Search PubMed⌕ Search

Biomedical subjects

J R Richards

Publications and source records attributed to J R Richards.

At least 19 recordsLinked to original sources
PubMed1999

Lung injury from intratracheal and inhalation exposures to residual oil fly ash in a rat model of monocrotaline-induced pulmonary hypertension.

A rat model of monocrotaline (MCT)-induced pulmonary injury/hypertension has been recently used in particulate matter (PM) health effects studies, however, results have been equivocal. Neither the mechanism by which mortality occurs in this model nor the variation in response due to differences in PM exposure protocols (i.e., a bolus dose delivered intratracheally versus a similar cumulative dose inhaled over three days) have been fully investigated. Sprague Dawley rats (SD, 60 d old; 250-300 g) were injected with either saline (healthy) or MCT, 60 mg/kg, i.p. (to induce pulmonary injury/hypertension). Ten days later they were exposed to residual oil fly ash (ROFA), either intratracheally (IT; saline, 0.83 or 3.33 mg/kg) or by nose-only inhalation (15 mg/m3 x 6 h/d x 3 d). Lung histology, pulmonary cytokine gene expression (0 and 18 h postinhalation), and bronchoalveolar lavage fluid (BALF) markers of injury were analyzed (24 and 96 h post-IT; or 18 h post-inhalation). Data comparisons examined three primary aspects, 1) ROFA IT versus inhalation effects in healthy rats; 2) pulmonary injury caused by MCT; and 3) exacerbation of ROFA effects in MCT rats. In the first aspect, pulmonary histological lesions following ROFA inhalation in healthy rats were characterized by edema, inflammatory cell infiltration, and thickening of alveolar walls. Increases in BALF markers of lung injury and inflammation were apparent in ROFA-IT or nose-only exposed healthy rats. Increased IL-6, and MIP-2 expression were also apparent in healthy rats following ROFA inhalation. In regards to the second aspect, MCT rats exposed to saline or air showed perivascular inflammatory cell infiltrates, increased presence of large macrophages, and alveolar thickening. Consistently, BALF protein, and inflammatory markers (macrophage and neutrophil counts) were elevated indicating pulmonary injury. In regards to the third aspect, 58% of MCT rats exposed to ROFA IT died within 96 h regardless of the dose. No mortality was observed using the inhalation protocol. ROFA inhalation in MCT rats caused exacerbation of lung lesions such as increased edema, alveolar wall thickening, and inflammatory cell infiltration. This exacerbation was also evident in terms of additive or more than additive increases in BALF neutrophils, macrophages and eosinophils. IL-6 but not MIP-2 expression was more than additive in MCT rats, and persisted over 18 h following ROFA. IL-10 and cellular fibronectin expression was only increased in MCT rats exposed to ROFA. In summary, only the bolus IT ROFA caused mortality in the rat model of lung injury/hypertension. Exacerbation of histological lesions and cytokine mRNA expression were most reflective of increased ROFA susceptibility in this model.

Administration, Inhalation↗
PubMed1999

Intravenous urography in the emergency department: when do we need it?

Intravenous urography (IVU) is a useful radiographic study in the detection of renal and ureteral calculi. However, it is time consuming, expensive, and exposes the patient to i.v. contrast and radiation. To determine the impact of utilizing IVU less for the detection of renal calculi, criteria for ordering IVU in the emergency department (ED) were evaluated, and patients with high probability of positive IVU were identified. Variables included presence of acute flank pain with haematuria, prior history of renal calculus, degree of haematuria, and uncontrolled pain. We reviewed patients presenting with acute flank and abdominal pain with haematuria from May 1995 to May 1996 at a large urban university hospital. Charts were abstracted for prior history, reason for ordering IVU, time in the ED, laboratory results, IVU result, final diagnosis, and disposition. Data was analysed with Student's t-test, Wilcoxon rank-sum and receiver operating characteristic (ROC) analysis. A total of 302 patients were identified, and 185 underwent IVU during the study period. For patients with prior history of renal calculi 82% had positive IVU (sensitivity 51%, specificity 87%). For patients with both acute flank pain and haematuria, 92% had a positive IVU (sensitivity 93%, specificity 43%), and 19% of patients with abdominal pain of unclear aetiology with haematuria had a positive IVU. All patients with uncontrolled pain had evidence of high-grade obstruction on IVU. Degree of haematuria was not predictive of a positive IVU from ROC curve derivation. IVU is a useful study in the ED but may be overutilized, leading to lengthy patient stays. The combined objective findings of acute flank pain and haematuria are sensitive, and prior history is specific in identifying patients with renal calculi. Degree of haematuria was not useful in predicting renal calculi. By utilizing the criteria of acute flank pain and haematuria as a decision aid, 66% of all IVUs ordered could have been avoided.

