Biomedical subjects

Theodore C Chan

Publications and source records attributed to Theodore C Chan.

At least 37 records · Page 2Linked to original sources

PubMed2004

Electrocardiographic manifestations: electrolyte abnormalities.

Because myocyte depolarization and repolarization depend on intra- and extracellular shifts in ion gradients, abnormal serum electrolyte levels can have profound effects on cardiac conduction and the electrocardiogram (EKG). Changes in extracellular potassium, calcium, and magnesium levels can change myocyte membrane potential gradients and alter the cardiac action potential. These changes can result in incidental findings on the 12-lead EKG or precipitate potentially life-threatening dysrhythmias. We will review the major electrocardiographic findings associated with abnormalities of the major cationic contributors to cardiac conduction-potassium, calcium and magnesium.

Adult↗

PubMed2004

Anterior shoulder dislocations: beyond traction-countertraction.

The shoulder is the most commonly dislocated large joint presenting to American Emergency Departments (ED). Anterior dislocations account for the great majority of these dislocations. Most anterior shoulder dislocations can be reduced in the ED using a variety of reduction techniques. The traction-countertraction technique is quite familiar to most Emergency Physicians, however, many other effective methods of reduction have been described. No method has proven 100% successful, and occasionally multiple attempts using different techniques are required to effect reduction. This article reviews some of the other techniques used to reduce anterior shoulder dislocations, variations reported on these techniques, and their success rates, advantages, and disadvantages.

Emergency Medical Services↗

PubMed2004

Weight force during prone restraint and respiratory function.

Prone maximal restraint position (PMRP, also known as hogtie or hobble) is often used by law enforcement and prehospital personnel on violent combative individuals in the field setting. Weight force is often applied to the restrained individual's back and torso during the restraint process. We sought to determine the effect of 25 and 50 lbs weight force on respiratory function in human subject volunteers placed in the PMRP. We performed a randomized, cross-over, controlled trial on 10 subjects placed in 4 positions for 5 minutes each: sitting, PRMP, PRMP with 25 lbs weight force (PMRP+25), and PRMP with 50 lbs weight force placed on the back (PMRP+50). We measure pulse oximetry, end-tidal CO2 levels, and forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). FVC and FEV1 were significantly lower in all restraint positions compared with sitting but not significantly different between restraint positions with and without weight force. Moreover, mean oxygen saturation levels were above 95% and mean end-tidal CO2 levels were below 45 mm Hg for all positions. We conclude that PMRP with and without 25 and 50 lbs of weight force resulted in a restrictive pulmonary function pattern but no evidence of hypoxia or hypoventilation.

Adult↗

PubMed2004

9-1-1 responses for shopping cart and stroller injuries.

BACKGROUND: On average, 24,000 children a year are treated in the emergency departments (EDs) for shopping cart injuries, with over 650 children a year requiring hospital admission. The authors sought to evaluate the incidence and outcomes of children in the community evaluated by paramedics because they were injured in shopping cart or stroller-related incidences. METHODS: Retrospective design in which prehospital patients records were searched for all patients under 14 years old who were injured in an incident involving a shopping cart or stroller and were responded to by paramedics. Records were reviewed for demographics, injury type, and disposition. RESULTS: During the 3 1/2 year study period, a total of 241 cases were identified with 120 being shopping cart-related and 121 stroller-related. The most frequent ages for stroller injuries were 0 to 6 months and for shopping cart injuries was one year of age. Falls were the most common mechanism of injury, 70.3% for shopping carts and 47.5% for strollers, with head injuries accounting for 53% and 59% of the primary injuries in each group. An additional 12% and 18% suffered primary facial injuries. 77% of patients were transported by paramedics to an ED for evaluation, with 19% of parents signing out against medical advice. 8.2% were admitted to the hospital and there were no deaths. CONCLUSIONS: Shopping cart and stroller-related injuries are a common mechanism of injury for pediatric patients responded to by paramedics. This is an area which continued parental education is needed.

Accidental Falls↗

PubMed2004

Information technology and emergency medical care during disasters.

