Propofol in patients with cardiac disease

Comparative Electroencephalographic Profile of a New Anesthetic and Anticonvulsant That Is Selective for the GABAAR Slow Receptor Subtype

BACKGROUND

Anesthetics like propofol increase electroencephalography (EEG) power in delta frequencies (0.1-4 Hz), with a decrease of power in bandwidths >30 Hz. Propofol is nonselective for gamma amino butyric acid type A receptor subtypes (GABAAR) as it enhances all 3 GABAAR subtypes (slow, fast, and tonic). Our newly developed anesthetic class selectively targets GABAAR-slow synapses to depress brain responsiveness. We hypothesized that a selective GABAAR-slow agonist, KSEB 01-S2, would produce a different EEG signature compared to the broad-spectrum GABAAR agonist (propofol), and tested this using rat EEG recordings.

METHODS

Male rats were studied after Institutional Animal Care and Use Committees (IACUC) approval from the US Army Medical Research Institute of Chemical Defense and the University of Michigan. Rats were anesthetized using isoflurane (3%-5% induction, 1%-3% maintenance) with oxygen at 0.5 to 1.0 L/min. Stainless steel screws were placed in the skull and used to record subcranial cortical EEG signals. After recovery, either propofol or KSEB 01-S2 was administered and effects on EEG signals were analyzed.

RESULTS

As previously reported, propofol produced increased power in delta frequencies (0.1-4 Hz) compared to predrug recordings and produced a decrease in EEG power >30 Hz but no significant changes were seen within ±20 seconds of losing the righting reflex. By contrast, KSEB 01-S2 produced a significant increase in theta frequency percent power (median 14.7%, 16.2/13.8, 75/25 confidence interval; to 34.7%, 35/31.8; P < .015) and a significant decrease in low gamma frequency percent power (16.9%, 18.6/15.8; to 5.45%, 5.5/5.39; P < .015) for all rats at ± 20 seconds of loss of consciousness (LOC). Both anesthetics produced a flattening of chaotic attractor plots from nonlinear dynamic analyses, like that produced by volatile and dissociative anesthetics at LOC.

CONCLUSIONS

KSEB 01-S2 produced a markedly different EEG pattern, with a selective increase observed in the theta frequency range. KSEB 01-S2 also differs markedly in its activity at the GABAAR-slow receptor subtype, suggesting a possible mechanistic link between receptor subtype specificity and EEG frequency band signatures. Increased theta together with depressed gamma frequencies is interesting because GABAAR slow synapses have previously been suggested to underlie theta frequency oscillations, while fast synapses control gamma activity. These reciprocal effects support a previous model for theta and nested gamma oscillations based on inhibitory connections between GABAAR fast and slow interneurons. Although each anesthetic produced a unique EEG response, propofol and KSEB 01-S2 both increased slow wave activity and flattened chaotic attractor plots at the point of LOC.

Propofol pretreatment inhibits ferroptosis and alleviates myocardial ischemia-reperfusion injury through the SLC16A13-AMPK-GPX4 pathway

This study investigates the protective effects of propofol on the myocardium by inhibiting the expression of SLC16A13 through in vivo animal experiments, while also exploring its mechanism in ferroptosis to provide new strategies for preventing perioperative myocardial ischemia-reperfusion injury. We randomly divided 30 rats into three groups (n=10 each): sham surgery group, ischemia-reperfusion (I/R) group, and propofol pretreatment group. The results showed that compared with the sham surgery group, the I/R group had a significant decrease in cardiac function and an increase in infarct size. Propofol pretreatment effectively alleviated the damage caused by ischemia-reperfusion (I/R). In the next phase of the study, we administered the PPARα agonist GW7647 to artificially increase the expression of SLC16A13. Fifty rats were randomly divided into five groups (n=10 each), with the GW7647 pretreatment group and propofol+GW7647 pretreatment group added based on the previous three groups. Afterwards, we validated the in vivo results using H9C2 and further explored the mechanism by which propofol inhibits ferroptosis. The study found that L-lactic acid in myocardial tissue of the GW7647 group was further increased compared to the I/R group, and the degree of ferroptosis was aggravated. In addition, upregulation of SLC16A13 significantly inhibited the phosphorylation of AMPK, weakened the protective mechanism of AMPK, and exacerbated cardiac damage. However, propofol pretreatment can effectively inhibit the expression of SLC16A13, maintain normal myocardial cell morphology, and protect cardiac function. These results indicate that propofol inhibits the expression of SLC16A13, alleviates myocardial cell ferroptosis via the AMPK/GPX4 pathway, and reverses damage caused by myocardial ischemia-reperfusion.

Low-Dose Propofol with Peribulbar Anaesthesia for Cataract Surgery

In this paper, we investigate the effect of sedation using low-dose propofol on patient reported outcome measures (PROMS) in patients undergoing cataract surgery. This is a randomised, single-blinded observational prospective study. Patients undergoing elective cataract surgery using peribulbar anaesthesia over consecutive cataract lists were selected for this trial. Patients were randomised to receive either no sedation or low-dose propofol (20 to 30 mg followed by 10 mg increments until the patient developed slurred speech alone) prior to the administration of local anaesthesia. Pain, satisfaction, anxiety, needle recall, pulse, and blood pressure (BP) were measured. A total of 97 patients were included, 50 of whom received propofol. There were 4 senior surgeons and anaesthetists. There were no ocular or systemic complications and all patients had uncomplicated surgery. Anxiety (p = 0.026), needle recall (p < 0.001), difference in systolic BP (p = 0.043), and pulse (p = 0.046) were dependent on patient age (p < 0.001) and the use of propofol (p = 0.007). Lower pain was associated with propofol (p = 0.008), as well as lower anxiety (p = 0.002), and increased patient age (p = 0.014). The administration of propofol was significantly associated with lower needle recall (p < 0.001), pre- to post-operative difference in systolic BP (p = 0.029), and mean BP (p = 0.044). Low-dose propofol given immediately prior to administration of local anaesthesia was associated with reduced pain and needle recall, as well as lower BP.

A case of refractory ventricular fibrillation after caffeine poisoning successfully treated by supportive care

Caffeine (1,3,7-trimethylxantine), a structural analog of adenosine, is widely used as a central nervous system stimulant in beverages and drugs. Caffeine overdose induces hypokalemia, fatal ventricular fibrillation, and cardiac arrest, resulting in death. We describe a case of caffeine overdose that presented with refractory ventricular fibrillation that was treated with supportive care because invasive care for severely ill patients was limited due to the COVID-19 pandemic. A 20-year-old woman with no underlying medical history ingested 90,200-mg caffeine tablets (total dose 18 g) in a suicide attempt. She was transported to the emergency department 45 min after ingestion with dizziness, palpitations, nausea, and vomiting. She developed cardiac arrest 80 min after ingesting the caffeine, with refractory ventricular tachycardia that recurred for about 2.5 h. Advanced life support including defibrillation was started immediately and we gave intravenous Intralipid emulsion, potassium chloride, amiodarone, and esmolol, without hemodialysis or extracorporeal membrane oxygenation (ECMO). The ventricular fibrillation was stopped 4 h after ingestion. As supportive care, mechanical ventilation, sedatives, and neuromuscular blockade were continued until 12 h after ingestion. Although she suffered from prolonged, refractory ventricular tachycardia, she recovered without complications. This case report describes the clinical course of severe caffeine intoxication without an active elimination method, such as hemodialysis or ECMO and explores the treatment of caffeine intoxication with a literature review.