Abdominal Pain↗
PubMed1999

Inappropriate use of emergency medical services transport: comparison of provider and patient perspectives.

OBJECTIVES: To determine the extent of inappropriate ambulance use from the perspectives of both emergency medical services (EMS) providers and patients utilizing EMS transport, assess level of agreement, and identify variables associated with inappropriate ambulance use. METHODS: A prospective cross-sectional study was done of a consecutive sample of patients arriving by ambulance during the month of February 1997 at an urban university hospital ED. EMS providers and patients completed a survey with questions regarding their perceptions of whether the need for ambulance transport was an emergency or a nonemergency. Patient demographic information and availability of alternate means of transportation to the hospital were also evaluated. RESULTS: Eight hundred eighty-seven patients were included in the study. EMS providers thought that 501 patient transports were appropriate and represented true emergencies, whereas 689 patients believed their medical problems were true emergencies. A significant number of patients (n=415, 47%) had access to alternative transportation to the hospital. Blunt traumatic injury and altered mental status were the most common reasons for EMS transport. Patient characteristics significantly associated with EMS provider perception of a true emergency were male gender, age >51 years, higher education, chest pain/cardiac complaints, shortness of breath/respiratory complaints, and Medicare insurance. Characteristics significantly associated with patients who perceived themselves to have true emergencies were black ethnicity, higher education, shortness of breath/respiratory complaints, and Medicare insurance. There was 75% agreement between EMS providers and patients on appropriateness of ambulance transport (kappa=0.84). CONCLUSION: Inappropriate ambulance use is a significant problem from both EMS provider and patient perspectives. Certain patient characteristics are associated with a higher probability of appropriate and inappropriate uses of EMS transport. A large number of patients transported by ambulance have alternative means of transportation but elect not to use them.

Adolescent↗
PubMed1999

Bowel and mesenteric injury: evaluation with emergency abdominal US.

PURPOSE: To assess emergency ultrasonography (US) for detection of bowel and mesenteric injury from blunt trauma. MATERIALS AND METHODS: For 3 years, prospective data on all patients undergoing emergency US were recorded. Patients with bowel and mesenteric injury were identified, and physical examination, laboratory, computed tomographic (CT), and intraoperative findings were compared with prospective data. RESULTS: From January 1995 to January 1998, emergency US was performed in 1,686 patients; 71 patients had bowel and mesenteric injury. Forty-one examinations were true-positive (i.e., with free fluid), and 30 were false-negative. Twenty-five of the 41 patients with true-positive US results had concomitant injuries that may have accounted for the free fluid, including liver, spleen, pancreas, gallbladder, kidney, and/or bladder injuries. The remaining 16 patients had isolated bowel and mesenteric injury. Bowel and mesenteric damage was identified intraoperatively in 70 patients. Twenty-nine of 30 patients with false-negative US examinations had abdominal tenderness. Sixteen patients with false-negative US results had bowel and mesenteric injury that was detected 12 or more hours after initial scanning. CONCLUSION: Free fluid in the abdomen is not detected in the majority of patients with isolated bowel and mesenteric injury. For clinical suspicion of bowel and mesenteric injury, observation, serial physical abdominal examination, and CT may be helpful in diagnosing this condition.

Adult↗
PubMed1999

Use of ultrasonography in the patient with acute renal trauma.

