Remifentanil does not increase urine output during oral surgery, contrary to its effect during other surgeries - a cohort study / Remifentanil não aumenta a diurese durante cirurgia oral, contrariamente ao seu efeito durante outras cirurgias - estudo de coorte

Abstract Background: An increase in urine output by remifentanil injection during laparoscopic procedures and surgeries such as cardiac and gynecological procedures, due to suppression of the stress response to surgery, has been reported. The aim of our prospective, observational, cohort study was to assess the effect of remifentanil analgesia on urine output during dental and minor oral surgery by comparing intraoperative urine output under defined infusion volumes with and without the use of remifentanil. Methods: Dental patients aged 16 years or older, American Society of Anesthesiologists physical status 1, with no renal diseases or abnormal blood values of serum creatinine and BUN, not on treatment with diuretic drugs, and undergoing minor oro-maxillofacial surgery or dental treatment under inhalation general anesthesia were included in this study. Urethral catheterization was performed after anesthesia induction, and urine output was measured every 30 minutes. We measured urine volume (mL) and rate of urine output (mL.kg-1.h-1) intraoperatively, and compared these parameters between patients who did and did not receive remifentanil during the intraoperative period. Results: Eighty-seven patients were categorized into the remifentanil group (n = 43) or remifentanil non-use group (n = 44). Both volume of urine (mL) and rate of urine output (mL.kg-1.h-1) were not significantly different between the two groups (remifentanil group, 372.3 ± 273.5 mL, 1.8 ± 1.1 mL.kg-1.h-1; remifentanil non-use group, 343.3 ± 283.3 mL, 1.9 ± 1.2 mL.kg-1.h-1; p = 0.63; 0.57). Conclusion: Our results show that use of remifentanil during dental and minor oral surgeries does not increase urine output.

Resumo Justificativa: Foi relatado um aumento na diurese após a injeção de remifentanil durante procedimentos laparoscópicos e cirurgias cardíacas e ginecológicas, devido à supressão da resposta ao estresse da cirurgia. O objetivo de nosso estudo prospectivo, observacional e de coorte foi avaliar o efeito da analgesia com remifentanil sobre a diurese durante cirurgia odontológica e oral de pequeno porte e comparar a diurese no intraoperatório sob infusão de volumes definidos, com e sem o uso de remifentanil. Métodos: Pacientes odontológicos ≥ 16 anos, estado físico ASA I, sem doenças renais ou valores sanguíneos anormais de creatinina sérica e ureia, sem tratamento com diuréticos e submetidos à cirurgia bucomaxilofacial de pequeno porte ou tratamento odontológico sob anestesia geral inalatória foram incluídos neste estudo. Cateterismo uretral foi feito após a indução da anestesia e a diurese foi medida a cada 30 min. Medimos o volume de urina (mL) e a taxa de diurese (mL.kg-1.h-1) no intraoperatório e comparamos esses parâmetros entre os pacientes que receberam e que não receberam remifentanil durante o período intraoperatório. Resultados: Foram designados 87 pacientes para os grupos com remifentanil (n = 43) ou grupo sem remifentanil (n = 44). O volume de urina (mL) e a taxa de diurese (mL.kg-1.h-1) não foram significativamente diferentes entre os dois grupos (grupo com remifentanil: 372,3 ± 273,5 mL, 1,8 ± 1,1 mL.kg-1.h-1; grupo sem remifentanil: 343,3 ± 283,3 mL, 1,9 ± 1,2 mL.kg-1.h-1; p = 0,63; 0,57). Conclusão: Nossos resultados mostram que o uso de remifentanil durante as cirurgias odontológicas e de pequeno porte não aumenta a diurese.

[Remifentanil does not increase urine output during oral surgery, contrary to its effect during other surgeries - a cohort study]. / Remifentanil não aumenta a diurese durante cirurgia oral, contrariamente ao seu efeito durante outras cirurgias ­ estudo de coorte.

