Feasibility of using interpolated contours of targets and organs at risk in intensity-modulated radiation therapy treatment planning for advanced-stage nasopharyngeal carcinoma

To assess the dosimetric effect of using interpolated contours in planning intensity-modulated radiation therapy (IMRT) for advanced T-stage nasopharyngeal carcinoma. The present study focused on T3-T4 tumours where the proximity of targets to neurological organs poses a stringent test on the feasibility of such an approach. Contours of targets and organs were delineated on CT images of 2.5-mm interval and a reference IMRT plan was generated. An investigative (INV) IMRT plan was then generated with the same planning protocol, but based on interpolated contours that replaced deleted contours on alternate slices. The reference and INV plans were compared. Regarding target coverage, all targets in the INV plans met the acceptance criteria except for the PTV in one case. Regarding organs, the mean dose to 1% volume of the brainstem and spinal cord in the INV plans were kept below their dose limits. No significant differences in the mean doses to others organs were found. Satisfactory target coverage and protection of critical organs to a degree similar to full-scale contouring could be achieved with use of interpolated contours. The saving in manpower time for contouring is expected to significantly improve the throughput of the IMRT planning process.

Development of a rapid method for determining the infectious dose (ID)50 of Orientia tsutsugamushi in a scrub typhus mouse model for the evaluation of vaccine candidates

The infectious dose (ID) of an inoculum for which 50% of susceptible mice will become infected (ID(50)) with Orientia tsutsugamushi is usually determined by rechallenging mice that have already been challenged with O. tsutsugamushi to determine the lethal dose (LD)(50) titer of the inoculum. Those mice not killed by the initial challenge and which survived a rechallenge with 1000 LD(50) were considered immune and to have been initially infected with O. tsutsugamushi. Mice that succumbed to the rechallenge were considered not to have been initially infected. We have developed a more rapid method of determining the ID(50) of inocula for use in our vaccine studies based upon the observation that mice surviving initial challenge and that go on to survive rechallenge produced detectable IgG to O. tsutsugamushi antigens by enzyme-linked immunosorbent assay (ELISA). Mice that did not survive rechallenge, and therefore did not receive an initial infectious inoculum did not produce detectable IgG to O. tsutsugamushi antigens. Both original LD(50) and ID(50) titers determinations require observation of mice for 21 days post-challenge. Our new ID(50) determination does not require mice or the additional 21-day observation period for rechallenge and therefore is more rapid and cost-effective than the previous standard method of determining ID(50) titer necessary for the evaluation of vaccine candidates.

Review of prehospital sodium bicarbonate use for cyclic antidepressant overdose

OBJECTIVE

To describe the clinical presentation of patients with cyclic antidepressant (CA) and use of sodium bicarbonate (NaHCO(3)) in the treatment of this overdose in the prehospital setting.

METHODS

A three year retrospective observational review of records was performed using the San Diego County Quality Assurance Network database for prehospital providers. All adult patients who were treated with NaHCO(3) by paramedics for a CA overdose were included. Demographic data, presenting cardiovascular and neurological symptoms, paramedic treatments, and any changes in status were reviewed.

RESULTS

Twenty one patients were treated by paramedics with NaHCO(3) for CA overdose. Seventeen patients (80%) presented with mental status changes, including 11 presenting with a GCS<8. Seven of the 21 (33%) presented with a cardiac arrhythmia expected to possibly respond to NaHCO(3) treatment. Seven of the 21 (33%) were hypotensive, and five (24%) patients had reported seizure activity. Only 2 of the 21 patients (10%) treated with NaHCO(3) had recorded improvements after administration of the drug, while the other 19 remained stable without any deterioration. Sixteen of 21 patients (76%) were given NaHCO(3) for indications on standing order, while five patients were treated outside the standing order indications by base physician order with none of the five patients having any change in status ater treatment.

CONCLUSIONS

After prehospital NaHCO(3) use in patients with CA overdose, there were no complications reported, two patients improved in status and the others remained unchanged. Base hospital physician orders of NaHCO(3) for indications beyond the standing orders were not associated with changes in patient status.

Steric effects on diffusion of associated molecules in acetone

The effects due to steric hindrance on solute-solvent interactions and on diffusion of associated molecules were found by comparing the diffusion coefficients of different aromatic isomers in acetone at 298.2 K; there exists a correlation between the isomeric effects of intermolecular association on diffusion and the molecular scales of overall hydrogen-bond acidity of the isomers studied.

The hemispheric difference of semantic processing of Chinese characters in two dimensions as revealed by ERPs

An experiment was conducted to examine the hemispheric dominance in semantic processing of Chinese characters. Results showed that N1 is the earliest component that reflects the semantic processing of Chinese characters. Although N1 of the left hemisphere is larger in amplitude, that of the right hemisphere is shorter in latency. Based on these findings, the authors propose that the left hemisphere does not start processing until the necessary information has been transferred from the right hemisphere. Once the left hemisphere starts processing, its intensity is stronger. Thus, it is more appropriate to differentiate hemispheric processing dominance into two dimensions: speed and intensity. Moreover, the semantic cognition onset of Chinese characters occurs from 100 ms to 160 ms in the posterior perceptual processing area of brain.