The purpose of this study was to assess the use of emergent ultrasonographic examination in acute traumatic renal injuries. Over a 3 year period, prospective data of all patients who had an emergency ultrasonogram were recorded. Thirty-two patients with 37 renal injuries were studied retrospectively to identify in how many patients the sonogram detected free fluid or a renal parenchymal abnormality. Free fluid in the abdomen was identified in 19 of 32 patients (59%). However, 12 of these 19 patients had concomitant injury, such as splenic rupture requiring splenectomy, severe liver lacerations, or bowel lacerations requiring repair, that were possible causes of the free fluid. Eliminating these patients, only seven of 20 patients with isolated renal injuries had free fluid in the abdomen (35%), whereas 13 of 20 patients (65%) had no evidence of free fluid. All seven patients with free fluid had moderate or severe renal injuries. Renal parenchymal abnormalities were identified on ultrasonograms in eight of 37 (22%) of injured kidneys. The abnormalities were detected more commonly in cases of severe injury (60%). In conclusion, acute injuries of the kidney from blunt abdominal trauma often are associated with significant splenic, hepatic, or bowel trauma. Isolated renal injuries frequently occur without the presence of free fluid in the abdomen. Furthermore, the ultrasonogram of the kidney often is normal with acute renal injuries, but it is more likely to be abnormal with severe (grade II or greater) renal injuries. Sonography may be used in the triage of patients with blunt abdominal trauma and possible renal injury. However, a negative ultrasonogram does not exclude renal injury, and, depending on clinical and laboratory findings, other imaging procedures such as computed tomography should be performed.

Abdominal Injuries↗
PubMed1999

Methamphetamine abuse and emergency department utilization.

Methamphetamine (MAP) abuse continues to increase worldwide, based on morbidity, mortality, drug treatment, and epidemiologic studies and surveys. MAP abuse has become a significant health care, environmental, and law enforcement problem. Acute intoxication often results in agitation, violence, and death. Chronic use may lead to infection, heart failure, malnutrition, and permanent psychiatric illness. MAP users frequently use the emergency department (ED) for their medical care. Over a 6-month period we studied the demographics, type, and frequency of medical and traumatic problems in 461 MAP patients presenting to our ED, which serves an area noted for high levels of MAP production and consumption. Comparison was made to the general ED population to assess use patterns. MAP patients were most commonly Caucasian males who lacked health insurance. Compared to other ED patients during this time, MAP patients used ambulance transport more and were more likely to be admitted to the hospital. There was a significant association between trauma and MAP use in this patient population. Our data suggest MAP users utilize prehospital and hospital resources at levels higher than the average ED population. Based on current trends, we can expect more ED visits by MAP users in the future.

Adult↗
PubMed1998

Computed tomography for blunt abdominal trauma in the ED: a prospective study.

A study was undertaken to determine the criteria for ordering abdominal computed tomography (CT) in the emergency department (ED) for stable patients who sustained blunt trauma and to identify a patient population at high risk for having intra-abdominal injury (IAI) utilizing physical examination, decrease in hematocrit, and hematuria. Patients in a university ED who had abdominal CT from April 1995 to October 1995 were evaluated prospectively. Before the scan, the examining physician completed an entry form that included physical findings, hematocrit, hematuria, Glasgow Coma Scale score, intoxication, distracting injuries, reasons for obtaining the scan, and planned disposition. Patients were followed until discharge. A total of 196 patients were evaluated. Abdominal tenderness was present in 120 patients. Twenty-two patients had IAI. Eight required surgical intervention, and all 8 had abdominal tenderness. A total of 40 potential trauma admissions were averted by obtaining CT within the ED. The combined abnormal abdomen examination and presence of hematuria had a sensitivity of 64%, specificity of 94%, positive predictive value of 56%, and negative predictive value of 95%. Decrease of > or = 5 in hematocrit was not statistically significant for detection of IAI. CT had no false negatives in this cohort. These results show that early CT scanning of stable patients who have sustained blunt trauma is an effective screen for IAI and may result in fewer total admissions, but has potential for overuse. Patients with abdominal pain and hematuria should be scanned. The benefit of a CT scan for patients without tenderness or with an isolated decrease in hematocrit is questionable.

Abdominal Injuries↗
PubMed1997

Computed tomography and blunt abdominal injury: patient selection based on examination, haematocrit and haematuria.

The criteria for ordering abdominal CT scans in the secondary survey of stable bluntly injured patients was examined. A patient population at high risk for having intra-abdominal injury (IAI) was identified by physical examination, a fall in haematocrit, and haematuria. A total of 444 patients receiving abdominal CT scans at a large urban trauma centre were reviewed. IAI was diagnosed in 49 (11 per cent), by radiographic and/or intra-operative findings. Abdominal tenderness was present in all 17 patients who underwent surgery. The sensitivity and specificity of abdominal CT scanning was 90 per cent and 99 per cent, respectively. The abdominal exam had a sensitivity of 63 per cent and a specificity of 65 per cent. A fall in haematocrit > or = 5 was not statistically significant. The combined abdominal exam and haematuria yielded a specificity of 93 per cent with a negative predictive value (NPV) of 93 per cent. Early CT scanning of stable patients who had sustained blunt injuries is an effective screen for IAI. The benefit of a CT scan for patients without abdominal tenderness or with an isolated fall in haematocrit is questionable. Serial abdominal examinations should remain the most timely and cost-effective method for identifying IAI in stable patients. The specificity and NPV of abdominal tenderness combined with haematuria approaches that of CT.

