Shinichi Kihara

Segmental cervical spine movement with the intubating laryngeal mask during manual in-line stabilization in patients with cervical pathology undergoing cervical spine surgery.

We quantified the extent and distribution of segmental cervical movement produced by the intubating laryngeal mask (ILM) during manual in-line stabilization in 20 anesthetized patients with cervical pathology undergoing cervical spine surgery. All patients had neurological symptoms preoperatively. The ILM was inserted with the head and neck in the neutral position. Intubation was facilitated by transillumination of the neck with a lightwand. Cervical movement was recorded with single-frame lateral radiographic images taken 1) immediately before induction (baseline); 2) during ILM insertion (insertion); 3) when transillumination was first seen at the cricothyroid membrane (intubation A); 4) when the tube was being advanced into the trachea (intubation B); and 5) during ILM removal (removal). Radiographic images were digitized and the degree of flexion/extension and posterior movement measured for the occiput (C0) through to C5. During ILM insertion, C0-5 were flexed by an average of 1–1.6 degrees (all P < 0.05). During intubation A/B, C0-4 were flexed by an average of 1.4–3.0 degrees (all P < 0.01), but C5 was unchanged. During ILM removal, C0-3 were flexed by an average of 1 degree (all:P < 0.05), but C3-5 were unchanged. During insertion and intubation A/B, C2-5 were displaced posteriorly by an average of 0.5–1.0 mm (all:P < 0.05). During removal, there was no change at C1-5. Neurological symptoms improved in all patients. We conclude that the ILM produces segmental movement of the cervical spine despite manual in-line stabilization in patients with cervical spine pathology undergoing cervical spine surgery. This motion is in the opposite direction to direct laryngoscopy, suggesting that different approaches to airway management may be more appropriate depending on the nature of the cervical instability. Implications The intubating laryngeal mask produces segmental movement of the cervical spine, despite manual in-line stabilization in patients with cervical spine pathology undergoing cervical spine surgery. This motion is in the opposite direction to direct laryngoscopy, suggesting that different approaches to airway management may be more appropriate depending on the nature of the cervical instability.

Influence of Nitrous Oxide on Minimum Alveolar Concentration of Sevoflurane for Laryngeal Mask Insertion in Children

Background Inhalational induction with sevoflurane and nitrous oxide is frequently used for Laryngeal Mask Airway ™ (LMA ™; Laryngeal Mask Company, Henley-on-Thames, United Kingdom) insertion in children. The authors determined the influence of nitrous oxide on the minimum alveolar concentration (MAC) of sevoflurane for LMA ™ insertion. Methods One hundred twenty unpremedicated children (age, 1–9 yr; American Society of Anesthesiologists physical status I) were randomly assigned to receive 1 of 15 end-tidal concentrations of nitrous oxide and sevoflurane for inhalational induction via a facemask: 0% nitrous oxide with 1.2, 1.4, 1.6, 1.8, or 2.0% sevoflurane; 33% nitrous oxide with 0.8, 1.0, 1.2, 1.4, or 1.6% sevoflurane; or 67% nitrous oxide with 0.4, 0.6, 0.8, 1.0, or 1.2% sevoflurane. The LMA ™ was inserted after steady state end-tidal anesthetic concentrations had been maintained for 15 min. The response to insertion was recorded by three independent blinded observers. The interaction between nitrous oxide and sevoflurane was determined using logistic regression analysis. Results The MAC of sevoflurane for LMA ™ insertion (95% confidence limit) was 1.57% (1.42–1.72%), and the concentration of sevoflurane required to prevent movement in 95% of children was 1.99% (1.81–2.57%). The addition of 33% and 67% nitrous oxide linearly decreased the MAC of sevoflurane for LMA ™ insertion by 22% and 49%, respectively (P < 0.001). The interaction coefficient between nitrous oxide and sevoflurane did not differ from zero (P = 0.7843), indicating that the relation was additive. Conclusions Nitrous oxide and sevoflurane suppress the responses to LMA ™ insertion in a linear and additive fashion in children.

The awakening concentration of sevoflurane in children.

