Zeev Friedman

Stroke volume variation as a predictor of fluid responsiveness in patients undergoing brain surgery.

Changes in arterial blood pressure induced by mechanical ventilation allow assessment of cardiac preload. In this study, stroke volume variation (SVV), which is the percentage change between the maximal and minimal stroke volumes (SV) divided by the average of the minimum and maximum over a floating period of 30 s, continuously displayed by the PiCCO continuous cardiac output monitor, was evaluated as a predictor of fluid responsiveness. Fifteen patients undergoing brain surgery were included. During surgery, graded volume loading was performed with each volume loading step (VLS) consisting of 100 mL of 6% hydroxyethylstarch given for 2 min. Successive responsive VLSs were performed (increase in SV > 5% after a VLS) until a change in SV of <5% was reached (nonresponsive). A total of 140 VLSs were performed. Responsive and nonresponsive VLSs differed in their pre-VLS values of systolic blood pressure, SV, and SVV, but not in the values of heart rate and central venous pressure. By using receiver operating characteristic analysis, the area under the curve for SVV (0.870, 95% confidence interval [CI]: 0.809 to 0.903) was statistically more than those for central venous pressure (0.493, 95% CI: 0.397 to 0.590, P = 7 × 10−10), heart rate (0.593, 95% CI: 0.443 to 0.635, P = 5.7 × 10−10), and systolic blood pressure (0.729, 95% CI: 0.645 to 0.813, P = 4.3 × 10-3). An SVV value of 9.5% or more, will predict an increase in the SV of at least 5% in response to a 100-mL volume load, with a sensitivity of 79% and a specificity of 93%.

Preoperative use of statins is associated with reduced early delirium rates after cardiac surgery.

Background:Delirium is an acute deterioration of brain function characterized by fluctuating consciousness and an inability to maintain attention. Use of statins has been shown to decrease morbidity and mortality after major surgical procedures. The objective of this study was to determine an association between preoperative administration of statins and postoperative delirium in a large prospective cohort of patients undergoing cardiac surgery with cardiopulmonary bypass. Methods:After Institutional Review Board approval, data were prospectively collected on consecutive patients undergoing cardiac surgery with cardiopulmonary bypass from April 2005 to June 2006 in an academic hospital. All patients were screened for delirium during their hospitalization using the Confusion Assessment Method in the intensive care unit. Multivariable logistic regression analysis was used to identify independent perioperative predictors of delirium after cardiac surgery. Statins were tested for a potential protective effect. Results:Of the 1,059 patients analyzed, 122 patients (11.5%) had delirium at any time during their cardiovascular intensive care unit stay. Administration of statins had a protective effect, reducing the odds of delirium by 46%. Independent predictors of postoperative delirium included older age, preoperative depression, preoperative renal dysfunction, complex cardiac surgery, perioperative intraaortic balloon pump support, and massive blood transfusion. The model was reliable (Hosmer-Lemeshow test, P = 0.3) and discriminative (area under receiver operating characteristic curve = 0.77). Conclusions:Preoperative administration of statins is associated with the reduced risk of postoperative delirium after cardiac surgery with cardiopulmonary bypass.

