G. W. Stevenson

Effects of adherence, activation and distinct serum proteins on the in vitro human monocyte maturation process.

Elutriator‐purified human monocytes were cultured in a serum‐free (SF) medium, and various serum proteins and functional activating agents were assessed for their effects on the in vitro maturation of human monocytes to macrophages. Following 3 days of suspension culture in Teflon labware, 60% of the monocytes were easily recovered. When varying concentrations of human AB serum (HuAB) were employed, human monocyte maturation progressed rapidly; the kinetics of this maturation process during cell suspension culture were very similar to the pattern observed following adherence culture. In contrast, when SF medium was employed, a marked retardation of the monocyte maturation process was observed; this could not be attributed to any changes in cell recovery and/or viability. Thus, cells could be maintained in their monocytoid form for 3 days when cultured in SF medium. When HuAB was added after 3 days of culture, human monocyte maturation into macrophages proceeded at a normal rate.

Comparison of a rigid laryngoscope with the ultrathin fibreoptic laryngoscope for tracheal intubation in infants

The flexible ultrathin fibreoptic laryngoscope allows placement of endotracheal tubes as small as 2.5 mm internal diameter. The purpose of this study was to document the safety and efficacy of intubation using an ultrathin fibreoptic laryngoscope. Proved safety and efficacy would justify the routine use of fibreoptic laryngoscopy in normal infants to maintain skills needed for management of the difficult infant airway. In this prospective study, 40 infants <24 mo of age scheduled for elective surgery were randomly divided into two equal groups. After inhalation induction of anaesthesia, in 20 infants the trachea was intubated using direct rigid laryngoscopy, and in 20 using the ultrathin fibreoptic laryngoscope (size 1.8 mm OD) Olympus LFP. Time to successful intubation was recorded, as well as blood pressure, heart rate, end-tidal CO2 and oxygen saturation. Airway trauma in the operating room, the post-anaesthesia care unit, and on the first postoperative day was recorded. The intubation times using rigid laryngoscopy were less than those using fibreoptic laryngoscopy (13.6 ± 0.9 sec (mean ± SEM) vs 22.8 ± 1.7 sec; P < 0.01). Oxygen saturation and end-tidal CO2 readings were not different between the two groups. After intubation, blood pressure and heart rate increased equally in both groups, returning to normal within one to two minutes. There was no difference in the airway trauma between groups. We conclude that the ultrathin fibreoptic laryngoscope is a safe and effective method for tracheal intubation in infants and may be used routinely in order to maintain fibreoptic airway skills.RésuméLe fibroscope ultrafin flexible à fibres optiques permet de placer des canules endotrachéales de diamètre interne aussi petit que 2,5 mm. Cette étude vise à démontrer la sécurité et l’efficacité de l’intubation avec un fibroscope ultrafin. La preuve de sa sécurité et de son efficacité justifierait son utilisation courante chez les enfants normaux pour maintenir la dextérité nécessaire à la prise en charge des cas difficiles. Pour cette étude prospective, 40 enfants de 24 mois ou moins programmés pour une chirurgie réglée sont répartis au hasard en deux groupes égaux. Après une induction par inhalation, chez 20 enfants, la trachée est intubée par laryngoscopie rigide directe, et chez un même nombre, avec le fibroscope ultrafin (diamètre externe 1,8 mm) Olympus LFP. Le délai jusqu’à la réussite de l’intubation est enregistré, ainsi que la pression artérielle, la fréquence cardiaque, la CO2 télé-expiratoire et la saturation en oxygène. Tout traumatisme aux voies aériennes en salle d’opération, salle de réveil et au premier jour après l’opération est aussi noté. Le temps requis pour l’intubation avec le laryngoscope rigide est moindre qu’avec le fibroscope (13,6 ± 0.9 sec (moyenne ± SEM) vs 22,8 ± 1,7 sec; P < 0,01). La saturation en oxygène et le CO2 télé-expiratoire ne diffèrent pas entre les deux groupes. Après l’intubation, la pression artérielle et la fréquence cardiaque augmentent également dans les deux groupes et retournent à la normale en deçà d’une ou deux minutes. Pour les tramatismes, il n’y a pas de différence entre les deux groupes. En conclusion, on peut utiliser le fibroscope avec efficacité et sécurité pour l’intubation des enfants et de façon courante pour maintenir son habileté avec ce type d’instrument.

Sodium nitroprusside metabolism in children during hypothermic cardiopulmonary bypass.

