Tolerance to propofol generally does not develop in pediatric patients undergoing radiation therapy

Immediate effects of propofol on mood: a randomized comparison of two doses in a cohort with depression

RATIONALE

The intravenous anesthetic propofol is known to induce positive mood effects during routine clinical use, suggesting it might be repurposed as an antidepressant, but also raising concerns about abuse potential. How propofol's acute effects vary by dose and with repeated infusions is unknown.

OBJECTIVES

This exploratory analysis aimed to (1) compare the immediate mood effects of propofol administered at two different doses, (2) describe how those mood effects change with repeated infusions, and (3) evaluate whether acute mood improvement predicts later antidepressant response.

METHODS

Twenty-four adults with moderate-to-severe treatment-resistant depression were randomized into two dosing groups. Six low- or high-dose propofol infusions were administered under blinded conditions over a two-week period. Self-reported mood states were recorded before and after each infusion using the Positive and Negative Affect Schedule (PANAS-X). Abuse potential was evaluated with the Drug Effects Questionnaire (DEQ-5).

RESULTS

At the first infusion, propofol induced acute improvements in PANAS-X Sadness, Fear, Joviality, and Serenity scales (p < 0.002), independent of dose. Over the series of six infusions, acute changes in Sadness, Fear, and Joviality, but not Serenity, diminished with infusion number (p < 0.002). The DEQ-5 "want more" rating decreased across infusions (p = 0.002). Changes in PANAS-X scales with the first infusion did not predict later improvement in depression severity (p > 0.05).

CONCLUSION

Cumulative changes in mood states observed with repeated infusions suggest that propofol engages adaptive mechanisms in mood circuitry. Subjective responses with repeated infusions do not indicate increasing potential for abuse in this patient population.

Effect of Repeated Exposure to Sevoflurane on Electroencephalographic Alpha Oscillation in Pediatric Patients Undergoing Radiation Therapy: A Prospective Observational Study

BACKGROUND

Pharmacological tolerance is defined as a decrease in the effect of a drug over time, or the need to increase the dose to achieve the same effect. It has not been established whether repeated exposure to sevoflurane induces tolerance in children.

METHODS

We conducted an observational study in children younger than 6 years of age scheduled for multiple radiotherapy sessions with sevoflurane anesthesia. To evaluate the development of sevoflurane tolerance, we analyzed changes in electroencephalographic spectral power at induction, across sessions. We fitted individual and group-level linear regression models to evaluate the correlation between the outcomes and sessions. In addition, a linear mixed-effect model was used to evaluate the association between radiotherapy sessions and outcomes.

RESULTS

Eighteen children were included and the median number of radiotherapy sessions per child was 28 (interquartile range: 10 to 33). There was no correlation between induction time and radiotherapy sessions. At the group level, the linear mixed-effect model showed, in a subgroup of patients, that alpha relative power and spectral edge frequency 95 were inversely correlated with the number of anesthesia sessions. Nonetheless, this subgroup did not differ from the other subjects in terms of age, sex, or the total number of radiotherapy sessions.

CONCLUSIONS

Our results suggest that children undergoing repeated anesthesia exposure for radiotherapy do not develop tolerance to sevoflurane. However, we found that a group of patients exhibited a reduction in the alpha relative power as a function of anesthetic exposure. These results may have implications that justify further studies.

Incidence of tolerance in children undergoing repeated administration of propofol for proton radiation therapy: a retrospective study

Background

Propofol is an excellent hypnotic drug for use in repeated radiation procedures in young children. To date, tolerance to propofol generally does not develop in pediatric patients undergoing radiation therapy. However, several studies have suggested that there may be potential for development of tolerance to propofol. The aim of this study was to evaluate the development of a tolerance to propofol used for repeated deep sedation in children undergoing proton radiation therapy (PRT).