Electrocardiographic manifestations: pulmonary embolism

The electrocardiographic findings associated with pulmonary embolism have been well described in the medical literature for over 50 years. These abnormalities include changes in rhythm, QRS axis, and morphology, particularly in the QRS and T waves. Such findings may reflect hemodynamic changes, such as right heart strain, as well as myocardial ischemia associated with the disease. Although certain findings may correlate with the severity of pulmonary embolism, the overall utility of the electrocardiogram is limited due to the variable presence, frequency, and transient nature of most of the abnormalities associated with the disease.

Severe traumatic brain injury from unmotorized scooter

The popularity and use of unmotorized, foot-propelled scooters has risen dramatically in the last few years. Increasing reports of traumatic injuries from these scooters have paralleled their commercial sales and success in this country and worldwide. We report a case of a previously healthy 48-year-old woman who suffered a severe traumatic brain injury while riding one of these scooters, resulting in a devastating neurologic outcome and permanent vegetative state. This case emphasizes the importance of public awareness regarding the potential dangers and the need for appropriate precautions and protective gear when riding these recreational devices.

Estimation of pediatric patient weight by EMT-PS

To determine paramedics' experience, comfort, and accuracy in the estimation of pediatric weights, paramedics were surveyed regarding their experience and training in estimating pediatric weights and then were presented with four children and asked to estimate their weights and to calculate the first round of i.v. epinephrine dose for asystole according to protocol. Twenty paramedics participated, with 55% stating they were uncomfortable on pediatric calls; 15 of 20 (75%) stated they were uncomfortable estimating children's weights. The majority of estimations were within 50% of the actual weights. Based on weight estimations, the epinephrine doses were calculated correctly in 88% of all cases. In 10% of cases, the epinephrine dose was incorrect by a factor of 10 times the appropriate dose. The weight range using the Broselow tape was determined correctly by all participants, with 95% correctly reporting the correct dose of epinephrine. Overall, paramedics were accurate in estimating pediatric weights, and use of the Broselow tape improved the precision of these estimations.

The prehospital electrocardiogram

Although widely used in Europe, the prehospital 12-lead electrocardiogram (EKG) has seen only limited use in this country. Reported benefits of the 12-lead EKG include shortening the door-to-needle time, accelerating the initiation of reperfusion therapy, and overall improving the prehospital and hospital management and outcome of patients with acute myocardial infarction. The field EKG also provides the basis for prehospital fibrinolysis. Concerns still exist, however, regarding the best means of providing real-time field interpretation of the prehospital EKG and the potential for inappropriate field time delay, triage, and treatment of patients. Moreover, questions remain about the overall clinical and cost benefit of expanding this resource universally. The following article reviews the role of prehospital EKG in caring for patients with acute coronary syndromes.

Outcome study of minors after parental refusal of paramedic transport

OBJECTIVE

Patient refusal of paramedic transport against medical advice (AMA) has significant medical-legal implications. Previous studies have investigated patient outcomes after refusal of transport, but none has focused on these events in minors. This study was performed to evaluate the outcomes of this patient population after refusal of transport as well as the significance of base hospital physician discussion with parents in the decision to refuse transport.

METHODS

This was a retrospective telephone follow-up survey involving parents of minors for whom transport was refused after accessing emergency medical services (EMS) via the 911 system. Data were initially obtained from paramedic run records and each family was subsequently contacted by telephone and surveyed with regard to their experiences with the field medics in addition to the medical follow-up sought for their child and patient outcomes.

RESULTS

Eighty-nine patients met criteria for survey. Telephone contact was made with 44 parents, of whom 32 (73% of those contacted, 36% overall) participated. Twenty-seven (84%) received medical follow-up, either at an emergency department or in a private physician's office. Most patients (89%) who were evaluated and/or treated by a physician were subsequently released, while three children were admitted to the hospital, all three with respiratory or cardiac chief complaints.

CONCLUSIONS

Children whose parents refused EMS transport received medical follow-up in the majority of cases, with a small group requiring admission.

Electrocardiographic manifestations: Acute posterior wall myocardial infarction

Posterior myocardial infarction (PMI) refers to infarction of the posterior wall of the left ventricle. Although often associated with inferior and lateral myocardial infarctions, detection of acute PMI is difficult because the standard 12-lead electrocardiogram does not adequately image the posterior wall of the left ventricle. We review the findings on 12-lead electrocardiogram with PMI, as well as discuss the utility of additional electrocardiographic leads in the diagnosis of PMI.

Electrocardiographic manifestations: digitalis toxicity

Toxicity from the digitalis family of cardiac glycoside medications remains common. Successful treatment depends on early recognition; however, the diagnosis of potentially life-threatening toxicity remains difficult because the clinical presentation is often nonspecific and subtle. The hallmark of cardiac toxicity is increased automaticity coupled with concomitant conduction delay. Though no single dysrhythmia is always present, certain aberrations such as frequent premature ventricular beats, bradydysrhythmias, paroxysmal atrial tachycardia with block, junctional tachycardia, and bidirectional ventricular tachycardia are common. Treatment depends on the clinical condition rather than serum drug level. Management varies from temporary withdrawal of the medication to administration of digoxin-specific Fab fragments for life-threatening cardiovascular compromise.

