Janet van Vlymen

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.

Is the Bispectral Index Useful in Predicting Fast- Track Eligibility After Ambulatory Anesthesia with Propofol and Desflurane?

This study was designed to test the hypothesis that outpatients with higher electroencephalographic (EEG) Bispectral Index (BIS) values at the end of anesthesia achieve a modified Aldrete score of 10 and satisfy fast-track eligibility criteria more rapidly after ambulatory surgery. Sixty consenting women undergoing laparoscopic tubal ligation procedures were studied. After premedication with midazolam 2 mg IV, anesthesia was induced with propofol 2 mg/kg IV, fentanyl 1.5 [micro sign]g/kg IV, and succinylcholine 1 mg/kg IV and was initially maintained with either desflurane 4% (n = 31) or a propofol infusion 100 [micro sign]g [center dot] kg-1 [center dot] min-1 (n = 29), in combination with nitrous oxide 65% in oxygen. Subsequently, the inspired desflurane concentrations (2%-6%) and propofol infusion rates (50-150 [micro sign]g [center dot] kg-1 [center dot] min-1 were varied to maintain a clinically acceptable depth of anesthesia. The average BIS value during the 3-min interval immediately before the discontinuation of the maintenance anesthetics was recorded. Emergence times and modified Aldrete scores were assessed from the end of anesthesia until patients were considered fast-track-eligible. The BIS values at the end of anesthesia were significantly correlated with the time to reach fast-track eligibility in both the desflurane (r = -0.68) and propofol (r = -0.76) groups. We concluded that the EEG-BIS value at the end of anesthesia is useful in predicting fast-track eligibility after laparoscopic tubal ligation procedures with either a desflurane- or propofol-based anesthetic technique. Implications: In outpatients receiving either desflurane and propofol anesthesia for laparoscopic tubal ligation surgery, the times to achieve criteria for bypassing the recovery room (i.e., fast-tracking) correlated with the electroencephalo-graphic-Bispectral Index values at the end of anesthesia. (Anesth Analg 1998;87:1245-8)

Subdissociative‐dose Ketamine versus Fentanyl for Analgesia during Propofol Procedural Sedation: A Randomized Clinical Trial

OBJECTIVES The authors sought to compare the safety and efficacy of subdissociative-dose ketamine versus fentanyl as adjunct analgesics for emergency department (ED) procedural sedation and analgesia (PSA) with propofol. METHODS This double-blind, randomized trial enrolled American Society of Anesthesiology (ASA) Class I or II ED patients, aged 14-65 years, requiring PSA for orthopedic reduction or abscess drainage. Subjects received 0.3 mg/kg ketamine or 1.5 mug/kg fentanyl intravenously (IV), followed by IV propofol titrated to deep sedation. Supplemental oxygen was not routinely administered. The primary outcomes were the frequency and severity of cardiorespiratory events and interventions, rated using a composite intrasedation event rating scale. Secondary outcomes included the frequency of specific scale component events, propofol doses required to achieve and maintain sedation, times to sedation and recovery, and physician and patient satisfaction. RESULTS Sixty-three patients were enrolled. Of patients who received fentanyl, 26/31 (83.9%) had an intrasedation event versus 15/32 (46.9%) of those who received ketamine. Events prospectively rated as moderate or severe were seen in 16/31 (51.6%) of fentanyl subjects versus 7/32 (21.9%) of ketamine subjects. Patients receiving fentanyl had 5.1 (95% confidence interval [CI] = 1.9 to 13.6; p < 0.001) times the odds of having a more serious intrasedation event rating than patients receiving ketamine. There were no significant differences in secondary outcomes, apart from higher propofol doses in the ketamine arm. CONCLUSIONS Subdissociative-dose ketamine is safer than fentanyl for ED PSA with propofol and appears to have similar efficacy.