Patient selection in ambulatory anesthesia — An evidence-based review: part II

PurposeTo identify and characterize the evidence supporting decisions made in the care of patients with selected medical conditions undergoing ambulatory anesthesia and surgery. Conditions highlighted in this review include: the elderly heart transplantation, hyper-reactive airway disease, coronary artery disease, and obstructive sleep apnea.SourceA structured search of MEDLINE ( 1966–2003) was performed using keywords for ambulatory surgery and patient condition. Selected articles were assigned a level of evidence using Centre for Evidence Based Medicine (CEBM) criteria. Recommendations were also graded using CEBM criteria.Principal findingsThe elderly may safely undergo ambulatory surgery but are at increased risk for hemodynamic variation in the operating room. The heart transplant recipient is at increased risk of coronary artery disease and renal insufficiency and should undergo careful preoperative evaluation. The patient with reactive airway disease is at increased risk of minor respiratory complications and should be encouraged to quit smoking. The patient with coronary artery disease and recent myocardial infarction may undergo ambulatory surgery without stress testing if functional capacity is adequate. The patient with obstructive sleep apnea is at increased risk of difficult tracheal intubation but the likelihood of airway obstruction and apnea following ambulatory surgery is unknown.ConclusionAmbulatory anesthesia is infrequently associated with adverse outcomes, however, knowledge regarding specific patient conditions is of generally low quality. Few prospective trials are available to guide management decisions.RésuméObjectifIdentifier et caractériser la preuve à l’appui des décisions prises sur les soins à donner aux patients qui présentent des pathologies médicales ciblées et qui subissent une anesthésie en chirurgie ambulatoire. Les situations sélectionnées dans cette revue comprennent : la vieillesse, la transplantation cardiaque, l’affection respiratoire hyper-réactionnelle, la coronaropathie et l’apnée obstructive du sommeil.SourceUne recherche structurée dans MEDLINE (1966–2003) a été réalisée selon les mots dés pour la chirurgie ambulatoire et l’état du patient. Les articles choisis ont été cotés selon le niveau de preuve des critères du Centre for Evidence Based Medicine (CEBM). Les recommandations ont aussi été graduées selon les critères du CEBM.Constatations principalesLes personnes âgées peuvent subir une opération ambulatoire en toute sécurité, mais sont plus à risque de variation hémodynamique en salle d’opération. Les greffés cardiaques sont plus à risque de coronaropathie et d’insuffisance rénale et doivent avoir une évaluation préopératoire minutieuse. Les cas d’affection respiratoire réactionnelle sont plus à risque de complications respiratoires mineures et doivent être encouragés à cesser de fumer. Le patient atteint de coronaropathie, victime récente d’infarctus myocardique, peut être vu en chirurgie ambulatoire sans épreuve d’effort si la capacité fonctionnelle est adéquate. En cas d’apnée obstructive du sommeil, il y a plus de risque de difficulté d’intubation trachéale, mais la possibilité d’obstruction des voies aériennes et d’apnée à la suite d’une opération ambulatoire n’est pas connue.ConclusionLanesthésie ambulatoire n’est pas souvent associée à des complications, même si la connaissance de pathologies spécifiques est peu développée en général. Il existe peu d’études prospectives permettant de guider les décisions thérapeutiques.

A Perioperative Smoking Cessation Intervention with Varenicline A Double-blind, Randomized, Placebo-controlled Trial

Background:The efficacy of perioperative tobacco interventions on long-term abstinence and the safety of smoking cessation less than 4 weeks before surgery is unclear. Our objective was to determine the efficacy and safety of a perioperative smoking cessation intervention with varenicline to reduce smoking in elective surgical patients. Methods:In a prospective, multicenter, double-blind, placebo-controlled trial, 286 patients were randomized to receive varenicline or placebo. Both groups received in-hospital and telephone counseling during 12 months. The primary outcome was the 7-day point prevalence abstinence rate 12 months after surgery. Secondary outcomes included abstinence at 3 and 6 months after surgery. Multivariable logistic regression was used to identify independent variables related to abstinence. Results:The 7-day point prevalence abstinence at 12 months for varenicline versus placebo was 36.4% versus 25.2% (relative risk: 1.45; 95%: CI: 1.01–2.07; P = 0.04). At 3 and 6 months, the 7-day point prevalence abstinence was 43.7% versus 31.9% (relative risk: 1.37; 95% CI: 1.01 to 1.86; P = 0.04), and 35.8% versus 25.9% (relative risk: 1.43; 95%: CI 1.01–2.04; P = 0.04) for varenicline versus placebo, respectively. Treatment with varenicline (odds ratio: 1.76; 95% CI: 1.03–3.01; P = 0.04), and preoperative nicotine dependence (odds ratio: 0.82, 95% CI: 0.68 to 0.98; P = 0.03) predicted abstinence at 12 months. The adverse events profile in both groups was similar except for nausea, which occurred more frequently for varenicline versus placebo (13.3% vs. 3.7%, P = 0.004). Conclusions:A perioperative smoking cessation intervention with varenicline increased abstinence from smoking 3, 6, and 12 months after elective noncardiac surgery with no increase in serious adverse events.

