On-line Monitoring of End-tidal Propofol Concentration in Anesthetized Patients.
Takita, Akira M.D. ; Masui, Kenichi M.D., Ph.D. ; Kazama, Tomiei M.D., Ph.D.  
Anesthesiology. 106(4):659-664, April 2007.

Clinical Investigations

Abstract:
Background: Propofol (2,6-diisopropylphenol) has some volatility, so it can be detected in expired breath of individuals receiving intravenous propofol. This study measured volatile propofol exhaled by patients and investigated the relation between exhaled and plasma propofol concentrations.
Methods: Nineteen patients with American Society of Anesthesiologists physical status I or II who were undergoing elective surgery participated in this two-part study. In study 1 (n = 11), anesthesia was induced with 2 mg/kg propofol, 0.1 mg/kg vecuronium, and 2 [mu]g/kg fentanyl. After intubation, propofol was administered continuously for 60 min at each of three rates: 3, 6, and 9 mg [middle dot] kg-1 [middle dot] h-1. Blood samples were obtained just before each change in the infusion rate, and the plasma concentrations of propofol were measured. The exhaled propofol concentration was measured continuously by means of proton transfer mass spectrometry. End-tidal propofol concentrations during blood sampling were averaged and compared with plasma propofol concentrations. In study 2 (n = 8), after induction of anesthesia, patients received a bolus injection of 2 mg/kg propofol, and the exhaled propofol concentration was measured.
Results: Volatile propofol was detected in expired gas from all study patients. From study 1, the authors obtained 24 paired data points, i.e., concentrations of end-tidal and plasma propofol. With Bland-Altman analysis, bias +/- precision was 5.2 +/- 10.4 with 95% limits of agreement of -15.1 and 25.6. In study 2, the exhaled propofol concentration curve showed an obvious peak in all patients.
Conclusions: Agreement between plasma and exhaled propofol concentrations suggests that proton transfer mass spectrometry can be used for real-time propofol monitoring.

Real-time Monitoring of Propofol in Expired Air in Humans Undergoing Total Intravenous Anesthesia.
Hornuss, Cyrill M.D. ; Praun, Siegfried M.Sc., Ph.D. ; Villinger, Johannes Ph.D. ; Dornauer, Albert ; Moehnle, Patrick M.D. ; Dolch, Michael M.D. ; Weninger, Ernst M.D. ; Chouker, Alexander M.D. ; Feil, Christian M.S. ; Briegel, Josef M.D., Ph.D. ; Thiel, Manfred M.D., Ph.D.; Schelling, Gustav M.D., Ph.D. 
Anesthesiology. 106(4):665-674, April 2007.

Clinical Investigations

Abstract:
Background: The physicochemical properties of propofol could allow diffusion across the alveolocapillary membrane and a measurable degree of pulmonary propofol elimination. The authors tested this hypothesis and showed that propofol can be quantified in expiratory air and that propofol breath concentrations reflect blood concentrations. This could allow real-time monitoring of relative changes in the propofol concentration in arterial blood during total intravenous anesthesia.
Methods: The authors measured gas-phase propofol using a mass spectrometry system based on ion-molecule reactions coupled with quadrupole mass spectrometry which provides a highly sensitive method for on-line and off-line measurements of organic and inorganic compounds in gases. In a first sequence of experiments, the authors sampled blood from neurosurgery patients undergoing total intravenous anesthesia and performed propofol headspace determination above the blood sample using an auto-sampler connected to the mass spectrometry system. In a second set of experiments, the mass spectrometry system was connected directly to neurosurgery patients undergoing target-controlled infusion via a T piece inserted between the endotracheal tube and the Y connector of the anesthesia machine, and end-expiratory propofol concentrations were measured on-line.
Results: A close correlation between propofol whole blood concentration and propofol headspace was found (range of Pearson r, 0.846-0.957; P < 0.01; n = 6). End-expiratory propofol signals mirrored whole blood values with close intraindividual correlations between both parameters (range of Pearson r, 0.784-0.985; n = 11).
Conclusion: Ion-molecule reaction mass spectrometry may allow the continuous and noninvasive monitoring of expiratory propofol levels in patients undergoing general anesthesia.

Analysis of Deaths Related to Anesthesia in the Period 1996-2004 from Closed Claims Registered by the Danish Patient Insurance Association.
Hove, Lars Dahlgaard M.D. ; Steinmetz, Jacob M.D. ; Christoffersen, Jens Krogh M.D. ; Moller, Ann M.D. ; Nielsen, Jacob M.D. ; Schmidt, Henrik M.D. 
Anesthesiology. 106(4):675-680, April 2007.

