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Biomedical subjects

J M Porter

Publications and source records attributed to J M Porter.

At least 19 recordsLinked to original sources
PubMed2004

Representing older and disabled people in virtual user trials: data collection methods.

A database was developed to support the creation of a computer-based tool which will support design teams in evaluating the usability of a design during early prototyping and indicate which individuals are effectively excluded or designed out. Methods are described for the collection of multivariate data on 100 real individuals covering a range of physical characteristics and capabilities. These data were tested to ensure a breadth of representation of individuals (particularly older and disabled people) in terms of anthropometry, joint constraints, postural capabilities and task behaviours. The concept of the design tool itself is explored by conducting virtual user trials in the computer-aided design environment. The novel approach of the research encourages empathy with individual users and allows generic abilities, such as bending, reaching and lifting to be assessed.

Adolescent↗
PubMed2003

The efficacy of nicorandil, calcium chloride and nitroglycerin in treatment of ropivacaine-induced cardiotoxicity.

BACKGROUND AND OBJECTIVE: The amide-linked local anaesthetics, bupivacaine and ropivacaine, can cause depression of cardiac contractility and dysrhythmias. In a previous study, we observed decreased contractility and ST segment depression following ropivacaine administration in anaesthetized dogs. The efficacy of intravenous (i.v.) and intracoronary nicorandil (30 and 100 microg kg(-1)), i.v. nitroglycerin (glyceryl trinitrate) (5 microg kg(-1)) and calcium chloride (1, 2 and 4 mmol) in reversing the cardiotoxic effects of intracoronary ropivacaine were studied following the administration of intracoronary ropivacaine. METHODS: Six dogs were studied. The dogs were anaesthetized with i.v. pentobarbital (30 mg kg(-1)). A left-sided thoracotomy was performed and the left circumflex coronary was cannulated. For each dog, the dose of ropivacaine was identified, which produced measurable cardiotoxicity. In each case, ropivacaine was followed by one of the three resuscitation drugs. The effects of each resuscitation drug on ST segments and left ventricular contractility (dP/dt) produced by ropivacaine alone were compared with those produced by ropivacaine followed by each of the three resuscitation drugs using Fisher's exact test. RESULTS: The doses of ropivacaine required to produce depression of left ventricular dP/dt and ST segments ranged from 1 to 8 mg. Ropivacaine-induced depression of left ventricular contractility (dP/dt) was more rapidly and completely reversed by calcium chloride than by either nitroglycerin or nicorandil (P = 0.008). CONCLUSIONS: Calcium chloride may be effective in the treatment of inadvertent intravascular administration of amide local anaesthetic agents.

Amides↗
PubMed2002

The prevalence of musculoskeletal troubles among car drivers.

In order to explore the relationship between car driving and musculoskeletal troubles, a cross-sectional structured-interview survey of low- to high-mileage drivers (including individuals who drove as part of their job) was conducted based on the Nordic Musculoskeletal Questionnaire. The results clearly showed that exposure to car driving was associated with reported sickness absence due to low back trouble and that those who drive as part of their job appear to be more at risk from low back trouble than those whose jobs primarily involve sitting (not driving) and standing activities. The frequency of reported discomfort also increased with higher annual mileage. In addition, drivers of cars with more adjustable driving packages had fewer reported musculoskeletal troubles. This identifies an urgent need for the training of managers of fleet vehicles in the importance of developing measures to reduce this problem, for example, the selection of an individual's car with respect to comfort and postural criteria.

Adolescent↗
PubMed2001

Epidural ropivacaine hydrochloride during labour: protein binding, placental transfer and neonatal outcome.

