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Flexible laryngoscopy in neonates and infants: insertion through a median opening in the face mask.

The most common reasons for laryngoscopy in newborns and infants are inspiratory stridor and/or dyspnea. With the help of flexible endoscopes, especially with instruments of diminished diameter, laryngoscopy can be carried out even in premature newborns. We report on a technique of flexible laryngoscopy without the need for restraint and with improved safety. A modified face mask is used for endoscopy. An additional hole is made into the mask with a 4.5 mm drill. It is located in the midline just above the nostrils, about 2.5 cm above the ventilation opening. The flexible endoscope is passed into the nose and pharynx with ease. It does not interfere with the anesthetist's ventilation by the mask. In inhalation anesthesia with halothane, 100% oxygen is supplied. The larynx remains in its physiological position. The head is not retroflexed, and the tongue is not supported by an endoscope as in direct laryngoscopy. No muscle relaxation is used, and muscular activity of the larynx can be observed during spontaneous and assisted ventilation.

Anesthesia, Inhalation↗

Airway involvement and anesthetic management in Goltz's syndrome.

A 13-year-old girl with Goltz's (Goltz-Gorlin) syndrome (focal dermal hypoplasia) and cloacal exstrophy underwent day surgery cystoscopy. During the administration of inhalation anesthesia by mask, persistent partial upper airway obstruction was noted. Direct laryngoscopy unexpectedly showed variously sized verrucous lesions in the hypopharynx and supraglottic larynx, and the vocal cords and trachea could not be visualized. The patient later returned for a complete endoscopic examination, followed by cup forcep and laser excision of these verrucous and pedunculated lesions, and remained intubated in the intensive care unit (ICU) for 48 hours following this procedure. Airway management and pathology specific to this rare disorder are discussed.

Adolescent↗

Should the gas outlet port on membrane oxygenators be routinely scavenged during cardiopulmonary bypass?

Elimination of a volatile anesthetic agent administered prior to the start of bypass through the oxygenator has not been previously described. The purpose of this study was to determine the contamination risk from enflurane used before but not during cardiopulmonary bypass. Enflurane concentration was measured from the gas outlet port of a membrane oxygenator using infrared gas analysis in 11 cardiac surgical patients. The mean peak concentration at the gas outlet port in patients who had a final end-tidal concentration of < or = 0.3% was 0.08 +/- 0.04%, compared to 0.18 +/- 0.05% in patients with a final end-tidal concentration of more than 0.3%, P < 0.001. The elapsed time to reach peak concentration was 8.3 +/- 8.4 minutes, whereas the elapsed time from the peak concentration to 50% of the peak level was 63.1 +/- 25.1 minutes. At the time of peak enflurane release, a concentration of less than 2 ppm was measured at distances of 10 cm or less from the oxygenator gas outlet port in patients with an end-tidal enflurane of < or = 0.3%. In one patient with a final end-tidal enflurane of 1.1%, a contaminant level of 2 ppm could be measured at 95 cm from the oxygenator gas outlet port. This demonstrates that there is a potential risk of contamination from volatile anesthetics used immediately prior to extracorporeal circulation. Minimizing this risk may necessitate routine scavenging of the oxygenator, or simply avoiding increased concentrations of inhalation anesthesia before initiating cardiopulmonary bypass.

Air Pollutants, Occupational↗

Botulinum toxin management of childhood intermittent exotropia.

