Tomoki Sasakawa

Pentax-AWS airway Scope as an alternative for awake flexible fiberoptic intubation of a morbidly obese patient in the semi-sitting position

For anesthesia induction in a morbidly obese patient with a full stomach, awake flexible fiberoptic bronchoscope (FOB) intubation in the semi-sitting position may be a suitable choice. A new rigid indirect videolaryngoscope, the Pentax-AWS system, has a unique feature of an adjustable built-in monitor and is designed to be used in patients in various positions. However, the efficacy of its use in such situations has not been investigated or reported. We used the Pentax-AWS system for the intubation of a morbidly obese patient (body mass index >50) who was at risk of regurgitation, anticipated difficult intubation, and supine hypotensive syndrome due to inferior vena cava compression by a huge ovarian cyst. The patient was placed in the sitting position during the intubation procedure. The patient’s trachea was intubated with the Pentax-AWS by an anesthesiologist positioned at the patient’s right and facing her. The Pentax-AWS offered easy intubation under good visualization of the glottic aperture as a consequence of its adjustable integrated monitor, in contrast to difficult intubation with other videolaryngoscopes which require an external monitor. This report illustrates that the Pentax-AWS is useful as an alternative for flexible fiberoptic intubation under these circumstances, as a consequence of its adjustable built-in monitor and integrated tube channel.

Immobilization with Atrophy Induces De Novo Expression of Neuronal Nicotinic α7 Acetylcholine Receptors in Muscle Contributing to Neurotransmission

Background:Mature acetylcholine receptor (AChR) isoform normally mediates muscle contraction. The hypothesis that &agr;7AChRs up-regulate during immobilization and contribute to neurotransmission was tested pharmacologically using specific blockers to mature (waglerin-1), immature (&agr;A-OIVA), and &agr;7AChRs (methyllycaconitine), and nonspecific muscle AChR antagonist, &agr;-bungarotoxin. Methods:Mice were immobilized; contralateral limbs were controls. Fourteen days later, anesthetized mice were mechanically ventilated. Nerve-stimulated tibialis muscle contractions on both sides were recorded, and blockers enumerated above sequentially administered via jugular vein. Data are mean ± standard error. Results:Immobilization (N = 7) induced tibialis muscle atrophy (40.6 ± 2.8 vs. 52.1 ± 2.0 mg; P < 0.01) and decrease of twitch tension (34.8 ± 1.1 vs. 42.9 ± 1.5 g; P < 0.01). Waglerin-1 (0.3 ± 0.05 &mgr;g/g) significantly (P = 0.001; N = 9) depressed twitch tension on contralateral (≥97%) versus immobilized side (approximately 45%). Additional waglerin-1 (total dose 1.06 ± 0.12 &mgr;g/g or approximately 15.0 × ED50 in normals) could not depress twitch of 80% or greater on immobilized side. Immature AChR blocker, &agr;A-OIVA (17.0 ± 0.25 &mgr;g/g) did not change tension bilaterally. Administration of &agr;-bungarotoxin (N = 4) or methyllycaconitine (N = 3) caused 96% or greater suppression of the remaining twitch tension on immobilized side. Methyllycaconitine, administered first (N = 3), caused equipotent inhibition by waglerin-1 on both sides. Protein expression of &agr;7AChRs was significantly (N = 3; P < 0.01) increased on the immobilized side. Conclusions:Ineffectiveness of waglerin-1 suggests that the twitch tension during immobilization is maintained by receptors other than mature AChRs. Because &agr;A-OIVA caused no neuromuscular changes, it can be concluded that immature AChRs contribute minimally to neurotransmission. During immobilization approximately 20% of twitch tension is maintained by up-regulation of &agr;-bungarotoxin- and methyllycaconitine-sensitive &agr;7AChRs.

Nonsurgically induced disuse muscle atrophy and neuromuscular dysfunction upregulates alpha7 acetylcholine receptors

Previous models of muscle disuse have invariably used surgical methods that require the repetitive application of plaster casts. A method of disuse atrophy that does not require such repetitive applications is described herein. Modified plastic pipette tubing was applied to a single hindlimb (mouse), from thigh to foot, resulting in immobilization of the knee in the extension position, and the ankle in the plantar flexion position. This method resulted in the loss of soleus muscle to 11%, 22%, 39%, and 45% of its original mass at 3, 7, 14, and 21 days, respectively, in association with a significant decrease of tibialis twitch (25%) and tetanic tensions (26%) at 21 days, compared with the contralateral side and (or) sham-immobilized controls. Immunohistochemical analysis of the soleus using fluorescent α-bungarotoxin revealed a significant increase in the number of synapses per unit area (818 + 31 compared with 433 + 16/mm(2)) and an increase in muscle fibers per unit area (117 compared with 83/mm(2)), most likely related to the atrophy of muscle fibers bringing synapses closer. A 3-fold increase in alpha7 acetylcholine receptor (α7AChR) protein expression, along with increased expression of α1AChR subunit in the immobilized side compared with the contralateral side was observed. The physiology and pharmacology of the novel finding of upregulation of α7AChRs with disuse requires further study.

