The Effects of Small-Dose Ketamine on Propofol Sedation: Respiration, Postoperative Mood, Perception, Cognition, and Pain

Combination of ketamine and propofol versus either agent alone for procedural sedation in the emergency department

PURPOSE

The safety of using ketamine-propofol combinations as an alternative to using either agent alone for procedural sedation is discussed.

SUMMARY

A total of 10 trials comparing the combination of ketamine and propofol with either agent alone for procedural sedation in the emergency department were examined. The evidence reviewed suggests that combining these agents may help to minimize adverse effects such as hypotension and respiratory depression. Ketamine is not commonly used as a single agent in adults because of the risk for emergence reactions; however, when combined with propofol, no significant increase in this adverse effect was found compared with propofol monotherapy. Administering ketamine and propofol can be accomplished by using a two-syringe technique or combining both medications into a single syringe. When two syringes are used, a ketamine 0.3-0.5-mg/kg i.v. bolus dose is administered, followed by a propofol 0.4-1-mg/kg i.v. bolus dose. Sedation is maintained with intermittent i.v. boluses of propofol 0.1-0.5 mg/kg. A 1:1 ratio of ketamine and propofol can also be combined into a single syringe by using the same concentration (10 mg/mL) and equal volumes of each drug, yielding a final concentration of 5 mg/mL for each component.

CONCLUSION

The combined use of ketamine and propofol is a reasonable alternative to propofol alone for procedural sedation in patients at higher risk for respiratory depression or hypotension. Use of the combination requires the development of standardized protocols for drug preparation and dosage to minimize the potential for errors.

Comparison of propofol versus propofol-ketamine combination in pediatric oncologic procedures performed by non-anesthesiologists

BACKGROUND

Limited data are available on the best option (short acting sedatives, opioids, or ketamine) in oncologic procedural sedation performed by non-anesthesiologists. The aim of the present prospective study is to compare the safety and efficacy of propofol-ketamine versus propofol alone, managed by trained pediatricians, in children with cancer undergoing painful procedures.

PROCEDURES

Data on 121 children with acute lymphatic leukemia (ALL) undergoing procedural sedations (lumbar punctures and bone marrow aspirations) were prospectively collected and included drug doses, side effects, pain assessment, and sedation degree. Children were randomly assigned to one of the two groups: P (n = 62) receiving propofol alone and K (n = 59) in whom a ketamine-propofol combination was used.

RESULTS

In group K, the total dose of propofol required was significantly lower than in group P (3.9 ± 3.6 mg/kg vs. 5.1 ± 3.6 mg/kg; P < 0.001). The incidence of hypotension was also significantly lower (11% vs. 39%; P < 0.001). Major O(2) desaturations (defined as SatO(2) < 88%) occurred principally in group P (7 vs. 1; P = 0.05). Both best analgesia and shorter recovery time were obtained with the propofol-ketamine association. No differences were observed in the degree of sedation and in the awakening quality score between the two groups.

CONCLUSIONS

The combination of propofol and ketamine produced statistically significant clinical advantages combined with a higher profile of safety in children with cancer undergoing painful procedures.

Ketamine/propofol versus midazolam/fentanyl for procedural sedation and analgesia in the emergency department: a randomized, prospective, double-blind trial

OBJECTIVES

The authors performed a prospective, double-blinded, randomized trial with emergency department (ED) patients requiring procedural sedation and analgesia (PSA) for repair of deep traumatic lacerations and reduction of bone fractures, to compare the ketamine/propofol (ketofol) combination with the midazolam/fentanyl (MF) combination.

METHODS

Sixty-two patients scheduled for PSA who presented between January 2009 and June 2009 were enrolled prospectively. Thirty-one were randomly assigned to the ketofol group, and 31 were assigned to the MF group.

RESULTS

The median starting doses were 0.75 mg/kg of both ketamine and propofol (interquartile range [IQR] = 0.75 to 1.5 mg/kg), 0.04 mg/kg midazolam (IQR = 0.04 to 0.06 mg/kg), and 2 μg/kg fentanyl (IQR = 2 to 3 μg/kg). There were no significant differences in sedation time between the groups. There were no differences in physician satisfaction (p = 0.065). Perceived pain in the ketofol group, as measured by the Visual Analog Scale (VAS), was significantly lower than in the MF group (median ketofol = 0, IQR = 0-1 vs. median MF = 3, IQR = 1-6; p < 0.001). Only one patient in each group required bag-mask ventilation, and neither of them were intubated.

CONCLUSIONS

The ketamine/propofol combination provides adequate sedation and analgesia for painful procedures and appears to be a safe and useful technique in the ED.

Use of ketofol for procedural sedation and analgesia in children with hematological diseases

BACKGROUND

The aim of this study was to evaluate the effectiveness and safety of intravenous ketamine-propofol admixture ("ketofol") in the same syringe for procedural sedation and analgesia in children undergoing bone marrow aspiration.

METHODS

This was a prospective, observational pilot study. Patients aged between 4 and 12 years requiring sedation for bone marrow aspiration were included. Ketofol (1:1 mixture of ketamine 10 mg/mL and propofol 10 mg/mL) was given intravenously in 0.5 mg/kg aliquots each with a 1-min interval and titrated to reach sedation levels of 3 or 4 (Ramsay score). The primary outcome was patient satisfaction with the degree of sedation. Secondary outcomes included injection pain, total sedation time, recovery time, hemodynamic and respiratory parameters, and adverse events.

RESULTS

A total of 20 patients were enrolled in the study. The median total dose of ketofol administered was 1.25 mg/kg each of propofol and ketamine (95%CI 0.77-2 mg/kg). The median score on the visual analog scale was 0 (extremely comfortable) (0-1.5; 95%CI 0.2-2.2). Median recovery time was 23 min (20.5-28 min; 95%CI 17.1-51.2). The incidence of injection pain was 2/20. Two patients had transient diplopia and one child reported dreams. No patients had hypotension, vomiting or required airway intervention.

CONCLUSION

Ketofol provided effective sedation, which was reflected in the high degree of satisfaction recorded by children requiring procedural sedation and analgesia for bone marrow aspiration. We also observed rapid recovery and no clinically significant complications. A large number of patients is required to evaluate and validate these findings.

A randomized controlled trial of ketamine/propofol versus propofol alone for emergency department procedural sedation

STUDY OBJECTIVE

We compare the frequency of respiratory depression during emergency department procedural sedation with ketamine plus propofol versus propofol alone. Secondary outcomes are provider satisfaction, sedation quality, and total propofol dose.