A role for Xlim-1 in pronephros development in Xenopus laevis

Xlim-1, a LIM class homeobox gene expressed in Xenopus laevis, is one of the earliest known marker genes of pronephros development and is expressed in pronephros rudiment. In this study, we examined the role of Xlim-1 in pronephros development. Temporal expression of Xlim-1 in explants was analyzed in a series of induction assays using RT-PCR analysis. Xlim-1 was expressed 9 to 15 h after activin/retinoic acid treatment, corresponding to pronephros differentiation in explants. We further examined the role of Xlim-1 using a series of microinjection experiments. Presumptive pronephric anlagen of embryos were injected with various Xlim-1 mutants, and effects of these Xlim-1 mutants on pronephrogenesis in embryos and in explants were analyzed by RT-PCR and immunohistochemistry. Dominant-negative Xlim-1 inhibited differentiation of pronephros in activin/retinoic acid-treated animal caps. In embryos injected with a dominant-negative form of Xlim-1, development of pronephric tubules was inhibited at the late tail-bud stage. Our results suggest that Xlim-1 may not initiate differentiation of the pronephros, but that it is necessary for growth and elongation in the development of pronephric tubules.

Electrocardiographic manifestations: aberrant ventricular conduction

Aberrant ventricular conduction is a common electrocardiographic (EKG) manifestation that occurs when the supraventricular electrical impulse is conducted abnormally through the ventricular conducting system. This results in a wide QRS complex that may be confused with a ventricular ectopic beat. This differentiation is important because the treatment and prognosis is quite different. Hemodynamically unstable patients with a wide-complex tachycardia should be promptly cardioverted. Although up to 10% of cases will defy differentiation, ventricular tachycardia and aberrant conduction can be distinguished utilizing history, physical examination, and EKG criteria. The mechanisms of aberrant ventricular conduction are discussed.

Emergency department patient knowledge of medications

Therapeutic decisions made by Emergency Physicians are often influenced by which prescribed medications are being taken by patients. We sought to assess Emergency Department (ED) patients' knowledge of their medications by using a survey. A convenience sample of adult ED patients was surveyed verbally by a research assistant. Two-hundred patients were enrolled. Only 48% of patients could recall or produce a list or the actual bottles of all of their medications, 39% knew the times they take their medications, and only 24% knew all the dosages. Seventeen percent brought a list or the actual medication bottles with them to the ED. Patients who had a primary care physician knew all their medications 51% of the time, compared to 43% who did not have a physician. Fifty-one percent of insured patients compared to 38% of non-insured patients could identify all of their medications. Although knowledge of medications is often critical for decision making in the ED, a significant number of patients are unable to provide this information.

Successful prehospital airway management by EMT-Ds using the combitube

OBJECTIVE

To evaluate the ability to train emergency medical technicians-defibrillation (EMT-Ds) to effectively use the Combitube for intubations in the prehospital environment.

METHODS

This was an 18-month prospective field study in which EMT-Ds were trained how and in what situations to use the Combitube. Data were then obtained for all patients in whom Combitube insertion was attempted. Indications for use of the Combitube included: unconsciousness without a purposeful response, absence of the gag reflex, apnea or respiratory rate less than 6 breaths/min, age more than 16 years, and height at least 5 feet tall. Contraindications were: obvious signs of death, intact gag reflex, inability to advance the device due to resistance, or known esophageal pathology. Data were entered prospectively from the San Diego County EMS QANet database for prehospital providers.

RESULTS

Twenty-two EMT-D provider agencies, involving approximately 500 EMT-Ds, were included as study participants. Combitube insertions were attempted in 195 prehospital patients in cardiorespiratory arrest, with appropriate indication for Combitube use. An overall successful intubation rate (defined as the ability to successfully ventilate) of 79% was observed. Identical success rates for medical and trauma patients were noted. The device was placed in the esophagus 91% of the time. Resistance during insertion was the major reason for unsuccessful Combitube intubations. An overall hospital admission rate of 19% was observed. No complications were reported.

CONCLUSION

EMT-Ds can be trained to use the Combitube as a means of establishing an airway in the prehospital setting. Future studies will need to further evaluate its effect on patient outcome.

Rapid sequence intubation in the field versus hospital in trauma patients

We conducted a retrospective review of all adult trauma patients who underwent prehospital field rapid sequence intubation (RSI) by aeromedical crews from 1988 through 1995 and compared them to all trauma patients who arrived by ground transportation and underwent RSI in the trauma suite from 1992 through 1995 at a University hospital. Of the 47 field RSI patients, 46 (97.9%) were successfully intubated, whereas 263 of the 267 (98.5%) hospital RSI patients were successfully intubated. There were no statistical differences in success rates, number of attempts, or immediate intubation events in the procedure between the two groups. There were no differences in delayed events with the exception of pneumonia, which occurred more frequently in the field RSI group (28% vs. 6%, respectively). We performed a subgroup analysis on isolated head injury patients to evaluate outcome. There was no difference in total hospital days, length of ICU stay, mortality or final disposition in the two head injury groups. Though this study is limited by small sample size, we conclude that field RSI is equally successful and safe as hospital RSI.

Safety and efficacy of the Rapid Four-Step Technique for cricothyrotomy using a Bair Claw

The Rapid Four-Step Technique (RFST) has been demonstrated to be faster than standard open crico thyrotomy technique, but may have a higher incidence of cricoid injury with tracheal hook traction applied caudad. The "Bair Claw" is a novel device that may help eliminate these complications. This randomized, experimental trial used a fresh-frozen cadaver model of cricothyrotomy to compare speed and safety between RFST using a Bair Claw and standard open technique. Outcome measures included time to definitive airway, size of largest endotracheal (ET) tube able to be passed, and incidence of complications. We observed that RFST using a Bair Claw was significantly faster than standard open technique. There was no significant difference with regard to size of ET tube able to be passed with RFST using a Bair Claw versus standard open technique, and there was no damage to trachea or larynx observed with either technique. We concluded that RFST using a Bair Claw is faster and appears to be equally safe when compared to standard open technique in a fresh-frozen cadaver model of cricothyrotomy. The two techniques were equal with regard to maximal ET tube size.

