Evaluating the Regional Differences in Pediatric Injury Patterns During the COVID-19 Pandemic.

INTRODUCTION: Reports of pediatric injury patterns during the COVID-19 pandemic are conflicting and lack the granularity to explore differences across regions. We hypothesized there would be considerable variation in injury patterns across pediatric trauma centers in the United States. MATERIALS AND METHODS: A multicenter, retrospective study evaluating patients <18 y old with traumatic injuries meeting National Trauma Data Bank criteria was performed. Patients injured after stay-at-home orders through September 2020 ("COVID" cohort) were compared to "Historical" controls from an averaged period of equivalent dates in 2016-2019. Differences in injury type, intent, and mechanism were explored at the site level. RESULTS: 47,385 pediatric trauma patients were included. Overall trauma volume increased during the COVID cohort compared to the Historical (COVID 7068 patients versus Historical 5891 patients); however, some sites demonstrated a decrease in overall trauma of 25% while others had an increase of over 33%. Bicycle injuries increased at every site, with a range in percent change from 24% to 135% increase. Although the greatest net increase was due to blunt injuries, there was a greater relative increase in penetrating injuries at 7/9 sites, with a range in percent change from a 110% increase to a 69% decrease. CONCLUSIONS: There was considerable discrepancy in pediatric injury patterns at the individual site level, perhaps suggesting a variable impact of the specific sociopolitical climate and pandemic policies of each catchment area. Investigation of the unique response of the community during times of stress at pediatric trauma centers is warranted to be better prepared for future environmental stressors.

Pediatric Injury Transfer Patterns During the COVID-19 Pandemic: An Interrupted time Series Analysis.

INTRODUCTION: With the expected surge of adult patients with COVID-19, the Children's Hospital Association recommended a tiered approach to divert children to pediatric centers. Our objective was understanding changes in interfacility transfer to Pediatric Trauma Centers (PTCs) during the first 6 mo of the pandemic. METHODS: Children aged < 18 y injured between January 1, 2016 and September 30, 2020, who met National Trauma Databank inclusion criteria from 9 PTCs were included. An interrupted time-series analysis was used to estimate an expected number of transferred patients compared to observed volume. The "COVID" cohort was compared to a historical cohort (historical average [HA]), using an average across 2016-2019. Site-based differences in transfer volume, demographics, injury characteristics, and hospital-based outcomes were compared between cohorts. RESULTS: Twenty seven thousand thirty one/47,382 injured patients (57.05%) were transferred to a participating PTC during the study period. Of the COVID cohort, 65.4% (4620/7067) were transferred, compared to 55.7% (3281/5888) of the HA (P < 0.001). There was a decrease in 15-y-old to 17-y-old patients (10.43% COVID versus 12.64% HA, P = 0.003). More patients in the COVID cohort had injury severity scores ≤ 15 (93.25% COVID versus 87.63% HA, P < 0.001). More patients were discharged home after transfer (31.80% COVID versus 21.83% HA, P < 0.001). CONCLUSIONS: Transferred trauma patients to Level I PTC increased during the COVID-19 pandemic. The proportion of transferred patients discharged from emergency departments increased. Pediatric trauma transfers may be a surrogate for referring emergency department capacity and resources and a measure of pediatric trauma triage capability.

Venous Thromboembolism Prophylaxis in High-Risk Pediatric Trauma Patients.

