Are preformed endotracheal tubes appropriately designed for pediatric patients?

BACKGROUND: The aim of the study was to examine different brands of preformed oral and nasal endotracheal tubes (ETT) and to assess whether the bend placement gave acceptable guidance for ETT depth positioning in children. METHODS: The distance from the vertex of the bend to the tip (bend-to-tip distance) of seven brands of preformed oral and nasal ETTs were measured. Front teeth-to-carina (FTC) and nares-to-carina (NC) distance data from orally (0-19 years) and nasally (0-8 years) intubated children were used to assess the risk of endobronchial intubation if a preformed ETT had been placed with its bend at the front teeth or nares. RESULTS: While the bend-to-tip distance of a cuffed oral preformed ETT only differed by 0-1 cm from a same size ETT from another brand, uncuffed oral ETTs differed by 0-4 cm. The bend-to-tip distance of cuffed and uncuffed ETTs of the same brand and size differed by 0-3 cm. Had preformed cuffed oral ETTs been placed with their bends at the front teeth in children of the FTC reference group, endobronchial intubation would have occurred in 0-27% of the patients, depending on the size and brand of the used ETT. In contrast to oral ETTs, the bend-to-tip distance of cuffed nasal ETTs differed more (0-5.5 cm) between brands, and uncuffed nasal ETTs less (0-3 cm). Also, the bend-to-tip distance of a cuffed nasal ETT was consistently greater (2-9 cm) than that of a same brand and size nasal uncuffed ETT. Had a preformed cuffed nasal ETT been placed with its bend at the nares in the NC reference group, 50-100% of the patients would have been endobronchially intubated. CONCLUSION: The bend-to-tip distance of preformed ETTs varies between brands, especially for nasal tubes. Some preformed tubes are not well suited for routine use in children. There is a high risk for accidental endobronchial intubation if a cuffed preformed ETT is positioned with its bend at the front teeth or nares in a young child. ETT tube tip position needs to be carefully controlled when a preformed ETT is used in a child.

Nares-to-carina distance in children: does a 'modified Morgan formula' give useful guidance during nasal intubation?

BACKGROUND: Knowledge of the normal nares-to-carina (NC) distance might prevent accidental bronchial intubation and be helpful when designing preformed endotracheal tubes (ETT). OBJECTIVE: The aim was to measure NC distance and to examine whether a height/length-based 'modified Morgan formula' would give useful guidance for nasotracheal ETT depth positioning. METHODS: Two groups were studied. A younger group consisted of nasally intubated postoperative patients. In these, NC distance was obtained as the sum of ETT length and the distance from the ETT tip to the carina, as measured from an anteroposterior chest X-ray. An older group consisted of children who had undergone computerized tomography (CT) examination including head, neck, and chest. In these, NC was measured directly from the CT image. The modified Morgan formula was derived from the NC vs height/length relationship. RESULTS: Nares-to-carina distance was best predicted by a linear equation based on patient height. The equation in the younger group (1 day-8 years, n = 57) was: NC (cm) = 0.14 × height + 5.8, R(2) = 0.90, and in the older group (2.1-20 years, n = 45): NC (cm) = 0.15 × height + 3.4, R(2) = 0.93. The equation for the groups combined (n = 102) was: NC (cm) = 0.14 × height + 6.2, R(2) = 0.97. Based on the latter equation, a modified Morgan formula was identified as: ETT position at nares in cm = 0.12 × height + 5. If the ETT had been placed as calculated by this formula, the ETT tip would have been at 85 + 5% (mean ± sd) of NC distance, and the ETT tip-to-carina distance would have been 3.1 ± 1.1 cm (range 0-6.6). Bronchial intubation would not have occurred in any child, but a comparison to tracheal length measurements indicates that ETT tip position could be too proximal in some children. CONCLUSION: The study confirms previous reports: NC distance can be well predicted from height/length. A modified Morgan formula might decrease the risk for accidental endobronchial intubation in infants and children, but ETT position need to be confirmed by auscultation or other verification.

Anesthesia in a 12 year old boy with somatic overgrowth secondary to pericentric inversion of chromosome 12.

The management of a splenectomy in a boy with an unusual form of somatic overgrowth is presented. Except for a moderately difficult airway, no unusual reactions to anesthesia and surgery were encountered. Possible anesthetic implications of different somatic overgrowth syndromes in children are presented.

Anesthesia for pheochromocytoma resection in a child with Fontan circulation.

PURPOSE: To report the anesthetic management of a successful resection of a pheochromocytoma in a child with a completed Fontan circulation. CLINICAL FEATURES: The patient was an 11-yr-old boy with Ivemark syndrome who had undergone Fontan palliation at three years of age. Six weeks earlier, he had been diagnosed with a norepinephrine-producing pheochromocytoma, and he had been pretreated with oral propranolol and phenoxybenzamine. During surgery, intravenous administration of magnesium sulphate, esmolol, and phentolamine provided good hemodynamic control. Postoperatively, the patient tended to be hypotensive, and treatment with fluid administration resulted in prolonged intensive care. CONCLUSION: Although intraoperative management was not problematic, postoperative care of this 11-yr old child with pheochromocytoma was complicated by residual sympathetic blockade.

Front teeth-to-carina distance in children undergoing cardiac catheterization.

