Propofol anaesthesia in spontaneously breathing paediatric patients during magnetic resonance imaging

Lower-Dose Propofol Use for MRI: A Retrospective Review of a Pediatric Sedation Team's Experience

OBJECTIVE

The aim of the study was to evaluate, in children undergoing procedural sedation for magnetic resonance imaging (MRI) scans, whether lower doses of propofol than previously published permitted a high rate of successful MRI completion, whether lower dosages result in a more rapid recovery, and whether age or behavioral diagnosis increases propofol requirements.

METHODS

After institutional review board approval, we retrospectively reviewed the pediatric sedation team's sedation database of children receiving propofol infusion for MRI scans between 2007 and 2016. Data collected included propofol induction dose (in milligrams per kilogram), propofol infusion dose (in micrograms per kilogram per hour), total propofol dose (in milligrams per kilogram and in milligrams per kilogram per hour), and the number of administered ancillary sedative medications. Additional data included the American Society of Anesthesiologist status, sedation duration, recovery duration, and successful completion of MRI. Dosing data were also stratified by age.

RESULTS

A total of 2354 patients met inclusion criteria. Eight percent of patients received propofol infusion alone, 79% received midazolam before their propofol induction, and 13% received a combination of propofol and other drugs. Mean induction dose was 2.2 + 0.9 mg/kg, mean infusion dose was 93.5 + 29.0 μg/kg per minute, and total mean dose was 9.0 + 3.0 mg/kg per hour. Mean recovery time was 44 minutes, and 99.3% of the scans were completed with good images. We noted an increase requirement in the mean induction dose and total dose in children younger than 1 year.

CONCLUSIONS

Propofol infusion doses lower than commonly reported permit successful completion of scans and similar recovery times in a single institution. Younger children require more propofol for successful procedural sedation.

Safety of Propofol versus Nonpropofol-Based Sedation in Children Undergoing Gastrointestinal Endoscopy: A Systematic Review and Meta-Analysis

BACKGROUND

The majority of children who undergo gastrointestinal (GI) endoscopy require anesthesia or procedural sedation for comfort, cooperation, and procedure efficiency. The safety profile of propofol is not well established in children but has been studied in the literature.

OBJECTIVE

The aim of this study is to evaluate and compare the safety of propofol-only sedation for GI endoscopy procedures to other anesthetic regimes in the pediatric population.

METHODS

A search was conducted in the MEDLINE, Embase, and Cochrane Library databases. Randomized clinical trials and prospective cohorts were included in the study.

RESULTS

No significant difference was noted in total complications between the two cohorts with a pooled OR of 1.31 (95% CI: 0.57-3.04, chi2 = 0.053, I2 = 54.31%). The pooled rate of complications in the studies was 23.4% for those receiving propofol only and 18.2% for those receiving other anesthetic regimens. Sensitivity analysis was performed removing a study with a very different control comparison compared to the rest of the studies included. Once excluded, there was minimal heterogeneity in the remaining studies and a significant difference in overall complications was detected, with more complications seen in the propofol-only group compared to the other anesthetic groups (OR 1.87, 95% CI 1.09-3.20).

CONCLUSION

Significantly higher incidence of cardiorespiratory complications was noted in the propofol-only versus other anesthetic regimens in pediatric patients undergoing GI endoscopy in this meta-analysis. However, the overall quality of the evidence is very low.

HOW TO APPLY THIS KNOWLEDGE FOR ROUTINE CLINICAL PRACTICE

Clinicians providing sedation to a pediatric population for GI endoscopy should consider there may be increased risks when using a propofol-only regimen, but further study is needed.

The effect of "multiphase sedation" in the course of computed tomography and magnetic resonance imaging on children, parents and anesthesiologists

BACKGROUND AND OBJECTIVES

We aimed to investigate the effect on children undergoing Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), their parents and attending anesthesiologist of "multiphase sedation" which we define as "the intended sedation level achieved with one or more agents through the same or different routes with more than one administration".

MATERIAL AND METHODS

One hundred children and their parents were randomly allocated to one of two study groups. In phase 1; in Group I the patients were given midazolam (0.5mg.kg(-1)) in 5 mL fruit juice, and the ones in control group (Group II) were given only fruit juice. After intravenous (iv) cannulation; in phase II, boluses of propofol were given to achieve the adequate sedation for imaging. Anxiety scores of children and their parents were recorded using Oucher scale and STAI, respectively, and parental satisfaction was evaluated by visual analogue scale (VAS). The number of attempts for iv cannulation, length of time for preparation, and amount of hypnotics were recorded.

RESULTS

Anxiety state of children was similar between groups before premedication, but later it was lower in Group I. Before procedure, STAI score of parents was similar and later it was lower in Group I. Parental satisfaction in Group I was higher. The number of attempts for iv cannulation and required propofol dose was less in Group I.