METHODS

In this randomized, double-blind, placebo-controlled trial, healthy children and adults undergoing procedural sedation were pretreated with intravenous fentanyl and then randomized to receive either intravenous ketamine 0.5 mg/kg or placebo. In both groups, this procedure was immediately followed by intravenous propofol 1 mg/kg, with repeated doses of 0.5 mg/kg as needed to achieve and maintain sedation. Respiratory depression was defined according to any of 5 predefined markers. Provider satisfaction was scored on a 5-point scale, sedation quality with the Colorado Behavioral Numerical Pain Scale, and propofol dose according to the total number of milligrams of propofol administered.

RESULTS

The incidence of respiratory depression was similar between the ketamine/propofol (21/97; 22%) and propofol-alone (27/96; 28%) groups, difference 6% (95% confidence interval -6% to 18%). With ketamine/propofol compared with propofol alone, treating physicians and nurses were more satisfied, less propofol was administered, and there was a trend toward better sedation quality.

CONCLUSION

Compared with procedural sedation with propofol alone, the combination of ketamine and propofol did not reduce the incidence of respiratory depression but resulted in greater provider satisfaction, less propofol administration, and perhaps better sedation quality.

A blinded, randomized controlled trial to evaluate ketamine/propofol versus ketamine alone for procedural sedation in children

STUDY OBJECTIVE

The primary objective is to compare total sedation time when ketamine/propofol is used compared with ketamine alone for pediatric procedural sedation and analgesia. Secondary objectives include time to recovery, adverse events, efficacy, and satisfaction scores.

METHODS

Children (aged 2 to 17 years) requiring procedural sedation and analgesia for management of an isolated orthopedic extremity injury were randomized to receive either ketamine/propofol or ketamine. Physicians, nurses, research assistants, and patients were blinded. Ketamine/propofol patients received an initial intravenous bolus dose of ketamine 0.5 mg/kg and propofol 0.5 mg/kg, followed by propofol 0.5 mg/kg and saline solution placebo every 2 minutes, titrated to deep sedation. Ketamine patients received an initial intravenous bolus dose of ketamine 1.0 mg/kg and Intralipid placebo, followed by ketamine 0.25 mg/kg and Intralipid placebo every 2 minutes, as required.

RESULTS

One hundred thirty-six patients (67 ketamine/propofol, 69 ketamine) completed the trial. Median total sedation time was shorter (P=0.04) with ketamine/propofol (13 minutes) than with ketamine (16 minutes) alone (Δ -3 minutes; 95% confidence interval [CI] -5 to -2 minutes). Median recovery time was faster with ketamine/propofol (10 minutes) than with ketamine (12 minutes) alone (Δ -2 minutes; 95% CI -4 to -1 minute). There was less vomiting in the ketamine/propofol (2%) group compared with the ketamine (12%) group (Δ -10%; 95% CI -18% to -2%). All satisfaction scores were higher (P<0.05) with ketamine/propofol.

CONCLUSION

When compared with ketamine alone for pediatric orthopedic reductions, the combination of ketamine and propofol produced slightly faster recoveries while also demonstrating less vomiting, higher satisfaction scores, and similar efficacy and airway complications.

Office based--is my anesthetic care any different? Assessment and management

Office-based anesthesia (OBA) is a unique and challenging venue, and, although the clinical outcomes have not been evaluated extensively, existing data indicate a need for increased regulation and additional education. Outcomes in OBA can be improved by education not only of anesthesiologists but also of surgeons, proceduralists, and nursing staff. Legislators must be educated so that appropriate regulations are instituted governing the practice of office-based surgery and the lay public must be educated to make wise, informed decisions about choice of surgery location. The leadership of societies, along with support from the membership, must play a key role in this educational process; only then can OBA become as safe as the anesthesia care in traditional venues.

Comparison of propofol versus propofol-ketamine combination for sedation during spinal anesthesia in children: randomized clinical trial of efficacy and safety

OBJECTIVES

This study was designed to compare the efficacy and safety of propofol vs propofol-ketamine combination for sedation during pediatric spinal anesthesia.

METHODS

Forty children, aged 3-8 undergoing spinal anesthesia for lower abdominal surgeries were included. Participants were randomly assigned into two groups. Group 1 received propofol bolus of 2 mg.kg(-1) followed by an infusion of 4 mg.kg(-1).h(-1). Group 2 received a combination of 1.6 mg.kg(-1) propofol and 0.4 mg.kg(-1) ketamine followed by an infusion of 3.2 mg.kg(-1).h(-1) and 0.8 mg.kg(-1).h(-1), respectively. The infusion rate was titrated to keep the child sedated at University of Michigan Sedation Score of 3. The heart rate, blood pressure, respiratory rate and oxygen saturation were recorded every 5 min. The episodes of spontaneous body movements and requirement of supplemental sedation were recorded. The postoperative recovery was assessed by modified Aldrette score.

RESULTS

Seventeen patients in group 1 and four patients in group 2 (P < 0.001) required extra boluses of study drug to prevent movements during lumbar puncture. Four patients experienced respiratory depression and three airway obstruction in group 1 when compared to one patient each in group 2 (P < 0.05). The recovery time was similar in both groups. None of the patient had postoperative nausea/vomiting or psychomimetic reactions.

CONCLUSIONS

Propofol-ketamine combination provided better quality of sedation with lesser complications than propofol alone and thus can be a good option for sedation during spinal anesthesia in children.

Comparison of propofol-fentanyl with propofol-fentanyl-ketamine combination in pediatric patients undergoing interventional radiology procedures

BACKGROUND

With an increase in the frequency of interventional radiology procedures in pediatrics, there has been a corresponding increase in demand for procedural sedation to facilitate them. The purpose of our study was to compare the frequency of adverse effects, sedation level, patient recovery characteristics in pediatric patients receiving intravenous propofol fentanyl combination with or without ketamine for interventional radiology procedures. Our main hypothesis was that the addition of ketamine would decrease propofol/fentanyl associated desaturation.

METHODS AND MATERIALS

Sixty consenting American Society of Anesthesia physical status I-III pediatric patients undergoing interventional radiology procedures under sedation were studied according to a randomized, double-blinded, institutional review board approved protocol. Group 1 received propofol 0.5 mg.kg(-1) + fentanyl 1 microg.kg(-1) + ketamine 0.5 mg.kg(-1), and group 2 received propofol 0.5 mg.kg(-1) + fentanyl 1 microg.kg(-1) + same volume of %0.9 NaCl intravenously.

RESULTS

While apnea was not observed in any of the groups, there were three cases (10%) in group 1, and nine cases (30%) in group 2 with oxygen desaturation (P = 0.052). In group 1, 12 (40%) patients and, in group 2, 21 (70%) patients required supplemental propofol during the procedure (P = 0.021). There was no evidence for difference between groups in terms of other side effects except nystagmus.

CONCLUSIONS

In conclusion, addition of low dose ketamine to propofol-fentanyl combination decreased the risk of desaturation and it also decreased the need for supplemental propofol dosage in pediatric patients at interventional radiology procedures.