Propofol inhibits oxidative stress injury through the glycogen synthase kinase 3 beta/nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway

Oxidative stress is the main cause of ischemia/reperfusion injury. Propofol is a commonly used intravenous hypnotic anesthetic agent with antioxidant properties. In this study, we aimed to elucidate the protective effects of propofol on H2O2-induced cardiomyocyte injury and myocardial ischemic/reperfusion injury (MIRI) in rats. Cardiomyocyte injury was evaluated by determining cardiac troponin-1 (cTn-1) and creatine kinase-MB (CK-MB) levels. Antioxidative stress was assessed by measuring lactate dehydrogenase (LDH), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), reactive oxygen species (ROS), and catalase (CAT) levels. Apoptosis was evaluated using flow cytometry and TUNEL assays. Bax and Bcl-2 expression levels were determined by quantitative reverse transcription PCR (qRT-PCR) and Western blotting. The levels of glycogen synthase kinase 3 beta/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway-related factors were measured using Western blotting. Myocardial infarction in rats was analyzed using an Evans blue staining assay. The results showed that propofol reduced the levels of CK-MB, cTn-1, LDH, MDA, and ROS, and increased the levels of GSH, SOD, and CAT in H2O2-treated H9c2 cells. Additionally, propofol inhibited H2O2-induced apoptosis by downregulating Bax and upregulating Bcl-2. Moreover, propofol decreased the area of myocardial infarction in rats with MIRI. The GSK3β-Nrf2/HO-1 signaling pathway was activated by propofol. Rescue experiments showed that Nrf2 knockdown alleviated the effects of propofol on oxidative stress and apoptosis in H9c2 cells. In conclusion, propofol attenuated H2O2-induced myocardial cell injury by regulating the GSK3β/Nrf2/HO-1 signaling pathway and alleviating MIRI, suggesting that propofol is a promising therapeutic option for ischemic heart disease.

Functional Modular Network Identifies the Key Genes of Preoperative Inhalation Anesthesia and Intravenous Anesthesia in Off-Pump Coronary Artery Bypass Grafting

Off-pump coronary artery bypass grafting (OPCABG) is an effective strategy for revascularization. Preoperative anesthesia appears critical due to surgical instability and the risk of organ damage. This study, based on a functional module network, analysed the effects of preoperative inhalation anesthesia and intravenous anesthesia on OPCABG and performed a pivot analysis of its potential drug regulators. We obtained microarray data of sevoflurane anesthesia and propofol anesthesia from the GEO database and analysed the difference between the two groups of data, resulting in 5701 and 3210 differential genes to construct the expression matrix. WGCNA analysis showed that sevoflurane anesthesia clustered into 7 functional disorder modules, including PDCD6IP, WDR3, and other core genes; propofol anesthesia clustered to form two functional disorder modules, including KCNB2 and LHX2, two core genes Enrichment analysis of the functions and pathways of interest suggests that both anesthesia-related module genes tend to function as pathways associated with ion and transmembrane transport. The underlying mechanism may be that targeted regulation of transmembrane-associated biological processes and ion pathways in the core genes of each module affect the surgical process. Pivot analysis of potential drug regulators revealed 229 potential drugs for sevoflurane anesthesia surgery, among which zinc regulates three functional disorder modules via AHSG, F12, etc., and 67 potential drugs for propofol anesthesia surgery, among which are propofol, methadone, and buprenorphine, regulate two functional disorder modules through four genes, CYP2C8, OPRM1, CYP2C18, and CYP2C19. This study provides guidance on clinical use or treatment by comparing the effects of two anesthesias on surgery and its potential drugs.

Propofol suppresses ventricular arrhythmias: a case report of acute caffeine intoxication

Background

Caffeine is widely used as a stimulant drug throughout the world, and fatal arrhythmia is a known side‐effect. We experienced a patient with caffeine intoxication causing fatal arrhythmias who was successfully treated with the infusion of propofol.

Case Presentation

A 27‐year‐old woman was transferred to our hospital with nausea and poor general condition after intentional ingestion of 23.2 g of caffeine tablets. She was in cardiac arrest due to ventricular fibrillation just before hospital arrival. Advanced life support including defibrillation was started immediately, and we succeeded in resuscitating her 23 min later. Although she suffered from polymorphic ventricular premature beats and frequent transition to ventricular fibrillation, propofol administration converted her from a ventricular arrhythmia to sinus rhythm.

Conclusion

We report this case focusing on the cardiovascular effects of propofol and the lipid sink phenomenon. As a result, propofol could have the potential to suppress ventricular arrhythmias.

Interventional radiology in the airway in children

Interventional procedures in the airway can be performed in interventional radiology suites or the operating room, by radiologists or other specialists. The most common therapeutic interventions carried out by radiologists are balloon dilatation, stenting, and the treatment of certain airway fistulas. These operations can be very challenging for anesthetists in terms of planning, airway management, the identification and treatment of procedural complications and postoperative care. In particular, a multidisciplinary approach to decision-making and planning is important to obtain the best results.

Positive Pressure Ventilation in Cardiogenic Shock: Review of the Evidence and Practical Advice for Patients With Mechanical Circulatory Support

Cardiogenic shock (CS) is often complicated by respiratory failure, and more than 80% of patients with CS require respiratory support. Elevated filling pressures from left-ventricular (LV) dysfunction lead to alveolar pulmonary edema, which impairs both oxygenation and ventilation. The implementation of positive pressure ventilation (PPV) improves gas exchange and can improve cardiovascular hemodynamics by reducing preload and afterload of the LV, reducing mitral regurgitation and decreasing myocardial oxygen demand, all of which can help augment cardiac output and improve tissue perfusion. In right ventricular (RV) failure, however, PPV can potentially decrease preload and increase afterload, which can potentially lead to hemodynamic deterioration. Thus, a working understanding of cardiopulmonary interactions during PPV in LV and RV dominant CS states is required to safely treat this complex and high-acuity group of patients with respiratory failure. Herein, we provide a review of the published literature with a comprehensive discussion of the available evidence on the use of PPV in CS. Furthermore, we provide a practical framework for the selection of ventilator settings in patients with and without mechanical circulatory support, induction, and sedation methods, and an algorithm for liberation from PPV in patients with CS.

Advancing emergency airway management practice and research

Emergency airway management is one of the vital resuscitative procedures undertaken in the emergency department (ED). Despite its clinical and research importance in the care of critically ill and injured patients, earlier studies have documented suboptimal intubation performance and high adverse event rates with a wide variation across the EDs. The optimal emergency airway management strategies remain to be established and their dissemination to the entire nation is a challenging task. This article reviews the current published works on emergency airway management with a focus on the use of airway management algorithms as well as the importance of first‐pass success and systematic use of rescue intubation strategies. Additionally, the review summarizes the current evidence for each of the important airway management processes, such as assessment of the difficult airway, preparation (e.g., positioning and oxygenation), intubation methods (e.g., rapid sequence intubation), medications (e.g., premedications, sedatives, and neuromuscular blockades), devices (e.g., direct and video laryngoscopy and supraglottic devises), and rescue intubation strategies (e.g., airway adjuncts and rescue intubators), as well as the airway management in distinct patient populations (i.e., trauma, cardiac arrest, and pediatric patients). Well‐designed, rigorously conducted, multicenter studies that prospectively and comprehensively characterize emergency airway management should provide clinicians with important opportunities for improving the quality and safety of airway management practice. Such data will not only advance research into the determination of optimal airway management strategies but also facilitate the development of clinical guidelines, which will, in turn, improve the outcomes of critically ill and injured patients in the ED.

The Impact and Mechanism of a Novel Allosteric AMPA Receptor Modulator LCX001 on Protection Against Respiratory Depression in Rodents

Analgesics and sedative hypnotics in clinical use often give rise to significant side effects, particularly respiratory depression. For emergency use, specific antagonists are currently administered to counteract respiratory depression. However, antagonists are often short-lasting and eliminate drug generated analgesia. To resolve this issue, novel positive AMPA modulators, LCX001, was tested to alleviate respiratory depression triggered by different drugs. The acetic acid writhing and hot-plate test were conducted to evaluate analgesic effect of LCX001. Binding assay, whole-cell recording, live cell imaging, and Ca²⁺ imaging were used to clarify mechanism and impact of LCX001 on respiratory protection. Results showed that LCX001 effectively rescued and prevented opioid (fentanyl and TH-030418), propofol, and pentobarbital-induced respiratory depression by strengthening respiratory frequency and minute ventilation. The acetic acid writhing test and hot-plate test revealed potent anti-nociceptive efficacy of LCX001, in contrast to other typical ampakines that did not affect analgesia. Furthermore, LCX001 potentiated [³H]AMPA and L-glutamate binding affinity to AMPA receptors, and facilitated glutamate-evoked inward currents in HEK293 cells stably expressing GluA2(R). LCX001 had a typical positive modulatory impact on AMPAR-mediated function. Importantly, application of LCX001 generated a significant increase in GluA2(R) surface expression, and restrained opioid-induced abnormal intracellular Ca²⁺ load, which might participate in breathing modulation. Our study improves therapeutic interventions for the treatment of drug induced respiratory depression, and increases understanding of potential mechanism of AMPA receptor modulators.