Displacement of the epiglottis during intubation with the Pentax-AWS Airway Scope.

The Pentax-AWS system is a rigid indirect video laryngoscope with integrated tube guidance. Complications associated with this device are not well understood. We report two cases of epiglottis malposition during intubation with the Pentax-AWS. The standard technique of using the Pentax-AWS system involves direct elevation of the epiglottis for exposure of the vocal cords. The blade tip should be passed posterior to the epiglottis for laryngeal exposure, but pressure on the anterior surface of the epiglottis by the tip can rarely happen even during the correct maneuver. Although the Pentax-AWS provides clear images of the airway structures, it is sometimes difficult to observe the epiglottis continuously because the camera is located beneath the blade tip. Consequently, the view of the epiglottis from the camera may be impeded by the blade tip and may result in undiagnosed epiglottis malposition. The AWS’s structural feature and its approach to the larynx can be associated with increased chance of unexpected epiglottis folding. It is particularly important to confirm normal position of the epiglottis during withdrawal of the device to prevent this complication.

Transvalvular leakage after the implantation of stented bovine pericardial valves is not only central

To the editor: It is well known that mild central transvalvular leakage is usually seen after the implantation of a stented bovine pericardial valve [1,2]. However, noncentral regurgitation has not been reported, and the permissible regurgitation volume and the outcome in the case reported here were not clear. We observed noncentral leakage after the implantation of a stented bovine pericardial valve in a patient who was followed up until 2 weeks after surgery. The patient was a man in his seventies who had suffered from aortic insuffi ciency. He underwent aortic valve replacement using a CarpentierEdwards PERIMOUNT Aortic Heart Valve (Edwards Lifesciences, Irvine, CA, USA). The transvalvular leakage was not central but diagonal, and a regurgitation jet was seen toward the anterior leafl et of the mitral valve (Fig. 1). LIVE xPlane using iE33 (Philips Medical Systems, Bothell, WA, USA) revealed that the regurgitation had originated in three coaptation zones. LIVE xPlane provides two-dimensional Fig. 1. Stented bovine pericardial valve, aortic position. Color Doppler fl ow transesophageal echocardiography midesophageal aortic valve long-axis view at a multiplane angle of 132° shows regurgitant jets. The regurgitant jets did not advance at the center of the left ventricular outfl ow tract (LVOT), but were oblique in the LVOT and were seen toward to the anterior leafl et of the mitral valve

The Pentax-AWS is particularly suitable for facilitating intubation in edentulous geriatric patients

tion, the percentage of glottic opening (POGO) score [1], the intubation diffi culty scale (IDS) [2], and the number of intubation attempts were recorded. The time for intubation was defi ned as the time taken from the blade fi rst passing the incisors until passage of the tracheal tube was completed. Data were analyzed using the unpaired t-test and the χ 2 test, and P < 0.05 was considered signifi cant. Patient profi les were not different between the groups, except for the inter-incisor distance (IID). There was a signifi cant difference between the groups in the anatomical structure observed after the initial blade rotation maneuver; the vocal cords were more frequently observed in the FD group. The total time for intubation was signifi cantly less in the FD group than the NT group. The POGO score, IDS, and number of intubation attempts did not differ between the groups (Table 1). Our result showed that intubation with the AWS was facilitated when the patients were edentulous. It seems that the increased IID in the edentulous patients may have been responsible for this result. As a consequence of the lack of teeth, the working space necessary for AWS manipulation was increased. This may have facilitated the insertion of the blade tip behind the epiglottis after blade rotation, resulting in faster laryngeal exposure and subsequent faster intubation.

Pregnancy suppresses neuropathic pain induced by chronic constriction injury in rats through the inhibition of TNF-α

Purpose Pregnancy-induced analgesia develops during late pregnancy, but it is unclear whether this analgesia is effective against neuropathic pain. The detailed molecular mechanisms underlying pregnancy-induced analgesia have not been investigated. We examined the antinociceptive effect of pregnancy-induced analgesia in a neuropathic pain model and the expression of tumor necrosis factor (TNF)-α, glial fibrillary acidic protein (GFAP), Iba-1, and c-Fos in the spinal dorsal horn just before parturition. Materials and methods Female Sprague Dawley rats (200–250 g) were randomly assigned to one of four groups (pregnant + chronic constriction injury [CCI]; pregnant + sham injury; not pregnant + CCI; and not pregnant + sham injury). Separate groups were used for the behavioral and tissue analyses. CCI of the left sciatic nerve was surgically induced 3 days after confirming pregnancy in the pregnancy group or on day 3 in the not pregnant group. The spinal cord was extracted 18 days after CCI. TNF-α, GFAP, Iba-1, and c-Fos expression levels in the spinal dorsal horn were measured by Western blot analysis. Mechanical threshold was tested using von Frey filaments. Results The lowered mechanical threshold induced by CCI was significantly attenuated within 1 day before parturition and decreased after delivery. TNF-α expression in CCI rats was decreased within 1 day before parturition. Further, GFAP, Iba-1, and c-Fos expression in the spinal dorsal horn was reduced in the pregnant rats. Serum TNF-α in all groups was below measurable limits. Conclusion Our findings indicate that pregnancy-induced analgesia suppresses neuropathic pain through reducing spinal levels of TNF-α, GFAP, Iba-1, and c-Fos in a rat model of CCI.