UNLABELLED Sevoflurane is frequently used as a rapidly acting drug for the induction of anesthesia. We investigated the awakening concentration (MAC-awake) of sevoflurane in ASA physical status I children (age range 2-10 yr). We also investigated the effects of two different doses of clonidine (2 and 4 microg/kg) on the MAC-awake of sevoflurane. Subjects were randomly divided into three groups and received placebo (n = 24), clonidine 2 microg/kg (n = 17), or clonidine 4 microg/kg (n = 22) orally, 100 min before the induction of anesthesia. Sedation scores were estimated, by using a five-point scale, after entry into the operating room, and anesthesia was induced and maintained with sevoflurane in oxygen and balanced nitrogen, without an additional anesthetic. After surgery, end-tidal sevoflurane was decreased stepwise by 0.2% at 15-min intervals, a standardized verbal command was played to the patients, and the MAC-awake was determined. The MAC-awake of sevoflurane alone was 0. 78% +/- 0.24% (mean +/- SD), which decreased to 0.36% +/- 0.09% and 0.36% +/- 0.16% (both P <0.0001, compared with the control group) after premedication with the small and large doses of clonidine, respectively. The lack of any dose-response relationship might be explained by a plateau effect. IMPLICATIONS The awakening concentration of sevoflurane in unpremedicated children was 0.78%. Oral clonidine premedication at a dose of 2 microg/kg reduced the awakening concentration to 0.36%. However, an additional decrease in this value was not observed after the administration of the larger dose of clonidine premedication (4 microg/kg).

The StyletScope is a better intubation tool than a conventional stylet during simulated cervical spine immobilization.

PurposeWe compare the StyletScope™ fibreoptic stylet (FOS) and the Satin Slip™ conventional metal stylet (CMS), during simulated difficult airway management with manual-in-line stabilization in terms of ease of intubation and esophageal intubation.Methods193 patients (ASA I-II, 18–80 yr) were studied in a noncrossover, randomized fashion. Manual-in-line stabilization was applied and the best laryngoscopic view obtained. For the CMS, the primed tracheal tube was advanced under direct vision if Cormack-Lehane grade 1/2, placed behind the epiglottis and advanced blindly if grade 3, and intubation was not attempted if grade 4. For the FOS, the primed tracheal tube was advanced under the direct vision if grade 1/2 and under fibreoptic vision if grade 3/4.ResultsIntubation was successful more frequently (P = 0.02) and required fewer attempts (P = 0.003) with the FOS than the CMS. Intubation with the FOS was successful more frequently (P = 0.02) and required fewer attempts (P = 0.007) than the CMS if grade 3/4. For both stylets, intubation required fewer attempts (P < 0.007) and was quicker (P < 0.0001) for grade 1/2 than 3/4. Esophageal intubation occurred more frequently with the CMS (14 vs 0,P = 0.0001).ConclusionTracheal intubation is more successful, requires fewer attempts and esophageal intubation is less frequent with the FOS than the CMS during cervical spine immobilization using manual-inline axial stabilization. The FOS is a more effective intubation instrument compared to the CMS in patients with simulated cervical spine immobilization.RésuméObjectifComparer le stylet fibroscopique (SFS) StyletScope ™ et le stylet de métal traditionnel (SMT) Satin Slip™, pour la simulation d’un contrôle difficile des voies aériennes avec stabilisation manuelle en ligne quant à la facilité d’intubation et à l’intubation œsophagienne.MéthodeL’étude randomisée, non croisée, a porté sur 193 patients (ASA I–II, 18–80 ans). On a appliqué la stabilisation en ligne et obtenu la meilleure vue laryngoscopique. Pour le SFS, le tube endotrachéal amorcé a été avancé sous vision directe avec un grade de Cormack-Lehane de 1/2, placé derrière l’épiglotte et avancé à l’aveugle avec un grade 3 et l’intubation n’a pas été tentée avec un grade 4. Pour le SMT, le tube a été avancé sous vision directe avec un grade 1/2 et sous vision fibroscopique avec un grade 3/4.RésultatsL’intubation a été réussie plus souvent (P = 0,02) et a demandé moins d’essais (P = 0,003) avec le SFS qu’avec le SMT. Avec un grade 3/4, l’intubation avec le SFS a été réussie plus souvent (P = 0,02) et avec moins d’essais (P = 0,007) qu’avec le SMT. Pour les deux stylets, l’intubation a nécessité peu d’essais (P < 0,007) et a été plus rapide (P < 0,0001) pour un grade 1/2 qu’un grade 3/4. L’intubation œsophagienne est survenue plus souvent avec le SMT (14 vs 0, P = 0,0001).ConclusionL’intubation trachéale réussit mieux et en moins d’essais, et l’intubation œsophagienne est moins fréquente, avec le SFS qu’avec le SMT lors de l’immobilisation de la colonne cervicale réalisée avec la stabilisation axiale manuelle en ligne. Le SFS, comparé au SMT, est plus efficace pour l’intubation en cas d’immobilisation simulée de la colonne cervicale.

