Camille L. Stewart

Detection of Low-volume Blood Loss: Compensatory Reserve Versus Traditional Vital Signs

BACKGROUND Humans are able to compensate for low-volume blood loss with minimal change in traditional vital signs. We hypothesized that a novel algorithm, which analyzes photoplethysmogram (PPG) wave forms to continuously estimate compensatory reserve would provide greater sensitivity and specificity to detect low-volume blood loss compared with traditional vital signs. The compensatory reserve index (CRI) is a measure of the reserve remaining to compensate for reduced central blood volume, where a CRI of 1 represents supine normovolemia and 0 represents the circulating blood volume at which hemodynamic decompensation occurs; values between 1 and 0 indicate the proportion of reserve remaining. METHODS Subjects underwent voluntary donation of 1 U (approximately 450 mL) of blood. Demographic and continuous noninvasive vital sign wave form data were collected, including PPG, heart rate, systolic blood pressure, cardiac output, and stroke volume. PPG wave forms were later processed by the algorithm to estimate CRI values. RESULTS Data were collected from 244 healthy subjects (79 males and 165 females), with a mean (SD) age of 40.1 (14.2) years and mean (SD) body mass index of 25.6 (4.7). After blood donation, CRI significantly decreased in 92% (&agr; = 0.05; 95% confidence interval [CI], 88–95%) of the subjects. With the use of a threshold decrease in CRI of 0.05 or greater for the detection of 1 U of blood loss, the receiver operating characteristic area under the curve was 0.90, with a sensitivity of 0.84 and specificity of 0.86. In comparison, systolic blood pressure (52%; 95% CI, 45–59%), heart rate (65%; 95% CI, 58–72%), cardiac output (47%; 95% CI, 40–54%), and stroke volume (74%; 95% CI, 67–80%) changed in fewer subjects, had significantly lower receiver operating characteristic area under the curve values, and significantly lower specificities for detecting the same volume of blood loss. CONCLUSION Consistent with our hypothesis, CRI detected low-volume blood loss with significantly greater specificity than other traditional physiologic measures. These findings warrant further evaluation of the CRI algorithm in actual trauma settings. LEVEL OF EVIDENCE Diagnostic study, level II.

Early tracheostomy improves outcomes in severely injured children and adolescents

BACKGROUND Early tracheostomy has been advocated for adult trauma patients to improve outcomes and resource utilization. We hypothesized that timing of tracheostomy for severely injured children would similarly impact outcomes. METHODS Injured children undergoing tracheostomy over a 10-year period (2002-2012) were reviewed. Early tracheostomy was defined as post-injury day ≤ 7. Data were compared using Students t test, Pearson chi-squared test and Fisher exact test. Statistical significance was set at p<0.05 with 95% confidence intervals. RESULTS During the 10-year study period, 91 patients underwent tracheostomy following injury. Twenty-nine (32%) patients were < 12 years old; of these, 38% received early tracheostomy. Sixty-two (68%) patients were age 13 to 18; of these, 52% underwent early tracheostomy. Patients undergoing early tracheostomy had fewer ventilator days (p=0.003), ICU days (p=0.003), hospital days (p=0.046), and tracheal complications (p=0.03) compared to late tracheostomy. There was no difference in pneumonia (p=0.48) between early and late tracheostomy. CONCLUSION Children undergoing early tracheostomy had improved outcomes compared to those who underwent late tracheostomy. Early tracheostomy should be considered for the severely injured child. SUMMARY Early tracheostomy is advocated for adult trauma patients to improve patient comfort and resource utilization. In a review of 91 pediatric trauma patients undergoing tracheostomy, those undergoing tracheostomy on post-injury day ≤ 7 had fewer ventilator days, ICU days, hospital days, and tracheal complications compared to those undergoing tracheostomy after post-injury day 7.