Importance: The indications, safety, and efficacy of chemical venous thromboembolism prophylaxis (cVTE) in pediatric trauma patients remain unclear. A set of high-risk criteria to guide cVTE use was recently recommended; however, these criteria have not been evaluated prospectively. Objective: To examine high-risk criteria and cVTE use in a prospective multi-institutional study of pediatric trauma patients. Design, Setting, and Participants: This cohort study was completed between October 2019 and October 2022 in 8 free-standing pediatric hospitals designated as American College of Surgeons level I pediatric trauma centers. Participants were pediatric trauma patients younger than 18 years who met defined high-risk criteria on admission. It was hypothesized that cVTE would be safe and reduce the incidence of VTE. Exposures: Receipt and timing of chemical VTE prophylaxis. Main Outcomes and Measures: The primary outcome was overall VTE rate stratified by receipt and timing of cVTE. The secondary outcome was safety of cVTE as measured by bleeding or other complications from anticoagulation. Results: Among 460 high-risk pediatric trauma patients, the median (IQR) age was 14.5 years (10.4-16.2 years); 313 patients (68%) were male and 147 female (32%). The median (IQR) Injury Severity Score (ISS) was 23 (16-30), and median (IQR) number of high-risk factors was 3 (2-4). A total of 251 (54.5%) patients received cVTE; 62 (13.5%) received cVTE within 24 hours of admission. Patients who received cVTE after 24 hours had more high-risk factors and higher ISS. The most common reason for delayed cVTE was central nervous system bleed (120 patients; 30.2%). There were 28 VTE events among 25 patients (5.4%). VTE occurred in 1 of 62 patients (1.6%) receiving cVTE within 24 hours, 13 of 189 patients (6.9%) receiving cVTE after 24 hours, and 11 of 209 (5.3%) who had no cVTE (P = .31). Increasing time between admission and cVTE initiation was significantly associated with VTE (odds ratio, 1.01; 95% CI, 1.00-1.01; P = .01). No bleeding complications were observed while patients received cVTE. Conclusions and Relevance: In this prospective study, use of cVTE based on a set of high-risk criteria was safe and did not lead to bleeding complications. Delay to initiation of cVTE was significantly associated with development of VTE. Quality improvement in pediatric VTE prevention may center on timing of prophylaxis and barriers to implementation.

Pediatric injury trends and relationships with social vulnerability during the COVID-19 pandemic: A multi-institutional analysis.

BACKGROUND: The impact of the COVID-19 pandemic on pediatric injury, particularly relative to a community's vulnerability, is unknown. The objective of this study was to describe the change in pediatric injury during the first 6 months of the COVID-19 pandemic compared with prior years, focusing on intentional injury relative to the social vulnerability index (SVI). METHODS: All patients younger than 18 years meeting inclusion criteria for the National Trauma Data Bank between January 1, 2016, and September 30, 2020, at nine Level I pediatric trauma centers were included. The COVID cohort (children injured in the first 6 months of the pandemic) was compared with an averaged historical cohort (corresponding dates, 2016-2019). Demographic and injury characteristics and hospital-based outcomes were compared. Multivariable logistic regression was used to estimate the adjusted odds of intentional injury associated with SVI, moderated by exposure to the pandemic. Interrupted time series analysis with autoregressive integrated moving average modeling was used to predict expected injury patterns. Volume trends and observed versus expected rates of injury were analyzed. RESULTS: There were 47,385 patients that met inclusion criteria, with 8,991 treated in 2020 and 38,394 treated in 2016 to 2019. The COVID cohort included 7,068 patients and the averaged historical cohort included 5,891 patients (SD, 472), indicating a 20% increase in pediatric injury ( p = 0.031). Penetrating injuries increased (722 [10.2%] COVID vs. 421 [8.0%] historical; p < 0.001), specifically firearm injuries (163 [2.3%] COVID vs. 105 [1.8%] historical; p = 0.043). Bicycle collisions (505 [26.3%] COVID vs. 261 [18.2%] historical; p < 0.001) and collisions on other land transportation (e.g., all-terrain vehicles) (525 [27.3%] COVID vs. 280 [19.5%] historical; p < 0.001) also increased. Overall, SVI was associated with intentional injury (odds ratio, 7.9; 95% confidence interval, 6.5-9.8), a relationship which increased during the pandemic. CONCLUSION: Pediatric injury increased during the pandemic across multiple sites and states. The relationship between increased vulnerability and intentional injury increased during the pandemic. LEVEL OF EVIDENCE: Prognostic and Epidemiological; Level III.

