Attenuation of Acute Lung Injury with Propofol in Endotoxemia

Endotoxin causes acute lung injury (ALI) through many mediators of inflammatory and immune responses. Propofol is an antiinflammatory and immunosuppressive drug. We conducted this study to evaluate whether propofol attenuates ALI associated with endotoxemia. Thirty-two anesthetized rabbits were randomly divided into four groups (n = 8 each). ALI was induced by IV endotoxin 5 mg/kg over 30 min in 3 groups. In 2 of the ALI groups, IV administration of propofol (2 or 5 mg/kg as a bolus followed by continuous infusion at 4 or 15 mg x kg(-1) x h(-1)) was started 15 min before endotoxin. The other ALI group received soybean-oil emulsion. The nonlung injury control group received infusion of both vehicles. The lungs were mechanically ventilated with 40% oxygen for 6 h after endotoxin. Hemodynamics did not differ among groups. The large dose of propofol attenuated lung leukosequestration, pulmonary edema (as assessed by lung wet/dry weight ratio), and pulmonary hyperpermeability (as assessed by albumin levels in bronchoalveolar lavage fluid) and resulted in better oxygenation, lung mechanics, and histological change. The small dose of propofol failed to do so. Our findings suggest that a large dose of propofol successfully mitigates physiological, biochemical, and histological deterioration in ALI in endotoxemia.

The efficiency of different adjunct techniques for regional anesthesia

In the present prospective, randomized controlled trial, 110 unpremedicated patients undergoing orthopedic surgery under regional anesthesia were randomly divided into 5 groups, with 22 patients in each. During the operation, group 1 listened to a pre-recorded explanation and music, group 2 listened to a subliminal sound, group 3 received propofol by patient-controlled sedation (PCS), group 4 received intravenous midazolam, and group 5 was the control group. Patients in the midazolam group were significantly more sedated than the control group at 1 hr into the operation. The group that listened to an explanation and music were significantly less satisfied than the propofol group at the end of the operation and 30 min. postoperatively. An incremental cost-effectiveness ratio showed that if explanation and music are used instead of propofol it would save 299.53 baht per patient, but the patient satisfaction score will be 17.26 points lower than if the more expensive drug is used.

Peroperative depth of anaesthesia may influence postoperative opioid requirements

BACKGROUND

Studies on monitoring the depth of anaesthesia have shown that with the use of these monitors the peroperative consumption of anaesthetics can be reduced. Studies have also indicated that the peroperative depth of anaesthesia may affect the postoperative course. The purpose of this study was to evaluate a possible relation between the depths of anaesthesia and the postoperative pain score and consumption of morphine.

METHODS

We used middle latency auditory evoked potentials (MLAEPs) for monitoring the depth of anaesthesia. The study was prospective, observer blinded and included 50 women scheduled for elective abdominal hysterectomy. Anaesthesia was induced using propofol and remifentanil. Before leaving the recovery room the patients were provided with a programmed patient-controlled pump (PCA), which was only activated on demand. Auditory evoked potentials were registered from just before induction of anaesthesia and during the whole procedure, but the anaesthetist did not have access to the monitor.

RESULTS

Fifty patients were included and seven were excluded. The remaining 43 patients were divided into two groups: Group High (n=12) with an AAI>28 for >5% of the registration time and Group Low (n=31) with an AAI>28 for <5% of the registration time. Group High had significantly higher morphine requirements in the recovery and activated the PCA-pump more frequently during the first 24 postoperative hours.

CONCLUSION

The results indicate that the peroperative depth of anaesthesia may have effects on the postoperative analgesic requirements.