Ultrasound Improves Cricothyrotomy Success in Cadavers with Poorly Defined Neck Anatomy: A Randomized Control Trial.

Background: Misidentification of the cricothyroid membrane in a “cannot intubate-cannot oxygenate” situation can lead to failures and serious complications. The authors hypothesized that preprocedure ultrasound-guided identification of the cricothyroid membrane would reduce complications associated with cricothyrotomy. Methods: A group of 47 trainees were randomized to digital palpation (n = 23) and ultrasound (n = 24) groups. Cricothyrotomy was performed on human cadavers by using the Portex® device (Smiths Medical, USA). Anatomical landmarks of cadavers were graded as follows: grade 1—easy = visual landmarks; 2—moderate = requires light palpation of landmarks; 3—difficult = requires deep palpation of landmarks; and 4—impossible = landmarks not palpable. Primary outcome was the complication rate as measured by the severity of injuries. Secondary outcomes were correct device placement, failure to cannulate, and insertion time. Results: Ultrasound guidance significantly decreased the incidence of injuries to the larynx and trachea (digital palpation: 17 of 23 = 74% vs. ultrasound: 6 of 24 = 25%; relative risk, 2.88; 95% CI, 1.39 to 5.94; P = 0.001) and increased the probability of correct insertion by 5.6 times (P = 0.043) in cadavers with difficult and impossible landmark palpation (digital palpation 8.3% vs. ultrasound 46.7%). Injuries were found in 100% of the grades 3 to 4 (difficult–impossible landmark palpation) cadavers by digital palpation compared with only 33% by ultrasound (P < 0.001). The mean (SD) insertion time was significantly longer with ultrasound than with digital palpation (196.1 s [60.6 s] vs. 110.5 s [46.9 s]; P < 0.001). Conclusion: Preprocedure ultrasound guidance in cadavers with poorly defined neck anatomy significantly reduces complications and improves correct insertion of the airway device in the cricothyroid membrane.

Experience is not enough: repeated breaches in epidural anesthesia aseptic technique by novice operators despite improved skill.

Background:Invasive procedures such as epidural anesthesia carry risks for complications such as erroneous placement arising from inadequate manual skills and infection secondary to breaches in aseptic technique. Although it is assumed that improvement in aseptic technique parallels improved dexterity, this assertion remains unproven. The aim of this study was to determine whether increased proficiency in the manual skills for epidural anesthesia is associated with improved aseptic technique. Methods:Second-year anesthesia residents were repeatedly videotaped performing epidural anesthesia over 6-month periods. Three independent examiners blinded to the level of training of the residents evaluated the procedures for manual skills and aseptic technique. Each procedure was graded using a manual skills checklist, a global rating scale, and an aseptic technique checklist. The main outcome measures were the scores for these three tools. Results:Thirty-five sessions were videotaped over 1 yr. Interrater reliability was nearly perfect. A strong positive association was found between increased experience and manual skills, as reflected by the scores achieved on both the manual skills checklist and the global rating scale. In contrast, a nonsignificant or very weak correlation was found between the aseptic technique checklist total scores and the number of epidurals performed. Conclusion:Manual skills for invasive procedures improved with increasing experience, but aseptic technique did not, despite formal teaching. These findings reflect major gaps in the understanding and teaching of the principles of aseptic technique, most likely due to lack of structured training. Educational initiatives are needed to correct these teaching gaps.