Ten children, aged 1-7 yr, presenting for repair of complex congenital heart lesions, were prospectively studied. A ketamine, halothane/isoflurane, and fentanyl anesthetic was used. After initiation of hypothermic cardiopulmonary bypass, sodium nitroprusside (SNP) was titrated as necessary to maintain a target mean arterial blood pressure of 35-60 mm Hg. Blood samples drawn immediately prior to starting SNP infusion, every 15 min during infusion, and at 1, 4, and 24 h postinfusion were analyzed for whole blood cyanide (CN sub.-) and serum thiocyanate (SCN-). Blood gas analysis was performed every 30 min during SNP infusion. A maximum CN- level >or=to1.0 micro gram/mL was observed in two children; four others had maximum CN- levels between 0.5 micro gram/mL and 1.0 micro gram/mL (normal, <0.2 micro gram/mL). No child had a clinically important increase of SCN- subsequent to SNP infusion. There was substantial variability in observed CN- accumulation during SNP infusion. CN- levels during the first 60 min correlated with the average SNP rate of administration (P = 0.02). Cyanide levels rapidly decreased after termination of SNP infusion and were undetectable 4 h postinfusion. Despite the short-term increase of CN- level, no child showed biochemical signs of toxicity (acidosis or increased mixed venous oxygen tension). (Anesth Analg 1995;81:952-6)

A comparison of three modes of ventilation with the use of an adult circle system in an infant lung model

We examined the efficiency of an adult circle system with adult bellows to deliver minute ventilation (VE) to an infant test lung model.A Narkomed 2B system (North American Drager, Telford, PA) using three modes of ventilator setup were used: A = time-cycled, volume-controlled using bellows excursion to control delivered volume; B = time-cycled, pressure-controlled using inspiratory pressure limit adjustment to control delivered volume; C = time-cycled, pressure-controlled using the inspiratory flow adjustment to control delivered volume. VE was measured with two compliances (normal and low) and four endotracheal tube (ETT) sizes (2.5-, 3.0-, 3.5-, and 4.0-mm inner diameter). VE was measured at peak inspiratory pressures (PIP) of 20, 30, 40 or 50 cm H2 O while respiratory rate (RR) was held constant at 20 breaths/min. VE was measured as RR was set at 20, 30, 40, or 50 breaths/min while target PIP was held constant at 20 cm H2 O. Data were analyzed using the multiple regression technique. With the low compliance model, VE was nearly identical regardless of the ventilator setup. With the normal compliance model, minor differences in VE were observed, especially at the highest RR and PIP. VE was dependent on RR, PIP, and lung compliance. Overall, the ventilator setup resulted in minor changes in VE. Very high PIPs were required to deliver VE to the low compliance model. ETT size did not affect VE when lung compliance was low; however, smaller ETT size was a factor when test lung compliance was normal, decreasing delivered VE at higher PIP and RR. We conclude that with a Narkomed 2B adult circle system VE is dependent on PIP, RR, and lung compliance, but not on mode of ventilator setup. Implications: The results of this laboratory investigation indicate that when an adult circle system is used during infant anesthesia, the ventilation delivered depends primarily on the respiratory rate, peak inspiratory pressure, and the compliance of the lung being ventilated, rather than on the specific mode of ventilator setup. (Anesth Analg 1998;87:766-71)

Rigid endotracheal tube stabilization during craniomaxillofacial surgery.

Effective stabilization of the endotracheal tube is required for safety when performing surgery in the craniomaxillofacial region. We describe a simple technique for rigid stabilization of the airway, which has been used in over 150 patients without complication.

Pressure-limited ventilation of infants with low-compliance lungs: the efficacy of an adult circle system versus two free-standing intensive care unit ventilator systems using an in vitro model.

UNLABELLED We compared the efficacy of a Drager Narkomed GS (North American Drager, Telford, PA) equipped with an adult circle system with two free-standing infant ventilator systems (Servo 300; Siemens Medical Systems, Danvers, MA and Babylog 8000; North American Drager) to deliver minute ventilation (VE) using pressure-limited ventilation to a test lung set to low compliance. To simulate a wide variety of potential patterns of ventilation, VE was measured at peak inspiratory pressures (PIP) of 20, 30, 40, and 50 cm H2O and at respiratory rates (RR) of 20, 30, 40, and 50 breaths/min. Each measurement was made three times; the average was used for data analysis using the multiple regression technique. Delivered V(E) was positively correlated with both PIP (P = 0.001) and RR (P = 0.001). Only minimal differences in VE were observed between the circle and the two free-standing systems. At lower RR and PIP, the Babylog 8000 system delivered slightly higher VE than the circle system, whereas at higher RR and PIP, the Babylog 8000 delivered slightly lower VE than the circle system; these differences in VE were not statistically significant (P = 0.45). The Servo 300 delivered slightly higher VE than the circle system in all test conditions, but these differences were not statistically significant (P = 0.09). None of the differences in delivered VE between the Servo 300 and the circle system are of clinical importance. IMPLICATIONS Our laboratory investigation suggests that pressure-limited ventilation delivered by a standard adult circle system compares favorably with that of freestanding infant ventilators used in pressure-limited mode. Changing from an adult circle system to a free-standing pressure-limited ventilator may not substantially improve ventilation of a low-compliance infant lung; the efficacy of such a practice should be investigated.

Anesthetic management of children with intracardiac extension of abdominal tumors

ome abdominal tumors have a marked propensity for intraluminal venous extension. NephroS blastoma (Wilms’ tumor) is the second most common solid abdominal tumor of childhood and presents with renal vein and inferior vena cava (IVC) invasion in approximately 10% of cases (11, though extension into the heart is rare. We describe two cases of intracardiac extension of a nephroblastoma and a case of intracardiac extension of a hepatic neuroendocrine tumor. These tumors presented several anesthetic and surgical challenges and were resected with the use of cardiopulmonary bypass (CPB).

