Steven L. Dain

Anaesthesia for adenotonsillectomy: a comparison between tracheal intubation and the armoured laryngeal mask airway

A prototype armoured laryngeal mask airway (LMA) was compared with tracheal intubation (ETT) for anaesthesia for adenotonsillectomy. Fifty-five children were randomised into the LMA group and 54 into the ETT group. During insertion of the LMA, peripheral oxyhaemoglobin desaturation (SpO2) < 94% occurred in ten patients (18.2%) and in seven patients (13%) during tracheal intubation (NS). After opening the Boyle-Davis gag, airway obstruction occurred in ten patients (18.2%) in the LMA group and in three patients (6%) in the ETT group (P = 0.07). In five patients (9%) the LMA was abandoned in favour of tracheal intubation. In all others (91%), when the need for adequate depth of anaesthesia was realized, a satisfactory airway was achieved more rapidly than with tracheal intubation (P < 0.001), and maintained throughout surgery. Manually assisted ventilation was required in all patients in the ETT group, mean duration 373 ± 385 sec, and in 26 patients (52%) in the LMA group, mean duration 134 ± 110 sec, P < 0.001. Mean end-tidal CO2 (PetCO2) was 45.5 ± 6.21 mmHg in the ETT group and 46.6 ± 6.09 in the LMA group (NS). The LMA did not limit surgical access. Heart rate, MAP and blood loss in the LMA group were 110 ± 21, 74 ± 9 mmHg and 1.92 ± 1.22 ml · kg−1 respectively, compared with 143 ± 13 (P < 0.001), 85 ± 12 mmHg (P < 0.001) and 2.62 ± 1.36 ml · kg−1 (P < 0.05) with tracheal intubation. Fibreoptic laryngoscopy at the end of surgery in 19 patients in the LMA group revealed no blood in the larynx. In the LMA group postintubation stridor and laryngospasm occurred in five and three patients respectively, compared with 14 (P < 0.05) and six patients respectively (NS) with tracheal intubation. SpO2 on admission to the PACU in the LMA group was 95.9 ± 2.21, and 93.5 ± 4.53 (P < 0.05) after tracheal intubation. Our study demonstrated that the LMA is a safe alternative to tracheal intubation for adenotonsillectomy. Control of airway reflexes by ensuring sufficient depth of anaesthesia is essential for successful use of the LMA in children.RésuméUn prototype de masque larngyé armé (ML) est comparé à l’intubation trachéale (TE) pendant l’anesthésie pour adéno-amygdalectomie. Cinquante-cinq enfants sont assignés au hasard au groupe ML et 54 au groupe TE. Pendant l’insertion du ML, une désaturation périphérique inférieure à 94% survient chez dix patients (18,2%) et pendant l’intubation trachéale chez sept patients (13%) (NS). Après la mise en place de l’ouvre-bouche de Boyle-Davis, l’obstruction des voies aériennes supérieures survient chez dix patients (18,2%) dans la groupe ML et trois patients dans le groupe TE (P = 0.07). Chez cinq patients (9%), on abandonne le ML en faveur de l’intubation trachéale. Chez tous les autres (91%), après l’atteinte d’un niveau d’anesthésie adéquat, un airway satisfaisant est réalisé plus rapidement qu’avec l’intubation trachéale (P < 0,001) et maintenu pendant la chirurgie. Une ventilation assistée manuellement devient nécessaire pour tous les patients du groupe TE, avec une durée moyenne de 373 ± 385 sec, et chez 26 patients (52%) du groupe ML, avec une durée moyenne de 134 ± 110 sec (P < 0,001). Le CO2 télé-expiratoire (PetCO2) est de 45,5 ± 6,21 mmHg dans le groupe TE et de 46,6 ± 6,09 mmHg dans le groupe MLA (NS). Le MLA ne limite pas l’accès chirurgical. La fréquence cardiaque, la PAM et la perte sanguine est de 110 ± 21, 74 ± 9 mmHg et 1,92 ± 1,22 ml · kg−1 respectivement pour le groupe ML, comparativement à 143 ± 13 (P < 0,001), 85 ± 12 mmHg (P < 0,001) et 2,62 ± 1,36 ml · kg−1 (P < 0,05) pour le groupe TE. Chez 19 patients du groupe ML, la fibroscopie à la fin de la chirurgie n’a pas révélé la présence de sang dans le larynx. Dans le groupe ML après l’intubation, un stridor et un laryngospasme sont apparus chez cinq et trois patients respectivement, comparativement à 14 (P < 0,05) et six patients respectivement (NS) dans le groupe TE. Notre étude montre que le ML est une alternative sécuritaire à l’intubation trachéale pour l’adéno-amygdalectomie. Pour utiliser avec succès la LM, il est essentiel de contrôler les réflexes des voies aériennes par une anesthésie suffisamment profonde.

