Pharmacokinetic implications for the clinical use of propofol

Remotely controlled drug release in deep brain regions of non-human primates

Many areas of science and medicine would benefit from selective release of drugs in specific regions. Nanoparticle drug carriers activated by focused ultrasound-remotely applied, depth-penetrating energy-may provide such selective interventions. Here, we developed stable, ultrasound-responsive nanoparticles that can be used to release drugs effectively and safely in non-human primates. The nanoparticles were used to release propofol in deep brain visual regions. The release reversibly modulated the subjects' visual choice behavior and was specific to the targeted region and to the released drug. Gadolinium-enhanced MR imaging suggested an intact blood-brain barrier. Blood draws showed normal clinical chemistry and hematology. In summary, this study provides a safe and effective approach to release drugs on demand in selected deep brain regions at levels sufficient to modulate behavior.

Exploring the Median Effective Dose of Ciprofol for Anesthesia Induction in Elderly Patients: Impact of Frailty on ED50

Purpose

Explore the median effective dose of ciprofol for inducing loss of consciousness in elderly patients and investigate how frailty influences the ED50 of ciprofol in elderly patients.

Patients and Methods

A total of 26 non-frail patients and 28 frail patients aged 65-78 years, with BMI ranging from 15 to 28 kg/m2, and classified as ASA grade II or III were selected. Patients were divided into two groups according to frailty: non-frail patients (CFS<4), frail patients (CFS≥4). With an initial dose of 0.3 mg/kg for elderly non-frail patients and 0.25 mg/kg for elderly frail patients, using the up-and-down Dixon method, and the next patient's dose was dependent on the previous patient's response. Demographic information, heart rate (HR), oxygen saturation (SpO2), mean blood pressure (MBP), and bispectral index (BIS) were recorded every 30 seconds, starting from the initiation of drug administration and continuing up to 3 minutes post-administration. Additionally, the total ciprofol dosage during induction, occurrences of hypotension, bradycardia, respiratory depression, and injection pain were recorded.

Results

The calculated ED50 (95% confidence interval [CI]) and ED95 (95% CI) values for ciprofol-induced loss of consciousness were as follows: 0.267 mg/kg (95% CI 0.250-0.284) and 0.301 mg/kg (95% CI 0.284-0.397) for elderly non-frail patients; and 0.263 mg/kg (95% CI 0.244-0.281) and 0.302 mg/kg (95% CI 0.283-0.412) for elderly frail patients. Importantly, no patients reported intravenous injection pain, required treatment for hypotension, or experienced significant bradycardia.

Conclusion

Frailty among elderly patients does not exert a notable impact on the median effective dose of ciprofol for anesthesia induction. Our findings suggest that anesthesiologists may forego the necessity of dosage adjustments when administering ciprofol for anesthesia induction in elderly frail patients.

Quantitation of propofol metabolites by LC-MS/MS demonstrating long detection window for urine drug monitoring

Introduction

Chromatographic methods for analysis of propofol and its metabolites have been widely used in pharmacokinetic studies of propofol distribution, metabolism, and clearance. Application of chromatographic methods is also needed in clinical and forensic laboratories for detecting and monitoring propofol misuse.

Objective

We report a method for sensitive analysis of propofol, propofol 1-glucuronide (PG), 4-hydroxypropofol 1-glucuronide (1-QG), 4-hydroxypropofol 4-glucuronide (4-QG) and 4-hydroxypropofol 4-sulfate (4-QS) in urine by LC-MS/MS analysis. The method employs a simple dilute-and-analyze sample preparation with stable isotope internal standardization.

Results

Validation studies demonstrate a linear calibration model (100-10,000 ng/mL), with dilution integrity verified for the extended range of concentrations experienced in propofol use. Criteria-based validation was achieved, including an average coefficient of variation of 6.5 % and a percent bias of -4.2 ng/mL. The method was evaluated in 12 surgical patients, with monitoring periods lasting up to 30 days following intravenous propofol administrations of 100-3000 mg on the day of surgery. While the concentration ratio of PG to 4-hydroxy propofol metabolite decreased significantly in the days following surgery, PG maintained the highest concentration in all specimens. Both PG and 1-QG were detectable throughout the monitoring periods, including in a patient monitored for 30 days. Lower concentrations were determined for 4-QG and 4-QS, with evidence of detection up to 20 days. Propofol was not detectable in any urine specimens, thereby proving ineffective for identifying drug use.

Conclusion

The validated method for quantifying propofol metabolites demonstrates its applicability for the sensitive detection of propofol misuse over a long window of drug-use detection.

Implantable Hydrogel-Protective DNA Aptamer-Based Sensor Supports Accurate, Continuous Electrochemical Analysis of Drugs at Multiple Sites in Living Rats

The ability to track the levels of specific molecules, such as drugs, metabolites, and biomarkers, in the living body, in real time and for long durations, would improve our understanding of health and our ability to diagnose, treat, and monitor disease. To this end, we are developing electrochemical aptamer-based (EAB) biosensors, a general platform supporting high-frequency, real-time molecular measurements in the living body. Here we report that the use of an agarose hydrogel protective layer for EAB sensors significantly improves their signaling stability when deployed in the complex, highly time-varying environments found in vivo. The improved stability is sufficient that these hydrogel-protected sensors achieved good baseline stability and precision when deployed in situ in the veins, muscles, bladder, or tumors of living rats without the use of the drift correction approaches traditionally required in such placements. Finally, our implantable gel-protective EAB sensors achieved good biocompatibility when deployed in vivo in the living rats without causing any severe inflammation.

Propofol in ICU Settings: Understanding and Managing Anti-Arrhythmic, Pro-Arrhythmic Effects, and Propofol Infusion Syndrome

Propofol has revolutionized anesthesia and intensive care medicine owing to its favorable pharmacokinetic characteristics, fast onset, and short duration of action. This drug has been shown to be remarkably effective in numerous clinical scenarios. In addition, propofol has maintained an overwhelmingly favorable safety profile; however, it has been associated with both antiarrhythmic and proarrhythmic effects. This review concisely summarizes the dual arrhythmic cardiovascular effects of propofol and a rare but serious complication, propofol infusion syndrome (PRIS). We also discuss the need for careful patient evaluation, compliance with recommended infusion rates, and vigilant monitoring.

General anesthesia with propofol during oocyte retrieval and in vitro fertilization outcomes: retrospective cohort study

General anesthesia is frequently administered during oocyte retrieval. Its effects on the outcomes of IVF cycles are uncertain. This study investigated whether administration of general anesthesia (specifically propofol) during oocyte retrieval affects IVF outcomes. A total of 245 women undergoing IVF cycles were included in this retrospective cohort study. IVF outcomes of 129 women who underwent oocyte retrieval under propofol anesthesia and 116 without anesthesia were compared. Data were adjusted for age, BMI, estradiol on triggering day and total gonadotropin dose. The primary outcomes were fertilization, pregnancy and live birth rates. A secondary outcome was the efficiency of follicle retrieval associated with the use of anesthesia. Fertilization rate was lower in retrievals under anesthesia compared to without (53.4% ± 34.8 vs. 63.7% ± 33.6, respectively; p = 0.02). There was no significant difference in the ratio of expected to retrieved oocytes between retrievals with and without anesthesia (0.8 ± 0.4 vs. 0.8 ± 0.8, respectively, p = 0.96). The differences in pregnancy and live birth rates between the groups were not statistically significant. General anesthesia administered during oocyte retrieval may have adverse effects on the fertilization potential of oocytes. This impact on the developmental potential of oocytes may lead to negative IVF outcomes and should be investigated further.