Subdissociative-dose ketamine versus fentanyl for analgesia during propofol procedural sedation: a randomized clinical trial

OBJECTIVES

The authors sought to compare the safety and efficacy of subdissociative-dose ketamine versus fentanyl as adjunct analgesics for emergency department (ED) procedural sedation and analgesia (PSA) with propofol.

METHODS

This double-blind, randomized trial enrolled American Society of Anesthesiology (ASA) Class I or II ED patients, aged 14-65 years, requiring PSA for orthopedic reduction or abscess drainage. Subjects received 0.3 mg/kg ketamine or 1.5 mug/kg fentanyl intravenously (IV), followed by IV propofol titrated to deep sedation. Supplemental oxygen was not routinely administered. The primary outcomes were the frequency and severity of cardiorespiratory events and interventions, rated using a composite intrasedation event rating scale. Secondary outcomes included the frequency of specific scale component events, propofol doses required to achieve and maintain sedation, times to sedation and recovery, and physician and patient satisfaction.

RESULTS

Sixty-three patients were enrolled. Of patients who received fentanyl, 26/31 (83.9%) had an intrasedation event versus 15/32 (46.9%) of those who received ketamine. Events prospectively rated as moderate or severe were seen in 16/31 (51.6%) of fentanyl subjects versus 7/32 (21.9%) of ketamine subjects. Patients receiving fentanyl had 5.1 (95% confidence interval [CI] = 1.9 to 13.6; p < 0.001) times the odds of having a more serious intrasedation event rating than patients receiving ketamine. There were no significant differences in secondary outcomes, apart from higher propofol doses in the ketamine arm.

CONCLUSIONS

Subdissociative-dose ketamine is safer than fentanyl for ED PSA with propofol and appears to have similar efficacy.

Neuroprotective effects of propofol in acute cerebral injury

Propofol (2,6-diisopropylphenol) is one of the most popular agents used for induction of anesthesia and long-term sedation, owing to its favorable pharmacokinetic profile, which ensures a rapid recovery even after prolonged administration. A neuroprotective effect, beyond that related to the decrease in cerebral metabolic rate for oxygen, has been shown to be present in many in vitro and in vivo established experimental models of mild/moderate acute cerebral ischemia. Experimental studies on traumatic brain injury are limited and less encouraging. Despite the experimental results and the positive effects on cerebral physiology (propofol reduces cerebral blood flow but maintains coupling with cerebral metabolic rate for oxygen and decreases intracranial pressure, allowing optimal intraoperative conditions during neurosurgical operations), no clinical study has yet indicated that propofol may be superior to other anesthetics in improving the neurological outcome following acute cerebral injury. Therefore, propofol cannot be indicated as an established clinical neuroprotectant per se, but it might play an important role in the so-called multimodal neuroprotection, a global strategy for the treatment of acute injury of the brain that includes preservation of cerebral perfusion, temperature control, prevention of infections, and tight glycemic control.

Ketamine as an adjunct to postoperative pain management in opioid tolerant patients after spinal fusions: a prospective randomized trial

Management of acute postoperative pain is challenging, particularly in patients with preexisting narcotic dependency. Ketamine has been used at subanesthetic doses as a N-methyl D-aspartate (NMDA) receptor antagonist to block the processing of nociceptive input in chronic pain syndromes. This prospective randomized study was designed to assess the use of ketamine as an adjunct to acute pain management in narcotic tolerant patients after spinal fusions. Twenty-six patients for 1-2 level posterior lumbar fusions with segmental instrumentation were randomly assigned to receive ketamine or act as a control. Patients in the ketamine group received 0.2 mg/kg on induction of general anesthesia and then 2 mcg kg(-1) hour(-1) for the next 24 hours. Patients were extubated in the operating room and within 15 minutes of arriving in the Post Anesthesia Care Unit (PACU) were started on intravenous patient-controlled analgesia (PCA) hydromorphone without a basal infusion. Patients were assessed for pain (numerical rating scale [NRS]), narcotic use, level of sedation, delirium, and physical therapy milestones until discharge. The ketamine group had significantly less pain during their first postoperative hour in the PACU (NRS 4.8 vs 8.7) and continued to have less pain during the first postoperative day at rest (3.6 vs 5.5) and with physical therapy (5.6 vs 8.0). Three patients in the control group failed PCA pain management and were converted to intravenous ketamine infusions when their pain scores improved. Patients in the ketamine group required less hydromorphone than the control group, but the differences were not significant. Subanesthetic doses of ketamine reduced postoperative pain in narcotic tolerant patients undergoing posterior spine fusions.

Ketamine-propofol combination sedation for fracture reduction in the pediatric emergency department

OBJECTIVES

To evaluate the time of onset and recovery from and the efficacy and safety of intravenous ketamine-propofol sedation for reduction of forearm fractures in the pediatric emergency department setting.

STUDY DESIGN

Prospective, observational pilot study.

METHODS

Children presenting to an urban pediatric emergency department requiring sedation for closed reduction of forearm fractures received ketamine 0.5 mg/kg and propofol 1 mg/kg. We measured time intervals from drug administration to reduction, recovery, and attainment of discharge criteria, and obtained ratings of depth of sedation, pain, and ease of reduction. A follow-up survey elicited patient recall, parental satisfaction, and delayed complications. Complications were recorded during the procedure and by chart review.

RESULTS

Reduction was successful in 19 of 20 patients with one requiring open reduction. Median time intervals measured from initiation of ketamine injection were 5 minutes to reduction completion, 10 minutes to first purposeful response, and 38 minutes to suitability for discharge. Three patients recalled reduction or casting, but in no case was reduction reported to be the most painful aspect of visit. Emergency physicians and orthopedic residents rated sedation and ease of reduction favorably. Complications included mild hypoxia, vomiting, and transient ataxia. No apnea, hemodynamic compromise, dysphoria, or injection pain occurred.

CONCLUSIONS

In this pilot study, the combination of ketamine and propofol provided effective sedation with rapid recovery and no clinically significant complications for children requiring closed reduction of forearm fractures.

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.

Premedication with orally administered lorazepam in adults undergoing ERCP: a randomized double-blind study

BACKGROUND

Restlessness often complicates ERCP and may be a reason for premature termination of the procedure.

OBJECTIVE

Our purpose was to evaluate whether a premedication with orally administered lorazepam could reduce the need for sedatives and improve sedation quality.

DESIGN

Randomized double-blind trial.

SETTING

Therapeutic ERCP with an intravenous sedation containing midazolam, propofol, and S(+)-ketamine.

PATIENTS

95 inpatients (aged 20-91 years).

INTERVENTIONS

1 mg of lorazepam (n=47) or placebo (n=48) given orally before ERCP.

MAIN OUTCOME MEASUREMENT

Total amount of administered propofol.