This study was undertaken: (i) to quantify the effects of labour and epidural analgesia on plasma alpha1-acid glycoprotein concentration, (ii) to examine the effects of changes in plasma alpha1-acid glycoprotein concentration on plasma protein binding and placental transfer of ropivacaine, and (iii) to examine the association between umbilical venous ropivacaine concentration and neurobehavioural function in the neonate. Multiparous patients undergoing induction of labour received a continuous epidural infusion of 0.1% ropivacaine following an epidural bolus. A significant association was demonstrated between maternal plasma alpha1-acid glycoprotein concentration and 1/free fraction of ropivacaine 60 min after starting ropivacaine administration (r(2) = 0.77) but not at delivery. No significant correlation was demonstrable between maternal unbound ropivacaine concentration and either neonatal (cord) ropivacaine concentration or UV/MV (a measure of placental transfer). Thirty minutes after delivery, 9/10 neonates had neurological and adaptive capacity scores < 35, whereas only three infants had scores < 35 at 2 h. All scores exceeded 35 16 h after delivery. No association between mean (SD) umbilical venous ropivacaine concentration [0.09 (0.08) mg x l(-1)] and neurological and adaptive capacity scores was demonstrated.

Adult↗
PubMed2001

Optimizing duplex follow-up in patients with an asymptomatic internal carotid artery stenosis of less than 60%.

OBJECTIVES: The Asymptomatic Carotid Atherosclerosis Study established benefit of carotid endarterectomy for 60% to 99% asymptomatic internal carotid artery (ICA) stenosis. Optimal follow-up intervals to detect progression from < 60% to 60%-99% ICA stenosis are unknown. In a previous study from our laboratory, we found that ICAs with < 60% stenosis and peak systolic velocities (PSVs) of 175 cm/s or more on initial duplex were at high risk for progression. Prospective evaluation of this hypothesis and determination of optimal duplex follow-up intervals for asymptomatic patients with < 60% ICA stenosis form the basis of this report. METHODS: All patients who underwent initial carotid duplex examination for any indication since January 1, 1995, with at least one patent, asymptomatic, previously nonoperated ICA with < 60% stenosis; with 6 months' or greater follow-up; and with one or more repeat duplex examinations were entered into the study. On the basis of the initial duplex examination, ICAs were classified into two groups: those with a PSV less than 175 cm/s and those with a PSV of 175 cm/s or more. Follow-up duplex examinations were performed at varying intervals to detect progression from < 60% to 60%-99% ICA stenosis with criteria previously reported (both PSV > or = 260 cm/s and end-diastolic velocity > or = 70 cm/s). RESULTS: A total of 407 patients (640 asymptomatic ICAs with < 60% stenosis) underwent serial duplex scans (mean follow-up, 22 months). Three ICAs (0.5%) became symptomatic and progressed to 60%-99% ICA stenosis at a mean of 21 months (all transient ischemic attacks), whereas four other ICAs occluded without stroke during follow-up. Progression to 60%-99% stenosis without symptoms was detected in 46 ICAs (7%) (mean, 18 months). Of the 633 patent asymptomatic arteries, 548 ICAs (87%) had initial PSVs less than 175 cm/s, and 85 ICAs (13%) had initial PSVs of 175 cm/s or more. Asymptomatic progression to 60%-99% ICA stenosis occurred in 22 (26%) of 85 ICAs with initial PSVs of 175 cm/s or more, whereas 24 (4%) of 548 ICAs with initial PSVs less than 175 cm/s progressed (P <.0001). The Kaplan-Meier method was used to determine freedom from progression at 6 months, 12 months, and 24 months, which was 95%, 83%, and 70% for ICAs with initial PSVs of 175 cm/s or more versus 100%, 99%, and 95%, respectively, for ICAs with initial PSVs less than 175 cm/s (P <.0001). CONCLUSIONS: Patients with < 60% ICA stenosis and PSVs of 175 cm/s or more on initial duplex examination are significantly more likely to progress asymptomatically to 60%-99% ICA stenosis, and progression is sufficiently frequent to warrant follow-up duplex studies at 6-month intervals. Patients with < 60% ICA stenosis and initial PSVs less than 175 cm/s may have follow-up duplex examinations safely deferred for 2 years.

Adult↗
PubMed2001

Long-term functional outcome of neurogenic thoracic outlet syndrome in surgically and conservatively treated patients.