Spirometry in normal subjects in sitting, prone, and supine positions

OBJECTIVE

Determine whether pulmonary function testing is affected by patient positioning.

METHODS

In a descriptive study with measurements made in a sequential but randomized order at a university-based pulmonary function laboratory, 20 healthy men, ages 18-50 years, were evaluated with spirometric assessment of forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and maximum voluntary ventilation (MVV) in the sitting, supine, and prone positions. Subjects were excluded for body mass index (BMI) > 30 kg/m2 or abnormal baseline spirometry.

RESULTS

Comparing sitting to supine and prone positions, there was a statistically significant decline in the spirometry values (reported as percent of predicted normal +/- standard error of the mean). FVC was 102% +/- 4% while sitting, 95% +/- 4% while supine, and 94% +/- 4% while prone. FEV1 was 104% +/- 3% while sitting, 96% +/- 3% while supine, and 94% +/- 3% while prone. MVV was 115% +/- 4% while sitting, 102% +/- 4% while supine, and 97% +/- 3% prone.

CONCLUSION

In healthy men with BMI < 30 kg/m2, changing from the sitting to supine or prone position results in statistically significant change in respiratory pattern. However, all spirometry values in each position were normal by American Thoracic Society definitions.

Use of a complete neurological examination to screen for significant intracranial abnormalities in minor head injury

Indications for head computed tomography (CT) scans are unclear in patients with nonpenetrating head injury and Glasgow Coma Scale (GCS) scores of 15. We performed a prospective study to determine if significant intracranial injury could be excluded in patients with GCS-15 and a normal complete neurological examination. A prospective trial of clinically sober adult patients with GCS = 15 on emergency department (ED) presentation after closed head injury with loss of consciousness or amnesia was conducted from May 1996 through April 1997. All subjects underwent a standardized neurological examination including mental status evaluation, and assessment of motor, sensory, cerebellar and reflex function before CT scan. During the study period, 58 patients met inclusion criteria. Fifty-five patients (95%) had normal CT scans and 23 (42%) had focal neurological abnormalities. Three patients (5%) had CT scan findings of acute intracranial injury, two of whom had normal neurological examinations. One patient had an acute subdural hematoma requiring emergent surgical decompression; the other had both an epidural hematoma and pneumocephalus that did not require surgery. Significant brain injury and need for CT scanning cannot be excluded in patients with minor head injury despite a GCS = 15 and normal complete neurological examination on presentation.

Longitudinal colour doppler study of superficial lymph nodes in non-Hodgkin's lymphoma patients on chemotherapy

AIMS/METHODS

A longitudinal study of 22 malignant lymph nodes by colour Doppler (CD) and/or colour power (CP) ultrasonography was undertaken in 12 non-Hodgkin's lymphoma patients to delineate changes in vascularity, and correlate this response with clinical outcome.

RESULTS

Reduced vascularity in response to chemotherapy was shown to be a positive prognostic sign.

CONCLUSIONS

More persistent nodal vascularity may signify a less favourable prognosis.

Electrocardiographic manifestations: patterns that confound the EKG diagnosis of acute myocardial infarction-left bundle branch block, ventricular paced rhythm, and left ventricular hypertrophy

The 12-lead electrocardiogram (EKG), a powerful tool used in evaluating the chest pain patient, has its shortcomings. One such failing is encountered in a patient with one of the following electrocardiographic patterns: left bundle branch block (LBBB), ventricular paced rhythm (VPR), and left ventricular hypertrophy (LVH). These patterns reduce the ability of the EKG to detect acute coronary ischemic change and acute myocardial infarction (AMI). Several strategies are available to assist in the correct interpretation of these complicated electrocardiographic patterns, including a knowledge of the ST segment-T wave changes associated with these confounding patterns, performance of serial EKGs, and comparison with previous EKGs if available. This article suggests guidelines and interpretive tools for diagnosing AMI on EKG in patients with these confounding patterns.

Comparison of wire-guided cricothyrotomy versus standard surgical cricothyrotomy technique

We compared a wire-guided cricothyrotomy technique vs. standard surgical cricothyrotomy in terms of accuracy in placement, complications, performance time, incision length, and user preference. We conducted a randomized, crossover controlled trial in which Emergency Medicine (EM) attendings and residents performed cricothyrotomies by both standard and wire-guided techniques (using a commercially available kit) on human cadavers after a 15-min training session. Procedure time, incision length, and physician preference were recorded. Cadavers were inspected for accuracy of placement and complications. Airway placement was accurate in 13 of 15 cases for the standard technique (86.7%), and 14 of 15 cases for the wire-guided technique (93.3%). When comparing wire-guided vs. standard techniques, there were no differences in complication rates or performance times. The wire-guided technique resulted in a significantly smaller mean incision length than the standard technique (0.53 vs. 2.53 cm, respectively, p<0.0001). Overall, 14 of 15 physicians stated that they preferred the wire-guided to the standard technique. Our data suggest that this wire-guided cricothyrotomy technique is as accurate and timely to use as the standard technique and is preferred by our physician operators. In addition, the technique results in a smaller incision on human cadaver models.