Relationship between the COVID-19 pandemic and structural inequalities within the pediatric trauma population.

BACKGROUND: The COVID-19 pandemic disrupted social, political, and economic life across the world, shining a light on the vulnerability of many communities. The objective of this study was to assess injury patterns before and after implementation of stay-at-home orders (SHOs) between White children and children of color and across varying levels of vulnerability based upon children's home residence. METHODS: A multi-institutional retrospective study was conducted evaluating patients < 18 years with traumatic injuries. A "Control" cohort from an averaged March-September 2016-2019 time period was compared to patients injured after SHO initiation-September 2020 ("COVID" cohort). Interactions between race/ethnicity or social vulnerability index (SVI), a marker of neighborhood vulnerability and socioeconomic status, and the COVID-19 timeframe with regard to the outcomes of interest were assessed using likelihood ratio Chi-square tests. Differences in injury intent, type, and mechanism were then stratified and explored by race/ethnicity and SVI separately. RESULTS: A total of 47,385 patients met study inclusion. Significant interactions existed between race/ethnicity and the COVID-19 SHO period for intent (p < 0.001) and mechanism of injury (p < 0.001). There was also significant interaction between SVI and the COVID-19 SHO period for mechanism of injury (p = 0.01). Children of color experienced a significant increase in intentional (COVID 16.4% vs. Control 13.7%, p = 0.03) and firearm (COVID 9.0% vs. Control 5.2%, p < 0.001) injuries, but no change was seen among White children. Children from the most vulnerable neighborhoods suffered an increase in firearm injuries (COVID 11.1% vs. Control 6.1%, p = 0.001) with children from the least vulnerable neighborhoods having no change. All-terrain vehicle (ATV) and bicycle crashes increased for children of color (COVID 2.0% vs. Control 1.1%, p = 0.04 for ATV; COVID 6.7% vs. Control 4.8%, p = 0.02 for bicycle) and White children (COVID 9.6% vs. Control 6.2%, p < 0.001 for ATV; COVID 8.8% vs. Control 5.8%, p < 0.001 for bicycle). CONCLUSIONS: In contrast to White children and children from neighborhoods of lower vulnerability, children of color and children living in higher vulnerability neighborhoods experienced an increase in intentional and firearm-related injuries during the COVID-19 pandemic. Understanding inequities in trauma burden during times of stress is critical to directing resources and targeting intervention strategies.

A Multi-institutional Study Evaluating Pediatric Burn Injuries During the COVID-19 Pandemic.

During the COVID-19 pandemic, children were out of school due to Stay-at-Home Orders. The objective of this study was to investigate how the COVID-19 pandemic may have impacted the incidence of burn injuries in children. Eight Level I Pediatric Trauma Centers participated in a retrospective study evaluating children <18 years old with traumatic injuries defined by the National Trauma Data Bank. Patients with burn injuries were identified by ICD-10 codes. Historical controls from March to September 2019 ("Control" cohort) were compared to patients injured after the start of the COVID-19 pandemic from March to September 2020 ("COVID" cohort). A total of 12,549 pediatric trauma patients were included, of which 916 patients had burn injuries. Burn injuries increased after the start of the pandemic (COVID 522/6711 [7.8%] vs Control 394/5838 [6.7%], P = .03). There were no significant differences in age, race, insurance status, burn severity, injury severity score, intent or location of injury, and occurrence on a weekday or weekend between cohorts. There was an increase in flame burns (COVID 140/522 [26.8%] vs Control 75/394 [19.0%], P = .01) and a decrease in contact burns (COVID 118/522 [22.6%] vs Control 112/394 [28.4%], P = .05). More patients were transferred from an outside institution (COVID 315/522 patients [60.3%] vs Control 208/394 patients [52.8%], P = .02), and intensive care unit length of stay increased (COVID median 3.5 days [interquartile range 2.0-11.0] vs Control median 3.0 days [interquartile range 1.0-4.0], P = .05). Pediatric burn injuries increased after the start of the COVID-19 pandemic despite Stay-at-Home Orders intended to optimize health and increase public safety.