The effects of reversal of neuromuscular blockade on autonomic control in the perioperative period

Impaired parasympathetic control of heart rate is associated with increased incidence of cardiac dysrhythmias and ischemia.Anticholinergic drugs suppress parasympathetic control and could be detrimental in the early postoperative period in high-risk patients. In this double-blind randomized trial, 30 ASA physical status I and II patients undergoing minor surgery received either atropine 20 micro g/kg and neostigmine 50 micro g/kg (Group A), glycopyrrolate 8 micro g/kg and neostigmine 50 micro g/kg (Group G), or placebo (Group P) for reversal of neuromuscular blockade. Two indices of parasympathetic modulation of heart rate, spontaneous baroreflex sensitivity, and high-frequency heart rate variability, were assessed. At 2 h after reversal, Group A showed persisting impairment of baroreflex sensitivity with respect to Group P (7.12 +/- 0.86 vs 12.71 +/- 1.38 ms/mm Hg, P = 0.022) as well as decreased high-frequency heart rate variability (280.8 +/- 30.1 vs 569.2 +/- 115.2 ms2/Hz, P = 0.015). Groups A and G showed a borderline decrease in normalized high-frequency variability at 2 h (P = 0.05 for Groups A and G versus Group P). Anticholinergic drugs with neostigmine cause impairment of parasympathetic control of heart rate which persists into the early postoperative period. The effects of glycopyrrolate appear to be of shorter duration; this drug may thus be preferable in patients at risk of cardiovascular complications. (Anesth Analg 1997;84:148-54)

Post discharge nausea and vomiting after ambulatory laparoscopy is not reduced by promethazine prophylaxis

PurposeTo determine the incidence of post-discharge nausea and vomiting (PDNV) following outpatient laparoscopic procedures in women, and to assess the efficacy of the prophylactic administration of promethazine prior to discharge from hospital.MethodsNinety-five healthy women scheduled for ambulatory laparoscopic cholecystectomy or gynecological surgery completed this double blind, placebo controlled study. A standardized fentanyl-propofol-nitrous oxideisoflurane anesthetic was used, and all patients received 0.5 mg droperidoliv, intraoperatively. Subjects were randomized to receive 0.6 mg·kg−1 promethazine or placeboim prior to transfer from the post-anesthetic recovery (PAR) unit. The incidence and severity of nausea, pain, and drowsiness were documented using patient diaries at four time intervals during the first 24 hr postoperatively using four-point self-assessment scales.ResultsAfter discharge home, the overall incidence of nausea was 48%, moderate to severe nausea 30%, vomiting 17% and rescue antiemetic use 28%, with no difference between those receiving saline or promethazine. The need for antiemetics in the PAR was associated with subsequent PDNV with those requiring PAR antiemetics being four times as likely to vomit after discharge (P = 0.008).ConclusionDespite the prophylactic administration of 0.5 mg droperidoliv, patients undergoing ambulatory laparoscopic surgery reported a high incidence of nausea after discharge. Patients requiring antiemetics in the PAR were at higher risk for PDNV. The incidence of nausea was not altered by prophylactic administration of 0.6 mg·kg−1 promethazine im before discharge.RésuméObjectifDéterminer l’incidence de nausées et de vomissements postcongé (NVPC) après une laparoscopie ambulatoire et évaluer l’efficacité de l’administration prophylactique de prométhazine avant le départ de l’hôpital.MéthodeQuatre-vingt-dix femmes en santé, qui ont subi une cholécystectomie laparoscopique ou une intervention gynécologique, élective et ambulatoire, ont participé à une étude en double aveugle contre placebo. L’anesthésie était standard: fentanyl, propofol, protoxyde d’azote et isoflurane. Toutes les patientes ont reçu 0,5 mg de dropéridoliv peropératoire. Elles ont été réparties de façon aléatoire et ont reçu, soit 0,6 mg·kg−1 de prométhazine, soit un placeboim avant le transfert de la salle de réveil. L’incidence et la sévérité des nausées et des vomissements, de la douleur et de la somnolence ont été documentées en utilisant ce que les patientes ont noté à quatre reprises pendant les premières 24h postopératoires selon des échelles d’évaluation personnelle en quatre points.RésultatsAprès le congé, l’incidence globale de nausées a été de 48%; de nausées modérées ou sévères, 30%; de vomissements, 17% et de recours aux antiémétiques, 28%, sans différence intergroupe (placebovs prométhazine). La demande d’antiémétiques à la salle de réveil était associée aux NVPC subséquents, les patientes qui ont reçu ces antiémétiques étant quatre fois plus à risque de vomir après le départ de l’hôpital (P = 0,008).ConclusionMalgré l’administration prophylactique de 0,5 mg de dropéridoliv, les patientes qui subissent une opération laparoscopique ambulatoire ont rapporté une forte incidence de nausées après le congé de l’hôpital. Celles qui ont eu besoin d’antiémétiques à la salle de réveil étaient plus à risque de NVPC. L’incidence des nausées n’a pas été modifiée par l’administration prophylactique de 0,6 mg·kg−1 de prométhazineim avant le départ.

