Patient-maintained propofol sedation: a follow up safety study using a modified system in volunteers

Patient-maintained propofol sedation for adult patients undergoing surgical or medical procedures: a scoping review of current evidence and technology

Patient-maintained propofol sedation (PMPS) is the delivery of procedural propofol sedation by target-controlled infusion with the patient exerting an element of control over their target-site propofol concentration. This scoping review aims to establish the extent and nature of current knowledge regarding PMPS from both a clinical and technological perspective, thereby identifying knowledge gaps to guide future research. We searched MEDLINE, EMBASE, and OpenGrey databases, identifying 17 clinical studies for analysis. PMPS is described in the context of healthy volunteers and in orthopaedic, general surgical, dental, and endoscopic clinical settings. All studies used modifications to existing commercially-available infusion devices to achieve prototype systems capable of PMPS. The current literature precludes rigorous generalisable conclusions regarding the safety or comparative clinical effectiveness of PMPS, however cautious acknowledgement of efficacy in specific clinical settings is appropriate. Based on the existing literature, together with new standardised outcome reporting recommendations for sedation research and frameworks designed to assess novel health technologies research, we have made recommendations for future pharmacological, clinical, behavioural, and health economic research on PMPS. We conclude that high-quality experimental clinical trials with relevant comparator groups assessing the impact of PMPS on standardised patient-orientated outcome measures are urgently required.

Efficacy and safety of propofol in preventing emergence agitation after sevoflurane anesthesia for children

Application of propofol in preventing emergence agitation after sevoflurane anesthesia in children was evaluated. Clinical data of 200 children who received sevoflurane anesthesia in Children's Hospital of Xuzhou Medical University were retrospectively analyzed. Among them, 120 patients who received inhaled sevoflurane for pediatric anesthesia and intravenous infusion of propofol (2 mg/kg) were included in observation group. The remaining 80 cases who were directly anesthetized by sevoflurane alone were the control group. T PAED scores, modified Aldrete scores, extubation time, PACU time and adverse reactions (gastrointestinal tract and respiratory response) were analyzed and compared between the control and observation group. PAED scores, extubation time, PACU time and incidence of adverse reactions were significantly lower in observation than in control group, and the modified Aldrete scores were higher in observation than in control group (P<0.05). Spearman's correlation analysis showed that the PAED scores were negatively correlated with modified Aldrete scores and positively correlated with extubation time. There was positive correlation between the PACU time and incidence of adverse reactions and between the PAED scores and extubation time. There was negative correlation between PACU time and incidence of adverse reactions and between Aldrete scores and extubation time (P<0.05). Therefore, we conclude that propofol can be used to prevent agitation after sevoflurane anesthesia in children.

Assessment of different anesthesia depth under total intravenous anesthesia on postoperative cognitive function in laparoscopic patients

Background:

This study aimed to compare the effects of different depths of sedation during total intravenous anesthesia (TIVA) with remifentanil and propofol given by target-controlled infusion (TCI) on postoperative cognitive function in young and middle-aged patients undergoing gynecological laparoscopic surgery.

Materials and Methods:

A total of 150 American Society of Anesthesiologists physical Status I/II patients scheduled for gynecological laparoscopic operation were randomly divided into three groups. Anesthesia was maintained with intravenous infusion of TCI propofol and remifentanil, intermittent injected intravenously with rocuronium. The infusion concentration of propofol and remifentanil was adjusted to maintain bispectral index (BIS) at 30 < BIS ≤ 40 in the first group, 40 < BIS ≤ 50 in the second group, and 50 < BIS ≤ 60 in the third group. Mini–mental state examination (MMSE) and trail-making test (TMT) were used to assess the cognitive function one day preoperatively and one day postoperatively.

Results:

MMSE scores were > 24 sores on the day before anesthesia and the day after surgery in all three groups. However, the first group had the significantly higher MMSE scores than the other two groups after surgery (P < 0.05). Compared with that before anesthesia, TMT completion time was shorter on the day after surgery in the first group, while prolonged in the third group (P < 0.05). The first group had the significantly lower TMT completion time than the other two groups (P < 0.05).

Conclusion:

The depth of sedation, 30 < BIS value ≤ 40, under TIVA with remifentanil and propofol given by TCI had the minimal influence on postoperative cognitive function.

Effect of different depths of anesthesia on postoperative cognitive function in laparoscopic patients: a randomized clinical trial

OBJECTIVE

Postoperative cognitive dysfunction (POCD) is caused by many factors. This work was conducted to investigate the effect of different depths of anesthesia during combined intravenous-inhalational anesthesia on postoperative cognitive function in young and middle-aged laparoscopic patients.

METHODS

A total of 192 patients scheduled for gynecologic laparoscopic operations were randomly divided into three groups. Anesthesia was maintained with inhalation of sevoflurane and infusion of remifentanil, which was adjusted to maintain bispectral index (BIS) at 30 < BIS ≤ 40 in Group I, 40 < BIS ≤ 50 in Group II and 50 < BIS ≤ 60 in Group III. The Mini-Mental State Examination (MMSE) and Trail-Making Test (TMT) were used to assess cognitive function on the day before anesthesia and the day after surgery.

