Comparison of the laryngoscopy views with the size 1 Miller and Macintosh laryngoscope blades lifting the epiglottis or the base of the tongue in infants and children <2 yr of age.

BACKGROUND: Miller laryngoscope blades are preferred for laryngoscopy in infants and children <2 yr of age. Despite their long history, the laryngeal view with the Miller blade size 1 has never been compared with that with the Macintosh (MAC) blade in children. This prospective, single-blinded, randomized study was designed to compare the laryngeal views with the size 1 Miller and MAC blades in children <2 yr. METHODS: With IRB approval, 50 ASA I and II children <2 yr undergoing elective surgery were enrolled. After an inhalation induction and neuromuscular block with i.v. rocuronium 0.5 mg kg(-1), two laryngeal views were obtained with a single blade (Miller or MAC) in each child: one lifting the epiglottis and another lifting the tongue base. The best laryngeal views in each blade position were photographed with a SONY(®) Cyber-shot camera and rated by a blinded anaesthesiologist using the percentage of glottic opening scale. RESULTS: The scores with the Miller blade lifting the epiglottis and the MAC blade lifting the tongue base were similar. The scores with the Miller blade lifting the epiglottis and the tongue base were similar. The scores for the MAC blade lifting the tongue base were greater than those lifting the epiglottis (95% confidence interval: 7.6-26.8) (P=0.0004). CONCLUSIONS: In infants and children <2 yr of age, optimal laryngeal views may be obtained with either the Miller size 1 blade lifting the epiglottis or with the Miller or MAC blades lifting the tongue base. CLINICAL TRIAL REGISTRATION: NCT01717872 at Clinical Trials.gov.

Perioperative management of the paediatric patient with coexisting neuromuscular disease.

Children with neuromuscular diseases present a wide range of clinical manifestations and clinical implications for the anaesthesiologist. Neuromuscular diseases in children affect muscle strength by either directly weakening the muscle fibrils or indirectly by a degenerative nerve supply and weak neuromuscular junction. Of the more than 200 neuromuscular disorders known, the vast majority are genetic in origin. This review focuses on four of the more common neuromuscular disorders with emphasis on their pathophysiology and clinical implications for anaesthesiologists: malignant hyperthermia, the muscular dystrophies (Duchenne's, Becker's, and Emery-Dreifuss), mitochondrial disorders, and cerebral palsy.

Perceptual and acoustic evaluation of individuals with laryngopharyngeal reflux pre- and post-treatment.

Thirteen individuals with laryngopharyngeal reflux (LPR) were studied pre- and post-treatment. The effect of treatment on perceptual ratings of voice quality and frequency and intensity measures was examined. Relationships between perceptual and acoustic parameters were assessed descriptively. Results showed a small, but significant improvement in the perception of voice quality post-treatment. No significant differences were found between pre- and post-treatment means for any of the acoustic measures except harmonics-to-noise ratio (HNR). Descriptive analyses showed some association between perceptual ratings and acoustic measures. Discussion of results focuses on severity of LPR.

Open versus closed halo rings: comparison of fixation strengths.

STUDY DESIGN AND OBJECTIVE: A mechanical skull model was used to compare axial loads to failure for three marketed and one experimental halo ring. SUMMARY OF BACKGROUND DATA: Open-back halo rings have become increasingly popular; however, to the authors' best knowledge the literature provides no comparison of the fixation strength of an open-back halo versus the traditional closed design. METHODS: A model biomechanically similar to a human skull was used to compare the axial force necessary to distract each of four halo rings to failure. Three clinically used halo rings were compared: a closed titanium ring, an open titanium ring, and an open graphite ring. One additional open titanium halo ring was constructed with an angular profile; this ring was compared with the clinically used halos. RESULTS: The mean force to failure for the closed titanium ring significantly exceeded that for the open rings (P < 0.005). No significant differences were noted among the open halo rings. DISCUSSION: The data obtained by use of this biomechanical model show that the closed halo ring provides distraction strength greater than that of the open rings, suggesting a more rigid system with the closed device. Use of an angular halo did not improve fixation strength in the open ring device. These findings may support use of a closed halo ring in cervical spine traction and immobilization, if this greater strength is shown to be sufficiently clinically important to offset any disadvantages of a closed ring.

An evaluation of the quality of clinical trials in anesthesia.

