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Biomedical subjects

R F Wilson

Publications and source records attributed to R F Wilson.

At least 163 records · Page 9Linked to original sources
PubMed1990

Hepatic parenchymal oxygen tension following injury and sepsis.

Hepatic blood flow and splanchnic oxygen consumption were measured in 16 injured (n = 6) or septic (n = 10) patients and compared with values in 16 normal volunteers. Sepsis and injury appeared to stimulate an increase in blood flow and oxygen utilization, with the highest levels observed in the septic group. Patients with sepsis exhibited a 72% and 60% increase in hepatic blood flow and splanchnic oxygen consumption, respectively, compared with normal volunteers. Application of these data to the Krogh-Erlang tissue model indicates that despite an increase in oxygen delivery to the splanchnic bed during sepsis, it becomes more sensitive to hypoxic/ischemic events compared with other patient groups. This is indicated by a reduced centrilobular and increased critical oxygen tension. The major factor responsible for this is the regional hypermetabolism present in sepsis. This analysis emphasizes the critical importance of maintaining oxygen transport in critically ill patients with sepsis.

Humans↗
PubMed1990

Oxygen saturation monitoring during endoscopy.

The role of monitoring during endoscopy is not clearly defined. We have prospectively investigated continuous arterial oxygen saturation (SaO2) monitoring in 326 patients undergoing upper endoscopy (EGD) and 90 undergoing colonoscopy. Automated blood pressure recording was evaluated in 278 of these patients. SaO2 desaturation (less than 90%) occurred in 17.8% of patients undergoing EGD and 12.9% undergoing colonoscopy. Systolic blood pressure abnormalities (greater than 200 or less than 90 mmHg) occurred in 19.8% of EGD patients and 19.6% of colonoscopy patients. Treatment based on these abnormalities was required in 4.3% of patients during EGD and 8.8% during colonoscopy. A history of pulmonary or cardiac disease predicted increased risk during colonoscopy, while cardiac disease and age 60 years or above predicted desaturation during EGD. Pulse oximetry and automated blood pressure monitoring was especially valuable during endoscopy in the elderly and patients with cardiac or pulmonary disease. It may be used as a guide to therapeutic intervention and to avert major cardiopulmonary complications.

Adolescent↗
PubMed1990

The relationship between the biochemical composition of dental plaque from both approximal and free smooth surfaces of teeth and subsequent 3-year caries increment in adolescents.

The biochemical composition of both types of plaque and the subsequent caries increment were investigated in 39 males aged 11-12 years at the time of plaque collection. The calcium concentration of free smooth-surface plaque was inversely related to both total and approximal 3-year DFS increment (p less than 0.01). A relationship between calcium concentrations in approximal plaque and subsequent caries was restricted to the 3-year increment on approximal surfaces (p less than 0.05). There was evidence for a direct relationship between caries increment and both magnesium and organic phosphorus concentrations in plaque on the free smooth surfaces only (p less than 0.05). In contrast, a direct relationship between total caries increment and both total and intracellular carbohydrate concentrations reached statistical significance for approximal plaque only (p less than 0.05). Regression analysis indicated that the combination of the calcium and inorganic phosphorus concentrations of free smooth-surface plaque and the intracellular carbohydrate concentrations of approximal plaque explained 40% of the variation in subsequent caries increment.

Adolescent↗
PubMed1990

Mineral and matrix contributions to rigidity in fracture healing.

The purpose of this study was to investigate the relationships among selected properties of fracture callus: bending rigidity, tissue density, mineral density, matrix density and mineral-to-matrix ratio. The experimental model was an osteotomized canine radius in which the development of the fracture callus was modified by electrical stimulation with various levels of direct current. This resulted in a range of values for the selected properties of the callus, determined post mortem at 7 weeks after osteotomy. We found that the rigidity (R) of the bone-callus combination obeyed relationships of the form R = axb, where x is the tissue density, mineral density, matrix density or the mineral-to-matrix ratio of the repair tissue. These are analogous to power-law relationships found in studies of compact and cancellous bone. The results suggest that fracture callus at 7 weeks after osteotomy in canine radius behaves more like immature compact bone than cancellous bone in its mechanical and physicochemical properties. The present study demonstrates the feasibility of developing non-invasive in vivo densitometric methods to monitor fracture healing, since models may be developed that can predict mechanical properties from densitometric data. Further studies are needed to develop a refined model based on experimental data on the mechanical and physicochemical properties and microstructure of fracture callus at different stages of healing.