RESULTS

There were no significant differences in age, body mass index, educational level and surgery time. On the day before anesthesia, the average MMSE scores and TMT completion times in the three groups were not significantly different. On the day after surgery, Group II had a significantly higher average MMSE score (29.00 ± 0.89) than Group I (28.36 ± 1.42, p = 0.010) and Group III (28.45 ± 1.27, p = 0.035) and lower TMT completion time (33.68 ± 10.34) than Group I (39.45 ± 13.99, p = 0.027) and Group III (39.50 ± 12.50, p = 0.026).

CONCLUSION

These results indicated that the depth of anesthesia, 40 < BIS ≤ 50, under combined intravenous-inhalational anesthesia yielded milder influence on postoperative cognitive function in young and middle-aged laparoscopic patients.

Reaction time-monitored patient-maintained propofol sedation: a pilot study in oral surgery patients

Previous volunteer studies of an effect-site controlled patient-maintained sedation system using propofol have demonstrated a risk of oversedation. We have incorporated a reaction time monitor into the handset to add an individualised patient-feedback mechanism. This pilot study assessed if the reaction time-feedback modification would prove safe and effective in 20 healthy patients receiving sedation while undergoing oral surgery. All patients successfully sedated themselves without reaching any unsafe endpoints. All 20 maintained verbal contact throughout. The mean (SD) lowest peripheral blood oxygen saturation was 98.0 (2.1)% breathing room air. No patient required supplementary oxygen. The mean (SD) maximum effect-site propofol concentration reached was 1.6 (0.5) μg.ml(-1). The present system was found to be safe and effective, allowing oral surgery treatment under conscious sedation, but preventing oversedation.

Patient-maintained propofol sedation using reaction time monitoring: a volunteer safety study

Previous volunteer studies of an effect-site controlled, patient-maintained sedation system using propofol have demonstrated a risk of over-sedation. We have incorporated a reaction-time monitor into the handset of the patient-maintained sedation system to add an individualised patient-feedback mechanism. This study assessed if such reaction-time feedback modification would reduce the risk of over-sedation in 20 healthy volunteers deliberately attempting to over-administer themselves propofol. All the volunteers successfully sedated themselves without reaching any unsafe endpoints. All volunteers maintained verbal contact throughout, in accordance with the definition of conscious sedation. The mean (SD) lowest S(p) O(2) was 97 (1.7) % when breathing room air and no volunteer required supplementary oxygen. The mean (SD) maximum effect-site propofol concentration reached was 1.7 (0.4) μg.ml(-1) . The present system was found to be safer than its predecessors, allowing conscious sedation, but preventing over-sedation.

Dissociating speech perception and comprehension at reduced levels of awareness

We used functional MRI and the anesthetic agent propofol to assess the relationship among neural responses to speech, successful comprehension, and conscious awareness. Volunteers were scanned while listening to sentences containing ambiguous words, matched sentences without ambiguous words, and signal-correlated noise (SCN). During three scanning sessions, participants were nonsedated (awake), lightly sedated (a slowed response to conversation), and deeply sedated (no conversational response, rousable by loud command). Bilateral temporal-lobe responses for sentences compared with signal-correlated noise were observed at all three levels of sedation, although prefrontal and premotor responses to speech were absent at the deepest level of sedation. Additional inferior frontal and posterior temporal responses to ambiguous sentences provide a neural correlate of semantic processes critical for comprehending sentences containing ambiguous words. However, this additional response was absent during light sedation, suggesting a marked impairment of sentence comprehension. A significant decline in postscan recognition memory for sentences also suggests that sedation impaired encoding of sentences into memory, with left inferior frontal and temporal lobe responses during light sedation predicting subsequent recognition memory. These findings suggest a graded degradation of cognitive function in response to sedation such that "higher-level" semantic and mnemonic processes can be impaired at relatively low levels of sedation, whereas perceptual processing of speech remains resilient even during deep sedation. These results have important implications for understanding the relationship between speech comprehension and awareness in the healthy brain in patients receiving sedation and in patients with disorders of consciousness.

A review of the use of propofol for procedural sedation in the emergency department

Sedation for short but potentially painful procedures is often undertaken in the emergency department. The ideal sedative regimen should provide analgesia and anxiolysis with minimal side effects and cardiorespiratory depression and rapid recovery post-procedure. Propofol has found increasing popularity with anaesthetists for sedation in the operating theatre. This is a review of the current literature looking at the use of propofol for procedural sedation in the emergency department. A comprehensive literature search of Medline from 1966 to week 4 of 2005, Embase from 1980 to week 10 of 2005, and the Cochrane Library was carried out using the OVID interface. Eight articles were selected for review. The evidence suggests that propofol is both effective and safe to use in the emergency department. However, several of the papers reviewed used deep levels of sedation that are not recommended in the UK by non-anaesthetists.