BACKGROUND: An increase in urine output by remifentanil injection during laparoscopic procedures and surgeries such as cardiac and gynecological procedures, due to suppression of the stress response to surgery, has been reported. The aim of our prospective, observational, cohort study was to assess the effect of remifentanil analgesia on urine output during dental and minor oral surgery by comparing intraoperative urine output under defined infusion volumes with and without the use of remifentanil. METHODS: Dental patients aged 16 years or older, American Society of Anesthesiologists physical status 1, with no renal diseases or abnormal blood values of serum creatinine and BUN, not on treatment with diuretic drugs, and undergoing minor oro-maxillofacial surgery or dental treatment under inhalation general anesthesia were included in this study. Urethral catheterization was performed after anesthesia induction, and urine output was measured every 30minutes. We measured urine volume (mL) and rate of urine output (mL.kg-1.h-1) intraoperatively, and compared these parameters between patients who did and did not receive remifentanil during the intraoperative period. RESULTS: Eighty-seven patients were categorized into the remifentanil group (n=43) or remifentanil non-use group (n=44). Both volume of urine (mL) and rate of urine output (mL.kg-1.h-1) were not significantly different between the two groups (remifentanil group, 372.3±273.5mL, 1.8±1.1mL.kg-1.h-1; remifentanil non-use group, 343.3±283.3mL, 1.9±1.2mL.kg-1.h-1; p=0.63; 0.57). CONCLUSION: Our results show that use of remifentanil during dental and minor oral surgeries does not increase urine output.

Acoustic method respiratory rate monitoring is useful in patients under intravenous anesthesia.

Respiratory depression can occur during intravenous general anesthesia without tracheal intubation. A new acoustic method for respiratory rate monitoring, RRa® (Masimo Corp., Tokyo, Japan), has been reported to show good reliability in post-anesthesia care and emergency units. The purpose of this study was to investigate the reliability of the acoustic method for measurement of respiratory rate during intravenous general anesthesia, as compared with capnography. Patients with dental anxiety undergoing dental treatment under intravenous anesthesia without tracheal intubation were enrolled in this study. Respiratory rate was recorded every 30 s using the acoustic method and capnography, and detectability of respiratory rate was investigated for both methods. This study used a cohort study design. In 1953 recorded respiratory rate data points, the number of detected points by the acoustic method (1884, 96.5 %) was significantly higher than that by capnography (1682, 86.1 %) (P < 0.0001). In the intraoperative period, there was a significant difference in the LOA (95 % limits of agreement of correlation between difference and average of the two methods)/ULLOA (under the lower limit of agreement) in terms of use or non-use of a dental air turbine (P < 0.0001). In comparison between capnography, the acoustic method is useful for continuous monitoring of respiratory rate in spontaneously breathing subjects undergoing dental procedures under intravenous general anesthesia. However, the acoustic method might not accurately detect in cases in with dental air turbine.

Hypotonic fluid reduce serum sodium compared to isotonic fluids during anesthesia induction in pediatric patients undergoing maxillofacial surgery-type of infusion affects blood electrolytes and glucose: an observational study.

BACKGROUND: Reportedly, administration of hypotonic fluids containing 30.8-74 mEq/L sodium with 5 % glucose may lead to serious hyponatremia or hyperglycemia. In Japan, hypotonic fluids containing 90 mEq/L sodium with 2.6 % glucose are commonly used. We compared blood electrolyte balance and blood glucose concentration with the use of isotonic (140 mEq/L sodium with 1 % glucose) versus hypotonic fluids in pediatric patients. METHODS: We studied 77 children aged 5 months to 2 years who underwent oro-maxillofacial surgery and dental treatment under general anesthesia. Patients were categorized according to the fluids infused (hypotonic or isotonic). Blood samples were obtained from the dorsalis pedis artery between the conclusion of anesthesia induction and commencement of surgery. We compared blood sodium, potassium and glucose concentrations in the two fluid groups during the pre-anesthesia and post-anesthesia-induction periods. RESULTS: There were no significant differences in pre-anesthesia values between isotonic (n = 35) and hypotonic groups (n = 42). There were significant differences between isotonic and hypotonic groups in post-anesthesia-induction concentrations of sodium (isotonic, 138.7 ± 1.4 mEq/L; hypotonic, 137.5 ± 1.3 mEq/L; p = 0.0003) and glucose (isotonic, 88.0 ± 9.4 mg/dL; hypotonic, 109.9 ± 18.4 mg/dL; p < 0.0001), while potassium concentrations were not significantly different (isotonic, 4.0 ± 0.3 mEq/L; hypotonic, 4.0 ± 0.2 mEq/L; p = 0.6615) between the two groups. CONCLUSION: Isotonic solution administration enables avoidance of serum sodium reduction and serum glucose elevation in infants, and may therefore enhance patient safety in comparison with hypotonic solutions. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry ( UMIN000014648 ), registration 25 July 2014.

