Coagulation testing in pediatric blunt trauma patients.

OBJECTIVES: To determine the prevalence of abnormal coagulation studies and to identify variables associated with markedly elevated coagulation studies in children with blunt trauma. METHODS: We reviewed the medical records of all patients < 15 years old hospitalized at a Level 1 trauma center for either blunt head or torso trauma over a 4-year period. Data from each patient's emergency department (ED) presentation were abstracted. ED coagulation studies were defined prior to data analysis as elevated if the international normalized ratio (INR) was > or =1.2 or partial thromboplastin time (PTT) was > or =33.0 seconds and markedly elevated if the INR was > or =1.5 or PTT was > or =40 seconds. Variables associated with markedly elevated coagulation studies in a univariate analysis (P < 0.05) were entered into a backward elimination logistic regression analysis to identify variables independently associated with markedly elevated coagulation studies. RESULTS: A total of 1082 patients' records were reviewed, and the 830 (77%) patients with coagulation studies obtained composed the study population. Elevated coagulation studies were detected in 232 (28%) patients, and 49 (6%) of these were found to be markedly elevated. In the multivariate analysis, a GCS < or =13 (odds ratio [OR] 8.7, 95% confidence interval [CI] 4.3, 17.7), low systolic blood pressure (OR 4.0, 95% CI 1.6, 9.9), open/multiple bony fractures (OR 2.9, 95% CI 1.4, 6.2), and major tissue wounds (OR 2.8, 95% CI 1.4, 5.6) were independently associated with markedly elevated coagulation studies. CONCLUSION: Hospitalized pediatric blunt trauma patients frequently have minor elevations in ED coagulation studies. Marked elevations occur infrequently and are independently associated with a GCS < or =13, low systolic blood pressure, open/multiple bony fractures, and major tissue wounds.

Epidemiology of thoracolumbar spine injury in blunt trauma.

OBJECTIVE: To evaluate the prevalence, distribution, and demographics of thoracolumbar (TL) spine injuries following blunt trauma. METHODS: Prospective, cross-sectional study of a consecutive sample of all blunt trauma patients presenting initially to the emergency department (ED) of a Level 1 trauma center and undergoing thoracic and/or lumbar spine radiography from August 1997 to November 1998. The age, sex, and mechanism of injury of each patient as well as location and type of spine injury were recorded for those patients with vertebral fractures, dislocations, or subluxations. RESULTS: Two thousand four hundred four blunt trauma patients were enrolled. Vertebral injuries were identified in 152 individuals (6.3%, 95% CI = 5.4% to 7.4%). Two hundred sixty distinct anatomic levels of injury were identified in these 152 individuals. Of these 260 injuries, 42 (16.2%) occurred at L1, 38 (14.6%) at L2, 29 (11.1%) at L3, and 27 (10.4%) at T12, making these the most commonly injured vertebrae. Injuries were most common (34 patients) in those aged 30-39 years and were least common (12 patients) in those under 18 years. Compression fractures (52%) were the most common injury in the thoracic spine, while transverse process fractures (48%) were the most common injuries in the lumbar spine. CONCLUSIONS: The prevalence of TL injuries in ED blunt trauma patients undergoing TL radiographs is 6.3%. The most commonly injured area of the TL spine is the thoracolumbar junction.

Gastric rupture and massive pneumoperitoneum after bystander cardiopulmonary resuscitation.

Gastric perforation is a rare complication of cardiopulmonary resuscitation. The majority of reported cases have been associated with difficult airway management or esophageal intubation. There has been only one previous case report in which this complication could be attributed solely to mouth-to-mouth ventilation. We present a case of simple bystander cardiopulmonary resuscitation that resulted in gastric perforation.

Emergency department ultrasonography in the evaluation of hypotensive and normotensive children with blunt abdominal trauma.