Editor’s Choice- Sedation in the coronary intensive care unit: An adapted algorithm for critically ill cardiovascular patient

In the current era, cardiovascular intensive care units care for more complex patients who are far sicker than historical post-myocardial infarction patients, and sedation has become a common intervention in these units. Current sedation best practices derive mainly from non-cardiac units which limits their generalization to the critically ill cardiac patient. Thus, a great variability in sedation protocols, especially the selection of sedative agents, is commonly seen in daily practice across cardiac units. We present an updated review on sedation in cardiovascular critical care medicine with emphasis on the hemodynamic impact. The goal of this review is to generate a general sedation algorithm specific for the cardiac patient.

Sedation and Analgesia

Patients in the cardiothoracic intensive care unit (CTICU) are subject to numerous physical and mental stresses. While most of these cannot be completely eliminated, intensivists have many tools in their armamentarium to alleviate patients' pain and suffering. This chapter will consider the importance of analgesia and sedation in the CTICU and the relevant consequences of over- or under-treatment. We will examine the tools available for monitoring and titrating analgesia and sedation in critically ill patients. The major classes of medications available will be reviewed, with particular attention to their clinical effects, metabolism and excretion, and hemodynamic characteristics. Lastly, experimental evidence will be assessed regarding the best strategies for treatment of pain and agitation in the CTICU, including use of non-pharmacologic adjuvants.

Comparison between Midazolam Used Alone and in Combination with Propofol for Sedation during Endoscopic Retrograde Cholangiopancreatography

Background/Aims

Endoscopic retrograde cholangiopancreatography (ERCP) is an uncomfortable procedure that requires adequate sedation for its successful conduction. We investigated the efficacy and safety of the combined use of intravenous midazolam and propofol for sedation during ERCP.

Methods

A retrospective review of patient records from a single tertiary care hospital was performed. Ninety-four patients undergoing ERCP received one of the two medication regimens, which was administered by a nurse under the supervision of a gastroenterologist. Patients in the midazolam (M) group (n=44) received only intravenous midazolam, which was titrated to achieve deep sedation. Patients in the midazolam pulse propofol (MP) group (n=50) initially received an intravenous combination of midazolam and propofol, and then propofol was titrated to achieve deep sedation.

Results

The time to the initial sedation was shorter in the MP group than in the M group (1.13 minutes vs. 1.84 minutes, respectively; p<0.001). The recovery time was faster in the MP group than in the M group (p=0.031). There were no significant differences between the two groups with respect to frequency of adverse events, pain experienced by the patient, patient discomfort, degree of amnesia, and gag reflex. Patient cooperation, rated by the endoscopist as excellent, was greater in the MP group than in the M group (p=0.046).

Conclusions

The combined use of intravenous midazolam and propofol for sedation during ERCP is more effective than midazolam alone. There is no difference in the safety of the procedure.

Perioperative management for the removal of a massive ovarian cystadenoma

We describe the perioperative management of a patient requiring removal of a 56.7-kg ovarian cystadenoma, highlighting our techniques in managing the changes in the patient's respiratory, vascular, renal, and gastrointestinal systems due to the large mass. An appreciation of the unique physiologic and anatomical changes in patients with large abdominal masses allows for appropriate precautions in the perioperative period.

Coadministration of the AMPAKINE CX717 with propofol reduces respiratory depression and fatal apneas

BACKGROUND

Propofol (2,6-diisopropylphenol) is used for the induction and maintenance of anesthesia in human and veterinary medicine. Propofol's disadvantages include the induction of respiratory depression and apnea. Here, the authors report a clinically feasible pharmacological solution for reducing propofol-induced respiratory depression via a mechanism that does not interfere with anesthesia. Specifically, they test the hypothesis that the AMPAKINE CX717, which has been proven metabolically stable and safe for human use, can prevent and rescue from propofol-induced severe apnea.

METHODS

The actions of propofol and the AMPAKINE CX717 were measured via (1) ventral root recordings from newborn rat brainstem-spinal cord preparations, (2) phrenic nerve recordings from an adult mouse in situ working heart-brainstem preparation, and (3) plethysmographic recordings from unrestrained newborn and adult rats.

RESULTS

In vitro, respiratory depression caused by propofol (2 μM, n = 11, mean ± SEM, 41 ± 5% of control frequency, 63 ± 5% of control duration) was alleviated by CX717 (n = 4, 50-150 μM). In situ, a decrease in respiratory frequency (44 ± 9% of control), phrenic burst duration (66 ± 7% of control), and amplitude (78 ± 5% of control) caused by propofol (2 μM, n = 5) was alleviated by coadministration of CX717 (50 μM, n = 5). In vivo, pre- or coadministration of CX717 (20-25mg/kg) with propofol markedly reduced propofol-induced respiratory depression (n = 7; 20mg/kg) and propofol-induced lethal apnea (n = 6; 30 mg/kg).

CONCLUSIONS

Administration of CX717 before or in conjunction with propofol provides an increased safety margin against profound apnea and death.

Balanced propofol sedation versus propofol monosedation in therapeutic pancreaticobiliary endoscopic procedures

BACKGROUND

Prolonged or complex endoscopic procedures are frequently performed under deep sedation. However, no studies of therapeutic ERCP have yet compared the use of balanced propofol sedation (BPS) to propofol alone, titrated to moderate levels of sedation.

AIM

This prospective, randomized, double-blind study was planned to compare the sedation efficacy and safety of BPS (propofol in combination with midazolam and fentanyl) and propofol monosedation in therapeutic ERCP and EUS.

METHODS

BPS, or propofol monosedation titrated to a moderate level of sedation, was performed by trained registered nurses under endoscopist supervision. The main outcome measurements included sedation efficacy focusing on recovery time, sedation safety, endoscopic procedure outcomes, and complications.

RESULTS

There were no significant differences in sedation efficacy, safety, procedure outcomes, and complications, with the exception of recovery time. Mean recovery time (standard deviation) was 18.37 (7.86) min in BPS and 13.4 (6.24) min in propofol monosedation (P < 0.001). In a safety analysis, cardiopulmonary complication rates related to BPS and propofol monosedation were 7.8 % (8/102) and 9.6 % (10/104), respectively (P = 0.652). No patient required assisted ventilation or permanent termination of a procedure in either group. Technical success of the endoscopic procedures was 96.3 and 97.2 %, respectively (P = 0.701). Endoscopic procedure-related complications and outcomes did not differ depending on sedation procedure.

CONCLUSIONS

Propofol monosedation by trained, registered sedation nurses under supervision resulted in a more rapid recovery time than BPS. There were no differences in the sedation safety, endoscopic procedure outcomes, and complications between BPS and propofol monosedation.

Alternative use of isoflurane and propofol confers superior cardioprotection than using one of them alone in a dog model of cardiopulmonary bypass

Our previous clinical study reported that isoflurane preconditioning and high-dose propofol posttreatment attenuated myocardial ischemia/reperfusion injury of patients in surgery with cardiopulmonary bypass (CPB). This study was designed to confirm this cardiac protection by use of a dog CPB model and to elucidate the related mechanism. Adult mongrel male dogs undergoing standard CPB were assigned into 4 groups: Sham group, Propofol group, Isoflurane (Iso) group and isoflurane in combination of propofol (pre-Iso+P) group. After induction, anesthesia was maintained with propofol (Propofol group), isoflurane (Iso group) or isoflurane preconditioning in combination with propofol posttreatment (pre-Iso+P group). After 2 h cardiac arrest and CPB, aortic cross-clamping was released to allow 2 h reperfusion. The results demonstrated that joint use of isoflurane and propofol facilitated cardiac functional recovery, improved myocardial oxygen utilization and decreased cardiac enzyme release. Also, the oxidative damage caused by ischemia/reperfusion injury was remarkably attenuated. Linear regression analysis showed that cardiac function performance and oxidative stress status were inversely correlated, indicating the improved cardiac function was in closed association with the attenuation of oxidative stress. In addition, the cardiac oxygen consumption (VO(2)) was found to be significantly associated with the above cardiac function and oxidative stress parameters, suggesting VO(2) was predictive for the levels of cardiac damage and oxidative stress. Therefore, we conclude that alternative use of isoflurane and propofol confers superior cardioprotection against postischemic myocardial injury and dysfunction, and this protection was probably mediated by attenuation of cardiac oxidative damage.