Clinical Investigations

Abstract:
Background: Anesthesia is associated with complications, and some of them may be fatal. The authors investigated the circumstances under which deaths were associated with anesthesia. In Denmark, the specialty anesthesiology encompasses emergency medicine, chronic and acute pain medicine, anesthetic procedures, perioperative care medicine, and intensive care medicine.
Methods: The authors retrospectively investigated anesthesia related deaths registered by the Danish Patient Insurance Association.
Results: From 1996 to 2004, 27,971 claims were made by the Danish Patient Insurance Association covering all medical specialties, of which 1,256 files (4.5%) were related to anesthesia. In 24 cases, the patient's death was considered to result from the anesthetic procedure: 4 deaths were related to airway management, 2 to ventilation management, 4 to central venous catheter placement, 4 as a result of medication errors, 4 from infusion pump problems, and 4 after complications from regional blockades. Severe hemorrhage caused 1 death, and in 1 case the cause was uncertain.
Conclusions: Several of the 24 deaths could potentially have been avoided by more extended use of airway algorithm, thorough preoperative evaluation, training, education, and use of protocols for diagnosis and treatment.

ACTA ANAESTHESIOLOGICA SCANDINAVICA - TOP

Sustained intravascular exposure to propofol does not prolong pain at the site of injection
E. Liljeroth, A. Karlsson, M. Lagerkranser, J. Åkeson
Acta Anaesthesiologica Scandinavica 2007;51 (4), 456–459.

Background: Pain at the site of intravenous injection of propofol is a common clinical finding. This double-blind, randomized cross-over study was designed to evaluate whether venous occlusion applied during injection of a low dose of propofol reduces the intensity of pain at the site of injection compared with no occlusion.
Methods: Bilateral 0.5-ml injections of an emulsion containing 10 mg/ml of propofol were given over 30 s in 75 adult surgical patients. Each patient was given one injection with and one without 60-s occlusion of the cannulated vein with a 10-min interval, and asked to score the maximal pain intensity on a visual analogue scale (VAS).
Results: The maximal pain intensity [median (25th percentile; 75th percentile), range] at the site of injection was 0.5 (0; 3.5), 0–8.0 VAS units with venous occlusion and 0.5 (0; 1.4), 0–6.0 VAS units without occlusion (P = 0.042). Pain was first reported within 20 s regardless of the study regimen and was not prolonged by local venous occlusion.
Conclusion: Venous occlusion augments pain intensity at the site of propofol injection without prolonging pain, implying that propofol-induced pain is determined more by the blood concentration than by the duration of intravascular exposure. The low intensity of pain induced by low-dose propofol and the fading of pain despite sustained exposure suggest that initial low-dose administration of propofol should be evaluated for the attenuation of local pain induced by higher intravenous doses of propofol.

Low-dose propofol reduces the incidence of moderate to severe local pain induced by the main dose
E. Liljeroth, A. Karlsson, M. Lagerkranser, J. Åkeson
Acta Anaesthesiologica Scandinavica 2007; 51 (4), 460–463.

Background: Local pain on injection of propofol remains a considerable problem in clinical anaesthesiology. As slow infusion of a low dose of propofol induces little or no pain at the site of injection, and as propofol-induced pain fades during prolonged exposure, this randomized, double-blind, clinical cross-over study was designed to test whether pain on injection of propofol is attenuated by initial slow injection of a low dose of propofol by the same intravenous line.
Methods: Seventy-seven adult surgical patients were cannulated in a dorsal vein on each hand. In each cannula, a 0.5-ml priming dose of either propofol 10 mg/ml dissolved in an emulsion of medium- and long-chain triglycerides or aqueous sodium chloride 9.0 mg/ml was injected over 30 s, and followed 120 s later by a main dose of 2.0 ml of the same propofol formula over 6 s. After each injection, the patients were asked by a blind investigator to score the maximal pain intensity on a visual analogue scale (VAS).
Results: Although the decrease in maximal pain intensity did not reach statistical significance (P = 0.070), significantly fewer patients reported moderate or severe pain intensity (corresponding to 3.0 VAS units or more) after the main dose of propofol was preceded by a priming dose of propofol than by sodium chloride (P = 0.041).
Conclusions: The incidence of moderate to severe local pain induced by intravenous propofol can be decreased by a readily applicable technique in which a low dose of propofol emulsion is slowly administered by the same intravenous route 2 min in advance.

