Noriko Taguchi

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.

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.

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.

Fluoxetine has neuroprotective effects after cardiac arrest and cardiopulmonary resuscitation in mouse.

AIMS Fluoxetine, a selective serotonin reuptake inhibitor, is protective in a rat focal ischaemia model via anti-inflammatory mechanisms. Cardiac arrest and cardiopulmonary resuscitation (CA/CPR) were performed in mice to test the hypothesis that fluoxetine protects the brain following global cerebral ischaemia, even when administered after an insult. METHODS Global cerebral ischaemia was induced with 8 min CA/CPR in C57BL/6 male mice. Thirty minutes after recovery of spontaneous circulation, the mice were randomly assigned into 3 groups and administered fluoxetine; fluoxetine (5 mg/kg: n=15, 10 mg/kg: n=15) or vehicle (NaCl: n=15). Three days after CA/CPR, sensorimotor evaluations were conducted and brains were removed for histological evaluation of the hippocampus and caudate putamen. RESULTS Analysis of histological damage 72 h after resuscitation revealed that low dose fluoxetine (5 mg/kg) did not protect, while high dose (10 mg/kg) fluoxetine protected neurons in the caudate putamen. In contrast, there were no protective effects in the hippocampus at either dose. In agreement with histological observations of neuronal damage in the caudate putamen, high dose fluoxetine decreased sensorimotor deficits following CA/CPR compared to vehicle-treated animals. CONCLUSIONS Our data showed that 10mg/kg fluoxetine administered following global cerebral ischaemia decreases neuronal damage. Although long-term neuroprotection needs further study, the results of our study suggest that fluoxetine may have therapeutic potential when administered after global cerebral ischaemia, cardiac arrest and cardiopulmonary resuscitation.

Determination of the distance between the laryngoscope blade and the upper incisors during direct laryngoscopy : comparisons of a curved, an angulated straight, and two straight blades

We compared visibility and dental complications from a variety of blades during tracheal intubation. Ninety-eight patients who received tracheal intubation were enrolled. They were divided into two groups: Study 1 (n = 50) and Study 2 (n = 48). Four laryngoscopic evaluations were planned for each patient using Miller and Wisconsin straight blades with different heel heights, a Macintosh curved blade, and a Belscope angulated straight blade (Study 1: Miller No. 3, Wisconsin No. 3, Macintosh No. 4, and Belscope medium; and Study 2 Miller No. 2, Wisconsin No. 2, Macintosh No. 3, and Belscope medium, respectively). All laryngoscopies were performed by the same anesthesiologist. The distance between the blade and the upper central incisors was measured when the optimum visibility of the glottis was obtained. The visibility was determined according to the Cormack and Lehane grading. Analysis of the distance between the blade and upper incisors was performed using the results of the 44 patients (166 distances) in Study 1 and the 48 patients (181 distances) in Study 2 who had a visibility of two or better. The Belscope blade provided a significantly greater visual field than the other types of blade. Two patients sustained a fracture of the central incisor and subluxation of the central incisor, respectively, during laryngoscopy in which a Wisconsin blade was used. The average incidence of dental injury was 1/191. The Belscope blade may contribute to a reduced likelihood of upper dental injuries during laryngoscopy.

Arteriovenous differences in PCO2 and cardiac output during CPR in the dog

Using 14 mongrel dogs, we investigated the correlation between arteriovenous differences of PCO2 (AVD-CO2) and cardiac output (CO) during CPR. Ventricular fibrillation was induced by an electrical current and the respirator was stopped for 5 min. Cardiopulmonary resuscitation (CPR) was performed during the next 10 min and CO was measured with simultaneous arterial and venous blood gas analysis. CO was measured 26 times during CPR. The animals were divided into two groups according to the values of CO during CPR: low-CO group (CO < 0.3 l/min) and high-CO group (CO > or = 0.3 l/min). AVD-CO2 in the low CO group was 39.8 +/- 5.7 mmHg and that of the high group was 27.4 +/- 14.8 mmHg (mean +/- S.D., P < 0.05). In conclusion, AVD-CO2 showed an inverse result with the degree of CO during CPR.