Nasotracheal intubation in the emergency department, revisited

This retrospective study was designed to investigate the current practice of nasotracheal intubation (NTI) in the Emergency Department (ED) at the University of California, San Diego Medical Center. Over a 5-year period, 21% (105/501) of patients intubated in the ED had at least one NTI attempt. The most frequent primary diagnoses in these patients included drug overdose, congestive heart failure, and chronic obstructive pulmonary disease. We report an overall NTI success rate of 79% (83/105). Sixty-one percent (64/105) of the patients were nasally intubated on the first NTI attempt. Nasal dilators, topical neosynephrine, and sedation improved NTI success rates. Epistaxis and improper tube position were the most common immediate complications. Sinusitis, pneumonia, and sepsis were the most frequent late complications. Patients receiving thrombolytic therapy were at risk of developing severe epistaxis. A prior history of sinus disease may predispose a nasally intubated patient to sinusitis. The complication rates reported here are similar to those of previous studies. A survey of emergency medicine (EM) residency programs found that EM residents throughout the country perform an average of 2.8 NTIs during their residency training. Thus, there is limited exposure to this intubation technique in EM residency programs. Nasotracheal intubation is a useful alternative to oral intubation, particularly when oral access is compromised. While not the optimal approach, we conclude that NTI is still a valuable method for establishing an airway and should remain among the emergency physician's arsenal of intubation techniques.

Electrocardiographic manifestations: acute myopericarditis

Acute, or so-called "dry," myopericarditis occurs in the presence of diffuse inflammation of the pericardial sac and superficial epicardium from a multitude of infectious and inflammatory processes. This inflammation results in a current of myocardial injury resulting from the epicardial irritation manifested by a number of electrocardiographic findings. Classically, the electrocardiographic changes have been described as an evolution through several distinct stages involving ST segment elevation with PR segment depression, normalization of the ST segment abnormality with T wave inversion, and eventual normalization of the electrocardiogram over a period of days to several weeks. The following discussion focuses on the electrocardiographic manifestations of acute myopericarditis and includes findings useful in establishing the diagnosis as well as distinguishing the disease from other syndromes, particularly acute myocardial infarction.

Are heroin overdose deaths related to patient release after prehospital treatment with naloxone?

OBJECTIVE

Naloxone is frequently used by prehospital care providers to treat suspected heroin and opioid overdoses. The authors' EMS system has operated a policy of allowing these patients, once successfully treated, to sign out against medical advice (AMA) in the field. This study was performed to evaluate the safety of this practice.

METHODS

The authors retrospectively reviewed all 1996 San Diego County Medical Examiner's (ME's) cases in which opioid overdoses contributed to the cause of death. The records of all patients who were found dead in public or private residences or died in emergency departments of reasons other than natural causes or progression of disease, are forwarded to the ME office. ME cases associated with opiate use as a cause of death were cross-compared with all patients who received naloxone by field paramedics and then refused transport. The charts were reviewed by dates, times, age, sex, location, and, when available, ethnicity.

RESULTS

There were 117 ME cases of opiate overdose deaths and 317 prehospital patients who received naloxone and refused further treatment. When compared by age, time, date, sex, location, and ethnicity, there was no case in which a patient was treated by paramedics with naloxone within 12 hours of being found dead of an opiate overdose.

CONCLUSIONS

Giving naloxone to heroin overdoses in the field and then allowing the patients to sign out AMA resulted in no death in the one-year period studied. This study did not evaluate for return visits by paramedics nor whether patients were later taken to hospitals by private vehicles.

Permanent cardiac pacemakers: issues relevant to the emergency physician, part II

Many people benefit from the implantation of cardiac pacemakers for management of certain cardiac dysrhythmias. These patients are seen regularly in the Emergency Department with a variety of pacemaker complications and malfunctions. The presence of a pacemaker may also affect management of unrelated medical problems. This, the second of a two-part series, covers the causes, diagnosis, and management of pacemaker malfunction; the pacemaker syndrome; the pacemaker Twiddler's syndrome; and other considerations in the paced patient including diagnosis of acute myocardial infarction, ACLS protocols, trauma, and sources of interference.

Electrocardiographic manifestations: benign early repolarization

Early repolarization, also known as benign early repolarization (BER) or normal variant, is noted in approximately 1% of the population and in up to 48% of patients seen in the Emergency Department with chest pain. BER represents a benign variant of the normal electrocardiogram and is one of several syndromes producing electrocardiographic ST segment elevation (STE). The electrocardiogram (EKG) findings of BER include diffuse or widespread ST segment elevation, upward concavity of the initial portion of the ST segment, notching or slurring of the terminal QRS complex, and concordant T waves of large amplitude. This article focuses on BER and includes the electrocardiographic findings useful in making the diagnosis as well as distinguishing BER from other STE syndromes.