Behavioural phenotypes of hypomorphic KCC2-deficient mice

Hyperpolarizing fast inhibitory neurotransmission by gamma-aminobutyric acid and glycine requires an efficient chloride extrusion mechanism in postsynaptic neurons. A major effector of this task in adult animals is the potassium-chloride co-transporter KCC2 that is selectively and abundantly expressed postsynaptically in most CNS neurons. Yet, the role of KCC2 in adult brain at the systems level is poorly known. Here, we characterize the behaviour of mice doubly heterozygous for KCC2 null and hypomorphic alleles that retain 15-20% of normal KCC2 protein levels in the brain. These hypomorphic KCC2-deficient mice were viable and fertile but weighed 15-20% less than wild-type littermates at 2 weeks old and thereafter. The mice displayed increased anxiety-like behaviour in several tests including elevated plus-maze and were more susceptible to pentylenetetrazole-induced seizures. Moreover, the mice were impaired in water maze learning and showed reduced sensitivity to tactile and noxious thermal stimuli in von Frey hairs, hot plate and tail flick tests. In contrast, the mice showed normal spontaneous locomotor activity in open field and Y-maze tests, and intact motor coordination in rotarod and beam tests. The results suggest that requirements for KCC2-dependent fast hyperpolarizing inhibition may differ among various functional systems of the CNS. As shunting inhibition is expected to be intact in KCC2-deficient neurons, these mice may provide a useful tool to study the specific functions and relative importance of hyperpolarizing fast synaptic inhibition in adult CNS that may have implications for human neuropsychiatric disorders, such as epilepsy, pain and anxiety.

Impact of the AEP-Monitor/2-derived composite auditory-evoked potential index on propofol consumption and emergence times during total intravenous anaesthesia with propofol and remifentanil in children

BACKGROUND

The composite auditory evoked potential index (cAAI), derived from the AEP Monitor/2 (version 1.6; Danmeter A/S, Odense, Denmark) is a measure of the hypnotic component of general anaesthesia. The purpose of this study was to evaluate the impact of cAAI guidance on propofol consumption and emergence times in children receiving total intravenous anaesthesia (TIVA) with propofol and remifentanil.

METHODS

Twenty children, aged 3-11 years, scheduled for strabismus repair under TIVA with propofol and remifentanil were enrolled. Remifentanil was given to all patients at a constant infusion rate of 0.3 microg kg(-1) min(-1) throughout the anaesthesia. Patients were randomly allocated to receive a continuous propofol infusion adjusted either according to a conventional clinical practice (Group C, n = 10) or guided by cAAI-monitoring (Group G, n = 10, target cAAI 25-35). All patients were connected to the AEP Monitor/2, but in group C the anaesthetist was blinded to cAAI values. Propofol consumption (mgkg(-1)h(-1)) and emergence times (min) were the primary and secondary outcome measures.

RESULTS

Propofol consumption and emergence times (mean +/- SD) were significantly lower in group G compared to group C (Propofol: G: 4.2 +/- 1.7 vs. C 6.4 +/- 1.3 mg kg(-1) h(-1); P < 0.01; emergence times: G: 5.1 +/- 3.7 vs. C 13.2 +/- 8.2 min; P < 0.01). Intraoperative cAAI values (median [interquartile range]) were significantly higher in group G (23.9 [18-29.7]) than in group C (18.4 [16.0-22.1]; P < 0.01). Haemodynamic variables remained stable within age-related limits, and there were no observations of adverse events, especially no clinical signs of intraoperative awareness in any patient.

CONCLUSION

Composite auditory evoked potential index monitoring during propofol/remifentanil-TIVA in children results in reduced propofol consumption and faster emergence.

Less postoperative nausea and vomiting after propofol + remifentanil versus propofol + fentanyl anaesthesia during plastic surgery

BACKGROUND

The effect of different opioids on postoperative nausea and vomiting (PONV) has not been conclusively determined yet, thus the aim of this study was to compare the incidence of PONV in propofol-anaesthetized patients receiving either fentanyl or remifentanil as opioid supplement.

