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O'Brien C, Urquhart CS, Allam S, Anderson KJ, Leitch JA, Macpherson A, Kenny GNC. Reaction time-monitored patient-maintained propofol sedation: a pilot study in oral surgery patients. Anaesthesia 2013; 68:760-4. [PMID: 24044388 DOI: 10.1111/anae.12291] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2013] [Indexed: 11/28/2022]
Abstract
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.
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Affiliation(s)
- C O'Brien
- University of Glasgow Dental School, Glasgow, UK
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Anderson KJ, Allam S, Chapman R, Kenny GNC. The effect of propofol on patient reaction time and its relationship with loss of verbal contact before induction of anaesthesia*. Anaesthesia 2012; 68:148-53. [DOI: 10.1111/anae.12035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Allam S, Anderson KJ, O'Brien C, Macpherson JA, Gambhir S, Leitch JA, Kenny GNC. Patient-maintained propofol sedation using reaction time monitoring: a volunteer safety study. Anaesthesia 2012; 68:154-8. [PMID: 23153106 DOI: 10.1111/anae.12036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
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.
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Affiliation(s)
- S Allam
- Department of Anaesthesia, Forth Valley Royal Hospital, Larbert, UK.
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Dolan J, Kenny GNC, Williams A, Murney E, Smith M. Reply to Dr. Weller. Reg Anesth Pain Med 2009. [DOI: 10.1097/aap.0b013e31819e895b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Chapman RM, Anderson K, Green J, Leitch JA, Gambhir S, Kenny GNC. Evaluation of a new effect-site controlled, patient-maintained sedation system in dental patients. Anaesthesia 2006; 61:345-9. [PMID: 16548953 DOI: 10.1111/j.1365-2044.2006.04544.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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 system, the patients were able to increase their level of sedation until a level was reached that was judged by the patients as being adequate to allow them to tolerate the injection of dental local anaesthetic. The handset was then taken from the patients and the effect site concentration of propofol was maintained at that level for the remainder of the procedure. To assess its safety and efficacy, the system was used to sedate 40 patients presenting for dental procedures under sedation. The system was used successfully and treatment was completed in 39 patients. The system was found to be safe. Both surgeon and patient approval scores were high. Although this study demonstrates the efficacy of effect-site controlled, patient-maintained propofol sedation in this group of patients, further work is required to confirm its safety.
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Affiliation(s)
- R M Chapman
- Department of Anaesthesia, Glasgow Royal Infirmary, 10 Alexandra Parade, Glasgow G31 2ER, UK.
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Abstract
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.
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Affiliation(s)
- K J Anderson
- University of Glasgow, Department of Anaesthesia, Glasgow Royal Infirmary, 10 Alexandra Parade, Glasgow, UK.
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Leitch JA, Anderson K, Gambhir S, Millar K, Robb ND, McHugh S, Kenny GNC. A partially blinded randomised controlled trial of patient-maintained propofol sedation and operator controlled midazolam sedation in third molar extractions. Anaesthesia 2004; 59:853-60. [PMID: 15310346 DOI: 10.1111/j.1365-2044.2004.03761.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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, anxiety and psychomotor skills were also compared. State anxiety was reduced to a greater extent in the propofol group (mean difference 10 (SD 4) mm; p = 0.010. Propofol patients recovered quicker (mean difference 7 (SD 1.4) min; p = 0.001). Propofol patients had a smaller reduction in arterial oxygen saturation (mean difference 0.8 (SD 0.3)%; p = 0.030), and a reduced increase in heart rate (mean difference 9 (SD 2) beats.min(-1); p < 0.001). Both techniques were well tolerated and safe. Propofol sedation offered superior anxiolysis, quicker recovery, less amnesia and less depression of simple psychomotor function.
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Affiliation(s)
- J A Leitch
- University of Glasgow Dental School, 378 Sauchiehall Street, Glasgow, G2 3JZ, UK.