RESULTS

Heart rate, blood pressure, number of oxygen desaturations, and states of restlessness did not differ between the groups. The same amount of midazolam was administered in both groups. There was no significant difference in the total amount of propofol to achieve adequate sedation (lorazepam vs placebo: 71+/-5 vs 63+/-4 microg/kg/min, mean+/-SE). Paradoxically, patients pretreated with lorazepam even needed more propofol in the early phase of sedation (275+/-39 vs 159+/-37 microg/kg in minutes 5-10, P<.05) and the total amount of ketamine administered was higher in this group as well (15.8+/-1.4 vs 11.3+/-1.2 microg/kg/min, P<.05). In both groups there were high rates of satisfaction with the course of the procedure evaluated both by the endoscopists and the patients.

CONCLUSION

The trial failed to show an advantage of an oral premedication with lorazepam. The amount of sedatives administered in the lorazepam group even tended to be higher. A premedication with lorazepam may be counterproductive when followed by sedation containing another benzodiazepine.

Simple harmonic scalpel hemorrhoidectomy utilizing local anesthesia combined with intravenous sedation: a safe and rapid alternative to conventional hemorrhoidectomy

BACKGROUND

Harmonic Scalpel(R) hemorrhoidectomy (HSH) is an established surgical therapy for the treatment of symptomatic grade III and IV hemorrhoids. Hemorrhoid surgery is still being performed as an inpatient procedure with general or regional anesthesia in many centers today. There was a trend toward performing hemorrhoid surgery as an ambulatory procedure using local anesthesia supplemented with intravenous sedation. The aim of the current study was to evaluate the safety and efficacy of HSH performed with combination local anesthesia and intravenous sedation in an ambulatory surgical center.

MATERIALS AND METHODS

A retrospective review was performed on the clinical charts of all patients undergoing HSH in an ambulatory surgical center from 2001 to 2005. All hemorrhoidectomies were attempted under propofol/ketamine intravenous sedation and local anesthesia in the prone position. A simple, open technique without routine suture was used.

RESULTS

During the study period, 180 patients (70 females) underwent HSM. Mean procedure and total operating room time were 12 and 28 min, respectively. One patient (0.6%) was converted to general endotracheal anesthesia. Ten patients (5.6%) required post anesthesia care unit (PACU) observation. All patients were discharged home after the procedure. Postoperative complications occurred in 19 patients (10.6%). There were no reoperations and the total readmission rate was 3.7%.

CONCLUSION

HSH performed with a combination of intravenous sedation and local anesthesia is safe and effective in the ambulatory surgery setting. The combined technique was associated with a rate of complications comparable to published series utilizing conventional hemorrhoidectomy techniques. Added benefits include shorter hospital stay and a potential for cost savings.

Deep sedation with intravenous infusion of combined propofol and ketamine during dressing changes and whirlpool bath in patients with severe epidermolysis bullosa

Continuous i.v. infusion of propofol, or propofol plus ketamine for deep sedation and analgesia was carried out in two patients with severe epidermolysis bullosa (EB) during extensive dressing changes and deep whirlpool baths. Intermittent small doses of narcotics were given as supplement for pain relief as needed. Both patients had typical features of severe EB, including extremity contractures, severe digit deformity, difficult airways, extensive blisters and broken skin with denuded areas and severe wound infections. SpO(2) was roughly estimated by holding the probe around the earlobe periodically and no other monitors could be applied because of the skin conditions and the settings of the procedures. Retrospective anesthesia record review showed that the combined propofol and ketamine infusions provided satisfactory sedation with significantly reduced narcotic requirements compared with propofol alone. There were no noticeable side effects when ketamine was added. Ketamine appears to be a good addition to propofol and narcotics to provide sedation and analgesia when there are great concerns for respiration depression, apnea, difficult pain management and potential unstable hemodynamics during dressing changes and whirlpool baths in severe EB patients.

Low-dose ketamine in addition to propofol for procedural sedation and analgesia in the emergency department

OBJECTIVE

To evaluate the efficacy and safety of low-dose intravenous ketamine in addition to intravenous propofol for procedural sedation and analgesia in the emergency department (ED).

DATA SOURCES

Articles were identified using PubMed (1949-February 2007), MEDLINE (1966-February 2007), EMBASE (1980-February 2007), BioMed Central (to February 2007), the Cochrane Library (to February 2007), International Pharmaceutical Abstracts, and Google Scholar (until February 2007). Reference citations from retrieved publications were also reviewed. Search terms included ketamine, propofol, ketamine-propofol, ketofol, combination, sedation, procedural sedation, conscious sedation, and emergency department.

STUDY SELECTION AND DATA EXTRACTION

All articles on prospective procedural sedation that were published or translated into English and that compared combination ketamine-propofol with an appropriate comparator group were included. Clinically relevant safety endpoints included the frequency of significant hemodynamic and respiratory compromise warranting medical intervention, nausea, vomiting, and emergence reactions. Time until hospital discharge criteria were met and patient satisfaction scores were efficacy endpoints of interest.

DATA SYNTHESIS

Of the 11 trials included in this review, most had small sample sizes and were conducted in non-ED settings. The ketamine-propofol combination demonstrated no additional efficacy over propofol in terms of time to discharge. Although fewer patients given the ketamine-propofol combination experienced significant hemodynamic and respiratory compromise, need for active interventions, including fluid or vasopressor administration, supplemental oxygen, or assisted ventilation did not differ between groups. Patients who received higher doses of adjuvant ketamine reported an increased incidence of nausea, vomiting, and emergence reactions following the procedure. Few studies reported patient satisfaction scores postprocedure, and effect of ketaminepropofol on time-to-discharge criteria met was inconclusive.

CONCLUSIONS

At this time, insufficient clinical evidence exists to recommend the routine use of low-dose ketamine with propofol for procedural sedation in the ED setting.

Propofol reduces the incidence of emergence agitation in preschool-aged children as well as in school-aged children: a comparison with sevoflurane

PURPOSE

Young age is considered as one of the factors associated with emergence agitation (EA) following sevoflurane anesthesia. The relationship between EA following propofol anesthesia and young age has not yet been examined. This study was designed to compare the incidence of EA in younger children and older children following either propofol or sevoflurane anesthesia.

METHODS

Ninety-six preschool-aged (2-5 years) children and 90 school-aged (6-11 years) children (American Society of Anesthesiologists [ASA] I or II) scheduled to undergo otorhinolaryngological surgery were randomly assigned to receive either propofol or sevoflurane. These children were divided into the following four groups: propofol-preschool (P-pre), sevoflurane-preschool (S-pre), propofol-school (P-school), and sevoflurane-school (S-school) groups. Recovery times and incidence of EA were compared among the four groups.