Association between general anesthesia and contrast-induced encephalopathy after endovascular treatment on neurovascular diseases

Objective

Contrast-induced encephalopathy (CIE) is a rare neurological complication that can occur in the context of various endovascular procedures. Although many potential risk factors for CIE have been reported, it is still unclear whether anesthesia is a risk factor for the occurrence of CIE. The goal of this study was to investigate the incidence of CIE in patients who underwent endovascular treatment under different anesthesia methods and anesthetics administration and to explore whether general anesthesia was a potential risk factor for CIE.

Methods

We retrospectively reviewed available clinical data from 1,043 patients with neurovascular diseases undergoing endovascular treatment between June 2018 and June 2021 in our hospital. A propensity score-based matching strategy and logistic regression were used to analyze the association between anesthesia and the occurrence of CIE.

Results

In this study, we implemented the embolization of intracranial aneurysm in 412 patients, stent implantation of extracranial artery stenosis in 346, stent implantation of intracranial artery stenosis in 187, embolization of cerebral arteriovenous malformation or dural arteriovenous fistula in 54, endovascular thrombectomy in 20, and other endovascular treatments in 24. A total of 370 patients (35.5%) received treatment under local anesthesia, while the remaining 673 (64.5%) underwent treatment under general anesthesia. In total, 14 patients were identified as CIE, resulting in a total incidence rate of 1.34%. After propensity score-based matching of anesthesia methods, the occurrence of CIE was significantly different between the general anesthesia and local anesthesia group (P = 0.007). After propensity score-based matching of CIE, the anesthesia methods were significantly different between the two groups. Pearson contingency coefficients and logistic regression showed a significant correlation between general anesthesia and the risk of CIE.

Conclusion

General anesthesia might be a risk factor for CIE, and propofol might be associated with the increased occurrence of CIE.

Influence of body fatness on propofol requirements for loss of consciousness in target-controlled infusion: A STROBE-compliant study

This prospective observational study evaluated the effects of body fat on the pharmacologic effect of propofol. Hundred patients aged 18 to 75 years who were scheduled to undergo orthopedic surgery under regional block were enrolled. All participants underwent bioelectrical impedance analysis and were allocated into 2 groups: the high and normal adiposity group, according to percent body fat. Following successful regional block, propofol was incrementally infused until loss of consciousness (LOC) with a target-controlled infusion pump. The effect-site concentration of propofol at LOC and the total infused dose of propofol per total body weight until LOC were recorded. At the end of the surgery, the infusion of propofol was stopped. The elapsed time to recovery of consciousness (ROC) and the effect-site concentration at ROC were recorded. These pharmacologic data were compared between 2 groups. The effect-site concentration of propofol at LOC (µg/mL) was significantly lower in the high adiposity group than in the normal group in both sexes (3.5 ± 0.4 vs 3.9 ± 0.6; P = .020 in males, and 3.4 [interquartile range: 2.9-3.5] vs 3.8 [interquartile range: 3.3-3.9]; P = .006 in females). Total dose per total body weight until LOC (mg/kg) were also significantly lower in the high adiposity group than in the normal group. There was no significant difference in the data related to ROC. The pharmacologic effects of propofol may be affected by the composition of body components. The concentration of propofol using a target-controlled infusion system may be diminished in patients with a high proportion of body fat.

Direct visualization of general anesthetic propofol on neurons by stimulated Raman scattering microscopy

The consensus for the precise mechanism of action of general anesthetics is through allosteric interactions with GABA receptors in neurons. However, it has been speculated that these anesthetics may also interact with the plasma membrane on some level. Owing to the small size of anesthetics, direct visualization of these interactions is difficult to achieve. We demonstrate the ability to directly visualize a deuterated analog of propofol in living cells using stimulated Raman scattering (SRS) microscopy. Our findings support the theory that propofol is highly concentrated and interacts primarily through non-specific binding to the plasma membrane of neurons. Additionally, we show that SRS microscopy can be used to monitor the dynamics of propofol binding using real-time, live-cell imaging. The strategy used to visualize propofol can be applied to other small molecule drugs that have been previously invisible to traditional imaging techniques

•

Multi-modal SRS developed for real-time biological imaging of small molecule substances

•

Propofol primarily concentrates at the cell membrane of neurons

•

Anesthesia dynamics can be monitored in real-time with SRS

Can Propofol Be Used to Assess the Presence of the Rectoanal Inhibitory Reflex During Anorectal Manometry Studies?

OBJECTIVES

To study changes in intra-anal pressure (IAP) and characteristics of the rectoanal inhibitory reflex (RAIR) during anorectal manometry (ARM) in patients undergoing anesthesia induction with propofol.

METHODS

Prospective study in which ARM was performed at baseline while patients were awake and repeated after propofol-induced anesthesia. We studied IAP and the presence and characteristics of the RAIR before and after propofol.

RESULTS

A total of 27 patients were included (63% male; 9.2 years). Three patients had obstructive symptoms after Hirschsprung disease repair (HSCR), and 24 had intractable constipation. At baseline, the RAIR was present on 21 of 27 patients and absent on 6 of 27. Of the six patients with an absent RAIR, it remained absent in four of six (three known HSCR, and one new diagnosis of IAS achalasia), and two of six had a normal RAIR during propofol. Therefore, RAIR was present in all patients with constipation. The mean resting IAP was significantly lower after propofol. The percentage of IAS relaxation after lower balloon volume inflations was significantly higher during propofol (P < 0.05). No difference was observed over the latency time or the total relaxation time after propofol.

CONCLUSIONS

Propofol can be used to assess the presence of the RAIR during ARM in children who are uncooperative and undergoing other procedures under anesthesia. On the other hand, propofol significantly reduces the resting IAP and increases the percentage of internal anal sphincter relaxation after balloon distention. These findings may impact the interpretation to decide if an intervention is needed, or if there is a possible spinal neuropathy.

Sedation Effects Produced by a Ciprofol Initial Infusion or Bolus Dose Followed by Continuous Maintenance Infusion in Healthy Subjects: A Phase 1 Trial

Introduction

The effects of continuous infusions of ciprofol on its pharmacodynamic and pharmacokinetic properties and safety profiles in healthy Chinese subjects were evaluated.

Methods

In this open-label, randomized, two-way cross-over study, subjects received initial doses of continuous ciprofol/propofol as an infusion for 30 min in part 1 (n = 8) and a bolus dose in part 2 (n = 8) followed by maintenance infusions for a total of 4 h in part 1 and 12 h in part 2. Each subject participated in both parts with a washout time of at least 40 h.

Results

The safety and tolerability parameters of ciprofol were similar to those of propofol, and all treatment-emergent adverse events were mild. The incidences of injection pain and respiratory depression in subjects given ciprofol were lower than those receiving propofol. The pharmacokinetic parameters C_max, t_max, t_1/2, λz and MRT for ciprofol and propofol were similar, while CL, V_d and V_ss were statistically significantly different. Pharmacodynamic parameters including the Richmond Agitation Sedation Scale and bispectral index profiles of ciprofol were similar to those of propofol.

Conclusion

Ciprofol has potential for clinical application for continuous intravenous infusion to maintain sedation for 12 h with the same safety, tolerability and efficacy as propofol.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01914-4.

