Gavin N.C. Kenny

Gavin N.C. Kenny
The University of Hong Kong | HKU · Department of Anaesthesiology

BSc(hons) MB ChB FRCA MD FANZCA

About

263
Publications
45,261
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9,310
Citations
Citations since 2016
3 Research Items
1526 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300

Publications

Publications (263)
Chapter
Sedation helps patients tolerate unpleasant procedures. Sedation has been termed as the process of calming; this involves anxiolysis, amnesia and altered conscious level. The main agents used are midazolam and propofol. Propofol is an excellent sedative due to its pharmacokinetics and dynamics. Its onset is rapid, recovery faster and anxiolysis sup...
Article
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 a...
Article
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 f...
Article
Increasing the calculated plasma concentration of propofol has been shown to increase choice reaction time and visual and auditory response times. We studied the relationship of reaction to a vibrating handset as the effect-site target-controlled propofol concentration was incrementally increased in 20 patients during sedation, before induction of...
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An abstract is unavailable. This article is available as HTML full text and PDF.
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The aim of this study was to compare the accuracy of local anesthetic placement in the rectus sheath block when performed by trainee anesthetists using loss of resistance (LOR) or ultrasound guidance. Eighty-one patients undergoing laparoscopic surgery were randomly assigned to undergo rectus sheath block by either LOR or ultrasound guidance. Train...
Article
A workshop to introduce medical teachers to the use of microcomputers is described. Details are given of the programs demonstrated, which include interactive programs to interview patients, clinical management simulations, educational games and diagnostic simulations and aids. The plenary discussion is reported as an explanation of computer terms a...
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The aim of this study was to compare the efficacy of fascia iliaca block, performed by loss of resistance and ultrasound guidance techniques. Eighty patients undergoing either unilateral hip or knee joint replacement surgery were randomly assigned to undergo fascia iliaca compartment block by either loss of resistance or ultrasound guidance. Sensat...
Article
Background and Objectives:: The aim of this study was to compare the efficacy of fascia iliaca block, performed by loss of resistance and ultrasound guidance techniques. Methods:: Eighty patients undergoing either unilateral hip or knee joint replacement surgery were randomly assigned to undergo fascia iliaca compartment block by either loss of res...
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Background and objective: Attempts to describe the variability of propofol pharmacokinetics in adults and to derive population covariates have been sparse and limited mainly to experiments based on bolus doses or infusions in healthy volunteers. This study aimed to identify age and gender covariates for propofol when given as an infusion in anaest...
Article
An abstract is unavailable. This article is available as HTML full text and PDF.
Article
We have compared the opioid effects of a patient-demand, target-controlled infusion of alfentanil (n = 10), with patient-controlled bolus administration of morphine (n = 10) following major spinal surgery in Chinese patients aged from 11 to 67 years. The same general anaesthesia regimen was used in all patients. One group of patients were given int...
Article
Patients who use on-demand analgesia prefer voice feedback rather than buzzer tones to indicate operation of the apparatus. Twenty-four patients had experience of a patient-controlled analgesia apparatus which incorporated a sophisticated feedback of buzzer tones and a speech synthesiser. Of those who expressed a preference, fifteen preferred the s...
Article
There is a debate regarding whether opioids, as a component of general anesthesia, are adequately reflected in the assessment of anesthesia based on derivatives of the electroencephalogram. To test the hypothesis of a possible quantitative contribution of remifentanil on middle latency auditory evoked potentials, we studied its interaction with pro...
Article
We have designed a new effect-site controlled, patient-maintained sedation system for delivering propofol. In the previous systems we developed, the patients retained the use of the handset throughout the procedure and were able to increase the level of sedation. However, it was found that this could potentially lead to oversedation. In the present...
Article
An anaesthesia control system and a method of calculating an index representative of the depth of anaesthesia is disclosed. The method comprises subjecting a patient to a repetitive audio stimulus and monitoring and auditory evoked potentials (AEP) produced by the patient and then recording these auditory evoked potentials using EEG recording means...
Article
To compare the ability of the aepEX, a derivative of auditory evoked potentials, the bispectral index, and SEF95% to predict responses to various stimuli. Prospective clinical study. General Intensive Care Unit in a university hospital. Forty postsurgical, mechanically ventilated patients. Target concentrations of blood propofol were randomly set a...
Article
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 themselve...
Article
Patient-maintained sedation using propofol has recently been shown to be effective for dental surgery. We compared this new technique to the established technique of operator administered midazolam. The two groups were compared before, during and after sedation. The two primary outcomes were time until discharge and oxygen saturation. Vital signs,...
Article
In this study, we evaluated safety and recovery using a patient maintained, target controlled infusion of propofol for sedation in 20 patients undergoing colonoscopy. Using a handset with a two-minute lockout interval, patients could make 0.2 micro g.ml(-1) increments to an initial target plasma concentration of 1 micro g.ml(-1) up to a maximum 4.5...
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Full-text available