Disaster response to mass-casualty incidents represents one of the greatest challenges to a community's emergency response system. Rescuers, field medical personnel, and regional emergency departments and hospitals must often provide care to large numbers of casualties in a setting of limited resources, inadequate communication, misinformation, damaged infrastructure, and great personal risk. Emergency care providers and incident managers attempt to procure and coordinate resources and personnel, often with inaccurate data regarding the true nature of the incident, needs, and ongoing response. In this chaotic environment, new technologies in communications, the Internet, computer miniaturization, and advanced "smart devices" have the potential to vastly improve the emergency medical response to such mass-casualty incident disasters. In particular, next-generation wireless Internet and geopositioning technologies may have the greatest impact on improving communications, information management, and overall disaster response and emergency medical care. These technologies have applications in terms of enhancing mass-casualty field care, provider safety, field incident command, resource management, informatics support, and regional emergency department and hospital care of disaster victims.

California↗

PubMed2003

Electrocardiographic manifestations: narrow QRS complex tachycardias.

Narrow QRS complex tachycardia is a common dysrhythmia in Emergency Medicine practice. Diagnosis and mechanism often can be made by 12-lead electrocardiographic (EKG) analysis but may subsequently require electrophysiologic testing. The clinical manifestations are varied and dependent upon heart rate, prior cardiac disease, and general physiologic status. Patient management is directed towards the etiology and mechanism of the dysrhythmia and includes vagal maneuvers, pharmacologic therapy, and cardioversion. Hemodynamically compromised patients must be promptly treated. Patients are often admitted to the hospital but selected patients can be safely discharged from the Emergency Department for outpatient evaluation and management. Pediatric and pregnant patients are, in general, treated the same as adults. Several case examples and EKGs are presented.

Adult↗

PubMed2003

Electrocardiographic manifestations: wide complex tachycardia due to accessory pathway.

Tachycardia with a wide QRS complex is usually due to ventricular tachycardia (VT), supraventricular tachycardia (SVT) with aberrant intraventricular conduction, or an accessory pathway-mediated dysrhythmia. The most common type of accessory pathway causing a wide complex tachycardia is the atrioventricular bypass tract. Distinguishing the accessory pathway-mediated tachycardia from VT or SVT with aberrancy is often difficult, but has important clinical consequences. This article will review the diagnosis of wide complex tachycardia due to an accessory pathway and its related management in the emergent setting.

Adult↗

PubMed2003

Safety and effectiveness of methohexital for procedural sedation in the emergency department.

Use of methohexital as an agent for moderate procedural sedation in the Emergency Department (ED) recently has increased. As a barbiturate, potential complications include respiratory and myocardial depression. We conducted a retrospective review of medical records and procedural flow charts for all use of methohexital in our ED during a 31-month period. We collected data on medication use, adjunctive medications, indications, procedural success, and complications. Overall, there were 114 orthopedic procedures performed using methohexital (mean dose of 1.43 mg/kg) for sedation on 104 patients. Procedures included shoulder dislocation reduction (26.3%), hip dislocation reduction (25.4%), elbow dislocation reduction (15.2%), and fracture reduction (25.4%). There was an 80.8% success rate with the first dose of methohexital. Complications occurred in 20.2% of patients and included oxygen desaturation, hypotension, hypoventilation, vomiting, tremor, and airway obstruction. All complications were transient and managed without sequelae. Use of concurrent parenteral opioid medications had no significant impact on success or complications.

Adolescent↗

PubMed2003

Electrocardiographic manifestations: bundle branch blocks and fascicular blocks.

Intraventricular conduction block is the general name given to a varied group of electrocardiographic entities. All share a common finding of some degree of delay in ventricular activation; recognition of these blocks hinges upon analysis of the QRS complex, as well as the ST-T changes associated with them. Bundle branch block (right or left), and fascicular block (left anterior or left posterior) are all examples of intraventricular conduction block. Causation of intraventricular conduction block may be cardiac or noncardiac; early recognition of the etiology may be of clinical importance. This article reviews the basic anatomy and physiology related to intraventricular conduction blocks, and then examines each in terms of electrocardiographic definition and clinical correlation.

Bundle-Branch Block↗

PubMed2003

Electrocardiographic manifestations: ventricular tachycardia.

Ventricular tachycardia is a serious rhythm disturbance that originates from any part of the myocardium or conduction system below the atrioventricular node. Ventricular tachycardia (VT) presents with a wide QRS complex and a rate greater than 120 beats/min. Ventricular tachycardia is frequently encountered as a complication of coronary artery disease or cardiomyopathy; furthermore, VT is also seen in patients with medication adverse effect or electrolyte disturbance. Ventricular tachycardia presents electrocardiographically in several forms, including monomorphic and polymorphic VT. As is true in most Emergency Department presentations, the Emergency Physician must approach the dysrhythmic patient from an undifferentiated perspective, in this instance, the wide complex tachycardia (WCT) scenario. The electrocardiographic differential diagnosis of WCT classically includes VT and supraventricular tachycardia with aberrant intra-ventricular conduction. This article will review the electrocardiographic presentations encountered in patients with ventricular tachycardia.