Sex-based ProSeal laryngeal mask airway size selection: a randomized crossover study of anesthetized, paralyzed male and female adult patients.

We compared the Size 4 and 5 ProSeal™ laryngeal mask airway (PLMA™) in men and the Size 3 and 4, and 4 and 5 PLMA™ in women in terms of 1) ease of insertion, 2) oropharyngeal leak pressure (OLP), 3) ease of ventilation at a tidal volume of 10 mL/kg, 4) gas exchange, 5) location of gas leak, 6) anatomic position of the airway and drain tube, and 7) mucosal injury. Thirty male and 60 female (ASA physical status I–II; 18–80 yr old) anesthetized, paralyzed patients were studied in a crossover fashion in three equal-sized groups. PLMA™ insertion was performed by a single experienced operator by using digital manipulation. In male patients comparing the Size 4 and 5, OLP was higher (P = 0.0002) and leak fraction lower (P = 0.03) for the Size 5, but the number of insertion attempts, insertion time, mucosal injury, anatomic position, gas exchange, and location of gas leak were similar. In female patients comparing the Size 4 and 5 PLMA™, OLP was higher for the Size 5 (P < 0.0001), but the number of insertion attempts was fewer (P = 0.02), insertion time was quicker (P = 0.02), and there was less mucosal injury (P = 0.01) with the Size 4. There were no differences in anatomic position, gas exchange, or location of gas leak. In female patients comparing the Size 3 and 4 PLMA™, OLP was higher (P = 0.0005) and leak fraction was lower (P = 0.03) for the Size 4, but the number of insertion attempts, insertion time, mucosal injury, anatomic position, gas exchange, and location of gas leak were similar. There were no episodes of failed oxygenation, failed ventilation, or gastric insufflation. We conclude that if size is selected by sex, the Size 4 PLMA™ is preferable for women and the Size 5 PLMA™ for men.

Intraoperative transesophageal echocardiography for inferior vena caval tumor thrombus in renal cell carcinoma

Background : We investigated the advantages of intraoperative transesophageal echocardiography (TEE) during inferior vena caval tumor thrombectomy in renal cell carcinoma (RCC).

A comparison of sex- and weight-based ProSeal laryngeal mask Size selection criteria: A randomized study of healthy anesthetized, paralyzed adult patients

Background:The authors compared the manufacturer’s weight-based formula (size 3 for weight < 50 kg, size 4 for weight 50–70 kg, and size 5 for weight > 70 kg) with a sex-based formula (size 4 for women and size 5 for men) for selecting the appropriate size of ProSeal™ laryngeal mask airway. Methods:Two hundred thirty-seven healthy, anesthetized, paralyzed adult patients (American Society of Anesthesiologists physical status I or II; age, 18–80 yr) were randomly allocated for weight- or sex-based size selection. An experienced user inserted the ProSeal™ laryngeal mask airway with the digital technique. The following were compared: ease of insertion, oropharyngeal leak pressure, ease of ventilation, gas exchange, location of gas leak, anatomic position, mucosal injury, and postoperative pharyngolaryngeal problems. Intraoperative and postoperative data collection were unblinded and blinded, respectively. Results:Ease of insertion, anatomic position, gas exchange, mucosal injury, and postoperative pharyngolaryngeal problems were similar between groups. For the sex-based group, larger ProSeal™ laryngeal mask airways were selected more frequently (P < 0.0001), oropharyngeal leak pressure (P = 0.02) was higher, leak volume (P = 0.004) and leak fraction (P = 0.007) were lower, and oropharyngeal leaks (P = 0.03) were detected less frequently. Conclusion:Size selection for the ProSeal™ laryngeal mask airway is equally effective using the manufacturer’s weight-based formula or the sex-based formula in healthy, anesthetized, paralyzed adult patients, but leakage of small volumes of air from the mouth occurs less frequently with the sex-based formula.

