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.

Carbon fixation and isotope discrimination by a crassulacean plant: dependence on the photoperiod.

Variations of more than 1 percent are observed in the carbon-13 to carbon-12 ratio of extracts of leaves of the succulent Kalanchoe blossfeldiana when the photoperiod is changed from long to short days. This indicates that the mechanism of carbon fixation switches from the Calvin (C(3)) pathway to the Hatch-Slack (C(4)) pathway of primary enzymic operation. The variations observed in the isotope compositions are tentatively explained by a model.

Carbon-14 in patagonian tree rings.

The radiocarbon activity found in tree rings from southern Argentina shows secular fluctuations which are synchronous with and of the same amplitude as those known for the Northern Hemisphere. Comparable measurements indicate that the activity in Patagonian trees is about five per mil lower than in European trees.

Effects of age on the serum concentration of alpha 1-acid glycoprotein and the binding of lidocaine in pediatric patients.

We determined the effect of age on the serum concentration of alpha 1-acid glycoprotein (alpha 1-AGP) in venous blood from 134 subjects who ranged in age from preterm neonates to 18-year-old adolescents. The mean (+/- SD) serum concentration of alpha 1-AGP, determined by radial immunodiffusion, increased significantly with age: the concentration found in neonates was less than that found in infants which, in turn, was less than that found in older children (p less than 0.001). In addition, we determined the effect of alpha 1-AGP on the free fraction of lidocaine in four groups of infants and children who received intravenous lidocaine (1.5 mg/kg). The percentage of free lidocaine correlated inversely and linearly with the serum alpha 1-AGP concentration (r2 = 0.617; p less than 0.001). The percentage of free lidocaine in the five neonates exceeded that in the older age groups. We conclude that the serum concentration of alpha 1-AGP increases while the free fraction of lidocaine decreases from early infancy to adolescence.

Pharmacokinetics of intravenous ondansetron in healthy children undergoing ear, nose, and throat surgery.

BACKGROUND: To determine the pharmacokinetics of the 5-HT3 antagonist ondansetron in children, informed written consent was obtained from the parents of 21 healthy children aged from 3 to 12 years scheduled for ear, nose, and throat surgery. METHODS: The children were stratified according to age: 3 to 7 years and 7.1 to 12 years, and a single intravenous infusion of 2 or 4 mg ondansetron, respectively, was administered over 5 minutes before induction of anesthesia. After completion of the infusion, anesthesia was induced intravenously and maintained with inhalational anesthesia. Whole blood (3 ml) was obtained before administration of ondansetron, at completion of the infusion, at the beginning and end of surgery, and at 3, 4, 6, 8, 10, and 12 hours after start of the infusion. Pharmacokinetic variables were determined with use of standard noncompartmental techniques. RESULTS: Mean plasma clearance was 0.50 L.hr-1.kg-1 and 0.39 L.hr-1.kg-1, the mean volume of distribution at steady-state was 1.70 L.kg-1 and 1.61 L.kg-1, and the mean plasma terminal half-life was 2.6 hours and 3.1 hours for the 2 mg and 4 mg groups, respectively. On a body surface area basis, mean plasma clearance was 14.0 and 13.7 L.hr-1.m-2 and mean volume of distribution was 47.7 and 55.9 L.m-2 for the 2 and 4 mg groups, respectively. There were no serious adverse events attributable to ondansetron. CONCLUSIONS: These data indicate that the pharmacokinetics of ondansetron in children from 3 to 12 years old are predictable and similar to those in adults. The elimination half-life of ondansetron increases in parallel with age. However, clearance is constant when normalized to body surface area, but the volume of distribution increases over the age range studied.

Pharmacokinetics of the active metabolite (MDL 74,156) of dolasetron mesylate after oral or intravenous administration to anesthetized children.

BACKGROUND: Dolasetron mesylate is a selective 5-HT3 receptor antagonist under investigation as an antiemetic in children. Published studies indicate that its antiemetic activity results from the active metabolite (MDL 74,156), which is produced within 10 minutes of administration of dolasetron mesylate. METHODS: The pharmacokinetics of MDL 74,156 and the safety and tolerability of dolasetron mesylate were studied after a single oral or intravenous dose of 1.2 mg.kg-1 dolasetron mesylate to healthy children from 2 to 12 years of age. Oral dolasetron was administered to 12 children 1 to 2 hours before anesthesia. Intravenous dolasteron was administered to 18 children at induction of anesthesia. Serial blood samples were collected for 24 hours after dosing to measure the plasma concentration of MDL 74,156. Indexes of liver and kidney function were determined, and electrocardiograms and adverse events were recorded.

Predictive value of changes in R-wave amplitude after exercise in coronary heart disease.

