The use of the Beck Airway Airflow Monitor for verifying intratracheal endotracheal tube placement in patients in the pediatric emergency department and intensive care unit.

Traditional methods of confirming that the endotracheal tube is in the trachea are often unavailable or difficult to perform in some clinical situations, such as interfacility transport or other times outside the neonatal intensive care unit. We evaluated the Beck Airway Airflow Monitor (BAAM), through which airflow makes a whistling sound, for its safety and efficacy in neonates. We studied 46 neonates ranging in weight from 0.6 to 3.7 kg. We found that the BAAM consistently produced the desired whistling sound signaling intratracheal placement of the endotracheal tube in all infants weighing above 1.5 kg. No adverse effects or complications were noted. The results support the safety and efficacy of the BAAM in confirming intratracheal endotracheal tube position in neonates.

Antisense oligodeoxynucleotide: inhibitor of splicing of mRNA of human immunodeficiency virus.

Antisense oligodeoxynucleotide (ODN), which are directed against the splice acceptor site of exon II of the regulatory gene tat of the human immunodeficiency virus type 1 (HIV-1), have been described. These 20-mer ODN's displayed moderate anti-HIV activity in vitro. Using the same antisense ODN (termed ODN-2), which was additionally modified and protected both at the 3'- and the 5'-terminus by two phosphorothioate internucleotide linkages, a strong anti-HIV activity (EC50: 2.7 micrograms/ml) could be measured in the HIV-1/CEM- and HIV-1/HeLa-T4+ cell system. The analogous ODNs which were protected only at one end were either inactive (up to 10 micrograms/ml) or displayed a low antiviral activity. Time kinetic studies revealed that the antisense ODN-2 reduced the release of HIV-1 already after an incubation time of 1 h. By applying S1 nuclease protection procedures, it could be established that the antisense ODN-2 inhibited splicing of high molecular weight transcript to the 2-kb tat mRNA in HIV-1-infected CEM cells. Transfection experiments with pU3R-III chloramphenicol acetyltransferase expression vector in HeLa-T4+ cells revealed that the antisense ODN-2 blocked the Tat protein-mediated transactivation process. In co-transfection experiments using pSV2tat72 or scrape loading studies with purified Tat, the transactivation was restored. These data indicate that the selected antisense ODN-2 displays its anti-HIV effect by blocking the splicing process leading to the functional 2-kb tat mRNA.

Stridor: intracranial pathology causing postextubation vocal cord paralysis.

During an 18-month period in a pediatric intensive care unit, nine patients with vocal cord paralysis were identified using flexible bronchoscopy. When tracheally extubated, each child was found to have stridor. The children ranged in age from 17 days to 5 1/2 years. Two patients had unilateral paralysis, but neither required tracheostomy. Seven patients displayed bilateral abductor vocal cord paralysis. Of these, six patients required tracheostomy. Surgical injury to the recurrent laryngeal nerve was the probable cause in two patients. The other seven patients had neurologic disorders with documented or suspected increases of intracranial pressure. Four of the seven patients with bilateral abductor vocal cord paralysis regained cord mobility within 4 months. Both children with unilateral cord paralysis have no stridor and vocalize well 1 year later. Cord paralysis in the setting of intracranial hypertension probably results from compression or ischemia of the vagus nerve before it exits the skull. Early visualization of the larynx should be done in patients who become stridulous when extubated, especially those with prior thoracic procedures or with neurologic disorders associated with intracranial hypertension.

Dependence of oxygen consumption on oxygen delivery in children with hyperdynamic septic shock and low oxygen extraction.

We studied the effect of increasing systemic oxygen delivery (DO2) by packed RBC (PRBC) transfusion on oxygen consumption (VO2) in children with hyperdynamic septic shock. After routine resuscitation with volume loading and pharmacologic support, patients were studied if they had significant derangements of oxygen transport variables defined as: baseline VO2 less than 180 ml/min.m2 and oxygen extraction (O2 extr) less than 24%. Eight studies were performed. PRBC transfusion increased DO2 from 636 +/- 167 to 828 +/- 266 ml/min.m2 (p less than .01) without increasing cardiac index (5.2 +/- 1.3 vs. 5.0 +/- 1.4 L/min.m2). VO2 increased from 112 +/- 36 to 157 +/- 60 ml/min.m2 (p less than .01) while O2 extr was unchanged (18 +/- 3% vs. 19 +/- 6%). Despite initial low O2 extr, VO2 can be increased in pediatric septic shock by a further increase in DO2. Since VO2 correlates with survival, one should consider enhancing DO2 further despite initial low O2 extr and high DO2. Effects on morbidity and mortality require further study.

Trending of impedance-monitored cardiac variables: method and statistical power analysis of 100 control studies in a pediatric intensive care unit.

The NCCOM3-R6 monitor continuously monitors cardiac output and five other cardiovascular variables from the thoracic electrical bioimpedance signal. We averaged data over 5-min intervals for 130 min in 100 control studies in 40 pediatric ICU patients, age 0.04 to 20.39 yr (median 1.39) and weighing 2.0 to 59.5 kg (median 8.8). For individual studies, 99% of the 5-min averages of cardiac output fell within +/- 44% of the baseline cardiac output for that study. Normal ranges were somewhat narrower for the other five variables. When we averaged data for 100 studies, 5-min interval observations for each variable did not deviate from baseline over a 2-h period (p greater than .70). With a sample size of 100 studies, we could detect a change in cardiac output of +/- 5% at the p less than .005 level with a power of 0.95. We conclude that with a sufficiently large sample size, studies employing the NCCOM3 can detect clinically significant cardiovascular changes due to pharmacologic or procedural stressors.

