dose was higher in PH patients (42.5+/-16.2 vs. 27.0+/-15.3; p=.02); Midazolam dose did not differ between PH and non-PH patients (0.05 [0.04, 0.14] vs. 0.05 [0.03, 0.07]; p=.17). By univariate linear regression analysis, propofol dose was significantly dependent on PH, age, type of respiratory failure, morphine dose, and Ramsay score, with PH (regression coefficient, 11.7; 95% confidence interval, 1.2-22.7; p=.03) and age (regression coefficient, -0.3; 95% confidence interval -0.5 to -0.08; p=.005) remaining significant by multivariate linear regression. By univariate linear regression analysis, midazolam dose was dependent on age, morphine dose, and Ramsay score, but not PH; only morphine dose (regression coefficient, 0.44; 95% confidence interval, 0.22-0.67 for a 0.1-unit increase in morphine dose; p<.001) was significant by multivariate linear regression.

CONCLUSIONS

We conclude that higher doses of propofol but not midazolam are required to sedate patients managed with PH.

Dyslipidemia in the Critically Ill

Total and HDL cholesterol levels fall at the onset of acute illness and the cholesterol levels normalize as the patient recovers. Hypocholesterolemia may predispose the critically ill patient to sepsis and adrenal failure. Early enteral nutrition and tight glycemic control accelerate the recovery of the cholesterol levels.

Propofol-Associated Hypertriglyceridemia and Pancreatitis in the Intensive Care Unit: An Analysis of Frequency and Risk Factors

STUDY OBJECTIVES

To characterize the frequency, severity, risk factors, and clinician response to propofol-associated hypertriglyceridemia and hypertriglyceridemia-associated pancreatitis.

DESIGN

Retrospective analysis.

SETTING

Medical and surgical intensive care units.

PATIENTS

One hundred fifty-nine adult intensive care patients administered propofol for 24 hours or longer and who had at least one serum triglyceride concentration.

MEASUREMENTS AND MAIN RESULTS

Patient records were reviewed to identify the frequency of hypertriglyceridemia (serum triglyceride concentration > or = 400 mg/dl) and pancreatitis (amylase concentration > or = 125 IU/L, lipase concentration > or = 60 IU/L, and abdominal computed tomography scan or clinical examination findings consistent with pancreatitis). Of the 159 patients, 29 (18%) developed hypertriglyceridemia; six (21%) of the 29 had a serum triglyceride concentration of 1000 mg/dl or greater. The median maximum serum triglyceride concentration was 696 mg/dl (range 403-1737 mg/dl). At the time when hypertriglyceridemia was detected, the median infusion rate of propofol was 50 microg/kg/minute (range 5-110 microg/kg/min). The median time from the start of propofol therapy to identification of hypertriglyceridemia was 54 hours (range 14-319 hrs). Propofol was discontinued within 24 hours of detecting the hypertriglyceridemia 84% of the time. Compared with those who did not develop hypertriglyceridemia, patients who developed hypertriglyceridemia were older, had a longer intensive care unit stay, and received propofol for a longer duration; they were also more likely to be admitted to the medical versus the surgical intensive care unit. Pancreatitis developed in three (10%) of the 29 patients with hypertriglyceridemia.

CONCLUSION

Hypertriglyceridemia and hypertriglyceridemia-associated pancreatitis are often seen in intensive care patients receiving propofol. Serum triglyceride concentrations should be routinely monitored in these patients. In addition, alternative sedation strategies should be considered when hypertriglyceridemia is detected.

Effects of short-term propofol administration on pancreatic enzymes and triglyceride levels in children

This prospective, clinical trial evaluated the effects of short-term propofol administration on triglyceride levels and serum pancreatic enzymes in children undergoing sedation for magnetic resonance imaging. Laboratory parameters of 40 children, mean age (SD; range) 67 (66; 4-178) months undergoing short-term sedation were assessed before and 4 h after having received propofol. Mean (SD) propofol loading dose was 2.2 (1.1) mg.kg(-1) followed by continuous propofol infusion of 6.9 (0.9) mg.kg(-1).h(-1). Serum lipase levels (p = 0.035) and serum triglyceride levels (p = 0.003) were raised significantly after propofol administration but remained within normal limits. No significant changes in serum pancreatic-amylase levels were seen (p = 0.127). In two (5%) children, pancreatic enzymes and in four (10%) children triglyceride levels were raised above normal limits; however, no child showed clinical symptoms of pancreatitis. We conclude that even short-term propofol administration with standard doses of propofol may have a significant effect on serum triglyceride and pancreatic enzyme levels in children.