To assess the predictive value of coronary events reflected by changes in R-wave amplitude after exercise, 146 patients with angiographically documented coronary heart disease were studied. All patients were followed up for 6 years, during which time myocardial infarction and death of cardiovascular origin were considered endpoints. The incidence of events in patients in whom R-wave amplitude decreased (normal response) and in those in whom R-wave amplitude did not change or increase (abnormal response) were compared. The incidence of coronary events in patients with a normal response was 23% and in those with an abnormal response, 45.8% (p less than 0.01). Correlating the results with several noninvasive and angiographic variables, an abnormal R-wave response showed a significantly higher rate of events in the subsets of patients with prior myocardial infarction, absence of cardiomegaly, maximal functional capacity lower than 4 METs, maximal heart rate higher than 140 beats/min and abnormal left ventricular function. Thus, the changes in R-wave amplitude after exercise is a variable that should be taken into account when assessing the risk of future events in patients with coronary heart disease.

Doxepin's effects on chronic pain and depression: a controlled study.

Sixty patients with chronic pain of the low back or cervical spine concomitant with clinical depression were studied in a 6-week, randomized, double-blind comparison of doxepin and placebo. Significant improvements in the doxepin-treated group compared to placebo or to baseline values were seen on Hamilton depression scores, Global Assessment Scale scores, pain severity, percent of time pain felt, and effect of pain on activity, sleep, and muscle tension. Some improvements were observed after 1 week of treatment; the most improvement occurred at 6 weeks, when the mean doxepin dosage was approximately 200 mg/day and plasma doxepin and nordoxepin averaged 80 ng/ml. No significant harmful effects were observed. Neither plasma beta-endorphin nor enkephalin-like activity demonstrated significant differences from baseline. These data indicate that doxepin is a valuable treatment for patients with chronic pain and depression.

Dosing efficiency and particle-size characteristics of pressurized metered-dose inhaler aerosols in narrow catheters.

An experimental in vitro model was used to determine the effects of intraluminal catheter diameter and length on the delivered dose and particle-size characteristics of salbutamol (albuterol) aerosol delivered by metered dose inhaler (MDI) (Ventolin, 100 micrograms per puff). The dose of aerosolized drug that exited a 16-cm-long tracheal tube with an inner diameter (ID) of 6 mm was compared with that from 4 catheters of differing diameters and lengths that were inserted individually into the tracheal tube. The salbutamol MDI canister was actuated ten times into each delivery system, and the effluent aerosol was trapped onto a filter. The filtrate was dissolved in methanol, and the salbutamol concentration was determined using high-performance liquid chromatography. For the 3 22-cm-long catheters, the delivered dose (mean +/- SD) of salbutamol per actuation for the 22-standard wire gauge (SWG) catheter was 97.5 +/- 3.9 micrograms, which was similar to that for the 19-SWG catheter (102.3 +/- 2.5 micrograms) but was significantly less than that for the 14-SWG catheter (108.2 +/- 4.2 micrograms) (p < 0.05). These delivered doses exceeded those of the 6.0-mm-ID tracheal tube alone (2.33 +/- 0.76 micrograms) and the 13-cm-long 19-SWG catheter (2.17 +/- 0.29 micrograms) (p < 0.001). In a second experiment using a cascade impactor, the distribution of aerosol particle diameters that exited the 6-mm-ID tracheal tube was compared with that exiting a 13-cm-long 19-SWG catheter that extended halfway down the tracheal tube and with that exiting a 22-cm-long 19-SWG catheter inserted into the distal end of the 6-mm-ID tracheal tube. The mass median aerodynamic diameter (mean +/- SD) of the salbutamol aerosols delivered through both the 6.0-mm-ID tracheal tube (1.1 +/- 0.1 microns) and that of the 13-cm-long 19-SWG catheter (1.2 +/- 0.2 microns) were significantly less than that delivered through the 22-cm-long 19-SWG catheter (2.0 +/- 0.1 microns) (p < 0.05). The authors conclude that delivery of respirable aerosol can occur through narrow catheters that function as extended nozzles for MDIs. Optimal dosing will be obtained when the catheter extends the full length of the tracheal tube.

Effects of nitrates on R-wave variations after exercise in coronary heart disease: differences in patients with and without angina pectoris.