Helicopter versus ground emergency medical services for the transportation of traumatically injured children

BACKGROUND Helicopter emergency medical services (HEMS) are a common mode of transportation for pediatric trauma patients. We hypothesized that HEMS improve outcomes for traumatically injured children compared to ground emergency medical services (GEMS). METHODS We queried trauma registries of two level 1 pediatric trauma centers for children 0-17 years, treated from 2003 to 2013, transported by HEMS or GEMS, with known transport starting location and outcome. A geocoding service estimated travel distance and time. Multivariate regression analyses were performed to adjust for injury severity variables and travel distance/time. RESULTS We identified 14,405 traumatically injured children; 3870 (26.9%) transported by HEMS and 10,535 (73.1%) transported by GEMS. Transport type was not significantly associated with survival, ICU length of stay, or discharge disposition. Transport by GEMS was associated with a 68.6%-53.1% decrease in hospital length of stay, depending on adjustment for distance/time. Results were similar for children with severe injuries, and with propensity score matched cohorts. Of note, 862/3850 (22.3%) of HEMS transports had an ISS<10 and hospitalization<1 day. CONCLUSIONS HEMS do not independently improve outcomes for traumatically injured children, and 22.3% of children transported by HEMS are not significantly injured. These factors should be considered when requesting HEMS for transport of traumatically injured children.

The Compensatory Reserve Index Following Injury: Results of a Prospective Clinical Trial.

Introduction: Humans are able to compensate for significant blood loss with little change in traditional vital signs. We hypothesized that an algorithm, which recognizes compensatory changes in photoplethysmogram (PPG) waveforms, could detect active bleeding and ongoing volume loss in injured patients. Methods: Injured adults were prospectively enrolled at a level I trauma center. PPG data collection was conducted using a custom-made pulse oximeter. Waveform data were post-processed by an algorithm to calculate the compensatory reserve index (CRI), measured on a scale of 1 to 0, with 1 indicating fully compensated and 0 indicating no reserve, or decompensation. CRI was compared to clinical findings. Results: Fifty patients were enrolled in the study; 3 had incomplete data, 3 had indeterminate bleeding, 12 were actively bleeding, and 32 were not bleeding. The mean initial CRI of bleeding patients was significantly lower compared with the non-bleeding patients (CRI 0.17, 95% CI = 0.13–0.22 vs. CRI 0.56, 95% CI = 0.49–0.62, P < 0.001). Using a cut-off of 0.21 had a sensitivity of 0.97 and specificity of 0.83 for identifying bleeding patients. CRI had a higher sensitivity than heart rate (75%), systolic blood pressure (63%), shock index (27%), base deficit (29%), lactate (80%), hemoglobin (50%), and hematocrit (50%). During ongoing bleeding, CRI decreased following fluid resuscitation, and conversely increased for patients who were not bleeding. Conclusions: A novel computational algorithm that recognizes subtle changes in PPG waveforms can quickly and noninvasively discern which patients are actively bleeding and continuing to bleed with high sensitivity and specificity in acutely injured patients.

Helmet use and injury severity among pediatric skiers and snowboarders in Colorado