CONCLUSION

"Multiphase sedation" procedure provides children to feel less pain and anxiety, and decreases parental anxiety while increasing their satisfaction. It supplies a comfortable and safe sedation, as it provides a short and problem-free preparation process for the attending anesthetist as well.

Propofol anesthesia for children undergoing magnetic resonance imaging: a comparison with isoflurane, nitrous oxide, and a laryngeal mask airway

BACKGROUND

Both propofol infusions with oxygen delivered through nasal cannula and isoflurane/N2O (nitrous oxide) delivered via a laryngeal mask airway (LMA) are used to provide anesthesia for children undergoing magnetic resonance imaging scans. We compared the incidence of adverse events and perioperative physiologic responses in children anesthetized with these 2 regimens.

METHODS

One hundred-fifty healthy children, ages 1 to 10 years, were randomized to receive either a propofol infusion (starting at 300 µg kg·min) with oxygen via nasal cannula (n = 75) or isoflurane with 70% N2O in oxygen delivered via an LMA (n = 75), both after a sevoflurane/N2O/oxygen induction. Adverse airway events, as well as hemodynamic, respiratory, and other physiologic responses were recorded during the magnetic resonance imaging scans and in the postanesthesia care unit by a single research nurse who was blind to the treatments. All parents were contacted postoperatively to complete a postanesthetic follow-up.

RESULTS

All 150 children completed their scans. The frequency of all adverse airway events during emergence and recovery after propofol (12%) was significantly less than that after isoflurane/N2O/LMA (49%) (95% confidence interval for the risk difference was 23%-50%) (P = 0.0001). Hemodynamic responses and recovery times for the 2 treatments were similar. Early recovery, defined as the time interval from admission to the postanesthesia care unit until eye opening and wakefulness (modified Aldrete score >5), after propofol was more rapid than that after isoflurane/N2O/LMA (P = 0.0001 and P = 0.0012, respectively). No scans had to be repeated.

CONCLUSIONS

The frequency of adverse airway events during emergence and recovery after propofol infusion with oxygen by nasal cannula is less than with isoflurane/N2O/LMA in children.

Upper airway size and configuration during propofol-based sedation for magnetic resonance imaging: an analysis of 138 infants and children

BACKGROUND

Propofol is widely used for pediatric sedation. However, increasing depth of propofol sedation is associated with airway narrowing and obstruction. The aim of this study was to objectively assess airway patency during a low-dose propofol-based sedation regimen by measuring upper airway size and configuration with magnetic resonance imaging (MRI) in spontaneously breathing infants and children.

METHODS

Magnetic resonance images of the upper airway were obtained in 138 infants and children, aged up to 6 years. Cross-sectional area, anteroposterior dimension, and transverse dimension were measured at the level of the soft palate, the base of the tongue, and the tip of the epiglottis. Sedation was induced with i.v. midazolam 0.1 mg·kg(-1) , nalbuphine 0.1 mg·kg(-1) , and propofol 1 mg·kg(-1) and maintained with propofol 5 mg·kg(-1) ·h(-1) .

RESULTS

Median (IQR) age was 36 (15, 48) months, and mean body weight was 13.7 ± 5.6 kg. Airway patency was maintained in all infants and children. The narrowest part of the pharyngeal airway was measured at the level of the base of the tongue. Anteroposterior dimensions were narrower than transverse dimensions in all age groups at all measurement sites. Transverse dimensions increased with age at all measurement sites, while anteroposterior dimensions did not increase comparably. No patient demonstrated respiratory or cardiovascular adverse events. All MRI were completed successfully without sedation failure.

CONCLUSION

Airway patency was maintained in all infants and children sedated with this low-dose propofol-based sedation regimen.

Propofol vs pentobarbital for sedation of children undergoing magnetic resonance imaging: results from the Pediatric Sedation Research Consortium

BACKGROUND

Pentobarbital and propofol are commonly used to sedate children undergoing magnetic resonance imaging (MRI). The Pediatric Sedation Research Consortium (PSRC) was created in 2003 to improve pediatric sedation process and outcomes.

OBJECTIVE

To use PSRC records to compare the effectiveness, efficiency and adverse events of propofol vs pentobarbital for sedation of children undergoing MRI.

METHODS

Pediatric Sedation Research Consortium records of children aged 6 months to 6 years who were primarily sedated with either i.v. pentobarbital or propofol were included. Participating PSRC investigators obtained institutional review board approval before data collection.