Dexmedetomidine Dose Dependently Enhances the Local Anesthetic Action of Lidocaine in Inferior Alveolar Nerve Block: A Randomized Double-Blind Study.

BACKGROUND AND OBJECTIVES: Dexmedetomidine (DEX) dose dependently enhances the local anesthetic action of lidocaine in rats. We hypothesized that the effect might also be dose dependent in humans. We evaluated the effect of various concentrations of DEX with a local anesthetic in humans. METHODS: Eighteen healthy volunteers were randomly assigned by a computer to receive 1.8 mL of 1 of 4 drug combinations: (1) 1% lidocaine with 2.5 ppm (parts per million) (4.5 µg) DEX, (2) lidocaine with 5.0 ppm (9.0 µg) DEX, (3) lidocaine with 7.5 ppm (13.5µg) DEX, or (4) lidocaine with 1:80,000 (22.5 µg) adrenaline (AD), to produce inferior alveolar nerve block. Pulp latency and lower lip numbness (for assessing onset and duration of anesthesia) were tested, and sedation level, blood pressure, and heart rate were recorded every 5 minutes for 20 minutes, and every 10 minutes from 20 to 60 minutes. RESULTS: Pulp latency of each tooth increased compared with baseline, from 5 to 15 minutes until 60 minutes. There were no significant intergroup differences at any time point. Anesthesia onset was not different between groups. Anesthesia duration was different between groups (that with DEX 7.5 ppm was significantly longer than that with DEX 2.5 ppm and AD; there was no difference between DEX 2.5 ppm and AD). Blood pressure decreased from baseline in the 5.0 and 7.5 ppm DEX groups at 30 to 60 minutes, although there was no hypotension; moreover, heart rate did not change in any group. Sedation score did not indicate deep sedation in any of the groups. CONCLUSIONS: Dexmedetomidine dose dependently enhances the local anesthetic action of lidocaine in humans. Dexmedetomidine at 2.5 ppm produces similar enhancement of local anesthesia effect as addition of 1:80,000 AD.

Cuff depth and continuous chest auscultation method for determination of tracheal tube insertion depth in nasal intubation: observational study.

BACKGROUND: Incorrect endobronchial placement of the tracheal tube can lead to serious complications. Hence, it is necessary to determine the accuracy of tracheal tube positioning. Markers are included on tracheal tubes, in the process of their manufacture, as indicators of approximate intubation depth. In addition, continuous chest auscultation has been used for determining the proper position of the tube. We examined insertion depth using the cuff depth and continuous chest auscultation method (CC method), compared with insertion depth determined by the marker method, to assess the accuracy of these methods. METHODS: After induction of anesthesia, tracheal intubation was performed in each patient. In the CC method, the depth of tube insertion was measured when the cuff had passed through the glottis, and again when breath sounds changed in quality; the depth of tube insertion was determined from these values. In the marker method, the depth of tube insertion was measured and determined when the marker of the tube had reached the glottis, using insertion depth according to the marker as an index. RESULTS: Insertion depth by the marker method was 26.6 ± 1.2 cm and by the CC method was 28.0 ± 1.2 cm (P < 0.0001). The CC method indicated a significantly greater depth than the marker method. CONCLUSION: This study determined the safe range of tracheal tube placement. Tube positions determined by the CC method were about 1 cm deeper than those determined by the marker. This information is important to prevent accidental one-lung ventilation and accidental extubation. CLINICAL TRIAL REGISTRATION: UMIN No. UMIN000011375.

Associations between blood pressure responses to acute stress and impaired renal function and serum uric acid level.