INTRODUCTION Skiing and snowboarding are popular winter recreational activities that are commonly associated with orthopedic type injuries. Unbeknownst to most parents, however, are the significant but poorly described risks for head, cervical spine and solid organ injuries. Although helmet use is not mandated for skiers and snowboarders outside of resort sponsored activities, we hypothesized that helmet use is associated with a lower risk of severe head injury, shorter ICU stay and shorter hospital length of stay. METHODS The trauma registry at a level I pediatric trauma center in the state of Colorado was queried for children ages 3-17years, who sustained an injury while skiing or snowboarding from 1/1/1999 to 12/31/2014. Injury severity was assessed by Abbreviated Injury Severity (AIS) score, injury severity score (ISS) and admission location. Head injury was broadly defined as any trauma to the body above the lower border of the mandible. Regression analysis was used to test associations of variables with injury severity. RESULTS 549 children sustained snow sport related injuries during the 16year study period. The mean patient age was11±3years, most were male (74%) and the majority were Colorado residents (54%). The overall median ISS was 9 (IQR 4-9) and 78 children (14%) were admitted to the ICU. Colorado residents were nearly twice as likely to be wearing a helmet at the time of injury, compared to visitors from out-of-state (adjusted OR 1.86, 95% CI 1.24-2.76, p=0.002). In a multivariate analysis injury severity was significantly associated with injury while skiing (p=0.026), helmet use (p=0.0416), and sustaining a head injury (p<0.0001). In a separate multivariate analysis ICU admission was associated with head injury (p<0.0001) and wearing a helmet (p=0.0257); however, those wearing a helmet and admitted to the ICU had significantly lower ISS (p=0.007) and head AIS (p=0.011) scores than those who were not wearing a helmet at the time of injury. CONCLUSION Visitors from out of state were less likely to be wearing a helmet when injured and more likely to be severely injured, suggesting Colorado residents have a better understanding of the benefits of helmet usage. Helmeted skiers and snowboarders who were admitted to the ICU had significantly lower ISS and head AIS scores than those who were not helmeted. Pediatric skiers, snowboarders and their parents should be educated on the significant risks associated with these activities and the benefits of helmet usage. LEVEL OF EVIDENCE III.

Factors associated with peritoneal dialysis catheter complications in children.

BACKGROUND/PURPOSE Peritoneal dialysis (PD) is a common method of renal replacement therapy for children. However, placement of PD catheters has risk, and some are never used. METHODS We conducted a retrospective chart review of children with a PD catheter placed between 2000 and 2014. Logistic regression analyses were used to identify covariates associated with complications. RESULTS We identified 175 children with PD catheters. 110 complications developed in 80 children (45.7%). Complications including unexpected return to the operating room and peritonitis increased as the length of time a catheter was in place increased. Children who weighed <12.4 kg had 3.2 times greater odds of developing a leak (95% CI 1.21-8.63, p=0.02). Twelve children never used their PD catheters, 9 with acute kidney injury (AKI) who recovered from their disease more quickly than expected. No covariate was associated with nonuse. CONCLUSIONS Complications with PD catheters are common and increase the longer catheters are in place. Lower weight children are at greater risk of PD catheter leak. Decreased initial volumes of dialysate in smaller children may mitigate this risk. Nonuse may be reduced if dialysis is permitted the day of placement for children with AKI.

When is it safe to forgo abdominal CT in blunt-injured children?

INTRODUCTION CT is the standard modality to diagnose solid organ injury after blunt trauma; however, the associated radiation carries a risk of cancer. We hypothesized that there are patient-specific factors that can identify those children who require abdominal CT. METHODS We reviewed all children admitted to 2 pediatric trauma centers after blunt trauma with liver or spleen injury from January 2009 to December 2013. The low-risk group was defined as a Glasgow Coma Scale (GCS) of 15 with normal pediatric age-adjusted shock index (heart rate/systolic blood pressure; SIPA) on presentation, and injury attributable to a single, nonmotorized, blunt force to the abdomen. The at-risk group did not meet these criteria. RESULTS We identified 206 children with blunt liver or spleen injury, 101 of whom met the low-risk criteria. Among these 101 children who met the low-risk criteria, there were no deaths, no children required laparotomy, only 1 child required a packed red cell transfusion, and no children required discharge to a rehabilitation facility. CONCLUSION Children who present to the emergency department after blunt abdominal trauma by a nonmotorized force with a normal GCS and SIPA are unlikely to have a solid organ injury that will require intervention.

Base deficit correlates with mortality in pediatric abusive head trauma.