Recent developments in patient-controlled analgesia

Patient-controlled analgesia (PCA) has become the gold standard for acute pain management since it was first introduced 20 years ago, and its merits have been discussed in quite a large number of publications. This review summarizes the more recent developments, such as new application devices and strategies, including intranasal, spinal, and regional PCA; patient-controlled sedation; experience with children and elderly people; and some data from chronic pain situations. Analyzing PCA literature from 2001 onwards confirms the author's long belief that the PCA principle ("WYNIWYG": what you need is what you get) was the most important aspect of a patient-controlled strategy, more or less independent of the type of drug or machine. Discovering this principle has changed the understanding of pain and suffering.

Effect-site controlled patient maintained propofol sedation: a volunteer safety study

Effect-site concentration is a mathematical term related to the clinical effect of a drug. We have designed a patient-maintained sedation system for delivering propofol to the predicted effect-site concentration rather than plasma concentration. To assess its efficacy and safety, 20 healthy volunteers deliberately attempted to over-sedate themselves using the system. The new effect-site concentration driven system delivered sedation successfully, and more rapidly than its predecessor. Fifteen volunteers ended the study when the system automatically reduced the effect-site concentration after 6 min of no button presses despite verbal contact and maintenance of arterial oxygen saturation (at effect-site concentration 1.8-3.8 microg x ml(-1)). Four out of 20 volunteers ended with minor arterial desaturation (lowest 88% at effect-site concentration 2.6-3.4 microg x ml(-1)). One volunteer ended after loss of verbal contact at effect-site concentration 3.4 microg x ml(-1). Further modification of the system's design is necessary before it can be recommended for routine practice.

Patient-controlled sedation using propofol for dressing changes in burn patients: a dose-finding study

The first change of dressings after skin grafting in burn patients is a source of great anxiety because of pain anticipation and the immediate and first confrontation with the result of skin grafting. We designed this dose-finding study to determine the feasibility and safety of patient-controlled sedation (PCS) using propofol during these procedures. Twenty patients were familiarized with the PCS and asked to use PCS whenever they felt uncomfortable or anxious. Analgesia was provided by a single bolus of morphine IV 15 min before the procedure according to their daily intake. The first 10 patients used a fixed bolus of propofol 0.3 mg/kg and a lockout of 5 min. The degree of sedation was measured using bispectral index (BIS) monitoring. Demands versus delivery of propofol boluses were recorded. Within 1 h after the procedure, pain intensity was evaluated and satisfaction scores obtained from patients and nurses performing the dressing changes. In the first 10 patients, there were no respiratory rates <10 breaths/min, systolic and diastolic blood pressure were within 25% of baseline values, and peripheral saturation stayed more than 94% with additional small flow oxygen via nasal insufflation. There were double the demands than actual deliveries of propofol boluses. The BIS did not show significant decreases of <80 in any patient reflecting an insufficient state of sedation. Because the interim analysis of the efficacy of the PCS setup showed an insufficient state of sedation, a different PCS setup was evaluated in a second group of 10 patients (an individualized propofol bolus, titrated to achieve a significant decrease of BIS or a sleepy state, and no lockout period). The second group of patients showed a more effective sedation, with respiratory and hemodynamic variables being not significantly different from the first group of patients. PCS with propofol is feasible in burn patients and can be used safely. To provide an optimal sedation, we suggest to initially titrate the bolus to achieve a significant decrease of BIS or a clinically effective state of sedation and to abolish the lockout interval.

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.

Propofol target-controlled infusions for sedation--a safe technique for the non-anaesthetist?

OBJECTIVE

As an alternative to general anaesthesia for dentistry.attention has been focused on other, apparently safer, methods of pain and anxiety control. We have undertaken a study to evaluate the safety and efficacy of intravenous sedation using propofol target-controlled infusions.

DESIGN

We describe a retrospective observational analysis of propofol conscious sedation as an adjunct to local anaesthesia for patients undergoing simple or surgical exodontia. All the patients were assessed,selected and treated according to standardized hospital sedation protocols. Experienced anaesthetists used a standard regimen, with ECG, pulse oximetry and non-invasive blood pressure monitoring. A standard sedation record was completed for each patient. The initial target plasma propofol concentration was set at 1.5 microg ml(-1), adjusted thereafter to achieve the desired level of sedation. Any adverse events were recorded.

SETTING

Birmingham Dental Hospital.

SUBJECTS

Three hundred consecutive sedation episodes in adult dental phobic patients requiring exodontia under local anaesthesia.

RESULTS

Sedation and treatment were satisfactorily completed in 297 patients. The mean target propofol concentration required was 2.1 microg ml(-1), (SD = 0.47 microg ml(-1), range 1 - 4 microg ml(-1)). General anaesthesia occurred in two cases (target concentration (TC) 2 microg ml(-1)), over sedation in 11 cases(TC 1 - 3 microg ml(-1)), and transient hypoxaemia in 7 cases (TC 1.8 - 2.5 microg ml(-1)).

CONCLUSION

Intravenous sedation with target-controlled propofol infusions is effective. However, significant adverse effects may occur at target concentrations below 2.1 microg ml(-1). Only anaesthetists working in an appropriate environment should practise this technique.