Use of the Intubating Laryngeal Mask Airway: Are Muscle Relaxants Necessary?

Background The intubating laryngeal mask airway (ILMA) is designed to facilitate blind tracheal intubation. The effect of a muscle relaxant on the ability to perform tracheal intubation through the ILMA device has not been previously evaluated. This randomized, double-blind, placebo-controlled study was designed to evaluate rocuronium, 0.2 or 0.4 mg/kg administered intravenously, on the success rate and incidence of complications associated with ILMA-assisted tracheal intubation. Methods A total of 75 healthy patients were induced with propofol 2 mg/kg and fentanyl 1 &mgr;g/kg intravenously. After insertion of the ILMA device, patients were administered either saline, rocuronium 0.2 mg/kg, or rocuronium 0.4 mg/kg in a total volume of 5 ml. At 90 s after administration of the study drug, tracheal intubation was attempted using a disposable polyvinyl tube. If unsuccessful, a reusable silicone tube was tried. In addition to recording the time and number of attempts required to secure the airway, the incidence of complications during placement of the tracheal tube and removal of the ILMA were noted. Results Tracheal intubation was successful in 76–96% of the patients. The overall success rates and times required to secure the airway were similar in all three treatment groups. The high-dose rocuronium group experienced less patient movement (8 vs. 28 and 48%) and coughing (12 vs. 20 and 52%) than the low-dose rocuronium and saline groups, respectively. Use of rocuronium was also associated with a dose-related decrease in the requirement for supplemental bolus doses of propofol during intubation and removal of the ILMA device. Conclusions Use of rocuronium did not significantly improve the success rate in performing tracheal intubation through the ILMA. However, it produced dose-related decreases in coughing and movement after tracheal intubation and reduced difficulties associated with removal of the ILMA device.

The duration of impairment of autonomic control after anticholinergic drug administration in humans

Impaired parasympathetic control of heart rate is associated with increased incidence of cardiac dysrhythmias and ischemia.Anticholinergic drugs, commonly administered during reversal of neuromuscular blockade, suppress parasympathetic control in the early postoperative period. This could potentially be detrimental in patients at risk of cardiovascular complications. The duration of parasympathetic impairment by two anticholinergic drugs were compared in this double-blind randomized cross-over study. Fourteen healthy volunteers received a single intravenous injection of atropine 20 micro g/kg or glycopyrrolate 8 micro g/kg during two different study sessions. The methods of spontaneous baroreflex analysis and spectral analysis of heart rate variability generated indices of beat-by-beat parasympathetic modulation of heart rate. Both drugs resulted in a marked decrease in baroreflex sensitivity and high-frequency heart rate variability. The times to return to baseline values were approximately doubled after atropine compared to glycopyrrolate (177 +/- 22 vs 82 +/- 8 min for baroreflex sensitivity, 212 +/- 16 vs 111 +/- 14 min for high-frequency power, and 171 +/- 18 vs 95 +/- 18 min for high-frequency power normalized to total power; P < 0.01 for all variables). Atropine leads to more prolonged impairment of parasympathetic control than equipotent doses of glycopyrrolate, and its use may thus be less desirable in high-risk patients in the early postoperative period. (Anesth Analg 1997;84:155-9)

Use of the cuffed oropharyngeal airway as an alternative to the laryngeal mask airway with positive-pressure ventilation