The study aimed to examine correlations between blood pressure (BP) responses to direct laryngoscopy and tracheal intubation and parameters of renal function, serum uric acid (SUA) level, and mean preoperative BP. Fifty-four patients (≥ 40 years) who were scheduled for oral surgery were analyzed. General anesthesia was induced by the rapid sequence method without opioid analgesics. Systolic and diastolic BP (SBP, DBP) in the operation room were measured when an electrocardiogram, a BP cuff, and a pulse oximetry probe were attached to the patients (T1) and immediately after the trachea was intubated (T2). The ΔSBP was defined as the difference between SBP at T2 and T1. The increasing rate of SBP (ΔSBPr) was defined as ΔSBP/SBP at T1. SBP at T2 was associated with increasing age (R = 0.44), serum creatinine (R = 0.32), SUA (R = 0.30), mean preoperative SBP and DBP (R = 0.54 and 0.37, respectively), and reduced estimated glomerular filtration rate (eGFR) (R = -0.44). Serum creatinine and SUA were positively associated, and eGFR was negatively associated with ΔSBP (R = 0.36, 0.34, and -0.29) and ΔSBPr (R = 0.39, 0.37, and -0.29). Multivariate regression analysis revealed that age and mean preoperative SBP was independently associated with SBP at T2, and serum creatinine was independently associated with ΔSBP and ΔSBPr. These findings suggested that elevated serum creatinine level, as well as elevated preoperative BP level, was associated with enhanced BP responses to acute stress in middle-aged to elderly patients.

Required propofol dose for anesthesia and time to emerge are affected by the use of antiepileptics: prospective cohort study.

BACKGROUND: We investigated the impact of the type of neurological disorder on the required propofol dose for anesthesia and the time to emerge from anesthesia during dental treatment in patients with autism (AU), cerebral palsy (CP), and intellectual disability (ID), some of whom also had epilepsy. METHODS: We studied 224 patients with a neurological disorder who underwent dental treatment under intravenous general anesthesia. Patients were categorized according to neurological disorder (AU, CP, and ID; and with or without an antiepileptic). The propofol dose required for anesthesia, time to emerge, and modeled propofol blood concentration at emergence were evaluated. RESULTS: In patients not given an antiepileptic, we found no significant differences in the propofol dose, modeled propofol blood concentration at emergence, or time to emerge among patients with AU, CP, and ID (P > 0.05). When using an antiepileptic, the dose of propofol (5.7 ± 1.51 mg/kg/h) was significantly lower than without an antiepileptic (6.8 ± 1.27 mg/kg/h) (P < 0.0001). The modeled propofol blood concentration at emergence in patients given an antiepileptic (0.5 ± 0.03 µg/ml) was significantly lower than without an antiepileptic (0.7 ± 0.02 µg/ml) (P < 0.0001). The time to emerge in patients given an antiepileptic (29.5 ± 12.5 min) was significantly longer than without an antiepileptic (21.6 min ± 10.0 min) (P < 0.0001). CONCLUSION: The propofol dose required for anesthesia and the time to emerge from anesthesia are not affected by the type of neurological disorder, but are affected by antiepileptic use. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry (UMIN000014179), Date of registration 4 June 2014.

Appropriate head position for nasotracheal intubation by using lightwand device (Trachlight).

The purpose of this study was to determine the relationship between the head position and the subsequent ease of nasotracheal intubation by using the lightwand device Trachlight (TL). Patients requiring nasotracheal intubation were subdivided into 3 groups according to the intubated head position (group S: sniffing position; group E: extension position; and group N: neutral position). The number of attempts, the total intubation time, and the failures of the TL intubation were recorded. Intubation difficulty by means of TL was assessed by the ordinal 6-point scale. Of the 300 patients enrolled in the study, TL intubation was successful in 91.3% of them. There was no significant difference in the success rate of the first attempt between the groups. No correlation between the ordinal scale and the head position was observed. The total intubation time and the ratio of "unsuccessful" cases were not significantly different among the 3 groups. TL is an effective alternative for patients who require nasotracheal intubation. Our study did not determine the most favorable head position for nasotracheal intubation with the TL, so we recommend that nasotracheal intubation with TL be started with the head in the neutral position and then changed to a more appropriate position, if necessary, on an individual basis.

A styletted tracheal tube with a posterior-facing bevel reduces epistaxis during nasal intubation: a randomized trial.