PURPOSE: The aim of this study was to evaluate the accuracy of emergency department (ED) ultrasound scan in identifying which children with blunt torso trauma have intraperitoneal fluid associated with intraabdominal injuries (IAI). METHODS: The authors conducted a prospective, observational study of children (< 16 years old) with blunt trauma who presented to a level 1 trauma center over a 29-month period and underwent abdominal ultrasound scan while in the ED. Ultrasound examinations were ordered at the discretion of the trauma surgeons or ED physicians caring for the patients, performed by trained sonographers, and interpreted at the time of the ultrasound. Ultrasound examinations were interpreted solely for the presence or absence of intraperitoneal fluid. Hypotension was defined as > or = 1 standard deviation below the age-adjusted mean. Patients underwent follow-up to identify those with intraperitoneal fluid and IAI. RESULTS: A total of 224 pediatric blunt trauma patients had ultrasound scan performed and were enrolled. Thirty-three patients had IAI with intraperitoneal fluid, and ultrasound scan was positive in 27. The accuracy of abdominal ultrasound for detecting intraperitoneal fluid associated with IAI was sensitivity, 82% (95% confidence interval [CI] 65% to 93%); specificity, 95% (95% CI 91% to 97%); positive predictive value, 73% (95% CI 56% to 86%); and negative predictive value, 97% (95% CI 93% to 99%). In the 13 patients who were hypotensive, ultrasound scan correctly identified intraperitoneal fluid in all 7 patients (sensitivity 100%) with IAI, and hemoperitoneum and was negative in all 6 patients (specificity 100%) who did not have hemoperitoneum. Nine patients had IAI without intraperitoneal fluid, and ultrasound scan result was negative for fluid in all 9. CONCLUSIONS: ED abdominal ultrasound scan used solely for the detection of intraperitoneal fluid in pediatric blunt trauma patients has a modest accuracy. Ultrasonography has the best test performance in those children who are hypotensive and should be obtained early in the ED evaluation of these patients.

Test performance of the individual NEXUS low-risk clinical screening criteria for cervical spine injury.

BACKGROUND: The National Emergency X-Radiography Utilization Study (NEXUS) recently validated the ability of a decision instrument to define a population with an extremely low risk of cervical spine injury (CSI) after blunt trauma. It is unclear whether each of the 5 individual criteria is necessary for the decision instrument to maintain its high sensitivity. METHODS: NEXUS was a prospective observational study at 21 emergency departments, which enrolled all patients with blunt trauma for whom cervical spine radiographs were ordered. In this substudy, we examined the NEXUS database to determine the contribution of each of the 5 individual low-risk clinical criteria to the overall sensitivity of the decision instrument. RESULTS: All but 8 of 818 patients with CSI, and all but 2 of 578 patients with significant CSI, were identified by using the decision instrument. A substantial number of patients with CSI (236/818 [29%]) and patients with significant CSI (175/578 [30%]) met only 1 of the 5 non--low-risk criteria, and each of the 5 criteria was the only indicator of non--low-risk status in at least 8 patients with CSI and at least 5 patients with significant CSI. CONCLUSION: Because each of the 5 low-risk criteria was the only marker of non--low-risk status in at least a few patients with significant CSI, modification of the overall NEXUS decision instrument by eliminating any one of the criteria would markedly reduce sensitivity and make the instrument unacceptable for clinical use.

Abdominal ultrasound examination in pregnant blunt trauma patients.

BACKGROUND: The ability of abdominal ultrasound to detect intraperitoneal fluid in the pregnant trauma patient has been questioned. METHODS: Pregnant blunt trauma patients admitted to a Level I trauma center during an 8-year period were reviewed. Ultrasound examinations were used to detect intraperitoneal fluid and considered positive if such fluid was identified. RESULTS: One hundred twenty-seven (61%) of 208 pregnant patients had abdominal ultrasound during initial evaluation in the emergency department. Seven patients had intra-abdominal injuries, and six had documented hemoperitoneum. Ultrasound identified intraperitoneal fluid in five of these six patients (sensitivity, 83%; 95% confidence interval, 36-100%). In the 120 patients without intra-abdominal injury, ultrasound was negative in 117 (specificity, 98%; 95% confidence interval, 93-100%). The three patients without intra-abdominal injury but with a positive ultrasound had the following: serous intraperitoneal fluid and no injuries at laparotomy (one) and uneventful clinical courses of observation (two). CONCLUSION: The sensitivity and specificity of abdominal ultrasonography in pregnant trauma patients is similar to that seen in nonpregnant patients. Occasional false negatives occur and a negative initial examination should not be used as conclusive evidence that intra-abdominal injury is not present. Ultrasound has the advantages of no radiation exposure.

Prevalence and importance of pneumothoraces visualized on abdominal computed tomographic scan in children with blunt trauma.