RESULTS

Of 11 846 sedations for MRI, 7079 met inclusion criteria (propofol: n = 5072; pentobarbital: n = 2007). Demographic details were similar between the two groups. Ideal sedation was produced in 96.45% of the pentobarbital group and in 96.8% of the propofol group (P = 0.478), but pentobarbital was more likely to result in poor sedation cancelling the procedure (OR 5.88; CI 2.24, 15.40). Propofol resulted in physiologic changes more frequently than did pentobarbital (OR 5.69; CI 1.35, 23.97). Pentobarbital was associated with prolonged recovery (OR 16.82; CI 4.98, 56.8), unplanned admission (OR 5.60; CI 1.02, 30.82), vomiting (OR 36.76; CI 4.84, 279.2) and allergic complication (OR 9.15; CI 1.02, 82.34). The incidence of airway complications was not significantly different between the two. The median recovery time for patients receiving propofol was 30 min, whereas for pentobarbital it was 75 min (P < 0.001).

CONCLUSION

Among institutions contributing data to the PSRC, it is found that propofol provides more efficient and effective sedation than pentobarbital for children undergoing MRI. Although apnea occurred with a greater frequency in patients who received propofol, the rate of apnea and airway complications for propofol was not statistically different from that seen in patients who received pentobarbital.

Pediatric procedural sedation by a dedicated nonanesthesiology pediatric sedation service using propofol

OBJECTIVES

To evaluate the success and dosing requirements of propofol in children for prolonged procedural sedation by a nonanesthesiology-based sedation service.

METHODS

The pediatric sedation service at this institution uses propofol as its preferred sedative, and the local guideline suggests using 3 mg/kg for induction and 5 mg kg(-1) h(-1) for maintenance sedation. Doses can be adjusted as needed to individualize successful sedation. A retrospective analysis of patients sedated for 30 minutes or longer was conducted. Patients were stratified into 4 cohorts based on age (<1 year [n = 16], 1-2 years [n = 85], 3-7 years [n = 54], and >7 years [n = 55]) and dosing patterns, success, and adverse effects were investigated.

RESULTS

Two hundred forty-nine patients met the inclusion criteria. Mean age was 4.8 years (SD, 4.1). The mean induction dose was 3.2 mg/kg (range, 0.9-9.7), and the mean maintenance infusion was 5.2 mg kg(-1) h(-1) (range, 0.14-21.3). No differences were seen in the induction doses in the different age cohorts, yet the SD was largest in the youngest cohort compared to any other. Although no differences were seen in maintenance rates by age, the greatest SD for dosing was seen in the oldest cohort. For all ages, all sedations were successful (100%) and unanticipated adverse effects rare (<1%).

CONCLUSIONS

Although it seems that the mean dosing of propofol does not vary significantly with age, there is greater variability in induction dosage for those younger than 1 year and in maintenance dosing for those 7 years or older. The results and general dosing parameters may assist pediatric subspecialists in using propofol for prolonged procedural sedation.

Potential of MR-imaging in the paediatric abdomen

OBJECTIVE

To describe the potential and relevant applications of MR-imaging (MRI) in typical paediatric abdominal conditions and diseases.

METHOD

The commonly used indications, applications, and sequences as well as typical imaging findings of paediatric abdominal MRI are presented and discussed, with emphasis on specific paediatric needs and queries. Only applications as used in routine clinical work are listed, other more sophisticated and advanced techniques will only briefly be mentioned. Furthermore, some aspects of paediatric MR Urography are presented and discussed.

CONCLUSION

Though conventional imaging methods (ultrasound and plain film) are valuable and - particularly in the paediatric abdomen - form the mainstay of routine imaging in paediatric abdominal radiology, some conditions require sectional imaging. MRI is increasingly applied to these queries in neonates, infants and children as an alternative method to CT without any radiation burden, and - when performed adequately and skilfully - can answer most treatment relevant questions. MR will increasingly be applied with new applications and broader availability also with functional information deriving from new equipment and research offering an ideal one stop imaging approach to many conditions also in children.

Multidrug intravenous anesthesia for children undergoing MRI: a comparison with general anesthesia

BACKGROUND

We used a multidrug intravenous anesthesia regimen with midazolam, ketamine, and propofol to provide anesthesia for children during magnetic resonance imaging (MRI). This regimen was compared with general anesthesia in a randomized comparative study. Outcome measures were safety, side effects and recovery variables in addition to adverse events in relation to age strata.

METHODS

The children received either general anesthesia with propofol, vecuronium and isoflurane [general endotracheal anesthesia (GET) group; n=313] or intravenous anesthesia with midazolam, ketamine, and propofol [intravenous anesthesia (MKP) group; n=342]. Treatment assignment was randomized based on the date of the MRI. Physiological parameters were monitored during anesthesia and recovery. Desaturation (SpO2<93%), airway problems, and the need to repeat the scan were recorded. The discharge criteria were stable vital signs, return to baseline consciousness, absence of any side effects, and ability to ambulate.