Permanent cardiac pacemakers: issues relevant to the emergency physician, Part I

Many people benefit from the implantation of cardiac pacemakers for management of certain cardiac dysrhythmias. These patients are seen regularly in the emergency department with a variety of pacemaker complications and malfunctions. The presence of a pacemaker may also affect management of unrelated medical problems. This two-part series reviews the medical issues related to patients with permanent pacemakers. Part I covers pacing modes and terminology, complications of the implant procedure, and the approach to a patient with a permanent pacemaker. Part II covers the causes, diagnosis and management of pacemaker malfunction; the pacemaker syndrome; the pacemaker Twiddler's syndrome; and other considerations in the paced patient including diagnosis of acute myocardial infarction, ACLS protocols, trauma, and sources of interference. Indications for permanent pacemaker implantation and temporary external pacing will not be covered.

Emergency department airway management before and after an emergency medicine residency

To determine whether the start of an Emergency Medicine (EM) training program affects the appropriateness, timeliness, and safety of Emergency Department (ED) intubations, all ED intubations performed 12 months before and after the start of an EM residency were reviewed. In addition, all patients intubated within 12 h after being admitted through the ED were reviewed. We found that all ED intubations before and after the start of a residency program were deemed appropriate. Of patients intubated after admission, 13 of 20 (65%) were felt to have warranted intubation while in the ED for the pre-residency group, compared with 9 of 29 patients (31%) for the post-residency group. There were no differences between the complication rates of these groups. We conclude that an EM residency program did not increase the number of inappropriate intubations or complications, and reduced the number of patients who required but did not receive intubation in the ED.

The reproducibility of cephalometric landmarks: an experimental study on skulls

Few previous cephalometric studies have used dry skulls in order to eliminate the effects of the facial soft tissues. The aim of this study were to quantify the intra-examiner reproducibility of the commonly used cephalometric landmarks, angles and distances, using dry skulls and to compare these errors with previous error data obtained from normal cephalograms of living patients. Thirty skulls were mounted in a purpose-designed holder and repeat cephalograms of each skull were recorded and digitised. All measurements were made relative to an X-Y coordinate reference grid. Scattergrams were produced to show the characteristic distribution of the intra-examiner reproducibility errors for the landmarks, and the reproducibility of the angles and distances were tabulated. This data was compared with a related study that included the soft tissue profile. The standard deviations of the skeletal and dental angles and distances were greater in the presence of the soft tissues. These differences were up to four times larger for measurements including the location of Nasion (e.g. SNA, SNB and SNPg), which was the landmark location most affected by the presence of soft tissues, and for the distance: Incisal tip of Lower Incisor to Pogonion. Anterior Nasal Spine, in the horizontal plane, was also greatly affected by the presence of the soft tissues. By using dry skulls, the errors observed in this study may serve as standards for the rational interpretation of clinical cephalometric values.

Reexamination of custody restraint position and positional asphyxia

The use of the hogtie restraint (also known as hobble or prone maximal restraint) by law enforcement and prehospital personnel has come under scrutiny because of reports of sudden deaths in persons placed in this restraint position. Some contend that this body position restricts chest and abdominal movement to the point that individuals are at risk for hypoventilatory respiratory compromise and "positional" asphyxiation. We review case reports of custody deaths in subjects placed in the hogtie position, as well as related medical literature regarding positional asphyxia. We also review the current research findings from human physiology studies that have investigated the effects of the hogtie position on respiratory and pulmonary function. We conclude that the hogtie restraint position by itself does not cause respiratory compromise to the point of asphyxiation and that other factors are responsible for the sudden deaths of individuals placed in this position.

Postpartum coronary artery dissection

A 34-year-old woman presented to the emergency department 12 weeks postpartum with chest pain. An ECG indicated an acute myocardial infarction. The patient underwent cardiac catheterization with findings suggestive of coronary artery dissection later confirmed on intravascular ultrasonography. She underwent emergency coronary artery bypass grafting and has subsequently done well.

Intracisternal osteogenic protein-1 enhances functional recovery following focal stroke

Osteogenic protein-1 (OP-1, BMP-7) is a member of the transforming growth factor-beta (TGF-beta) superfamily that selectively induces dendritic outgrowth from cultured neurons. We injected human recombinant OP-1 (1 or 10 micrograms) or vehicle into the cisterna magna of mature male Sprague-Dawley rats 1 and 4 days after focal cerebral infarction induced by middle cerebral artery (MCA) occlusion. OP-1 treatment was associated with a marked enhancement of recovery of sensorimotor function of the impaired forelimb and hindlimb (contralateral to infarcts) as assessed by limb placing tests. This effect appeared to be dose dependent. There was no difference in infarct volume between OP-1 and vehicle-treated rats. The mechanisms of enhanced recovery by intracisternal OP-1 may include promotion of dendritic sprouting in the intact uninjured brain.

Recombinant human osteogenic protein-1 (OP-1) stimulates periodontal wound healing in class III furcation defects