BACKGROUND: Chest radiographs are routinely obtained for the identification of pneumothoraces in trauma patients. Computed tomographic (CT) scanning has a higher sensitivity for the detection of pneumothoraces, but the prevalence and importance of pneumothoraces detectable by CT scan but not by chest radiography in children sustaining blunt trauma is unclear. METHODS: We conducted a prospective observational cohort study of children less than 16 years old with blunt trauma undergoing both abdominal CT scan and chest radiography in the emergency department of a Level I trauma center over a 28-month period. All abdominal CT scans were interpreted by a single faculty radiologist. The chest radiographs of all patients with pneumothoraces detected on CT scan as well as a random sample of chest radiographs from pediatric blunt trauma patients without pneumothoraces on abdominal CT scan (in a ratio of four normals per pneumothorax) were reviewed by a second faculty radiologist. Both radiologists were masked to all clinical data as well as to the objective of the study. RESULTS: Five hundred thirty-eight children underwent both abdominal CT scan and chest radiography in the emergency department. Twenty patients (3.7%; 95% confidence interval [CI], 2.3-5.7%) were found to have pneumothoraces on CT scan. Of these 20 patients, 9 (45%; 95% CI, 23-68%) had pneumothoraces identified on initial chest radiography and 11 patients did not ("unsuspected pneumothoraces"). Twelve pneumothoraces were identified in these 11 patients; 6 were graded as minuscule and 6 as anterior according to a previously established scale. One patient with an unsuspected pneumothorax underwent tube thoracostomy. None of the 10 patients (0%; 95% CI, 0-26%) with unsuspected pneumothoraces who were managed without thoracostomy (including two patients who underwent positive pressure ventilation) had complications from their pneumothoraces. CONCLUSION: Less than half of pediatric blunt trauma patients with pneumothoraces visualized on abdominal CT scan had these pneumothoraces identified on initial chest radiograph. Patients with pneumothoraces identified solely on abdominal CT scan, however, uncommonly require tube thoracostomy.

Isolated intraperitoneal fluid on abdominal computed tomography in children with blunt trauma.

OBJECTIVE: To determine the frequency of isolated intraperitoneal fluid (IIF) on abdominal computed tomography (CT) in pediatric blunt trauma patients and the association between IIF and clinically identifiable intra-abdominal injuries (IAIs) in these patients. METHODS: The authors conducted a prospective observational study of consecutive children <16 years old with blunt torso trauma who underwent abdominal CT scanning while in the emergency department (ED). All patients were evaluated by a faculty emergency physician who documented the patient's physical examination. All CTs were interpreted by a single faculty radiologist masked to clinical data. The volume of intraperitoneal fluid was quantified (small, moderate, large) and the presence of organ injury visible on CT was noted. Patients were considered to have IIF if the CT demonstrated intraperitoneal fluid and no solid organ injury. Patients with IIF were followed through their hospitalizations or telephoned in one week if discharged home from the ED. RESULTS: Five hundred twenty-seven children with blunt trauma were enrolled into the study. The mean age (+/-SD) was 7.4 +/- 4.7 years, and the median pediatric trauma score was 10 (range -2 to 12). Eighty-eight patients (17%; 95% CI = 14% to 20%) had intraperitoneal fluid on CT scan and 42 (48%; 95% CI = 37% to 59%) of these patients had IIF. Of the 42 patients with IIF, five patients (all without abdominal tenderness and with a small amount of IIF on CT scan) were discharged to home from the ED and were well at telephone follow-up; the remaining 37 patients were hospitalized. Of the 42 patients with IIF, 7 patients (17%, 95% CI = 7 to 31%) had IAIs subsequently identified (all gastrointestinal injuries) during their evaluations. Six of the seven patients with IIF and subsequently identified IAIs had abdominal tenderness on examination in the ED. The remaining patient had a decreased level of consciousness. CONCLUSIONS: Isolated intraperitoneal fluid occurs in 8% of pediatric blunt trauma patients undergoing abdominal CT, and IAIs are subsequently identified in 17% of these patients. Patients with a small amount of IIF on CT who lack abdominal tenderness and have a normal level of consciousness are at low risk for subsequently identified IAIs.

Pulmonary arterial fibromuscular dysplasia: a rare cause of fulminant lung hemorrhage.

Arterial fibromuscular dysplasia (FMD) represents a collection of noninflammatory and nonatherosclerotic vascular diseases with a poorly understood etiology. Classically occurring in renal and cerebral arteries, this entity has also been reported in coronary, carotid, and other medium and small arteries. One case occurring in the pulmonary vasculature has been reported. Fatal hemothorax and lung hemorrhage have multiple causes, including other vascular malformations and connective tissue disorders; however, cases of pulmonary FMD are exceedingly rare. We report what appears to be the second such association, occurring in a 69-year-old man. The patient presented with a 3-week history of increasing dyspnea, fatigue, and productive cough; 3 days of increasing back and chest pain; and syncope. Chest radiograph showed a "white-out" of the left lung. The patient died shortly after admission from a fulminant respiratory disease of undetermined etiology. At autopsy he was found to have a massive left hemothorax resulting from an unsuspected pulmonary arterial fibromuscular dysplasia.