OBJECTIVE: Intermittent exotropia is a common form of childhood strabismus that has a late onset and presents a difficult and frustrating management dilemma. Surgical treatments have a high recurrence rate, and multiple surgeries often are required to achieve a desirable motor outcome. This study presents long-term observations on the use of botulinum toxin for the treatment of intermittent exotropia in children. DESIGN: This study is a nonrandomized, case-controlled study of consecutive pediatric patients who had intermittent exotropia. PARTICIPANTS: Thirty-two neurologically normal children ranging from 3 to 144 months in age were diagnosed with intermittent exotropia with a minimum distance deviation of 15 prism diopters (PD). INTERVENTION: Simultaneous bilateral injections of 2.5 units botulinum toxin type A were made into the lateral rectus muscles with the patient receiving nitrous oxide-ethrane inhalation anesthesia. Patients were observed for 12 to 44 months after the initial injection. MAIN OUTCOME MEASURES: A satisfactory outcome was considered to be stable binocular alignment of the eyes to an orthophoric range of +/-10 PD. RESULTS: Bilateral lateral rectus muscle injections of botulinum toxin were effective in reducing the mean preinjection deviation of -29 PD to an average exotropic angle of -6 PD. Stable orthophoria (+/-10 PD) was achieved in 22 patients (69%). Overall, male patients required significantly fewer injections than did female patients. All patients between 24 and 56 months of age, irrespective of gender, required only a single bilateral injection to achieve a favorable motor outcome. CONCLUSIONS: Botulinum toxin is at least as effective as surgical outcomes reported previously for the treatment of intermittent exotropia in children. This treatment method is particularly effective in children between 2 and 4.5 years of age irrespective of the initial strabismic angle and is not associated with any secondary abnormalities.

Anesthesia, Inhalation↗

Postoperative apnea in preterm infants.

Preterm infants may become apneic during the immediate post-operative period. To define this risk, the authors studied prospectively the breathing patterns of 47 preterm infants less than 60 weeks postconception with pneumocardiograms before and after general inhalational anesthesia. Eighteen infants (37%) had prolonged apnea (greater than 15 s) postoperatively, and an additional seven infants (14%) had short apnea (6-15 s) postoperatively. An infant's risk of prolonged and short postoperative apnea was related to a young postconceptional age (P less than 0.05) and to a history of necrotizing enterocolitis (P less than 0.01). Furthermore, as the postconceptional age of the infant increased, the risk of postoperative apnea decreased proportionately (P less than 0.025). Among the 18 infants with prolonged apnea, 83% experienced multiple apneic episodes. Manual stimulation was required in order for breathing to return in 13 (72%) of the infants. Breathing resumed spontaneously in four (22%) of the infants, and one infant required mechanical ventilation due to repeated prolonged apnea. The first apneic event occurred within 2 h postoperatively in 13 of the infants (72%); the remaining five infants (28%) had their initial apneic episode as late as 12 h after operation. The postoperative time to the last prolonged apneic event was inversely related to the postconceptional age (P less than 0.01, r = -0.70) and extended up to 48 h postoperatively. The preoperative pneumocardiogram was not a reliable test for predicting postoperative apnea (sensitivity 56%, specificity 83%).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗

Volume kinetic analysis of the distribution of 0.9% saline in conscious versus isoflurane-anesthetized sheep.

BACKGROUND: The distribution and elimination of 0.9% saline given by intravenous infusion has not been compared between the conscious state and during inhalational anesthesia. METHODS: Six adult sheep received an intravenous infusion of 25 ml/kg of 0.9% saline over 20 min in the conscious state and also during isoflurane anesthesia and mechanical ventilation. The distribution and elimination of infused fluid were studied by volume kinetics based on serial analysis of hemoglobin dilution in arterial blood and by mass balance that incorporated volume calculations derived from volume kinetic analysis and measurements of urinary volumes. RESULTS: The mass balance calculations indicated only minor differences in the time course of plasma volume expansion between the conscious and anesthetized states. However, isoflurane anesthesia markedly reduced urinary volume (median, 9 vs. 863 ml; P < 0.03). In conscious sheep, the central and peripheral volume expansion predicted by volume kinetics agreed well with the calculations based on mass balance. However, during isoflurane anesthesia and mechanical ventilation, calculation using volume kinetic analysis of the variable kr, an elimination factor that, in conscious humans and sheep, is closely related to urinary excretion, represented both urinary excretion and peripheral accumulation of fluid. This suggests that the previous assumption that kr approximates urinary excretion of infused fluid requires modification, i.e., kr simply reflects net fluid movement out of plasma. CONCLUSIONS: In both conscious and anesthetized, mechanically ventilated sheep, infusion of 0.9% saline resulted in minimal expansion of plasma volume over a 3-h interval. In conscious sheep, infused 0.9% saline was rapidly eliminated from the plasma volume by urinary excretion; in contrast, the combination of isoflurane anesthesia and mechanical ventilation reduced urinary excretion and promoted peripheral accumulation of fluid.