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Purdie NL, Kenny GNC, McGrady EM. Patient controlled administration of intravenous alfentanil during elective caesarean section under subarachnoid anaesthesia. Int J Obstet Anesth 2004; 12:169-72. [PMID: 15321479 DOI: 10.1016/s0959-289x(02)00186-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/01/2002] [Indexed: 10/27/2022]
Abstract
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 appreciation to the fourth thoracic dermatome was demonstrated. The patient controlled analgesia device was configured to deliver 3 microg.kg(-1) of alfentanil when first actuated. Each subsequent demand delivered 1.5 microg.kg(-1) with a 2-min lock-out interval. Sixty-five percent of women used alfentanil during surgery. The median (IQR) consumption of alfentanil was 360 (278-720) microg. Patient controlled analgesia is a useful method of supplementing subarachnoid anaesthesia for caesarean section. The technique is simple to use and in this group there were no troublesome side effects.
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Affiliation(s)
- N L Purdie
- University Department of Anaesthesia, Glasgow Royal Infirmary, UK.
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Campbell L, Imrie G, Doherty P, Porteous C, Millar K, Kenny GNC, Fletcher G. Patient maintained sedation for colonoscopy using a target controlled infusion of propofol. Anaesthesia 2004; 59:127-32. [PMID: 14725514 DOI: 10.1111/j.1365-2044.2004.03580.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
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 micro g.ml(-1). Four patients became oversedated but required no airway or circulatory interventions. Subjects had a significant reduction in mean (SD) heart rate: 78.7 (15) vs. 69.8 (13.5) (p < 0.001) and in systolic blood pressure 121.1 (13.2) mmHg vs. 96.5 (8.6) mmHg (p < 0.001). Choice reaction time testing 15 min after colonoscopy showed a significant median (IQR [range]) rise of 162 (- 16, 383.3 [-199-859]) ms (p < 0.05). Six patients had faster reaction times postcolonoscopy. All patients denied unpleasant recall and were satisfied with the system. Although oversedation was a problem in this model, we conclude that patient maintained propofol sedation could be possible for colonoscopy.
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Affiliation(s)
- L Campbell
- Department of Anaesthetics, The Royal Sussex County Hospital, Eastern Road, Brighton, BN2 5BE, UK.
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Abstract
BACKGROUND 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 underwent either cardiac surgery or cardiac catheterization procedures. METHODS Twenty-nine children aged 1-15 yr were investigated. General anaesthesia was provided using propofol administered by the Paedfusor system. Accuracy of the system was evaluated by obtaining up to 9 arterial samples for measurement of propofol concentration both during anaesthesia and in the recovery period. Measured arterial propofol concentrations were then compared with values calculated by the Paedfusor. RESULTS The predictive indices of median performance error (MDPE), and median absolute performance error (MDAPE) of the Paedfusor system were found to be 4.1% and 9.7%, respectively and the median value for wobble was 8.3%. These values are much better than those found with the adult 'Diprifusor' system. CONCLUSION The Paedfusor performance was found to be within the accepted limits for use as a TCI system.
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Affiliation(s)
- A Absalom
- University Department of Anaesthesia, Glasgow Royal Infirmary, Queen Elizabeth Building, Alexandra Parade, Glasgow G31 2ER, UK.
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Absalom AR, Kenny GNC. Closed-loop control of propofol anaesthesia using bispectral index: performance assessment in patients receiving computer-controlled propofol and manually controlled remifentanil infusions for minor surgery. Br J Anaesth 2003; 90:737-41. [PMID: 12765888 DOI: 10.1093/bja/aeg137] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND 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 patients undergoing minor surgery under propofol and remifentanil anaesthesia. METHODS Twenty adult patients scheduled for body surface surgery were enrolled. Anaesthesia was manually induced with target-controlled infusions (TCI) of propofol and remifentanil. After the start of surgery, when anaesthesia was clinically adequate, automatic control of the propofol TCI was commenced using the revised closed-loop system. For patients 11-20, effect-site steering was also incorporated into the closed-loop control algorithm. Adequacy of anaesthesia during closed-loop control was assessed clinically, and by calculating the median performance error (MDPE), the median absolute performance error (MDAPE) and the mean offset of the control variable. RESULTS The system provided adequate operating conditions and stable cardiovascular values in all patients during closed-loop control. The mean MDPE and MDAPE were -0.42% and 5.63%, respectively. Mean offset of the BIS from setpoint was -0.2. No patients reported awareness or recall of intraoperative events. CONCLUSIONS The system was able to provide clinically adequate anaesthesia in all patients, with better accuracy of control than in the previous study. There was a tendency for more accurate control in those patients in whom the control algorithm incorporated effect-site steering.