Osteogenic protein-1 (OP-1) is a member of the transforming growth factor beta superfamily and is a potent modulator of osteogenesis and bone cell differentiation. This preclinical study in dogs sought to assess the effects of OP-1 on periodontal wound healing in surgically created critical size Class III furcation defects. Eighteen male beagle dogs were subjected to the creation of bilateral mandibular 5 mm osseous defects. A split-mouth design was utilized which randomly assigned opposing quadrants to control therapy (surgery alone or collagen vehicle) or 1 of 3 ascending concentrations of OP-1 in a collagen vehicle (0.75 mg OP-1/g collagen, 2.5 mg/g, or 7.5 mg/g). Thus, 9 quadrants per test group received OP-1, 9 quadrants per control group received surgery alone, and 9 quadrants received collagen vehicle alone. Test articles were delivered by a surgeon masked to the treatment, and fluorogenic bone labels were injected at specified intervals post-treatment. Eight weeks after defect creation and OP-1 delivery, tissue blocks of the mandibulae were taken for masked histomorphometric analysis to assess parameters of periodontal regeneration (e.g., bone height, bone area, new attachment formation, and percent of defect filled with new bone). Histomorphometry revealed limited evidence of osteogenesis, cementogenesis, and new attachment formation in either vehicle or surgery-alone sites. In contrast, sites treated with all 3 concentrations of OP-1 showed pronounced stimulation of osteogenesis, regenerative cementum, and new attachment formation. Lesions treated with 7.5 mg/g of OP-1 in collagen regenerated 3.9+/-1.7 mm and 6.1+/-3.4 mm2 (mean +/-S.D.) of linear bone height and bone area, respectively. Furthermore, these differences were statistically different from both control therapies for all wound healing parameters (P < 0.0001). No significant increase in tooth root ankylosis was found among the treatment groups when compared to the surgery-alone group. We conclude that OP-1 offers promise as an attractive candidate for treating severe periodontal lesions.

Outcome study of prehospital patients signed out against medical advice by field paramedics

STUDY OBJECTIVE

To describe the incidence and demographic data of prehospital patients who contact paramedics by way of the 911 system, refuse transport against medical advice (AMA), then call 911 and are subsequently reevaluated by paramedics in the following 48 hours.

METHODS

We conducted a retrospective observational review of records using the San Diego County Quality Assurance Network database for prehospital providers. All paramedic 911 responses that made base hospital contact over a 3-month period were reviewed to identify patients who signed out AMA. The main outcome measure was to identify patients who signed out AMA and then called 911 again within 48 hours. The demographics, complaints, treatments, and dispositions of these patients are described.

RESULTS

Of 6,512 total 911 responses reviewed, 443 (7%) involved patients who signed out AMA. Of these patients, 156 cases (35.2%) were listed as trauma and 287 (64.8%) were medical, with cardiac chest pain, seizure, and respiratory distress/shortness of breath the most frequently noted medical subcategories. Fifty-one (11.5%) such patients received treatment; 34 received dextrose, 12 naloxone, 4 albuterol, and 1 a splint. Patient names were available in 5,515, of the total 6,512 responses and 431 of the 443 AMA cases, permitting computer searching of reevaluations by paramedics. Of the 431 AMA patients for whom a name was available, 10 (2%) called 911 again within 48 hours. All 10 callbacks were made for a related chief compliant, and all 10 of these patients were transported (4 admitted to hospital, 1 died en route, 1 transferred to another facility, 4 discharged from the ED). Of these 10 patients, 7 (70%) were older than 65 years, compared with 17% of all AMA patients older than 65 years.

CONCLUSION

On the basis of our findings, patients over the age of 65 years have a propensity to recontact paramedics and should be aggressively encouraged to seek emergency medical treatment. Future prospective studies should be mounted to examine at patient outcome and to assess why patients sign out AMA after making contact with paramedics.

Restraint position and positional asphyxia

STUDY OBJECTIVE

To determine whether the "hobble" or "hog-tie" restraint position results in clinically relevant respiratory dysfunction.

METHODS

This was an experimental, crossover, controlled trial at a university-based pulmonary function laboratory involving 15 healthy men ages 18 through 40 years. Subjects were excluded for a positive urine toxicology screen, body mass index (BMI) greater than 30 kg/m2, or abnormal screening pulmonary function testing (PFT). Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and maximal voluntary ventilation (MVV) were obtained with subjects in the sitting, supine, prone, and restraint positions. After a 4-minute exercise period, subjects rested in the sitting position while pulse, oxygen saturation, and arterial blood gases were monitored. The subjects repeated the exercise, then were placed in the restraint position with similar monitoring.

RESULTS

There was a small, statistically significant decline in the mean FVC (from 5.31 +/- 1.01 L [101% +/- 10.5% of predicted] to 4.60 +/- .84 L [88% +/- 8.8% of predicted]), mean FEV1 (from 4.31 +/- .53 L [103% +/- 8.4%] to 3.70 +/- .45 L [89% +/- 7.7%]), and mean MVV (from 165.5 +/- 24.5 L/minute [111% +/- 17.3%] to 131.1 +/- 20.7 L/minute [88% +/- 16.6%]), comparing sitting with restraint position (all, P < .001). There was no evidence of hypoxia (mean oxygen tension [PO2] less than 95 mm Hg or co-oximetry less than 96%) in either position. The mean carbon dioxide tension (PCO2) for both groups was not different after 15 minutes of rest in the sitting versus the restraint position. There was no significant difference in heart rate recovery or oxygen saturation as measured by co-oximetry and pulse oximetry.

CONCLUSION

In our study population of healthy subjects, the restraint position resulted in a restrictive pulmonary function pattern but did not result in clinically relevant changes in oxygenation or ventilation.

Drug-induced hyperthermia

Drug-related causes of hyperthermia can often be overlooked in the setting of elevated body temperature. This article reviews the pathophysiology, presentation, and treatment of several drug-induced hyperthermia syndromes: malignant hyperthermia, neuroleptic malignant syndrome, sympathomimetic poisoning, and anticholinergic toxicity. Although the general approach is similar, specific management strategies may be required for each syndrome.