Smart Portable Pen for Continuous Monitoring of Anaesthetics in Human Serum With Machine Learning

Continuous monitoring of anaesthetics infusion is demanded by anaesthesiologists to help in defining personalized dose, hence reducing risks and side effects. We propose the first piece of technology tailored explicitly to close the loop between anaesthesiologist and patient with continuous drug monitoring. Direct detection of drugs is achieved with electrochemical techniques, and several options are present in literature to measure propofol (widely used anaesthetics). Still, the sensors proposed do not enable in-situ detection, they do not provide this information continuously, and they are based on bulky and costly lab equipment. In this paper, we present a novel smart pen-shaped electronic system for continuous monitoring of propofol in human serum. The system consists of a needle-shaped sensor, a quasi digital front-end, a smart machine learning data processing, in a single wireless battery-operated embedded device featuring Bluetooth Low Energy (BLE) communication. The system has been tested and characterized in real, undiluted human serum, at 37  ^°C. The device features a limit of detection of 3.8  μM, meeting the requirement of the target application, with an electronics system 59% smaller and 81% less power consuming w.r.t. the state-of-the-art, using a smart machine learning classification for data processing, which guarantees up to twenty continuous measure.

Oxidative stress under general intravenous and inhalation anaesthesia

Oxidative stress occurs when reactive oxygen species (ROS) production overwhelms cell protection by antioxidants. This review is focused on general anaesthesia-induced oxidative stress because it increases the rate of complications and delays recovery after surgery. It is important to know what effects of anaesthetics to expect in terms of oxidative stress, particularly in surgical procedures with high ROS production, because their either additive or antagonistic effect may be pivotal for the outcome of surgery. In vitro and animal studies on this topic are numerous but show large variability. There are not many human studies and what we know has been learned from different surgical procedures measuring different endpoints in blood samples taken mostly before and after surgery. In these studies most intravenous anaesthetics have antioxidative properties, while volatile anaesthetics temporarily increase oxidative stress in longer surgical procedures.

Endoscopist-Directed Propofol as an Adjunct to Standard Sedation: A Canadian Experience

Background

Sedation practices vary widely by region. In Canada, endoscopist-directed administration of a combination of fentanyl and midazolam is standard practice. A minority of cases are performed with propofol.

Aims

To describe the safety of nonanaesthetist administered low-dose propofol as an adjunct to standard sedation.

Methods

This was a single-centre retrospective study of patients having undergone endoscopic procedures with propofol sedation between 2004 and 2012 in a teaching hospital in Montreal. Procedures were performed by gastroenterologists trained in Advanced Cardiovascular Life Support. Sedation was administered by intravenous bolus by a registered nurse, under the direction of the endoscopist. Outcomes of procedures were collected in the context of a retrospective chart review using the hospital's endoscopy database.

Results

Of patients undergoing endoscopies at our centre, 4930 patients received propofol as an adjunct to standard sedation with fentanyl and midazolam. Cecal intubation rate for colonoscopies (n = 2921) was 92.0%. Gastroscopies (n = 1614), flexible sigmoidoscopies (n = 28), endoscopic retrograde cholangiopancreatography (n = 331) and percutaneous endoscopic gastrostomy insertion (n = 36) had success rates, defined as successful completion of the procedure within anatomical limits, of 99.0, 96.4, 94.0 and 91.7%, respectively. The average dose of propofol used for each procedure was 34.5 ± 20.8 mg. Fentanyl was used in 67.4% of procedures at an average dose of 94.3 ± 17.5 mcg. Midazolam was used in 92.7% of cases at an average dose of 3.0 ± 0.7 mg. Reversal agents (naloxone or flumazenil) were used in 0.43% of the cases (n = 21). Patients who received propofol were discharged uneventfully within the usual postprocedure recovery time. One patient required sedation-related hospitalization. For patients having received propofol in addition to standard sedation agents, 99.6% experienced no adverse events. There were no mortalities.

Conclusion

The use of low-dose propofol as an adjunct to fentanyl and midazolam, administered by a registered nurse under the direction of the endoscopist was safe and effective in patients at our centre.

Transcranial magnetic stimulation tracks subminute changes in cortical excitability during propofol anesthesia

Automated anesthesia systems that continuously monitor cortical excitability (CE) changes to govern drug infusion rates, are desirable. Paired‐pulse transcranial magnetic stimulation (ppTMS), with electromyography (EMG), provides noninvasive CE measures. We tested whether, and with what temporal resolution, ppTMS‐EMG detects dose‐dependent CE in rats anesthetized with continuous intravenous propofol. Motor‐evoked potentials (MEPs) were recorded every 20 seconds as either propofol bolus or change in infusion rate was applied. ppTMS‐derived measures varied in direct proportion to propofol dose with subminute temporal resolution. We conclude that ppTMS‐EMG enables real‐time markers of target engagement by anesthetics that may be incorporated into an automated device.

Propofol Attenuates Hypoxia/Reoxygenation-Induced Apoptosis and Autophagy in HK-2 Cells by Inhibiting JNK Activation

PURPOSE

The aim of this study was to investigate whether propofol could attenuate hypoxia/reoxygenation-induced apoptosis and autophagy in human renal proximal tubular cells (HK-2) by inhibiting JNK activation.

MATERIALS AND METHODS

HK-2 cells were treated with or without propofol or JNK inhibitor SP600125 for 1 hour and then subjected to 15 hours of hypoxia and 2 hours of reoxygenation (H/R). Cell viability and LDH release were measured with commercial kits. Cell apoptosis was evaluated by flow cytometry. The expressions of p-JNK, cleaved-caspase-3, Bcl-2, and autophagy markers LC3 and p62 were measured by Western blot or immunofluorescence.

RESULTS

HK-2 cells exposed to H/R insult showed higher cell injury (detected by increased LDH release and decreased cell viability), increased cell apoptosis index and expression of cleaved-caspase-3, a decrease in the expression of Bcl-2 accompanied by increased expression of p-JNK and LC3II, and a decrease in expression of p62. All of these alterations were attenuated by propofol treatment. Similar effects were provoked upon treatment with the JNK inhibitor SP600125. Moreover, the protective effects were more obvious with the combination of propofol and SP600125.

CONCLUSION

These results suggest that propofol could attenuate hypoxia/reoxygenation induced apoptosis and autophagy in HK-2 cells, probably through inhibiting JNK activation.

Propofol pump controls nonconvulsive status epilepticus in a hepatic encephalopathy patient: A case report

BACKGROUND

Status epilepticus is an emergent and critical condition which needs management without hesitation. Nonconvulsive status epilepticus (NCSE) tends to be less recognized, and its diagnosis is delayed in comparison with overt status epilepticus because of the absence of specific clinical signs. It is often difficult to make a diagnosis, particularly in patients with hepatic encephalopathy.

CASE SUMMARY

A 38-year-old man with a history of alcoholic liver cirrhosis presented with altered mental status; the initial diagnosis was hepatic encephalopathy. Although optimal treatment for hepatic encephalopathy was administered, the patient's mental status did not improve. A final diagnosis of NCSE was made by continuous electroencephalogram (EEG) monitoring. Treatment with levetiracetam and propofol pump was immediately started. The patient’s consciousness gradually improved after discontinuation of propofol therapy, and no further epileptic discharge was observed by EEG monitoring. After 1 wk, the patient returned to full consciousness, and he was able to walk in the hospital ward without assistance. He was discharged with minimal sequela of bilateral conjunctivitis.