Block of postjunctional muscle-type acetylcholine receptors in vivo causes train-of-four fade in mice

BACKGROUND Train-of-four (TOF) fade during nerve-mediated muscle contraction is postulated to be attributable to inhibition of prejunctional nicotinic α3β2 acetylcholine receptors (nAChRs), while decrease of twitch tension is attributable to block of postjunctional muscle nAChRs. The validity of these presumptions was tested using specific prejunctional and postjunctional nAChR antagonists, testing the hypothesis that fade is not always a prejunctional phenomenon. METHODS Pentobarbital anaesthetized mice had TOF fade measured after administration of: either 0.9% saline; the prejunctional α3β2 nAChR antagonist, dihydro-β-erythroidine (DHβE); the postjunctional nAChR antagonists, α-bungarotoxin (α-BTX) or α-conotoxin GI; and a combination of α-BTX and DHβE; or a combination of α-conotoxin GI and DHβE. RESULTS Saline caused no neuromuscular changes. Administration of muscle nAChR antagonists, α-BTX or α-conotoxin GI caused significant decrease of twitch tension and TOF fade compared with baseline (P<0.01). DHβE alone caused no change of twitch tension or fade even after 90 min, but its coadministration with α-BTX or α-conotoxin GI significantly accelerated the onset of paralysis and degree of fade compared with α-BTX or α-conotoxin GI alone (P<0.01). CONCLUSIONS Occupation of postjunctional nAChRs alone by α-BTX or α-conotoxin GI causes fade. As the prejunctional effects of DHβE on fade became manifest only when co-administered with α-BTX or α-conotoxin GI, specific inhibition of prejunctional nAChR alone is not necessary and sufficient to cause fade. Fade observed during repetitive nerve stimulation can be because of block of either postjunctional nAChRs alone, or block of prejunctional and postjunctional nAChRs together.

Unilateral Hypoglossal Nerve Palsy after Use of the Laryngeal Mask Airway Supreme

Purpose. Hypoglossal nerve palsy after use of the laryngeal mask airway (LMA) is an exceptionally rare complication. We present the first case of unilateral hypoglossal nerve palsy after use of the LMA Supreme. Clinical Features. A healthy 67-year-old female was scheduled for a hallux valgus correction under general anesthesia combined with femoral and sciatic nerve blocks. A size 4 LMA Supreme was inserted successfully at the first attempt and the cuff was inflated with air at an intracuff pressure of 60 cmH2O using cuff pressure gauge. Anesthesia was maintained with oxygen, nitrous oxide (67%), and sevoflurane under spontaneous breathing. The surgery was uneventful and the duration of anesthesia was two hours. The LMA was removed as the patient woke and there were no immediate postoperative complications. The next morning, the patient complained of dysarthria and dysphasia. These symptoms were considered to be caused by the LMA compressing the nerve against the hyoid bone. Conservative treatment was chosen and the paralysis recovered completely after 5 months. Conclusion. Hypoglossal nerve injury may occur despite correct positioning of the LMA under the appropriate intracuff pressure. A follow-up period of at least 6 months should be taken into account for the recovery.

Prediction of Optimal Reversal Dose of Sugammadex after Rocuronium Administration in Adult Surgical Patients

The objective of this study was to determine the point after sugammadex administration at which sufficient or insufficient dose could be determined, using first twitch height of train-of-four (T1 height) or train-of-four ratio (TOFR) as indicators. Groups A and B received 1 mg/kg and 0.5 mg/kg of sugammadex, respectively, as a first dose when the second twitch reappeared in train-of-four stimulation, and Groups C and D received 1 mg/kg and 0.5 mg/kg of sugammadex, respectively, as the first dose at posttetanic counts 1–3. Five minutes after the first dose, an additional 1 mg/kg of sugammadex was administered and changes in T1 height and TOFR were observed. Patients were divided into a recovered group and a partly recovered group, based on percentage changes in T1 height after additional dosing. T1 height and TOFR during the 5 min after first dose were then compared. In the recovered group, TOFR exceeded 90% in all patients at 3 min after sugammadex administration. In the partly recovered group, none of the patients had a TOFR above 90% at 3 min after sugammadex administration. An additional dose of sugammadex can be considered unnecessary if the train-of-four ratio is ≥90% at 3 min after sugammadex administration. This trial is registered with UMIN000007245.