A prototype paediatric propofol target-controlled infusion (TCI) system, the 'Paedfusor' has been developed. This system incorporates a paediatric pharmacokinetic data set and algorithm specific for children in a Graseby 3500 anaesthesia syringe driver. In this study we have evaluated the accuracy of the Paedfusor TCI system in children who underwe...
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Full-text available
Opioid drugs block reflex pupillary dilatation in response to noxious stimulation. The relationship between the target effect site concentration (Ce(T)) of remifentanil and the pupil diameter and reactivity in response to a standard noxious stimulus were evaluated. Anaesthesia was induced with propofol TCI to obtain loss of consciousness (LOC) in 1...
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In this observational study, an alfentanil-containing patient controlled analgesia device was evaluated for the relief of visceral pain during elective caesarean section under subarachnoid anaesthesia. Forty healthy women at term received 2.5 mL of intrathecal hyperbaric 0.5% bupivacaine in the sitting position. Surgery began when loss of cold appr...
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Full-text available
In a previous study we used the bispectral index (BIS) for automatic control of propofol anaesthesia, using a proportional-integral-differential control algorithm. As control was less than optimal in some patients, we revised the constants of the control algorithm. The aim of the current study was to measure the performance of the revised system in...
Article
General anaesthesia is a balance between hypnosis and analgesia. We investigated whether an increase in remifentanil blood concentration would reduce the amount of propofol required to maintain a comparable level of anaesthesia in 60 patients undergoing ambulatory surgery. Patients were allocated randomly to receive remifentanil to a target blood c...
Article
Many anaesthetists are deterred from using total i.v. anaesthesia because of uncertainty over the concentration of propofol required to prevent awareness. We predicted blood and effect-site concentrations of propofol at two clinical end-points: loss of consciousness and no response to a painful stimulus. Forty unpremedicated Caucasian patients were...
Article
To assess the safety and efficacy of a new patient-maintained propofol system for conscious sedation in dentistry. Prospective clinical trial Department of Sedation, Glasgow Dental Hospital and School, 2001 Patients scheduled for oral surgery with conscious sedation. Exclusions included ASA IV -V, inability to use the handset, opioid use and severe...
Chapter
Since one of the earliest systematic observations of the physiologic effects of anaesthetic agents of John Snow in 1847 our interest of measures of the level of anaesthesia has persisted and a variety of approaches and technologies have meanwhile been introduced and utilized. Today, the practice of anaesthesia remains one of the safest and most eff...
Chapter
EEC recording is noninvasive. It is important that the recording electrodes are attached to the scalp carefully in order to limit impedance to the lowest possible level and to obtain the greatest possible EEC wave amplitude. This is usually achieved by sequential application of an abrasive paste and adhesive gel combined with the use of an electrod...
Article
Sixteen patients undergoing colonoscopy were sedated with propofol using a closed-loop control system guided by the Bispectral Index (BIS). Propofol administration, via a target-controlled infusion, was controlled by a proportional-integral-differential control algorithm. The median (range) propofol target concentration during closed-loop control w...
Article
Patient-maintained sedation is a mode of patient-controlled sedation during which propofol is administered using a target-controlled infusion, with patient demand increasing the target concentration. A system tested previously for safety in our institution resulted in oversedation. Aiming to improve safety, we modified the system by increasing the...
Article
Sixty unpremedicated healthy adult patients were studied during induction of anaesthesia with intravenous propofol delivered by a 'Diprifusor' target-controlled infusion. Bispectral index (BIS) and spectral edge frequency (SEF95) were measured concurrently with the predicted blood and effect site propofol concentrations. Logistic regression was use...
Article
Until now, the knowledge of combining anesthetics to obtain an adequate level of anesthesia and to economize wakeup time has been empirical and difficult to represent in quantitative models. Since there is no reason to expect that the effect of non-opioid and opioid anesthetics can be modeled in a simple linear manner, the use of a new computationa...
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Full-text available
The Bispectral Index (BIS) is an electroencephalogram-derived measure of anesthetic depth. A closed-loop anesthesia system was built using BIS as the control variable, a proportional-integral-differential control algorithm, and a propofol target-controlled infusion system as the control actuator. Closed-loop performance was assessed in 10 adult pat...
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Full-text available
Investigators in the field of depth of anaesthesia monitoring sometimes measure the auditory evoked potential (AEP) and the Bispectral Index (BIS) concurrently. However, the auditory stimuli required to generate an AEP may increase the level of consciousness, and cause an increase in the BIS. They may also alter the BIS by producing phase‐locked ha...
Article
The auditory evoked potential (AEP) index, which is a single numerical parameter derived from the AEP in real time and which describes the underlying morphology of the AEP, has been studied as a monitor of anesthetic depth. The current study was designed to evaluate the accuracy of AEPindex for predicting depth of sedation and anesthesia during sev...
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ERCP requires patient cooperation and often prolonged sedation. In different areas of anesthetic practice, patient-controlled sedation with a target-controlled infusion (TCI) of propofol provides effective sedation. The aim of this study was to assess the safety and efficacy of the same system in patients undergoing ERCP. Twenty patients used the T...