RESULTS

With the exception of two children (0.6%) in the MKP group, all enrolled children completed the scan. A significantly greater number (2.3%) required a repeat scan in the MKP group (P<0.05) and were sedated with a bolus dose of propofol. The total incidence of side effects was comparable between the MKP (7.7%) and GET groups (7.0%). Infants below the age of 1 year showed a significantly higher incidence of adverse events compared with the other age strata within each group. Within the MKP group, risk ratio was 0.40 and 0.26 when comparing infants aged below 1 year with the two older age strata, respectively. Recovery characteristics were comparable between both groups.

CONCLUSIONS

Intravenous midazolam, ketamine and propofol provides safe and adequate anesthesia, comparable with that obtained from general endotracheal anesthesia, for most children during MRI.

Magnetic resonance imaging anesthesia: new challenges and techniques

PURPOSE OF REVIEW

The increasing use of magnetic resonance imaging as a diagnostic modality has led to increased demand for sedation and monitoring during the procedure. This review is to acquaint the reader with the most recent developments in magnetic resonance imaging diagnostics and to describe the evolving techniques and strategies for patient management.

RECENT FINDINGS

Many centers are meeting the challenges of increasing demand by streamlining their sedation/anesthetic protocols to achieve greater efficiency. Some have enlisted the help of nursing staff who are trained to provide sedation for certain patients. Continued experience in magnetic resonance imaging anesthesia has led to a better understanding of patient needs and decreased the number of failed procedures. The scope of magnetic resonance imaging diagnostics has expanded to include urology, otolaryngology, and neonatal evaluation. Although infants and children constitute the majority of patients, many adults also require anesthesia for magnetic resonance imaging and present their own challenges.

SUMMARY

Anesthesia and sedation during magnetic resonance imaging have a unique set of constraints. However, most of the standards of modern, safe anesthetic care can be met in this environment. The growing experience at many hospitals has demonstrated that a wide range of patients can receive safe care during magnetic resonance imaging.

Fallgruben in der Magnetresonanztomographie

The constantly extending indication spectrum of magnetic resonance imaging (MRI) is a challenge for the anaesthesiologist, who is being increasingly more consulted for assistance during the examination. Due to the special technology of MRI the anaesthetic technique differs substantially from that in the operating theatre. In addition to the permanent strong magnetic field the intermittently used high frequency impulses are also a potential danger for the patient. Patients with metal implants (e.g. cardiac pacemaker) are particularly at risk. For the safe treatment of patients during MRI a special MRI compatible anaesthesia equipment is necessary. Unsuitable devices can lead to malfunctioning or to projectile effects (attracting ferromagnetic objects into the magnet) causing injury to the patients. This paper describes the MRI technology and the associated dangers for the patient as well as the characteristics of the anaesthetic techniques.

Analgesia and local anesthesia during invasive procedures in the neonate

BACKGROUND

Preterm and full-term neonates admitted to the neonatal intensive care unit or elsewhere in the hospital are routinely subjected to invasive procedures that can cause acute pain. Despite published data on the complex behavioral, physiologic, and biochemical responses of these neonates and the detrimental short- and long-term clinical outcomes of exposure to repetitive pain, clinical use of pain-control measures in neonates undergoing invasive procedures remains sporadic and suboptimal. As part of the Newborn Drug Development Initiative, the US Food and Drug Administration and the National Institute of Child Health and Human Development invited a group of international experts to form the Neonatal Pain Control Group to review the therapeutic options for pain management associated with the most commonly performed invasive procedures in neonates and to identify research priorities in this area.

OBJECTIVE

The goal of this article was to review and synthesize the published clinical evidence for the management of pain caused by invasive procedures in preterm and full-term neonates.

METHODS

Clinical studies examining various therapies for procedural pain in neonates were identified by searches of MEDLINE (1980-2004), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2004), the reference lists of review articles, and personal files. The search terms included specific drug names, infant-newborn, infant-preterm, and pain, using the explode function for each key word. The English-language literature was reviewed, and case reports and small case series were discarded.

RESULTS

The most commonly performed invasive procedures in neonates included heel lancing, venipuncture, IV or arterial cannulation, chest tube placement, tracheal intubation or suctioning, lumbar puncture, circumcision, and SC or IM injection. Various drug classes were examined critically, including opioid analgesics, sedative/hypnotic drugs, nonsteroidal anti-inflammatory drugs and acetaminophen, injectable and topical local anesthetics, and sucrose. Research considerations related to each drug category were identified, potential obstacles to the systematic study of these drugs were discussed, and current gaps in knowledge were enumerated to define future research needs. Discussions relating to the optimal design for and ethical constraints on the study of neonatal pain will be published separately. Well-designed clinical trials investigating currently available and new therapies for acute pain in neonates will provide the scientific framework for effective pain management in neonates undergoing invasive procedures.