A silicone-based wire-reinforced tracheal tube with a hemispherical bevel reduces nasal morbidity for nasotracheal intubation

We tested the hypothesis that a silicone-based wire-reinforced tracheal tube with a hemispherical bevel is superior to a polyvinyl chloride (PVC)-based precurved tube with a conventional diagonal bevel for nasotracheal intubation. Eighty anesthetized paralyzed adults (ASA physical status I–II) requiring nasotracheal intubation for tonsillectomy were randomly allocated into two equal-sized groups for airway management with the silicone tracheal tube or PVC tracheal tube. Intubation was subdivided into three phases: 1) passage through the nose into the pharynx, 2) laryngoscope-guided passage into the glottic inlet, and 3) laryngoscope-guided passage into the trachea. A specific sequence of airway maneuvers was followed at each stage if it was unsuccessful. The number of attempts and intubation time were documented by an unblinded observer. The frequency of epistaxis and postoperative nasal complications was documented by blinded observers. There were no intubation failures. The number of attempts at pharyngeal (47 versus 56; P = 0.04) and tracheal (43 versus 55; P = 0.005) placement was smaller for the silicone tracheal tube, but the number of attempts at glottic placement was more (72 versus 49; P < 0.0001). Intubation time was similar. The frequency (32% versus 80%; P < 0.0001) and severity of epistaxis were less for the silicone tracheal tube. The total number of postoperative nasal symptoms was smaller for the silicone tracheal tube (10 versus 21; P < 0.05). We conclude that the pharyngeal and tracheal placement phases of nasotracheal intubation require fewer attempts with the silicone tracheal tube than the PVC tracheal tube but that the glottic placement phase requires more attempts. Nasal morbidity is less common with the silicone tracheal tube.

Enhancement of pressor response to intravenous phenylephrine following oral clonidine medication in awake and anaesthetized patients.

Clonidine, an α2-adrenergic agonist, augments the pressor response to intravenous ephedrine. If this effect is partly due to clondine-induced potentiation of α1-adrenoceptor-mediated vasoconstriction, it is also assumed that clonidine would enhance the pressor effect of phenylephrine as an α1-adrenergic agonist. The authors studied haemodynamic responses to intravenous phenylephrine in 80 patients who received either preanaesthetic medication with clonidine approximately 5 μg · kg−1 po (clonidine group, n = 40), or no medication (control group, n =40). Each group was further divided into either awake subjects (n = 20) or subjects anaesthetized with enflurane and nitrous oxide in oxygen (n = 20). Haemodynamic measurements were made at one-minute intervals for ten minutes after phenylephrine 2 μg · kg−1 iv was injected as a bolus. The magnitudes of maximal mean blood pressure increases in the clonidine group (26 ± 7% (mean ± SD) for awake and 32 ± 15% for anaesthetized subjects) were greater (P < 0.05) than in the control group (13 ± 7% for awake and 18 ± 7% for anaesthetized subjects). However, there was no difference in the pressor effect of phenylephrine between awake and anaesthetized patients in both groups. Oral clonidine preanaesthetic medication, 5 μg · kg−1, augments the pressor responses to phenylephrine 2 μg · kg−1 iv in awake and anaesthetized patients. These results suggest that the enhancement of the pressor responses to phenylephrine following oral clonidine may be due to clonidine-induced potentiation of α1-adrenoceptor-mediated vasoconstriction. This implies that restoration of blood pressure can be achieved effectively by phenylephrine in hypotensive patients with clonidine premedication.RésuméLa clonidine, un agoniste α2-adrénergique exagère la réponse vasopressive à l’éphédrine iv. Si cet effet est en partie dû à la potentialisation de la vasoconstriction à médiation α1-adrénergique induite par la clonidine, on peut assumer que la clonidine exagérera aussi l’effet vasopressur de la phényléphrine, cet autre agoniste α1-adrénergique. Les auteurs ont étudié les réponses hémodynamiques provoquées par la phényléphrine iv chez 80 patients qui avaient été prémédiqués à la clonidine à la dose approximative de 5 μg · kg−1 po (groupe clonidine, n = 40) ou qui n’avaient pas reçu de clonidine (groupe contrôle, n = 40). Chaque groupe a été subdivisé en deux sous-groupes: sujets éveillés (n = 20) ou sujets anesthésiés à l’enflurane et au protoxyde d’azote en oxygène (n = 20). Les mesures hémodynamiques ont été effectuées à une min d’intervalle pendant dix minutes après l’injection d’un bolus de phényléphrine 2 μg · kg−1. L’ordre de grandeur de l’augmentation maximale de la pression moyenne pour le groupe clonidine (sujets éveillés 26 ± 7% (moyenne ± SD), sujets anesthésiés 32 ± 15%) est plus élevé (P < 0,05) que pour le groupe contrôle (sujets éveillés 13 ± 7%, sujets anesthésiés 18 ± 7%). Cependant, l’effet vasopresseur de la phényléphrine n’est pas différent entre patients éveillés ou anesthésiés de chaque groupe. En prémédication, la clonidine 5 μg · kg−1 po augmente l’effet vasopresseur de la phényléphrine 2 μg · kg−1 iv aussi bien chez les patients éveillés qu’anesthésiés. Ces résultats portent à croire que l’exagération des réponses pressives provoquées par la phényléphrine après la clonidine po pourraient être causées par la potentialisation de la vasoconstriction à médiation α1-adrénergique. On peut donc rétablir la pression artérielle efficacement avec la phényléphrine chez le patient hypotendu prémédiqué à la clonidine.