Post-operative recovery profile after laparoscopic cholecystectomy: a prospective, observational study of a multimodal anaesthetic regime
K. Jensen, H. Kehlet, C. M. Lund
Acta Anaesthesiologica Scandinavica 2007; 51 (4), 464–471.

Background: Laparoscopic cholecystectomy is now often an ambulatory procedure, but dependent on short-term post-operative complaints of pain and post-operative nausea and vomiting (PONV). The efficacy of post-anaesthesia care units (PACUs) is therefore important to facilitate return to normal functions. We investigated the feasibility and efficacy of a standardized, evidence-based anaesthesia/analgesic regime to identify residual problems in the early post-operative phase.
Methods: One hundred and thirty-four consecutive patients admitted for elective laparoscopic cholecystectomy at Hvidovre University Hospital between 15 March and 30 September 2005 were included in the study. The standardized, evidence-based regime consisted of total intravenous (i.v.) anaesthesia (propofol-remifentanil), well-defined fluid therapy, dexamethasone, ketorolac, ondansetron, sufentanil and incisional bupivacaine intra-operatively, and in the PACU on demand (prn) administration of sufentanil, morphine, paracetamol, ondansetron, droperidol, oral fluids and oxygen (if SpO2 < 93%) with PACU discharge using a modified Aldrete score.
Results: Protocol violations were moderate and occurred unsystematically, 8% had medical violations and 10% did not receive the pre-planned fluid amount. Severe PONV was seen in 2%. Thirteen per cent experienced severe pain, and the presence of any pain and/or PONV were predictors of an extended PACU stay. Mean oxygen demand was 46 min (range, 0–300 min), which influenced time to discharge (mean, 88 min). There were on average 2.7 treatment interventions (range, 0–11) before discharge.
Conclusion: An evidence-based, multimodal approach to the anaesthetic/analgesic management in laparoscopic cholecystectomy is feasible and advantageous in the early post-operative phase. Pain and PONV are predictors of a complicated recovery profile and deserve further attention. Transient oxygen desaturations postpone discharge from the PACU, but the clinical significance of this fact is questionable.

BRITISH JOURNAL OF ANAESTHESIA - TOP

Dexmedetomidine infusion as a supplement to isoflurane anaesthesia for vitreoretinal surgery
Y. Y. S. Lee, S. M. Wong and C. T. Hung
British Journal of Anaesthesia 2007 98(4):477-483

Background: We explored the sympatholytic property of dexmedetomidine, especially its role in intraocular pressure (IOP) reduction, haemodynamic stability, and attenuation of extubation response.
Method: In this double-blind, randomized, controlled trial approved by the Hospital Ethics Committee, 60 patients undergoing elective vitreoretinal surgery were allocated to two groups, receiving either placebo or dexmedetomidine. A loading dose of dexmedetomidine 2.5 µg kg–1 h–1 (or placebo in same volume) was infused for 10 min immediately before induction of anaesthesia with propofol, followed by a maintenance dexmedetomidine or placebo infusion at 0.4 µg kg–1 h–1 till 30 min before the end of the operation. Anaesthesia was maintained with isoflurane, oxygen, and air mixture. IOP was measured before the loading dose and 1 min after tracheal intubation. The mean arterial pressure (MAP) and heart rate (HR) during loading, induction, maintenance, extubation, and recovery period were measured. The degree of strain on extubation was graded from 0 to 5.
Results: The use of vasopressor/labetalol/atropine and the reduction in IOP were comparable between the two groups. There was a significant variation in MAP and HR over time within group, but not between groups. The median degree of strain was significantly lower (P = 0.049), and the time to reach Aldrete score of 10 shorter (P = 0.031) in the dexmedetomidine group.
Conclusion: Dexmedetomidine can be used without undue haemodynamic fluctuation and can decrease the excitatory response during extubation. The reduction in IOP with dexmedetomidine was comparable with placebo.