Sedation with dexmedetomidine hydrochloride during endoscopic submucosal dissection of gastric cancer

AIM

Although the treatment of early gastric cancer with endoscopic submucosal dissection (ESD) has been widely carried out, a standardized method of sedation for ESD has not been established. The purpose of the present study was to evaluate the efficacy and safety of sedation with dexmedetomidine (DEX).

METHODS

We conducted a randomized study involving 90 patients with gastric tumors who were intended to be treated with ESD. The patients were sedated either with DEX (i.v. infusion of 3.0 µg/kg per h over 5 min followed by continuous infusion at 0.4 µg/kg per h [n = 30]), propofol (PF [n = 30]), or midazolam (MDZ [n = 30]). In all groups, 1 mg MDZ was added i.v. as needed.

RESULTS

En bloc resection of the gastric tumor was achieved in 88 (98%) patients. None of the DEX-sedated patients showed a significant reduction of the oxygen saturation level. The percentage of patients who showed body movement in the DEX group was significantly lower than those in the PF and MDZ groups, and the mean dose of additional MDZ in the DEX group was significantly smaller than that in the MDZ group. The rate of effective sedation was significantly higher in the DEX group compared with the MDZ or PF group. The mean length of ESD in the DEX group was 65 min, which was significantly shorter than in the other two groups. No DEX-sedated patient developed major surgical complications.

CONCLUSIONS

Sedation with DEX is effective and safe for patients with gastric tumors who are undergoing ESD.

Effects of Propofol and Midazolam on Lipids, Glucose, and Plasma Osmolality during and in the Early Postoperative Period Following Coronary Artery Bypass Graft Surgery: A Randomized Trial

It is not clear how levels of serum lipids and glucose and plasma osmolality change during propofol infusion in the pre- and postoperative period of coronary artery bypass graft surgery (CABG). This prospective, randomized, controlled trial evaluated changes in these parameters during propofol or midazolam infusion during and in the early postoperative period following surgery. Twenty patients undergoing CABG were randomized preoperatively into two groups: 10 patients received propofol (induction 1.5 mg/kg, maintenance 1.5 mg kg(-1) h(-1)) and 10 patients received midazolam (induction 0.5 mg/kg, maintenance 0.1 mg kg(-1) h(-1)). Both groups also received fentanyl (induction 20 mug/kg, maintenance 10 microg kg(-1)). Serum lipids, glucose, and plasma osmolality were measured preinduction, precardiopulmonary bypass, at the end of cardiopulmonary bypass, at the end of surgery, and 4 and 24 h postoperatively. In the propofol group, we observed a significant increase in triglycerides and very low-density lipoprotein levels 4 h postoperatively. In the midazolam group, we observed a significant decrease in low-density lipoprotein, cholesterol at the end of cardiopulmonary bypass, end of surgery, and 4 and 24 h postoperatively and significant increase in osmolality at the end of cardiovascular bypass. Changes in glucose levels did not differ significantly different between the two groups. In patients with normal serum lipids, glucose, and plasma osmolality undergoing CABG, propofol infusion for maintenance anesthesia is not associated with dangerous changes in serum lipids, glucose, and plasma osmolality compared with midazolam. A propofol infusion technique for maintenance of anesthesia for cardiac surgery where serum lipids and glucose may be of concern could be recommended as an alternative to midazolam.

Synergistic sedation with oral midazolam as a premedication and intravenous propofol versus intravenous propofol alone in upper gastrointestinal endoscopies in children: a prospective, randomized study

OBJECTIVES

The primary objective of the present study was to compare the required dose of intravenous (IV) propofol between group A (synergistic sedation with an oral dose of midazolam combined with IV propofol) and group B (IV propofol alone), in diagnostic upper gastrointestinal endoscopy (UGIE) in pediatric patients. The secondary objective was to compare the safety, the efficacy, the ease of IV line placement and the ease of separation from parents between the 2 groups.

METHODS

Fifty-four consecutive children (aged 3 y or older) who underwent UGIE were randomly assigned to 1 of the 2 medication regimens. Patients in group A (n = 26, mean age: 8.1 y) received midazolam (0.5 mg/kg) orally. Thirty minutes after the midazolam dose was given, repeated IV doses of propofol 0.5 mg/kg were administered titrated to achieve the level of deep sedation. Patients in group B (n = 28, mean age: 9 y) received IV propofol alone with the same methodology and sedation end point.

RESULTS

The mean dose (1.8 +/- 0.7 mg/kg) of propofol administered in group A patients was remarkably lower compared with that (2.9 +/- 0.9 mg/kg) of group B. Multivariate stepwise logistic regression analysis revealed that among sex, age, ASA grade and the type of sedation, the synergistic sedation was the only factor associated with the ease of IV line placement (chi(2) = 16.3, P < 0.001) and the ease of separation from parents (chi(2) = 41.6, P < 0.001). Additional multivariate stepwise logistic regression analysis revealed that among sex, age, ASA grade and the type of sedation, synergistic sedation was the only factor associated with a higher level of patient comfort (chi(2) = 35.5, P < 0.001). The recovery time was significantly shorter in group B patients (7.7 +/- 3.6 min) compared with that of group A (25.9 +/- 4.1 minutes) (P < 0.01). The 2 regimens were equally safe.

CONCLUSIONS

Our data suggest that synergistic sedation with an oral dose of midazolam combined with propofol may benefit the children who undergo UGIE with regard to lower mean dose of propofol used, easier IV line placement, easier separation from the parents, less pain induced by the IV line placement and greater patient comfort.

Moderate Intravenous Sedation for Office-Based Full Face Laser Resurfacing Using a Continuous Infusion Propofol Pump

PURPOSE

The purpose of this study was to compare the anesthetic requirements and hemodynamic and oxygenation variables involved between the bolus midazolam/fentanyl intravenous sedation-analgesia technique, and the same technique combined with continuous-infusion propofol.

PATIENTS AND METHODS

This was a retrospective chart analysis of 41 consecutive patients undergoing full-face carbon dioxide laser resurfacing with either bolus midazolam/fentanyl (n = 15) or midazolam/fentanyl with continuous propofol infusion anesthesia (n = 26) techniques. Data recorded were noninvasive baseline and intraoperative hemodynamic measurements at 5-minute intervals for systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse pressure (PP), pulse (P), and rate-pressure product (RPP), respiratory rate (RR), and oxygen saturation (SpO2). Data collected were reported as mean values with standard deviation. Statistical analyses were performed with the Student's t test and found statistically significant for P < .05.

RESULTS

Statistically significant decreases in averages were seen in SBP (P < .001), DBP (P = .02), MAP (P = .004), P (P < .00l), RPP (P < .00l), and RR (P < .001), but not PP (P = .4) and SpO2 (P = .08) in the midazolam/fentanyl/continuous propofol infusion group compared with the midazolam/fentanyl only group. Changes from baseline were statistically significant only for MAP (P = .04), but statistically insignificant for all other measurements, SBP (P = .7), DBP (P = .4), P (P = .95), PP (P = .97), RPP (P = .6), RR (P = .6), and SpO2 (P = .4). Statistically significant smaller amounts of midazolam (P = .01) and fentanyl (P < .001) were used in the midazolam/fentanyl/continuous propofol infusion pump group. Length of procedure was statistically insignificant between groups (P = .4). Conclusion The addition of a continuous propofol pump maintained hemodynamic and oxygenation values close to baseline, while decreasing the amount of respiratory depressing opiates administered and without affecting the length of the procedure.