The COVID-19 pandemic and associated rise in pediatric firearm injuries: A multi-institutional study.

BACKGROUND: Firearm sales in the United States (U.S.) markedly increased during the COVID-19 pandemic. Our objective was to determine if firearm injuries in children were associated with stay-at-home orders (SHO) during the COVID-19 pandemic. We hypothesized there would be an increase in pediatric firearm injuries during SHO. METHODS: This was a multi institutional, retrospective study of institutional trauma registries. Patients <18 years with traumatic injuries meeting National Trauma Data Bank (NTDB) criteria were included. A "COVID" cohort, defined as time from initiation of state SHO through September 30, 2020 was compared to "Historical" controls from an averaged period of corresponding dates in 2016-2019. An interrupted time series analysis (ITSA) was utilized to evaluate the association of the U.S. declaration of a national state of emergency with pediatric firearm injuries. RESULTS: Nine Level I pediatric trauma centers were included, contributing 48,111 pediatric trauma patients, of which 1,090 patients (2.3%) suffered firearm injuries. There was a significant increase in the proportion of firearm injuries in the COVID cohort (COVID 3.04% vs. Historical 1.83%; p < 0.001). There was an increased cumulative burden of firearm injuries in 2020 compared to a historical average. ITSA showed an 87% increase in the observed rate of firearm injuries above expected after the declaration of a nationwide emergency (p < 0.001). CONCLUSION: The proportion of firearm injuries affecting children increased during the COVID-19 pandemic. The pandemic was associated with an increase in pediatric firearm injuries above expected rates based on historical patterns.

Impact of "Stay-at-Home" orders on non-accidental trauma: A multi-institutional study.

BACKGROUND: It is unclear how Stay-at-Home Orders (SHO) of the COVID-19 pandemic impacted the welfare of children and rates of non-accidental trauma (NAT). We hypothesized that NAT would initially decrease during the SHO as children did not have access to mandatory reporters, and then increase as physicians' offices and schools reopened. METHODS: A multicenter study evaluating patients <18 years with ICD-10 Diagnosis and/or External Cause of Injury codes meeting criteria for NAT. "Historical" controls from an averaged period of March-September 2016-2019 were compared to patients injured March-September 2020, after the implementation of SHO ("COVID" cohort). An interrupted time series analysis was utilized to evaluate the effects of SHO implementation. RESULTS: Nine Level I pediatric trauma centers contributed 2064 patients meeting NAT criteria. During initial SHO, NAT rates dropped below what was expected based on historical trends; however, thereafter the rate increased above the expected. The COVID cohort experienced a significant increase in the proportion of NAT patients age ≥5 years, minority children, and least resourced as determined by social vulnerability index (SVI). CONCLUSIONS: The COVID-19 pandemic affected the presentation of children with NAT to the hospital. In times of public health crisis, maintaining systems of protection for children remain essential. LEVEL OF EVIDENCE: III.

A Multicenter Evaluation of a Firearm Safety Intervention in the Pediatric Outpatient Setting.

PURPOSE: Firearm injuries continue to be a common cause of injury for American children. This pilot study was developed to evaluate the feasibility of providing guidance about firearm safety to the parents of pediatric patients using a tablet-based module in the outpatient setting. METHODS: A tablet-based questionnaire that included a firearm safety message based on current best practice was administered to parents of pediatric patients at nine centers in 2018. Parents were shown a firearm safety video and then asked a series of questions related to firearm safety. RESULTS: The study was completed by 543 parents from 15 states. More than one-third (37%) of families kept guns in their home. The majority of parents (81%, n = 438) thought it was appropriate for physicians to provide firearm safety counseling. Two-thirds (63%) of gun owning parents who do not keep their guns locked said that the information provided in the module would change the way they stored firearms at home. CONCLUSION: Use of a tablet based firearm safety module in the outpatient setting is feasible, and the majority of parents are receptive to receiving anticipatory guidance on firearm safety. Further data is needed to evaluate whether the intervention will improve firearm safety practices in the home. LEVEL OF EVIDENCE: Level III.