CONCLUSION

In cases of persistent altered mental status without reasonable diagnosis, NCSE should be considered in hepatic encephalopathy patients with persistently altered levels of consciousness, and EEG monitoring is very important. We also recommend propofol as a safe and efficient therapy for NCSE in liver cirrhosis patients.

A Comparison of Safety and Efficacy of Dexmedetomidine and Propofol in Children with Autism and Autism Spectrum Disorders Undergoing Magnetic Resonance Imaging

Children with autism and autism spectrum disorders have a high incidence of neurologic comorbidities. Consequently, evaluation with magnetic resonance imaging (MRI) is deemed necessary. Sedating these patients poses several challenges. This retrospective study compared the efficacy and safety of dexmedetomidine to propofol in sedating autistic patients undergoing MRI. There were 56 patients in the dexmedetomidine group and 49 in the propofol group. All of the patients successfully completed the procedure. Recovery and discharge times were significantly lower in the propofol group, while the dexmedetomidine group maintained more stable hemodynamics. Both propofol and dexmedetomidine proved to be adequate and safe medications in the sedation of autistic children undergoing MRI.

Safety and Efficacy of a Propofol and Ketamine Based Procedural Sedation Protocol in Children with Cerebral Palsy Undergoing Botulinum Toxin A Injections

BACKGROUND

Pediatric patients with cerebral palsy often undergo intramuscular botulinum toxin (BoNT-A) injections. These injections can be painful and may require procedural sedation. An ideal sedation protocol has yet to be elucidated.

OBJECTIVE

To investigate the safety and efficacy of a propofol and ketamine based sedation protocol in pediatric patients with cerebral palsy requiring BoNT-A injections.

DESIGN

Retrospective chart review.

SETTING

The sedations took place in a procedural sedation suite at a tertiary children's hospital from February 2013 through September 2017.

PATIENTS

164 patients with diagnoses of cerebral palsy undergoing propofol and ketamine based sedation for injections with botulinum toxin A.

METHODS

An initial bolus of 0.5 mg/kg ketamine followed by a 2 mg/kg bolus of propofol was administered with supplemental boluses of propofol as needed to achieve deep sedation during the intramuscular BoNT-A injections.

MAIN OUTCOME MEASUREMENTS

Propofol dosages, adverse events, serious adverse events, and sedation time parameters were reviewed.

RESULTS

345 sedations were successfully performed on 164 patients. The median total dose of propofol was 4.7 mg/kg (interquartile range [IQR]: 3.5, 6.3). Adverse events were encountered in 10.1% of procedures including hypoxemia responsive to supplemental oxygen (9.6%) and transient apnea (1.4%). The mean procedure time, recovery time, and total sedation time were 10, 11 and 33 minutes, respectively. With regard to patient variables, including age, weight, dose of propofol, sedation time, and Gross Motor Function Classification System classification, there was no association with increased incidence of adverse events.

CONCLUSION

Our sedation protocol of propofol and ketamine is safe and effective in children with cerebral palsy undergoing procedural sedation for intramuscular injections with BoNT-A. The adverse events encountered appeared to be related to airway and respiratory complications secondary to musculoskeletal deformities, emphasizing the importance of airway monitoring and management in these patients.

LEVEL

IV.

Effect of Perioperative Lidocaine, Propofol and Steroids on Pulmonary Metastasis in a Murine Model of Breast Cancer Surgery

Addressing the hypothesis that anaesthetic-analgesic technique during cancer surgery might influence recurrence or metastatic spread is a research priority. Propofol, which has anti-inflammatory properties in vitro, is clinically associated with reduced risk of cancer recurrence compared with sevoflurane anaesthesia in retrospective studies. Amide local anaesthetics, such as lidocaine, have cancer inhibiting effects in vitro. Steroids have anti-inflammatory and immunosuppressive effects and are associated with improved recovery after major non-cancer surgery. We compared the effects of propofol, lidocaine and methylprednisolone on postoperative metastasis in a murine model of breast cancer surgery under sevoflurane anaesthesia. 4T1 tumour cells were introduced into the mammary fat-pad of female BALB/c mice and the resulting tumour resected seven days later under general anaesthesia with sevoflurane. Mice (n = 72) were randomized to four treatment groups: Sevoflurane alone (control); Propofol group received 5 mg.kg-1; Lidocaine group received 1.5 mg.kg-1 followed by 2 mg.kg-1.h-1 infusion; Methylprednisolone group received 30 mg.kg-1 methylprednisolone. The primary outcome measure was pulmonary metastasis colony count, as assessed by in-vitro proliferation, two weeks post-operatively. This was achieved by treating the post-mortem lung tissue with collagenase IV, straining and culturing for 14 days prior to colony count. Compared with control, lidocaine and propofol each individually reduced pulmonary metastasis colonies; mean (SD) 846 (±581) vs. 88 (±52) vs. 34 (±44) respectively, (p = 0.0001 and p = 0.0001). Methylprednisolone increased lung metastasis, 2555 (±609) vs. 846 (±581), p = 0.0001. Post-operative hepatic metastatic disease and serum interleukin-6 and vascular endothelial growth factor levels were similar in all groups. In conclusion, in a murine model of breast cancer surgery during sevoflurane anaesthesia, propofol and lidocaine each decreased pulmonary metastasis, while methylprednisolone increased it.

Duration of therapeutic coma and outcome of refractory status epilepticus

OBJECTIVE

Examine the association of duration of therapeutic coma (TC) with seizure recurrence, morbidity, and mortality in refractory status epilepticus (RSE). Define an optimal window for TC that provides sustained seizure control and minimizes complications.

METHODS

Retrospective, observational cohort study involving patients who presented with RSE to the University of Alabama at Birmingham or the University of California at San Francisco from 2010 to 2016. Relationship of duration of TC with primary and secondary outcomes was evaluated using two-sample t tests, simple linear regression, and chi-square tests. Multivariable linear and logistic regression models were used to identify independent predictors. Predictive ability of TC for seizure recurrence was quantified using a receiver-operating characteristic curve. Youden index was used to determine an optimal cutoff value.

RESULTS

Multivariable analysis of clinical and treatment characteristics of 182 patients who were treated predominantly with propofol as anesthetic agent showed that longer duration of the first trial of TC (27.2 vs 15.6 hours) was independently associated with a higher chance of seizure recurrence following the first weaning attempt (P = 0.038) but not with poor functional neurologic outcome upon discharge, in-hospital complications, or mortality. Furthermore, higher doses of anesthetic utilized during the first trial of TC were independently associated with fewer in-hospital complications (P = 0.003) and associated with a shorter duration of mechanical ventilation and total length of stay. Duration of TC was identified as an independent predictor of seizure recurrence with an optimal cutoff point at 35 hours.

SIGNIFICANCE

This study suggests that a shorter duration yet deeper TC as treatment for RSE may be more effective and safer than the currently recommended TC duration of 24-48 hours. Prospective and randomized trials should be conducted to validate these assertions.

Influence of propofol dose and blood components on duration of electrical seizures in electroconvulsive therapy

Background and objectives

Propofol is commonly employed as a hypnotic agent to perform electroconvulsive therapy, but it exhibits also anticonvulsant properties. The main objective was to study the effect of the weight-adjusted dose of propofol on duration of the electrical seizure. Secondary objectives were to study the effect of absolute dose of propofol on duration of electrical seizure, the effect of both absolute and weight-adjusted doses on values of bispectral index, and the influence of blood chemistry on anticonvulsant effect.

