Effects of remifentanil and alfentanil on seizure duration, stimulus amplitudes and recovery parameters during ECT

BACKGROUND AND OBJECTIVE

Propofol may decrease seizure duration in electroconvulsive therapy. Although not proven, prolonged seizures may be more efficacious. The goal of this study was to evaluate and compare effects of alfentanil and remifentanil on seizure duration, recovery parameters and degree of stimulus amplitude in patients undergoing electroconvulsive therapy.

METHODS

Twenty-four ASA I-II patients enrolled in this prospective, randomized trial, each receiving a total of seven electroconvulsive therapies. Patients were randomized to receive only Propofol, group P (0.75 mg kg-1, n=8), Propofol with alfentanil, group A (10 microg kg-1 alfentanil+0.5 mg kg-1 Propofol, n=8) and Propofol with remifentanil, group R (1 microg kg-1 remifentanil +0.5 mg kg-1 propofol, n=8) via an iv route. Supplemental doses of propofol were given as required to achieve loss of consciousness. Succinylcholine 0.5 mg kg-1 iv was given to all groups for muscular paralysis. We recorded hemodynamic parameters, cortical and motor seizure durations, and recovery parameters.

RESULTS

Mean motor seizure duration was found to be significantly longer in patients receiving propofol-remifentanil anesthesia (53.3+/-13.6 s) and propofol-alfentanil anesthesia (52.2+/-0.4 s) compared with propofol anesthesia (37.6+/-9.2 s) (P=0.001). Recovery parameters and stimulus amplitudes were similar in groups A and R; significantly different from group P (P=0.001).

CONCLUSIONS

Adding 10 microg kg-1 alfentanil or 1 microg kg-1 remifentanil to reduced doses of propofol provided unconsciousness and increased seizure durations. For patients who need higher stimulus amplitudes for longer seizure durations, combining low-dose propofol with alfentanil or remifentanil may be good alternative regimens for ECT.

Propofol: an immunomodulating agent

Propofol (2,6-diisopropylphenol) is a potent intravenous hypnotic agent widely administered for induction and maintenance of anesthesia and for sedation in the intensive care unit. Propofol is insoluble in water and therefore is formulated in a lipid emulsion. In addition, a preservative (ethylenediaminetetraacetic acid [EDTA] or sodium metabisulfite) is added to retard bacterial growth. Propofol has antiinflammatory properties, decreasing production of proinflammatory cytokines, altering expression of nitric oxide, and inhibiting neutrophil function. Propofol also is a potent antioxidant. The added preservatives have biologic activity; EDTA has antiinflammatory properties, whereas metabisulfite may cause lipid peroxidation. The antiinflammatory and antioxidant properties of propofol may have beneficial effects in patients with sepsis and systemic inflammatory response syndrome.

Metabolic and endocrine effects of sedative agents

PURPOSE OF REVIEW

To bring to the attention of the clinician the metabolic effects of most common sedatives and analgesics used in critically ill patients.

RECENT FINDINGS

Most patients admitted to the intensive care unit require sedation and analgesia to reduce anxiety, agitation, and delirium and provide pain relief. Inappropriate sedation and analgesia techniques can cause harm to the already compromised patient if they do not take into account the metabolic effect they produce.

SUMMARY

Metabolically critical illness can be divided in two phases, and acute and a prolonged one. Whereas the acute or hypermetabolic phase is characterized by elevated circulating concentration of catabolic hormones and substrate utilization to provide energy to vital organs, the prolonged or catabolic phase of critical illness is marked by reduced endocrine stimulation and severe loss of body cell mass. The most common analgesic and sedative agents used in the intensive care unit, if used in small or moderate doses, do not interfere significantly with the metabolic milieu; however, prolonged infusions, and in high doses, without adequate monitoring of level of sedation and quality of analgesia, can precipitate morbid events. Further research is needed in the metabolic aspects of analgesia and sedation in the intensive care unit, particularly if a multimodal pharmacologic strategy is used whereby multiple interventions aim at minimizing the risk of overdosing and contributing to attenuation of the stress response associated with critical illness.