Patients' satisfaction when denied authorization for emergency department care by their managed care plan

We conducted a survey of managed care plan (MCP) patients who presented to the emergency department (ED) but were denied insurance authorization during a 3-month period. Patients were identified by triage or registration records, contacted by telephone after their visit, and surveyed regarding their satisfaction with the ED and MCP, follow-up care, and future behavior. We surveyed 72 (73.4%) of 98 subjects who were denied authorization. Forty-nine (68.1%) were redirected to a clinic or primary physician, 14 (19.4%) to an urgent care or other ED, and 9 (12.5%) were given no follow-up. Fifty-five respondents (76.4%) stated they had followed-up as directed, but 34 (47.2%) felt the delay had a negative impact. Thirty-nine (54.2%) were dissatisfied with their MCP. If their problems were to recur, 27 (37.5%) stated they would go to a clinic or call their MCP, but 34 (47.2%) would return to the ED. Many patients who are denied authorization are dissatisfied with their MCP and will return to the ED in the future, despite previous denials.

The situational effects on haptic perception of rod length

Three experiments were conducted to investigate situational effects (manipulation, range, and prior experience) on the haptic perception of rod length. Each rod was held between its two ends with one hand. In Experiment 1, 32 participants judged length of rods using different manipulations. Perceived lengths were found to be dependent on manner of manipulation and not necessarily equal to actual lengths. Different parameters were detected in different manipulations. In Experiment 2, 8 participants judged rod lengths by wielding rods of two ranges: long and short. Perceived length was found to be affected by the range of rods evaluated successively in a single set. In Experiment 3, 9 participants judged rod lengths after an experience of handling dense or light rods. Perceived length was found to be affected by prior experience. Results are discussed in terms of how rod lengths can be perceived accurately by haptic modality without involving direct perception.

A skull-holding device for experimental cephalometric research

This paper describes and illustrates an innovative versatile skull-holding device for experimental research in cephalometrics. Repositioning of the skulls was evaluated and found to be highly reproducible.

Survey of illegal immigrants seen in an emergency department

There is growing controversy regarding illegal immigrants and their use of social services, including health care, in this country. We surveyed undocumented persons presenting at our emergency department to investigate the reasons why they sought care in the United States. Overall, 227 visits (8.6%) were made in the emergency department by illegal immigrants, mostly Hispanics. Of 104 patients surveyed, all sought care in this country because they were here at the time, and 86 (83%) intended to remain permanently. Of the 104 persons, 83 (80%) cited lack of funding as a reason for seeking emergency department care. Undocumented Hispanics had a higher uninsured rate (64%) than both Hispanics (32%) and non-Hispanics (30%). Of the 104 patients, 38 (36%) had difficulty obtaining care elsewhere because of their status, 53 (51%) knew of no other sources of care, and 46 (44%) said that even if available, only the emergency department was acceptable. Many undocumented persons seek care in the United States because they reside here permanently, often using this emergency department as their source of care. These findings may be important in light of recent efforts to restrict services for this group.

Ultrastructure and cytochemical staining characteristics of canine natural killer cells

BACKGROUND

The purpose of this work was to describe the ultrastructure and cytochemical staining characteristics of canine peripheral blood lymphocytes with natural killer (NK) cell activity, with comparison made to non-NK lymphocytes.

METHODS

Canine lymphocyte populations evaluated for ultrastructure, cytochemical staining, and NK function (by 51chromium release assay) included: peripheral blood lymphocytes; lymphocytes from band 1 (NK-enriched), band 2, and the pellet of a 45/50% percoll gradient; lymphocytes from the supernatant fluid (non-conjugated lymphocytes) and pellet (lymphocytes conjugated to tumor cell targets) of a 17% percoll gradient; and null (CD4-CD8-) and CD4-CD8+ lymphocytes.

RESULTS

NK activity was concentrated in band 1 lymphocytes of the 45/50% percoll gradient with further enhancement of activity occurring in sorted null cells. Canine NK cells were 5.5 to 6.5 microns in diameter with a reniform (kidney bean shape) nucleus, and electron-dense cytoplasmic granules. NK cells (percoll band 1 cells and null cells) had larger cell and nuclear area, and less round nuclei when compared to non-NK lymphocytes. The overall cytochemical staining (chloracetate esterase, peroxidase, sudan black B, naphthyl acetate esterase, naphthyl butyrate esterase periodic acid-Schiff stain, and acid phosphatase with and without tartrate) pattern was similar in all the lymphocyte populations evaluated.

CONCLUSIONS

This work confirms the usefulness of a 45/50% percoll gradient in obtaining a NK-enriched fraction of canine lymphocytes, and shows further enhancement of NK activity in sorted CD4- CD8- cells. The ultrastructure of canine NK cells is similar to that reported for human NK cells, but is different from that of other canine peripheral blood lymphocytes. Standard cytochemical staining does not discriminate canine NK cells from other lymphocytes.

Formic acid skin burns resulting in systemic toxicity

Systemic toxicity developed in a 3-year-old girl burned by formic acid over 35% of her total body surface area. The patient presented with profound metabolic acidosis and a serum formate level of 400 micrograms/mL, the highest reported in the literature for poisoning by any route. The patient was successfully treated with hemodialysis, IV bicarbonate, and supportive measures. Reports of formic acid skin burns and systemic toxicity are limited. We discuss the pathophysiology and treatment of these cases.