Propofol anesthesia in spontaneously breathing children undergoing magnetic resonance imaging: comparison of two propofol emulsions

BACKGROUND

This study evaluated a propofol-based anesthesia regimen with spontaneous breathing in pediatric patients scheduled for magnetic resonance imaging (MRI).

METHODS

In this prospective, randomized, double-blind study propofol formulated with long-chain triglycerides (LCT) and mixed medium-chain/long-chain triglycerides (MCT/LCT) were used. Ninety patients aged 2.4 months to 7.3 years were premedicated with intravenous midazolam. Lidocaine was injected prior to propofol to reduce injection pain. Anesthesia was induced and maintained by propofol. Glycopyrronium bromide was administered for saliva reduction. Hemodynamics, blood oxygen saturation and endtidal capnography were continuously monitored. All patients received additional oxygen. The aggregated propofol dose for induction and maintenance of anesthesia was analyzed for therapeutic equivalence. Incidence of injection pain, laboratory safety values, vital signs, and the adverse event profile were analyzed to compare tolerability and safety.

RESULTS

Propofol anesthesia was safe and successful in all children. Both propofol formulations were equivalent regarding dose requirements (mean induction and maintenance doses for anesthesia 2.0-4.0 mg.kg(-1) and 6.0-8.8 mg.kg(-1).h(-1) respectively; aggregated doses 8-13.26 mg.kg(-1)). There were no differences in drug safety such as hemodynamics, spontaneous breathing, injection pain, and laboratory values. Duration of induction and of recovery from anesthesia were short and all examinations were completed with minimal interruption.

CONCLUSIONS

Propofol-based short-term anesthesia was well suited for anesthesia during MRI procedures in the studied pediatric patients. There were no clinically relevant differences between the two propofol formulations.

[MR urography: principles, examination techniques, indications]

MR urography is an evolving and promising technique in the evaluation of the urinary tract. MR urography is currently considered the method of choice for imaging of the renal parenchyma and the collecting systems in patients who cannot undergo routine radiographic studies such as pregnant women, pediatric patients, patients allergic to iodinated contrast agents, or patients with impaired renal function. The future development of MR urography in terms of functional, cellular, and molecular imaging is presently the subject of research. The ability of MR imaging to provide quantitative functional information (e.g., on blood flow, perfusion, glomerular filtration rate, and excretion as well as urine drainage) in addition to morphologic assessment of the parenchyma and the collecting system could lead to a single, "all-in-one approach" examination technique.

Propofol total intravenous anesthesia for MRI in children

BACKGROUND

The aim of this study was to assess clinical signs of airway patency, airway intervention requirements and adverse events in 100 children receiving propofol total intravenous anesthesia for magnetic resonance imaging, with spontaneous ventilation and oxygenation via nasal prongs.

METHODS

Airway patency was clinically assessed and stepwise interventions were performed until a satisfactory airway was achieved. Propofol requirements, vital signs, procedure times and adverse events were also recorded.

RESULTS

Ninety-three per cent of children had no signs of airway obstruction when positioned with a shoulder roll only, two required a chin lift, four required an oral airway and one required lateral positioning. The mean propofol induction dose was 3.9 mg.kg(-1) (range 1.8-6.4 mg.kg(-1)). The mean propofol infusion rate was 193 microg.kg(-1).min(-1) (range 150-250 microg.kg(-1).min(-1)). The initial and final mean respiratory rates were 26 and 23 b.min(-1) (P < 0.05). Movement was more likely at lower infusion rates (mean 175 microg.kg(-1).min(-1)). There were no respiratory or cardiovascular complications (calculated risk: 95% CI = 0-3%). The mean time from end of scan to discharge home was 44 min.

CONCLUSIONS

This study demonstrates good preservation of upper airway patency and rapid recovery using general anesthetic doses of propofol in children.

A case of propofol toxicity: further evidence for a causal mechanism

A 5-month-old boy required sedation after a cleft lip repair. He was sedated with propofol and intermittent fentanyl, requiring escalating doses over the subsequent 48 h. On the second post-operative day he developed a metabolic acidosis followed by multiple cardiac dysrhythmias, hepatic and renal failure. Propofol was stopped. His multisystem organ failure gradually resolved after initiation of charcoal haemoperfusion. Further investigation demonstrated an abnormality in acylcarnitine metabolism, similar to that found in one previous case report.