Perioperative hemodynamic measurements with an implantable monitoring system (Chronicle) in a patient with severe heart failure undergoing non-cardiac surgery

A 53-year-old male patient with severe chronic heart failure due to ischemic cardiomyopathy (LVEF 25%) awaiting heart transplantation was admitted for resection of a bladder tumor. The patient underwent implantation of a Chronicle implantable hemodynamic monitor (IHM) two years before. Thus, perioperative monitoring of heart rate, right ventricular systolic, diastolic and pulse pressure, dP/dt and estimated pulmonary artery diastolic pressure through a lead implanted in the right ventricle was performed. In the postoperative period the patient developed low-output syndrome requiring catecholamine treatment. The patient was weaned from mechanical ventilation uneventfully the same day. However, he developed symptomatic and hemodynamic worsening of heart failure shortly after reduction of inotropes and required prolonged medical treatment with catecholamines. Patients with cardiac disease are known to be at increased risk for cardiovascular complications after noncardiac surgery. Therefore, it has been suggested that such patients could potentially benefit from perioperative invasive hemodynamic monitoring. For the first time, we report a case of perioperative continuous hemodynamic monitoring with a long term-implanted device in a potential heart transplant patient.

Technical performance of colonoscopy in patients sedated with nurse-administered propofol

OBJECTIVES

Nurse-administered propofol has gained attention as a safe and effective means of sedation for patients undergoing endoscopic procedures. However, little is known about the effect of propofol on the technical performance of colonoscopy.

METHODS

Three separate studies were conducted. In the first study, we reviewed procedure notes from consecutive colonoscopies performed by a single experienced endoscopist at our hospital endoscopy unit on patients sedated with either nurse-administered propofol (n = 162) or midazolam/narcotic (n = 164). In the second study, 100 eligible colonoscopy outpatients were randomized to receive either nurse-administered propofol (n = 50) or midazolam/fentanyl (n = 50). In both studies, the measured parameters included visualization of the cecum, time required to reach the cecum, repositioning of the patient, and the application of abdominal counterpressure. In a third study, we reviewed the rate of cecal intubation and colonic perforation in the first 2357 patients in our unit receiving nurse-administered propofol.

RESULTS

In the retrospective comparative study, there was no difference in the cecal intubation rate in those receiving propofol (99.4%) compared to those receiving midazolam/narcotic (97%; p= 0.1), and three of five failed cecal intubations in the latter group resulted from obstructing masses. Patients sedated with propofol were repositioned less frequently compared to those receiving midazolam/narcotic (3.7%vs 26.2%) (p < 0.0001). Abdominal pressure was employed in 9.9% of patients sedated with propofol compared to 19.5% (p= 0.01) of those given midazolam/narcotic. The mean time to reach the cecum was lower in the propofol group than in the midazolam/narcotic group (4.6 min vs 6.0 min, p= 0.002). In the prospective randomized study, the endoscopist intubated the cecum in all 100 patients. Patients in the propofol group were repositioned less frequently than those in the midazolam/fentanyl group (2%vs 24%, respectively, p= 0.001). The number of cases requiring abdominal counterpressure was not significantly different between the propofol and midazolam/fentanyl groups (12%vs 24%, respectively, p= 0.1). The mean time to reach the cecum in the propofol group (3.2 min) was similar to that in the midazolam/fentanyl group (3.8 min, p= 0.08). Among the first 2357 patients in our unit undergoing colonoscopy with nurse-administered propofol, the rate of complete colonoscopy was 99.2% and there were no perforations.

CONCLUSION

Nurse-administered propofol sedation is safe and simplifies the technical performance of colonoscopy compared to midazolam/narcotic sedation.

Insuffisances cardiaques d’origine médicamenteuse (en dehors des anthracyclines)

The principal drugs implicated in or disclosing cardiac insufficiency are drawn from a review of the literature and observations by the French national pharmacovigilance database, from 1984 to April 2003. Several pharmacological classes are identified: in addition to antimitotic drugs, such as anthracyclines, many drugs are implicated in cardiac insufficiency, e.g. immunomodulators, anti-inflammatory drugs (including coxibs), antiarrhythmic drugs, anaesthetic drugs, antipsychotic drugs, and antidiabetic drugs (including glitazones). It is usual to classify these drugs according to three categories: (i) drugs likely to cause cardiac insufficiency de novo (such as cyclophosphamide, paclitaxel, mitoxantrone, interferons, interleukin-2 etc.); (ii) drugs likely to worsen preexisting cardiac insufficiency (such as antiarrhythmics, beta-blockers, calcium antagonists, nonsteroidal and steroidal anti-inflammatory drugs, sympathomimetic drugs etc.); and (iii) drugs only occasionally causing cardiac insufficiency. This review shows that this classification is, in fact, artificial. If cardiac toxicity is a constant concern when using antimitotic drugs or some immunomodulator drugs, it is advisable to exercise caution in the use of many other drugs when treating patients with cardiac insufficiency, even if the clinical situation is well controlled. In particular, drug-drug interactions and patient medical history must be taken into account.

Synergistic sedation with midazolam and propofol versus midazolam and pethidine in colonoscopies: a prospective, randomized study

OBJECTIVE

The aim of our study was to compare the safety and efficacy of the synergistic sedation with a low dose of midazolam combined with propofol versus the standard regimen of midazolam and pethidine for conscious sedation in colonoscopy in a group of patients that included a sufficient number of elderly patients with several comorbidities.

METHODS

A total of 120 consecutive patients undergoing colonoscopy in a prospective study were randomly assigned to one of two medication regimens (55 patients were over 65 yr). Patients in group A (n = 64) received i.v. 2 mg (<70 kg b.w.) or 3 mg (>70 kg b.w.) of midazolam and a median dose of 80 mg of propofol (range 40-150). Patients in group B (n = 56) received i.v. a median dose of 5 mg of midazolam (range 3-7) and 75 mg of pethidine (range 50-125). The patient's comfort level was assessed by a 4-point scale 24 h after the procedure. The time to recover from sedation was assessed at 5, 10, and 30 min after the procedure by using the Aldrete score.

RESULTS

Multivariate stepwise logistic regression analysis revealed that among sex, age, duration of the test, American Society of Anesthesiologists' Physical Status Classification grade, and the sort of sedation, the synergistic sedation with midazolam and propofol was the only factor associated with a higher level of patient comfort (chi2 = 5.5, p < 0.05). Additional multivariate stepwise logistic regression analysis revealed that among sex, age, duration of the test, American Society of Anesthesiologists' Physical Status Classification grade, and the sort of sedation, the synergistic sedation with midazolam and propofol was the only factor associated with a quicker patient recovery time (chi2 = 24.5, p < 0.01; chi2 = 51.7, p < 0.01; chi2 = 148.4, p < 0.01 for Aldrete in 10 min, 20 min, and 30 min, respectively). The endoscopist's evaluation of patient sedation and cardiorespiratory parameters were similar in both groups and in all age groups.

CONCLUSIONS

Our data suggest that the synergistic sedation with a low dose of midazolam combined with propofol was superior to a standard combination of midazolam and the opioid pethidine for colonoscopies as far as the patient comfort and recovery times are concerned.

Propofol compared with general anesthesia for pediatric GI endoscopy: is propofol better?

BACKGROUND

The objective of this study was to compare the efficacy and safety of propofol and general anesthesia in children undergoing elective GI endoscopy.

METHODS

The study design was prospective, randomized, and open label. Pediatric patients aged 2 to 21 years in whom elective GI endoscopy under general anesthesia was required were randomized to receive propofol or standard inhalational anesthesia. The parameters monitored in the 2 groups were (1) time until wake-up after completion of the procedure, and (2) total time for anesthesia and recovery. Adverse events during the procedures were noted with each agent.

RESULTS

Fifty pediatric patients were recruited, 25 in each group. The mean (SD) time until wake-up in the propofol group was 29.92 (16.01) minutes and 18.52 (10.03) minutes in the anesthesia group, (p = 0.002). With stratification into 4 age groups, it was noted that the youngest children, those 2 to 5 years of age, took the longest to awaken with propofol compared with inhalational anesthesia, whereas in the other age groups the differences were not statistically significant. In contrast, the mean total time for anesthesia and recovery in the propofol group was 107.4 (30.14) minutes and 139 (7.61) minutes in the inhalational anesthesia group (p < 0.004). The total time for anesthesia and recovery was longest in the group 5 to 8 years of age who had inhalational anesthesia (p < 0.01). Changes in systolic and diastolic blood pressure occurred with equal frequency in both groups. Transient apnea was noted in 20% of patients receiving propofol. Restlessness and agitation occurred in 52% of patients receiving inhalational anesthesia compared with 8% in the propofol group (p = 0.001).