Animals↗
PubMed1990

Effectiveness of ultrasonic files in the disruption of root canal bacteria.

The physical mechanisms of ultrasound, namely cavitation and acoustic streaming, generated by the Enac-Osada ultrasonic unit were investigated for effectiveness in disrupting Streptococcus mitis. In addition, the bactericidal effect of ultrasound in the presence of 2.5% sodium hypochlorite was examined. Bacterial suspensions were irradiated directly with ultrasound in simulated root canals, and the viability of bacteria was examined after growth on a blood agar medium under anaerobic conditions at 37 degrees C for 5 days. The results indicated that ultrasound per se failed to disrupt bacteria but resulted in increases in the viable counts; the former was considered to be because of the lack of cavitation and the latter because of the dispersal effects of acoustic streaming. The 2.5% sodium hypochlorite solution demonstrated powerful bactericidal activity.

Colony Count, Microbial↗
PubMed1990

Management of the injured colon: evolving practice at an urban trauma center.

The records of 239 patients surviving more than 24 hours with full-thickness intraperitoneal colonic injuries over a 7-year period were reviewed. During the first 3 years, 29% (31/106) of the patients were managed by primary repair without colostomy. In the next 4 years, almost twice as many patients, 56% (75/133), with similar colonic trauma were treated without fecal diversion (p less than 0.05). Although there was no difference in the mean Trauma Score in the patients with primary repair in the two time periods, the Injury Severity Score (mean +/- sd) in the patients without colostomy in the later periods was significantly higher (17.8 +/- 2.1 vs. 20.2 +/- 5.1) (p less than 0.001). No patient suffered because of the increased incidence of primary repairs. These patients had five abdominal abscesses and only one leak, whereas the patients with colostomy had 15 intraperitoneal abscesses. Because of the safety when primary repair is performed, more liberal use of primary colonic repair following penetrating trauma is warranted.

Abscess↗
PubMed1990

Factors affecting mortality rate with iliac vein injuries.

Over an 8-year period, 49 patients were treated for iliac vein injuries with 25 (51%) deaths. The iliac vein injuries and their mortality rates (MR) were: common iliac vein--40% (6/15), internal iliac vein--65% (9/14), external iliac vein--29% (4/14), and two or more iliac veins--100% (6/6). This MR (51%) was much higher than those (18% to 38%) found in other series. The factors associated with this significantly increased MR were: Trauma Score less than 11 (MR = 71% or 24/35), initial OR systolic BP less than 70 mm Hg (MR = 89% or 15/17), ISS greater than 28 (MR = 65% or 24/37), 10 or more units of blood in the first 24 hours (MR = 65% or 22/34), and no obtainable BP on admission to the ED (MR = 65% or 15/22). Although the overall calculated probability of survival (Ps) by TRISS methodology was 0.43, several deaths might have been prevented by more complete resuscitation including restoration of core temperature above 34 degrees or 35 degrees C, and by packing the pelvis and closing rather than allowing three or more separate additional hypotensive episodes to occur while attempting definitive control of bleeding vessels.

Blood Pressure↗
PubMed1990

The management of flail chest injury: factors affecting outcome.