Aged↗

PubMed2003

Assessment for deaths in out-of-hospital heroin overdose patients treated with naloxone who refuse transport.

UNLABELLED: Naloxone frequently is used to treat suspected heroin and opioid overdoses in the out-of-hospital setting. The authors' emergency medical services system has operated a policy of allowing these patients, when successfully treated, to sign out against medical advice (AMA) in the field. OBJECTIVES: To evaluate the safety of this AMA policy. METHODS: This is a retrospective review of out-of-hospital and medical examiner (ME) databases over a five-year period. The authors reviewed all ME cases in which opioid overdoses were listed as contributing to the cause of death. These cases 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 ethnicity when available. RESULTS: There were 998 out-of-hospital patients who received naloxone and refused further treatment and 601 ME cases of opioid overdose deaths. When compared by age, time, date, sex, location, and ethnicity, there were no cases in which a patient was treated by paramedics with naloxone within 12 hours of being found dead of an opioid overdose. CONCLUSIONS: Giving naloxone to patients with heroin overdoses in the field and then allowing them to sign out AMA resulted in no identifiable deaths within this study population.

Adolescent↗

PubMed2002

Out-of-hospital pediatric intubation by paramedics: the San Diego experience.

To evaluate pediatric endotracheal intubations by our paramedics, we performed a retrospective review of a prehospital computer database, quality assurance reviews, and prehospital run sheets for all patients under 15 years of age who had an endotracheal tube (ETT) placed. During the 4.5-year study period, 324 pediatric patients had intubation attempts by field paramedics, of which 264 (82%) were successful and three were reported esophageal and unrecognized by the paramedic. Two of these esophageal placements were noted on arrival at the hospital, and one upon turn-over of patient care to a nurse of an aeromedical service. All three intubations were deemed esophageal with direct laryngoscopy, and the patients had been in cardiopulmonary arrest status prior to the intubation. Of the 264 patients who had ETT placed, 99% were endotracheal, while only 1% were unrecognized esophageal. We conclude that pediatric endotracheal intubation by out-of-hospital paramedics in an established EMS system has a low occurrence of unrecognized esophageal placements.

California↗

PubMed2002

Electrocardiographic manifestations: right ventricular infarction.

The 12-lead electrocardiogram (EKG) is an essential tool when evaluating the Emergency Department (ED) patient with suspected cardiac ischemia. The standard EKG has limitations when evaluating "remote" areas of the heart such as the left posterior wall or right ventricular wall. Diagnosis of right ventricular infarction (RVI) in the presence of acute inferior wall myocardial infarction (MI) is made utilizing right-sided chest leads with high sensitivities and specificities. RVI is a serious ED problem because morbidity and mortality is higher in acute MIs associated with RVI.

Angioplasty, Balloon, Coronary↗

PubMed2002

An evaluation of the risk for latex allergy in prehospital EMS providers.

Hospital health care providers are increasingly being diagnosed as latex sensitive or allergic. Little is established on incidence or risks to prehospital health care providers. A written survey of EMT-DCs and EMT-Ps was done anonymously using established risk stratification questions to identify factors that indicate higher potential for developing latex allergies. There were 666 surveys distributed with 580 (87%) returned completed. Of the respondents, 533 were male (91%) with 510 (87%) reporting more than 5 years of field experience. Of the survey participants, 435 (75%) were EMT-DC level and 145 (25%) were EMT-P level. We found that latex sensitivities and allergies are present in our population, with an 8% incidence of latex allergies in EMT-DCs and 18% in EMT-Ps. A greater number of respondents report having factors that have been established to be associated with increased risk for latex allergies, indicating the need for more vigilant monitoring for the development of such reactions.

Data Collection↗

PubMed2002

Toomey syringe aspiration may be inaccurate in detecting esophageal intubation after gastric insufflation.