CONCLUSIONS

Propofol, administered by an anesthesiologist, is an excellent and safe intravenous anesthetic agent for pediatric GI endoscopy.

Dose-response relationship of propofol on mid-latency auditory evoked potentials (MLAEP) in cardiac surgery

BACKGROUND

Propofol-sufentanil anaesthesia has become popular during cardiac surgery for its titrability and short recovery time. Avoidance of awareness is a major goal during cardiac surgery. We therefore investigated the dose-response relationship of propofol and cortical responses (mid-latency auditory evoked potentials, MLAEP).

METHODS

One hundred patients undergoing cardiac surgery were investigated. Basic anaesthesia was performed with sufentanil (4.5 microg kg(-1) h(-1)) / flunitrazepam (9 microg kg(-1) h(-1)) infusion (control group); the other groups received in addition a loading dose of propofol 2 mg kg(-1) and a maintainance infusion of 1-3.5 mg kg(-1) h(-1). MLAEP were evaluated by using Pa/Nb-amplitudes and Nb-latencies. Haemodynamics were monitored by ECG, arterial blood pressure and cardiac function with pulmonary artery catheterization.

RESULTS

In the control group, median amplitude of MLAEP decreased by 50% with a wide range, but were detectable in >90% of patients throughout surgery. Propofol suppressed amplitude Pa/Nb of MLAEP dose dependently. With 3.5 mg kg(-1) h(-1) amplitudes disappeared in >40% of patients throughout cardiac surgery. Median Nb-latencies increased in the control group from 44 to a range from 50 to 60 ms. In groups with propofol >2 mg kg(-1) h(-1), Nb-latencies, detectable in the patients without complete suppression of MLAEP, increased to median 60 ms. Haemodynamic parameters and cardiac function did not differ among the groups. The use of vasopressors was not increased even with the highest propofol dose used.

CONCLUSION

The dose-response effect of propofol on auditory evoked potentials reveals that combining a loading dose of 2 mg kg-1 with a consecutive infusion of 3.5 mg kg(-1) h(-1) significantly suppresses MLAEP during cardiac surgery. Thus, auditory information may not be processed and awareness with recall becomes unlikely.

Sedation with propofol plus midazolam versus propofol alone for interventional endoscopic procedures: a prospective, randomized study

AIM

Adequate patient sedation is mandatory for most interventional endoscopic procedures. Recent anaesthesiologic studies indicates that propofol and midazolam act synergistically in combination and therefore may be superior to sedation with propofol alone in terms of sedation efficacy, recovery and costs (due to a presumed lower total dose of propofol needed).

METHODS

A total of 239 consecutive patients undergoing therapeutic EGD or ERCP (EGD/ERCP-ratio, 1:1) randomly received either propofol alone (n=120, group A, loading dose 40-60 mg intravenously, followed by repeated doses of 20 mg) or propofol plus midazolam (n=119, group B, initial midazolam dose of 2. 5-3.5 mg intravenously, followed by repeated doses of 20 mg of propofol) for sedation. Vital signs (heart rate, blood pressure, oxygen saturation, electrocardiogram) were continuously monitored. Procedure-related parameters, the recovery time and quality (post-anaesthesia recovery score) as well as the patient's co-operation and tolerance to the procedure (visual analogue scale) were prospectively assessed.

RESULTS

Patients of group A and B were well matched with respect to demographic and clinical data, endoscopic findings, and the type of associated procedures. In group A, a mean dose of 0.25 +/- 0.13 mg.min/kg propofol was used compared to 0.20 +/- 0.09 mg.min/kg of propofol in group B (P < 0.01, plus additional 2.9 +/- 0.5 mg of midazolam). Clinically relevant changes in vital signs were observed at comparable frequencies with a lowering of the systolic blood pressure < 90 mmHg in six out of 119 patients in group B and one out of 120 patients in group A (P=0.07). The sedation efficacy was rated similarly in both groups, whereas the mean recovery time (group A, 19 +/- 7 min vs. group B, 25 +/- 8 min, P < 0.05) as well as the recovery score (post-anaesthesia recovery score group A, 8.0 +/- 1.1 vs. post-anaesthesia recovery score group B, 7.3 +/- 1.2, P < 0.001) were significantly better with propofol alone than with propofol plus midazolam.

CONCLUSION

During therapeutic endoscopy, sedation with propofol and midazolam requires a lower total dose of propofol, but otherwise has no superior sedation efficacy and is associated with a slower post-procedure recovery than sedation with propofol alone.

Less adrenergic activation during cataract surgery with total intravenous than with local anesthesia

BACKGROUND

Previous studies reported that, contrary to local anesthesia, cataract surgery under inhalational anesthesia is associated with substantial adrenergic activation. We tested the hypothesis that total intravenous anesthesia (TIVA) with propofol and alfentanil produces less or comparable adrenergic activation during cataract surgery than local anesthesia.

METHODS

Patients were randomly assigned to peribulbar local block (n=10) or TIVA (n=10). The heart rate, blood pressure, plasma concentrations of catecholamines, cortisol, and glucose were assessed at seven pre-, intra-, and post-operative time points.

RESULTS

In the patients given local anesthesia, plasma concentrations of epinephrine, norepinephrine and cortisol did not change significantly. In contrast, plasma epinephrine decreased by roughly 66% during TIVA: from 45+/-16 to 15+/-8 pg/ml. Plasma norepinephrine concentration decreased by roughly 50%, from 462+/-265 to a minimum value of 219+/-6 pg/ml and plasma cortisol concentrations decreased by roughly 61%, from 16.4 ng/ml to 6.4 ng/ml. Blood pressure and heart rates remained near baseline values during local anesthesia. In contrast, systolic blood pressure decreased by 30% and heart rate by 12 beats/min during TIVA.

CONCLUSION

The presented study and available data clearly suggest that local anesthesia produces the best adrenergic and hemodynamic stability during cataract surgery. Contrary to previously reported results on inhalational anesthesia (thiopentone/enflurane), the TIVA regimen used effectively prevents the adrenergic and metabolic response during cataract surgery.

Effects of the propofol combination anesthesia on the intrinsic blood-clotting system

Fat emulsions can cause changes in blood-clotting and fibrinolysis. The aim of this study was to examine the relation between the use of the short-acting hypnotic propofol and alteration of the blood clotting system. In a double-blind randomized study, 36 patients with an aortocoronary bypass operation were given either midazolam/fentanyl or propofol/alfentanil. Eleven blood samples were taken at fixed times pre-, intra- and postoperatively to determine changes caused by the anesthetic agents on the hemostaseologic parameters during the whole operation. Perioperative blood pressures of both groups were measured at seven fixed points. From the beginning of the extracorporeal circulation (ECC) to the end of the operation, the measured values of the factor XIIa- and kallikrein-like activity in the propofol group were significantly higher than those of the midazolam group. Also the values of the kallikrein inhibition capacity and the indicators of fibrinolysis (t-PA and D-dimers) suggest a stronger activation of the contact phase at the start of the recirculation and as a result of it a stronger fibrinolysis within the propofol group. Besides, the hypotensive side-effect in the propofol group was evident in contrast to the midazolam group. With this investigation, a correlation between the application of propofol/alfentanil, contact phase activation with activation of the kallikrein-kinin-bradykinin system and the observed hypotension can be set up.