PURPOSE: Neurogenic thoracic outlet syndrome (NTOS) in the absence of bony and electrodiagnostic abnormalities, often referred to as disputed NTOS, remains enigmatic. Optimal treatment, especially the role of surgery, is controversial. The long-term functional outcome of a cohort of patients undergoing independent medical examination for disputed NTOS with symptoms sufficiently severe to cause inability to work forms the basis for this report. METHODS: Patients with disputed NTOS and symptoms sufficiently severe to cause at least temporary inability to work seen for independent medical examinations from 1990-1998 formed the study group. None of the patients were treated by our group. Functional outcome was assessed with information from a standardized telephone interview or patient questionnaire. The patients' ability to return to work and an assessment of their current level of symptoms and symptom progression since the time of onset were determined. RESULTS: Seventy-nine patients were reevaluated at a mean follow-up of 4.2 years (range, 2-7.5 years) after our initial evaluation. Fifteen patients (19%) underwent first rib resection surgery performed by others, whereas 64 (81%) had no surgery. Patients undergoing surgery had missed more work time than those undergoing conservative management (27.6 +/- 6.0 months vs 14.9 +/- 2.6 months, P <.04). Return to work was achieved in nine patients who were operated on (60%) and in 50 patients who were not operated on (78%) (P = not significant [NS]). Among operated patients, current assessment of symptom severity was severe, moderate, mild, and asymptomatic in 7%, 47%, 40% and 7%, respectively. This distribution did not differ significantly from that observed in nonoperated patients (11%, 55%, 30%, 5%; P = NS). When asked about changes in symptomatic status since onset, 7% of the operated group had complete resolution, 27% had marked improvement, 40% had minimal improvement, 13% had no improvement, and 13% were worse. This did not differ significantly from the change in symptoms reported by the nonoperated group (2%, 30%, 22%, 31%, 16%; P = NS). CONCLUSION: Most patients with disputed NTOS in this nonrandomized series were able to return to work and demonstrated an improvement of symptoms with long-term follow-up. First rib resection did not improve functional outcome in this group.

Adult↗
PubMed2001

Relationship between antiphospholipid antibodies and progression of lower extremity arterial occlusive disease after lower extremity bypass operations.

PURPOSE: Antiphospholipid antibodies (APLs), which consist of anticardiolipin antibodies (ACLs) or lupus anticoagulant (LA), are associated with venous thrombosis, stroke, and cardiac events. Although they are present in many patients with lower extremity atherosclerotic occlusive disease (LEAOD), the relationship between APL and the progression of LEAOD has not been reported. A comparison of progression of LEAOD as determined with direct imaging studies in patients with and without APL forms the basis for this report. METHODS: APL+ patients (immunoglobulin M [IgM] or IgA or IgG ACL > 3 SD units above control mean or positive LA) who underwent lower extremity bypass grafting between January 1990 and June 1999 (n = 79) were compared with an APL control group (n = 68). Members of the study and control groups were similar with respect to age, procedure, sex, length of follow-up, and multiple atherosclerosis risk factors. Progression of LEAOD was determined by comparing preoperative arteriograms with postoperative imaging studies (arteriograms or duplex scanning). External iliac, common femoral, superficial femoral and popliteal arteries were graded as < 50% stenosis, > or = 50% stenosis, or occluded. Posterior tibial and anterior tibial arteries were graded as patent or occluded. Progression was defined as any increase in stenosis category. RESULTS: The mean follow-up period was 31 months for APL+ and 35 months for APL- patients (P = not significant). Progression of LEAOD occurred in 58 (73%) of 79 APL+ patients and in 25 (37%) of 68 APL- patients (P <.001). There was no difference in progression in external iliac or common femoral arteries. Differences in progression were noted in more distal arteries; APL+ patients had significantly more progression in superficial femoral (45% vs 16%, P <.01), popliteal (31% vs 12%, P <.01), posterior tibial (29% vs 13%, P <.05), and anterior tibial arteries (29% vs 14%, P <.05). Multivariate logistic regression analysis showed a significant independent association between the presence of APL and progression of LEAOD (P <.0001). CONCLUSION: In this study, the presence of APL in patients undergoing lower extremity bypass operations was a significant independent risk factor for progression of LEAOD. We conclude that this patient group should be closely monitored in the postoperative period and appears ideally suited for prospective studies of therapies to modify LEAOD progression.