Identification of intra-abdominal injuries in children hospitalized following blunt torso trauma.

OBJECTIVE: To determine the utility of the ED physical examination and laboratory analysis in screening hospitalized pediatric blunt trauma patients for intra-abdominal injuries (IAIs). METHODS: The authors reviewed the records of all patients aged <15 years who sustained blunt traumatic injury and were admitted to a Level 1 trauma center over a four-year period. Patients were considered high-risk for IAI if they had any of the following at ED presentation: decreased level of consciousness (GCS < 15), abdominal pain, tenderness on abdominal examination, or gross hematuria. Patients without any of these findings were considered moderate risk for LAI. The authors compared moderate-risk patients with and without IAIs with regard to physical examination and laboratory findings obtained in the ED. RESULTS: Of 1,040 children with blunt trauma, 559 (54%) were high-risk and 481 (46%) were moderate-risk for IAI. 126 (23%) of the high-risk and 22 (4.6%) of the moderate-risk patients had IAIs. Among moderate-risk patients with and without IAIs, those with IAIs were more likely to have abdominal abrasions (5/22 vs 34/459, p = 0.008), an abnormal chest examination (11/22 vs 86/457, p = 0.01), higher mean serum concentrations of aspartate aminotransferase (AST) (604 U/L vs 77 U/L, p < 0.001) and alanine aminotransferase (ALT) (276 U/L vs 39 U/L, p = 0.002), higher mean white blood cell (WBC) counts (16.3 K/mm3 vs 12.8 K/mm3, p < 0.001), and a higher prevalence of >5 RBCs/hpf on urinalysis (7/22 vs 54/427, p = 0.02). There was no significant difference (p > 0.05) between moderate-risk patients with and without IAIs in initial serum concentrations of amylase, initial hematocrit, drop in hematocrit >5 percentage points in the ED, or initial serum bicarbonate concentrations. CONCLUSION: In children hospitalized for blunt torso trauma who are at moderate risk for IAI, ED findings of abdominal abrasions, an abnormal chest examination, and microscopic hematuria as well as elevated levels of AST and ALT, and elevated WBC count are associated with IAI.

Comparison of 2 cricothyrotomy techniques: standard method versus rapid 4-step technique.

STUDY OBJECTIVE: To compare the success rate, complication rate and time required for the rapid 4-step technique versus the standard technique for cricothyrotomy. METHODS: We conducted a prospective, randomized crossover study. Twenty-seven emergency medicine interns, 1 junior medicine resident, and 4 senior medical students, without prior cricothyrotomy experience, were randomly divided into 2 groups. Group 1 was initially instructed in and then performed the standard technique; group 2 was initially instructed in and then performed the rapid 4-step technique. Each group was then instructed in and performed the alternate method. Cricothyrotomies were performed on preserved human cadavers. RESULTS: A surgical airway was established in 28 of 32 attempts with the use of the rapid 4-step technique (88%); the average time elapsed before tube placement was 43 seconds. Thirty of 32 attempts involving the standard technique (94%) were successful; the average time to tube placement was 134 seconds (95% confidence interval for a difference of 91 seconds, 63 to 119; P < .001). Complications were identified in 12 attempts involving the standard technique (38%; 1 considered major) and in 12 involving the rapid four-step technique (38%; 3 considered major). The incidence of major complications was 6% higher for the rapid 4-step technique (95% confidence interval, -9% to 21%). CONCLUSION: In a group of inexperienced subjects working on a preserved human cadaver model, the rapid 4-step technique for cricothyrotomy was performed in about one third the time required for performance of the standard technique. This finding was both clinically and statistically significant. Although the 2 techniques had similar success and complication rates, we noted a trend toward more severe complications in the rapid 4-step technique.

Failure of the Miller criteria to predict significant intracranial injury in patients with a Glasgow Coma Scale score of 14 after minor head trauma.