Clinical and biochemical effects of propofol EDTA vs sevoflurane in healthy infants and young children

BACKGROUND

Propofol is frequently used for the induction and maintenance of anaesthesia in children aged 3 years and older. The present study compared the clinical and chemical effects of propofol containing disodium edetate (Diprivan) with that of sevoflurane in children younger than 3 years of age.

METHODS

This was an open-label, comparative, parallel-group study. Fifty-six healthy children were randomly assigned to receive either propofol (n=28; mean age 14.7 months) or sevoflurane (n=28; mean age 13.2 months) for ambulatory surgical procedures. Anaesthesia was induced with nitrous oxide (60%), oxygen and sevoflurane (8%). In the propofol group, it was followed by an intravenous infusion of propofol at a rate of 200 microg.kg(-1).min(-1). For the sevoflurane group, anaesthesia was maintained with sevoflurane (1.5-2.5%). Haemodynamic measurements, recovery time and side-effects were recorded. Ionized calcium and magnesium concentrations in blood were measured. Statistical analysis was performed using ancova and the Fisher's exact test.

RESULTS

The effects of propofol were similar to those of sevoflurane with respect to haemodynamic profile, recovery times (20 min vs 19.4 min) and side-effects (i.e. vomiting 10.7% vs 7.1%). Throughout the study, there were no significant differences between the mean ionized calcium and ionized magnesium concentrations in the two groups.

CONCLUSIONS

In children younger than 3 years of age, propofol containing ethylenediaminetetraacetic acid has a similar profile to sevoflurane with respect to haemodynamic effects, recovery times, side-effects, ionized calcium and ionized magnesium levels.

Deep sedation with propofol for children undergoing ambulatory magnetic resonance imaging of the brain: experience from a pediatric intensive care unit

OBJECTIVES

Use of intravenous propofol sedation to facilitate completion of magnetic resonance imaging of the brain in children.

DESIGN

Retrospective, cross-sectional.

SETTING

A university-affiliated pediatric intensive care unit.

PATIENTS

A total of 115 children who received intravenous propofol to complete magnetic resonance imaging of the brain January 1 through December 31, 2001.

INTERVENTIONS

Intravenous propofol infusion.

MEASUREMENTS AND MAIN RESULTS

The mean age was 4.2 +/- 3.1 yrs, and there were 63 boys and 52 girls. Sixty-nine percent of patients belonged to ASA physical status class I, and 31% belonged to ASA class II. All studies were completed with satisfactory image quality. The total dose of propofol used to complete a magnetic resonance image of the brain was 4.3 +/- 1.7 mg/kg body weight. The mean duration of sedation induction was 4.5 +/- 3.5 mins. The mean time to recovery (from the end of the procedure) was 20 +/- 15 mins. The duration of the procedure averaged 39 +/- 20 mins, and the time to discharge from the hospital was 50 +/- 21 mins from the end of the procedure. No episodes of hypoxia, apnea, or a need for artificial airway were noted. Systolic blood pressure decreased 10% +/- 13%, but none of the patients met the criteria for hypotension. A telephone call the next day to the family did not reveal any delayed complications.

CONCLUSIONS

Propofol can safely facilitate ambulatory magnetic resonance imaging of the brain in children, and it is associated with brief induction, recovery, and discharge times from the hospital. A drop in blood pressure, although mild and transient, does occur. Therefore, appropriate monitoring and preparedness for cardiorespiratory support are essential.

Childhood obesity: a challenge for the anaesthetist?

The definition of childhood obesity has not been standardized in the past, making studies difficult to compare. In spite of this, the increase in the incidence of childhood obesity is evident and has now reached epidemic proportions. Obese children experience few of the medical complications seen in obese adults. Respiratory physiology appears to be most affected, the degree of which is determined by the level of obesity. Although there is a considerable amount of information on the anaesthetic management of the obese adult, very little has been written concerning the obese child. There is less pathology in the obese child when compared with the adult but some evidence shows a higher likelihood of a critical incident occurring when anaesthetizing such children. This shows that we need to be as worried about anaesthetizing the obese child as we are for the obese adult. This concern should increase with increasing body mass index.

MR urography in children

Thanks to the development of rapid sequences with better resolution, applications of uro MR have rapidly increased in children. Difficulties that remain are related to the variable ages of the patients. It is therefore mandatory to standardize as much as possible the techniques that are used in order to obtain reproducible results. In this review, the examination protocols will be explained. In a second part the current applications in children will be illustrated and discussed, especially in comparison with the other imaging techniques.

Effect of distance and infusion rate on operation of Medfusion 2010 infusion pump during magnetic resonance imaging

STUDY OBJECTIVES

To determine the accuracy and reliability of intravenous infusion, as well as magnetic resonance image effect of the Medfusion 2010 infusion pump (Medex Medical Supplies, Inc., Duluth, GA) at distances of 2, 4, 8, 12, and 16 feet from a 1.5 Tesla MRI magnet over a four-week time interval, using infusion rates that would correspond to those of propofol administration.