METHODS

Sixty ASA physical status I and II patients scheduled for plastic surgery gave their written informed consent for this prospective, randomized, double-blind study. Anaesthesia was induced with propofol, rocuronium and fentanyl (n = 30; 2 microg kg(-1)) or remifentanil (n = 30; 1 microg kg(-1)). After tracheal intubation, anaesthesia was maintained with propofol, oxygen in air and an infusion of the opioid studied, which was modified according to clinical criteria. Baseline postoperative analgesia was achieved with intravenous propacetamol + metamizol. Intravenous morphine was given if visual analogic scale (VAS) for pain was > or = 4 (scale 0-10) and metoclopramide was administered if a patient presented > or = 2 PONV episodes (nausea or vomiting) in less than 30 min. Postoperatively (2, 12 and 24 h), we registered VAS, rescue morphine consumption, number of patients with episodes of PONV and number of patients requiring metoclopramide. P < 0.05 was considered significant.

RESULTS

There were no significant differences between groups in the demographic parameters, ASA physical status, propofol dose, VAS, and rescue morphine requirements. Fourteen patients in the fentanyl group and four in the remifentanil group presented PONV episodes 2-12 h postoperative hours' interval; (P < 0.05). Ten patients in the fentanyl group and four in the remifentanil group presented vomiting episodes in the same period (P < 0.05); and eight patients in the fentanyl group and one in the remifentanil group required metoclopramide; (P < 0.05). The number of postoperative PONV episodes were low, both in the 0-2-h period (n = 2 vs. n = 1, fentanyl and remifentanil, respectively) and in the 12-24-h period (n = 3 vs. n = 1).

CONCLUSION

Propofol + fentanyl anaesthesia resulted in a higher incidence of PONV and requirements of antiemetic drugs in the period between 2 and 12 postoperative hours compared with propofol + remifentanil, in patients undergoing plastic surgery.

Human mediotemporal EEG characteristics during propofol anesthesia

Evidence for a response-control-related kind of declarative memory during deep propofol anesthesia has recently been reported. Connectivity within the mediotemporal lobe (MTL), and in particular rhinal-hippocampal synchronization within the gamma band, has been shown to be crucial for declarative memory formation. Thus, we analyzed EEG recordings obtained from the scalp, as well as directly from within the hippocampus and from the anterior parahippocampal gyrus, which is covered by rhinal cortex, in patients with unilateral temporal lobe epilepsy during propofol anesthesia, which preceded electrode explantation. For the gamma band a power decrease starting with induction of anesthesia was observed at scalp position Cz, but a power increase was detected at MTL locations. In contrast to prior results for sleep recordings, rhinal-hippocampal coherence did not decrease within the gamma band at deeper levels of anesthesia. These findings may represent an indirect electrophysiological correlate of partially intact declarative memory formation during deep propofol sedation. Furthermore, we investigated how well the plasma propofol level, as well as different stages of anesthesia including the burst suppression phase, could be monitored by different spectral as well as by nonlinear EEG measures. We observed that conventional spectral power measures, most prominently those recorded from mediotemporal locations, are most closely correlated with the plasma propofol level, whereas different stages of anesthesia can be distinguished best by nonconventional spectral as well as nonlinear measures.

[Effect of propofol on anti-oxidation capability in the ischemia/reperfusion injury after hepatic ischemia in rabbits]

AIM

To investigate the role of oxygen free radicals (OFR) in hepatic ischemia and reperfusion injury (HI/RI) and effect of propofol on them.

METHODS

The rabbits were randomly divided into three groups (n=10), sham operated group (Control), HIR group(I/R) and HIR + propofol group (PRO). Changes of several parameters which included malondialdehyde (MDA), superoxide dismutase (SOD), xanthine oxidase (XO) and alanine aminotransferase(ALT) were measured before ischemia, 45 minutes after ischemia and 45 minutes after reperfusion in plasma. Meanwhile MDA concentration, SOD, XO activities and ALT value in liver tissue were measured, and the ultrastructure changes in liver tissue were observed under electron microscope at 45 minutes after reperfusion.