BACKGROUND/PURPOSE Children suffering from abusive head trauma (AHT) have worse outcomes compared to non-AHT, but the reasons for this are unclear. We hypothesized that delayed medical care associated with AHT causes prolonged pre-hospital hypotension and hypoxia as measured by admission base deficit (BD), and that this would correlate with outcome. METHODS We performed a 10-year retrospective chart review of children admitted for AHT at two academic level-I trauma centers. Statistics were performed using Students t test, chi-square analysis, and multivariate logistic regression, and considered significant at p < 0.05. RESULTS Four-hundred twelve children with AHT were identified, and admission BD was drawn for 148/412 (36%) children, including 104 survivors and 44 non-survivors. Non-survivors had significantly higher BD compared to survivors (12.6 ± 1.6 versus 5.3 ± 0.6, p < 0.001). Non-survivors were more likely to be intubated pre-hospital and get cardiopulmonary resuscitation (CPR) (p < 0.001). Mortality increased with rising BD, according to CPR status. There was no difference in patterns of brain injury between survivors and non-survivors (p > 0.05). CONCLUSIONS BD correlates with mortality in children suffering severe AHT. Non-survivors are also more likely to be intubated pre-hospital and require CPR, with no difference in pattern of brain injury, suggesting that secondary injury is a major determinant of outcome in severe AHT.

Rectal biopsies for Hirschsprung disease: Patient characteristics by diagnosis and attending specialty

PURPOSE Hirschsprung disease (HD) is diagnosed with rectal biopsy. At our institution two services perform these biopsies: pediatric surgery and gastroenterology. Our objective was to review our institutional experience with rectal biopsies to diagnose HD and compare patients and outcomes between the two services. METHODS We reviewed all children undergoing a rectal biopsy for the evaluation of HD at our institution over a 10-year period. Comparisons were made using multiple logistic regression models. RESULTS We identified 518 children who underwent rectal biopsy for evaluation of HD; 451/518 (87%) were adequate and 56/518 (11%) were positive for HD. A positive biopsy was more likely with delayed passage of meconium (p<0.001), obstructive symptoms (p<0.001), trisomy 21 (p<0.001), full-term gestation (p=0.03), and male gender (p=0.02). Pediatric surgeons biopsied younger patients with more classic symptoms for HD compared to gastroenterologists. Pediatric surgeons were more likely to take adequate (OR 6.0, 95% CI 2.9-12.4, p<0.001) and positive biopsies (OR 6.7 95% CI 2.1-21.2, p=0.001) compared to gastroenterologists. CONCLUSION Infants with classic symptoms can reliably be diagnosed with HD by a pediatric surgeon. The work up for HD in older children with constipation should be a collaborative effort between pediatric surgery and gastroenterology.

Infant car safety seats and risk of head injury.

BACKGROUND/PURPOSE We observed a high incidence of traumatic brain injuries (TBI) in properly restrained infants involved in higher speed motor vehicle crashes (MVCs). We hypothesized that car safety seats are inadequately protecting infants from TBI. METHODS We retrospectively queried scene crash data from our State Department of Transportation (2007-2011) and State Department of Public Health data (2000-2011) regarding infants who presented to a trauma center after MVC. RESULTS Department of Transportation data revealed 94% of infants in MVCs were properly restrained (782/833) with average speed of 44.6 miles/h when there was concern for injury. Department of Public Health data showed only 67/119 (56.3%) of infants who presented to a trauma center after MVC were properly restrained. Properly restrained infants were 12.7 times less likely to present to a trauma center after an MVC (OR=12.7, CI 95% 5.6-28.8, p<0.001). TBI was diagnosed in 73/119 (61.3%) infants; 42/73 (57.5%) properly restrained, and 31/73 (42.5%) improperly/unrestrained (p=0.34). Average head abbreviated injury scale was similar for properly restrained (3.2±0.2) and improperly/unrestrained infants (3.5±0.2, p=0.37). CONCLUSION Car safety seats prevent injuries. However, TBI is similar among properly restrained and improperly/unrestrained infants involved in higher speed MVCs who present to a trauma center.