Use of the Olympus LF‐P fibreoptic laryngoscope by trainees in paediatric anaesthesia

patients scored their pain greater than 50 on a l00mm visual analogue scale (VAS) and that the majority of morphine consumption took place in the first 18 h. The authors express concern that analgesia for some patients treated on a day-stay basis may therefore be suboptimal. They list five studies of the use of non-steroidal anti-inflammatory drugs (NSAIDS) and one study of tramadol for pain relief after dental surgery, but make no reference to the use of adjuvant local anaesthesia to enhance the quality of postoperative analgesia. Previous workers [ I , 21 have identified the analgesic benefits of adjuvant local anaesthesia for third molar extraction under general anaesthesia. With use of plain bupivacaine 0.25%, the proportion of patients with pain scores at 5 h greater than 25 on a 100 mm VAS decreased from 52% to 14% [ I ] . No unpleasant numbness with plain bupivacaine 0.5% was reported [2], opioid requirement decreasing from 62% to 26% and the proportion requiring no additional analgesia increased from 18% to 30%. Bupivacaine 0.75% plus adrenaline 1 :200 000 was compared with lignocaine 2% plus adrenaline 1:80000 for extraction under local anaesthesia [3]. Use of bupivacaine increased the mean pain-free period from 3 to 6 h and the proportion requiring no additional analgesia from 21 YO to 59%. In overlooking the role of adjuvant local anaesthesia for postoperative analgesia, Tighe er a/. appear to confirm the findings from our survey of the membership of the Association of Dental Anaesthetists (response rate 72%) in which a dichotomy in current UK practice was identified. The anaesthetists were asked if their surgeon ever used local anaesthesia as an adjuvant to general anaesthesia. The largest group (45%) replied that they have never used i t yet gave no reason for non-use. A further 12% never used adjuvant local anaesthesia. but gave a number of clinical reasons for non-use. However, 36% used i t routinely and 54% of this group do so in every case (18% of all those responding). The most popular agent (60% of users) was 2% lignocaine with adrenaline 1 : 80 000 via a dental syringe (non-aspirating) and dental needle. Bupivacaine 0.25-0.5% with adrenaline 1:200000 was used by 15%, using a disposable syringe and conventional needle. Although vasoconstrictor was not specified on only 4% of occasions, analgesia was cited as the prime reason for use by 75% of responders. Two-thirds chose to administer local anaesthetic by simple local infiltration, one-third by formal dental nerve block (10% performed inferior dental block for the lower teeth and simple infiltration for the upper teeth). It would therefore appear that, despite published work describing the effectiveness and safety of adjuvant local anaesthesia for postoperative analgesia following extraction of wisdom teeth under general anaesthesia [ 1-31, almost half the oral surgeons in the UK d o not appear to have considered making use of this means of pain relief, whereas 18% use it in all cases. Simple local infiltration of local anaesthetic plus vasoconstrictor avoids the risks of dental nerve block, improves definition of tissue planes, renders the surgery less bloody and also reduces the requirement of maintenance anaesthetic agents promoting prompt comfortable recovery from anaesthesia. The quality of postoperative symptom control is thus enhanced. The findings of this survey were presented at the Summer Meeting of the Association of Dental Anaesthetists in 1994.

Anaesthetic anagement of Miller’s syndrome

Miller’s syndrome is a rare congenital disorder with facial features similar to that of Treacher-Collins syndrome. This report details the anaesthetic management of an infant during multiple surgical procedures, beginning with pylormyotomy at one month of age. Airway management was difficult because of severe micrognathia and was accomplished using an awake intubation with a conventional straight blade modified for continuous administration of oxygen (“oxyscope”). Due to recurrent upper airway obstuction and the anticipated need for multiple surgical procedures in the first years of life, a tracheostomy was placed. Because of the multiple airway, orthopaedic, and nutritional difficulties, it is important that a prospective, multidisciplinary approach be used in these patients’ care. Consideration should be given to early tracheostomy for airway maintenance.RésuméLe syndrome de Miller est une maladie congénitale rare avec des caractéristiques faciales similaires au syndrome de Treacher-Collins. Ce rapport étudie la conduite anesthésique chez un enfant lors de procédures chirurgicales multiples, commençant par une pyloromyotomie à l’àge d’un mois. Le contrôle des voies aériennes fut difficile à cause d’une micrognatie et fut accompli par une intubation réveillée avec une lame droite conventionnelle modifiée pour l’administration continue d’oxygène (« oxyscope »). A cause de problèmes d’obstruction des voies aériennes hautes récurrentes et l’anticipation d’une nécessité de procédures chirurgicales multiples dans les premières années de la vie, une trachéotomie fut faite. A cause de problèmes multiples des voies aériennes, orthopédique et nutritionnelles, it est important d’instaurer une approche multidisciplinaire pour le soin de ces patients. Des considérations doivent être faites pour une trachéotomie précoce pour le maintien des voies aériennes.