Changing the Paradigm for Management of Pediatric Primary Spontaneous Pneumothorax: A Simple Aspiration Test Predicts Need for Operation.

PURPOSE: Chest tube (CT) management for pediatric primary spontaneous pneumothorax (PSP) is associated with long hospital stays and high recurrence rates. To streamline management, we explored simple aspiration as a test to predict need for surgery. METHODS: A multi-institution, prospective pilot study of patients with first presentation for PSP at 9 children's hospitals was performed. Aspiration was performed through a pigtail catheter, followed by 6 h observation with CT clamped. If pneumothorax recurred during observation, the aspiration test failed and subsequent management was per surgeon discretion. RESULTS: Thirty-three patients were managed with simple aspiration. Aspiration was successful in 16 of 33 (48%), while 17 (52%) failed the aspiration test and required hospitalization. Twelve who failed aspiration underwent CT management, of which 10 (83%) failed CT management owing to either persistent air leak requiring VATS or subsequent PSP recurrence. Recurrence rate was significantly greater in the group that failed aspiration compared to the group that passed aspiration [10/12 (83%) vs 7/16 (44%), respectively, P=0.028]. CONCLUSION: Simple aspiration test upon presentation with PSP predicts chest tube failure with 83% positive predictive value. We recommend changing the PSP management algorithm to include an initial simple aspiration test, and if that fails, proceed directly to VATS. TYPE OF STUDY: Prospective pilot study LEVEL OF EVIDENCE: Level III.

Management differences for pediatric solid organ injuries in a rural state.

Pediatric liver and spleen injuries are frequently treated in specialized hospitals. Not all injured children, however, are treated in referral centers. We evaluated the management of pediatric liver and spleen injuries in a rural state without a state trauma system to determine if differences existed between trauma centers and nontrauma centers. A state database was queried for patients < or = 15-years-old who suffered liver and spleen injuries from 2003 to 2005. Iatrogenic injuries were excluded. There were 115 pediatric liver and 183 pediatric spleen injuries. Fifty per cent of liver and 63 per cent of spleen injuries in nontrauma centers were isolated solid organ injuries compared with 18 per cent and 36 per cent, respectively, in trauma centers. The mortality rate for both liver and spleen injuries was similar in trauma and nontrauma centers. Hospital charges were higher in trauma centers but this was due to patients with associated injuries. The nonoperative management rate was similar for liver injuries. Pediatric patients with splenic injuries had a lower rate of nonoperative management in nontrauma centers (75% to 90%, nontrauma vs trauma). In Kentucky, pediatric solid organ injuries are usually managed nonoperatively in both trauma and nontrauma centers, but trauma centers cared for fewer isolated solid organ injuries.

Clinical clearance of the cervical spine in blunt trauma patients younger than 3 years: a multi-center study of the american association for the surgery of trauma.

BACKGROUND: Cervical spine clearance in the very young child is challenging. Radiographic imaging to diagnose cervical spine injuries (CSI) even in the absence of clinical findings is common, raising concerns about radiation exposure and imaging-related complications. We examined whether simple clinical criteria can be used to safely rule out CSI in patients younger than 3 years. METHODS: The trauma registries from 22 level I or II trauma centers were reviewed for the 10-year period (January 1995 to January 2005). Blunt trauma patients younger than 3 years were identified. The measured outcome was CSI. Independent predictors of CSI were identified by univariate and multivariate analysis. A weighted score was calculated by assigning 1, 2, or 3 points to each independent predictor according to its magnitude of effect. The score was established on two thirds of the population and validated using the remaining one third. RESULTS: Of 12,537 patients younger than 3 years, CSI was identified in 83 patients (0.66%), eight had spinal cord injury. Four independent predictors of CSI were identified: Glasgow Coma Score <14, GCSEYE = 1, motor vehicle crash, and age 2 years or older. A score of <2 had a negative predictive value of 99.93% in ruling out CSI. A total of 8,707 patients (69.5% of all patients) had a score of <2 and were eligible for cervical spine clearance without imaging. There were no missed CSI in this study. CONCLUSIONS: CSI in patients younger than 3 years is uncommon. Four simple clinical predictors can be used in conjunction to the physical examination to substantially reduce the use of radiographic imaging in this patient population.