RESULTS

We observed that the recovery times were similar in the four groups. After extubation, the incidence of EA in the S-pre group was significantly higher than that in the other groups. After eye opening, the incidence of EA in the S-pre and S-school groups was significantly higher than that in the P-pre or P-school groups. At all recovery times, no difference was observed in the incidence of EA between the P-pre and P-school groups.

CONCLUSION

Propofol, in comparison with sevoflurane, resulted in a lower incidence of EA, with no relation to age.

A Prospective Evaluation of “Ketofol” (Ketamine/Propofol Combination) for Procedural Sedation and Analgesia in the Emergency Department

STUDY OBJECTIVE

We evaluate the effectiveness and consider the safety of intravenous ketamine/propofol combination ("ketofol") in the same syringe for procedural sedation and analgesia in the emergency department (ED).

METHODS

A prospective case series of consecutive ketofol procedural sedation and analgesia events in the ED of a trauma-receiving community teaching hospital from July 2005 to February 2006 was studied. Patients of all ages, with any comorbid conditions, were included. Ketofol (1:1 mixture of ketamine 10 mg/mL and propofol 10 mg/mL) was administered intravenously at the discretion of the treating physician by using titrated aliquots. The presence or absence of adverse events was documented, as were procedural success, recovery time, and physician, nurse, and patient satisfaction. Physiologic data were recorded with established hospital procedural sedation and analgesia guidelines.

RESULTS

One hundred fourteen procedural sedation and analgesia events using ketofol were performed for primarily orthopedic procedures. The median dose of medication administered was ketamine at 0.75 mg/kg and propofol at 0.75 mg/kg (range 0.2 to 2.05 mg/kg each of propofol and ketamine; interquartile range [IQR] 0.6 to 1.0 mg/kg). Procedures were successfully performed without adjunctive sedatives in 110 (96.5%) patients. Three patients (2.6%; 95% confidence interval [CI] 0.6% to 7.5%) had transient hypoxia; of these, 1 (0.9%; 95% CI 0.02% to 4.8%) required bag-valve-mask ventilation. Four patients (3.5%; 95% CI 1.0% to 8.7%) required repositioning for airway malalignment, 4 patients (3.5%; 95% CI 1.0% to 8.7%) required adjunctive medication for sedation, and 3 patients (2.6%; 95% CI 0.6% to 7.5%) had mild unpleasant emergence, of whom 1 (0.9%; 95% CI 0.02% to 4.8%) received midazolam. No patient had hypotension or vomiting or received endotracheal intubation. Median recovery time was 15 minutes (range 5 to 45 minutes; IQR 12 to 19 minutes). Median physician, nurse, and patient satisfaction scores were 10 on a 1-to-10 scale.

CONCLUSION

Ketofol procedural sedation and analgesia is effective and appears to be safe for painful procedures in the ED. Few adverse events occurred and were either self-limited or responded to minimal interventions. Recoveries were rapid, and staff and patients were highly satisfied.

Combination propofol/ketamine is a safe and efficient anesthetic approach to anorectal surgery

PURPOSE

Concerns persist regarding respiratory complications from combination deep intravenous sedation and local anesthesia for prone position anorectal surgery. We examined the safety and efficacy of this approach by using a propofol-based and ketamine-based technique.

METHODS

A retrospective review was conducted on all patients undergoing anorectal surgery. Outcomes (perioperative times, specific complications) were compared with respect to operative position and anesthetic approach. Significance was determined using Student's t-test and chi-squared analysis.

RESULTS

Surgery was performed on 448 patients during a three-year period. There was no significant difference in the two anesthetic groups with regard to age and gender. There were 19 anesthesia-related adverse events occurring in the study group (Monitored Anesthesia Care Group): nausea and vomiting (n = 8), airway obstruction necessitating conversion to general anesthesia (n = 2), excessive pain (n = 2), urinary retention (n = 5), and hospital readmission (n = 2). These occurred in <5 percent of those receiving the combination technique (19/407). Although there was no difference in total procedural time, there was a significant difference in total time spent in the operating room (P = 0.001) and in the hospital overall (P = 0.002). Of the patients receiving combination technique anesthesia, only 31 (7 percent) required the use of the postanesthesia care unit. All patients receiving general anesthesia (n = 23) required the postanesthesia care unit.

CONCLUSIONS

Combination deep intravenous sedation with local anesthesia based on propofol and ketamine is a safe and effective technique for prone-position anorectal surgery. It results in decreased use of the postanesthesia care unit and earlier hospital discharge, reflecting a more efficient use of hospital resources.

Liposuction anesthesia techniques

This article discusses intravenous sedation, the authors' anesthesia of choice when performing most esthetic body contour refinement procedures. This technique is comfortable, safe, contemporary, and beneficial to the patient and medical crew. The preanesthesia evaluation is emphasized as a safety and high-quality action to any anesthesia procedure. Alternative anesthesia techniques are also discussed, including their possible advantages, disadvantages, indications, and counterindications.

Pharmacokinetics of S(+) ketamine derived from target controlled infusion

BACKGROUND

A computer controlled infusion device for S(+) ketamine was used in combination with a Diprifusor device to provide anaesthesia for 20 ASA I or II patients undergoing elective colonoscopy. The aim of the study was to assess the performance of the pharmacokinetic model for S(+) ketamine used in the delivery algorithm of the device.

RESULTS

It was observed that during the first 30 min of infusion there was systematic underprediction by the delivery system of the measured levels of S(+) ketamine. New pharmacokinetic constants were derived from the observed data which provided, on pharmacokinetic simulation, improved prediction of the measured values of S(+) ketamine. Prospective application of this modified model for S(+) ketamine in a further nine study patients was performed and the pharmacokinetic performance of the model was reassessed. The data from all 29 patients was subsequently used to calculate the population distribution of S(+) ketamine clearance. The distribution was found to be normal only in the logarithmic domain. In the normal domain the mode of S(+) ketamine clearance was found to be 35.8 ml kg(-1) min(-1) with 5 and 95% confidence limits of, respectively, 11.5 and 111.1 ml kg(-1) min(-1).

CONCLUSION

It was necessary to modify the original published pharmacokinetic parameters incorporated into the S(+) ketamine delivery system in order to simulate improved PK performance during short procedures (<1 h duration) where propofol was concurrently administered. This improved performance was confirmed in a further prospective study.

The changing role of non-opioid analgesic techniques in the management of postoperative pain

Given the expanding role of ambulatory surgery and the need to facilitate an earlier hospital discharge, improving postoperative pain control has become an increasingly important issue for all anesthesiologists. As a result of the shift from inpatient to outpatient surgery, the use of IV patient-controlled analgesia and continuous epidural infusions has steadily declined. To manage the pain associated with increasingly complex surgical procedures on an ambulatory or short-stay basis, anesthesiologists and surgeons should prescribe multimodal analgesic regimens that use non-opioid analgesics (e.g., local anesthetics, nonsteroidal antiinflammatory drugs, cyclooxygenase inhibitors, acetaminophen, ketamine, alpha 2-agonists) to supplement opioid analgesics. The opioid-sparing effects of these compounds may lead to reduced nausea, vomiting, constipation, urinary retention, respiratory depression and sedation. Therefore, use of non-opioid analgesic techniques can lead to an improved quality of recovery for surgical patients.