Ambulatory surgery adult patient selection criteria: a survey of Canadian anesthesiologists

PurposeAn increasing number of patients with complex medical problems are now considered suitable for ambulatory surgery. The purpose of this study was to identify the current clinical practice of ambulatory surgical patient selection.MethodsA standardized questionnaire specifying 30 clinical conditions was sent to all practicing anesthesiologists who are members of the Canadian Anesthesiologists’ Society. Recipients were asked to indicate if they would provide ambulatory anesthesia (yes/no answers) for an adult patient with each of those isolated conditions. A 75% agreement was considered a majority opinion.ResultsOne thousand three hundred thirty-seven questionnaires were sent and 774 replies were received (57.8%). Over 75% of anesthesiologists were willing to include in their selection criteria American Society of Anesthesiologists’ (ASA) physical status III, patients with low-grade angina pectoris (AP) and congestive heart failure (CHF), prior myocardial infarction, asymptomatic valvular disease, sleep apnea without use of narcotics, morbid obesity (MO) without co-morbidities, insulin dependent diabetes mellitus and malignant hyperthermia (MH) susceptible patients. Over 75% of responders found ASA IV patients, high grade AP and CHF, sleep apnea with postoperative narcotics, MO with co-morbidities and no patient escort to be unsuitable for ambulatory anesthesia.ConclusionOur survey demonstrated that medical conditions with extreme grades of severity (mild or severe) are associated with majority opinion to proceed or not to proceed with ambulatory surgery. Issues with over 75% agreement reflect the common practice. Similar surveys may form a part of patient selection guidelines development in the future.RésuméObjectifUn nombre croissant de patients ayant des problèmes médicaux complexes est maintenant admissible à la chirurgie ambulatoire. Nous avons voulu vérifier la pratique clinique courante de sélection des patients pour la chirurgie ambulatoire.MéthodeUn questionnaire normalisé présentant 30 conditions cliniques a été envoyé à tous les anesthésiologistes en exercice, membres de la Société canadienne des anesthésiologistes. Les répondants devaient indiquer par oui ou non s’ils offriraient une anesthésie ambulatoire à un patient adulte pour chacune de ces conditions isolées. Une adhésion à 75 % était considérée comme une opinion majoritaire.RésultatsNous avons reçu 774 réponses pour les 1 337 questionnaires envoyés, soit 57,8 %. Plus de 75 % des anesthésiologistes étaient disposés à inclure dans leurs critères de sélection des patients d’état physique III, selon l’American Society of Anesthesiologists (ASA), qui présentent une angine de poitrine (AP) d’évolution lente et une insuffisance cardiaque congestive (ICC), un infarctus du myocarde ancien, une valvulopathie asymptomatique, de l’apnée du sommeil sans usage de narcotiques, de l’obésité morbide (OM) sans comorbidités, un diabète insulino-dépendant et les patients susceptibles d’hyperthermie maligne peranesthésique. Au-delà de 75 % des répondants ont trouvé l’anesthésie ambulatoire inappropriée pour les patients ASA IV, les cas d’AP et d’ICC de haut degré, d’apnée du sommeil avec narcotiques postopératoires, d’OM avec comorbidités et pour les patients sans accompagnateur.ConclusionL’enquête démontre que pour les conditions médicales de sévérité extrême (modérée ou sévère) une majorité accepte ou n’accepte pas la chirurgie ambulatoire. Les enjeux qui recueillent plus de 75 % d’adhésion représentent la pratique courante. Ce type d’enquête pourrait faire partie de futures directives sur la sélection des patients.

Challenging authority during a life-threatening crisis: the effect of operating theatre hierarchy

BACKGROUND Effective operating theatre (OT) communication is important for team function and patient safety. Status asymmetry between team members may contribute to communication breakdown and threaten patient safety. We investigated how hierarchy in the OT team influences an anaesthesia trainees ability to challenge an unethical decision by a consultant anaesthetist in a simulated crisis scenario. METHODS We prospectively randomized 49 postgraduate year (PGY) 2-5 anaesthesia trainees at two academic hospitals to participate in a videotaped simulated crisis scenario with a simulated OT team practicing either a hierarchical team structure (Group H) or a non-hierarchical team structure (Group NH). The scenario allowed trainees several opportunities to challenge their consultant anaesthetist when administering blood to a Jehovahs Witness. Three independent, blinded raters scored the performances using a modified advocacy-inquiry score (AIS). The primary outcome was the comparison of the best-response AIS between Groups H vs NH. Secondary outcomes included the comparison of best AIS by PGY and the percentage in each group that checked and administered blood. RESULTS The AIS did not differ between the groups (P=0.832) but significantly improved from PGY2 to PGY5 (P=0.026). The rates of checking blood (92% vs 76%, P=0.082) and administering blood (62% vs 57%, P=0.721) were high in both groups but not significantly different between the groups. CONCLUSIONS This study did not show a significant effect of OT team hierarchical structure on trainees ability to challenge authority; however, the results are concerning. The challenges were suboptimal in quality and there was an alarming high rate of blood checking and administration in both groups. This may reflect lack of training in appropriately and effectively challenging authority within the formal curriculum with implications for patient safety.

