Biomedical subjects
Publications and source records attributed to C R Gomez.
Explore the source record for details and available documents.
BACKGROUND: Sinus arrest is a rare complication of metoclopramide administration. CASE DESCRIPTION: A 51-year-old woman developed Guillain-Barre syndrome and severe dysautonomia. Metoclopramide was administered for the treatment of gastroparesis. Sinus arrest followed drug administration on several occasions and on rechallenge. CONCLUSIONS: After reviewing the literature and discussing possible etiologies for this unusual adverse drug reaction in this setting, we recommend that metoclopramide be used with caution in patients prone to develop bradyarrythmias, particularly those with dysautonomias and Guillain-Barre syndrome.
I describe my design for a ventriculostomy stylet fitted with a phase array ultrasonic imaging device in its tip. Theoretically, this would allow identification of the ventricles and their exact location at the bedside, without the need for expensive stereotactic equipment. A device such as this could potentially facilitate the placement of ventriculostomy catheters in patients with small ventricles, and it could even contribute to the education of neurosurgery residents. At present, a prototype of the device is being manufactured.
BACKGROUND: Several mechanisms contribute to the increased stroke rate of patients with atrial fibrillation (AF). We assessed the frequency of carotid artery stenosis in patients with AF and its relationship to stroke during aspirin or warfarin therapy. METHODS: Carotid ultrasonography was done in 676 patients with AF enrolled in the Stroke Prevention in Atrial Fibrillation Study to detect cervical carotid stenosis of 50% or more of the luminal diameter. The presence of carotid stenosis was correlated with patient features and subsequent stroke during a mean of 2.6 years of follow-up. RESULTS: In patients with AF who were older than 70 years, the frequency of carotid stenosis was 12% in men and 11% in women. Carotid stenosis was independently associated with systolic hypertension (relative risk, 2.4; P = .002), diabetes (relative risk, 1.8; P = .04), and tobacco use (relative risk, 1.8; P = .02). Carotid stenosis did not add significantly to prediction of stroke when analyzed with other clinical risk factors for stroke in patients with AF (relative risk, 1.3; 95% confidence interval, 0.5 to 3.6; P = .55). CONCLUSIONS: Carotid artery stenosis of 50% or more occurs in about 12% of elderly patients with AF, reflecting the substantial prevalence of hypertension and diabetes in these patients. Carotid stenosis was not usefully predictive of stroke in patients with AF who were given aspirin or warfarin. Routine ultrasonography to detect carotid stenosis does not appear warranted in patients with AF without previous symptoms of brain ischemia.
PURPOSE: This study evaluates the use of transcranial Doppler (TCD) ultrasound in assessing the changes experienced by the cerebral circulation during cardiopulmonary resuscitation (CPR) and compares it with measurements of internal carotid artery (ICA) flow rates (ultrasonic flow-meter measurements) and cerebral blood flow (CBF) (radioactive-microsphere measurements) in a porcine cardiac arrest model undergoing closed chest CPR. METHODS: Sixteen piglets were anesthetized and subjected to TCD monitoring, ICA flow-rate measurements, and CBF measurements during CPR following induction of ventricular fibrillation. A total of 14 comparisons between TCD and CBF measurements, and 36 comparisons between TCD and ICA flow measurements were performed. Correlations were determined using Pearson's method, and the validity of the correlation was determined using Bonferoni's adjusted probabilities. RESULTS: The correlation between mean cerebral blood flow velocity and mean total ICA flow rate was 0.67 (P < .01). The correlation between peak systolic blood flow velocity and CBF was 0.76 (P = .02). CONCLUSIONS: TCD can provide on-line information about cerebral perfusion during CPR.
Explore the source record for details and available documents.
A 72-year-old man had posturally induced syncopal episodes, followed by quadriparesis, coma, and death. Neuroimaging studies supported the clinical diagnosis confirmed by neuropathological findings.