Methods

All children undergoing PRT at our institution between December 2015 and January 2018 were eligible for inclusion in this study. Sedation was induced by a bolus dose of propofol (2.0 mg.kg^− 1) followed by a continuous infusion of 250 μg.kg^− 1.min^− 1 via an infusion pump to achieve deep sedation. Sedation was maintained with the propofol infusion of 200 μg.kg^− 1.min^− 1, which was adjusted in 25 μg.kg^− 1.min^− 1 increments up or down as necessary to ensure deep sedation. The primary outcome was mean doses of propofol over time.

Results

Fifty-eight children were analyzed. The mean (SD) age was 4.5 (2.1) years. The mean (SD) number of treatment sessions was 19 (7). Fifteen patients (26%) developed tolerance to propofol. However, there were no significant differences between the children who developed tolerance and the children who did not develop tolerance in mean propofol dose and awakening time over time (p = 0.887 and P = 0.652, respectively). Age, the number of PRT, and attending anesthesiologists was not significantly associated with the incidence of tolerance to propofol.

Conclusion

Repeated prolonged deep sedation for PRT elicited multiple times over several weeks in young children using propofol did not develop tolerance in 74% of patients. Although the incidence of 26% tolerance to propofol may still be present, the increase in propofol dose was minimal. Therefore, the use of repeated propofol for children was safe.

Induction Dosage of Propofol for Repeated Sedations in Children With Hematological Disorders

Pediatric patients with hematologic malignancies require several procedural sedations by means of propofol infusion. We retrospectively analyzed the medical records of leukemic pediatric patients who had undergone procedural sedations at an Italian tertiary referral center (San Gerardo Hospital, Monza) from January 2011 to November 2013. We retrieved the following: demographics; diagnosis; chemotherapy phase; use of corticosteroids; induction dosage of propofol, fentanyl and/or ketamine; and the type of procedure. We used a multivariate linear mixed model to evaluate the factors affecting induction propofol dose. We analyzed 1459 procedures (59% lumbar punctures, 31% bone marrow aspirations) performed on 96 children (7 [4-10] y old, 24 [16-34] kg, 37% female) admitted for acute lymphoblastic leukemia (80%), lymphoma (11%), and acute myeloid leukemia (7%). The induction propofol dose increased by 0.03 mg/kg per each procedure (P<0.05), from 2.6 (2.0-3.2) to 3.5 (2.6-4.3) mg/kg at the first and the last procedure, respectively. Higher age, weight, and use of ketamine were associated to lower propofol dosage (P<0.01), while combined procedures increased propofol dosage (P<0.01). In a large cohort of leukemic pediatric patients undergoing procedural sedation, the induction dose of propofol was increased over time, regardless of weight, age, use of corticosteroids, diagnosis, and treatment phase.

Tolerance and Withdrawal Issues with Sedatives in the Intensive Care Unit

Prolonged use of sedative medications continues to be a concern for critical care practitioners, with potential adverse effects including tolerance and withdrawal. The amount of sedatives required in critically ill patients can be lessened and tolerance delayed with the use of pain and/or sedation scales to reach the desired effect. The current recommendation for prolonged sedation is to wean patients from the medications over several days to reduce the risk of drug withdrawal. It is important to identify patients at risk for iatrogenic withdrawal and create a treatment strategy.

Sedation and anesthesia options for pediatric patients in the radiation oncology suite

External beam radiation therapy (XRT) has become one of the cornerstones in the management of pediatric oncology cases. While the procedure itself is painless, the anxiety it causes may necessitate the provision of sedation or anesthesia for the patient. This review paper will briefly review the XRT procedure itself so that the anesthesia provider has an understanding of what is occurring during the simulation and treatment phases. We will then examine several currently used regimens for the provision of pediatric sedation in the XRT suite as well as a discussion of when and how general anesthesia should be performed if deemed necessary. Standards of care with respect to patient monitoring will be addressed. We will conclude with a survey of the developing field of radiation-based therapy administered outside of the XRT suite.