Sedation and safety of propofol for therapeutic endoscopic retrograde cholangiopancreatography

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) is the most complex gastrointestinal procedure, which needs patients' cooperation. The aim of this study was to observe the quality and safety of sedation with propofol in patients undergoing therapeutic ERCP.

METHODS

Seventy patients who had undergone therapeutic ERCP were randomly divided into two groups. One group,given intravenously propofol,and the other sedated with routine method,served as the control. Blood pressure,heart rate, oxygen saturation were monitored and cardiorespiratory event was observed. Patient cooperation, performance, recovery time and amnesia served as variables postoperation.

RESULTS

Blood pressure elevated in four patients in the propofol group, less than in the control group (P < 0.01). Seven patients showed decreased blood pressure after administration of propofol, but none in the control group (P < 0.01). Twelve patients in the control group showed mild or significant resistance, but none in the propofol group (P < 0.01). The time for performance in the propofol group (P < 0.05) was shorter than in the control group. Patient recovery was quicker in the propofol group than in the control group (P < 0.01). The degree of amnesia better in the propofol group than in the control group (P < 0.01). The degree of amnesia was also better in the propofol group than in the control group (P<0.01).

CONCLUSIONS

Propofol proves to be an excellent sedative for therapeutic ERCP. Being effective and safe, it shows a shorter ERCP duration but quick recovery and better amnesia. It is better than other routine sedatives.

Suxamethonium administration prolongs the duration of action of subsequent rocuronium

BACKGROUND AND AIM

Rocuronium may be given to patients for intubation and also after they have received suxamethonium for intubation. The neuromuscular profile of rocuronium given after recovery from suxamethonium may not be identical to that when rocuronium has been given alone. The neuromuscular effects of suxamethonium and rocuronium, and their effects on intraocular pressure (IOP), heart rate (HR) and arterial pressure were also recorded.

METHODS

Thirty patients were randomly allocated to receive either 0.6mg kg(-1) rocuronium (n = 15) or 1 mg kg(-1) suxamethonium (n = 15) for intubation. Anaesthesia was first induced using propofol 2.5 mg kg(-1) and fentanyl 2 microg kg(-1) and maintained with propofol 6-12 mg kg(-1) h(-1). The response of the thumb to supramaximal train-of-four (TOF) ulnar nerve stimulation at the wrist was measured using a mechanomyograph. In the suxamethonium group, when the first twitch of the TOF had recovered to 90%, rocuronium 0.6 mg kg(-1) was administered. Before administration of relaxant, baseline readings of HR, arterial pressure and IOP were measured until stable, then the appropriate relaxant administered. Thereafter, all readings were repeated at 30, 90, 150, 210 and 270 s. Tracheal intubation was performed 300 s after the intubating dose and all recordings repeated 30 s later. Mechanomyographic monitoring was continued until 70% TOF recovery.

RESULTS

Suxamethonium had a more rapid onset than rocuronium (49s vs. 74s, P < 0.0001). The onset time of rocuronium after suxamethonium was significantly reduced (56 s) and the time to recover to a TOF of 70% following rocuronium was increased by previous suxamethonium administration (47 vs. 58 min, P < 0.05). Suxamethonium caused a marked rise in IOP (>30%) and HR (>10%) while rocuronium had little effect on either.

CONCLUSION

Previous suxamethonium administration decreases the onset time and increases the duration of action of rocuronium. Unlike suxamethonium, rocuronium has few cardiovascular effects and causes little change in IOP.

The changing landscape of practice patterns regarding unsedated endoscopy and propofol use: a national Web survey

BACKGROUND

Lower reimbursements for endoscopic procedures and increasing demand for screening endoscopy over the past decade have spurred efforts to increase efficiency in the performance of endoscopic procedures. Two dichotomous approaches have emerged: (1) unsedated endoscopy and (2) propofol sedation. The aim was to determine national practice patterns of unsedated endoscopy and propofol sedation, and to assess endoscopists' attitudes toward unsedated screening with an electronic survey.

METHODS

A short survey was developed and then was converted to a Web-based format. All national members of the American Society for Gastrointestinal Endoscopy (ASGE) were invited via electronic mail (e-mail) to participate. Survey data were collected electronically.