Methods

After approval of the Institutional Review Board, a retrospective chart review was performed of all patients who underwent at least one electroconvulsive therapy session. Multiple lineal regression analysis adjusted for potential confounders was employed to explore the effect of propofol dosage on values of bispectral index and on duration of seizure; bivariate correlation analyses were previously performed to identify variables fulfilling confounding criteria, specifically values of Spearman's rho >0.10. Results of regression analysis were expressed as B coefficient with its 95% confident interval.

Results

76 patients received 631 acute phase sessions. Propofol showed a statistically significant negative effect on duration of seizure (specifically a reduction of 4.081 s for every mg.kg⁻¹ of propofol; CI95%: −7906 to −0.255, p = 0.037) but not on bispectral index values. Slight anemia and hypoalbuminemia were very infrequent conditions, and the anticonvulsant effect was not influenced by these parameters.

Conclusions

Propofol weight-adjusted dose is negatively related to duration of seizures. It should be carefully titrated when employed to perform electroconvulsive therapy.

Propofol is a more effective and safer sedative agent than midazolam in endoscopic injection sclerotherapy for esophageal varices in patients with liver cirrhosis: a randomized controlled trial

OBJECTIVE

The efficacy of sedation during endoscopic injection sclerotherapy (EIS) for esophageal varices (EVs) in patients with liver cirrhosis remains unclear. The aim of this study is to compare the efficacy and safety between propofol- and midazolam-based sedation for EIS.

METHODS

Twenty-three patients with EVs were prospectively and randomly assigned to midazolam-based (Midazolam group) or propofol-based (Propofol group) sedation. All patients underwent a number connection test (NCT) to evaluate minimal hepatic encephalopathy (MHE) on the day before and at 2 and 24 hours following EIS. The primary endpoint was exacerbation of MHE after EIS, which was defined as deterioration of the NCT. The secondary endpoints were postoperative awareness, technical success rate, frequency of body movement, patient and operator satisfaction, cardiorespiratory dynamics during EIS, and adverse events.

RESULTS

Exacerbations of MHE at 2 hours after EIS compared with those before EIS were not significantly different between the two groups. In both groups, the deterioration of NCT scores before and 2 hours after EIS was observed (Propofol group: 60.0 vs. 70.0 s, P = 0.026; Midazolam group: 42.5 vs. 67.0 s, P = 0.002). There were no significant differences in awareness, technical success rate, or patient satisfaction. However, the frequency of body movement in the Propofol group was significantly lower than that in the Midazolam group (1 vs. 4, P = 0.045), and operator satisfaction in the Propofol group was significantly higher than that in the Midazolam group (P = 0.016). No adverse events were observed.

CONCLUSIONS

Propofol-based sedation exacerbated MHE after EIS similarly to midazolam-based sedation in patients with liver cirrhosis. However, propofol-based sedation provided stable sedation with a lower frequency of body movements and high operator satisfaction.

Pharmacokinetic Analysis of Propofol Target-Controlled Infusion Models in Chinese Patients with Hepatic Insufficiency

Background

Effects of liver dysfunction on target-controlled infusion (TCI) with Marsh parameters of propofol remain poorly documented. The purpose of this study was to evaluate the performance of propofol TCI in a cohort of Chinese patients with severe hepatic insufficiency.

Material/Methods

We assigned 32 patients who underwent liver transplantation to 3 groups according to Child-Turcotte-Pugh (CTP) score. Anesthesia, preceding liver transplantation, was induced and maintained with TCI of 3 μg/mL propofol. Plasma propofol concentration was assessed. Propofol TCI system performance was analyzed in terms of error size, bias, and divergence. Data on plasma propofol concentrations were analyzed, and population pharmacokinetic parameters of propofol were fitted by NONMEM software.

Results

In the CTP C group, measured concentrations of propofol were much higher than those of predictive concentrations, with significantly higher overshoots compared to CTP A patients. Overall, TCI system performance was significantly lower in CTP C patients. Linear regression equations of Cm vs. Cp and a regression model of pharmacokinetics were obtained.

Conclusions

Propofol TCI device performance with Marsh parameters was clinically acceptable in CTP A patients but may not be suitable for patients with severe hepatic impairment.

[Influence of propofol dose and blood components on duration of electrical seizures in electroconvulsive therapy]

BACKGROUND AND OBJECTIVES

Propofol is commonly employed as a hypnotic agent to perform electroconvulsive therapy, but it exhibits also anticonvulsant properties. The main objective was to study the effect of the weight-adjusted dose of propofol on duration of the electrical seizure. Secondary objectives were to study the effect of absolute dose of propofol on duration of electrical seizure, the effect of both absolute and weight-adjusted doses on values of bispectral index, and the influence of blood chemistry on anticonvulsant effect.

METHODS

After approval of the Institutional Review Board, a retrospective chart review was performed of all patients who underwent at least one electroconvulsive therapy session. Multiple lineal regression analysis adjusted for potential confounders was employed to explore the effect of propofol dosage on values of bispectral index and on duration of seizure; bivariate correlation analyses were previously performed to identify variables fulfilling confounding criteria, specifically values of Spearman's rho >0.10. Results of regression analysis were expressed as B coefficient with its 95% confident interval.

RESULTS

76 patients received 631 acute phase sessions. Propofol showed a statistically significant negative effect on duration of seizure (specifically a reduction of 4.081s for every mg.kg^-1 of propofol; CI95%: -7906 to -0.255, p=0.037) but not on bispectral index values. Slight anemia and hypoalbuminemia were very infrequent conditions, and the anticonvulsant effect was not influenced by these parameters.

CONCLUSIONS

Propofol weight-adjusted dose is negatively related to duration of seizures. It should be carefully titrated when employed to perform electroconvulsive therapy.

Sedation with Propofol for Bronchoscopy in Cystic Fibrosis Lung Transplant Recipients

INTRODUCTION

Flexible fiberoptic bronchoscopy (FFB) plays an important role in the surveillance of cystic fibrosis (CF) patients after lung transplantation (LTx). With rapid onset and clearance, propofol provides a safe and efficient method for sedation during FFB, yet sedation requirements for CF patients are not well described.

OBJECTIVES

Due to pharmacokinetic differences for other classes of drugs in CF patients, this study was performed to examine propofol requirements for sedation during bronchoscopy in lung transplant recipients with CF.

METHODS

A single-center retrospective cohort study was performed to examine propofol sedation requirements during outpatient surveillance. FFB procedures with transbronchial biopsy (TBB) in post-LTx recipients between 2009 and 2014 were conducted.

RESULTS

A total of 40 FFB procedures with TBB were performed 20 CF (11 females), 20 non-CF (11 females). Mean (± SD) age was 25.6 ± 9.2 (range 13-42) years and 22.2 ± 10.8 (range 11-39) years for the CF and non-CF groups, respectively. Propofol requirements were significantly higher in the CF patients compared to the non-CF patients. Mean (± SD) propofol dose for CF patients was 334 ± 86 versus 214 ± 88 mg for non-CF patients (p < 0.001). Mean (± SD) propofol dose per weight (mg/kg) was 6.5 ± 2.1 for CF patients versus 3.8 ± 1.6 for non-CF patients (p < 0.001).

CONCLUSIONS

Compared to a non-CF cohort, CF lung transplant recipients required higher dosages of propofol for sedation during FFB with TBB.