The natural history of intracranial arterial stenoses remains relatively unknown. To monitor the progression of these lesions over time, the authors reviewed transcranial Doppler (TCD) laboratory reports at five hospitals for patients with angiographically documented intracranial arterial stenoses along the internal carotid artery distribution, and at least two TCD studies conducted more than 2 months apart. Twenty-two patients (19 men and 3 women; mean age, 64 years) with 29 stenoses were identified. The findings were compared to reproducibility data obtained from 11 age-matched control subjects with repeat TCD studies. During a mean follow-up period of 21 months, peak systolic flow velocities corresponding to the areas of stenosis increased in 9 arteries with lesions, and new collateral flow patterns, indicating further hemodynamic compromise distal to the lesions, developed in 2; one of the latter also had increased corresponding velocities. Thus, 10 (35%) arteries with lesions had TCD evidence of progression. Flow velocities remained the same in 13 (45%) stenotic vessels and dropped in 2 (7%). Findings were considered inconclusive for 4 lesions (14%). These findings suggest that intracranial arterial stenoses are dynamic lesions, and that they can evolve and cause further reductions of the arterial diameters after relatively short periods of time. TCD can noninvasively detect their hemodynamic effects.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
BACKGROUND AND PURPOSE: Significant delays often occur during the treatment of patients with acute stroke. Some of those delays occur in the hospital. We attempted to shorten inhospital treatment intervals by creating a rapid-response system, similar to that available for cardiac arrest, that would allow the stroke team to be available within a few minutes to care for stroke victims. METHODS: We connected all beepers (pocket pagers) of stroke team members to a common access number and instructed the emergency staff to activate that number immediately upon arrival of a stroke victim. We monitored the response time and treatment interval for patients who were treated after this system was activated (Code Stroke patients) during the first 3 months of its availability and compared the results to those of patients seen for similar reasons during the study period but without the use of Code Stroke (control patients). RESULTS: A total of 12 Code Stroke patients were available for analysis, representing 12% of all patients (n = 98) seen in the emergency department for ischemic stroke during the study period. The remaining 86 patients constituted the control group. The mean time to evaluation of a Code Stroke patient by a stroke team member was 4.8 minutes (range, 2 to 7 minutes), and the mean time to treatment institution was 30 minutes (range, 10 to 120 minutes). There were significant differences between the consultation intervals in the two groups (P < .05). There was only a trend of a difference between treatment institution intervals (P = .06). CONCLUSIONS: It is possible to shorten inhospital treatment delays by instituting rapid-response systems within individual institutions.
Explore the source record for details and available documents.
We report three patients who developed delayed (ie, more than a week after the injury) symptoms of vertebrobasilar ischemia following motor vehicle accidents. The patients all had angiographic evidence of vertebral artery dissection and, upon further evaluation, occult fractures of the second cervical vertebra that were not detected by simple cervical spine radiography and required polytomography or CT for diagnosis. Vertebral artery dissection can result from occult cervical spine fractures and may present with delayed symptoms of brain ischemia.
Explore the source record for details and available documents.
Two-hundred seventy consecutive patients with "unexplained cerebral ischemia" were studied with transesophageal echocardiography to determine the value of this test in identifying potential cardiac sources of cerebral embolism. The findings of this group were compared with those of 772 consecutive patients undergoing transesophageal echocardiographic evaluation for indications other than cerebral ischemia. This study also examined this group of patients with unexplained cerebral ischemia to determine differences in relation to underlying cardiac rhythm and patient age. Intracardiac thrombus, atrial septal aneurysm, patent foramen ovale, spontaneous left atrial contrast and protruding debris in the thoracic aorta were found more often in patients with unexplained cerebral ischemia. Wall motion abnormalities of the left ventricle, as well as mild to moderate valvular lesions including mitral valve prolapse, were found to be similar in both groups. Spontaneous left atrial contrast, as well as mild to moderate valvular abnormalities, were found more often in patients with atrial fibrillation (22% of the group with unexplained cerebral ischemia). However, the presence of intracardiac thrombus was no more frequent in patients with atrial fibrillation than in those with normal sinus rhythm. Patients aged > 50 years were found to have atrial fibrillation and larger left atrial size more often than their younger cohorts, as well as a greater incidence of valvular abnormalities and left ventricular wall motion abnormalities. Mitral valve prolapse was seen more frequently in the younger cohort of patients.
The evaluation of victims of ischemic stroke has evolved over the last few years, primarily as a result of the introduction of innovative, sensitive, and informative diagnostic procedures. The role of the neurologist appears to have been redefined as one in which the identification of the presumptive cause and mechanism of the stroke is one of the primary responsibilities. The trend towards classification of patients into stroke subtypes, based upon etiology and pathogenesis, has led to a shift in care to a more etiology-specific approach. The inclusion of results of ancillary tests in the criteria utilized for stroke subtype classification has expanded the neurologists' ability to ascertain the presumptive etiology of many strokes that in the past were considered of unknown etiology. This has also resulted in an apparent increase in the proportion of ischemic strokes presumably due to cardiogenic embolism. The impact of transesophageal echocardiography upon changes in the presumptive etiology of ischemic stroke is illustrated, underscoring the future collaboration of neurologists and cardiologists in the evaluation of victims of presumed cardiogenic ischemic stroke.
A project to pursue standardization of the performance and interpretation of transcranial Doppler studies was designed. Phase I consisted of a national survey of the current practice of transcranial Doppler in the United States. From 200 ultrasound laboratories surveyed about the use of transcranial Doppler, 60 completed questionnaires were returned. The results show that further standardization of transcranial Doppler performance and interpretation is necessary, and provide the foundation for phases II and III of the project.