RESULTS

Two e-mails elicited responses to the Web survey from 18% (724) of national ASGE members contacted, within 2 weeks. Of the respondents, 45% do not routinely offer unsedated EGD and colonoscopy, and only 15% of those respondents plan to incorporate unsedated endoscopy into their practice in the next year. Of the 55% who currently perform unsedated endoscopy, 85% do no more than 25 unsedated procedures per year. Lack of patient acceptance was the most common reason cited for not offering unsedated endoscopy. Most endoscopists felt that the availability of unsedated esophagoscopy or colonoscopy would not significantly increase screening for Barrett's esophagus or colonic polyps/colorectal cancer, respectively. Routine use of propofol sedation for EGD, colonoscopy, and ERCP/EUS was reported by 19%, 22%, and 19%, respectively. Community practitioners were more likely to use propofol than those at academic centers (p < 0.0002 for all). Of those not currently using propofol, 43% plan to incorporate it into their practice within the next year. Over 70% of respondents would themselves choose to be sedated for routine endoscopic procedures.

CONCLUSIONS

Electronic surveys allow for rapid distribution and data collection but suffer from a limited response rate. The survey suggests that unsedated endoscopy has limited acceptance in the United States, and, without a major intervention that affects endoscopists' attitudes, its use is not likely to increase significantly. Unsedated endoscopy will not have a great impact on endoscopic screening. In contrast, propofol sedation has already gained acceptance in the community, and the routine use of propofol in endoscopy units will likely increase in the future.

Antioxidant properties of propofol and erythropoietin after closed head injury in rats

Reactive oxygen species play a role during brain injury due to closed head trauma. Enzymatic or nonenzymatic antioxidants may protect brain tissue against oxidative damage. The present study was performed to assess the changes of endogenous indices of oxidative stress in serum from rats subjected to head trauma and whether treatment with propofol and/or erythropoietin (EPO) modifies the levels of endogenous indices of oxidative stress. For these purposes, female Wistar Albino rats were divided into five groups: non-traumatic sham group, trauma performed control, trauma with propofol (i.p.), trauma with EPO (i.p.) and trauma with propofol and EPO performed study groups. At the end of the experimental procedure, blood was taken by cardiac puncture to determine superoxide dismutase (SOD) and xanthine oxidase (XO) activities as well as malondialdehyde (MDA) and nitric oxide (NO) levels in serum. Serum MDA level of control traumatic brain injury (TBI) group was significantly higher than sham operation group (p<0.012). Serum MDA levels in propofol, EPO and propofol+EPO groups were found to be decreased in comparison with control group (p<0.039, p<0.030 and p<0.018, respectively). Serum NO level was found to be increased in TBI group, but difference was not statistically significant when compared to sham-operated group (p=0.092). Propofol, EPO and propofol+EPO administration efficiently reduced serum NO levels to reach sham-operated group (p<0.002, p<0.001 and p<0.015, respectively). These results suggested that acute administration of both propofol and EPO altered the indices of oxidative stress similarly against brain injury due to trauma.

Effects of post-treatment with low-dose propofol on inflammatory responses to lipopolysaccharide-induced shock in conscious rats

1. In the present study, we used a low dose of propofol (5 mg/kg per h) to investigate its effects on the pro-inflammatory cytokines (tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-10) and changes in nitric oxide (NO) following lipopolysaccharide (LPS) for a period of 12 h in conscious rats. 2. Experiments were designed to induce endotoxin shock by intravenous injection of Klebsiella pneumoniae LPS (10 mg/kg) in conscious rats. Arterial pressure (AP) and heart rate (HR) were monitored continuously for 12 h after LPS administration. Tumour necrosis factor-alpha, IL-1beta, IL-10 and plasma nitrates/nitrites were determined before and 0.5, 1, 3, 6, 9 and 12 h after LPS administration. A low dose of intravenous propofol (5 mg/kg per h) was administered to investigate the effects on cytokine responses and changes in NO in endotoxin shock. 3. Lipopolysaccharide significantly increased TNF-alpha, IL-1beta, IL-10, nitrites/nitrates and HR, whereas mean AP was decreased. Post-treatment with propofol suppressed the release of TNF-alpha, IL-1beta, IL-10 and NO production after endotoxin shock. 4. Lipopolysaccharide also caused a decrease in the white blood cell count and haematocrit. 5. Post-treatment with propofol slightly, but not significantly, affected the LPS-induced systemic hypotension, tachycardia, leukocytopenia and anaemia. 6. These findings suggest that low-dose propofol may be beneficial to the inflammatory change in sepsis.