Clinical evaluation of repeated propofol total intravenous anesthesia in dog

This current study designed to evaluate any possible changes in required doses and other cardiopulmonary findings after repeated propofol total intravenous anesthesia (TIVA) in dog. The study was conducted in 6 healthy sheepdogs, weight between 16.5 and 28 kg. Anaesthesia induced by 8 mg kg(-1) of propofol and maintained by continuous propofol (0.3 mg/kg/min) infusion in saline solution. All dogs received three times of propofol anaesthesia with the same protocol in a cross over design. As the animals in first, second and third time of anaesthesia allocated into groups 1, 2 and 3, respectively. Heart Rate (HR), rectal temperature (Temp), blood oxygen saturation (SpO2) by pulse oximetry and non invasive arterial blood pressures were measured. Times to the first swallowing attempt, ability to lift the head and standing were measured during recovery. The apnea was recorded in all animals but no significant difference was recorded between groups under study. Calculated doses of induction were sufficient for intubation of the animals. The average doses foe maintenance of anesthesia did not show any significant difference between groups under study. There were no significant differences found between groups in any comparable parameter. Despite of longer recovery time in group three, there were no significant differences between the Groups in different recovery times. Repeated propofol anesthesia did not improve resistance and respiratory changes in this species. However, some effects on blood pressure may happen without any effect on heart rate.

Safe anesthesia for radiotherapy in pediatric oncology: St. Jude Children's Research Hospital Experience, 2004-2006

PURPOSE

To determine the incidence of anesthesia-related complications in children undergoing radiotherapy and the associated risk factors.

METHODS AND MATERIALS

We retrospectively investigated the incidence and types of anesthesia-related complications and examined their association with age, weight, oncology diagnosis, type of anesthetic (propofol vs. propofol and adjuncts), total propofol dose, anesthetic duration, type of radiotherapy procedure (simulation vs. radiotherapy) and patient position (prone vs. supine).

RESULTS

Between July 2004 and June 2006, propofol was used in 3,833 procedures (3,611 radiotherapy sessions and 222 simulations) in 177 patients. Complications occurred during 49 anesthetic sessions (1.3%). On univariate analysis, four factors were significantly associated with the risk of complications: procedure duration (p <0.001), total propofol dose (p <0.001), use of adjunct agents (vs. propofol alone; p = 0.029), and simulation (vs. radiotherapy; p = 0.014). Patient position (prone vs. supine) was not significantly associated with the frequency of complications (odds ratio, 0.71; 95% confidence interval, 0.33-1.53; p = 0.38). On multivariate analysis, the procedure duration (p <0.0001) and total propofol dose (p < or =0.03) were the most significant risk factors after adjustment for age, weight, anesthetic type, and procedure type. We found no evidence of the development of tolerance to propofol.

CONCLUSION

The rate of anesthesia-related complications was low (1.3%) in our study. The significant risk factors were procedure duration, total propofol dose, the use of adjunct agents with propofol, and simulation (vs. radiotherapy).

Evaluation of propofol for repeated prolonged deep sedation in children undergoing proton radiation therapy

BACKGROUND

The aim of this study is to evaluate the safety and sufficiency of a fixed dose rate propofol infusion for repeated prolonged deep sedation in children for proton radiation therapy (PRT).

METHODS

With ERB approval, we recorded anaesthesia monitoring data in children undergoing repeated prolonged propofol sedation for PRT. Sedation was introduced with a single bolus of i.v. midazolam 0.1 mg kg(-1) followed by repeated small boluses of propofol until sufficient depth of sedation was obtained. Sedation was maintained with fixed dose rate propofol infusion of 10 mg kg(-1) h(-1) in all patients up to the end of the radiation procedure. Patient characteristics, number and duration of sedation, propofol induction dose, necessity to alter propofol infusion rate, and heart rate, mean arterial pressure, respiratory rate were noted at the end of the radiation procedure before cessation of the propofol infusion. Data are mean (sd) or range (median) as appropriate.