We sought to determine whether gastric distention from air insufflation affects the accuracy of the Toomey syringe in detecting esophageal intubation. We conducted a randomized, single-blinded, crossover trial using human cadavers in which cuffed endotracheal (ET) tubes were placed into the esophagus and trachea. Operators used the Toomey syringe to determine the location of the ET tube before and after gastric insufflation via Ambu-bag ventilation. Greater amounts of air were aspirated (35.4 cc vs. 13.7 cc, respectively, p < 0.001) and less resistance was noted on a five-point scale (3.2 vs. 4.8, respectively, p < 0.001) from esophageally placed ET tubes after gastric insufflation. Sensitivity in detecting esophageally placed ET tubes decreased from 100% in noninsufflated cadavers to only 58% after gastric insufflation (p < 0.001). In the thawed fresh frozen cadaveric model, the Toomey syringe was unreliable in detecting an esophageal intubation after gastric distention insufflation.

Adult↗

PubMed2002

Evaluating the utilization of a regional poison center by Latino communities.

BACKGROUND: Penetrance values estimate the utilization of poison centers services. For a variety of reasons, penetrance values may vary greatly among geographic areas of population. We examined the relationship between ethnicity and penetrance in our population. METHODS: We conducted a retrospective review of data from January 1, 2000 through December 31, 2000 from our poison center's database. Home calls to the center were evaluated by zip code, age, gender, substance, route of exposure, and outcome. These data were compared with U.S. Census 2000 geographic and community demographic data for San Diego by zip code. From this information, we identified zip code regions with substantial Latino populations (>50%), and substantial Caucasian populations (>70%). Study groups were limited to those zip codes with median household incomes of $20,000-$50,000. Aggregate total and pediatric penetrance values were calculated for each group and compared. RESULTS: Our study group consisted of 6 zip codes with significant numbers of Latino residents, and 11 zip codes with significant numbers of Caucasian residents. Aggregate call volume for the county was 6.5 calls per 1000 population, while that for children less than age 5 was 43. Penetrance values for the study zip codes with large Latino populations were significantly lower with a mean value of 22.4 for children, and 5.0 for all ages. These values were statistically significant when compared to county data and that from the control zip codes with largely Caucasian residents (61 aggregate and 49.6 pediatric). CONCLUSION: Penetrance values were significantly lower in zip codes with large numbers of Latino residents. Reasons for this variation are being investigated.

California↗

PubMed2002

The effect of oleoresin capsicum "pepper" spray inhalation on respiratory function.

We performed a randomized, cross-over controlled trial to assess the effect of Oleoresin capsicum (OC) spray inhalation on respiratory function by itself and combined with restraint. Thirty-five subjects were exposed to OC or placebo spray, followed by 10 min of sitting or prone maximal restraint position (PMRP). Spirometry, oximetry, and end-tidal CO2 levels were collected at baseline and throughout the 10 min. Data were compared between groups (ANOVA) and with predefined normal values. In the sitting position, OC did not result in any significant changes in mean percent predicted forced vital capacity (%predFVC), percent predicted forced expiratory volume in 1 s (%predFEV1), oxygen, or CO2 levels. In PMRP, mean %predFVC and %predFEV1 fell 14.4 and 16.5% for placebo and 16.2 and 19.1% for OC, but were not significantly different by exposure. There was no evidence of hypoxemia or hypercapnia in either groups. OC exposure did not result in abnormal spirometry, hypoxemia, or hypoventilation when compared to placebo in either sitting or PMRP.

Adult↗

PubMedDate not supplied

Airway obstruction in children aged less than 5 years: the prehospital experience.

BACKGROUND: Treatment of choking in children has been well studied, but few data are available on the various causes of the choking episodes in the pediatric population. OBJECTIVES: To assess frequency and to stratify etiologies of children less than 5 years of age who had a 911 advanced life support (ALS) ambulance response for airway obstruction. METHODS: A prehospital database was searched and information was collected defining type of obstruction, age of the child, parents' action, paramedic treatment, and incident outcome. RESULTS: There were 182 patients with airway obstruction under 5 years of age, of whom 99 (55%) were less than 1 year old. Liquid obstructions (i.e., formula, juices) were most common in the youngest children, whereas solid food and nonfood solid obstructions were most prevalent in children over 1 year old. One hundred seven (59%) of these obstructions resolved before paramedic arrival (69% of liquid obstructions, 72% of food, and 36% of nonfood solid objects). Interventions used by parents included bulb suction (3%), finger sweeps (6%), Heimlich maneuver (3%), and back blows (12%). Paramedics used ALS skills in only three cases. After paramedic evaluation, 47% of parents refused transport against medical advice (AMA). CONCLUSIONS: Although most episodes of pediatric airway obstruction will have been resolved by the time of paramedic arrival, age-specific and item-specific treatment skills need to be reinforced with parents and prehospital providers.

Age Factors↗