DESIGN

Prospective, open-label study.

SETTING

Radiology department MRI in an American academic medical center.

INTERVENTIONS

Five infusion pumps, including one outside the MRI suite as control, were tested. Pumps were evaluated at distances of 2, 4, 8, 12, and 16 feet from a 1.5 Tesla magnet. One pump at distances of 2 and 16 feet was tested during 30 and 90 hours of operation, respectively. Three pumps at distances of 4, 8, and 12 feet were tested during 120 hours of operation. Pump batteries were recharged for 18 hours outside the MRI suite between the 6-hour test periods. Distilled, deionized water was infused from a 30-mL or 60-mL syringe via a 36-inch Medex small-bore extension set into a graduated collection cylinder at rates of 5, 10.5, 21, or 42 mL/hr. Each rate was increased to the next infusion rate level at 30-hour weekly intervals. The collection cylinder with infused water was weighed on an electronic scale accurate to within +/-0.001 g. Analysis of variance and regression analysis were used to analyze data. A p < 0.05 value was considered statistically significant.

MEASUREMENTS AND MAIN RESULTS

There was no significant difference comparing the grams weight of volume measured and the mL volume visualized within and between groups at varying distances from the magnet. Increasing infusion rates resulted in corresponding increases in volume delivered irrespective of the distance from the magnet.

CONCLUSIONS

The Medfusion 2010 infusion pumps were found to be reliable and accurate, without causing failure or any significant degradation of MRI images compared to control at infusion rate of 42 mL/hr at a distance of 2 feet for 30 hours; and a rate of 5.0, 10.5, 21, and 42 mL/hr at 16 feet for 90 hours; and at 4, 8, and 12 feet for 120 hours of operation.

Propofol for pediatric radiotherapy

OBJECTIVE

Pediatric radiotherapy is a day care procedure. In children, anaesthesia is necessary to prevent movement during the therapy. Traditionally intramuscular ketamine is used for these procedure because of its inherent safety in a child who used to be left alone in the cobalt room.

METHODS

This study was designed to explore the efficacy of propofol and ketamine in pediatric radiotherapy in nineteen children. The inclusion criteria was a child fasting for six hours with no fever or URTI in the past week. A child coming to the radiotherapy (RT) unit without an intravenous cannula was given intramuscular ketamine 10 mg/kg and taken for the procedure. Before the child recovered from anaesthesia an intravenous cannula, 20-22G, Vasofix was inserted for subsequent sittings of RT. The child coming with an intravenous cannula was given propofol 2.5 mg/kg with xylocaine (0.1 mg/kg) without adrenaline. The parameters recorded were pulse rate, oxygen saturation and respiratory rate-baseline to every 30 seconds till five minutes. Onset time, recovery time, oral feeding time and any untoward effects like nausea, vomiting, nystagmus were also noted.

RESULT

The drug was graded on a scale of 0-10 according to parental acceptability where 0 is the worst and 10 is the best acceptability. The mean (+/-SD) of all the measured parameters were calculated and compared between the two groups.

CONCLUSION

Propofol was associated with faster onset, better recovery, early oral feeding time, no nausea and vomiting and better parental acceptability. There was no hypotension, bradycardia and oxygen saturation at 60 seconds, which was between 94-95%, was easily treatable with supplementation of oxygen by face mask.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Propofol as a sole agent for paediatric day care diagnostic ophthalmic procedures: comparison with halothane anaesthesia

BACKGROUND

Our aim was to study the feasibility of total intravenous anaesthesia with propofol in spontaneously breathing children undergoing ophthalmic procedures.

METHODS

Fifty-five children (aged 6 months to 5 years) were randomly allocated to receive either propofol bolus (until loss of eyelash reflex) followed by infusion [group P (n=29)] or halothane 3-4% for induction, followed by 1-2% in 70% nitrous oxide and oxygen via face mask [group H (n=28)]. Dose for induction and maintenance, intraoperative adverse events, time to recovery (on an Observer's Assessment of Alertness/Sedation Scale, 5 at each level) and duration of procedure were recorded. All children in both groups, were anaesthetized successfully.