PURPOSE: Epistaxis is a common complication of nasal intubation. Ease of insertion of the tracheal tube may be influenced by bevel orientation and tip bending. We examined ease of insertion and epistaxis with two tubes with different orientations and with or without a stylet to modify tip bending. METHODS: Two hundred patients scheduled to undergo oral or maxillofacial surgery were randomized into four groups according to method of nasal intubation used after induction of anesthesia. In one group, a Portex(®) tracheal tube was inserted with bevel facing left (Portex Group). In the second group, a Parker Flex-Tip(®) tube (Parker Group) was inserted with the bevel facing posteriorly, and in the last two groups, a stylet bent at 60° anteriorly was used with the Portex tube (Stylet-Portex Group) or Parker tube (Stylet-Parker Group). When the tube advanced without resistance, insertion was defined as "smooth", and when resistance was encountered, insertion was defined as "impinged". Severity of epistaxis was evaluated as none, mild, moderate, or severe. RESULTS: Smooth insertion was observed in 60% of patients in the Portex Group; 80% in the Parker Group; 100% in the Stylet-Portex Group; and 100% in the Stylet-Parker Group. Epistaxis was found in 50%, 24%, 20%, and 4% of patients, respectively. The styletted tip (difference: 30%; 95% confidence interval [CI]: 20.3 to 38.5; P < 0.0001) was found to improve ease of insertion. Both the posterior-facing bevel (difference: 21%; 95% CI: 9.0 to 32.1; P = 0.0005) and stylet (difference: 25%; 95% CI: 13.1 to 35.9; P < 0.0001) contributed significantly to absence of epistaxis. CONCLUSIONS: Using a styletted tracheal tube with a posterior-facing bevel improves ease of insertion through the nasopharynx and decreases the severity of epistaxis during nasal intubation. CLINICAL TRIAL REGISTRATION NUMBER: UMIN Clinical Trials Registry (UMIN-CTR), UMIN000011327.

Associations between the autonomic nervous system and the second derivative of the finger photoplethysmogram indices.

AIM: The indices of the second derivative of the finger photoplethysmogram(SDPTG) denote stiffness of large arteries, peripheral vascular resistance and vascular aging. However, the association between the autonomic nervous activity and the SDPTG indices has not yet been elucidated. METHODS: The SDPTG and heart rate variability(HRV) were consecutively measured in the sitting position on the day before surgery in 168 patients 18-89 years of age. The relationships between the SDPTG indices(b/a, c/a, d/a and e/a) and HRV indices(power spectral analysis and time domain analysis parameters) were analyzed. The relationships between c/a and atherosclerosis-based conditions and risk factors for atherosclerosis were also evaluated. RESULTS: The SDPTG index b/a was negatively associated and the d/a index was positively associated with the low-frequency(LF)(R=-0.44 and 0.42, respectively) and high-frequency(HF) components(R=-0.31 and 0.35, respectively). The SDPTG index c/a was also positively associated with the LF(R=0.40) and HF(R=0.44) components. A multivariate regression analysis showed that the LF, HF and heart rate were independent determinants of the c/a. Furthermore, the c/a values were significantly lower in the patients with hypertension, diabetes mellitus and hyperlipidemia than in those without these diseases, and a reduced c/a was significantly associated with increased serum triglyceride and total cholesterol concentrations. CONCLUSIONS: These findings suggest that a decrease in c/a is associated with a reduced baroreflex response of the peripheral vasomotor activity and a decreased cardiac parasympathetic activity. Furthermore, a decrease in c/a was found to be associated with atherosclerosis-based conditions, such as hypertension, diabetes mellitus and hyperlipidemia.

Dexmedetomidine dose-dependently enhances local anesthetic action of lidocaine.

PURPOSE: The combination of α2-adrenoceptor agonists, such as dexmedetomidine (DEX) and clonidine, with local anesthetics has been found to extend the duration of peripheral nerve blocks, probably owing to the resultant local vasoconstriction in the peripheral nerves. However, because the clear elucidation of the effect of DEX requires examination of the local anesthetic effect with DEX alone and the combination of various concentrations of DEX with local anesthetics, we evaluated the local anesthetic effect of various concentrations of DEX alone and with a local anesthetic. MATERIALS AND METHODS: The present study assessed the tail-flick (TF) latencies after injection of the appropriate drug in male Sprague-Dawley rats, using an epidural model that allowed constant pain stimulation intensity, dispersion of the anesthetic, and a precise injection site and dose. Lidocaine alone, lidocaine with 2.5-ppm DEX, lidocaine with 5.0-ppm DEX, lidocaine with 7.5-ppm DEX, and DEX alone were administered at the predetermined dose. The TF latency changes over time were compared using repeated measures analysis of variance (ANOVA). Comparisons among the groups were analyzed using ANOVA followed by a post hoc Dunnett's multiple comparison test or Tukey's multiple comparison test. RESULTS: The addition of DEX to lidocaine increased the TF latency and dose-dependently prolonged its duration as follows: 0-ppm DEX, 20 minutes; 2.5-ppm, 40 minutes; 5.0-ppm, 40 minutes; and 7.5-ppm, 50 minutes. DEX alone did not change the TF latency. CONCLUSIONS: Our results have demonstrated that DEX dose-dependently enhances the local anesthetic action of lidocaine in a rat TF model.