Algorithms↗

Intraoperative motor-evoked potential monitoring in scoliosis surgery: comparison of desflurane/nitrous oxide with propofol total intravenous anesthetic regimens.

STUDY DESIGN: A prospective, randomized study in a large general hospital setting. BACKGROUND: During spinal surgery, monitoring motor-evoked potentials (MEPs) is a means of assessing the intraoperative integrity of corticospinal pathways. However, MEPs are known to be sensitive to the effects of anesthetic agents. OBJECTIVE: To compare the use of desflurane or total intravenous anesthetic regimens (TIVA) with multipulse cortical stimulation for intraoperative monitoring (IOM). METHODS: Twenty consecutive patients (10 in each arm) undergoing scoliosis correction surgery were randomly assigned to 2 equal groups receiving desflurane or TIVA. Inhalational anesthesia was maintained using 66% nitrous oxide in oxygen and a mean end-tidal desflurane concentration of 3.4%. For TIVA, continuous intravenous infusion of propofol was used. For analgesia, fentanyl and morphine were given when required for both groups. Cortical stimulation was achieved with 2 bipolar direct current stimulators connected in parallel by jumper cables. Five equivalent pulses 0.5 ms in duration at 4 ms intervals were delivered at C1C2 positions. MEP recordings were made in the abductor hallucis (AH) and tibialis anterior (TA) with needle electrodes. RESULTS: Reproducible MEPs were obtained throughout the operation in all 20 cases, with up to 80 mA per stimulator. Before insertion of pedicle screws, mean MEP amplitudes (SD) obtained were 85 (19) and 21.7 (10.8) mV for AH and TA, respectively, using desflurane. With TIVA, amplitudes were 56.7 (28.4) and 59.1 (24.5) mV, respectively. Both muscle MEP amplitudes were significantly different using different anesthetic regimens (P < 0.05 for all). AH MEP amplitudes obtained with desflurane were significantly larger than TA amplitudes (P < 0.0001). No complications were reported intraoperatively and postoperatively. CONCLUSIONS: This is the first study comparing the use of desflurane and TIVA showing that both anesthetic regimens allowed successful intraoperative monitoring useage throughout the procedures. For MEP recording, the AH was the preferred muscle with a desflurane anesthetic regimen.

Adolescent↗

Effects of halothane, enflurane, and isoflurane on supraventricular and ventricular rate in dogs with complete atrioventricular block.

Complete atrioventricular (AV) block was produced in 32 chloralose-anesthetized autonomically intact dogs to determine the effects of halothane, enflurane, and isoflurane on supraventricular and ventricular rate. Halothane (n = 17), enflurane (n = 6), and isoflurane (n = 9) were administered in three separate experiments in sequential minimum alveolar concentration (MAC) multiples of 0.5, 1.0, 1.5, 2.0, 1.5, and 1.0. Supraventricular rate, ventricular rate, and mean arterial blood pressure (MAP) were measured and recorded at baseline and after a 20-minute equilibration period of each inhalation anesthetic at each MAC multiple. Increasing concentrations of enflurane and isoflurane significantly decreased supraventricular rate (P < .05). Ventricular rate was not significantly changed by sequential MAC multiples of halothane, enflurane, and isoflurane. Increasing concentrations of halothane, enflurane, and isoflurane significantly decreased MAP with enflurane producing the most significant decrease (P < .05). Ventricular arrhythmias occurred in 5 of 17 dogs anesthetized with halothane and 1 of 9 dogs anesthetized with isoflurane. Inhalation anesthesia can significantly decrease supraventricular rate and MAP, does not alter ventricular rate, and can produce ventricular arrhythmias in dogs with complete AV block.