An analysis of risk-taking behavior among adolescent blunt trauma patients.

INTRODUCTION: The impact of risk-taking behavior among adolescent blunt trauma patients is not fully appreciated. This study examined the relationship between adolescent risk-taking behaviors, the resultant injury severity, and outcome for blunt trauma. METHODS: Between January 2000 and December 2005, data were collected on adolescent blunt trauma patients (12-18 years) admitted to either a Level I adult trauma center or large urban pediatric hospital. Five groups of risk-taking behavior were examined: ATV riders, drug and alcohol users, unhelmeted motorcyclists, unhelmeted extreme sports participants and unrestrained motor vehicle occupants. Demographic data, mechanism of injury, injury severity, hospital course and outcomes were evaluated for each group. RESULTS: A total of 2030 adolescents were admitted following blunt trauma; 723 adolescents (36%) were engaged in risk-taking behavior at the time of their injury. Most patients were male (68%). Unrestrained MVA occupants were the most frequently encountered risk takers (37%); among this subset, most were unrestrained passengers (74%). Head injuries were frequent (22%) among risk takers. When compared to non-risk-takers, there were no significant age, race, gender, or ISS differences. However, a significantly higher number of positive head CT scans were found among risk-taking adolescents (22%, p < 0.05). Mortality was low (3%). CONCLUSIONS: Risk-taking behavior is prevalent among adolescent blunt trauma patients. Improved injury prevention strategies are needed to discourage these behaviors during adolescence.

Blunt liver injury in children and adults: is there really a difference?

Hepatic injuries are increasingly managed nonoperatively with the availability of adjunctive procedures such as angiography, ERCP, and percutaneous drainage. Although extensively discussed in the adult population, little has been reported on outcomes and management of pediatric liver injury. Retrospective review of all patients with blunt liver injuries admitted to an adult Level I trauma center and pediatric trauma center within the same community was performed from 2004 to 2006. The necessity for operation, adjuncts to nonoperative management, and outcome were collected and compared for the pediatric (PED) (<18 years of age) versus the adult (> or = 18 years of age) injured patients. There were 389 liver injuries identified (PED = 90, adult = 299); 25 per cent of adult injuries were greater than or equal to grade III, while 23 per cent of PED injuries were high-grade injuries. Each group of patients had similar rates of primary operative intervention: adult patients (18%) versus PED patients (16%). Adjunctive therapies were rarely used in the PED patients with only one patient requiring a percutaneous drain and one patient undergoing ERCP twice. Conversely, the adult patient group required eight percutaneous drains, 15 angiograms, 6 ERCPs and 14 laparoscopic abdominal washout procedures. ICU and hospital LOS were 25 per cent and 33 per cent lower in the adult population for high-grade injuries. The overall mortality rates were similar at 7 per cent (PED) and 9 per cent (adult). Liver-related mortality was 50 per cent (3/6 deaths) in the PED group with no liver-related deaths in the adult group (27 deaths). Adult patients with blunt liver injury were no more likely to sustain high grade liver injuries than PED patients. Furthermore, adult and PED patients underwent similar rates of operative intervention and primary liver procedures. Adult patients used adjunctive measures as part of their nonoperative management more frequently, but both subsets had similar length of hospital stays and low overall mortality. A higher rate of liver-related mortality was seen in the PED population. Overall, PED patients seemed to sustain fewer liver related complications necessitating invasive procedures despite similar injury patterns.