RESULTS

4.0 +/- 0.7 mg x kg(-1) and 5.1 +/- 1.0 mg x kg(-1) of propofol were required for loss of eyelash reflex and tolerance of the ophthalmic speculum, respectively. An infusion rate of 8.3 +/- 1.7 mg x kg(-1) x h(-1) was needed for maintenance of anaesthesia; 3.4 +/- 0.5%, 3.6 +/- 0.4% and 1.4 +/- 0.4% halothane was needed for induction, tolerance of the eye speculum and maintenance of anaesthesia, respectively. Induction and recovery were significantly faster with halothane compared with propofol [induction - 38.3 +/- 6.6 s (group H)/60.9 +/- 15.2 s (group P) (P < 0.001); recovery 12.8 +/- 4.6 min (group H)/27.0 +/- 23.3 min (group P) (P < 0.001)]. Apnoea, coughing and breath-holding were seen only in group H. Group P had significantly higher incidence of involuntary movements (minor degree) (n=6) (P < 0.01).

CONCLUSIONS

Propofol is a feasible option for paediatric diagnostic ophthalmic procedures with the advantage over halothane of providing complete access to the eye.

Anaesthesia with midazolam and S-(+)-ketamine in spontaneously breathing paediatric patients during magnetic resonance imaging

We evaluated safety and efficacy of a sedation technique based on rectal and intravenous S-(+)-ketamine and midazolam to achieve immobilization during Magnetic Resonance Imaging (MRI). Thirty-four paediatric patients were randomly assigned to undergo either the sedation protocol (study group) or general anaesthesia (control group). Imaging was successfully completed in all children. Children in the study group received a rectal bolus (0.5 mg x kg(-1) midazolam and 5 mg x kg(-1) S-(+)-ketamine) and required additional i.v. supplementation (20+/-10 microg x kg(-1) x min(-1) S-(+)-ketamine and 4+/-2 microg x kg(-1) x min(-1) midazolam), spontaneous ventilation was maintained. Transient desaturation occurred once during sedation and four times in the control group (P=0.34). PECO2 was 5.3+/-0.5 kPa (40+/-4 mm Hg) in the study group and 4.1+/-0.6 kPa (31+/-5 mm Hg) in the control group (P<0.001). Induction and discharge times were shorter in the study group (P<0.001), recovery times did not differ significantly between the groups. Our study confirms that a combination of rectal and supplemental intravenous S-(+)-ketamine plus midazolam is a safe and useful alternative to general anaesthesia for MRI in selected paediatric patients.

The pediatric sedation unit: a mechanism for pediatric sedation

OBJECTIVES

We have created a pediatric sedation unit (PSU) in response to the need for uniform, safe, and appropriately monitored sedation and/or analgesia for children undergoing invasive and noninvasive studies or procedures in a large tertiary care medical center. The operational characteristics of the PSU are described in this report, as is our clinical experience in the first 8 months of operation.

METHODS

A retrospective review of quality assurance data was performed. These data included patient demographics and chronic medical diagnoses, procedure, or study performed; sedative or analgesic medication given; complications (defined prospectively); and sedation and monitoring time. Patient-specific medical records related to the procedure and sedation were reviewed if a complication was noted in the quality assurance data.

RESULTS

Briefly, the PSU was staffed with an intensivist and pediatric intensive care unit nurses. Patients were admitted to the PSU and assessed medically for risk factors during sedation. Continuous heart rate, respiratory rate, and pulse oximetry monitoring were used, and blood pressure was determined every 5 minutes. After sedation and stabilization, with monitoring continued, the patient was transported to the site to undergo the procedure or study. The pediatric intensive care unit nurse remained with the patient at all times. All necessary emergency equipment was transported with the patient. After the procedure or study was completed, the patient was returned to the PSU for recovery to predetermined parameters. We were able to analyze 458 episodes of sedation for this review. Procedures and studies included radiologic examinations, cardiac catheterization, orthopedic manipulations, solid organ and bone marrow biopsy, gastrointestinal endoscopy, bronchoscopy, evoked potential measurements, and others. Patients were 2 weeks to 32 years of age. The average time from initiation of sedation to last dose of medication administered was 84 minutes. The average time from initiation of sedation to full recovery was 120 minutes. Sedative and analgesia medications use was not standardized; however, the majority of children needing sedation received propofol or midazolam. For patients requiring analgesia, ketamine or fentanyl was added. In 79 of 458 (12%) sedation episodes, complications were documented. Mild hypotension (4.4%), pulse oximetry <93% (2.6%), apnea (1.5%), and transient airway obstruction (1.3%) were the most common complications noted. Cancellation of 11 (2.4%) procedures was attributable to complications. No long-term morbidity or mortality was seen.

CONCLUSIONS

Many children require sedation or analgesia during procedures or studies. Safe sedation is best ensured by appropriate presedation risk assessment and with monitoring by a care provider trained in resuscitative measures who is not involved in performing the procedure itself. Uniformity of care in a large institution is a standard met by the creation of a centralized service, with active input from the department of anesthesiology. We present the PSU as a model for achieving these goals.