Efficacy and safety of sedation during endoscopic submucosal dissection of gastric cancers using a comparative trial of propofol versus midazolam

BACKGROUND AND STUDY AIMS

Proper sedation is necessary for the safe and satisfactory completion of endoscopic submucosal dissection (ESD) for early gastric cancer. This study was conducted as a comparative trial of efficacy and safety, comparing propofol-based sedation and midazolam-based sedation during ESD of early gastric cancer patients.

PATIENTS AND METHODS

This study examined 64 lesions in 58 patients treated using ESD with midazolam plus pentazocine between July 2013 and January 2014 (group M) and 237 lesions in 216 patients treated by ESD using propofol plus pentazocine between February 2014 and December 2015 (group P). The two groups were compared in terms of the frequency of body movement during ESD as the primary outcome and in terms of the procedure time, en bloc resection rate, intraoperative change in cardiorespiratory dynamics, and postoperative awareness as the secondary outcomes. Body movement was defined as movement by a patient that required interruption of the procedure or restraint of the patient's body trunk, and addition of a sedative agent.

RESULTS

The median frequency of body movement during ESD was significantly lower in group P (0 times) than in group M (3 times) ( P  < 0.001). No significant difference was found for the mean procedure time (117 min in group P; 127 min in group M). Although no significant difference was found in the incidence of hypoxemia, bradycardia, or bradypnea, the incidence of hypotension was significantly higher in group P (31.5 %) than in group M (6.9 %) ( P  = 0.004). Patients in group P had significantly higher postoperative awareness immediately after ESD and at 1 hour after ESD ( P  = 0.002 and 0.022, respectively).

CONCLUSION

These results demonstrate the efficacy and safety of propofol-based sedation for gastric ESD.

Propofol Sedation Exacerbates Kidney Pathology and Dissemination of Bacteria during Staphylococcus aureus Bloodstream Infections

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for large numbers of postsurgical nosocomial infections across the United States and worldwide. Propofol anesthesia is widely used in surgery and in intensive care units, and recent evidence indicates that even brief exposure to propofol can substantially increase host susceptibility to microbial infection. Here, we delineate the impact of propofol sedation on MRSA bloodstream infections in mice in the presence and absence of prophylactic antibiotic treatment. Consistent with previous reports, brief periods of anesthesia with propofol were sufficient to significantly increase bacterial burdens and kidney pathology in mice infected with MRSA. Propofol exposure increased neutrophilic infiltrates into the kidney and enhanced bacterial dissemination throughout kidney tissue. Propofol sedation reduced populations of effector phagocytes and mature dendritic cells within the kidney and led to the apparent expansion of myeloid-derived suppressor cell-like populations. When propofol was coadministered with vancomycin prophylaxis, it dramatically increased kidney abscess formation and bacterial dissemination throughout kidney tissue at early times post-S. aureus infection compared to antibiotic-treated but nonsedated animals. Taken together, our data indicate that short-term sedation with propofol significantly increases the severity of bloodstream MRSA infection, even when administered in conjunction with vancomycin prophylaxis.

Noninvasive Targeted Transcranial Neuromodulation via Focused Ultrasound Gated Drug Release from Nanoemulsions

Targeted, noninvasive neuromodulation of the brain of an otherwise awake subject could revolutionize both basic and clinical neuroscience. Toward this goal, we have developed nanoparticles that allow noninvasive uncaging of a neuromodulatory drug, in this case the small molecule anesthetic propofol, upon the application of focused ultrasound. These nanoparticles are composed of biodegradable and biocompatible constituents and are activated using sonication parameters that are readily achievable by current clinical transcranial focused ultrasound systems. These particles are potent enough that their activation can silence seizures in an acute rat seizure model. Notably, there is no evidence of brain parenchymal damage or blood-brain barrier opening with their use. Further development of these particles promises noninvasive, focal, and image-guided clinical neuromodulation along a variety of pharmacological axes.

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.

Endoscopic Approaches to the Treatment of Variceal Hemorrhage in Hemodialysis-Dependent Patients

Background. Esophagogastric variceal hemorrhage leads to challenging situation in chronic kidney disease patients on maintenance hemodialysis. Aims. To determine the safety and efficacy of endoscopic approaches to patients with hemodialysis-dependent concomitant with esophagogastric varices. Methods. Medical records were reviewed from January 1, 2004, to December 31, 2015, in our hospital. Five consecutive hemodialysis-dependent patients with variceal hemorrhage who underwent endoscopic treatments were retrospectively studied. Results. The median age of the patients was 54 years (range 34–67 years) and the median follow-up period was 21.3 months (range 7–134 months). All the patients received a total of three times heparin-free hemodialysis 24 hours before and no more than 24 hours and 72 hours after endoscopic treatment. They successfully had endoscopic variceal ligation, endoscopic injection sclerotherapy, and/or N-butyl cyanoacrylate injection. The short-term efficacy is satisfying and long-term follow-up showed episodes of rebleeding. Conclusions. Endoscopic approaches are the alternative options in the treatment of upper gastroenterology variceal hemorrhage in hemodialysis-dependent patients without severe complications.

Clinico-anesthetic changes following administration of propofol alone and in combination of meperidine and pentazocine lactate in dogs

Aim:

The aim of this study is to find out the effect of propofol and its combination with meperidine and pentazocine lactate on certain clinico-anesthetic profiles in dogs.

Materials and Methods:

15 apparently healthy mongrel dogs of either sex of about 1 year of age were randomly divided into three groups of five dogs each. The animals of Group I were administered propofol intravenously alone “to effect,” whereas meperidine at 2 mg/kgb.wt. and pentazocine lactate at 2 mg/kg b.wt. were injected intramuscularly 15 min before propofol “to effect” in Groups II and III, respectively. Atropine sulfate at 0.04 mg/kgb.wt. was injected intramuscularly 20 min before each treatment. Rectal temperature, heart rate, respiration rate, and anesthetic indices were recorded before and at 5, 10, 20, 30, and 60 min of induction.

Results:

As compared to Group I, the animals of Groups II and III exhibited a significant decrease (p<0.05) in the level of rectal temperature, respiration rate, and heart rate. Duration of recumbency, time of standing, time of recovery as well as the duration of analgesia were longer in pentazocine lactate (Group III) followed by meperidine (Group II) as compared to propofol alone (Group I). Meperidine treated dogs showed defecation and muscle twitching during anesthesia.

Conclusion:

Meperidine and pentazocine are suitable opioids used in combination with propofol for achieving surgical anesthesia and helpful in reduction of propofol dose.

Propofol in the treatment of refractory migraine headaches

INTRODUCTION

Refractory/intractable migraine headaches are associated with chronic pain that does not respond to standard care of treatment. Propofol(2,6-diisopropylphenol) in sub-anesthetic doses has been reported to be beneficial in such patients. The present article describes the complete drug profile of propofol in the management of these super-refractory migraine headaches.

AREAS COVERED

The article covers different preclinical and clinical studies available in the literature. Expert commentary: Propofol is useful as an off-label drug molecule in an emergency situation of refractory migraines where it has been found to reduce the pain intensity. The molecule with a narrow therapeutic index and high abuse potential is prescribed only when conventional drugs fail to deliver any relief. There are not adequate double-blind crossover studies that substantiate the effectiveness of propofol in the treatment of migraine headaches. Furthermore, long-term outcomes for the use of propofol in migraine headaches requires an extensive investigation.

Sleep Homeostasis and General Anesthesia: Are Fruit Flies Well Rested after Emergence from Propofol?