BACKGROUND: The authors evaluated the quality of clinical trials published in four anesthesia journals during the 20-yr period from 1981-2000. METHODS: Trials published in four major anesthesia journals during the periods 1981-1985, 1991-1995, and the first 6 months of 2000 were grouped according to journal and year. Using random number tables, four trials were selected from all of the eligible clinical trials in each journal in each year for the periods 1981-1985 and 1991-1995, and five trials were selected from all of the trials in each journal in the first 6 months of 2000. Methods and results sections from the 160 trials from 1981-1985 and 1991-1995 were randomly ordered and distributed to three of the authors for blinded review of the quality of the study design according to 10 predetermined criteria (weighted equally, maximum score of 10): informed consent and ethics approval, eligibility criteria, sample size calculation, random allocation, method of randomization, blind assessment of outcome, adverse outcomes, statistical analysis, type I error, and type II error. After these trials were evaluated, 20 trials from the first 6 months of 2000 were randomly ordered, distributed, and evaluated as described. RESULTS: The mean (+/- SD) analysis scores pooled for the four journals increased from 5.5 +/- 1.4 in 1981-1985 to 7.0 +/- 1.1 in 1991-1995 (P < 0.00001) and to 7.8 +/- 1.5 in 2000. For 7 of the 10 criteria, the percentage of trials from the four journals that fulfilled the criteria increased significantly between 1981-1985 and 1991-1995. During the 20-yr period, the reporting of sample size calculation and method of randomization increased threefold to fourfold, whereas the frequency of type I statistical errors remained unchanged. CONCLUSION: Although the quality of clinical trials in four major anesthesia journals has increased steadily during the past two decades, specific areas of trial methodology require further attention.

Partial tears of the distal biceps tendon: MR appearance and associated clinical findings.

PURPOSE: To describe the magnetic resonance (MR) appearance and associated clinical findings of partial distal biceps tendon tears. DESIGN: Twenty elbow MR images at 1.5 T, performed over a 7 year period, were reviewed for an appearance of partial tears in the distal biceps. These images were assessed by two musculoskeletal radiologists for the extent of: (a) abnormal signal intensity within the tendon, and the presence of (b) bicipitoradial bursitis, and (c) bony microavulsive injury of the radial tuberosity. Medical records for nine of the 20 cases were reviewed for the clinical findings of ecchymosis, trauma, sensation of a "pop", loss of function, and acuity of onset. RESULTS: Twenty partial distal biceps tendon tears were seen. All displayed an abnormally increased signal in the distal biceps tendon. Three of 20 (15%) showed a 25% to 50% tear, ten of 20 (50%) showed a 50% tear, and seven of 20 (35%) showed a 75% to 90% tear. Bicipitoradial bursitis was seen in 11 of 20 (55%) cases. Bony microavulsive injury of the radial tuberosity was observed in 10 of 20 (50%). Of the nine cases reviewed for associated clinical findings, surprisingly, only three (33%) experienced an acute traumatic episode with an abrupt onset of pain. An insidious onset was reported in four of nine (44%). Sensation of a "pop" was recorded in only two of nine (22%) cases. Ecchymosis and loss of function were not seen in any of the cases. Finally, surgical conformation was obtained for three cases. CONCLUSION: Partial distal biceps tendon tears have a characteristic MR appearance, demonstrate little functional deficit, and may be attritional in their etiology due to the observation of a low number of patients reporting trauma or an acute onset.

Can pediatric anesthesiologists detect an occluded tracheal tube in neonates?

UNLABELLED: To determine whether pediatric anesthesiologists can reliably detect occluded tracheal tubes, 18 pediatric anesthesiologists who were blindfolded and fitted with earplugs manually ventilated the lungs of 16 neonates. Consent was obtained from the parents of the neonates. All auditory signals from the monitors were silenced. Six conditions were studied (for 3 min each) in random order: three models of Ayre's t-piece with the Jackson Rees modification and two fresh gas flows (FGF) (2 and 6 L/min). During each condition, the tracheal tube was clamped at five predetermined but randomized times. The volume/pressure relationships of the three t-piece models were determined. Tube occlusions were detected more frequently at a low FGF (82%) than at a high FGF (64%) (P < 0.001). Experienced anesthesiologists (>8 yr experience) detected occlusions (83%) more frequently than less experienced (<2 yr experience) anesthesiologists (63%) (P < 0.027). There was no interaction between FGF and experience. The type of circuit did not affect the detection rate. We conclude that during isolated hand ventilation with the t-piece, pediatric anesthesiologists can detect >80% of occluded tubes provided they use a low FGF or have >8 yr experience, but only 60% of occluded tubes at high FGF or if they have <2 yr experience. IMPLICATIONS: Hand ventilation of the lungs in neonates has been used to detect changes in respiratory compliance, but laboratory models have failed to demonstrate its usefulness. We determined that pediatric anesthesiologists could detect 83% of tracheal tube occlusions in neonates if either the fresh gas flow was 2 L/minor the pediatric anesthesiologist was experienced (> 8 yr).

Penetration of cranial inner table with Gardner-Wells tongs.