Laparoscopic Ladd procedure: a minimally invasive approach to malrotation without midgut volvulus.

The management of intestinal malrotation without midgut volvulus is controversial. Some advocate the Ladd procedure in all patients with malrotation, whereas others propose a more selective approach. We attempted the laparoscopic Ladd procedure on nine patients who were diagnosed with intestinal malrotation without volvulus. Patient records were retrospectively reviewed. Data were collected on patient presentation, operative procedure, hospital course, and outcome. The laparoscopic Ladd procedure was successfully completed in eight patients (aged 10 weeks to 25 years). One patient required conversion to an open procedure. Operative time averaged 111 minutes (range, 77-176 minutes). Hospital stay ranged from 3 to 5 days (average, 3.6 days). All patients were discharged home on a regular diet. There was one complication and no deaths. Eight patients had complete resolution of their symptoms. The laparoscopic Ladd procedure is a safe and effective procedure for infants, children, and adults who have intestinal malrotation without midgut volvulus. The operative times, hospital stay, and clinical outcomes were acceptable. We recommend that laparoscopic intervention be considered in patients with intestinal malrotation without volvulus. Intestinal malrotation occurs along a wide spectrum of anatomic variants and clinical presentations. The management of malrotation without midgut volvulus remains controversial. Most advocate performing the Ladd procedure on all patients found to have malrotation because there is no way to know which of these patients will develop catastrophic midgut volvulus. Some propose a more selective approach because of the morbidity associated with operative intervention. There have been a number of small series and case reports describing the use of laparoscopy to diagnose and correct malrotation. Proponents of this method point out its minimally invasiveness, patients' quick recoveries, and successful outcomes. We describe our experience with the laparoscopic Ladd procedure and its long-term results.

Thyroglossal duct and other congenital midline cervical anomalies.

Thyroglossal duct anomalies and dermoid cysts comprise the vast majority of congenital midline cervical masses seen in children. Unusual lesions of the midline neck include ranulae and midline cervical clefts. Workup and management is lesion-dependent, and an accurate preoperative diagnosis is essential for planning and performing an appropriate surgical procedure. This discussion presents an overview of the relevant embryology, pathophysiology, and diagnostic modalities for these congenital midline cervical anomalies. Additionally, the current principles of surgical management are described.

Location of flow limitation in liquid-filled rabbit lungs.

The effects of end-inspiratory lung volume (EILV) and expiratory flow rate (Q) on the location of flow limitation in liquid-filled lungs were investigated by measuring pressure along the airways and by radiographic imaging. The lungs of New Zealand white rabbits were filled with perfluorocarbon to the randomly selected EILV of 20, 30, or 40 ml/kg, and the volume was actively drained at one of three Q: 2.5, 5.0, or 7.5 ml/s. The minimum pressures recorded by a movable catheter at locations along the airways show that flow limitation occurred in the main bronchi and trachea, and was independent of EILV and Q. The minimum pressure at the trachea was -80 mm Hg compared with values that were more positive than -10 mm Hg at a location 3 cm distal to the carina for all EILV and Q combinations. This location was confirmed by the lung images. The airway diameters gradually decreased with time, until flow limitation occurred. In airways distal to the collapse, there was not a significant decrease in diameter. Based on these data, we conclude that flow limitation in liquid-filled lungs occurs in the trachea and main bronchi and its location is independent of EILV or Q.

Perfusion induced hyperthermia for oncologic therapy with cardiac and cerebral protection.