Use of a remifentanil and propofol combination in outpatients to facilitate rapid discharge home

The goal of our study was to evaluate whether the combination of remifentanil and propofol facilitated shorter recovery time and decreased charges compared with conventional balanced anesthesia. We studied 49 patients, aged 13 to 75 years, who underwent elective outpatient surgery. All data were analyzed using the Pearson chi2 and the Student t test; results were considered statistically significant at a P value of.05 or less. Group 1 received a remifentanil-propofol combination and group 2, a conventional balanced anesthetic. Group 1 had decreased mean operating room (dollar 280.83 vs dollar 337.42; P = .05) and operating room plus postanesthesia care unit (PACU) (dollar 442.67 vs dollar 544.62) charges (P = .02). Group 1 had less PACU time (48.26 vs 59.62 minutes) and 2 group 1 patients bypassed the PACU. We conclude that a remifentanil-propofol combination is more cost effective than conventional balanced anesthetics and enables some patients to bypass the PACU, resulting in quicker discharge. Our findings have important implications for ambulatory surgery centers and office-based practices.

Sevoflurane as an alternative anaesthetic for electroconvulsive therapy

OBJECTIVES

The aim of this study was to investigate the effects of sevoflurane and propofol used in electroconvulsive therapy (ECT) on hemodynamic variables and duration of seizure activity and recovery profiles.

METHODS

Sixteen patients who were not premedicated, with a mean age 27.1 years, were enrolled in this prospective open trial, receiving a total of 64 ECT treatments. Each patient was given the following 2 anesthetic regimens in random order: In group S, anesthesia was induced with 7% sevoflurane in 100% oxygen at 6 L min fresh gas flow until the loss of consciousness and 1.5 mg kg propofol in group P. Adequate muscle relaxation was achieved with suxamethonium, 1.0 - 1.2 mg kg. Noninvasive mean arterial pressure (MAP) and heart rate (HR) values, duration of motor seizure activity, and recovery times were recorded.

RESULTS

The mean motor seizure duration was significantly longer with sevoflurane (mean [SD]: 43.09 [16.6] s) than with propofol (28.91 [7.9] s; P < 0.05). The MAP 1 minute and 10 minutes after ECT (101.25 [7.5] mm Hg and 100.16 [11.0] mm Hg, respectively) was significantly increased compared with before ECT (94.56 [6.9] mm Hg) in sevoflurane group (P < 0.05). Time to spontaneous breathing, eye opening and obeying commands, and changes in MAP and HR during and after ECT were similar in both regimens.

CONCLUSION

Induction with 7% sevoflurane allows prolonged duration of motor seizures in ECT. We concluded that induction of anesthesia with sevoflurane inhalation is a reasonable alternative for patients undergoing ECT.

Propofol infusion syndrome: an unusual cause of renal failure

Propofol infusion syndrome has been increasingly recognized as a syndrome of unexplained myocardial failure, metabolic acidosis, and rhabdomyolysis with renal failure. It has been described only with acute neurologic injury or acute inflammatory diseases complicated by severe infections or sepsis. It appears to develop in the context of high-dose, prolonged propofol (100 microg/kg/min) treatment in combination with catecholamines and/or steroids. This was first noted in children but is increasingly recognized in adults. This is a case report of 2 patients (a 42-year-old man and a 17-year-old girl) who had acute renal failure associated with use of propofol in the appropriate clinical setting. It examines the pathophysiology and the possible mechanisms of this condition and illustrates the need to consider it as the cause of rhabdomyolysis and acute renal failure in critically ill patients.