Comparison of propofol with propofol-ketamine combination in pediatric patients undergoing auditory brainstem response testing

OBJECTIVE

The aim of our study was to compare propofol with propofol-ketamine combination for sedation and also to compare related complications in children undergoing auditory brainstem response (ABR) testing.

METHODS

Sixty ASA I-II patients aged between 1 and 13 years of age were sedated for ABR testing. Propofol 1.5mg/kg was used in group P (n=30), and ketamine 0.5 mg/kg+propofol 1.5 mg/kg, i.v., in group PK (n=30). Sedation levels of patients were maintained between scores 3 and 4 according to Ramsey sedation scores; when necessary, half of the starting drug dosage was administered for the maintenance of sedation. Side effects which occurred during or within the first 24h of the procedure were assessed.

RESULTS

Additional dosage was needed for 21 cases in group P and eight cases in group PK (p=0.002). While oxygen desaturation and apnea were not observed in any of the patients in group PK, there were four patients (11.4%) with oxygen desaturation, and six (17.1%) with apnea in group P (p<0.05).

CONCLUSIONS

In pediatric cases where ABR testing was applied, addition of low dose ketamine to propofol avoided the risk of respiratory depression due to propofol and lowered the need for additional dose of propofol. Therefore, the co-administration of propofol and ketamine appears to be a safe and useful technique for ABR testing.

Kétamine à faibles doses : antihyperalgésique, non analgésique

Recent data in animal experiments as in clinical trials have clearly reported that pain modulation is related to an equilibrium between antinociceptive and pronociceptive systems. Therefore, the apparent pain level could not only be a consequence of a nociceptive input increase but could also result from a pain sensitization process. Glutamate, via NMDA receptors, plays a major role in the development of such a neuronal plasticity in the central nervous system, leading to a pain hypersensitivity that could facilitate chronic pain development. By an action on NMDA receptors opioids also induce, in a dose dependent manner, an enhancement of this postoperative hypersensitivity. "Antihyperalgesic" doses of ketamine, an NMDA receptor antagonist, were able to decrease this central sensitization not only in painful animal but also in human volunteers exposed to different pain models, or in the postoperative period. Many studies have reported that ketamine effects are elicited when this drug is administered the following manner: peroperative bolus (0.1 to 0.5 mg/kg), followed by a constant infusion rate (1 to 2 microg/kg per min) during the peroperative period and for 48 to 72 hours after anaesthesia. Those ketamine doses improved postoperative pain management by reducing hyperalgesia due to both surgical trauma and high peroperative opioid doses. This antihyperalgesic action of ketamine also limited the postoperative morphine tolerance leading to a decrease in analgesic consumption and an increase in the analgesia quality.

Propofol and propofol-ketamine in pediatric patients undergoing cardiac catheterization

We investigated the effects of propofol and propofol-ketamine on hemodynamics, sedation level, and recovery period in pediatric patients undergoing cardiac catheterization. We performed a prospective, randomized, double-blind study. The study included 60 American Society of Anesthesiologists physical status II or III (age range, 1 month-13 years) undergoing cardiac catheterization for evaluation of congenital heart disease. Propofol and ketamine were prepared in 5% glucose solution to a final concentration of 5 and 1 mg/ml, respectively; similar injectors containing 5% glucose solution only were prepared. Fentanyl (1 microg/kg) and propofol (1.5 mg/kg) were given to both groups. Then, group 1 received 0.5 ml/kg of 5% glucose and group 2 0.5 ml/kg of ketamine solution by an anesthesiologist who was unaware of the groups of patients. Local anesthesia with 1% lidocaine was administered before intervention in all patients. The noninvasively measured mean arterial pressure, heart rate, respiratory rate, and peripheral oxygen saturation were recorded at the baseline, following drug administration, at 3, 5, 10, 15, 20, and 30 minutes and then at 15-minute intervals until the end of the procedure. Additional drug and fentanyl requirements to maintain a sedation level of 4 or 5 were recorded. After the procedure, the time to a Steward recovery score of 6 and adverse effects in the first 24 hours were recorded. The number of patients with more than a 20% decrease in mean arterial pressure was 11 in group 1 and 3 in group 2 (p < 0.05). The number of patients who experienced more than a 20% decrease in heart rate was 12 in group 1 and 5 in group 2 (p = 0.054). Ten patients in group 1 and 3 patients in group 2 required additional fentanyl doses (p = 0.057). The number of additional propofol doses was lower in group 2 (p < 0.05). Propofol combined with low-dose ketamine preserves mean arterial pressure better without affecting the recovery and thus is a good option in pediatric patients undergoing cardiac catheterization.

Effects of low dose ketamine before induction on propofol anesthesia for pediatric magnetic resonance imaging

BACKGROUND

We aimed to investigate effects of low dose ketamine before induction on propofol anesthesia for children undergoing magnetic resonance imaging (MRI).

METHODS

Forty-three children aged 9 days to 7 years, undergoing elective MRI were randomly assigned to receive intravenously either a 2.5 mg x kg(-1) bolus of propofol followed by an infusion of 100 microg x g(-1) x min(-1) or a 1.5 mg x kg(-1) bolus of propofol immediately after a 0.5 mg x kg(-1) bolus of ketamine followed by an infusion of 75 microg x kg(-1) x min(-1). If a child moved during the imaging sequence, a 0.5-1 mg x kg(-1) bolus of propofol was given. Systolic and diastolic blood pressures, heart rate, peripheral oxygen saturation and respiratory rates were monitored. Apnea, the requirement for airway opening maneuvers, secretions, nausea, vomiting and movement during the imaging sequence were noted. Recovery times were also recorded.

RESULTS

Systolic blood pressure and heart rate decreased significantly in the propofol group, while blood pressure did not change and heart rate decreased less in the propofol-ketamine group. Apnea associated with desaturation was observed in three patients of the propofol group. The two groups were similar with respect to requirements for airway opening maneuvers, secretions, nausea-vomiting, movement during the imaging sequence and recovery time.

CONCLUSIONS

Intravenous administration of low dose ketamine before induction and maintenance with propofol preserves hemodynamic stability without changing the duration and the quality of recovery compared with propofol alone.

Modified tumescent technique for outpatient facial laser resurfacing

PURPOSE

The study goal was to retrospectively review the effectiveness of a modified tumescent technique to provide anesthesia for facial laser resurfacing in an office-based setting.

