Whitney J. McBride

Continuous thoracic epidural infusions for postoperative analgesia after pectus deformity repair

PURPOSE To determine whether continuous epidural analgesia after repair of a pectus deformity is a viable and safe alternative to high-dose narcotics in children. METHODS Data were collected prospectively for 19 children (4 to 17 years of age; 15 boys, 4 girls) who underwent pectus excavatum (14) or carinatum (5) repair between June 1, 1991 and July 1, 1994. Seventeen had a thoracic epidural catheter placed for postoperative pain control and two did not. The epidural catheter was routinely plead preoperatively by the anesthesiologist at the T3-T8 level, after induction of general anesthesia. Epidural catheters were test-dosed with local anesthesia alone or in combination with fentanyl, and afterward a continuous epidural infusion was maintained on the floor. Postoperative pain was assessed by nursing and house staff on the Wong-Baker scale, with adjustment of the dose rate or analgesic medication as appropriate. RESULTS All patients had extubation before leaving the operating room and were sent to the general pediatrics ward after leaving the recovery room. The average duration of the epidural was 69 hours (range, 20 to 116 hours). Sixteen patients received their test epidural dose preoperatively, and one patient had his in the recovery room. Fifteen epidural initially were dosed with bupivicaine (1 to 2 mg/kg) alone or in combination with fentanyl (1 to 2 micrograms/kg). Two patients received initial doses of lidocaine (1 to 1.5 micrograms/kg). Ten of 17 patients received fentanyl (1 microgram/kg/h) with bupivicaine (0.5 to 1.0 mg/kg/h) in the epidural as their maintenance medication, and the remainder received bupivicaine alone at the same dosage rate. Eight of 17 patients required additional intermittent supplemental narcotics, with an average of two doses of intravenous morphine per day (0.1 mg/kg) over the first 3 postoperative days. In contrast, the two patients who did not have an epidural catheter for pain control required high-dose intravenous morphine (0.2 mg/kg) every 2 to 3 hours for the first 3 to 4 postoperative days. No catheter-related complications occurred. CONCLUSION Thoracic epidural analgesia was completely successful in nine (53%) children who underwent repair of pectus deformity, and effectively reduced the intravenous narcotic demand in the other eight. Pain control was excellent, and no catheter-related complications were encountered. The data show that this method of analgesia in children is a safe and attractive alternative to intravenous narcotics, and eliminates the potential disadvantages of sedation and respiratory compromise.

Pulmonary embolism in pediatric trauma patients

Recent articles in the literature on adults have recommended prophylaxis for pulmonary embolism (PE) in selected trauma patients; however, to date no information is available regarding pediatric patients. We decided to investigate whether the incidence of PE in pediatric trauma patients is as high as that reported in adults, and identify those children who might be at high risk and benefit from prophylactic treatment. Utilizing the data from the National Pediatric Trauma Registry (NPTR), records were reviewed of all pediatric trauma patients (age < 19 years) admitted to the participating institutions between December 1987 and February 1993. Patients with documented PE were identified as well as those having associated risk factors as identified in adult trauma patients (deep venous thrombosis, extremity injury, spinal cord injury, and head injury). A total of 28,692 pediatric trauma patients were reviewed from the NPTR. The mean age was 9 years and the mean Injury Severity Score for the group was 11. Two thousand one children (7%) had serious head injuries (Glasgow Coma Scale score < 8), over 5700 (20%) had an isolated extremity injury, 290 had an identified spinal cord injury (108 with associated paralysis), and deep venous thrombosis was identified in 6 patients. Pulmonary embolism occurred in only two of the children in this series. Both patients with PE had spinal cord injuries with associated paraplegia, significant pulmonary injury, and high ISSs (25 and 27). The overall incidence of PE in the group was 0.000069%, and for those children with paralysis from spinal cord injury 1.85%.(ABSTRACT TRUNCATED AT 250 WORDS)

Perforation of the intrathoracic esophagus from blunt trauma in a child: Case report and review of the literature

Rupture of the intrathoracic esophagus from blunt trauma is an exceedingly rare injury in children and often presents on a delayed basis. The authors encountered a case of this unusual injury and review six additional cases found in the literature.