Dexmedetomidine does not improve patient satisfaction when compared with propofol during mechanical ventilation*

OBJECTIVE

Dexmedetomidine (DEX) may provide a sedation level that enables sleep and communication, with less amnesia and pain medication requirements, during mechanical ventilation. Our study directly assessed patient-perceived satisfaction with coronary artery bypass graft surgery after administration of DEX or propofol for intensive care unit (ICU) sedation.

DESIGN

Prospective, randomized clinical study with subsequent questionnaire administration.

SETTING

Tertiary care surgical ICU.

PATIENTS

A total of 89 adult, nonemergent, coronary artery bypass graft patients with an expected length of intubation of <24 hrs.

INTERVENTIONS

Patients were randomized to either DEX or propofol; drug administration was performed via standardized anesthesia and nursing protocols.

MEASUREMENTS

Patients reported perceptions of their ICU experience after mechanical ventilation with a modified numerical-scale Hewitt questionnaire, validated specifically for ICU patients. Patients were questioned regarding awareness, recall, generalized comfort, level of pain, ability to interact with healthcare providers and family, feelings of agitation and anxiety, perceived ease of extubation, ability to sleep or rest, and satisfaction with ICU experience.

MAIN RESULTS

Groups were well matched at baseline, with a mean +/- sd age of 63.0 +/- 10.4 yrs and weight of 88.7 +/- 16.7 kg. No difference was observed for length of surgery, length of intubation, or ICU stay (p > .05). DEX patients perceived a shorter length of intubation (p = .044). A deeper sedation level was found in the propofol group (p = .021), with similar morphine and midazolam requirements (p = .317). Patient-rated level of overall awareness as a marker of amnesia did not differ between groups (p = .653). The ability to rest or sleep trended toward significance favoring propofol (p = .051). On evaluation of questionnaire ratings, DEX patients expressed more discomfort (p = .046), pain (p = .096), and sleeping difficulty (p = .036). Similar comfort levels were reported during extubation (p = .179).

CONCLUSIONS

Despite theoretical advantages of DEX to improve overall patient satisfaction, the two agents provide similar responses to amnesia and pain control. According to our findings, DEX does not seem to have any advantage compared with propofol for short-term sedation after coronary artery bypass graft surgery.

Procedural Sedation and Analgesia: A Review and New Concepts

Procedural sedation and analgesia has become a commonplace procedure in the ED, certainly falling under the domain of the EP. Every EP should approach PSA as a complex procedure requiring high-level skills and knowledge. Initially, understand that PSA represents a spectrum of goals, from anxiolysis and pain relief to deep sedation. Assess the needs of the patient and the concomitant procedure and set goals accordingly. There is a pharmacopia of drugs that provide sedation and analgesia. Become familiar with their pharmacology, advantages and disadvantages, and indications. This will allow for appropriate usage and achievement of sedation goals. Several drugs that are commonly used for general anesthesia are proving themselves to be safe and efficacious for PSA. Both etomidate and propofol have emerged as useful drugs for PSA. Continued research and practice with these agents will add to our understanding and help define their use for PSA. Performing PSA as a procedure itself requires preparedness, diligent monitoring, and risk awareness. Knowing the patient's comorbid state and choosing agents that will not exacerbate their baseline status minimize risk. Following fasting guidelines is appropriate in certain clinical situations, and is prudent when time permits. However, these guidelines are a benchmark for minimizing risk and are not supported by evidence-based medicine. It is important to be cognizant of the guidelines but also to identify the emergency scenario where action must be taken despite the fasting guidelines. Controlling sedation depth also minimizes the risk of aspiration and other complications. The ETCO2 monitor and Bispectral Index may prove to be useful adjuncts for monitoring sedation depth. However, there is nothing yet that measures sedation depth quantitatively that can replace the qualitative assessment of the EP. More and more PSA is falling under the domain of the EP. It is important for the EP to be involved in hospital policy and guidelines associated with this procedure, and to remain aware of new research in this field. EPs can thereby contribute to quality assurance throughout the medical community by setting a standard in the practice of PSA, as they are not the only practitioners using this procedure. With continued practice and research, expertise in this field will grow measurably.