Anesthesia for Intranasal Surgery: A Comparison Between Tracheal Intubation and the Flexible Reinforced Laryngeal Mask Airway

UNLABELLED The purpose of the study was to assess the suitability and safety of the flexible reinforced laryngeal mask airway (FRLMA) for intranasal surgery (INS) anesthesia. A secondary objective was to compare the incidence of complications of removal of the FRLMA with tracheal extubation in awake and anesthetized patients. One hundred fourteen ASA physical status I and II patients requiring INS were randomly assigned into three groups: Group I = FRLMA, Group II = endotracheal tube (ET) extubated awake, and Group II = ET extubated deeply anesthetized. In Group I, the incidence of coughing and oxyhemoglobin desaturation at removal was significantly reduced compared with that in Groups II and III (P < 0.05). There were no episodes of postremoval laryngospasm in Group I; in Group III, the incidence was 19% (P < 0.05), whereas in Group II, it was 6% (not significantly different). The number of patients with oxyhemoglobin desaturation < or = 92% on admission to the postanesthesia care unit was 0% in Group I, 26% in Group II (P < 0.05), and 16% in Group III (not significantly different). At bronchoscopy, the incidence of blood visible in the airway was low and similar among the three groups (3%, 6%, and 3%, respectively). There were no significant differences in the incidence of airway complications between Groups II and III. IMPLICATIONS We compared airway management for intranasal surgery anesthesia using a new device, the flexible reinforced laryngeal mask airway, with the current standard of tracheal intubation. The study demonstrates that the flexible reinforced laryngeal mask airway can provide a safe, protected airway with a smoother emergence from anesthesia than tracheal intubation.

Brief review: perioperative management of the patient with chronic non-cancer pain.