Single administration of soluble epoxide hydrolase inhibitor suppresses neuroinflammation and improves neuronal damage after cardiac arrest in mice

Cardiac arrest (CA) causes ischemia-reperfusion injury in the whole body among victims. Especially in the brain, inflammation and neuronal cell death can lead to irreversible dysfunction. Our goal was to determine whether a single administration of soluble epoxide hydrolase inhibitor (AS2586144-CL) has a neuroprotective effect and decreases the inflammatory response after CA and cardiopulmonary resuscitation (CPR). Global cerebral ischemia was induced in male C57BL/6 mice with 8min of CA. Thirty minutes after recovery of spontaneous circulation, the mice were randomly assigned to three groups and administered AS2586144-CL: 1mg/kg (n=25), 10mg/kg (n=25), or 0mg/kg (vehicle, n=25). At 6 and 7 days after CA/CPR, behavioral tests were conducted and brains were removed for histological evaluation. Analysis of histological damage 7 days after CA/CPR revealed that 10mg/kg of AS2586144-CL protected neurons, and suppressed cytokine production and microglial migration into the hippocampus. Two hours after CA/CPR, 10mg/kg of AS2586144-CL suppressed serum tumor necrosis factor-α and hippocampal nuclear factor κB expression. Our data show that 10mg/kg of AS2586144-CL administered following CA/CPR suppresses inflammation and decreases neuronal damage.

Glibenclamide and Therapeutic Hypothermia Have Comparable Effect on Attenuating Global Cerebral Edema Following Experimental Cardiac Arrest

BackgroundCerebral edema is one of the major causes of mortality following cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). A subunit of the sulfonylurea receptor 1–transient receptor potential M4 (Sur1–TRPM4) channel has been implicated in the pathogenesis of ischemia-evoked cerebral edema. In this study, we examined whether glibenclamide (GBC), a Sur1–TRPM4 channel inhibitor, attenuates cerebral edema following CA/CPR and further examined the efficacy of GBC combined with therapeutic hypothermia.MethodsIsoflurane-anesthetized adult male wild-type C57Bl/6 mice subjected to 7-min CA/CPR were randomized into five groups: sham operation, control with normothermia, GBC with normothermia, control with hypothermia, and GBC with hypothermia. The primary outcome was to evaluate regional brain water content; the secondary outcome was to measure blood glucose level, Sur1–TRPM4 expression, and pro-inflammatory factor expression.ResultsCompared with normothermia, GBC treatment or hypothermia significantly attenuated brain water content in mice subjected to CA/CPR. GBC combined with hypothermia had no additional effects on attenuating cerebral edema. Pro-inflammatory factor messenger RNA expression (TNF-α and IL-6), NFκβ activation, and SUR1–TRPM4 levels were upregulated after CA/CPR. Compared with normothermia, hypothermia, but not GBC, partly suppressed these factors’ expression.ConclusionsGBC attenuated cerebral edema following CA/CPR by blocking Sur1–TRPM4 channels upregulated by CA insult. The effect of GBC was comparable with that of therapeutic hypothermia alone. These results suggest that GBC is an alternative approach for treating CA-evoked cerebral edema.

The effect of age on retrieval of local anesthetic solution from the epidural space.

We conducted this prospective study to determine whether advancing age is correlated with retrieval of local anesthetic solution from the epidural space.Three hundred forty-six patients (ASA physical status I or II, 20-93 yr of age, 177 female and 169 male patients) undergoing epidural anesthesia were enrolled. The epidural space was identified by a loss of resistance technique using air, and a catheter was introduced 3 cm. Three milliliters of 2% lidocaine with epinephrine was injected as a study dose by hand at a rate of 1 mL/s with the patient in the supine position. The syringe was immediately aspirated to retrieve the local anesthetic solution. A retrieved volume of 0.5 mL or more with a glucose concentration less than 6 mg/dL was defined as retrieval positive, and a volume of less than 0.5 mL was defined as retrieval negative. There was a significant correlation between age and retrieval volume among all the patients (Y = 0.008X-0.222, P < 0.0001) with a significant increase in the positive retrieval incidence and volume from the patients in their 50s (11%, 0.6 +/- 0.3 mL) to the patients in their 60s (26%, 1.0 +/- 0.6 mL) (P < 0.05 for both). The incidence of positive retrieval and the retrieval volume were greater in the patients in their 60s and older (30%, 1.1 +/- 0.63 mL) than in the younger than 60 (10%, 0.6 +/- 0.3 mL) (P < 0.0001 and P < 0.001). The glucose concentration was 2.3 +/- 1.2 mg/dL in the positive cases. We conclude that there is a weak positive correlation between age and the local anesthetic solution retrieved from the epidural space. Implications: We conducted a study in 346 patients to determine whether advancing age could be correlated with retrieval of local anesthetic solution from the epidural space. We found a weak positive correlation between advanced age and the amount of solution retrievable from the epidural space. Further studies are required to determine whether this phenomenon may call for dose adjustments in patients aged more than 60 yr. (Anesth Analg 1997;85:1091-6)