Propofol attenuates lung endothelial injury induced by ischemia-reperfusion and oxidative stress

Lung dysfunction after cardiopulmonary bypass and lung transplantation results from oxidant-mediated cellular damage. Previously, we observed the shedding of angiotensin-converting enzyme (ACE) from the endothelial cell surface to be a more sensitive and earlier marker of oxidative lung endothelial injury than lung wet-to-dry weight ratio. The aim of this study was to evaluate the potential of the anesthetic propofol, which has antioxidant properties, to prevent oxidative lung injury by measuring ACE shedding. ACE release from isolated perfused rat lungs increased significantly after ischemia-reperfusion (I/R). Propofol significantly decreased I/R-induced ACE release by 23.4% (P < 0.05). Perfusion with 0.75 mM H(2)O(2) also caused ACE release from the lung microvasculature, which was similarly attenuated by propofol. The protective effect of propofol on H(2)O(2)-induced ACE shedding was confirmed in vitro using Chinese Hamster Ovary cells overexpressing human ACE. Thus, propofol can attenuate oxidative injury of the pulmonary endothelium as detected by ACE shedding in I/R and H(2)O(2) models of acute lung injury.

Midlatency auditory-evoked potentials in the assessment of sedation in cardiac surgery patients

OBJECTIVES

Midlatency auditory-evoked potentials (MLAEPs) may provide an objective measure of depth of sedation. The aim of this study was to evaluate MLAEPs for measuring sedation in cardiac surgery patients.

DESIGN

Prospective study.

SETTING

Intensive care unit of a university hospital.

PARTICIPANTS

Twenty-two patients scheduled for elective coronary artery bypass grafting.

INTERVENTIONS

MLAEPs were obtained at 5 time points: the day before surgery (baseline), 1 hour before surgery, after premedication, postoperatively during deep (Ramsay 6) and moderate (Ramsay 4) sedation, and the day after surgery.

MEASUREMENTS AND MAIN RESULTS

The latency of the Nb MLAEP component increased from 44 ms (38-60 ms; median, range) at baseline to 49 ms (41-64 ms) after premedication (p = 0.03) and further to 63 ms (48-80 ms) during deep sedation after surgery (P < 0.01). Although a decreasing clinical level of sedation after rewarming was not associated with a significant change in Nb latency (61 ms [42-78 ms]), the MLAEP NaPa amplitude increased from 0.9 muV (0.4-1.6 microV) to 1.3 muV (0.8-3.9 microV; p = 0.01). Nb latency remained increased the day after surgery (49 ms [37-71 ms]) as compared with baseline (p < 0.01).

CONCLUSIONS

MLAEP latencies can reflect subtle changes in auditory perception, while amplitudes seem to change with transition between deep levels of sedation.

Intrathecal propofol has analgesic effects on inflammation-induced pain in rats

PURPOSE

Propofol is thought to act on gamma-aminobutyric acid receptors, which have some role in pain transmission in the spinal cord. In this study, we examined the effects of intrathecal propofol on acute thermally- or inflammation-induced pain in rats.

METHODS

Lumbar intrathecal catheters were implanted in Male Sprague-Dawley rats. The tail withdrawal response to thermal stimulation (tail flick test) or paw flinching and shaking response by sc formalin injection into the hind paw (formalin test) were tested. Propofol 1000, 300 or 100 microg or saline (control) was administered as 10 microL intrathecally. Motor disturbance and behavioural side effects were also monitored in the rats during the tail flick test. Eight rats were used for each dose in each test.

RESULTS

No analgesic effects were observed in the tail flick test. In the formalin test, 50% of effective doses were 449 mug (95% confidence interval, 80-3180 microg) in phase 1 and 275 microg (146-519 microg) in phase 2. Motor disturbance was observed in one rat with 100 microg and agitation and allodynia were seen in one rat with 300 microg. However, both were reversible in 120 min.

CONCLUSIONS

Intrathecal administration of propofol had analgesic effects on inflammation-induced acute and facilitated pain but not on thermally-induced acute pain. Transient motor and sensory disturbance could not rule out the possibility of neurotoxicity.