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Biomedical subjects

T C Chan

Publications and source records attributed to T C Chan.

104 records · Page 6Linked to original sources
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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.

Adolescent↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

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.

Electrodes, Implanted↗
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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.

Electrocardiography↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

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.

Acute Disease↗
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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.

Attitude of Health Personnel↗
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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.

California↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

Piroxicam therapy in 34 dogs with transitional cell carcinoma of the urinary bladder.

Thirty-four dogs with histopathologically confirmed, measurable, nonresectable transitional cell carcinoma of the urinary bladder were treated with piroxicam (0.3 mg/kg PO sid) and were evaluated for tumor response and drug toxicity. Dogs were evaluated at the Purdue University Veterinary Teaching Hospital by means of physical examination, thoracic and abdominal radiography, cystography, complete blood count, serum biochemistry profile, and urinalysis. In selected cases, prostaglandin E2 (PGE2) concentrations in plasma and in supernatants of stimulated monocytes, and natural killer cell activity were quantified. Dogs were evaluated before therapy and at 28 and 56 days after initiation of therapy. Dogs with stable disease or remission at 56 days remained on the study and were evaluated at 1 to 2 months intervals. Tumor responses were 2 complete remissions, 4 partial remissions, 18 stable diseases, and 10 progressive diseases. The median survival of all dogs was 181 days (range, 28 to 720+ days), with 2 dogs still alive. Piroxicam toxicity consisted of gastrointestinal irritation in 6 dogs and renal papillary necrosis (detected at necropsy) in 2 dogs. Monocyte production of PGE2 appeared to decrease with therapy in dogs whose tumors were decreasing in size, and increased in dogs with tumor progression. A consistent pattern in natural killer cell activity was not observed. In vitro cytotoxicity assays against 4 canine tumor cell lines revealed no direct antitumor effects of piroxicam. In summary, antitumor activity, which was not likely the result of a direct cytotoxic effect, was observed in dogs with transitional cell carcinoma of the bladder treated with piroxicam.

Administration, Oral↗
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Chronic ethanol consumption, stress, and hypertension.

A reliable method of producing physical stress in the rat was developed using heat irradiation, and the possible interaction between chronic ethanol consumption and stress was investigated in a rat model of alcoholism. Chronic heat stress and chronic ethanol consumption each produced mild hypertension in rats. When combined, the two treatments resulted in hypertension more severe than that produced by either stress or ethanol consumption alone. The group of animals receiving both treatments also exhibited high mortality. Investigations into the mechanisms responsible for the apparent additive effects of the two treatments revealed that the animals in this group had the highest circulating norepinephrine levels. The plasma volumes, however, were not different between the stressed groups and their unstressed counterparts. As the plasma norepinephrine level usually reflects overall sympathetic tone of an animal, our results suggest that the additional hypertensive effect of chronic stress on the ethanol-treated animals is associated with increased sympathetic nervous activity and is not a result of expanded plasma volume. These findings may have clinical implications for human alcoholics and in the analysis of cardiovascular risk factors in hypertensive patients.

Alcoholism↗
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[The role of inhibition processes in the development of functional properties of neurons of the vibrissa projection area in the cat somatosensory cortex].

The paper deals with the contribution of intracortical inhibitory processes to the organization of receptive fields in the vibrissae projection area of the somatosensory cortex. Inhibition blockade by means of microelectrophoretic application of picrotoxin and bicucullin was shown to lead to a loss of directional sensitivity of neurones. Activation of inhibition at remote glutamate application led to opposite changes: the neurones became directionally sensitive, and dependence was found between the spatial localization of activated neurones and the character of changes of detector parameters. Inhibitory processes caused by natural afferent stimulation led to similar changes of functional characteristics of neurones.

Afferent Pathways↗