Serum cholesterol and triglycerides: potential role in mortality prediction

The present study was performed in order to evaluate the diagnostic usefulness of serial cholesterol and triglycerides measurements in patients with severe burns. One of the main objective was to find out if these parameters are clinically relevant to determine the morbidity of a burn patient and thereby the patient's outcome. In 220 patients with thermal injuries, cholesterol and triglyceride concentrations were measured daily. Blood samples were drawn immediately upon admission and thereafter daily until patient's discharge or death. For both parameters, a characteristic course was noted: in the group of non-survivors, a decrease of cholesterol prior to death was noted, while survivors, increased prior to discharge. The time courses of both groups (survivors-non-survivors) differed statistically significantly (P=0.0068). An increase in triglycerides was observed in all non-survivors prior to death, but in the group of survivors triglycerides remained more or less unchanged. These time courses also had statistically significant differences (P=0.0004). In our 220 patients, changes in cholesterol (P<0.0001, hazard ratio 1.02) and triglycerides (P=0.0008, hazard ratio 1.01) had comparable capability to predict the severity of a burn trauma and thereby its outcome than the established parameters in the treatment of burns (total body surface area burned, age, inhalation). We consider the serial measurements of cholesterol and triglycerides as clinically relevant to assess the morbidity of a patient and thereby to estimate the patient's outcome. We think that these serial measurements provide useful information for the clinician treating patients with severe burns.

Short-term propofol infusion as an adjunct to extubation in burned children

Children who require intubation as a component of their burn management generally need heavy sedation, usually with a combination of opiate and benzodiazepine infusions with a target sensorium of light sleep. When extubation approaches, the need for sedation to prevent uncontrolled extubation can conflict with the desire to lighten sedation enough to ensure that airway protective reflexes are strong. The several hours' half-life of these medications can make this period of weaning challenging. Therefore, the hours preceding extubation are among the most difficult in which to ensure safe adequate sedation. The pharmacokinetics of propofol allow for the rapid emergence of a patient from deep sedation. We have had success with an extubation strategy using short-term propofol infusions in critically ill children. In this work, children were maintained on morphine and midazolam infusions per our unit protocol, escalating doses as required to maintain comfort. Approximately 8 hours before planned extubation, these infusions were decreased by approximately half and propofol infusion added to maintain a state of light sleep. Extubation was planned approximately 8 hours later to allow ample time for the chronically infused opiates and benzodiazepines to be metabolized down to the new steady-state level. Thirty minutes before planned extubation, propofol was stopped while morphine and midazolam infusions were maintained at the reduced level. When the children awakened from the propofol-induced state of light sleep, they were extubated while the reduced infusions of morphine and midazolam were maintained. These were subsequently weaned slowly, depending on the child's need for ongoing pain and anxiety medication, per our unit protocol to minimize the incidence of withdrawal symptoms. Data are shown in the text as mean +/- standard deviation. These 11 children (eight boys and three girls) had an average age of 6.6 +/- 5.6 years (range, 1.2-13 years), average weight of 36.9 +/- 28.7 kg (range, 9.3-95 kg), and burn size of 43 +/- 21.4% (range, 10-85%). Three children had sustained scald burns and eight had flame injuries with associated inhalation injury. They had been intubated for an average of 12.7 +/- 10.9 (range, 2-33 days). Morphine infusions immediately before the initiation of propofol averaged 0.26 +/- 0.31 mg/kg/hour (range, 0.04-1.29 mg/kg/hr) and midazolam averaged 0.15 +/- 0.16 mg/kg/hr (range, 0.06-0.65 mg/kg/hr). Morphine infusions after beginning propofol and at extubation averaged 0.16 +/- 0.16 (range, 0.04-0.65 mg/kg/hr) and midazolam averaged 0.09 +/- 0.08 mg/kg/hr (range, 0.02-0.32 mg/kg/hr). Propofol doses after initial titration during the first hour of infusion averaged 3.6 +/- 2.9 mg/kg/hr (range, 0.4-8.1 mg/kg/hr). Nine of the 11 children (82%) were successfully extubated on the first attempt. Two required reintubation for postextubation stridor 2 to 6 hours after extubation but were successfully extubated the next day after a short course of steroids, again using the same propofol technique. All were awake at extubation and went on to survive. Morphine and midazolam infusions were gradually weaned, and there were no withdrawal symptoms noted. Although prolonged (days) infusions of propofol have been associated with adverse cardiovascular complications in critically ill young children and should probably be avoided, short-term (in hours) use of the drug can facilitate smooth extubation.

Long-term sedation with propofol 60 mg ml(-1) vs. propofol 10 mg(-1) ml in critically ill, mechanically ventilated patients

BACKGROUND

Hypertriglyceridaemia is the main cause of therapeutic failure during propofol use in long-term sedated mechanically ventilated patients. Propofol 60 mg ml(-1) has been developed to reduce fat and volume load for the critically ill patient. The purpose of the study was to compare the effectiveness of sedation, achievability of effective concentrations and the effects on serum lipid concentrations of propofol 60 mg ml(-1) vs. propofol 10 mg ml(-1) for long-term sedation in critically ill patients.