PATIENTS AND METHODS

The charts of 54 consecutive patients treated with facial laser resurfacing at a large outpatient clinic were retrospectively reviewed for type of intravenous sedation/analgesia, adequacy of anesthesia, complications, and discharge criteria. All patients were treated with a modified tumescent technique with or without intravenous sedation.

RESULTS

All patients tolerated the procedure extremely well. There were no anesthesia-related complications regarding loss of airway/airway obstruction, desaturation, or prolonged recovery periods. Several patients tolerated the procedure comfortably without intravenous sedation/analgesia.

CONCLUSIONS

The modified tumescent technique is a valuable method to provide patient comfort during facial laser resurfacing while reducing the risk for anesthesia-related complications.

A Qualitative Systematic Review of the Role of N-Methyl-d-Aspartate Receptor Antagonists in Preventive Analgesia

We evaluated in a qualitative systematic review the effect of N-methyl-D-aspartate (NMDA) receptor antagonists on reducing postoperative pain and analgesic consumption beyond the clinical duration of action of the target drug (preventive analgesia). Randomized trials examining the use of an NMDA antagonist in the perioperative period were sought by using a MEDLINE (1966-2003) and EMBASE (1985-2003) search. Reference sections of relevant articles were reviewed, and additional articles were obtained if they evaluated postoperative analgesia after the administration of NMDA antagonists. The primary outcome was a reduction in pain, analgesic consumption, or both in a time period beyond five half-lives of the drug under examination. Secondary outcomes included time to first analgesic request and adverse effects. Forty articles met the inclusion criteria (24 ketamine, 12 dextromethorphan, and 4 magnesium). The evidence in favor of preventive analgesia was strongest in the case of dextromethorphan and ketamine, with 67% and 58%, respectively, of studies demonstrating a reduction in pain, analgesic consumption, or both beyond the clinical duration of action of the drug concerned. None of the four studies examining magnesium demonstrated preventive analgesia.

IMPLICATIONS

We evaluated, in a qualitative systematic review, the effect of N-methyl D-aspartate antagonists on reducing postoperative pain and analgesic consumption beyond the clinical duration of action of the target drug (preventive analgesia). Dextromethorphan and ketamine were found to have significant immediate and preventive analgesic benefit in 67% and 58% of studies, respectively.

Effect of variable-dose propofol alone and in combination with two fixed doses of ketamine for total intravenous anesthesia in cats

OBJECTIVE

To determine the minimum infusion rate (MIR50) for propofol alone and in combination with ketamine required to attenuate reflexes commonly used in the assessment of anesthetic depth in cats.

ANIMALS

6 cats.

PROCEDURE

Propofol infusion started at 0.05 to 0.1 mg/kg/min for propofol alone or 0.025 mg/kg/min for propofol and ketamine (low-dose ILD] constant rate infusion [CRI] of 23 microg/kg/min or high-dose [HD] CRI of 46 microg/kg/min), and after 15 minutes, responses of different reflexes were tested. Following a response, the propofol dose was increased by 0.05 mg/kg/min for propofol alone or 0.025 mg/kg/min for propofol and ketamine, and after 15 minutes, reflexes were retested.

RESULTS

The MIR50 for propofol alone required to attenuate blinking in response to touching the medial canthus or eyelashes; swallowing in response to placement of a finger or laryngoscope in the pharynx; and to toe pinch, tetanus, and tail-clamp stimuli were determined. Addition of LD ketamine to propofol significantly decreased MIR50, compared with propofol alone, for medial canthus, eyelash, finger, toe pinch, and tetanus stimuli but did not change those for laryngoscope or tail-clamp stimuli. Addition of HD ketamine to propofol significantly decreased MIR50, compared with propofol alone, for medial canthus, eyelash, toe pinch, tetanus, and tail-clamp stimuli but did not change finger or laryngoscope responses.

CONCLUSIONS AND CLINICAL RELEVANCE

Propofol alone or combined with ketamine may be used for total IV anesthesia in healthy cats at the infusion rates determined in this study for attenuation of specific reflex activity.

The general anesthetic propofol increases brain N-arachidonylethanolamine (anandamide) content and inhibits fatty acid amide hydrolase

1. Propofol (2,6-diisopropylphenol) is widely used as a general anesthetic and for the maintenance of long-term sedation. We have tested the hypothesis that propofol alters endocannabinoid brain content and that this effect contributes to its sedative properties. 2. A sedating dose of propofol in mice produced a significant increase in the whole-brain content of the endocannabinoid, N-arachidonylethanolamine (anandamide), when administered intraperitoneally in either Intralipid or emulphor-ethanol vehicles. 3. In vitro, propofol is a competitive inhibitor (IC(50) 52 micro M; 95% confidence interval 31, 87) of fatty acid amide hydrolase (FAAH), which catalyzes the degradation of anandamide. Within a series of propofol analogs, the critical structural determinants of FAAH inhibition and sedation were found to overlap. Other intravenous general anesthetics, including midazolam, ketamine, etomidate, and thiopental, do not affect FAAH activity at sedative-relevant concentrations. Thiopental, however, is a noncompetitive inhibitor of FAAH at a concentration of 2 mM. 4. Pretreatment of mice with the CB(1) receptor antagonist SR141716 (1 mg kg(-1), i.p.) significantly reduced the number of mice that lost their righting reflex in response to propofol. Pretreatment of mice with the CB(1) receptor agonist, Win 55212-2 (1 mg kg(-1), i.p.), significantly potentiated the loss of righting reflex produced by propofol. These data indicate that CB(1) receptor activity contributes to the sedative properties of propofol. 5. These data suggest that propofol activation of the endocannabinoid system, possibly via inhibition of anandamide catabolism, contributes to the sedative properties of propofol and that FAAH could be a novel target for anesthetic development.

Cardiovascular effects of propofol alone and in combination with ketamine for total intravenous anesthesia in cats

OBJECTIVE

To compare cardiovascular effects of equipotent infusion doses of propofol alone and in combination with ketamine administered with and without noxious stimulation in cats.

ANIMALS

6 cats.

PROCEDURE

Cats were anesthetized with propofol (loading dose, 6.6 mg/kg; constant rate infusion [CRI], 0.22 mg/kg/min) and instrumented for blood collection and measurement of blood pressures and cardiac output. Cats were maintained at this CRI for a further 60 minutes, and blood samples and measurements were taken. A noxious stimulus was applied for 5 minutes, and blood samples and measurements were obtained. Propofol concentration was decreased to 0.14 mg/kg/min, and ketamine (loading dose, 2 mg/kg; CRI, 23 microg/kg/min) was administered. After a further 60 minutes, blood samples and measurements were taken. A second 5-minute noxious stimulus was applied, and blood samples and measurements were obtained.