RESULTS

As compared with group control, XO, MDA and ALT increased and SOD decreased during HI/RI (P < 0.05 and P < 0.01) in plasma, and XO, MDA increased as well as SOD decreased at 45 minutes after reperfusion (P < 0.05 and P < 0.01) in liver tissue and there were abnormal changes of the hepatic ultrastructure at 45 minutes after reperfusion. Propofol reversed the results of mentioned indices as above markedly (P < 0.05 and P < 0.01).

CONCLUSION

OFR is an important factor during HI/RI, propofol may attenuate hepatic ischemia-reperfusion injury by dropping OFR level (raising SOD activity and dropping XO activity) and antagonizing lipid pe-reoxidation (reducing MDA content).

Requirements of propofol at different end-points without adjuvant and during two different steady infusions of remifentanil

BACKGROUND

Some reports show no interaction between propofol and opioids, whereas others state such interactions. We evaluated the influence of remifentanil on propofol requirements at certain anesthesia end-points.

METHODS

Elective surgical patients were randomly assigned to three groups of 15 patients each. Premedication was with oral diazepam 0.1 mg kg(-1). Patients were blindly given equal volumes of saline or remifentanil (7.5 or 30 microg kg(-1). h(-1)) 1 min before induction of anesthesia with infusion of propofol, 30 mg kg(-1). h(-1). We recorded times to, propofol requirements, and bispectral index at loss of counting (LC), loss of verbal command (LVC), loss of reaction to tetanic stimulation (LRT), and onset of burst suppression pattern (BSP) of electroencephalography.

RESULTS

In the remifentanil groups end-points were attained significantly faster and with lower doses of propofol than in the saline group. BIS-values were significantly different at LRT and BSP end-points.

CONCLUSIONS

We conclude that remifentanil infusion started before induction of propofol anesthesia significantly reduces propofol requirements at all end-points. The results suggest that remifentanil accelerates the hypnotic onset of propofol.

The effects of ketamine and propofol on bacterial translocation in rats after burn injury

BACKGROUND

Bacterial translocation (BT) occurs after thermal injury and may result from an ischemic intestinal insult. The aim of the study was to investigate the effects of ketamine and propofol as anesthetic agents on BT in an animal model of burn injury.

METHODS

Sixty male Wistar Albino rats were randomly assigned to six groups of 10 rats each. Anesthesia was induced and maintained with ketamine in groups 1, 2 and 3 and with propofol in groups 4, 5 and 6 during 6 h. Groups 2, 3, 5 and 6 received 30% total body surface area (TBSA) third-degree burns. Groups 1 and 4 had no burn injury. Then, they were allowed to recover from the anesthesia at the end of 6 h. Mean arterial pressure (MAP) was monitored continuously and maintained within 10% of baseline (before burn injury) levels in all animals. Animals in groups 3 and 6 had a laparotomy to obtain a tissue sample from the terminal ileum for determination of intestinal lipid peroxidation by-product malondialdehyde (MDA) before (baseline) and 6 and 24 h after burn injury (ABI). So these animals were not included in the BT studies. At postburn 24 h, animals in groups 1, 2 and 4, 5 were sacrified and samples were taken from the mesenteric lymph nodes (MLN), liver and spleen for bacteriologic cultures.

RESULTS

The incidence of BT was found to be significantly higher in group 2 than in all the other groups. Bacterial translocation incidence of group 5 was not significantly different from that of groups 4 and 1. Group 5 was associated with a significantly reduced number of enteric organisms per gram of tissue compared to group 2. Baseline MDA contents of groups 3 and 6 were similar. Ileal MDA levels were increased in group 3, but there were no significant changes in group 6 at 6 and 24 h ABI compared to baseline.

CONCLUSION

Our results suggest that propofol as an anesthetic agent may prevent BT by scavenging reactive oxygen species and inhibiting lipid peroxidation in an animal model of burn injury.