PurposeBoth opioid and non-opioid medications are being utilized increasingly in the treatment of chronic non-cancer pain, and the number of surgical patients receiving large regular doses of opioids is ever-expanding. The perioperative pain control of these patients is often challenging, and is broadening the role of the anesthesiologist as ‘perioperative physician’. These patients need to be identified before surgery to plan optimal pain control postoperatively. The purpose of this review is to provide an update on the important considerations in managing the chronic non-cancer pain patient receiving high dose opioids and other adjunctive medications/analgesics.SourceEnglish language articles published between June 1980 and May 2006 were identified by a computerized Medline search using keywords “chronic pain”, “opioid dependent” and “perioperative”. This same search strategy was repeated and updated using both Medline and Embase. All relevant publications were retrieved and their bibliographies were scanned for additional sources.Principal findingsAlthough an increasingly common problem for the acute pain service, there is very little published on this topic. Key points include the concept of opioid equivalency, tolerance, the role of adjunctive medications, and the need for good communication between the surgical team, the acute pain service and the patient who is often anxious about the upcoming procedure due to previous unpleasant experiences with poor pain control in hospital.ConclusionClinical care of the opioid-dependent patient in the perioperative period can be a daunting task. Education to all staff involved in this area needs to be enhanced to improve outcome and patient satisfaction.RésuméObjectifOn traite de plus en plus les douleurs non cancéreuses avec des substances opiacées ou non opiacées et, en chirurgie, on retrouve un nombre croissant de patients prenant de fortes doses d’opiacés. Dans ce contexte, la prise en charge de la douleur représente souvent un défi et contribue au rôle grandissant de l’anesthésiologiste en « médecine périopératoire ». Ces patients doivent être identifiés avant la chirurgie pour planifier la prise en charge de la douleur en période postopératoire. l’objectif de cet article est de mettre à jour les éléments importants dans la prise en charge de la douleur non cancéreuse chez les patients qui reçoivent des doses élevées d’opiacés et d’autres médicaments/analgésiques adjuvants.SourceLes articles publiés en langue anglaise de juin 1980 et mai 2006 ont été identifiés grâce à une recherche informatisée dans Medline avec les mots-clés « chronic pain », « opiod dependent » et « perioperative ». La même stratégie de recherche a été répétée et mise à jour avec Medline et Embase. Toutes les publications ont été retrouvées et leur liste de références a été fouillée pour repérer des documents additionnels.Constatations principalesMême s’il s’agit d’un problème fréquent pour les services de douleur aiguë, il y a peu de publications sur ce sujet. Les thèmes principaux sont le concept d’équivalence pour les opiacés, la tolérance et le rôle des médicaments adjuvants. On retrouve aussi l’importance de la communication entre l’équipe chirurgicale, le service de douleur aiguë et le patient, qui est souvent inquiet de la chirurgie annoncée à cause d’expériences antérieures déplaisantes à l’hôpital où la prise en charge de la douleur laissait à désirer.ConclusionLes soins cliniques aux patients avec une dépendance aux opiacés peut constituer une tâche décourageante en période périopératoire. La formation des intervenants dans ce domaine doit être développée pour améliorer le pronostic et la satisfaction du patient.

Technical communication: the effect of the double mask on anesthetic waste gas levels during pediatric mask inductions in dental offices.

A significant portion of office-based general anesthesia for pediatric patients is performed in dental offices and involves mask inductions with inhaled drugs. This can lead to significant pollution with waste gases. We assessed occupational exposure to anesthetic drugs during pediatric general anesthesia in dental offices and assessed the effectiveness of the “double mask.” Nine freestanding dental offices had measurements of anesthetic waste gas levels taken before and immediately after implementation of a double-mask system. Levels of nitrous oxide decreased from a median of 40.0 parts per million (ppm; interquartile range [IQR] = 23.0–46.0 ppm, n = 9) to 3.0 ppm, (IQR = 2.3–4.7 ppm, n = 9, P = 0.0055) and exceeded 25 ppm in 0% of the 9 offices (upper 95% confidence limit 34%) when using the double mask. Levels of sevoflurane decreased from a median of 4.60 ppm (IQR = 3.10–7.00 ppm, n = 9) to 0 ppm (IQR = 0–0.39 ppm, n = 9, P = 0.0024) and exceeded 2 ppm in 0% of the 9 offices (upper 95% confidence limit 34%) when using the double mask. We demonstrated in our study that the double-mask system, when used with dental “high-volumes” suctions (high-volume evacuators producing approximately 12 m3/h) in freestanding dental offices, was sufficient to decrease the exposure to anesthetic waste gas during pediatric mask induction in at least two thirds of offices when compared with the traditional mask.