The records of 57 patients presenting with flail chest injury from 1981 through 1987 were reviewed to determine factors affecting morbidity and mortality. Fifteen patients (26%) had 8+ rib fractures with a unilateral flail and seven (12%) had multiple rib fractures with a bilateral flail. Thirty-two (56%) had moderate-severe pulmonary contusions and 44 (77%) required chest tubes for hemo-pneumothorax. Ventilatory assistance was used in 36 (63%). The major factors determining the need for ventilatory assistance were: an ISS greater than or equal to 23, blood transfusions in the first 24 hours, moderate-severe associated injuries (fractures, head injuries or truncal organs requiring operation), and shock on admission (p less than 0.001). An adverse outcome occurred in 15 (28%); nine required ventilatory assistance greater than or equal to 14 days and six died of sepsis with pneumonia. The main factors associated with an adverse outcome were: an ISS greater than or equal to 31 (p less than 0.001), moderate-severe associated injuries (p less than 0.001), and blood transfusions (p less than 0.005). Although the primary determinants of an adverse outcome were the associated injuries and blood loss, a bilateral flail (p less than 0.01) and age greater than or equal to 50 years (p less than 0.02) were contributing factors.

Adolescent↗
PubMed1990

A clinical and microbiological comparison of the effects of water and 0.02% chlorhexidine as coolants during ultrasonic scaling and root planing.

The maxillary teeth of 10 patients with moderately advanced chronic periodontitis were treated in a split-mouth design study. The baseline examination included plaque and bleeding scores, probing depths and probing attachment levels. 2 sites in each quadrant were selected for dark-field microscopic analysis. Each quadrant was randomly assigned to test or control and instrumented with an ultrasonic scaler using either 0.02% chlorhexidine or water as the coolant. Measurements were repeated 2, 6 and 10 weeks later, together with additional plaque sampling. Ultrasonic instrumentation with either chlorhexidine or water was equally effective in reducing bleeding scores and improving probing attachment levels. 42% of chlorhexidine- and 38.7% of water-treated sites showed gains of 1 mm or more in clinical attachment. Mean reductions in probing depth were similar (0.9 mm chlorhexidine, and 0.8 mm water). At the final examination, the chlorhexidine-treated quadrants had significantly more sites with probing depths in the 1-3 mm category and less in the greater than 3 mm category than the control quadrants (P less than 0.05). Both treatments reduced the microscopic counts of motiles and spirochaetes, resulting in a subgingival microbiota consistent with periodontal health. The results indicate that chlorhexidine has a slight adjunctive effect in the reduction of pocket depth when used as a coolant during ultrasonic root planing for the treatment of chronic periodontitis.

Adult↗
PubMed1990

Perfusion thallium imaging of type I diabetes patients with end stage renal disease: comparison of oral and intravenous dipyridamole administration.

Eighty patients with type I diabetes and end stage renal disease were prospectively evaluated for coronary artery disease with dipyridamole-thallium-201 scintigraphy and quantitative coronary angiography. Forty patients received dipyridamole orally, and 40 received it intravenously. The prevalence of coronary artery disease was 53%. There were no significant differences in the accuracy of the two dipyridamole tests (sensitivity = 85%, specificity = 85%, accuracy = 85% for the oral group; sensitivity = 86%, specificity = 72%, accuracy = 79% for the intravenous group). Combining the 80 patients into a single group gave a sensitivity of 86%, a specificity of 79%, and an accuracy of 83% for the detection of coronary disease. Although the accuracy of this test in this patient population was similar to that previously reported for other groups, the prevalence of disease was high and resulted in a low predictive value of a negative test (83%).

Administration, Oral↗
PubMed1990

Relationships between the biochemical composition of both free smooth surface and approximal plaque and salivary composition and a 24-hour retrospective dietary history of sugar intake in adolescents.