Four-dimensional analysis of human brain tumor spheroid invasion into fetal rat brain aggregates using confocal scanning laser microscopy

The advent of confocal microscopy and fluorescence probes has made possible the routine visualization of the complex three-dimensional structures of thick fixed or live specimens. Four-dimensional (4-D) imaging of biological specimens (three-dimensional image reconstruction of the same living sample at different time points), remains a seldom-used application of confocal microscopy. In the present study we used 4-D imaging techniques to quantitate the invasion of human brain tumor spheroids into fetal rat brain aggregates (FRBAs), using the vital fluorescence membrane dyes, 3,3′-Dioctadecyloxacarbocyanine perchlorate (DiO) and 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) as visualization probes. We found invasion patterns similar to the in vivo behavior of these tumors in the brain. Glioblastoma spheroids showed diffuse and circumscribed infiltration accompanied by cystic degeneration or necrosis of FRBAs. Spheroids from cerebral metastasis, however, showed a sharp delimitation of the invasive margin, and did not penetrate the FRBA beyond a depth of 55 µm. Measured rates of glioblastoma invasion varied with the tumor specimens examined. The slopes of the mid-portions of plots of % infiltration vs. time (hours) for four glioblastoma cell lines were 1.7 ± 0.21 (SD), 0.67 ± 0.11, 1.4 ± 0.22 and 1.3 ± 0.18. We conclude that confocal microscopy with vital fluorescence probes is a practical method that allows for close monitoring and quantitation of the process of invasion in live tissue preparations, and may be used for assessing the in vitro effects of various tumor treatments.

Diaspirin cross-linked hemoglobin resuscitation improves cerebral perfusion after head injury and shock

BACKGROUND Shock associated with traumatic brain injury (TBI) doubles the mortality of TBI alone by inducing a secondary ischemic injury. Rapid correction of cerebral perfusion pressure (CPP) is thought to be essential to improving outcome. Diaspirin cross-linked hemoglobin (DCLHb) has been shown to improve cerebral blood flow, increase mean arterial pressure (MAP), and reduce lesion size in models of occlusive cerebral ischemia but has not been evaluated in a model of TBI combined with hemorrhagic shock. METHODS We studied the effects of DCLHb resuscitation in a porcine model of cryogenic TBI and hemorrhagic shock (MAP = 50 mmHg). After combined insults, animals were randomized to receive a bolus of 4 mliters/kg of either lactated Ringers solution (n = 5) or DCLHb (n = 6). Lactated Ringers solution was then infused in both groups to maintain MAP at baseline. Shed blood was returned 1 hour after the initiation of resuscitation (R1). Animals were studied for 24 hours. RESULTS DCLHb infusion resulted in a significantly greater MAP at R1 and R24 (95 +/- 4 vs. 82 +/- 2 and 99 +/- 3 vs. 85 +/- 3 mm Hg, respectively) and a significantly greater CPP at R1 and R24 (83 +/- 10 vs. 68 +/- 5 and 89 +/- 6 vs. 71 +/- 11 mm Hg, respectively). Intracranial pressure was lower in the DCLHb group, but this difference was not significant. There was no significant difference between the groups in cerebral oxygen delivery. DCLHb animals required less fluid to maintain MAP (12,094 +/- 552 vs. 15,542 +/- 1094 mliters, p < 0.05). CONCLUSION These data suggest that DCLHb is beneficial in the early resuscitation of head injury and shock and that further investigation is warranted. Key Words: Diaspirin cross-linked hemoglobin, Head injury, Shock, Cerebral perfusion pressure.

Penetrating hepatic trauma in children: Operating room or not?