With the purpose of investigating the pathophysiology of changes in the R wave after exercise and its relationship with left ventricular function, we studied 44 patients with coronary heart disease. They were classified into the following three groups: group A, 11 patients with angina pectoris and no prior myocardial infarction; group B, 18 patients with angina pectoris and prior myocardial infarction; and group C, 15 patients with prior myocardial infarction but no angina. All patients performed two exercise tests; one was a control test, and the other was performed after the sublingual administration of 5 mg of isosorbide dinitrate. In group A, variations in the R-wave voltage in control test and in the test after isosorbide dinitrate were 1.5 +/- 0.8 mm and -1.2 +/- 0.9 mm (P less than 0.05), respectively. In group B, results were 1.2 +/- 0.7 mm on the control test and -0.7 +/- 0.6 mm after isosorbide dinitrate (P less than 0.002), and in group C were -1.6 +/- 1.2 mm on the control test and -0.7 +/- 0.7 mm after isosorbide dinitrate (not significant). Thus, the two groups of patients with angina showed an increase of the R-wave after exercise in the control test but a decrease after the administration of nitrates, whereas the patients without angina showed a reduced R-wave after exercise both before and after the administration of nitrates (like normal subjects). This study suggests that ischemic ventricular dysfunction with exercise results in an increase in the R-wave, while exercise after nitrates results in a decrease in the R-wave consistent with less or no ventricular dysfunction due to nitrate therapy.

Metered-dose inhaler salbutamol-induced tracheal epithelial lesions in intubated rabbits. Effects of the site of administration and time.

STUDY OBJECTIVES: To determine (1) whether metered-dose inhaler (MDI) salbutamol administered at the elbow connector of the anesthetic circuit produced tracheal epithelial lesions in intubated rabbits, and (2) the time course for resolution of tracheal lesions produced by MDI salbutamol through an intratracheal catheter. DESIGN: Prospective, randomized, controlled trial. SETTING: University-affiliated animal research laboratory. PARTICIPANTS: Thirty-nine adult New Zealand white rabbits. INTERVENTIONS: (1) Twenty-one intubated rabbits received 0,5, or 20 puffs of MDI salbutamol delivered at the elbow connector of the anesthetic circuit. (2) Eighteen intubated rabbits received five puffs of MDI salbutamol through an intratracheal catheter and were killed 1 h, 24 h, or 1 week later. MEASUREMENTS: Samples of trachea, bronchi, and lungs were examined by light microscopy, and the degree of epithelial injury was assessed semiquantitatively. RESULTS: MDI salbutamol (5 or 20 puffs) administered at the elbow did not induce tracheal epithelial injury. When administered through an intratracheal catheter, MDI salbutamol (five puffs) produced moderate or severe tracheal epithelial injury in those killed 1 h after the study. Evidence of epithelial regeneration was observed 24 h after the injury and recovery was virtually complete by 1 week. CONCLUSION: Epithelial lesions do not occur when the MDI salbutamol (5 or 20 puffs) is administered at the elbow connector of the ventilation circuit. Tracheal epithelial lesions produced by MDI salbutamol (five puffs) administered through an intratracheal catheter resolve within 1 week of the injury.

Left ventricular geometry in pregnancy-induced hypertension.

The changes induced by transient hypertension upon cardiac geometry (G) are unclear. Pregnancy-induced hypertension (PIH) offers a natural and spontaneous model of this condition. To assess geometric changes according to two-dimensionally guided M-mode echocardiography, we compared patients with PIH with normal pregnant women (NPW). Fifty-five women, aged 28.5 +/- 7.5 years, with PIH (defined as blood pressure >140/90 mm Hg in the third trimester of pregnancy and without a history of hypertension) were compared with 57 NPW aged 30.7 +/- 7.5 years. Left ventricular mass index (LVMI) (Devereux formula) and relative wall thickness (RWT) (Ganau formula) were calculated by means of echocardiography done in the left lateral decubitus 2 to 4 days postpartum. Subjects were considered to have: normal geometry (NG) if both LVMI and RWT fell below the mean +/- 1 SD or 2 SD; concentric hypertrophy (CH) if both were elevated; eccentric hypertrophy (EH) if LVMI was elevated and RWT was normal; and concentric remodeling (CR) if LVMI was normal and RWT was elevated. Comparisons were performed by the Student t test. Patients with PIH had higher LVMI (106 +/- 29.4 v 90.6 +/- 19.8 g/m2; P < .05) and RWT (0.41 +/- 0.07 v 0.38 +/- 0.05; P < .05). Considering the mean +/- 1 SD of NPW as the limit of normality the G pattern was NG in 26 (47%) and abnormal in 29 (53%), of which 14 (25.5%) had EH, 11 (20%) had CR, and four (7%) had CH. If we considered the mean +/- 2 SD, the G pattern was NG in 46 (84%) and abnormal G in nine (16%), EH in four (7%), CR in three (5%), and CH in 2 (4%). According to these data, women with PIH had higher LVMI and RWT compared with NPW. The most frequent abnormal G patterns were EH and CR.

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.

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.

The effects of buspirone on sleep in the rat.

Buspirone is a novel anxiolytic compound that does not produce the sedation often associated with the use of benzodiazepines. The present study evaluated the effects of this anxiolytic on sleep in rats surgically prepared for long-term recordings. Buspirone, at a dose of 3 mg/kg i.p., produced a significant increase in total wake time (P less than 0.05) compared with drug-free controls. At a dose of 10 mg/kg i.p., rats displayed altered sleep patterns with the most significant effects observed in the first third of recording period. These animals displayed increased wakefulness (P less than 0.001), decreased non-REM sleep (P less than 0.001), and an obliteration of REM sleep (P less than 0.02). These data support the suggestion that the clinically useful anxiolytic buspirone, unlike the benzodiazepines, does not induce sleep.