OBJECTIVE: To determine the utility of the Miller criteria (presence of headache, nausea, vomiting, and signs of depressed skull fracture) for predicting the need for CT in patients with minor head trauma and a Glasgow Coma Scale score (GCS) of 14. METHODS: The study was a prospective, consecutive series of all patients undergoing head CT scans with a GCS of 14 following head trauma. A data sheet was completed for all patients prior to obtaining a head CT scan. RESULTS: 264 patients were entered into the study and 35 patients were found to have traumatic abnormalities on head CT scan. The use of the Miller criteria to select those patients who would require head CT scan would have resulted in missing 17 of the 35 abnormal scans, including 2 patients who required neurosurgical intervention. These 2 patients were markedly intoxicated upon presentation. CONCLUSION: The use of the Miller criteria as the only criteria for screening patients with a GCS of 14 after minor head trauma who require a head CT scan is not recommended. While the authors have identified ethanol intoxication as one confounding factor, further refinement of this risk-stratification tool is required.

Utilizing clinical factors to reduce head CT scan ordering for minor head trauma patients.

Our study objective was to determine whether simple clinical criteria can be used to safely reduce the number of patients who require cranial computed tomography (CT) scan after sustaining minor head trauma. Awake patients (Glascow Coma Scale = 15) who presented to the emergency department with acute head injury associated with a loss of consciousness were evaluated for clinical predictors of head injury prior to CT scan. The studied risk factors included severe headache, nausea, vomiting, and depressed skull fracture on physical examination. Patients with no risk factors present were compared with patients with one or more risk factors with respect to abnormal CT rate and rate of operative intervention for head injury. Of the 2143 patients entered into the study, 1302 (61%) had no risk factor for head injury, whereas 841 (39%) had one or more risk factors present. A total of 138 (6.4%) of those studied had an abnormal CT scan. This number included 3.7% of those patients with no risk factors vs. 11% in patients with one or more risk factors. The CT scan abnormalities in the no-risk-factor group were not clinically significant. All 5 patients who required operative intervention had at least one of the risk factors present. The use of four simple clinical criteria in minor head trauma patients would allow a 61% reduction in the number of head CT scans performed and still identify all patients who require neurosurgical intervention and the majority of patients with an abnormal CT scan. This method could lead to a large savings in patient charges nationwide. Further studies may be helpful in confirming these findings.

Optimum optical local-oscillator power levels for coherent detection with photodiodes.

The use of an optical local oscillator for coherent detection with a photodiode can significantly reduce the responsivity of the detector because of saturation effects. Consequently, local-oscillator shot-noise-limited operation of the detector may not be possible. This effect is analyzed and formulations are developed for the optimum optical local-oscillator power level and the resultant maximum possible signal-to-noise ratio in terms of parameters derived from the photodiode current versus the optical power response curve. An effective heterodyne responsivity that can be used as a part of the specifications when one is procuring photodiodes for use in coherent detection systems is defined.

Optical remote sensing of surface roughness through the turbulent atmosphere.

Using a CO(2), cw, coherent lidar, we have measured the surface roughness of diffuse targets through 1000 m of turbulent atmosphere. The technique measures the phase fluctuations of the speckle field at the receiver and relates the measured phase variance to the surface roughness. Measurements were made with aluminum targets that had been sandblasted with 8-, 16-, and 30-grit material and also with a flame-sprayed aluminum target. It was found that a linear relationship exists between the standard deviation (SD) of the unwrapped phase fluctuations and the SD of the target surface-height fluctuations. Good results were obtained with modest transmitter power and small receiver optics in just a few seconds of averaging time.

Optical propagation and scattering related to the atmosphere, dense volume media, and rough surfaces: an introduction by the feature editors.

This issue of Applied Optics features 27 papers on topics related to optical propagation and scattering in the atmosphere and dense volume media and scattering from rough surfaces. The papers in this special issue are derived from presentations at the International Commission for Optics Topical Meeting onAtmospheric, Volume, and Surface Scattering and Propagation held in Florence, Italy, on 27-30 August 1991 as well as from other contributed papers on the subject areas covered by the meeting.

Covariance of the received intensity of a partially coherent laser speckle pattern in the turbulent atmosphere.

A theoretical expression for the covariance of the received intensity of a partially coherent laser speckle pattern after propagation through the turbulent atmosphere is developed. It is shown that the atmospheric perturbation on a partially coherent speckle pattern can be decomposed into a coherent term and an incoherent term. The dependence of contributions of these components on the level of turbulence, vacuum speckle-contrast ratio, and detector spacing is studied in detail and the results are compared with the available experimental data.

Unwrapped-phase distribution model for speckle and turbulence.

A model for the unwrapped phase of a speckle field that propagates through clear air turbulence is proposed, and a formulation for the probability density function of the unwrapped phase is developed. A method is given to obtain the parameters of the unwrapped density function from parameters of the diffuse target, the laser source, and the atmosphere. Unwrapped-phase measurements at an atmospheric test site with a CO(2) laser show agreement with the model.