Drug-induced heart failure

Heart failure is a clinical syndrome that is predominantly caused by cardiovascular disorders such as coronary heart disease and hypertension. However, several classes of drugs may induce heart failure in patients without concurrent cardiovascular disease or may precipitate the occurrence of heart failure in patients with preexisting left ventricular impairment. We reviewed the literature on drug-induced heart failure, using the MEDLINE database and lateral references. Successively, we discuss the potential role in the occurrence of heart failure of cytostatics, immunomodulating drugs, antidepressants, calcium channel blocking agents, nonsteroidal anti-inflammatory drugs, antiarrhythmics, beta-adrenoceptor blocking agents, anesthetics and some miscellaneous agents. Drug-induced heart failure may play a role in only a minority of the patients presenting with heart failure. Nevertheless, drug-induced heart failure should be regarded as a potentially preventable cause of heart failure, although sometimes other priorities do not offer therapeutic alternatives (e.g., anthracycline-induced cardiomyopathy). The awareness of clinicians of potential adverse effects on cardiac performance by several classes of drugs, particularly in patients with preexisting ventricular dysfunction, may contribute to timely diagnosis and prevention of drug-induced heart failure.

Comparison of propofol and methohexital continuous infusion techniques for conscious sedation

PURPOSE

Methohexital and propofol have been shown to be effective agents for continuous intravenous infusion to produce conscious sedation during oral surgical procedures. The current study was conducted to compare these techniques for intraoperative cardiopulmonary stability, patient cooperation, amnesia, comfort, recovery time, and postoperative nausea and vomiting.

METHODS

Seventy ASA Class I or Class II patients between the ages of 18 and 40 years, scheduled for surgical extraction of impacted third molars, were entered into the study. Thirty-five patients were assigned to group A (methohexital) and 35 were assigned to group B (propofol). Intravenous sedation was accomplished using premedication with 1.5 microg/kg of fentanyl and 0.05 mg/kg of midazolam followed by the continuous infusion of methohexital or propofol at a rate of 50 microg/kg/min. The infusion was then titrated to 100 microg/kg/min to accomplish a level of sedation in which the eyes were closed and the patients were responsive to verbal commands. Subjects were monitored for variability of heart rate, blood pressure, oxygen saturation, amnesia, comfort, cooperation, nausea and vomiting, and recovery time based on cognitive, perceptual, and psychomotor tests.

RESULTS

There was no statistical difference between the two medication groups except for heart rate, which was found to increase by 11 beats/min for group A and only three beats/min in group B.

CONCLUSION

A continuous infusion technique using either methohexital or propofol (50 to 100 microg/kg/min) was found to be safe and effective, with no clinically significant differences in cooperation, cardiopulmonary stability, recovery time, amnesia, comfort, and the incidence of nausea or vomiting. However, the cost-effectiveness of methohexital is superior to that of propofol.

Effects of the combinations propofol/alfentanil and midazolam/fentanyl on blood pressure and contact phase system during coronary surgery

Perioperative haemodynamic changes leading to severe circulatory problems during open-heart surgery still represent dreaded complications. The aim of this study was to examine the relationship between the use of applied anaesthetic agents and alterations of the contact phase of the intrinsic blood-clotting system, as changes within the kallikrein-kinin system can lead to a fall in blood pressure. In a randomized study, parameters of the kallikrein-kinin system, coagulation and fibrinolysis were determined for 36 patients with aortocoronary bypass operations. The patients had been given either midazolam/fentanyl or propofol/alfentanil to maintain anaesthesia. Perioperative blood pressure values were registered at seven fixed points. The measured values of the factor XIIa-like activity and the kallikrein-like activity suggested a higher activation of the contact phase, when propofol/alfentanil was given. From the start of the extracorporeal circulation (ECC) to the end of the operation, the kallikrein-like activities in the propofol/alfentanil group were significantly higher than those of the midazolam/fentanyl group. Also, the results of the kallikrein inhibition capacity and the indicators of fibrinolysis (t-PA and D-dimers) indicate a stronger activation of the contact phase--at least at the beginning of recirculation--and as a result of it, a stronger fibrinolysis within the propofol/alfentanil group. In addition, the hypotensive side-effects differed significantly between the two groups. Patients receiving propofol/alfentanil needed the triple amount of antihypotonicum to maintain the mean arterial blood pressure above 75 mmHg. With the results of this study, a correlation between the application of propofol/alfentanil, contact phase activation, with activation of the kallikrein-kinin-bradykinin system and the observed hypotension, can be presumed.

Outpatient general anesthesia: a comparison of a combination of midazolam plus propofol and propofol alone

STUDY OBJECTIVE

To compare the hemodynamics, efficacy, safety, and postoperative recovery of patients following the use of either midazolam plus propofol or placebo plus propofol for induction and maintenance of general anesthesia for outpatient surgical procedures of less than two hours' duration.

DESIGN

Prospective, parallel, randomized, double-blind, placebo-controlled, multicenter study.

SETTING

Ten outpatient surgery centers.

PATIENTS

203 ASA physical status I, II, and III patients undergoing various outpatient surgical procedures.

INTERVENTIONS

Patients were randomly assigned to one of the two treatment groups. For induction of anesthesia, Group 1 received midazolam (0.077 +/- 0.0021 mg/kg) via slow intravenous (IV) push plus continuous infusion propofol (provided in a concentration of 5 mg/ml), and Group 2 received placebo plus full-concentration (10 mg/ml) propofol. Thereafter, Group 1 received half-concentration propofol and Group 2 received full-concentration propofol via continuous infusion for maintenance of anesthesia. Investigators administered doses of study medication in a blinded fashion as required to achieve the desired clinical effect. Drugs used to maintain anesthesia were restricted to study drug, short-acting opioids, and nitrous oxide. Succinylcholine chloride or vecuronium were used to facilitate intubation of study patients.

MEASUREMENTS AND MAIN RESULTS

There were no statistically significant differences between the midazolam/propofol and placebo/propofol groups with respect to the mean (SE) decrease in mean arterial pressure from pre-dose to time of intubation or from time of intubation to initiation of surgery; the mean (SE) time required from initiation of study medication to completion of intubation [6.7 (0.23) minutes vs. 7.0 (0.26) minutes, respectively]; or the mean (SE) amount of propofol required to induce and maintain anesthesia [6.03 (0.329) mg/kg vs. 9.71 (0.489) mg/kg, respectively]. There was no significant difference between the two treatment groups in the time to recovery following the completion of surgery (as assessed by Aldrete Post Anesthesia Recovery Score). Most patients (approximately 79%) in both groups rated the quality of the anesthetic regimen as excellent; however, as assessed by patient questionnaires, fewer patients in the midazolam/ propofol group were able to recall the events surrounding their surgical procedure as compared with patients in the placebo/ propofol group (89.2% vs. 77.9%; p = 0.022). There were no differences between the two groups with respect to the frequency or severity of adverse events.

CONCLUSIONS

Concomitantly administered midazolam and reduction-concentration propofol did not exacerbate the well-described hypotensive effects of full-strength propofol during induction of anesthesia. The time to intubation was equivalent with the combination of midazolam/propofol as compared with propofol alone. Recovery from the two regimens was not significantly different. However, reduced recall of perioperative events was observed more often in the midazolam/propofol regimen compared with propofol alone.

A pharmacokinetically based propofol dosing strategy for sedation of the critically ill, mechanically ventilated pediatric patient

OBJECTIVE

To assess the pharmacokinetics and pharmacodynamics of propofol sedation of critically ill, mechanically ventilated infants and children.

DESIGN

A prospective clinical study.

SETTING

A pediatric intensive care unit (ICU) in a university hospital.

PATIENTS

Clinically stable, mechanically ventilated pediatric patients were enrolled into our study after residual sedative effects from previous sedative therapy dissipated and the need for continued sedation therapy was defined. Patients were generally enrolled just before extubation.