Towards international standardization of the anesthesia machine

THE practice of anesthesia and critical care has become increasingly dependent on medical technology. Almost every day we read articles in journals and newspapers and view on television some aspect of patient safety. It’s a trendy topic. Much is written on the fact that we must improve patient safety, but what is really being done about it? We have evolved from the old anesthesia machine which was a hodge-podge assembly of separate components, a Fluotec Mark II vaporizer, Ventimeter ventilator, Dial-a-Flo mixer, oxygen analyzer, low pressure alarm, one-channel electrocardiogram monitor, a manual mercury blood pressure cuff and stethoscope that was bolted together by a handyman in the basement of the hospital. We now have integrated anesthetic gas delivery and monitoring systems and in the future, the automated anesthesia glass cockpit. The term “standardization” when used in the context of making all equipment similar in design and function is really nowadays a misnomer. It’s just a small part of what medical equipment standards writers consider when writing a “standard”. What we are really trying to do is to write the minimum requirements for the “basic safety and essential performance” or in other words minimum engineering specifications for medical equipment in general; or for a particular device. Why the minimum, you may ask? Published standards must be sufficiently flexible to provide enough latitude to promote innovation. Standards that require the addition of numerous safety features increase the complexity of a device which may render the device unusable or more prone to failure. The law of diminishing returns takes over once again. An overview of standards development process has been published previously.1 There is no longer just one safety standard for the “anesthesia machine”, but a family of safety standards for almost every component of the “anesthesia system.”A In addition to the “particular” anesthesia system standard,B there are also additional standards covering radio frequency interference,C software, usabilityD and alarm systems.E Jeffrey Cooper in his classic article originally published in 1978 and reprinted in 2002 in the journal Quality and Safety in Health Care2 pointed out that only 14% of critical incidents in anesthesia were related to equipment failure, but 84% of preventable incidents were due to human error. Usability refers to the qualities of a device whereby it is easy to learn, easy to remember, and requires as few steps as possible to perform a task. Usability also implies that the system should have a low error rate and if errors are made, they should be easy to recognize and easy to fix. The device should be pleasant to use and should not frustrate or annoy the user. EDITORIAL 613

Teaching residents out-of-hospital anesthesia: what are we waiting for?

To the Editor, Out-of-hospital anesthesia is a rapidly growing field with up to 55% of all ambulatory procedures in the US currently being performed outside the hospital. In Canada, this practice includes anesthesia in non-hospital surgical facilities, out-of-hospital premises (OHPs), and various office settings (office-based anesthesia), some of which – depending on provincial regulations – may be regulated or accredited. An article reviewing this topic was recently published in the Journal. Teaching in large tertiary care hospitals may not prepare trainees adequately for out-of-hospital anesthesia that requires different knowledge and practice. The Association of Canadian University Departments of Anesthesia (ACUDA) is developing a national ambulatory curriculum; however, the program does not include specific consideration or mention of out-of-hospital anesthesia and its particular aspects of facility administration and patient care considerations in the preintraor postoperative phase (personal communication). In order to assess the need for an expanded curriculum, we sought to evaluate 1) the current training of Canadian anesthesia residents and 2) their knowledge of out-ofhospital anesthesia. Both portions of the study were approved by the primary author’s Hospital Research Ethics Board. During the first phase of our study, we asked the 16 directors of the Canadian training programs who were in attendance at the June 2009 ACUDA meeting to complete a previously published survey questionnaire that was designed to provide information regarding their programs’ educational activities and the exposure of their residents to out-ofhospital anesthesia. The response rate for the ACUDA survey was 14/16 (87%). Six (43%) of the 14 programs (95% confidence interval [CI], 34-52%) provided some services outside of hospitals, but only four (29%) of the 14 departments (95% CI, 21-37%) occasionally provided experience for their residents. Eleven (79%) of the 14 departments (95% CI, 71-87%) had no educational activities, and 12 (86%) departments (95% CI, 80-92%) had no formal rotation for out-of-hospital anesthesia. During the second phase of our study, we developed a ten-item test questionnaire that was validated by four experts in out-of-hospital ambulatory anesthesia using the Delphi method. The questionnaire was designed to assess knowledge about topics relevant to out-of-hospital anesthesia. It entailed written responses to questions on fire and electrical safety, management of malignant hyperthermia, control of infection, delegation of care, facility regulation, discharge criteria, and considerations for various pertinent clinical scenarios (e.g., obesity, obstructive sleep apnea, pediatrics, and thromboprophylaxis). The responses were scored by two independent raters who had not been M. M. Kurrek, MD (&) F. Chung, MD University of Toronto, Toronto, ON, Canada e-mail: m.kurrek@utoronto.ca