The compression force exerted by Gardner-Wells tongs was compared with the force necessary to penetrate the cranial inner table with a Gardner-Wells tong pin. Load cells measured the force exerted by the spring-loaded Gardner-Wells tong pin on fresh cadaveric skull samples. Increasing forces were exerted until penetration of the inner table occurred. At the manufacturer's recommended, 1 mm indicator stem protrusion an average of 30 pounds of compressive force was exerted by the spring-loaded pin. The average force necessary to penetrate the inner table with the cadaveric specimens with the tong pin was 162 pounds. The force necessary to penetrate the inner table of the skull well exceeds that exerted by properly applied tongs, suggesting that the risk of inner table penetration is low.

Dimensions of the left ventricle, atrium, and aortic root in pregnancy-induced hypertension.

Chronic hypertension induces changes in the structure of the left ventricle, atrium, and aortic root. However, the effects of transient hypertension are unclear. Pregnancy-induced hypertension (PIH) offers a natural and spontaneous model of this condition. Using M-mode echocardiography, we studied 95 consecutive patients with PIH, who were compared with 83 normal pregnant women (NPW). We evaluated diastolic diameter (DD), systolic diameter (SD), septal thickness (ST), posterior wall thickness (PWT), shortening fraction (SF), relative wall thickness (RWT), left ventricular mass index (LVMI), left atrial dimension (LAD), and aortic root dimension (ARD). Patients with PIH had higher ST (9.98 +/- 1.47 mm v 8.96 +/- 1.43 mm, P < .000), PWT (9.28 +/- 1.48 mm v 8.55 +/- 1.35 mm, P < .000), LVMI (107.65 +/- 27.87 g/m2 v 92.38 +/- 17.99 g/m2, P < .000), and RWT (0.406 +/- 0.06 v 0.377 +/- 0.06 mm, P < .002). There were no significant differences in DD, SD, SF, LAD, and ARD. In conclusion, PIH increases the LVMI due to an increase in the ST and PWT. The dimensions of the left ventricle, left atrium, and aortic root do not change.

Early failure of Pavlik harness treatment for developmental hip dysplasia: clinical and ultrasound predictors.

A cohort of 93 patients with developmental dysplasia of the hip (DDH) treated with a Pavlik harness were evaluated to determine predictors of treatment failure. Failure was defined as failure to achieve or maintain hip reduction in the Pavlik harness. Of 93 patients (137 hips), 17 (26 hips) failed Pavlik harness treatment. Univariate risk factors for failure included bilaterality, initial clinical exam, and initial ultrasound (US) percent coverage. Clinical exam and initial percent coverage were multivariate risk factors for failure. Among initially clinically dislocatable hips, a low initial US alpha angle correlated with an increased likelihood of failure. All (6/6) patients with an initially irreducible hip and an initial coverage of <20% by US eventually failed treatment. Gender, side of pathology, and age at diagnosis and initiation of treatment did not correlate with failure. Irreducibility by physical exam combined with US coverage of <20% identified a patient group that uniformly failed Pavlik harness treatment. These patients may be candidates for alternative bracing, traction, or closed or open reduction.

Left ventricular function impairment in pregnancy-induced hypertension.

The changes induced by transient hypertension on cardiac structure and function are unclear. Pregnancy-induced hypertension offers a natural and spontaneous model of this condition. To assess the potential of echocardiographic Doppler to unmask left ventricular function impairment, we studied 28 women aged 26.4 +/- 7.2 years with pregnancy-induced hypertension defined as blood pressure higher than 140/90 mm Hg in the third trimester of pregnancy without a history of hypertension. Twenty normal pregnant women, aged 27.5 +/- 6.4 years, were the controls. Left ventricular diastolic diameter, fractional shortening, E velocity, A velocity, E/A ratio, isovolumetric relaxation time (IRT), isovolumetric contraction time (ICT), ejection time (ET), and the combined index of myocardial performance (Tei index = IRT + ICT/ET), were calculated by echocardiography Doppler 2 to 4 days postpartum. There were statistically significant differences between groups in the following parameters: E/A ratio: 1.3 +/- 0.3 in pregnancy-induced hypertension v 1.5 +/- 0.3 in normal pregnant women (P < .05), IRT: 104 +/- 14 msec v 84 +/- 7 msec (P < .000), and the Tei index: 0.51 +/- 0.15 v 0.35 +/- 0.04 (P < .00), respectively. According to this data pregnancy-induced hypertension evaluated 2 to 4 days after delivery showed left ventricular dysfunction, mainly diastolic. The IRT and the Tei index are the most useful echocardiographic parameters to unmask left ventricular dysfunction in pregnancy-induced hypertension.

A study of sentence stress production in Mandarin speakers of American English.