Aged↗
PubMed2001

Functional outcome after open repair of abdominal aortic aneurysm.

INTRODUCTION: Detailed information on functional outcome after open abdominal aortic aneurysm (AAA) repair is sparse. Information about functional outcome of open AAA repair is essential to allow comparison of treatment modalities. METHODS: To determine the functional outcome of patients after open repair of AAA, we reviewed 154 consecutive, nonemergency open repairs of infrarenal AAAs between 1990 and 1997 and each patient's medical records. Clinical variables were recorded for each patient, as were multiple outcomes, including ambulatory status, independent living status, current medical condition, and the patient's perception of recovery and satisfaction. Eighty-seven patients or their families were available for current telephone interview to obtain information about objective functional activities, including walking and driving, and subjective functional information, including assessment of complete recovery and willingness to undergo AAA repair again. Chart data were available for all 154 patients. RESULTS: There were 42 women and 112 men. A total of 139 operations were elective, and 15 were urgent. The operative mortality rate was 4%, mean hospital stay was 10.7 +/- 1.3 days, and mean intensive care unit stay was 4.57 +/- 1.17 days. Seventeen (11%) patients required transfer to a skilled nursing facility with a mean stay of 3.66 +/- 2.9 months. All patients were ambulatory preoperatively, whereas at last follow-up (median, 25 months; range, 0.13-108.5 months), 100 (64%) of the patients remained ambulatory, 34 (22%) required assistance, and 12 (14%) were nonambulatory. At current assessment by telephone interview, 33% of patients described a decrease in their functional activity including driving, shopping, and traveling compared with their preoperative status, whereas 67% were unchanged. When asked to assess their own degree of recovery, 64% of patients stated that they experienced complete recovery with an average time to recovery of 3.9 months, whereas 33% said they had not fully recovered at a mean follow-up of 34 months. Sixteen (18%) patients said they would not undergo AAA repair again knowing the recovery process, even though they appeared to fully understand the implication of AAA rupture. CONCLUSION: Patients undergoing open AAA repair generally experienced significant freedom from surgical complications. However, substantial functional impairment was present. It is unclear whether the functional disability resulted from the AAA surgery or from aging and comorbidities unrelated to surgery.

Activities of Daily Living↗
PubMed2001

Should trauma surgeons render definitive vascular repair in peripheral vascular injuries?

Our hypothesis is that in an established Level I trauma center general trauma surgeons should repair peripheral vascular injuries even in stable patients when there is time for a vascular consult. We reviewed all penetrating peripheral vascular injuries in stable patients operated on by nine experienced general trauma surgeons (1993-1996). Outcome measures were amputation, nerve damage, and vascular complications. There were 43 patients with 44 peripheral vascular injuries identified. Sixty per cent were from stab wounds. There were 27 arterial injuries (carotid four, subclavian one, vertebral two, axillary three, brachial eight, ulnar one, radial two, femoral five, and anterior tibial one). There were three venous injuries (one each subclavian, axillary, and popliteal). There were 14 combined injuries (vertebral two, femoral nine, and popliteal three). There were no mortalities. Morbidity was limited to patients with lower extremity injuries. In the nine patients with combined femoral vessel injury there were three complications (nerve damage, thrombosed arterial repair, and thrombosed venous repair). In the four patients with popliteal venous injuries there were two complications, both venous thrombosis. Our early arterial patency rate was 97.6 per cent. These data support the hypothesis that general surgeons with trauma experience can provide effective treatment of peripheral vascular injuries. The significance of these findings in improving the image of trauma surgery as a career is discussed.

Adolescent↗
PubMed2001

Digital rectal examination for trauma: does every patient need one?