Routine use of the intubating laryngeal mask airway results in increased upper airway morbidity.

PurposeThe classic laryngeal mask airway (LMA) has a soft, silicone tube and the intubating laryngeal mask airway (ILM) has a rigid, silicone-coated steel tube. We compare postoperative pharyngolaryngeal morbidity in patients randomised to receive either device.MethodsSixty-five female patients (ASA physical status class I or II, aged 18–80 yr) undergoing balanced regional anesthesia for gynecological laparotomy expected to last one to two hours were randomly assigned for airway management with the LMA or ILM. Intracuff pressure was maintained at 60 cm H2O. Postoperative pharyngolaryngeal morbidity (sore throat, difficulty swallowing, sore mouth, sore neck/jaw, hoarseness) was assessed at two, 24 and 48 hr by blinded investigators.ResultsThe number of insertion attempts and duration of anesthesia was similar between groups. Sore throat was more common for the ILM at two hours (44 vs 15%, P=0.01), 24 hr (59 vs 21%, P=0.008) and 48 hr (34 vs 3%, P=0.005). Sore mouth was more common for the ILM at two hours (16 vs 0%, P=0.02) and 24 hr (12 vs 0%, P=0.04), but not at 48 hr (6 vs 3%). Difficulty swallowing was more common for the ILM at two hours (25 vs 0%, P=0.04), but not at 24 hr (31 vs 3%) and 48 hr (12 vs 9%). There were no differences in the incidence of sore jaw/neck (ILM, 3–12%; LMA, 0–3%) and hoarseness (ILM, 12–31%; LMA, 16–18%). There was no correlation between postoperative pharyngolaryngeal morbidity and duration of anesthesia. Conclusion: Pharyngolaryngeal morbidity is more common with the ILM than the LMA following anesthesia lasting one to two hours.RésuméObjectifLe masque laryngé traditionnel (ML) possède un tube de silicone mou tandis que le masque laryngé d’intubation (MLI) comporte un tube de métal rigide enrobé de silicone. Nous comparons la morbidité pharyngolaryngée postopératoire chez des patientes qui ont accepté de recevoir, au hasard, l’un ou l’autre masque.MéthodeSoixantecinq femmes (d’état physique ASA I ou II, de 18 à 80 ans) devant subir une anesthésie régionale balancée pendant une laparotomie gynécologique, censée durer une ou deux heures, ont été réparties au hasard pour une intubation avec le ML ou le MLI. La pression à l’intérieur du ballonnet a été maintenue à 60 cm H2O. La morbidité pharyngolaryngienne postopératoire (mal de gorge, difficulté d’avaler, irritation de la bouche, douleur au cou/à la mâchoire, enrouement) a été évaluée à deux, 24 et 48 h par des expérimentateurs impartiaux.RésultatsLe nombre d’essais nécessaires pour insérer le masque et la durée de l’anesthésie ont été similaires dans les deux groupes. Le mal de gorge a été plus fréquent avec le MLI à deux heures (44 vs 15 %, P = 0,01), à 24 h (59 vs 21 %, P = 0,008) et à 48 h (34 vs 3 %, P = 0,005). L’irritation de la bouche a été plus fréquente aussi avec le MLI à deux heures (I6 vs O%, P = 0,02) et à 24 h (12 vs 0 %, P = 0,04), mais non à 48 h (6 vs 3 %). La difficulté d’avaler se retrouve plus souvent avec le MLI à deux heures (25 vs 0 %, P = 0,04), mais non à 24 h (31 vs 3 %) ni à 48 h (12 vs 9 %). L’incidence de douleur au cou/à la mâchoire n’a pas présenté de différence intergroupe (MLI, 3-12 %; ML, 0-3 %), ni l’enrouement (MLI, 12-31 %; ML, 16-18 %). Il n’y a pas eu de corrélation entre la morbidité pharyngo-laryngienne postopératoire et la durée de l’anesthésie.ConclusionLa morbidité pharyngo-laryngienne est plus élevée avec le MLI qu’avec le ML à la suite d’une anesthésie qui dure une ou deux heures.