[A case of tracheal intubation for apnea with epidural opioid in recovery room after operation under general anesthesia].

We report a 68-year-old, American Society of Anesthesiologists Class I (ASA I), female patient scheduled for malignant uterine adnexal tumor surgery and revascularization for ovarian cancer. An epidural catheter was inserted at T12-L1 for 5 cm. Anesthesia was induced with remifentanil (0.25 microg x kg(-1) x min(-1)), sevoflurane (5%) and rocuronium (30 mg). Anesthesia was satisfactorily maintained after intubation with sevoflurane (1.5%) and remifentanil (0.2 microg x kg(-1) x min(-1)). We extubated the patient because spontaneous breathing and consciousness were observed. We intubated the patient immediately for apnea that occurred after extubation. The patient made an uneventful recovery after naloxone administration. In pharmacokinetic simulation, on the assumption that epidural administrated fentanyl was carried to blood content promptly, effect concentration to cause respiratory depression was not reached. Postoperative apnea was rationalized as follows; tardy respiratory depression with the epidural administration, and unexpected dosage of the residual fentanyl in the catheter.

Features of lateral cephalograms associated with difficult laryngoscopy in Japanese children undergoing oral and maxillofacial surgery.

BACKGROUND: Difficult laryngoscopy and tracheal intubation are occasionally encountered in children with congenital anomalies or micrognathia. However, no study has elucidated anatomical etiology in relation to craniofacial development. METHODS: Two hundred ten patients aged 8 months-18 years were analyzed. We analyzed the lateral cephalograms of: (i) eight patients in whom laryngoscopy was anticipated as difficult before anesthesia and who were unable to be intubated by direct laryngoscopy and needed fiberoptic bronchoscopy (group A); (ii) 11 patients in whom laryngoscopy was anticipated as difficult before anesthesia but who were able to be intubated by direct laryngoscopy (group B); and (iii) 191 patients in whom laryngoscopy was anticipated as easy before anesthesia and was actually found to be easy (group C). Eight cephalometric parameters were measured and age-parameter relationships were plotted. Logistic regression analysis was performed to characterize group A children for each of the cephalometric variables. RESULTS: Apparently insufficient growth of the mandible was observed in the group A children. Furthermore, the group A children of aged <4 years had undeveloped maxilla, longer mandibular plane-hyoid distances (≥1.3 cm), and deeper depth of the oropharynx; those of aged ≥4 years showed increased inclination of the mandible (sella-nasion plane to mandibular plane angle of ≥46.5°). CONCLUSIONS: Difficult laryngoscopy and tracheal intubation are expected in children aged <4 years with lower-positioned hyoid bone caused by caudal larynx as well as undeveloped maxilla and mandible, and in those aged ≥4 years with increased inclination of the mandible as well as undeveloped mandible.

Establishment of an animal model of sedation using epidural anesthesia that uses the tail-flick test for evaluating local anesthetic effects in rats.

The tail-flick (TF) test is the most frequently used method to measure pain levels and assess the effects of anesthesia. In this study, we performed the TF test in rats sedated via an indwelling epidural catheter and then examined the effectiveness of this method in evaluating the local anesthetic effects. First, an epidural catheter was inserted into the epidural space, and anesthetic [lidocaine (L) or lidocaine including adrenaline (AL)] or normal saline (NS) was administered. Under sedation, we measured the dose for disappearance of the TF response, time to TF response recovery, onset and regression of local anesthesia, as well as the effect of an added agent on its continuation. The time course of TF latency (% maximum possible effect) in the NS group did not change during the experiment. In the AL group, TF latency increased significantly more than baseline during the 30-min period after injection. This was also significantly higher than the latency in the NS group and the L group. In the L group, the TF latency increased significantly above baseline for 20 min after injection and was significantly higher than that in the NS group. Due to the fact that we were able to detect the effect of local anesthesia onset and regression, as well as the local anesthesia continuation action of an additive agent, in rats sedated via an indwelled epidural catheter, we consider our method to be an improvement over conventional methods.