Randomized comparison of two anti-emetic strategies in high-risk patients undergoing day-case gynaecological surgery
H. White, R. J. Black, M. Jones and G. C. Mar Fan
British Journal of Anaesthesia 2007 98(4):470-476

Background: Postoperative nausea and vomiting (PONV) is a significant cause of morbidity among patients undergoing general anaesthesia. The optimal strategy for prevention of PONV, however, remains unclear. This study compared two commonly used prophylactic strategies in high-risk, day-case, gynaecological surgery patients.
Methods: We conducted a randomized trial comparing sevoflurane combined with dolasetron (SD), with propofol-based total intravenous anaesthesia (TIVA) in 126 high-risk patients undergoing day-case gynaecological surgery. The primary endpoints included the incidence and severity of nausea or vomiting before discharge and the incidence of nausea or vomiting between discharge and 24 h. To identify the factors most predictive of a complete response (no PONV at any time within the 24 h period), multiple logistic regression models were fitted.
Results: Before discharge, there was no significant difference between the two treatment groups with respect to nausea and vomiting outcomes (P = 0.3). Post-discharge nausea and vomiting (PDNV), however, were significantly more common for patients in the TIVA group (nausea, P = 0.004 and vomiting, P = 0.03). Type of anaesthetic, adjusted for weight and anaesthesia duration was significantly associated with complete response (odds ratio = 2.7, 95% confidence interval = 1.15 to 6.4).
Conclusions: Although both TIVA and dolasetron prophylaxis reduce the predicted rate of PONV in the early postoperative period, the anti-emetic effects of propofol are short-lived. A longer-acting drug such as dolasetron may therefore be necessary to prevent PDNV.

CANADIAN JOURNAL OF ANESTHESIA - TOP

Transdermal diclofenac patch vs eutectic mixture of local anesthetics for venous cannulation pain
Anil Agarwal, MD, Sujeet Gautam, MBBS, Devendra Gupta, MD and Uttam Singh, PhD
Canadian Journal of Anesthesia 54:196-200 (2007)

Purpose: To compare the efficacy and side effects of transdermal diclofenac patch with eutectic mixture of local anesthetic (EMLA) cream in attenuating venous cannulation pain.
Methods: Adult ASA I or II patients undergoing elective surgery were randomly divided into three groups of 150 each. Group 1 (Control) patients received a placebo patch; Group 2 (EMLA) patients received EMLA cream; Group 3 (Diclofenac) patients received a transdermal diclofenac patch. The patches were applied at the proposed venous cannulation site 60 min prior to cannulation and pain resulting from an 18G cannula was assessed on an ten-point visual analogue scale (VAS). The cannulation site was observed for blanching, erythema, induration and edema for up to 24 hr.
Results: The incidence of venous cannulation pain was 100% in the control group, as compared to 37% and 48% of patients who experienced pain in the EMLA (P = 0.001) and diclofenac (P = 0.001) groups, respectively. The severity of venous cannulation pain [median (VAS) with interquartile ranges] was also higher in the control group: 6 (3) as compared to VAS sores of 0 (1) and 0 (2) in the EMLA (P = 0.001) and diclofenac (P = 0.001) groups. Blanching occurred with greater frequency in the EMLA group compared with the diclofenac (P = 0.001 at six hours) and placebo groups (P = 0.001 at six hours). Erythema, induration and edema were reduced in the diclofenac group compared with the EMLA (P = 0.001 for all comparisons) and placebo groups (P = 0.04 for edema at six hours and P = 0.001 for other comparisons).
Conclusion: Transdermal diclofenac patch and EMLA are equally effective in reducing venous cannulation pain, but signs of erythema, induration and edema are less frequently observed with the transdermal diclofenac patch.

Medical malpractice and anesthesiology: literature review and role of the expert witness
Edward Crosby, MD FRCPC
Canadian Journal of Anesthesia 54:227-241 (2007)
 
Purpose: To provide a narrative review of the physician experience of medical malpractice litigation applied to an anesthesiology case with particular emphasis on the role played by medical expert witnesses.
Sources: Literature searches were conducted of English-language medical publications published between 1996 – 2006 using both Medline and Pubmed databases. Key words included: "medical malpractice"; "medical malpractice litigation"; "medical expert witness"; "expert witness liability", "expert witness bias"; "hindsight bias"; and "outcome bias".
Principal findings: Patient injury resulting from medical care is common but most injured patients do not sue. Implicit review of medical files is biased to an important degree by the occurrence of severe injury; care is more often deemed substandard when the resulting injury is severe. Expert analysis of medical mal-occurrences is influenced by both hindsight and outcome bias. Compensation for those who do sue is influenced by the severity of injury and the degree of disability. The activity of experts is not commonly subject to review by peers, professional groups or licensing authorities.
Conclusions: The legal process for resolving patient claims against physicians is well delineated and transparent; its operational features are complex and prejudiced by severe outcomes. Bias is pervasive in the analysis of medical occurrences and may result in findings against caregivers which are unfair.