BACKGROUND: Knowledge of normal front teeth-to-carina distance (FT-C) might prevent accidental bronchial intubation. The aim of the current study was to measure FT-C and to examine whether the Morgan formula for oral intubation depth, i.e., endotracheal tube (ETT) position at front teeth (cm) = 0.10 x height (cm) + 5, gives appropriate guidance when intubating children of different ages. METHODS: FT-C was measured in 170 infants and children, aged 1 day to 19 yr, undergoing cardiac catheterization. FT-C was obtained as the sum of the ETT length at the upper front teeth/dental ridge and the distance from the ETT tip to the carina. The latter measure was taken from an anterior-posterior chest x-ray. RESULTS: There was close linear correlation between FT-C and height: FT-C (cm) = 0.12 x height (cm) + 5.2, R = 0.98. The linear correlation coefficients (R) for FT-C versus weight and age were 0.78 and 0.91, respectively. If the Morgan formula had been used for intubation, the ETT tip would have been at 90 +/- 4% of FT-C. No patient would have been bronchially intubated, but the ETT tip would have been less than 0.5 cm from the carina in 13 infants. CONCLUSIONS: FT-C can be well predicted from the height/length of the child. The Morgan formula provides good guidance for intubation in children but can result in a distal ETT tip position in small infants. Careful auscultation is necessary to ensure correct tube position.

Total spinal in an infant: can 'dry taps' occur with 20G Tuohy needles?

The loss-of-resistance technique was used to place a 20G epidural needle in the lumbar region in an anesthetized and paralyzed infant. There was no cerebrospinal fluid (CSF) leakage and a 24G catheter was inserted through the needle. At end of surgery, when the patient was breathing spontaneously and a bupivacaine bolus was given through the catheter, a total spinal block was identified. A bench test demonstrated that CSF leakage from a 20G needle can be delayed if CSF pressure is low and if air bubbles are present in the needle.

Effect of polymer coating (poly 2-methoxyethylacrylate) of the oxygenator on hemostatic markers during cardiopulmonary bypass in children.

OBJECTIVE: Heparin and other oxygenator coatings have been used in attempts to reduce hemostatic activation during cardiopulmonary bypass (CPB). This study evaluated whether an oxygenator coated with poly 2-methoxyethylacrylate (PMEA) (X-coating; Terumo Corporation, Tokyo, Japan) would cause less activation of coagulation and fibrinolytic systems during CPB in children than a noncoated oxygenator. DESIGN: Observational study. SETTING: University-affiliated children's hospital. PATIENTS: Twenty-six patients, 3 months to 5 years old, who underwent congenital heart surgery for repair of a ventricular septal defect, atrial septal defect, or both. INTERVENTIONS: Patients were divided into 2 age-matched groups based on the type of oxygenator used: a noncoated oxygenator (group NC) versus a PMEA-coated oxygenator (group C). MEASUREMENTS AND MAIN RESULTS: Blood samples for coagulation and fibrinolytic markers were compared before, during, and after CPB. Despite increases in thrombin generation markers (F1.2 and TAT) at certain times during CPB in group C compared to group NC, a comparison over all times during CPB were not statistically different between groups. Overall D-dimer concentrations during CPB were elevated in group C compared to group NC (p = 0.02). Active tPA and active PAI-1 were not different between groups during or after CPB. Group C had higher platelet counts (181,000 +/- 29,000) during CPB than group NC (155,000 +/- 57,000, p = 0.04) but not postoperatively. Twelve hours postoperatively, chest tube outputs were 8.8 +/- 3 mL/kg in group C and 19.1 +/- 12 mL/kg in group NC (p = 0.003). The corresponding outputs 24 hours after surgery were 12.4 +/- 3 mL/kg and 24 +/- 11 mL/kg, respectively (p = 0.005). CONCLUSIONS: Except for a somewhat higher platelet count during CPB, there was no indication that PMEA coating resulted in less activation of coagulation and fibrinolytic systems. The lower postoperative chest tube output observed after CPB with PMEA-coated oxygenators needs to be studied further.

The hemodynamic and metabolic effects of shivering during acute normovolemic hemodilution.

UNLABELLED: To assess the hemodynamic and metabolic effects of shivering during extreme normovolemic hemodilution, we anesthetized 16 pigs with fentanyl-midazolam-pancuronium. Mild hypothermia (36.5 degrees +/- 0.1 degrees C) was induced by surface cooling, and the animals were randomized to either a control group (hemoglobin 118 +/- 3 g/L) or a hemodilution group (hemoglobin 52 +/- 2 g/L). In the latter group, blood was replaced with an isotonic Ringer's acetate/dextran 70 solution. Shivering was allowed to occur by a controlled decrease in the infusion rate of pancuronium. Shivering increased oxygen consumption (VO(2)) in both groups (P < 0.001). Initially, this was predominantly compensated for by an increased oxygen extraction ratio (ER), but when VO(2) was 2.3 +/- 0.2 times baseline, critical levels of mixed venous oxygenation (SVO(2) = 18% +/- 2%; PVO(2) = 22.5 +/- 1.5 mm Hg) and ER (82% +/- 3%) were recorded in anemic animals. Control animals did not reach critical levels until VO(2) was maximal (3.7 +/- 0.3 times baseline). Maximal attained VO(2) was less (2.9 +/- 0.1 times baseline) in the anemic animals (P = 0.01), and at this stage two of these pigs had myocardial lactate production, one of which died in ventricular fibrillation. Coronary perfusion pressure was significantly less (P < 0.001) in the anemic animals. We conclude that in this experimental model, maximal shivering as measured by VO(2) was limited in hemodiluted animals, and left ventricular oxygen balance was marginal, as evidenced by a decreased lactate uptake and extraction. IMPLICATIONS: The effect of acute increases in oxygen consumption (shivering) on severely anemic individuals has not been evaluated. In this experimental model, left ventricular oxygen balance was marginal, as evidenced by decreased lactate extraction.