Unrecognized bronchial intubation associated with the uncuffed pediatric tracheal tube with bilateral Murphy eyes.

BACKGROUND: Unreliability of breath sounds auscultation after intubation is reportedly mainly related to the presence of the Murphy eye. This study was performed to ascertain whether an uncuffed pediatric tracheal tube with bilateral Murphy eyes increases the risk of unrecognized bronchial intubation, compared to an uncuffed tube without eyes. METHODS: Following induction of anesthesia in 50 toddlers, either an uncuffed tube without eyes or an uncuffed tube with bilateral eyes was inserted into the trachea. The tube was then slowly advanced while breath sounds were auscultated using a stethoscope. In study 1, when breath sounds changed and disappeared, the distance from the carina to the tube tip was measured using a fiberoptic bronchoscope. In study 2, when breath sounds changed, the tracheal tube was withdrawn 5, 10, 15 and 20 mm while using a fiberoptic bronchoscope to ascertain whether bronchial intubation had occurred. RESULTS: When breath sounds changed and disappeared, the tip of the tube with bilateral eyes was positioned more deeply below the carina than that of the tube without eyes. When the tube was withdrawn 10 mm from the point at which breath sounds changed, frequencies of bronchial intubation were 13% and 80% in the no eyes and double eyes groups, respectively. CONCLUSION: An uncuffed pediatric tracheal tube with bilateral Murphy eyes reduces the ability of breath sounds auscultation to detect bronchial intubation and may increase the risk of unrecognized bronchial intubation compared to an uncuffed tube without eyes.

Preoperative autologous blood donation and acute normovolemic hemodilution affect intraoperative blood loss during sagittal split ramus osteotomy.

INTRODUCTION: This study aimed to determine the effects of acute normovolemic hemodilution (ANH) using low-molecular-weight hydroxyethyl starch (LMW-HES) on intraoperative blood loss in patients who had received preoperative autologous blood donation (PABD) and had undergone sagittal split ramus osteotomy (SSRO). METHODS: Patients who had undergone SSRO were analyzed. All 250 patients received PABD of 400-800 mL until 2 weeks before surgery. ANH was performed by withdrawing whole blood, which was replaced by the same volume of LMW-HES. ANH was performed in 197 cases for 200 mL replacement (ANH-200) and in 5 cases for 400 mL replacement (ANH-400); it was not performed in 48 cases (ANH-0). RESULTS: Blood loss in ANH-200 was greater than that in ANH-0, despite no differences in hemoglobin concentrations at pre- and post-PABD, prothrombin time, activated partial thromboplastin time, fibrinogen and platelet counts between the groups before surgery. Blood loss increased as the total withdrawn blood (sum of PABD and ANH) increased. CONCLUSION: Increased intraoperative blood loss was associated with total withdrawn blood before the operation as well as ANH.

A morphological analysis of thalamocortical axon fibers of rat posterior thalamic nuclei: a single neuron tracing study with viral vectors.

The rostral sector of the posterior thalamic nuclei (POm) is, together with the ventral posterior nuclei (VP), involved in somatosensory information processing in rodents. The POm receives inputs from the spinal cord and trigeminal nuclei and projects to the primary somatosensory (S1) cortex and other cortical areas. Although thalamocortical axons of single VP neurons are well known to innervate layer (L) 4 of the S1 cortex with distinct columnar organization, those of POm neurons have not been elucidated yet. In the present study, we investigated complete axonal and dendritic arborizations of single POm neurons in rats by visualizing the processes with Sindbis viruses expressing membrane-targeted fluorescent protein. When we divided the POm into anterior and posterior parts according to calbindin immunoreactivity, dendrites of posterior POm neurons were wider but less numerous than those of anterior neurons. More interestingly, axon fibers of anterior POm neurons were preferentially distributed in L5 of the S1 cortex, whereas those of posterior neurons were principally spread in L1 with wider and sparser arborization than those of anterior neurons. These results suggest that the POm is functionally segregated into anterior and posterior parts and that the 2 parts may play different roles in somatosensory information processing.