Tube tip in pharynx (TTIP) ventilation: simple establishment of ventilation in case of failed mask ventilation

BACKGROUND

Mask ventilation occasionally fails. Alternative readily available and simple methods to establish ventilation in these cases are needed.

METHODS

Retrospective description of cases in which a new technique, tube tip in pharynx (TTIP) ventilation, was employed for restoring ventilation in case of failed facemask ventilation during induction of anaesthesia. The technique involves a standard endotracheal tube and can be performed single-handed: A standard endotracheal tube was placed via the mouth with the tip in the pharynx and the cuff was inflated. By placing the fourth and fifth fingers below the ramus of the mandible, the third finger below the lower lip, the second finger above the upper lip and on one side of the nose and the first finger on the other side of the nose, an open airway is restored. Chin lift is inherent in the grip, thus contributing to opening of the airway.

RESULTS

In all four cases of failed mask ventilation the anaesthetist could establish an open airway and subsequent ventilation without the need for an assistant. There were no indications of gastric insufflation.

CONCLUSION

The TTIP technique established ventilation in all four patients after abandoned facemask ventilation. The technique only involves one person and an endotracheal tube and warrants to be included in the armamentarium of anaesthetists. Further prospective studies are needed to refine the technique and delimit its indications.

Practice of sedation and analgesia in German intensive care units: results of a national survey

Introduction

Sedation and analgesia are provided by using different agents and techniques in different countries. The goal is to achieve early spontaneous breathing and to obtain an awake and cooperative pain-free patient. It was the aim of this study to conduct a survey of the agents and techniques used for analgesia and sedation in intensive care units in Germany.

Methods

A survey was sent by mail to 261 hospitals in Germany. The anesthesiologists running the intensive care unit were asked to fill in the structured questionnaire about their use of sedation and analgesia.

Results

A total of 220 (84%) questionnaires were completed and returned. The RAMSAY sedation scale was used in 8% of the hospitals. A written policy was available in 21% of hospitals. For short-term sedation in most hospitals, propofol was used in combination with sufentanil or fentanyl. For long-term sedation, midazolam/fentanyl was preferred. Clonidine was a common part of up to two-thirds of the regimens. Epidural analgesia was used in up to 68%. Neuromuscular blocking agents were no longer used.

Conclusion

In contrast to the US 'Clinical practice guidelines for the sustained use of sedatives and analgesics in the critically ill adult', our survey showed that in Germany different agents, and frequently neuroaxial techniques, were used.

Measurement of symptom withdrawal severity in a 24-hour period after the anesthesia-assisted rapid opiate detoxification procedure

This study examined the Anesthesia-Assisted Rapid Detoxification (AAROD) procedure and the measurement of withdrawal symptom severity within a 24-hour period. The Clinical Opiate Withdrawal Scale (COWS) was utilized at various time intervals, post detoxification. This study demonstrated that all of the patients who underwent the AAROD procedure had withdrawal symptoms post detoxification in the mild range of severity, unlike like traditional detoxification procedures. Further studies are needed to measure withdrawal symptoms longer than one-day post detoxification and to compare the differences between various detoxification protocols.

GPI-15715 Guilford

GPI-15715 (PQ-1002, Aquavan), a water-soluble prodrug of propofol, is being developed by Guilford, under license from ProQuest, as a potential anesthetic agent. In May 2004, Guilford initiated phase III trials in the US to evaluate the sedative effects of this prodrug in several patient populations.

The relationship between bispectral index and targeted propofol concentration is biphasic in patients with major burns

BACKGROUND

Many pathophysiologic alterations in major burns can cause changes in the distribution of, and perhaps response to, drugs commonly used in anesthesia practice. This study was conducted to assess changes in bispectral index (BIS) caused by increasing the target propofol effect-site concentration during a target-controlled infusion (TCI) in major burns.