BACKGROUND

Shared neurophysiologic features between sleep and anesthetic-induced hypnosis indicate a potential overlap in neuronal circuitry underlying both states. Previous studies in rodents indicate that preexisting sleep debt discharges under propofol anesthesia. The authors explored the hypothesis that propofol anesthesia also dispels sleep pressure in the fruit fly. To the authors' knowledge, this constitutes the first time propofol has been tested in the genetically tractable model, Drosophila melanogaster.

METHODS

Daily sleep was measured in Drosophila by using a standard locomotor activity assay. Propofol was administered by transferring flies onto food containing various doses of propofol or equivalent concentrations of vehicle. High-performance liquid chromatography was used to measure the tissue concentrations of ingested propofol. To determine whether propofol anesthesia substitutes for natural sleep, the flies were subjected to 10-h sleep deprivation (SD), followed by 6-h propofol exposure, and monitored for subsequent sleep.

RESULTS

Oral propofol treatment causes anesthesia in flies as indicated by a dose-dependent reduction in locomotor activity (n = 11 to 41 flies from each group) and increased arousal threshold (n = 79 to 137). Recovery sleep in flies fed propofol after SD was delayed until after flies had emerged from anesthesia (n = 30 to 48). SD was also associated with a significant increase in mortality in propofol-fed flies (n = 44 to 46).

CONCLUSIONS

Together, these data indicate that fruit flies are effectively anesthetized by ingestion of propofol and suggest that homologous molecular and neuronal targets of propofol are conserved in Drosophila. However, behavioral measurements indicate that propofol anesthesia does not satisfy the homeostatic need for sleep and may compromise the restorative properties of sleep.

Comparison of Intravenous Anesthetic Agents for the Treatment of Refractory Status Epilepticus

Status epilepticus that cannot be controlled with first- and second-line agents is called refractory status epilepticus (RSE), a condition that is associated with significant morbidity and mortality. Most experts agree that treatment of RSE necessitates the use of continuous infusion intravenous anesthetic drugs such as midazolam, propofol, pentobarbital, thiopental, and ketamine, each of which has its own unique characteristics. This review compares the various anesthetic agents while providing an approach to their use in adult patients, along with possible associated complications.

Determination of the appropriate propofol infusion rate for outpatient upper gastrointestinal endoscopy-a randomized prospective study

Background

Pain and discomfort related to endoscopy sessions can be alleviated by sedation, which minimizes anxiety and allows safe examination. For outpatient endoscopy, reliable short-term sedation without secondary effects is required. This study aimed to assess the effects of intravenous propofol rates on sedation in outpatients undergoing upper gastrointestinal endoscopy.

Methods

This randomized prospective study evaluated 300 outpatients submitted to upper gastrointestinal endoscopy. Patients received propofol at 500, 1000 or 2000 ml/h. The primary outcome assessed was hypoxemia incidence. In addition, time to sedation and incidence of hypotension, deep sedation, extremity motor activity, cough, nausea, hiccough, and awareness were evaluated.

Results

Recovery time and incidence of hypoxemia, hypotension, and deep sedation were significantly increased in individuals treated at 2000 ml/h in comparison with values obtained for 500 and 1000 ml/h groups (P < 0.01). Compared with the 500 ml/h group, motor activity of the extremities, cough, nausea, hiccough, and awareness were significantly decreased and the mean scores for endoscopist’s and patients’ satisfaction were significantly increased in the 1000 and 2000 ml/h groups (P < 0.01).

Conclusion

Propofol infused at 1000 ml/h appeared to be the most suitable infusion rate for outpatient upper gastrointestinal endoscopy.

Trial registration

Registration number: ChiCTR-TRC-14004786; Registration date: 2014-06-04

Subthalamic local field potentials in Parkinson's disease and isolated dystonia: An evaluation of potential biomarkers

Local field potentials (LFP) recorded from the subthalamic nucleus in patients with Parkinson's disease (PD) demonstrate prominent oscillations in the beta (13-30 Hz) frequency range, and reduction of beta band spectral power by levodopa and deep brain stimulation (DBS) is correlated with motor symptom improvement. Several features of beta activity have been theorized to be specific biomarkers of the parkinsonian state, though these have rarely been studied in non-parkinsonian conditions. To compare resting state LFP features in PD and isolated dystonia and evaluate disease-specific biomarkers, we recorded subthalamic LFPs from 28 akinetic-rigid PD and 12 isolated dystonia patients during awake DBS implantation. Spectral power and phase-amplitude coupling characteristics were analyzed. In 26/28 PD and 11/12 isolated dystonia patients, the LFP power spectrum had a peak in the beta frequency range, with similar amplitudes between groups. Resting state power did not differ between groups in the theta (5-8 Hz), alpha (8-12 Hz), beta (13-30 Hz), broadband gamma (50-200 Hz), or high frequency oscillation (HFO, 250-350 Hz) bands. Analysis of phase-amplitude coupling between low frequency phase and HFO amplitude revealed significant interactions in 19/28 PD and 6/12 dystonia recordings without significant differences in maximal coupling or preferred phase. Two features of subthalamic LFPs that have been proposed as specific parkinsonian biomarkers, beta power and coupling of beta phase to HFO amplitude, were also present in isolated dystonia, including focal dystonias. This casts doubt on the utility of these metrics as disease-specific diagnostic biomarkers.

Propofol Pharmacokinetics and Estimation of Fetal Propofol Exposure during Mid-Gestational Fetal Surgery: A Maternal-Fetal Sheep Model

BACKGROUND

Measuring fetal drug concentrations is extremely difficult in humans. We conducted a study in pregnant sheep to simultaneously describe maternal and fetal concentrations of propofol, a common intravenous anesthetic agent used in humans. Compared to inhalational anesthesia, propofol supplemented anesthesia lowered the dose of desflurane required to provide adequate uterine relaxation during open fetal surgery. This resulted in better intraoperative fetal cardiac outcome. This study describes maternal and fetal propofol pharmacokinetics (PK) using a chronically instrumented maternal-fetal sheep model.

METHODS

Fetal and maternal blood samples were simultaneously collected from eight mid-gestational pregnant ewes during general anesthesia with propofol, remifentanil and desflurane. Nonlinear mixed-effects modeling was performed by using NONMEM software. Total body weight, gestational age and hemodynamic parameters were tested in the covariate analysis. The final model was validated by bootstrapping and visual predictive check.

RESULTS

A total of 160 propofol samples were collected. A 2-compartment maternal PK model with a third fetal compartment appropriately described the data. Mean population parameter estimates for maternal propofol clearance and central volume of distribution were 4.17 L/min and 37.7 L, respectively, in a typical ewe with a median heart rate of 135 beats/min. Increase in maternal heart rate significantly correlated with increase in propofol clearance. The estimated population maternal-fetal inter-compartment clearance was 0.0138 L/min and the volume of distribution of propofol in the fetus was 0.144 L. Fetal propofol clearance was found to be almost negligible compared to maternal clearance and could not be robustly estimated.

CONCLUSIONS

For the first time, a maternal-fetal PK model of propofol in pregnant ewes was successfully developed. This study narrows the gap in our knowledge in maternal-fetal PK model in human. Our study confirms that maternal heart rate has an important influence on the pharmacokinetics of propofol during pregnancy. Much lower propofol concentration in the fetus compared to maternal concentrations explain limited placental transfer in in-vivo paired model, and less direct fetal cardiac depression we observed earlier with propofol supplemented inhalational anesthesia compared to higher dose inhalational anesthesia in humans and sheep.