The digital rectal examination is widely accepted as an essential component in the initial assessment of trauma. However, no data have been published that justify its routine use in all seriously injured patients. The objective of this study was to determine what if any impact on subsequent treatment and management decisions the initial digital rectal examination had on injured patients arriving at our emergency department (ED). We conducted a prospective observational study of all injured patients arriving at a Level II trauma center over a period of 6 months. A digital rectal examination was performed on all patients during the secondary survey phase of their initial evaluation shortly after arrival to the ED. The results of the rectal examination were noted for each patient with particular attention placed on the presence or absence of gross blood, Hemoccult result, prostatic examination, rectal vault integrity, and rectal sphincter tone. In addition the patient's hemodynamic parameters while in the ED and the injuries that were sustained were noted, as was their final disposition. Four hundred twenty-three patients were admitted to the ED after sustaining serious injuries. The mean Injury Severity Score was 9.96. The prostatic examination was normal in more than 99 per cent of patients; no high-riding or nonpalpable prostate glands were noted. Twenty-two patients (5.2%) were Hemoccult positive, but in none of these cases did the presence of occult blood in the stool lead to a change in the initial management or diagnostic approach. Three patients (0.7%) with penetrating injuries to the perineal/pelvic area had gross blood on digital rectal examination that prompted operative exploration to rule out a lower gastrointestinal injury. All three had rectal injuries confirmed at surgery. Rectal sphincter tone was normal in 406 (96%) patients, weak in 17 (4%), and absent in none. The only patient in whom the sphincter tone influenced management was an individual complaining of complete paralysis after a blunt mechanism of injury. He had normal rectal sphincter tone and admitted to malingering shortly thereafter. Overall the rectal examination influenced therapeutic decision making in five cases (1.2%). The digital rectal examination is unlikely to affect initial management when applied indiscriminately to all seriously injured patients during the secondary survey. Patients in whom the rectal examination may have a higher probability of influencing management are those with penetrating injuries in proximity to the lower gastrointestinal tract, questionable spinal cord damage, and severe pelvic fractures with potential urethral disruption or open fractures in continuity with the rectal vault. The Hemoccult test does not add useful information and should be discontinued as part of the secondary survey of injured patients.

Adult↗
PubMed2001

Trauma attending in the resuscitation room: does it affect outcome?

Although there are no Class I data supporting the regionalization of trauma care the consensus is that trauma centers decrease morbidity and mortality. However, the controversy continues over whether trauma surgeons should be in-house or take call from home. The current literature does not answer the question because in all of the recent studies the attendings who took call from home were in the resuscitation room guiding the care. We believe the correct question is: Does the presence of the trauma attending in the resuscitation room make a difference? At a university-affiliated Level II trauma center data from the trauma registry, resuscitation room flowsheet, and dictated admission notes were reviewed on all patients over a 6-month period. Data points were: attending present in the resuscitation room, standard demographics, resuscitation room time, time to operating room (OR), time to CT scan, length of stay, complications, and mortality. A total of 943 patients were studied with 216 (23%) having the attending present in the resuscitation room and 727 (77%) without the attending present. The groups were similar in terms of age, sex, Injury Severity Score, percentage Injury Severity Score greater than 15 (16-17.1%), and mechanism of injury (24-29% penetrating). Of all the data points studied only time to the OR had a statistically significance difference (P < 0.05) with it taking 43.8 minutes (+/-20.1) when the attending was present and 109.4 minutes (+/-107) when the attending was absent. There were also no missed injuries, delays to the OR, or inappropriate workups when the attendings were present. Only the time to the OR reached statistical significance. The time to the OR is indicative of the decision-making process in the resuscitation room, and it is in this area that the attendings' presence is the most useful. Also, we believe that it is important that there were no missed injuries, delays to the OR, or inappropriate workups when the attendings were present in the resuscitation room. This again speaks to the decision-making process. We believe that these data support the need for the attending to be present in the resuscitation room to facilitate accurate and timely decisions regardless of whether they take the call from home or in-house.

Adult↗