RESULTS

Eighteen children aged from 1.4 to 4.2 yr (2.6 yr) had 27.6 (sd 2.0) (497 in total) radiation procedures within 44.1 (4.0) days lasting 55.7 (8.8) min. Propofol bolus dose for induction, monitoring, and positioning was 3.7 (1.0) mg kg(-1). Propofol bolus requirements were quite stable over the successive weeks of treatment and variability was larger between individuals than over time. In none of the children did propofol infusion rate need to be changed from the pre-set 10 mg kg(-1) h(-1) flow rate because of haemodynamic state, respiratory conditions or inadequate anaesthesia.

CONCLUSIONS

Repeated prolonged deep sedation over several weeks in very young children using a fixed rate propofol infusion was safe and adequate for all patients.

[Anaesthetic particularities for children with tumours]

OBJECTIVES

To present the more frequent solid tumors, that require a general anaesthesia and to describe the particularities of the anaesthetic management.

DATA SOURCES AND EXTRACTION

The PUBMED database was searched for articles (1990 - 2005) combined with references analysis of major articles on the topics.

DATA SYNTHESIS

Neoplasma is the first cause of paediatric death. In children less than 5 years of age, neuroblastoma and nephroblastoma are the more frequent of the tumour. The incidence of each pathology is low. However a general anaesthesia is required in numerous situations: bone marrow aspiration and biopsy, central venous catheter insertion, various biopsies under computed tomography, ultrasound, thoracoscopy or laparoscopy, MRI scan, surgery and body radiation. The key points of successful anaesthetic management include complete preoperative evaluation together with the oncology paediatric team. Particularly, cardiotoxicity may result from chemotherapy and hypertension is frequently associated with neuroblastoma and nephroblastoma. Mediastinal location of lymphomas induced a significant risk of cardiopulmonary complications during induction of general anaesthesia. A peak expiratory flow rate or a tracheal cross-section area less than 50% of predicted values are contraindication to general anaesthesia. Cephalic rhabdomyosarcoma may be responsible of difficult airway management. Specific guidelines are available for platelet and red cell transfusion in paediatric oncology patients. Surgical antibioprophylaxis are adapted in immunodepressed children to a potential increased risk of postoperative infectious complications, according personal previous history, microbiological ecology and body bacterial flora. Dosage of anaesthetic agents takes into account denutrition, hydroelectrolytic disturbances and hypovolemia.

Tolerance and Withdrawal Issues with Sedation

The stay in an ICU is a complex mixture of providing optimal care while keeping the patient safe. Means of reducing the anxiety associated with the ICU stay include frequent reorientation and maintenance of patient comfort with sedation supplemented by analgesia as needed. The most common agents used to provide sedation include benzodiazepines, propofol, and the newer dexmedetomidine. Others include barbiturate agents, neuroleptics, clonidine, etomidate, ketamine, and supplemental opioid analgesics for pain control. A common complication of sedation is tolerance, which can lead to withdrawal if the sedation is discontinued hastily. This article evaluates the occurrence of tolerance and withdrawal in the most commonly used sedatives in critically ill patients.

Development of acute tolerance to the EEG effect of propofol in rats

BACKGROUND

A previous study in rats with propofol suggested the development of acute tolerance to the EEG effect. The aim of this study was to evaluate acute tolerance by means of EEG-controlled closed-loop anaesthesia as this approach allows precise determination of drug requirement to maintain a defined drug effect.

METHODS

Ten male Sprague-Dawley rats [weight 402 (40) g, mean (SD)] were included in the study. The EEG was recorded with occipito-occipital needle electrodes and a modified median frequency (mMEF) of the EEG power spectrum was used as a pharmacodynamic control parameter. The propofol infusion rate was controlled by a model-based adaptive algorithm to maintain a set point of mMEF=3 (0.5) Hz for 90 min. The performance of the closed-loop system was characterized by the prediction error PE=(mMEF-set point)/set point. Plasma propofol concentrations were determined from arterial samples by HPLC.

