Babu V. Koka

Postintubation croup in children.

Incidence of and contributory factors in postintubation laryngeal edema were determined in 7875 children under 17 years of age. Data were assembled in the manner of a prospective study. With an overall incidence of 1 percent, children between ages 1 and 4 were most susceptible. Excessive size of the endotracheal tube was suspect in half of the cases. Other factors that increase trauma to the larynx while an endotracheal tube is in place showed significant correlation to the total incidence of postintubation laryngeal edema. No tracheostomies were required.

Effects of halothane on children's electroretinograms.

BACKGROUND At times, anesthesia is necessary to test childrens electroretinographic (ERG) responses. Halothane, an anesthetic commonly used for pediatric patients, affects some aspects of ERG responses, but it is unknown if halothane affects ERG parameters evaluated by contemporary clinical protocols. METHODS Scotopic and photopic ERG responses were recorded from children when awake and then under halothane. RESULTS Halothane has no effect on scotopic b-wave stimulus/response parameters, including amplitude, sensitivity, and implicit time. Scotopic a-wave amplitudes, implicit times, model parameters, and ratio of a- to b-wave amplitudes are unaffected by halothane. The amplitudes and implicit times of photopic responses to red flashes and 30 Hz flickering white light are not altered by halothane. Halothane causes no significant change in amplitudes and implicit times of the oscillatory potential wavelets. CONCLUSION These results suggest that significant departures of ERG responses (studied with the protocol described herein) from a laboratorys normal values cannot be attributed to halothane.

Lung growth after reduced size transplantation in a sheep model.

BACKGROUND The growth of mature allografts is a critical issue in pediatric lung transplantation. This study explores the architectural changes of mature sheep lung when submitted to two different compensatory growth forces: either transplantation into a neonatal host or expansion in an otherwise empty adult hemithorax. METHODS Right upper lobes (RUL) (mean+/-SEM, 66.7+/-1.9 kg) from 4- to 5-year old (adult sheep) were transplanted into newborn (n=6) lambs (5.4+/-0.3 kg, 5+/-2 days old) that were then allowed to survive for 45 days. Changes in pulmonary volume and architecture were measured before and after transplantation. Allografts were compared with both normal adult RUL (n=10) and adult (65.8+/-2.2 kg and 4 to 5 year old) RUL that remained in situ for 45 days after resection of the corresponding middle and lower lobes (n=6). Statistical differences were analyzed using two-sample and paired t tests. RESULTS In adult animals, RUL remaining in the otherwise empty hemithorax compensated by an 85% increase in volume (251.5+/-18.7 ml vs. 466+/-32.8 ml) (P<0.0001). Concomitant increases in total internal alveolar surface area (48%) and alveolar size were prominent. The number of alveoli per volume decreased proportionately to the increases in volume (P<0.0001). There was no significant change in the calculated number of alveoli (345.6+/-40.5 x 10(6)) compared with the normal adult RUL (402.4+/-40.7x10(6)) (P=0.37). Transplant recipients received a reduced-size normal adult RUL (49%) in volume (125.3+/-21.5 ml). Allografts 45 days after transplantation showed a 73% increase in volume (216.4+/-21.3 ml) (P<0.0001) with a parallel (83%) increase in total internal alveolar surface area (P=0.008). The number of alveoli per volume remained constant (P=0.21) despite the increase in volume. There was therefore a significant increase in the calculated number of alveoli from before transplantation (172.5+/-35.9x 106) compared with that observed 45 days after transplantation (389.7+/-77.7x10(6)) (P=0.012). CONCLUSIONS We conclude that mature sheep RUL parenchyma compensates with dilation of the respiratory structures in the adult animal, whereas there is alveolar multiplication when transplanted into newborn recipients.