Impaired postural stability after laparoscopic surgery

BACKGROUND

Early postoperative mobilisation may reduce patient morbidity and improve hospital efficiency by accelerated discharge. The aim of this study was to measure postural stability early after laparoscopic surgery in order to assess how early it is safe to mobilise and discharge patients.

METHODS

We included 25 women undergoing outpatient gynaecological laparoscopic surgery in the study. Patients received standardised anaesthesia with propofol, remifentanil and rocuronium. Postural stability was assessed preoperatively, at 30 min after tracheal extubation, and at discharge from the post-anaesthesia care unit using a force platform where sway area, mean sway and sway velocity were determined. The assessments were done with eyes closed and with eyes open. The primary outcome was the change in sway area with eyes closed 30 min after extubation. Data are reported as median (25-75% range).

RESULTS

Three patients could not perform all the test's 30 min after extubation. Thirty minutes after extubation, sway area with eyes closed had increased significantly with 84 mm(2) (9-172, P = 0.011) and 108 mm(2) with eyes open (25-295, P = 0.0017). Median mean sway had also increased significantly 30 min postoperatively. No significant changes were found for sway velocity. We found no significant changes in mean sway, sway area or sway velocity at discharge from the post-anaesthesia care unit approximately 2 h after surgery.

CONCLUSION

Postural stability was significantly impaired 30 min after outpatient gynaecological laparoscopic surgery. However, the postural stability was normalised at discharge from the post-anaesthesia care unit 2 h after surgery.

Dexmedetomidine increases tau phosphorylation under normothermic conditions in vivo and in vitro

There is developing interest in the potential association between anesthesia and the onset and progression of Alzheimer's disease. Several anesthetics have, thus, been demonstrated to induce tau hyperphosphorylation, an effect mostly mediated by anesthesia-induced hypothermia. Here, we tested the hypothesis that acute normothermic administration of dexmedetomidine (Dex), an intravenous sedative used in intensive care units, would result in tau hyperphosphorylation in vivo and in vitro. When administered to nontransgenic mice, Dex-induced tau hyperphosphorylation persisting up to 6 hours in the hippocampus for the AT8 epitope. Pretreatment with atipamezole, a highly specific α2-adrenergic receptor antagonist, blocked Dex-induced tau hyperphosphorylation. Furthermore, Dex dose-dependently increased tau phosphorylation at AT8 in SH-SY5Y cells, impaired mice spatial memory in the Barnes maze and promoted tau hyperphosphorylation and aggregation in transgenic hTau mice. These findings suggest that Dex: (1) increases tau phosphorylation, in vivo and in vitro, in the absence of anesthetic-induced hypothermia and through α2-adrenergic receptor activation, (2) promotes tau aggregation in a mouse model of tauopathy, and (3) impacts spatial reference memory.

Ligand binding to the FA3-FA4 cleft inhibits the esterase-like activity of human serum albumin

The hydrolysis of 4-nitrophenyl esters of hexanoate (NphOHe) and decanoate (NphODe) by human serum albumin (HSA) at Tyr411, located at the FA3-FA4 site, has been investigated between pH 5.8 and 9.5, at 22.0°C. Values of Ks, k+2, and k+2/Ks obtained at [HSA] ≥ 5×[NphOXx] and [NphOXx] ≥ 5×[HSA] (Xx is NphOHe or NphODe) match very well each other; moreover, the deacylation step turns out to be the rate limiting step in catalysis (i.e., k+3 << k+2). The pH dependence of the kinetic parameters for the hydrolysis of NphOHe and NphODe can be described by the acidic pKa-shift of a single amino acid residue, which varies from 8.9 in the free HSA to 7.6 and 7.0 in the HSA:NphOHe and HSA:NphODe complex, respectively; the pK>a-shift appears to be correlated to the length of the fatty acid tail of the substrate. The inhibition of the HSA-Tyr411-catalyzed hydrolysis of NphOHe, NphODe, and 4-nitrophenyl myristate (NphOMy) by five inhibitors (i.e., diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol) has been investigated at pH 7.5 and 22.0°C, resulting competitive. The affinity of diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol for HSA reflects the selectivity of the FA3-FA4 cleft. Under conditions where Tyr411 is not acylated, the molar fraction of diazepam, diflunisal, ibuprofen, and 3-indoxyl-sulfate bound to HSA is higher than 0.9 whereas the molar fraction of propofol bound to HSA is ca. 0.5.

Comparison of the effect of inhaled anaesthetic with intravenous anaesthetic on pulmonary vascular resistance measurement during cardiac catheterisation

BACKGROUND

Children with pulmonary hypertension routinely undergo pulmonary vascular resistance studies to assess the disease severity and vasodilator responsiveness. It is vital that results are accurate and reliable and are not influenced by the choice of anaesthetic agent. However, there are anecdotal data to suggest that propofol and inhalational agents have different effects on pulmonary vascular resistance.

METHODS

A total of 10 children with pulmonary hypertension were selected sequentially to be included in the study. To avoid confounding because of baseline anatomic or demographic details, a crossover protocol was implemented, using propofol or isoflurane, with time for washout in between each agent and blinding of the interventionalist.

RESULTS

Pulmonary and systemic vascular resistance were not significantly different when using propofol or isoflurane. However, the calculated resistance fraction - ratio of pulmonary resistance to systemic resistance - was significantly lower when using propofol than when using isoflurane.

CONCLUSIONS

Although no difference in pulmonary vascular resistance was demonstrated, this pilot study suggests that the choice of anaesthetic agent may affect the calculation of relative pulmonary and systemic vascular resistance, and provides some preliminary evidence to favour propofol over isoflurane. These findings require replication in a larger study, and thus they should be considered in future calculations to make informed decisions about the management of children with pulmonary hypertension.

Near-infrared spectroscopy-based microcirculatory assessment in acute atrial fibrillation

Near-infrared spectroscopy is a means of assessing microcirculatory function, but has not been studied in atrial fibrillation (AF). We evaluated the effect of acute AF on thenar eminence near-infrared spectroscopy-derived microcirculatory variables. Stable patients presenting to the emergency department with acute onset AF underwent dynamic near-infrared spectroscopy assessment with a three minute vascular occlusion test (VOT). This was repeated after cardioversion to sinus rhythm (SR). Each assessment included baseline tissue oxygen saturation (StO2), slope of StO2 decrease during VOT, slope of StO2 increase post VOT, minimum and maximum StO2, amplitude of StO2 response and post-ischaemic hyperperfusion. Pre and post cardioversion values were compared by Wilcoxon signed-rank test. Twelve participants (seven male, five female) with a median age of 63 years (interquartile range 52 to 70 years) were enrolled. Median baseline StO2 was 74% before and 77% after cardioversion (P=0.03). The median slope of StO2 decrease during VOT was -0.19%/second and -0.16%/second (P=0.018) and the median slope of StO2 increase post VOT was 3.03%/second and 2.56%/second (P=0.002), pre and post cardioversion, respectively. Minimum StO2 was lower (39% versus 52%, P=0.002) and the amplitude of StO2 response greater (49% versus 40%, P=0.005) in AF, but there was no significant difference in maximum StO2 or the degree of reperfusion hyperaemia. In summary, baseline and minimum StO2 were lower with a greater ischaemic decrease in StO2 during AF, reflecting reduced tissue perfusion, compared with sinus rhythm. Recovery after ischaemia was higher in AF, suggesting normalisation of capillary recruitment during ischaemia.