INTERVENTIONS

A stepwise propofol dose escalation scheme was used to determine the steady-state propofol dose necessary to achieve optimal sedation, as defined by the COMFORT scale, a validated scoring system which reliably and reproducibly quantifies a pediatric patient's level of distress. When in need of continued sedation, study patients received an initial propofol loading dose of 2.5 mg/kg and were immediately started on a continuous propofol infusion of 2.5 mg/kg/hr. The propofol infusion rate was adjusted and repeat loading doses were administered, if needed, using a coordinated dosing scheme to maintain optimal sedation for a 4-hr steady-state period. After 4 hrs of optimal sedation, the propofol infusion was discontinued and simultaneous blood sampling and COMFORT scores were obtained until the patient recovered. Additional blood samples were obtained up to 24 hrs after stopping the infusion and analyzed for propofol concentration by high-performance liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

Twenty-nine patients were enrolled into this study. One patient was withdrawn from this study because of an acute decrease in blood pressure occurring with the first propofol loading dose; 28 patients completed the study. All patients were sedated immediately after the first 2.5-mg/kg propofol loading dose. Eight patients were adequately sedated with the starting propofol dose regimen, whereas five patients required downward dose adjustment and 11 patients required dosage increases to achieve optimal sedation. Four patients failed to achieve adequate sedation after five dose escalations and the drug was stopped. Recovery from sedation (COMFORT score of > or = 27) after stopping the propofol infusion was rapid, averaging 15.5 mins in 23 of 24 evaluable patients. In 13 patients who were extubated after stopping the propofol infusion, the time to extubation was also rapid, averaging 44.5 mins. Determination of the blood propofol concentration at the time of recovery from propofol sedation was possible in 15 patients. The blood propofol concentration was variable, ranging between 0.262 to 2.638 mg/L but < or = 1 mg/L in 13 of 15 patients. Similarly, tremendous variation was observed in propofol pharmacokinetics. Propofol disposition was best characterized by a three-compartment model with initial rapid distribution into a small central compartment, V1, and two larger compartments, V2 and V3, which are two-and 20-fold greater in volume, respectively, than V1. Redistribution from V2 and V3 into V1 was much slower than ingress, underscoring the importance of the propofol concentration in V1 as reflective of the drug's sedative effect. Propofol was well tolerated. Two patients experienced an acute decrease in blood pressure which resolved without treatment.

CONCLUSIONS

We conclude that a descending propofol dosing strategy, which maintains the propofol concentration constant in the central compartment (V1) while drug accumulates in V2 and V3 to intercompartmental steady-state, is necessary for effective propofol sedation in the pediatric ICU. Our proposed dosing scheme to achieve and maintain the blood propofol concentration of 1 mg/L would appear effective for sedation of most clinically stable, mechanically ventilated pediatric patients.

Changes in intraocular pressure during low dose intravenous sedation with propofol before cataract surgery

AIMS

This study examined the effects on intraocular pressure, pulse rate, and blood pressure of low dose intravenous sedation with propofol.

METHODS

Twenty adult patients who were scheduled to undergo cataract surgery were given a single intravenous bolus (0.98 (SEM 0.4) mg/kg) of propofol for sedation before administering the local anaesthetic for cataract surgery. A small intravenous dose of lignocaine was the only other anaesthetic or sedative agent given. The intraocular pressure in the non-surgery eye, the pulse rate, and the blood pressure were measured before and after propofol induction.

RESULTS

Compared with the preinduction baseline, there was a 17% to 27% (from 16.2 (0.7) mm Hg to 11.8 (0.7) mm Hg) decrease in intraocular pressure after propofol induction. A significant decrease in intraocular pressure occurred within the first minute and was still evident at 7 minutes when the measurements were stopped. There was also a 7%-12% increase in pulse rate during the first 4 minutes, a 12% decrease in mean systolic blood pressure, and a 7% decrease in mean diastolic blood pressure from baseline after propofol induction.

CONCLUSION

A single low dose bolus of propofol used for sedation before cataract surgery caused a moderate reduction in intraocular pressure with minimal, easily managed side effects.

Propofol. An overview of its pharmacology and a review of its clinical efficacy in intensive care sedation

Propofol is a phenolic derivative that is structurally unrelated to other sedative hypnotic agents. It has been used extensively as an anaesthetic agent, particularly in procedures of short duration. More recently it has been investigated as a sedative in the intensive care unit (ICU) where it produces sedation and hypnosis in a dose-dependent manner. Propofol also provides control of stress responses and has anticonvulsant and amnesic properties. Importantly, its pharmacokinetic properties are characterised by a rapid onset and short duration of action. Noncomparative and comparative trials have evaluated the use of propofol for the sedation of mechanically ventilated patients in the ICU (postsurgical, general medical, trauma). Overall, propofol provides satisfactory sedation and is associated with good haemodynamic stability. It produces results similar to or better than those seen with midazolam or other comparator agents when the quality of sedation and/or the amount of time that patients were at adequate levels of sedation are measured. Patients sedated with propofol also tend to have a faster recovery (time to spontaneous ventilation or extubation) than patients sedated with midazolam. Although most studies did not measure time to discharge from the ICU, propofol tended to be superior to midazolam in this respect. In a few small trials in patients with head trauma or following neurosurgery, propofol was associated with adequate sedation and control of cerebral haemodynamics. The rapid recovery of patients after stopping propofol makes it an attractive option in the ICU, particularly for patients requiring only short term sedation. In short term sedation, propofol, despite its generally higher acquisition costs, has the potential to reduce overall medical costs if patients are able to be extubated and discharged from the ICU sooner. Because of the potential for hyperlipidaemia and the development of tolerance to its sedative effects, and because of the reduced need for rapid reversal of drug effects in long term sedation, the usefulness of propofol in long term situations is less well established. While experience with propofol for the sedation of patients in the ICU is extensive, there are still areas requiring further investigation. These include studies in children, trials examining cerebral and haemodynamic outcomes following long term administration and in patients with head trauma and, importantly, pharmacoeconomic investigations to determine those situations where propofol is cost effective. In the meantime, propofol is a well established treatment native to benzodiazepines and/or other hypnotics or analgesics when sedation of patients in the ICU is required. In particular, propofol possesses unique advantages over these agents in patients requiring only short term sedation.

Timing of tracheal extubation in adult cardiac surgery patients

In this article, we examine 14 studies conducted from 1974 to 1994 on "early" endotracheal extubation (0 to 12 hours postoperatively) in adult cardiac surgery patients. Aspects reviewed include: criteria for patient selection; criteria for extubation; analyses of feasibility and safety; effects of anesthetic technique; and patient morbidity. Advantages and disadvantages of early or "fast-track" extubation are discussed as are directions for future research. Selection criteria varied among studies; patients were most commonly excluded because of severe, preexisting pulmonary disease or ventricular dysfunction. Based on the studies examined, however, at least 70% to 80% of adult patients would meet selection criteria. Three universal criteria were applied in all studies: (1) patient is awake and responsive; (2) adequate gas exchange while breathing spontaneously; and (3) cardiovascular stability. To facilitate early extubation in appropriately selected patients, the choice of anesthetic technique and postoperative sedation technique appears to be important. Anesthetic techniques based on inhalational anesthetic agents, supplemented by moderate doses of narcotics, are more appropriate than high-dose narcotic anesthesia for early extubation protocols. Postoperative sedation with propofol, which has a rapid offset of action, may be particularly advantageous. Every published investigation has concluded that early extubation is safe, feasible, and desirable. Morbidity and mortality have not been shown to be affected by early extubation. Anesthetic technique and the patient's medical condition are the two major factors to consider in accomplishing early extubation.

Propofol sequestration within the extracorporeal circuit

Various drugs administered during cardiac anaesthesia are sequestered in the extracorporeal circuit in vitro, but it is uncertain whether this sequestration phenomenon affects plasma drug concentration in vivo. The present study was undertaken to evaluate (1) in vitro sequestration of propofol in the extracorporeal circuit and (2) whether the change in plasma propofol concentration induced by initiation of cardiopulmonary bypass in vivo can be explained by haemodilution. For the in vitro evaluation, three separate experiments with a closed circuit (membrane oxygenator, reservoir, and tubings) were performed. The pH and PCO2 of the circulating solution (a mixture of Ringer's acetate and whole blood) were maintained within the normal physiological range, and the temperature of the solution was 28 degrees C. The solution was circulated at a flow of 4 L.min-1 and propofol was added to the solution to achieve a concentration of 2 micrograms.ml-1. Serial samples were taken from the circulating solution for measurement of propofol concentration by high performance liquid chromatography. In the in vivo part of the study, 14 patients received a continuous infusion of propofol, and samples for the determination of plasma propofol concentration and blood haematocrit were taken before and five and ten minutes after initiation of cardiopulmonary bypass. In vitro, at 5 and 120 min after addition of propofol into the circulating solution, approximately 65% and 25%, respectively, of the predicted propofol level was measurable in the solution.(ABSTRACT TRUNCATED AT 250 WORDS)