METHODS

In this randomized, open, prospective study, 20 critically ill, mechanically ventilated patients who required sedation for a minimum of 48 h received propofol 60 mg ml(-1) or propofol 10 mg ml(-1) in doses as required during 2-5 days.

RESULTS

No differences between propofol 60 mg ml(-1) and propofol 10 mg ml(-1) were observed in the effectiveness of sedation using the Ramsay Sedation score and the Subjective Sedation score, nor in relation to the propofol concentrations. Between the two groups, there were no significant differences in the daily propofol dose, number of daily infusion rate adjustments or need for additional sedatives. Mean serum triglyceride concentrations were higher in the propofol 10 mg ml(-1) group compared with the propofol 60 mg ml(-1) group [5.26 (3.19) vs. 3.22 (2.05) mmol l(-1), P > 0.05][mean (SD)]. Patients in the propofol 10 mg ml(-1) group received more fat from the propofol infusion than from the propofol 60 mg ml(-1) group [53.2 (29.6) vs. 10.0 (4.7) % compared with fat from nutrition, respectively]. A significant relationship was observed between the daily total fat dose and the serum triglyceride concentration (r2 = 0.32, P < 0.001), whereas there was no significant correlation between the daily propofol dose and the serum triglyceride concentration.

CONCLUSION

Propofol 60 mg ml(-1) is a useful alternative to propofol 10 mg ml(-1) for the long-term sedation of critically ill patients. Sedation with propofol 60 mg ml(-1) reduces fat and volume load by 83%, which reduces the risk of hypertriglyceridaemia.

Propofol in a medium- and long-chain triglyceride emulsion: pharmacological characteristics and potential beneficial effects

Hypertriglyceridemia is a possible unwanted effect during long-term propofol sedation while using a formulation containing long-chain triglycerides (LCT) from soybean oil. The use of propofol formulated in a solvent consisting of medium-chain triglycerides (MCT) and LCT might reduce the risk. Because a new solvent may affect the pharmacological profile of propofol, in this prospective, randomized, controlled, and double-blinded study we compared the pharmacodynamic and kinetic characteristics of propofol diluted in MCT/LCT fat solution with those of propofol formulated in LCT fat emulsion. In addition, serum triglyceride levels were measured during and after the administration of both drugs. Thirty patients likely to require mechanical ventilation over at least 48 h were randomized to receive either propofol 2% MCT/LCT (Group 1) or propofol 2% LCT (Group 2). Infusion rates of propofol (2.34 +/- 0.83 mg. kg(-1). h(-1) in Group 1 versus 2.31 +/- 0.6 mg. kg(-1). h(-1) in Group 2), the plasma propofol concentrations during infusion (0.95 +/- 0.53 versus 0.98 +/- 0.32 micro g/mL), and the concentrations and arousal behavior after discontinuation of the drug did not show significant differences. Plasma triglyceride concentrations during sedation did not differ between the groups, whereas there was a tendency toward a more rapid triglyceride elimination in Group 1 after termination of the propofol administration.

IMPLICATIONS

Propofol diluted in an emulsion of medium- and long chain-triglycerides shows equivalent pharmacological properties during long-term sedation compared with its hitherto well known formulation containing long-chain triglycerides only. In addition, potential favorable effects on the plasma triglyceride profile could be found.

Sedation and analgesia in intensive care. Medications attenuate stress response in critical illness

The stress response to critical illness can have many deleterious effects. Appropriate use of sedation and analgesia can attenuate the stress response, alleviate pain and anxiety, and improve compliance with care. Agitation responds best to anxiolytic drugs; pain is best relieved by analgesics. A combination of these drugs can act synergistically, because most analgesics provide some degree of sedation. In select cases, neuromuscular blocking agents are required, but they should not be used without concomitant sedation and analgesia. Use of agents needs to be tailored to the needs of individual patients; indications, anticipated length of need, and underlying organ system derangements are important considerations.