RESULTS

The chosen set point was successfully maintained in all rats. The median (SE) and absolute median values of PE were -5.0 (0.3) and 11.3 (0.2)% respectively. Propofol concentration increased significantly from 2.9 (2.2) microg ml(-1) at the beginning to 5.8 (3.8) microg ml(-1) at 90 min [mean (SD), P<0.05]. The cumulative dose increased linearly, with a mean infusion rate of 0.60 (0.16) mg kg(-1) min(-1). The minimum value of the mean arterial pressure during closed-loop administration of propofol was 130 (24) mm Hg, compared with a baseline value of 141 (12) mm Hg.

CONCLUSIONS

The increase in propofol concentration at constant EEG effect indicates development of acute tolerance to the hypnotic effect of propofol.

Increased propofol requirement during succeeding administrations for electroconvulsive therapy

STUDY OBJECTIVE

To study patients' requirement for propofol dosages during the course of repeated deep sedation for electroconvulsive therapy (ECT).

DESIGN

Prospective study.

SETTING

Outpatient psychiatric clinic in a tertiary-care, university-affiliated, 1100-bed metropolitan hospital.

PATIENTS

30 patients undergoing 5-day successive ECT for depression over a 1-month period.

INTERVENTIONS

Propofol and subsequently succinylcholine were injected intravenously (i.v.) to obtain deep sedation and relaxation followed by a 60 +/- 5 (SD) joules-ECT.

MEASUREMENTS

The dosage that was required to deeply sedate the patients, the duration of the ECT, and interval of time to full wakefulness and coherent response were measured.

MAIN RESULTS

13 of 30 patients 1) required >100% increase in the dose of propofol to achieve the same pharmacological prerequisite sedative endpoint, starting from their third treatment onward; 2) there was a 35% abbreviated duration of the convulsive activity; and 3) there was a 21% shortened interval of time to full wakefulness and coherent communication, starting at the fourth propofol injection.

CONCLUSIONS

Repeated injections of propofol in patients undergoing ECT under deep sedation can induce a tolerance-like reaction to the drug.

Daily general anaesthesia for radiotherapy in unco-operative patients: ingredients for successful management

An unco-operative patient requiring daily radiation therapy presents a difficult clinical problem. After reviewing the paediatric oncology literature addressing the use of general anaesthesia for short medical procedures, we have developed checklists of procedural guidelines and monitoring equipment for the safe use of daily anaesthesia in adult patients who require a fractionated course of radiation therapy. We illustrate this by describing the successful treatment of a woman with autism and Hodgkin's disease who required daily general anaesthesia for immobilization during a 4-week course of radiation therapy. Propofol was used as the primary drug and was not associated with any adverse side-effects. There was no development of tolerance.

The influence of age and administration rate on the brain sensitivity to propofol in rats

BACKGROUND

It is well established that the dose of propofol for induction of anaesthesia is influenced by patient age. This may be explained by differences in pharmacokinetics or pharmacodynamics. To evaluate the effect of age on propofol pharmacodynamics, the brain concentration of propofol at the time of an EEG end-point was used as a measure of CNS sensitivity.

METHODS

Ninety-five rats were assigned to 4 groups. Anaesthesia was induced by continuous propofol infusion at different rates. The dose of propofol and duration of anaesthesia were determined from 23 up to 776 days of age. The rats were killed at 23, 287 or 776 days of age at the EEG end-point and samples of cerebral cortex, midbrain, cerebellum, serum and fat tissue were submitted to HPLC analysis of propofol concentrations.

RESULTS

The induction dose of propofol varied with age and administration rate. Young animals needed a higher dose of propofol. Old animals had higher brain concentrations of propofol at the EEG end-point than young animals. However, propofol concentrations in serum were higher in young animals. The propofol concentration in the brain was influenced by the administration rate.

CONCLUSION

The dose of propofol for induction of anaesthesia in rats is influenced by animal age and administration rate. Young animals need a larger induction dose than old rats, but are more sensitive as measured by the brain concentration of propofol. The larger induction dose in young rats when compared with adults is explained by pharmacokinetic differences rather than by pharmacodynamic changes.