Timothy C. Frewen

Cerebral blood flow, cross-brain oxygen extraction, and fontanelle pressure after hypoxic-ischemic injury in newborn infants

The relationship between mean arterial pressure, intracranial pressure, cerebral blood flow, cross-brain oxygen extraction, cerebral metabolic rate, and outcome was studied during therapy in nine neonates on 3 consecutive days after severe hypoxic-ischemic cerebral injury. Cross-brain oxygen extraction was significantly higher (5.06 +/- 0.5 vs 2.05 +/- 0.8 ml/dl; p = 0.012) in the five neonates who survived with normal neurologic outcome than in the four who died or sustained severe brain damage. In contrast, global cerebral blood flow in the five neonates with normal neurologic outcome was significantly lower (25.6 +/- 8.2 vs 83.2 +/- 44.9 ml/100 gm brain/min; p less than 0.05) during the study period. The differences in cross-brain oxygen extraction and global cerebral blood flow between infants who had neurologic recovery and those who died or sustained brain damage occurred in the presence of acceptable values for intracranial pressure, mean arterial pressure, and cerebral perfusion pressure. Our preliminary data suggest that cross-brain oxygen extraction and possibly global cerebral blood flow may be important variables associated with severe neuronal injury and death after hypoxic-ischemic cerebral injury.

The child requiring transport: lessons and implications for the pediatric emergency physician.

A retrospective review of the charts of all patients transported by our emergency transport team was done to determine the following characteristics: age, presenting problem, and outcome of patients and utilization of transport team personnel. Eighty-five percent of patients were under six years of age; central nervous system pathology accounted for 53% of patients transported, followed by respiratory problems (30%), cardiac problems (4.2%), and major trauma (2.7%). Sixty patients survived with normal neurologic examination at discharge. A statistically significant difference in retrospectively assigned PSI score (17.0 ± 6.02 in nonsurvivors versus 5.8 ± 6.02 in survivors) was observed. Utilization of the transport team was deemed appropriate. Comparison of our data with other available sources, as well as suggestions for emergency physicians and continuing medical education programs, is outlined.

Relationship of cross-brain oxygen content difference, cerebral blood flow, and metabolic rate to neurologic outcome after near-drowning

We evaluated the relationship of global cerebral blood flow, cross-brain oxygen content difference, cerebral metabolic rate for oxygen, intracranial pressure, and cerebral perfusion pressure to functional neurologic outcome in 12 comatose children on 2 consecutive days after near-drowning. Five children survived with functional neurologic outcome; five died and two survived with severe neurologic damage. Children who survived with functional neurologic outcome had a significantly higher cross-brain oxygen content difference (7.89 +/- 2.62 vs 3.91 +/- 1.59 ml/dl; p = 0.028) at 24 hours and a higher cerebral metabolic rate for oxygen 48 hours after admission (3.19 +/- 2.86 vs 0.96 +/- 0.45 ml/100 gm per minute; p = 0.030) compared with those who died or survived in a damaged state. There were no significant differences in global cerebral blood flow, intracranial pressure, and cerebral perfusion pressure between groups at either 24 or 48 hours. Our preliminary data suggest that a higher cross-brain content difference value is an important early variable associated with functional neurologic recovery after near-drowning. However, a single cross-brain oxygen content difference value must be interpreted with caution because considerable variability may occur among patient groups.

Cerebral blood flow, metabolic rate, and cross-brain oxygen consumption in brain injury

In six deeply comatose children, the relationships of intracranial pressure, cerebral perfusion pressure,cerebral blood flow, cross-brain oxygen consumption, and metabolic rate to outcome were studied sequentially during therapy. Intracranial pressure, cross-brain oxygen consumption, and metabolic rate values were significantly different in the three children who survived compared with those in the three who died. The differences in cross-brain oxygen consumption and metabolic rate occurred in the presence of clinically acceptable values for intracranial and cerebral perfusion pressures. Cross-brain oxygen consumption and metabolic rate may be important indicators of degree of neuronal injury, and of outcome.

Pediatric and neonatal critical care transport : A comparison of therapeutic interventions

Objective: To compare the therapeutic interventions provided to newborn and pediatric patients by a dedicated combined neonatal pediatric critical care transport team. Method: From November 1987 through December 1989 we prospectively compared the number of therapeutic interventions performed by the critical care transport team on newboras and pediatric patients. The transport team (critical care physician [PL3 or greater], pediatric respiratory therapist, critical care nurse), recorded all therapeutic interventions, including both procedural and pharmacologic, for 213 newborn and 149 pediatric consecutive transports. Data were analyzed by analysis of variance or x2 statistic. Results: All patients were admitted to either the pediatric or the neonatal intensive care unit, and over 80% of both age groups received assisted ventilation. Newborns commonly suffered from respiratory diseases (159/213), while pediatric patients suffered from respiratory (52/149), central nervous system (28/149), and traumatic conditions (37/149). Airway maintenance procedural interventions (intubation, ventilation) were the commonest in both groups, although more frequent in neonates. Neonates received antibiotics and morphine (P < 0.05) while pediatric patients received anticonvulsants and respiratory drugs (P < 0.05) more frequently. Newborns received significantly more interventions than pediatric patients (average 3.56 vs 2.93, P < 0.05). Newborns also received significantly more procedural interventions (2.06 vs 1.36, P=<0.05) including intubation (34.7% vs 15.4%, P < 0.05) and the initiation of mechanical ventilation (38% vs 22%, P < 0.05). Conclusions: Overall, newborns received more interventions, including intubation, and ventilation from the transport team than did pediatric patients. Our data suggest that combined pediatric neonatal transport teams should be prepared to intervene in a wide range of conditions from preterm respiratory distress to the multiply traumatized adolescent.

Adult respiratory distress syndrome in a child with acute epiglottitis.

Intubation of a 23-month-old child suffering epiglottitis was complicated by pulmonary edema progressing to the adult respiratory distress syndrome. Increased pulmonary shunt and pulmonary hypertension required high levels of positive end-expiratory pressure and prolonged mechanical ventilation to correct hypoxemia. A possible role for a cuffed endotracheal tube in epiglottitis is discussed.

Prototype volume-controlled neonatal/infant resuscitator

Face mask or bag endotracheal tube manual ventilation of neonates and infants has relied primarily on the use of self-inflating resuscitation devices (SIRs). While SIRs have the advantage of being simple to use and, therefore, require minimal training, recent research has demonstrated significant drawbacks to these devices. These drawbacks have included their large physical size, the tendency of such devices to cause significant hyperventilation, and the extreme variability of pressures necessary to activate the pop-off valve safety feature. This latter problem is especially serious in the infant where large pressure variations may increase the potential for pulmonary barotrauma. In an attempt to minimize the disadvantages of SIRs, we developed a prototype volume-controlled resuscitation device (VCD). We then compared the VCD to the SIRs in a cat model using blinded volunteer health care personnel previously familiar with SIRs only. Ventilation of the cat with the VCD yielded arterial and end-tidal CO2 values more closely resembling the physiologic state at a lower mean airway pressure. The data suggest that a human trial of manual ventilation with the prototype VCD is warranted.