Acoustic characteristics of American English sentence stress produced by native Mandarin speakers are reported. Fundamental frequency (F0), vowel duration, and vowel intensity in the sentence-level stress produced by 40 Mandarin speakers were compared to those of 40 American English speakers. Results obtained from two methods of stress calculation indicated that Mandarin speakers of American English are able to differentiate stressed and unstressed words according to features of F0, duration, and intensity. Although the group of Mandarin speakers were able to signal stress in their sentence productions, the acoustic characteristics of stress were not identical to the American speakers. Mandarin speakers were found to produce stressed words with a significantly higher F0 and shorter duration compared to the American speakers. The groups also differed in production of unstressed words with Mandarin speakers using a higher F0 and greater intensity compared to American speakers. Although the acoustic differences observed may reflect an interference of L1 Mandarin in the production of L2 American English, the outcome of this study suggests no critical divergence between these speakers in the way they implement American English sentence stress.

Acoustic comparison of vowel articulation in normal and reverse phonation.

Acoustic characteristics of the vowels /i,u,a/ produced by adult females and males during normal phonation were compared with the same vowels produced on deliberate ingressive airflow (i.e., "reverse" phonation). Results of the analysis revealed the average fundamental frequency (F0) of reverse phonation to be significantly higher than the corresponding normal phonations. There were no significant differences noted in the vocal tract resonance (F1 and F2 frequency) values for /i/ during normal and reverse phonation. However, the F1 values for /a/ were significantly lower, and the F2 values for /u/ significantly higher, during reverse phonation. The results are discussed with regard to differences in the articulatory control of the speech mechanism during reverse phonation as compared to normal expiratory phonation. Also discussed are the implications of using reverse phonation as a voice management technique.

Fundamental frequency, intensity, and vowel duration characteristics related to perception of Cantonese alaryngeal speech.

Fundamental frequency (F(0)), F(0) contours, vowel duration, and intensity associated with Cantonese alaryngeal speech, and their relation to the perception of meaning were studied. Thirty adult male native Cantonese speakers participated in the study: 10 esophageal, 10 electrolaryngeal, and 10 laryngeal speakers. Results indicated that perceptually, listeners were able to identify what the Cantonese esophageal speakers were saying, particularly for words associated with high-level, low-falling and high-rising tonal contours. Acoustic analysis of the speech signals of the esophageal speakers indicated that intensity and durational data did not contribute to the perception of meaning. The F(0) contours appeared to be the acoustic cues associated with the signal that contributed most to the perception of meaning.

An acoustic analysis of excellent female esophageal, tracheoesophageal, and laryngeal speakers.

Acoustic data for female esophageal speakers is sparse, particularly with regard to characteristics of female tracheoesophageal speakers. This study quantified and compared six acoustic characteristics of excellent female tracheoesophageal (TE), standard esophageal (SE), and laryngeal (LA) speakers. Results indicated there were no significant differences between TE and SE speakers with regard to mean F0 of sustained /a/, mean F0 (reading), signal-to-noise ratio, total duration of passage read, number of pauses, or syllables per minute. Significant differences were found between LA speakers and both alaryngeal groups for all variables, with the exception of mean F0 (reading).

Comparison of remifentanil versus regional anaesthesia in children anaesthetised with isoflurane/nitrous oxide. International Remifentanil Paediatric Anaesthesia Study group.

We compared the efficacy and safety of a remifentanil (0.25 microg x kg(-1) x min(-1)-based balanced anaesthetic technique with a bupivacaine-based regional anaesthetic technique in an open label, multicentre study in 271 ASA physical status 1 or 2 children aged 1-12 years. Subjects requiring major intra-abdominal, urological or orthopaedic surgery were randomly allocated to receive either intravenous remifentanil (group R; n = 185) or epidural bupivacaine (group B; n = 86) with isoflurane/nitrous oxide for their anaesthesia. The majority of children in both groups (85% in group R, 78% in group B) showed no defined response to skin incision, and although the mean increase in systolic blood pressure (+11 mm Hg) was significantly greater in group R than in group B, this change did not represent a serious haemodynamic disturbance. More children in group R (31%) required interventions to treat hypotension and/or bradycardia than those in group B (12%), but these were easily managed by administration of fluids or anticholinergic drugs. Adverse events, mainly nausea and/or vomiting, occurred in 45% of group R and 42% of group B (NS). The adverse event profile of remifentanil in this study was typical of a potent mu-opioid receptor agonist. Remifentanil was as effective as epidural or caudal block in providing analgesia and suppressing physiological responses to surgical stimuli in children aged between 1 and 12 years undergoing major abdominal, urological, or orthopaedic surgery under isoflurane/nitrous oxide anaesthesia.