BACKGROUND The cuffed oropharyngeal airway is a modified Guedel-type oral airway with a cuff at its distal end. The objectives of this study were to compare the ability of the cuffed oropharyngeal airway and the laryngeal mask airway to provide positive-pressure ventilation during general anesthesia, and to assess their relative ease of use and ability to reduce total fresh gas flow rates. METHODS In this prospective, randomized study, a cuffed oropharyngeal airway (n = 25) or a laryngeal mask airway (n = 25) device was inserted after induction of anesthesia intravenously using 2 mg/kg propofol. While anesthesia was maintained with sevoflurane and nitrous oxide, the leak pressure, leak fraction (the fractional difference between the inspired and expired tidal volume), minimum fresh gas flow rate, and need for airway manipulations were determined. The anesthesia provider who inserted the device completed an evaluation form at the end of the 15-min study period. RESULTS Positive-pressure ventilation was established successfully on the first attempt in 92% of the patients when the cuffed oropharyngeal airway was used and in 88% of the patients when the laryngeal mask airway device was used. However, manipulations of the airway device were necessary more frequently (8 vs. 1 patient; P < 0.05) and the leak pressure was less (22 +/- 6 cm water vs. 26 +/- 5 cm water; P < 0.05) with the cuffed oropharyngeal airway than with the laryngeal mask airway. In addition, the leak fraction (0.19 +/- 0.18 vs. 0.31 +/- 0.22; P < 0.05) and the minimum fresh gas flow rate (1.3 +/- 1.5 vs. 2.4 +/- 2.5; P = 0.12) were less in the laryngeal mask airway group. CONCLUSIONS Positive-pressure ventilation is possible with the laryngeal mask airway and cuffed oropharyngeal airway devices. Although the cuffed oropharyngeal airway can be inserted easily by inexperienced users with a high first-attempt success rate (> 90%), manipulations of the device may be required to maintain a patent airway. The laryngeal mask airway device allows positive-pressure ventilation at slightly greater peak inspiratory pressures.

The methylene blues : anticipating adverse reactions to non-anesthetic drugs

NE of the main focuses in the training of anesthesiologists is the art of applied clinical pharmacology. The many and diverse drugs that we use daily have near instantaneous actions, satisfying the need for “immediate gratification” that attracted many of us to this field. We are also well trained in anticipating and treating the unintended effects of our pharmacologic armamentarium. These range from common side effects such as hypotension or hypoventilation, to sporadic reactions such as anaphylaxis. To complicate matters, the incidence of adverse drug reactions is influenced by factors such as age, ethnicity, pre-existing medical conditions and concurrent drug therapy. For example, we can predict that elderly, diabetic or hypertensive patients may have an exaggerated blood pressure response to induction agents, or that angiotensin converting enzyme inhibitor and beta adrenergic blocking drugs may alter the hemodynamic response to anesthetics. In this way, we constantly anticipate reactions and tailor our anesthetic techniques to account for these factors. Similarly, many patients present with a history of allergic reactions to medications; these drugs can easily be avoided. We can also predict a higher incidence of such reactions in patients with other known sensitivities, such as the increased incidence of reactions to non-steroidal anti-inflammatory drugs (NSAIDs) in patients with allergy to aspirin, 1 or an alteration in response to meperidine in patients receiving monoamine oxidase inhibitors. 2 A family history of malignant hyperthermia or cholinesterase deficiency prompts special precautions due to the known genetic transmission of these traits. Frequently, it is not the drug compound that is responsible for reactions, but rather preservatives in the preparations, such as local anesthetics with the preservatives methylparaben in patients with a history of sunscreen allergy, and sodium metabisulfite in patients with sulfite allergy. 3 There is, however, an increasing demand on the anesthesiologist to administer (and thereby assume responsibility for) a variety of non-anesthetic drugs. In addition, drugs, or other potential allergens such as disinfectant preparations, are frequently administered by surgeons and nurses, with the expectation that the “resuscitation expert” at the head of the table will deal with any potential reactions. A list of commonly used agents that fall into this category is provided in the Table; this list is not comprehensive, and there are new drugs with potential reactions being added almost daily.