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Affiliation(s)
- A R Absalom
- University Department of Anaesthesia, Glasgow Royal Infirmary, Glasgow, UK.
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Abstract
BACKGROUND 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. METHODS Patients were allocated randomly to receive remifentanil to a target blood concentration of 2 ng ml(-1) (low), 4 ng ml(-1) (medium), or 8 ng ml(-1) (high), administered by target-controlled infusion (TCI). After equilibration, propofol TCI was commenced in closed-loop control, with auditory evoked potentials (AEPex) as the input signal, aiming for an AEPex of 35. This was to ensure a comparable and unbiased level of anaesthesia in all patients. RESULTS We found a dose-dependent decrease in propofol requirements with increasing remifentanil concentrations. The mean (95% CI) propofol target blood concentration during adequate anaesthesia was 4.96 (3.85-6.01) micro g ml(-1) in the low, 3.46 (2.96-3.96) micro g ml(-1) in the medium, and 3.01 (2.20-3.38) micro g ml(-1) in the high group. There was no significant difference when recovery end points were achieved between the groups. Cardiovascular changes were moderate, but most pronounced in the high concentration group, with a decrease in heart rate of 21% compared with baseline. The mean calculated effect site propofol concentration at loss of consciousness was 2.08 (1.85-2.32) micro g ml(-1), and at recovery of consciousness was 1.85 (1.68-2.00) micro g ml(-1). CONCLUSIONS This study confirms a synergistic interaction between remifentanil and propofol during surgery, whereas the contribution of remifentanil in the absence of stimulation seems limited. In addition, our results suggest that the propofol effect site concentration provides a guide to the value at which the patient recovers consciousness.
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Affiliation(s)
- S E Milne
- University of Glasgow, Department of Anaesthesia, Glasgow Royal Infirmary, UK
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Milne SE, Troy A, Irwin MG, Kenny GNC. Relationship between bispectral index, auditory evoked potential index and effect-site EC50 for propofol at two clinical end-points. Br J Anaesth 2003; 90:127-31. [PMID: 12538366 DOI: 10.1093/bja/aeg035] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND 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. METHODS Forty unpremedicated Caucasian patients were anaesthetized with i.v. propofol delivered by a Diprifusor target-controlled infusion (TCI). Bispectral index (BIS) and auditory evoked potential index (AEPex) were measured and blood and effect-site propofol concentrations were predicted. Logistic regression was used to estimate population values for predicted blood and effect-site propofol concentrations at the clinical end-points and to correlate these with BIS and AEPex. RESULTS The effect-site EC(50) at loss of consciousness was 2.8 micro m ml(-1) with an EC(05) and an EC(95) of 1.5 and 4.1 micro m ml(-1), respectively. The predicted EC(50) when there was no response to a tetanic stimulus was 5.2 micro m ml(-1) with an EC(05) and an EC(95) of 3.1 and 7.2 micro m ml(-1), respectively. CONCLUSIONS Unconsciousness and lack of response to a painful stimulus occur within a defined range of effect-site concentrations, predicted by Diprifusor TCI software.