Percutaneous catheterization of the axillary vein in infants and children.

The axillary vein was evaluated as an alternative access site for central venous catheterization in critically ill infants and children. Children were placed in the Trendelenberg position (when possible) with arm abducted 100 to 130 degrees. The vein was entered parallel and inferior to the artery. Success rate for catheterization was 79% (41/52). Catheter diameter range was 3 to 8.5 F and catheter length range was 5 to 30.5 cm. Median patient weight was 7.0 kg (3.0 to 59 kg). Median age was 0.91 years (14 days to 9 years). All central lines ended in the subclavian, innominate, or superior vena cava. Median catheter duration was 8 days (2 to 22 days). A total of 338 patient catheter-days were studied. Central venous pressure was successfully monitored in five of five attempts. Complications with insertion (3.8% of attempts) included one pneumothorax and one hematoma. Complications during catheter duration (9.8% of catheters, 1.1% per catheter-day) included one instance each of venous stasis, venous thrombosis, catheter sepsis, and parenteral nutrition infiltration. No complication contributed to a patient mortality. Success and complication rates were comparable with those in jugular catheterization studies in children. The axillary approach is an acceptable route for central venous catheterization in critically ill infants and children.

Age-related differences in the use of morphine, diazepam, and pancuronium for mechanically ventilated children.

Mechanically ventilated children usually require a combination of sedation (morphine = M, diazepam = D) and paralysis (pancuronium = P) to minimize anxiety, discomfort, and the risks of self-extubation, tracheal injury, and pulmonary barotrauma. We sought to determine whether our use of MDP varied with patient age. Cases where the dosage of MDP would be influenced by neurological, hemodynamic, or painful diagnoses were excluded. The 36 cases selected were divided according to age into three groups (less than 4 months = A, 4-18 months = B, greater than 18 months = C). The daily sum of MDP dosages was calculated for each of the 326 study days, a mean of 9 study days for each case. The median daily drug usage in group B (2.3 mg/kg/day) was twice that in either group A (younger) or group C (older) (both p less than 0.001). This finding may be explained by developmental changes in physiology, pharmacology, and behavior, and may have been influenced by a paradoxical drug effect or multiple drug antagonism.

Organ blood flow and cardiovascular effects of high-frequency oscillation versus conventional ventilation in dogs with right heart failure.

Mongrel dogs underwent a large (apex to pulmonary valve) right ventriculotomy to produce right ventricular dysfunction. Right ventriculotomy decreased cardiac output from 2.47 +/- 0.43 to 1.34 +/- 0.16 L/min (p less than .01), increased CVP from 3.7 +/- 1.5 to 8.3 +/- 2.4 mm Hg (p less than .01), and decreased mean systemic arterial pressure (MAP) from 143 +/- 16 to 121 +/- 21 mm Hg (p less than .01). There was no effect on mean pulmonary artery pressure (MPAP) or pulmonary artery occlusion pressure. After stabilization a randomized crossover controlled comparison of conventional mechanical ventilation (CMV) and high-frequency oscillation (HFO) was performed. FIO2, pH, PCO2, core temperature, and preload were held constant. Mean airway pressure (Paw) was 4.8 +/- 0.7 cm H2O on CMV vs. 3.5 +/- 1.0 cm H2O on HFO (p less than .05). There was no difference in PaO2. We found no statistically significant differences between the two modes of ventilation with respect to cardiac output, MAP, MPAP, systemic vascular resistance, and pulmonary vascular resistance. Blood flows to cerebral cortex, renal cortex, adrenal, hepatic artery, left ventricular myocardium, and skeletal muscle were not different when comparing CMV to HFO. Despite the ability to attain equivalent oxygenation and ventilation at lower Paw, HFO offers no hemodynamic advantage over CMV in the presence of right ventricular dysfunction.

High-frequency ventilation versus conventional ventilation in dogs with right ventricular dysfunction.

A randomized crossover protocol was used to compare conventional mechanical ventilation (CMV) and high-frequency ventilation (HFV) in mongrel dogs experiencing right ventricular dysfunction after right ventriculotomy. When inspired oxygen, pH, PCO2, core temperature, and preload were held constant, cardiac output increased significantly (p less than .05) from 1.16 +/- 0.24 to 1.38 +/- 0.25 L/min and pulmonary vascular resistance decreased significantly (p less than .05) from 734 +/- 257 to 554 +/- 169 dyne X sec/cm5 during HFV relative to CMV. We also noted a significant (p less than .05) increase in mean arterial pressure from 116 +/- 27 to 124 +/- 23 mm Hg and a significant (p less than .05) increase in left ventricular stroke work from 10.2 +/- 3.5 to 12.3 +/- 2.6 g X m during HFV. During the inspiratory phase of CMV there were increases in CVP, pulmonary artery pressure, and systemic arterial pressure, and decreases in pulmonary artery flow which did not occur during HFV. HFV may be preferable to CMV in the presence of right ventricular dysfunction.

Shock following generalized hypoxic-ischemic injury in previously healthy infants and children.

Eighteen previously healthy patients with hypoxic-ischemic shock were observed longitudinally by means of data measured or derived from systemic arterial and pulmonary artery catheters. Shock was characterized by low cardiac index, elevated right and left heart filling pressures, elevated systemic and pulmonary vascular resistances, decreased oxygen consumption, and elevated oxygen extraction indices. Oxygen consumption was significantly correlated with oxygen delivery (r = 0.74, P less than 0.0001). This pattern fits that of cardiogenic shock. Cardiopulmonary data were not significantly different in survivors (n = 10) and nonsurvivors (n = 8). Outcome was determined by neurologic injury.