Heart rate/blood pressure response and airway morbidity following tracheal intubation with direct laryngoscopy, GlideScope and Trachlight: a randomized control trial

Background and objective Haemodynamic response to tracheal intubation might be detrimental in high-risk patients. Minimizing oropharyngo-laryngeal stimulation or avoiding laryngoscopy may attenuate this response. We hypothesized that intubations performed with GlideScope or Trachlight would generate a lesser haemodynamic response than the conventional method of direct laryngoscopy. The objective of this study was to compare the haemodynamic response following tracheal intubation, using three different techniques of intubation. We also examined postoperative airway morbidities as our secondary outcome. Methods This was a prospective randomized control trial, conducted at Mount Sinai Hospital of Toronto. After Ethics Board approval, 60 adult ASA status I and II patients, scheduled for elective surgery requiring general anaesthesia with orotracheal intubation, were randomly allocated into three groups. Intubation was performed by a single experienced anaesthesiologist, using direct laryngoscopy, GlideScope or Trachlight. The haemodynamic variables were measured noninvasively at specific time intervals. We also recorded the number of attempts and total time for intubation. Postoperative airway symptoms following surgery were assessed using a questionnaire. Results There was no significant difference in blood pressure and heart rate between the groups. Direct laryngoscopy intubation times were significantly lower than those of the other techniques (both P < 0.0001). The occurrence of sore-throat symptoms in recovery was significantly higher in the Trachlight group (P = 0.0033). Conclusion There was no benefit of using any of the three intubation techniques for attenuation of haemodynamic changes. There was a higher incidence of airway symptoms associated with Trachlight intubation.

A comparison of lactated ringer's solution to hydroxyethyl starch 6% in a model of severe hemorrhagic shock and continuous bleeding in dogs.

In this randomized, controlled study in dogs, we examined the short-term effects of blood pressure targeted fluid resuscitation with colloids or crystalloids solutions on systemic oxygen delivery, and lactate blood concentration. Fluid resuscitation using hydroxyethyl starch (HES) 6% to a mean arterial blood pressure (MAP) of 60 mm Hg was compared with lactated Ringer’s solution (LR) to a MAP of 60 or 80 mm Hg (LR60 and LR80, respectively). The model was one of withdrawal of blood to a MAP of 40 mm Hg through an arterial catheter that was then connected to a system allowing bleeding to occur throughout the study whenever MAP exceeded 40 mm Hg. Target MAP was maintained for 60 min with a continuous infusion of the designated fluid replacement. All 15 dogs (5 in each group) survived until the last measurement. Blood loss in the LR80 group (2980 ± 503 mL) (all values mean ± sd) was larger than in the LR60 and HES60 groups (1800 ± 389 mL, and 1820 ± 219 mL, respectively) (P < 0.001). Whereas 840 ± 219 mL of HES60 was needed to maintain target MAP, 1880 ± 425 mL of LR was needed in the LR60 group, and 4590 ± 930 mL in the LR80 group (P < 0.001). Lactate blood concentrations were smaller and delivered O2 higher in the HES60 group (35 ± 17 mg/dL and 239 ± 61 mL/min, respectively) in comparison to the LR60 group (89 ± 18 mg/dL and 140 ± 48 mL/min, respectively) and the LR80 group (75 ± 23 mg/dL and 153 ± 17 mL/min, respectively) (P = 0.02 and P = 0.026). In conclusion, fluid resuscitation during uncontrolled bleeding, to a target MAP of 60 mm Hg, using HES60 resulted in larger oxygen delivery and smaller systemic lactate A resuscitation to a target MAP of 60 or 80 mm Hg using LR.