Nonoperative management has become widely accepted as the standard of care for patients with blunt hepatic trauma. Recent studies among adults have supported the use of nonoperative management of selective penetrating wounds to the hepatic bed in stable patients. The therapeutic management of children with penetrating injuries to the hepatic bed were evaluated to ascertain whether nonoperative management was a reasonable consideration in their care. The database of the National Pediatric Trauma Registry (NPTR) was reviewed for the period 1985-1994. ICD-9 codes 864.00 to 864.10 were used to select injury site, diagnosis, and, combined with Current Procedural Terminology (CPT) code data, to ascertain therapeutic interventions. The NPTR is a compilation of data from 61 pediatric trauma centers, currently held at Tufts University. The charts of 29,000 children were reviewed; of these, 1,147 sustained hepatic injuries, 132 (12%) of whom had a penetrating injury. The mechanism of injury was gunshot wound in 100 patients (76%) and stab wound in 32 (24%). The mean age of the children who had a penetrating injury was 12.7 years (range, in utero to 19 years). Six children were managed nonoperatively (5%), and 20 (15%) had negative laparotomy findings. Overall, 106 children sustained additional injuries that required surgical repair. There were 50 hollow viscous injury repair, 19 diaphragmatic repairs, 5 nephrectomies, 4 splenectomies, 4 pancreatic resections, and 43 significant hepatic repairs. The overall mortality rate was 9.8% (13 deaths). Nine of these patients died within 24 hours of injury. These data indicate that penetrating injury to the hepatic bed in children is associated with a high percentage of other organ injuries that require surgical intervention. This seems to be in direct contrast with the findings for adults, for whom the hepatic mass appears protective because of its larger size. The close anatomic proximity of the organs in a childs abdomen appears to make surgical intervention necessary for the majority of children with penetrating injury to the hepatic bed, and indicates that this approach should remain the standard of care for pediatric patients.

Allogeneic fetal intestinal transplantation with FK506 immunosuppression

PURPOSE Small intestinal transplantation remains a significant clinical problem. Allogeneic fetal intestinal (AFI) transplantation shows promise, particularly regarding procurement; however, no studiesto date have evaluated the potential success of true allogeneic loci implantation. The authors hypothesized that isolated segments of AFI could be heterotopically transplanted but would require immunosuppression to survive. METHODS Donor tissue was obtained from late-gestation Brown Norway rat fetuses with a histo-locus RTN and Fischer fetuses with a histo-locus RT1L. The recipients were adolescent male Fischer rats with a histo-locus RT1L. A 1.2-cm segment of fetal small bowel was implanted in the omentum of the recipient rat and allowed to mature for 5 weeks. Animals were then separated into five groups. Group A served as controls with syngeneic fetal intestinal (SFI) transplant. Group B received AFI with no immunosuppression; group C, AFI transplant with five days of FK506; group D, AFI with 10 days of FK506; and Group E, AFI with daily FK506 for the entire 5-week maturation period. Animals were killed on day 35. RESULTS All animals gained weight over the maturation period. Groups B, C, and D had no viable transplant segments at day 35. Groups A and E both had well-developed viable segments confirmed by gross and histological evaluation. CONCLUSIONS FK506 allows for normal intestinal development for use in allogeneic fetal bowel transplantation. With this observation, the use of fetal intestine transplanted into the portal circulation emerges as a potentially viable alternative to present intestinal transplant models.

Effect of low extracellular calcium on shortening velocity in isolated single smooth muscle cells

To understand how smooth muscle modulates its shortening velocity within the time course of a single contraction, the factors that govern crossbridge cycling in smooth muscle must be characterized. Since calcium plays an important role in regulation of the contractile apparatus, we studied the effect of lowering extracellular calcium on shortening velocity in single smooth muscle cells isolated enzymatically from the toad,Bufo marinus, stomach muscularis. Shortening velocity was estimated by three independent methods: (1) isotonic releases; (2) slack test; (3) video images of freely shortening cells. To determine the shortening velocity from isotonic releases and the slack test method, a single cell was attached at one end to an ultrasensitive force transducer and piezoelectric displacement device at its other end. At peak isometric force, in response to electrical stimulation, a series of isotonic releases to varying force levels were imposed and the resultant shortening responses used to construct force: velocity relationships in physiological saline containing low (0.18 mM) extracellular calcium. From force: velocity relationships and slack test data, an estimate of maximum shortening velocity (Vmax) was 0.19 cell lengths/s which was 3 times lower than in normal calcium (Warshaw 1987). AlthoughVmax was reduced in low extracellular calcium, the curvature of the force: velocity relationship estimated from the hyperbolic constant,a/Fmax, was unchanged (a/Fmax=0.17). Additional evidence for an effect of extracellular calcium on shortening velocity was obtained from shortening responses of freely shortening cells attached at one end only. Data from cells exposed first to low (0.18 mM) and then normal (1.8 mM) calcium suggest at least a twofold decrease in free shortening velocity with lower extracellular calcium. These results suggest that calcium exerts its effects by altering the rate constants for specific steps in the crossbridge cycle. For example, the lowerVmax would correlate with a reduction in the rate of crossbridge detachment.