Cancer can be preferentially damaged and killed at temperatures above 41.0 degrees C. However, the heart and brain malfunction at this temperature, limiting the application of systemic hyperthermia in the treatment of metastatic cancer. We created a hyperthermic perfusion system that maximizes the temperature differential produced and extends the safe hyperthermic time. Mongrel dogs were anesthetized and mechanically ventilated. Temperature probes were placed in the rectum, bladder, peritoneal cavity, proximal aorta, pulmonary artery, and right tympanic canal. Venoarterial perfusion was instituted and the perfusate was warmed to 44 to 45 degrees C. The dogs' rectal temperature was elevated to > or = 42 degrees C for 4 hours. A small amount of venous blood was cooled to 28 to 30 degrees C and reperfused into the right atrium to maintain the pulmonary artery temperature < or = 38 degrees C. At the end of the perfusion, the dogs were decannulated, recovered, and returned to their cages for observation. Ten of 11 dogs survived the operative procedure, and no neurologic deficits were observed. The rectal temperature was successfully elevated to > or = 42 degrees C for 4 hours while maintaining the heart and brain at < or = 38 degrees C. Moderate serum biochemical changes were observed postprocedure. However, only the aspartate transaminase and alkaline phosphatase levels remained elevated above both the baseline and canine reference values by day 7. Lower abdominal and pelvic hyperthermia at 42 degrees C can be safely produced and maintained for 4 hours using an extracorporeal perfusion circuit, while protecting the heart and brain from temperature elevation.

Total liquid ventilation: dynamic airway pressure and the development of expiratory flow limitation.

Expiratory flow limitation occurs during total liquid ventilation (TLV), and is characterized by the sudden development of excessively negative intratracheal pressures without increases in flow. The purpose of this study was to identify a dynamic signal for the servoregulation of expiratory flow (Ve), by determining the range of dynamic intratracheal pressures [P(T)], which mark the onset of flow limitation during liquid expiration, where choke occurs at the critical pressure (Pc). The lungs of rabbits were filled with perflurocarbon to an end-inspiratory lung volume (EILV) of 20, 30, or 40cc/kg and connected to a piston driven liquid ventilator, which removed perfluorocarbon at a rate (Vs) of 2.5, 5.0, or 7.5 ml/s. Nine animals per EILV group were used (27 animals total), and within each EILV group each (Vs) was used three times. P(T) and (Ve) (T) were measured at the tracheostomy tube, and dP/dT was calculated from P(T). Pc was determined within each EILV/(Vs) group by examining the average dP/dT curve for the first significant change from baseline. Pc ranged from -6.02 +/- 1.83 to -9.02 +/- 3.2 mm Hg. In general, the higher the EILV, the more negative the Pc. We conclude that Pc during TLV varies within a limited range in rabbits. These data may be used to maximize expired volume during TLV by sequentially tapering flow rates as this critical range of pressures is approached.

A review of 100 patients transported on extracorporeal life support.

Between May 1990 and January 1999, 100 patients (68 adult, 32 pediatric) with severe respiratory or cardiac instability were successfully transported to the University of Michigan Medical Center on extracorporeal life support. Diagnoses included adult respiratory distress syndrome (n = 78), cardiac failure (n = 7), sepsis (n = 7), asthma (n = 5), respiratory distress syndrome (of newborn) (n = 2), and airway compromise (n = 1). Of the patients, 53 were supported with venovenous bypass and 47 with venoarterial bypass. Patients were transported by ground ambulance (n = 80), helicopter (n = 15), or fixed-wing aircraft (n = 5). The median transport distance was 44 miles (range 2-790 miles), and the median transport time was 5 hours and 30 minutes (range: 1 h 33 min to 16 h 6 min). Sixty-six patients (66%) survived to discharge. One death occurred during cannulation, and two patients died before cannulation began. Complications that occurred during transport included 10 cases of electrical failure, 3 cases of circuit tubing leakage, and 1 case each of circuit rupture, membrane lung thrombosis, and membrane lung leakage. None of the complications occurring during transport had an adverse effect on outcome. We conclude that the long distance transport of patients on extracorporeal life support can be safely accomplished and is an effective option for the unstable patient with severe respiratory or cardiac failure.