METHODS

Eighteen patients, ASA physical status 2 or 3, aged from 20 to 55 years old, weighing 50-70 kg, with major burns, scheduled for elective early escharectomy less than a week after injury were recruited. A further 18 ASA physical status class 1 or 2, non-burns, age, sex- and weight-matched adult patients scheduled for elective surgery under general anesthesia were recruited as controls. During anesthesia induction, target propofol effect-site concentrations were increased by increments of 0.5 microg ml(-1) up to 4.5 microg ml(-1). The BIS responses to each target concentration using TCI were compared in both groups.

RESULTS

In the burns group, significantly greater BIS values relating to increasing propofol TCI were noted at deeper anesthesia when compared with controls; at > or =3.5 microg ml(-1); mean BIS remained at a plateau of about 50. Patients with burns had higher cardiac indices, and lower hemoglobin and albumin concentrations than the controls. They consumed more vecuronium to maintain the same degree of neuromuscular blockade than the controls.

CONCLUSIONS

In major burns, the final biphasic BIS responses appeared to be determined by numerous other variables such as BIS algorithm, TCI performance, and altered propofol pharmacokinetics and pharmacodynamics. According to our results the importance of an individually tailored approach, including careful anesthetic titration, based upon the patient's clinical condition and responses can not be overemphasized.

Propofol: therapeutic indications and side-effects

Propofol (2, 6-diisopropylphenol) is a potent intravenous hypnotic agent which is widely used for the induction and maintenance of anesthesia and for sedation in the intensive care unit. Propofol is an oil at room temperature and insoluble in aqueous solution. Present formulations consists of 1% or 2% (w/v) propofol, 10% soybean oil, 2.25% glycerol, and 1.2% egg phosphatide. Disodium edetate (EDTA) or metabisulfite is added to retard bacterial and fungal growth. Propofol is a global central nervous system depressant. It directly activates GABA(A) receptors. In addition, propofol inhibits the NMDA receptor and modulates calcium influx through slow calcium ion channels. Propofol has a rapid onset of action with a dose-related hypnotic effect. Recovery is rapid even after prolonged use. Propofol decreases cerebral oxygen consumption, reduces intracranial pressure and has potent anti-convulsant properties. It is a potent antioxidant, has anti-inflammatory properties and is a bronchodilator. As a consequence of these properties propofol is being increasingly used in the management of traumatic head injury, status epilepticus, delirium tremens, status asthmaticus and in critically ill septic patients. Propofol has a remarkable safety profile. Dose dependent hypotension is the commonest complication; particularly in volume depleted patients. Hypertriglyceridemia and pancreatitis are uncommon complications. Allergic complications, which may include bronchospasm, have been reported with the formulation containing metabisulfite. In addition, this formulation has been demonstrated to result in the generation of oxygen free radicals. High dose propofol infusions have been associated with the "propofol syndrome"; this is a potentially fatal complication characterized by severe metabolic acidosis and circulatory collapse. This is a rare complication first reported in pediatric patients and believed to be due to decreased transmembrane electrical potential and alteration of electron transport across the inner mitochondrial membrane.

[gamma-Hydroxybutyrate intoxication]

The drug gamma-Hydroxybutyrate (GHB), also known as liquid ecstasy, has now reached Europe. Estimating the dosage of liquid GHB is especially difficult leading to unintentional intoxication because the exact concentration is not known. We repeatedly had to treat young patients intoxicated by GHB in our intensive care unit. We describe the course and treatment of three patients with GHB intoxication. If alcohol or mixed intoxication with drugs detected in traditional hospital toxicological assays has been excluded as the cause of unconsciousness in young patients from disco's, an intoxication with GHB should be considered. The therapy is mainly symptomatic and supportive but monitoring in an intensive care unit with the option of short term respirator therapy is necessary. Serum and urine samples taken on arrival should be conserved for further investigation in a forensic institute.