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Affiliation(s)
- S E Milne
- University of Glasgow, Department of Anaesthesia, Glasgow Royal Infirmary, 10 Alexandra Parade, Glasgow G31 2ER, UK
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Leitch JA, Sutcliffe N, Kenny GNC. Patient-maintained sedation for oral surgery using a target-controlled infusion of propofol - a pilot study. Br Dent J 2003; 194:43-5. [PMID: 12540939 DOI: 10.1038/sj.bdj.4802412] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2002] [Accepted: 09/23/2002] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To assess the safety and efficacy of a new patient-maintained propofol system for conscious sedation in dentistry. DESIGN Prospective clinical trial SETTING Department of Sedation, Glasgow Dental Hospital and School, 2001 SUBJECTS AND METHODS Patients scheduled for oral surgery with conscious sedation. Exclusions included ASA IV -V, inability to use the handset, opioid use and severe respiratory disease. INTERVENTIONS Patients were given intravenous propofol to a level of 1.0 microg/ml (reducing from 1.5 microg/ml) using a target controlled infusion system, they then controlled their sedation level by double-clicking a handset which on each activation increased the propofol concentration by 0.2 microg/ml. MAIN OUTCOME MEASURES Oxygen saturation, patient satisfaction, and surgeon satisfaction. RESULTS Twenty patients were recruited, 16 female and four male. Nineteen patients completed sedation and treatment successfully. Mean lowest oxygen saturation was 94%. No patients were over-sedated. All patients successfully used the system to maintain a level of sedation adequate for their comfort. Patient and surgeon satisfaction were consistently high. CONCLUSIONS Initial experience with this novel system has confirmed safety, patient satisfaction and surgeon satisfaction.
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Affiliation(s)
- J A Leitch
- Glasgow Dental Hospital and School, Glasgow.
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Abstract
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 was 2.3 (1.7-3.6) microg.ml(-1). The performance characteristics of the system were excellent, with a median absolute performance error of 7 (1-15). Patients were drowsy yet rousable, with a median (range) BIS set-point of 80 (75-85). No patient became apnoeic, required airway support or became haemodynamically unstable whilst sedated. Eight patients moaned or moved during colonoscopy and four had recall. Median (range) time to full consciousness was 4 (2-20) min after the end of closed-loop control. Patient and surgeon satisfaction were high. We conclude that BIS may be a suitable control variable for closed-loop control of sedation with propofol.
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Affiliation(s)
- K Leslie
- University Department of Anaesthesia, Southern General Hospital, Glasgow, Scotland, UK.
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Abstract
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 lockout period to 4 min,reducing the starting concentration to 0.5 microg x ml(-1) and the increments on demand to 0.1 microg x ml(-1). As in the previous study, healthy volunteers attempted to render themselves unconscious by frequently pressing the demand button. To assess effects on memory, volunteers were given keywords to remember every 15 min. The maximum target concentration reached varied between 1.0 and 2.5 microg x ml(-1). No volunteers lost consciousness, however, one volunteer had a brief period of apnoea and oxygen desaturation. The Cp50 for loss of memory for words was 1.26 microg x ml(-1). Although this version represents an improvement, we conclude that the system is not yet completely suitable for use without anaesthetic supervision.
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Affiliation(s)
- F Henderson
- Department of Anaesthesia, Western Infirmary, Glasgow, UK
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Abstract
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 used to calculate the predicted propofol blood and effect site concentrations required to produce unconsciousness and no response to a noxious stimulus in 50% and 95% of patients and to correlate BIS with these end-points. The Diprifusor TCI software produces anaesthesia at consistent target concentrations. Bispectral index correlates well with clinical end-points and may be useful during propofol anaesthesia.
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Affiliation(s)
- M G Irwin
- Department of Anaesthesiology, University of Hong Kong, Room 424, K Block, Queen Mary Hospital, Pokfulam Road, Hong Kong.
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Milne SE, Horgan PG, Kenny GNC. Target-controlled infusions of propofol and remifentanil with closed-loop anaesthesia for hepatic resection. Anaesthesia 2002; 57:93. [PMID: 11843757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
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Kenny GNC. News, Trends & Techniques. J Med Eng Technol 1980. [DOI: 10.3109/03091908009161135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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