Anesthesia, Inhalation↗

Anesthetic and analgesic considerations in the experimental animal.

Many new compounds and combinations of many of the more traditional drugs have been used in a wide range of species. This, plus the rapid development in equipment for inhalational anesthesia, has simplified the restraint, anesthetic, post-surgical, and analgesic management of experimental animals.

Analgesia↗

Computerized continuous infusion of intravenous anesthetic drugs during pediatric cardiac surgery.

We evaluated the efficacy of a computer-assisted continuous infusion device (CACI) using a two-drug infusion of midazolam and sufentanil as an anesthetic technique during pediatric cardiac surgery. Seventeen pediatric patients were anesthetized with CACI using age-appropriate pharmacokinetic models for administering sufentanil and midazolam. Predicted CACI plasma concentrations were correlated with assayed plasma drug concentrations at eight predefined intervals. The accuracy was assessed using median absolute prediction error. We found that plasma levels predicted by CACI provided a reasonable approximation of measured plasma concentrations for both drugs. The median absolute prediction error for sufentanil during cardiopulmonary bypass was compared with measurements made off of cardiopulmonary bypass (both pre and post cardiopulmonary bypass) and were 49% and 32%, respectively, and for midazolam 44% and 32%, respectively. We conclude that (a) current kinetic models provide a reasonable estimate of plasma drug concentrations, and (b) the ease of administration and targeted plasma level provided by the CACI system is an alternative to inhalation anesthesia using calibrated vaporizers.

Adolescent↗

Anesthetic concerns for robot-assisted laparoscopy in an infant.

A 2-mo-old infant with biliary atresia was scheduled for laparoscopic Kasai with robot assistance. Before surgery, a practice trial maneuvering the cumbersome robotic equipment was performed to ensure rapid access to the patient in case of emergency. IV access, tracheal intubation, and arterial line placement followed inhaled anesthesia induction with sevoflurane. Robotic setup took 53 min and severely limited patient access. No adverse events occurred during the procedure requiring the removal of the robotic equipment, and the patient was discharged after a stable postoperative recovery. Advance preparation is required to maximize patient safety during robotic surgery.

Anesthesia, Inhalation↗

[Tracheal intubation under general anesthesia in patients with difficult laryngoscopy].

OBJECTIVE: To evaluate the safety and efficacy of oral endotracheal intubation in the patients with difficult laryngoscopy undergoing general anesthesia. METHODS: A total of 1 683 patients with difficult laryngoscopy, aged 1.5-67 yr, and scheduled for the elective plastic surgery were observed in this study from 1989-1997. All these patients were at American Society of Anesthesiologist physical status I. According to the preoperative predictive results for difficult laryngoscopy, we classified these patients into two groups: Group I included 1 375 patients, whose epiglottis could be viewed (laryngoscopic view grades II and III); and Group II, included 308 patients, whose epiglottis could not be viewed (laryngoscopic view grade IV). For group I, anesthesia was induced with thiopentone 4-5 mg/kg and succinylcholine 1 mg/kg; Laryngoscopy was carried out using modified Macintosh method. For Group II, anesthesia was induced with a total intravenous anesthesia or inhaled anesthesia; anesthetic depth was required to effectively inhibit laryngeal reflexes with reservation of spontaneous breathing. Tracheal intubation was performed by fiberoptic stylet laryngoscope (FOSL). During anesthesia induction and tracheal intubation procedures, electrocardiogram, arterial pressure, heart rate and pulse oxygen saturation (SpO2) were continuously monitored. Complications of intubation (arrhythmia, and so on) were observed and recorded. Immediately after laryngoscopy and successful intubation, patients were examined for any traumatic injuries at teeth, lips, tongue, and oropharyngeal tissues. RESULTS: In group I, tracheal intubation was accomplished by the first attempt in 1 279 cases (93.0%) and the intubation time was less than 3 min in 1 304 cases (94.8%). In group II, tracheal intubation was accomplished by the first attempt in 114 patients (37.0%), and 123 patients (39.9%) had the intubation time of less than 3 min. Tracheal intubation was successful by the second or third attempt in 96 patients of group I and 156 patients of group II, respectively. Thirty-eight patients required four or more attempts, which only occurred in group II. Of all the complications of tracheal intubation, the traumatic complications were most common. The incidences of traumatic complications in the patients with laryngoscopic view grade II, III (group I ) and IV (group II) were 0.7%, 3.9% and 14.3%, respectively. Other complications such as respiratory depression were only seen in group II. A pooled incidence of the intubation complications was 6.7% (113/1 683). CONCLUSION: An anesthesiologist who is skillful in difficult airway management may safely manage the airway in the patients with difficult laryngoscopy under general anesthesia.