Size disparity in pediatric lung transplantation

Donor scarcity and the limitations of organ preservation dictate that a wide size range be used to maximize effective donor utilization in pulmonary transplantation. Problems of size disparity are magnified in the pediatric population, where relevant dimensions vary considerably by age. There have been 10 pediatric lung recipients (7 bilateral, 2 single, 1 heart-lung) at our institution since 1991. The age range was 3 to 26 years (mean, 13.7), and the weight range was 15 to 57 kg (mean, 33.6). Diagnoses included cystic fibrosis (5), pulmonary fibrosis (2), pulmonary hypertension (2), and arteriovenous malformation (1). The donor-to-recipient weight ratio ranged from 0.45 to 1.9, and the donor-to-recipient thoracic height ratio ranged from 0.6 to 1.6. Lobar resection and delayed chest closure was required in one case and was successful. Cardiopulmonary bypass was used electively in seven cases. No reexplorations for bleeding were necessary. Two of the three hospital deaths resulted from right ventricular failure, judged to be secondary to excessive pulmonary artery pressures intraoperatively associated with small donor allografts. Elective bypass had not been used. Inhaled nitric oxide (6 patients) and/or extracorporeal membrane oxygenation (2 patients) were used for temporary postoperative support. The hospital survival rate was 70% (7/10). One late death occurred 14 months postoperatively and was caused by obliterative bronchiolitis. The authors conclude that size disparity is a significant problem in pediatric lung transplantation. However, with elective use of cardiopulmonary bypass and aggressive postoperative support, a broad size range can be used.

Perioperative considerations in a hypothyroid infant with hepatic haemangioma

Hepatic haemangiomas in infants are rare. An infant with both a hepatic haemangioma and a severe hypothyroid condition, unresponsive to conventional thyroxine therapy, will be described. This case presented here is the perioperative management of a critically ill infant who had myocardial depression secondary to hypothyroidism and a hepatic haemangioma that required embolization. To our knowledge, this is the first published report describing intravenous triiodothyronine as a therapeutic modality to stabilize a hypothyroid infant prior to undergoing a general anaesthetic.

ANESTHESIA FOR PEDIATRIC RADIOLOGY

With an expanding field of radiologic procedures and interventions, the pediatric anesthesiologist is being frequently called on to provide anesthetic coverage for children undergoing both invasive and noninvasive radiologic studies. Anesthetic involvement is frequently necessary in order to complete these pediatric radiologic procedures. The anesthesiologist can provide an invaluable service to the radiologists. The children in need of anesthesia can present both medical and anesthetic challenges. Providing anesthesia in the radiologic suites requires not only a familiarity with the procedures, but also careful and extensive planning and resources.

Tissue Uptake and Excretion of Nitrous Oxide in Pediatric Anesthesia

Tissue uptake and excretion of nitrous oxide (N2O) were determined in six dogs and seven patients, using a medical mass spectrometer with Teflon® sampling probes. For the measurements, NO+ fragment, which is proportional to the total amount of N2O was used. The Teflon sampling catheters were placed in the rectus femoris muscle in both groups and in the abdominal aorta of the dogs.Skeletal muscle N2O tensions (PN2O) were measured during general anesthesia with 70 percent N2O. In dogs, 95 percent of arterial uptake occurred in 18 (±11.58) minutes, and 95 percent arterial excretion took 19.5 (±5.22) minutes. Skeletal muscle took 75 (±35.89) minutes for 95 percent uptake. Excretion of skeletal muscle took 106.5 (±29.21) minutes. Uptake and excretion curves of patients are presented in the form of individual graphs.

CHAPTER 46 – Anesthesia Outside the Operating Room

The text also covers surgical procedures and anesthetic considerations by procedure location, such as radiology, infertility clinics, field and military environments, and pediatric settings, among many others Select guidelines from the American Society of Anesthesiologists (ASA) are provided as well. Edited by the senior faculty from Harvard Medical School and with contributions from other academic institutions, Anesthesia Outside of the Operating Room provides a unique and convenient compendium of expertise and experience.