Use of propofol and other nonbenzodiazepine sedatives in the intensive care unit

Sedatives continue to be used on a routine basis in critically ill patients. Although many agents are available and some approach an ideal, none are perfect. Patients require continuous reassessment of their pain and need for sedation. Pathophysiologic abnormalities that cause agitation, confusion, or delirium must be identified and treated before unilateral administration of potent sedative agents that may mask potentially lethal insufficiencies. The routine use of standardized and validated sedation scales and monitors is needed. It is hoped that reliable objective monitors of patients' level of consciousness and comfort will be forthcoming. Each sedative agent discussed in this article seems to have a place in the ICU pharmacologic armamentarium to ensure the safe and comfortable delivery of care. Etomidate is an attractive agent for short-term use to provide the rapid onset and offset of sedation in critically ill patients who are at risk for hemodynamic instability but seem to need sedation or anesthesia to perform a procedure or manipulate the airway. Ketamine administered through intramuscular injection or intravenous infusion provides quick, intense analgesia and anesthesia and allows patients to tolerate limited but painful procedures. The risk/benefit ratio associated with the use of this neuroleptic agent must be weighed carefully. Ketamine is contraindicated in patients who lack normal intracranial compliance or who have significant myocardial ischemia. Barbiturates are reserved mainly to induce coma in patients at risk for severe CNS ischemia, which frequently is associated with refractory intracranial hypertension, or in patients with status epilepticus. When administered in high doses, these drugs have prolonged sedative and depressant effects. Judicious hemodynamic monitoring is required when barbiturate coma is induced. Haloperidol is indicated in the treatment of delirium. Patients should be monitored for extrapyramidal side effects and, when they require higher doses, for potential electrocardiographic prolongation of the QT interval. Dexmedetomidine may evolve into an agent with qualities comparable with midazolam and propofol, and it may even become a drug of choice in select patients. Further study is required, however. Propofol has many of the qualities of an ideal sedative agent. Benzodiazepines and narcotics often are used in concert with propofol to provide reliable amnesia and to relieve pain, respectively. Propofol frequently causes hypotension when administered as a bolus or infusion, particularly in patients with limited cardiac reserve or hypovolemia. More data must be obtained to identify potential deleterious effects of hypertriglyceridemia, and further evaluation of the potential benefits in certain patient populations, such as neurosurgical patients, is needed.

Effects of postoperative sedation with propofol and midazolam on pancreatic function assessed by pancreatitis-associated protein

This prospective randomised controlled study evaluated the effects of postoperative sedation with propofol and midazolam on pancreatic function. We studied 42 intensive care unit patients undergoing elective major surgery who were expected to be sedated postoperatively. Patients were randomly assigned to a propofol group (n = 21) or a midazolam group (n = 21). To assess pancreatic function, the following parameters were measured: pancreatitis-associated protein, amylase, lipase, cholesterol and triglyceride prior to start of sedation on the intensive care unit, 4 h after the sedation was started and at the first postoperative day. Patients in the propofol group received on average (SD) 1292 (430) mg propofol and were sedated for 9.03 (4.26) h. The midazolam group received 92 (36) mg midazolam and were sedated for 8.81 (4.68) h. Plasma cholesterol concentrations did not differ significantly between groups. Triglyceride plasma levels 4 h after the start of infusion were significantly higher in the propofol group (140 (54) mg.dl(-1)) than the midazolam-treated patients (81 (29) mg.dl(-1)), but were within normal limits. There were no significant differences between the two groups regarding amylase, lipase and pancreatitis-associated protein plasma concentrations at any time. No markers of pancreatic dysfunction were outside the normal range. We conclude that postoperative sedation with propofol induced a significant increase of serum triglyceride levels but that pancreatic function is unchanged with standard doses of propofol.

The immunomodulatory effects of prolonged intravenous infusion of propofol versus midazolam in critically ill surgical patients

Both propofol and midazolam are known to inhibit immune function. The aim of this study was to investigate cytokine production in critically ill surgical patients as early markers of immune response to prolonged infusion of propofol and midazolam. The study enrolled 40 elective patients who were to receive long-term sedation for more than 2 days. Patients were randomly allocated to one of two equally sized groups. Central venous blood samples for measurement of interleukin-1beta (IL-1beta), interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-8 (IL-8), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were drawn prior to the start and after 48 h of infusion. After 48 h, propofol caused significant increases in IL-1beta (24%), IL-6 (23%) and TNF-alpha (4.8 times) levels, while midazolam caused significant decreases in IL-1beta (21%), IL-6 (21%) and TNF-alpha (19%). Both agents caused significant decreases in IL-8 levels (propofol: 30%, midazolam: 48%, p < 0.05). Propofol caused significant decreases in IL-2 levels (68%, p < 0.001) but increases in IFN-gamma (30%, p < 0.05), whereas there was no significant change with midazolam compared with the pre-infusion level. In conclusion, during 48 h of continuous infusion, propofol stimulated, while midazolam suppressed, the production of the pro-inflammatory cytokines IL-1beta, IL-6 and TNF-alpha, and both caused suppression of IL-8 production. Propofol inhibited IL-2 production and stimulated IFN-gamma production, whereas midazolam failed to do so. Therefore, sedative agents may have clinical implications in high-risk and immunocompromised patients.