Adolescent↗

[Study of xanthine oxidase activity in the brain tissue after administration of dalargin during myoplegia].

Effect of Dalargin (40 micrograms/kg) on xanthine-oxidase (X) activity in experimental Arduan-induced myoplegia (0.1 mg/kg) was studied in the brain tissue of 70 rats under inhalation anesthesia and artificial ventilation. Neither Dalargin nor Arduan was found separately to induce statistically significant changes in X activity. Dalargin injections in myoplegia caused significant (24.7%) reduction of the enzyme's activity.

Androstane-3,17-diol↗

A closed anesthetic system for small laboratory animals.

An anesthetic unit was developed that maintained adequate anesthetic levels, removed carbon dioxide, and contained gases. The device produced inhalation anesthesia in both small mammals and birds by using either halothane or methoxyflurane.

Anesthesia, Inhalation↗

Effect of low carrier gas flows (50% oxygen/50% nitrous oxide) on inspired oxygen tension in anesthetized dogs.

Low carrier gas flows of 50% oxygen/50% nitrous oxide were evaluated with regard to their effect on inspired oxygen (PIO2) and carbon dioxide (PICO2) tension during maintenance inhalational anesthesia in dogs, using a circle-system anesthetic machine. A total flow rate of 15 ml/min/kg was associated with a PIO2 of 230 +/- 25 mm of Hg and a PICO2 of 0.4 +/- 0.4 mm of Hg after 4 hours of methoxyflurane anesthesia. End-tidal carbon dioxide, minute volume ventilation, and ventilation frequency did not change during the 4 hours. Lower total flow rates were associated with collapse of the reservoir bag, or a PIO2 less than 200 mm of Hg, or both.

Anesthesia, Inhalation↗

[Induction of Anaesthesia in Children by Intramuscular Administration of Methohexital (author's transl)].

5 mg/kilogram bodyweight of a 5 per cent solution of methohexital was given intramuscularly, together with a vagolytic agent, to 102 children aged 5 months -- 9 years before inhalation anesthesia. Premedication was omitted. The technique resulted in smooth induction of sleep and rapid recovery with few side-effects. With certain precautions the technique is suitable for day-case surgery in children.

Anesthesia, Inhalation↗

[Anesthetic management of a patient with mild hypothyroidism].

A patient with mild hypothyroidism underwent a repair of abdominal aortic aneurysm. Although the serum TSH level of this patient was very high and T4, free T4 levels were low, T3 level remained within normal ranges. Inhalation anesthesia with continuous epidural block was selected and there was no complication such as hypotension or hypothermia during perioperative period. Recently, several reports demonstrate that the preoperative supplemental therapy of the thyroid hormone should not be necessary in the case of mild hypothyroidism. Moreover, the biological potency of T3 is higher than that of T4. Thus, in patients whose T3 level is kept within normal ranges even if serum T4 level is low and serum TSH level is high, we may say that they are in euthyroid state. We think these patients can be anesthetized safely.

Anesthesia, Epidural↗