PUB MED - TOP

Just ASC: how to formulate the question.
Coben CE, Koonsman GS.
Informed Healthcare Media, Dallas, USA. chad@informedllc.com
Healthc Financ Manage. 2007 Apr;61(4):88-92.

When a hospital is considering whether to expand or transform its approach to outpatient surgery business, its internal financial and operating reports can help clarify trends and provide insight into the performance of the existing business over time. Benchmarking data can allow a hospital to compare its estimated performance for a proposed ambulatory surgery center with the actual performance of comparable existing facilities. Financial leaders need to be able to combine internal and external data into a pro forma to help determine whether to move ahead with plans to develop the ASC.

Improving efficiencies in the GI practice of endoscopic ambulatory surgery center.
Overholt BF. Gastrointestinal Associates, PC, Knoxville, TN 37950-9002, USA. bfoverholt@gihealthcare.com
J Clin Gastroenterol. 2007 Apr;41(4):352-5.

The practice of gastroenterology is undergoing sweeping changes that demand improvements in efficiency and effectiveness within the practice and ambulatory endoscopy centers. This article discusses core principles of practice and endoscopic ambulatory surgery center function and management that lead to the improvements in the delivery of efficient, quality care.

Perioperative management of the diabetic patient.
Bergman SA., Professor, Department of Oral Maxillofacial Surgery, Baltimore College of Dental Surgery, University of Maryland, Baltimore, MD.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007 Mar 20;

Diabetes mellitus is a significant global public health problem and is a major source of morbidity and mortality in the world today. Type 2 diabetes mellitus is the predominant form of diabetes worldwide and represents approximately 90% of all cases. There is an epidemic of type 2 diabetes mellitus in the world today in both developed and developing countries. Globally, it is expected that the number of people with diabetes will increase from the current 150 million to 220 million by the year 2010 and to 300 million by the year 2025. In addition, there has been an alarming increase in the incidence of type 2 diabetes in children and adolescents. It is therefore increasingly likely that diabetic patients will appear for dental and oral maxillofacial surgical treatment in both the office and ambulatory surgery clinic setting. Surgical stress often produces hyperglycemia in the perioperative period. Hyperglycemia has been shown to cause a significant increase in perioperative morbidity and mortality. It is the general consensus that strict glycemic control is beneficial and should be achieved for diabetic patients in the perioperative period. Preoperative, intraoperative, and postoperative management protocols for improved perioperative glycemic control of both type 1 and type 2 diabetics are presented.

Patient safety in the office-based setting.
Horton JB, Reece EM, Broughton G 2nd, Janis JE, Thornton JF, Rohrich RJ.
Department of Plastic Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Plast Reconstr Surg. 2006 Apr;117(4):61e-80e.
Comment in:
Plast Reconstr Surg. 2007 Mar;119(3):1128-9; author reply 1129.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Discern the importance of the physician's office administrative capacity. 2. Recognize the necessity of a system for quality assessment. 3. Assess which procedures are safe in the office-based setting. 4. Know the basic steps to properly evaluate patients for office-based plastic surgery.
BACKGROUND: At least 44,000 Americans die annually as a result of preventable medical errors. Medical mistakes are the eighth leading cause of death in the United States, costing between $54.6 billion and $79 billion, or 6 percent of total annual national health care expenditures. Office-based procedures comprise a 10-fold increase in risk for serious injury or death as compared with an ambulatory surgical facility.
METHODS: This article reviews the literature on office-based patient safety issues. It places special emphasis on the statements and advisories published by the American Society of Plastic Surgeons' convened Task Force on Patient Safety in Office-Based Settings. This article stresses areas of increased patient safety concern, such as deep vein thrombosis prophylaxis and liposuction surgery. RESULTS: The article divides patient safety in health care delivery into three broad categories. First, patient safety starts with emphasis at the administrative level. The physician or independent governing body must develop a system of quality assessment that functions to minimize preventable errors and report outcomes and errors. Second, the clinical aspects of patient safety require that the physician evaluate whether the procedure(s) and the patient are proper for the office setting. Finally, this article gives special attention to liposuction, the most frequently performed office-based plastic surgery procedure.
CONCLUSIONS: Patient safety must be every physician's highest priority, as reflected in the Hippocratic Oath: primum non nocere ("first, do no harm"). In the office setting, this priority requires both administrative and clinical emphasis. The physician who gives the healing touch of quality care must always have patient safety as the foremost priority.

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