RESULTS

Mean arterial pressure, central venous pressure, pulmonary arterial occlusion pressure, stroke index, cardiac index, systemic vascular resistance index, pulmonary vascular resistance index, oxygen delivery index, oxygen consumption index, oxygen utilization ratio, partial pressure of oxygen in mixed venous blood, pH of arterial blood, PaCO2, arterial bicarbonate concentration, and base deficit values collected during propofol were not changed by the addition of ketamine and reduction of propofol. Compared with propofol, ketamine and reduction of propofol significantly increased mean pulmonary arterial pressure and venous admixture and significantly decreased PaO2.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of propofol by CRI for maintenance of anesthesia induced stable hemodynamics and could prove to be clinically useful in cats.

Intravenous techniques in ambulatory anesthesia

The growing importance of ambulatory surgery during the past decade has led to the development of efficient anesthetic techniques in terms of quality and safety of anesthesia and recovery. In these challenging objectives, intravenous techniques have played an important role, as they provide safe, efficient, and cost-effective anesthesia in the ambulatory setting. Among the numerous intravenous drugs, propofol, with its fast and smooth onset of action, short duration of action, and low incidence of postoperative side effects appears to be the anesthetic of choice in this situation. The recent development of new techniques of administration (such as TCI, monitored anesthesia care, or patient-controlled sedation) and monitoring (such as the BIS and the availability of "hit and run" drugs such as remifentanil) will optimize intraoperative conditions and recovery, thus allowing faster home readiness in the ambulatory setting.

Dexmedetomidine and low-dose ketamine provide adequate sedation for awake fibreoptic intubation

PURPOSE

We report the use of the alpha2 agonist, dexmedetomidine, with low-dose ketamine as a safe and effective treatment strategy to provide adequate comfort and sedation for a patient who fulfilled criteria of a difficult airway and required awake fibreoptic intubation (AFOI).

CLINICAL FEATURES

A 52-yr-old male with prostate cancer presented for radical prostatectomy. He reported several failed intubations with previous surgeries and airway examination was consistent with a difficult intubation. In addition, previous fibreoptic intubations were unsuccessful. The patient reported extreme apprehension concerning his airway management. The goal of medicating patients for AFOI includes providing comfort and sedation without causing a change in ventilatory status. Dexmedetomidine has a high affinity for the alpha2 receptor and results in sedation without change in ventilatory status. In addition, dexmedetomidine is a potent anti-sialgogue which makes it desirable for cases involved with airway instrumentation. A loading dose of dexmedetomidine followed by a continuous infusion provided comfort and sedation within ten minutes. While bradycardia and hypotension have been reported with dexmedetomidine use, concurrent low-dose ketamine was employed in this case for it's cardiostimulatory properties and no bradycardia and hypotension were noted. The airway was anesthetized with selective nerve blocks and conditions for airway instrumentation were excellent. There was no change in oxygen saturation or ventilatory status during the administration of medications or airway manipulation. The patient was comfortable, sedated and tolerated the procedures well. There was no recall of the procedure.

CONCLUSION

Dexmedetomidine and concurrent low-dose ketamine provided sedation and comfort to this patient who required an AFOI.

Non-opioid analgesia improves pain relief and decreases sedation after gastric bypass surgery

PURPOSE

Several non-opioid drugs have been shown to provide analgesia during and after surgery. We compared sevoflurane anesthesia with fentanyl analgesia to sevoflurane and non-opioid drug treatment for gastric bypass surgery and recovery.

METHODS

Thirty obese patients (body mass index > 50 kg.m(-2)) undergoing gastric bypass were randomized to receive sevoflurane anesthesia with either fentanyl or a non-opioid regimen including ketorolac, clonidine, lidocaine, ketamine, magnesium sulfate, and methylprednisolone. Morphine use by patient-controlled analgesia (PCA) pump and pain score measured by visual analogue scale were determined in the postanesthesia care unit (PACU) and for the first 16 hr after surgery. Sedation was evaluated in the PACU. Investigators assessing patient outcomes were blinded to the study group.

RESULTS

Fentanyl treated patients were more sedated in the PACU compared to the non-opioid group. Non-opioid treated patients required 5.2 +/- 2.6 mg.hr(-1) morphine by PCA during their stay in the PACU while patients anesthetized with fentanyl used 7.8 +/- 3.3 mg.hr(-1) (P < 0.05). Fentanyl and non-opioid treated patients showed no difference in pain score one or 16 hr after surgery.

CONCLUSION

Our results show that non-opioid analgesia produced pain relief and less sedation during recovery from gastric bypass surgery compared to fentanyl.

Modulation of remifentanil-induced analgesia, hyperalgesia, and tolerance by small-dose ketamine in humans

Adding a small dose of ketamine to opioids may increase the analgesic effect and prevent opioid-induced hyperalgesia and acute tolerance to opioids. In this randomized, double-blinded, placebo-controlled crossover study, we investigated the effect of remifentanil combined with small concentrations of ketamine on different experimental pain models. Pain detection thresholds to single and repeated IM electrical stimulation and to repeated transcutaneous electrical stimulation, pressure pain tolerance threshold, and sedative, respiratory, and cardiovascular side effects were assessed in 14 healthy volunteers. Saline, remifentanil alone, and remifentanil combined with ketamine at target plasma concentrations of 50 or 100 ng/mL were administered in four study sessions. The ketamine infusion was started after baseline testing at a constant target concentration. Remifentanil was started after testing with ketamine alone at an initial target concentration of 1 ng/mL and then increased to 2 ng/mL and decreased to 1 ng/mL. The last test series were started 10 min after discontinuation of remifentanil. Acute remifentanil-induced hyperalgesia and tolerance were detected only by the pressure pain test and were not suppressed by ketamine. Remifentanil alone induced significant analgesia with all pain tests. Ketamine further increased the remifentanil effect only on IM electrical pain. Remifentanil at a 2 ng/mL target concentration induced a slight respiratory depression that was antagonized by ketamine. We conclude that ketamine effects on opioid analgesia are pain-modality specific.

IMPLICATIONS

Coadministration of ketamine and morphine for pain relief is still controversial. Our experimental pain study with volunteers showed that ketamine enhances opioid analgesia without increasing sedation and reduces respiratory depression. Opioid-induced hyperalgesia and tolerance were not affected by ketamine and depended on the type of nociceptive stimulus. This may explain the conflicting results on opioid tolerance in previous studies.

Fast-tracking in outpatient surgery

Fast-tracking in outpatient surgery is a new paradigm that allows for rapid throughput and early discharge, thereby facilitating perioperative efficiency. Compared with the conventional recovery process, bypassing the postanesthesia care unit reduces the time to discharge home. An ideal anesthetic technique for fast-tracking would provide for rapid emergence and the prevention of common postoperative complications such as pain, nausea, and vomiting using a multimodal approach.