Abdominal Injuries↗
PubMed1997

Emergency medicine in Vietnam.

The Socialist Republic of Vietnam is one of the poorest countries in the world. Recent economic developments, as the country attempts to start a market economy, have had a profound impact on its health care system. This report describes the state of prehospital and emergency medical care in Vietnam and possibilities for the future.

Emergency Medical Services↗
PubMed1997

Emergency medicine in Cuba: report from a country in isolation.

Cuba is one of the poorest countries of the world. For the past 34 years the United States has maintained an economic embargo against Cuba. Because of this, Cuba has not been able to share in advances in American medical technology, pharmaceuticals, or research. The country has also been abandoned by the former Soviet Union. Recent political developments have assured continuation of the embargo. This report describes the current state of prehospital and emergency medical care in Cuba, how the embargo has affected emergency services, and possibilities for the future.

Cuba↗
PubMed1997

Methamphetamine toxicity: treatment with a benzodiazepine versus a butyrophenone.

Patients with methamphetamine toxicity often present to the emergency department (ED) agitated, violent and psychotic. To determine the efficacy of a benzodiazepine versus a butyrophenone for chemical restraint we conducted a prospective, randomized study at a large urban university ED between January 1995 and January 1997. Patients were randomized to receive either lorazepam or droperidol intravenously. A 6-point sedation scale was devised, with 6 representing extreme agitation and 1 deep sleep. Sedation scores were recorded at time 0, 5, 10, 15, 30 and 60 min. Vital signs were recorded at time 0 and at 60 min. If sedation was inadequate, repeat dosages of each drug could be repeated at 30 min. Toxicology screen, ethanol and creatinine phosphokinase levels were obtained. A total of 146 patients were evaluated. Seventy-four patients received lorazepam and 72 received droperidol. Both drugs had similar sedation profiles at 5 min. Patients receiving droperidol had significantly improved sedation scores at times 10, 15, 30 and 60 min than lorazepam (p < 0.001). More repeat doses of lorazepam were given (26) than droperidol (6) at 30 min. Both drugs produced significant reduction in pulse, systolic blood pressure, respiratory rate, and temperature over 60 min. We conclude droperidol produces a more rapid and profound sedation than lorazepam for methamphetamine toxicity. Lorazepam is more likely to require repeat dosing than droperidol.

Adult↗
PubMed1997

Differential regulation of macrophage arginine metabolism: a proposed role in wound healing.

Nitric oxide (NO) and ornithine, products of NO synthase or arginase, respectively, have opposing biological activities. The effect of mediators of leukocyte activation and inhibition on arginine metabolism of resident mouse peritoneal exudate cells (MPEC) was determined. Factors that increased basal NO synthase activity, interferon (IFN)-gamma and lipopolysaccharide (LPS), decreased arginase activity in intact cells. Transforming growth factor (TGF)-beta1 decreased IFN-gamma-stimulated NO synthase activity and produced a reciprocal increase in urea and ornithine release. TGF-beta1 had no effect on the activity of these enzymes in LPS-stimulated MPEC. Corticosterone (Cort, 100 ng/ml) decreased the basal activity of both enzymes. However, Cort inhibited NO synthase activity and increased ornithine release in MPEC exposed to IFN-gamma or LPS. The difference between arginase activity in intact cells vs. that of cell lysates suggested intracellular inhibition of arginase activity. Products of NO synthase, NO and citrulline, were shown to inhibit MPEC arginase activity under maximal assay conditions. Intracellular pH was not altered by exposure of MPEC to LPS, IFN-gamma, TGF-beta, and Cort. This reciprocal change in arginine metabolism is proposed to be an important component of wound healing. Expression of NO synthase creates a cytotoxic environment that may be important to the early phase of wound healing. As wound healing progresses, increased arginase activity produces an environment favorable for fibroblast replication and collagen production.

Amino Acids↗