Managing the perioperative patient on direct oral anticoagulants

PurposePatients are increasingly treated with direct oral anticoagulants (DOACs) for the prevention of stroke due to non-valvular atrial fibrillation and for the treatment of venous thromboembolism. When these patients present for urgent or emergent surgical procedures, they present a challenge to the anesthesiologist who must manage perioperative risk due to anticoagulation. The purpose of this module is to review the literature surrounding the perioperative management of DOACs. Timing, laboratory monitoring, and availability of reversal agents are important considerations to optimize patients being treated with DOACs who require emergent surgery.Principal findingsLaboratory tests are not recommended for routine monitoring of DOACs since they do not correlate well with anticoagulant activity. Most widely available laboratory tests lack the sensitivity to detect anticoagulant effects at low plasma concentrations. However, a normal thrombin time for dabigatran excludes clinically significant drug levels. If the risk of bleeding is judged to be high because of a recent dose of DOAC, various options are available to mitigate bleeding. When possible, surgery should be delayed for at least 12 hr after the last dose of DOAC. Activated charcoal may mitigate the anticoagulant effect caused by DOACs if administered less than two hours after the drug was ingested. Four-factor prothrombin complex concentrates (PCCs) may be useful to reduce life-threatening bleeding associated with factor Xa inhibitors. Activated PCCs have been shown to reverse abnormal coagulation tests associated with all DOACs, but there is a lack of reported evidence of clinical benefit. Idarucizumab is a specific antidote that is effective for reversal of anticoagulation due to dabigatran. An antidote for rivaroxaban and apixaban (andexanet alfa) as well as a universal antidote for all DOACs and heparin (PER977) are in clinical development.ConclusionPerioperative management of anticoagulation due to DOACs is a growing concern as the number of patients prescribed these medications increases each year. These patients can be safely optimized for urgent or emergent surgery by giving appropriate consideration to timing, monitoring, and reversal agents.RésuméObjectifLes patients sont de plus en plus souvent traités à l’aide d’anticoagulants oraux directs (AOD), autrefois appelés nouveaux anticoagulants oraux (ou NACO), que ce soit pour prévenir les accidents vasculaires cérébraux provoqués par une fibrillation auriculaire non valvulaire ou pour le traitement des thromboembolies veineuses. Lorsque ces patients se présentent pour subir une intervention chirurgicale urgente ou très urgente, l’anesthésiologiste se retrouve souvent face à une situation difficile car il doit gérer le risque périopératoire provoqué par l’anticoagulant. L’objectif de ce module est de passer en revue la littérature abordant la prise en charge périopératoire des AOD. Le moment choisi pour l’administration, le monitorage et la disponibilité des antidotes sont d’importantes considérations lorsqu’il faut prendre en charge de façon optimale les patients traités à l’aide d’AOD et nécessitant une chirurgie très urgente.Constatations principalesLes analyses de laboratoire ne sont pas recommandées pour le monitorage de routine des AOD étant donné que leur corrélation à l’activité anticoagulante n’est pas très élevée. Les essais de laboratoire les plus répandus ne disposent pas de la sensibilité suffisante pour détecter des effets anticoagulants à de faibles concentrations plasmatiques. Toutefois, si un temps de thrombine normal est observé pour le dabigatran, cela exclut des taux médicamenteux significatifs d’un point de vue clinique. Si le risque de saignement est estimé comme étant élevé en raison de l’administration récente d’une dose d’AOD, diverses options existent pour mitiger le saignement. Lorsque cela est possible, la chirurgie devrait être retardée d’au moins 12 h après la dernière dose d’AOD. Le charbon activé pourrait mitiger l’effet anticoagulant provoqué par les AOD s’il est administré moins de deux heures après l’ingestion du médicament. Les concentrés de complexe prothrombique (CCP) contenant quatre facteurs peuvent être utiles pour réduire les saignements potentiellement fatals associés aux inhibiteurs du facteur Xa. Il a été démontré que les CCP activés neutralisaient les tests de coagulation anormaux associés à tous les AOD, mais les données probantes rapportant un bienfait clinique font encore défaut. L’idarucizumab est un antidote spécifique efficace pour neutraliser l’anticoagulation provoquée par le dabigatran. Un antidote du rivaroxaban et de l’apixaban (andexanet alfa) ainsi qu’un antidote universel des AOD et des héparines (PER977) sont en cours de développement clinique.ConclusionLa prise en charge périopératoire de l’anticoagulation provoquée par les AOD est une préoccupation croissante étant donné l’augmentation annuelle du nombre de patients auxquels ces médicaments sont prescrits. Ces patients peuvent être pris en charge de façon sécuritaire et optimale pour toute chirurgie urgente ou très urgente en évaluant soigneusement le moment choisi, le monitorage et les antidotes.