Article
Burn dressing changes require profound analgesia for a short duration. This study aimed to determine whether an operator-adjusted target-controlled infusion of alfentanil could provide effective analgesia for burn dressing changes. Ten patients with a burn of between 5 and 50% of body surface area were studied. Pain scoring was performed before, du...
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Intravenous drug administration to provide anaesthesia has evolved in the last decade to become a popular alternative to inhalational anaesthesia. This evolutionary process is a result of improved understanding of pharmacokinetics, pharmacodynamics and the interactions which take place during continuous drug administration. Understanding these proc...
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Full-text available
We studied psychomotor performance in 10 healthy volunteers during recovery after a target‐controlled infusion of propofol. Choice reaction time, dual task tracking with secondary reaction time and a within‐list recognition task were assessed at target blood propofol concentrations of 0.8, 0.4 and 0.2 µg ml–1. Performance was impaired most at the h...
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Full-text available
This study assessed the effect of intravenous alcohol infusions on psychomotor impairment and compared it with that of alcohol administered orally. Comparisons were made between three European drink‐driving limits of blood alcohol concentration (BAC) (20, 50 and 80 mg 100 ml–1) and an oral dose of alcohol 0.75 mg kg–1. Twelve volunteers, aged 22–34...
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Full-text available
We investigated the safety of a patient-maintained system that allows individuals to operate a target-controlled infusion of propofol to achieve sedation. Ten healthy volunteers were recruited and instructed to try to anaesthetize themselves with the system. A target-controlled infusion of propofol was set to deliver a target propofol concentration...
Article
A review of the recent literature reveals an increasing published opinion in favour of unsedated endoscopy. However, recent studies show that the majority of US patients are unwilling or unable to tolerate this. In order for there to be a shift towards unsedated endoscopy, physicians will have to change patients' expectations. The indications for d...
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Full-text available
The target concentration of propofol required to prevent response to surgical incision was determined in 60 unpremedicated ASA I or II patients, who breathed either oxygen-enriched air or nitrous oxide 67% in oxygen. Propofol was infused using a target-controlled infusion system incorporating the standard ‘Diprifusor’ pharmacokinetic model, with th...
Chapter
Closed loop control of anaesthesia (CLAN) offers several benefits to the patient and the anaesthetist. Measurement of the anaesthetic depth variable is automated, so that more frequent measurements are possible, allowing more frequent and more accurate adjustments to the depth of anaesthesia. Thus better control of depth of anaesthesia is possible....
Article
Target-controlled infusions (TCI) aim to provide constant, user-defined blood concentrations of a drug. The infusion device of such a system is controlled by a microprocessor that uses population pharmacokinetic data and the individual patient's weight and age to continuously calculate the required drug infusion rate to replace losses from the bloo...
Article
Remifentanil is a new potent opioid with a very short duration of action irrespective of duration of infusion. It may have a role in day-case anaesthesia as part of a balanced total intravenous anaesthetic technique with propofol. We examined the respiratory depressant effects of remifentanil in 20 patients undergoing day-case anaesthesia. The targ...
Article
Unlabelled: The bispectral index (BIS) of the electroencephalogram and middle latency auditory evoked potentials are likely candidates to measure the level of unconsciousness and, thus, may improve the early recovery profile. We prospectively investigated the predictive performance of both measures to distinguish between the conscious and unconsci...
Article
Unlabelled: Studies in animals and volunteers have suggested the development of acute tolerance to opioid analgesics. In this article, we present data from patients who regulated their own target-controlled infusions of alfentanil and remifentanil to provide analgesia in the immediate postoperative period. Fifty-one patients received alfentanil fo...
Article
Studies in animals and volunteers have suggested the development of acute tolerance to opioid analgesics. In this article, we present data from patients who regulated their own target-controlled infusions of alfentanil and remifentanil to provide analgesia in the immediate postoperative period. Fifty-one patients received alfentanil for 24 h after...
Article
We describe the use of a closed-loop system to control depth of propofol anaesthesia automatically. We used the auditory evoked potential index (AEPindex) as the input signal of this system to validate it as a true measure of depth of anaesthesia. Auditory evoked potentials were acquired and processed in real time to provide the AEPindex. The AEPin...
Article
We describe the use of a closed-loop system to control depth of propofol anaesthesia automatically. We used the auditory evoked potential index (AEP(index)) as the input signal of this system to validate it as a true measure of depth of anaesthesia. Auditory evoked potentials were acquired and processed in real time to provide the AEP(index). The A...
Article
In the past, the discovery of new drugs often occurred by chance. Over recent years, an increasing knowledge of the mode of drug action and receptor sites has improved our ability to design new drugs. While the mode of action of volatile and intravenous anaesthetic agents remains unclear, neuromuscular blocking agents and opioids have undergone con...
Article
We have compared the auditory evoked potential index (AEPIndex) and bispectral index (BIS) for monitoring depth of anaesthesia in spontaneously breathing surgical patients. Twenty patients (aged 17-49 yr) undergoing day surgery were anaesthetized with computer-controlled infusions of propofol. The mean (SD and range) of each measurement was determi...