Usefulness of echocardiography and doppler echocardiography in endomyocardial fibrosis.

OBJECTIVE: Our goal was to demonstrate the usefulness of echocardiography and cardiac Doppler echocardiography (echo-Doppler) in the diagnosis of endomyocardial fibrosis, an unusual restrictive cardiomyopathy in Argentina. METHODS: Between 1980 and 1998, we studied 10 women (aged 27 to 58 years) with endomyocardial fibrosis confirmed by surgery and/or endomyocardial biopsy. Of the 10 cases of endomyocardial fibrothrombosis, 8 were biventricular and 2 were left ventricular. Six patients had only an echocardiographic study, and the last 4 patients (after 1987) had an echo-Doppler study also; 3 had a transesophageal echocardiography examination as well. Seven patients had grade III-IV dyspnea, 2 had an edematous-ascitic syndrome, and 1 had right heart failure at the first examination. Four patients died of heart failure and 1 of overimposed sepsis. Surgery was successful in 2 patients with the biventricular form of the disease. In one of them, fibrotic decortication was performed in both ventricles together with tricuspid and mitral replacement. In the other, the right side was not surgically treated because of its mild engagement. One patient was lost to follow-up, and 3 patients are awaiting surgery at this writing. RESULTS: In all 10 patients, echocardiography was the first diagnostic tool used. In M-mode echocardiography, the typical image showed the "square root" sign in the septum and posterior wall in addition to the "merlon" sign, characterized by a hypercontractile basal ventricle opposing an obliterated apex. In 2-dimensional echocardiography, inversion of the normal sized heart with obliterated ventricles and dilated atria were seen in the whole group. In 1 patient, the fibrous thrombus was limited to the apex of the right ventricle (Shaper's type 1) in a biventricular form, whereas in the left side of this patient and in the other 9 patients, the fibrous thrombus that initially occupied the apex engaged the posterior papillary muscle, pulling the posterior valve downward (Shaper's type 2) and generating tricuspid and/or mitral regurgitation that was always mild or moderate. The fibrous thrombus never altered the movement of the underlying myocardium. There were hypoechoic and hyperdense echoes inside the fibrotic material (the latter compatible with calcium), and in all 10 patients, different grades of pericardial effusion were found. Echo-Doppler showed the same minimal percentage of change in mitral and tricuspid velocities as found in healthy patients, which clearly differentiates endomyocardial fibrosis from constrictive pericarditis. Furthermore, a restrictive pattern was observed on both atrioventricular valves when both sides were engaged with a markedly short tricuspid deceleration time. Pulmonary veins showed a markedly diastolic D wave and a broad reversal A wave (the latter presented a low velocity when the wall of the left atrium was diseased) caused by an increased end-diastolic left ventricular pressure to the same extent throughout the respiratory cycle. Hepatic veins showed a markedly deep diastolic forward wave throughout the respiratory cycle and a marked reversal with inspiration. CONCLUSIONS: We showed (1) echocardiographic studies of a significant number of patients with this unusual disease, (2) the characteristic diagnostic signs in M-mode and 2-dimensional echocardiography, and (3) the common echo-Doppler patterns shared by all subjects studied with this technique.

Effect of left and right lateral decubitus positions on Doppler mitral flow patterns in patients with severe congestive heart failure.

Patients with severe congestive heart failure (SCHF) complain of increasing dyspnea when adopting left lateral decubitus (LLD) position that improves when turning over to the right lateral decubitus (RLD) position (trepopnea). We hypothesize that this clinical sign is due to changes in left ventricular (LV) preload and such changes would modify mitral flow. This study analyzes the effect of RLD and LLD positions on LV filling pattern assessed by Doppler echocardiography in patients with SCHF. Seventeen men and seven women (aged 56.22 +/- 18.52 years) with SCHF in New York Heart Association functional class III-IV and nine normal control subjects (eight men and one woman aged 56.96 +/- 18.14 years) were studied. We analyzed early (E) and late (A) LV filling velocities, E/A ratios, deceleration time, mitral time-velocity integral in each decubitus position, and the differences between them. Patients with SCHF have smaller mitral time-velocity integral, shorter deceleration time, greater E velocity and E/A ratio, and lower A velocity in LLD position than do normal control subjects. On assuming RLD position, patients with SCHF show decreases in E velocity and E/A ratio and lengthening of the deceleration time, suggesting a decrease in LV preload on changing position. This pathophysiologic mechanism may explain why patients with SCHF willingly adopt RLD position.