The relationships between the composition of both free smooth surface and approximal plaque and salivary composition and sugar intake assessed from a retrospective 24-hour dietary history were investigated. The inorganic phosphorus concentrations of both types of plaque collected from the permanent dentition were directly related to concentrations in stimulated whole saliva of 45 males aged 12-13 years. The calcium, inorganic phosphorus, water-soluble carbohydrate and protein concentrations of free smooth surface plaque were related to both the time since the last reported sugar intake and the amount of sugar and number of sugar intakes consumed in the previous 24 h as assessed from the retrospective diet histories of 75 females aged 14-15 years. A similar relationship with the reported time since sugar was observed for the calcium and carbohydrate concentrations in approximal plaque, but an association with the reported 24-hour sugar intake was not observed. Fewer statistically significant correlation coefficients were observed between the composition of both types of plaque and the reported sugar intake in the male subjects. The results indicate that the composition of both types of plaque are related to the composition of saliva and the time elapsed since the last sugar intake, but the relationship between the composition of plaque and sugar intake may differ between free smooth surface and approximal plaque.

Adolescent↗
PubMed1990

Interstudy variability of coronary flow reserve. Influence of heart rate, arterial pressure, and ventricular preload.

To define the long-term variability of serial coronary flow reserve (CFR) measurements in humans and to evaluate the influence of changes in heart rate, mean arterial pressure, and left ventricular preload on CFR, 45 patients with normal left ventricular function (38 cardiac allograft recipients, five patients with normal coronary arteries, and two patients with minimal coronary artery disease [less than 50% diameter stenosis]) were studied. CFR (ratio of peak hyperemic [h] to resting [r] coronary blood flow velocity [CBFV]) was measured with a 3F coronary Doppler catheter and intracoronary papaverine. Initial CFR measurements were highly correlated with repeat measurements obtained 11 +/- 0.6 months later (r = 0.95; mean absolute difference, 0.3 +/- 0.1; n = 17). Differences in CFR between studies were related to changes in heart rate (r = 0.61, p = 0.01) but not to changes in mean arterial pressure (r = 0.25, p = 0.33). To define the effects of rapid changes in heart rate, mean arterial pressure, and preload on CFR, these variables were altered by atrial pacing, handgrip exercise, and volume expansion, respectively. Atrial pacing produced a rate-related increase in rCBFV but did not change hCBFV. Consequently, CFR was significantly reduced as heart rate was increased progressively from 76 +/- 2 in sinus rhythm (4.5 +/- 0.2) to 100 (3.8 +/- 0.2, p less than 0.05, n = 32) to 120 beats/min (3.2 +/- 0.1, p less than 0.05, n = 7). Despite a 19 +/- 2 mm Hg rise in mean arterial pressure during handgrip exercise, CFR was unchanged from baseline (3.7 +/- 0.3 vs. 3.7 +/- 0.4, p = NS, n = 7) because rCBFV rose proportionally with hCBFV. When pulmonary capillary wedge pressure was increased from 9 +/- 1 to 16 +/- 1 mm Hg after volume expansion, CFR was significantly decreased (from 3.8 +/- 0.2 to 2.9 +/- 0.2, p less than 0.05, n = 9) because rCBFV was increased while hCBFV remained unchanged. Hence, serial CFR measurements in humans are highly reproducible in the absence of conditions known to affect resting or hyperemic coronary blood flow. Increases in heart rate or preload reduced CFR because rCBFV was increased while hCBFV was unchanged. In contrast, changes in mean arterial pressure did not alter CFR. Proper interpretation of CFR measurements should take into account the hemodynamic conditions at which they are obtained.

Blood Pressure↗
PubMed1990

Effects of adenosine on human coronary arterial circulation.

Adenosine is a potent vasodilator used extensively to study the coronary circulation of animals. Its use in humans, however, has been hampered by lack of knowledge about its effects on the human coronary circulation and by concern about its safety. We investigated in humans the effects of adenosine, administered by intracoronary bolus (2-16 micrograms), intracoronary infusion (10-240 micrograms/min), or intravenous infusion (35-140 micrograms/kg/min) on coronary and systemic hemodynamics and the electrocardiogram. Coronary blood flow velocity (CBFV) was measured with a 3F coronary Doppler catheter. The maximal CBFV was determined with intracoronary papaverine (4.5 +/- 0.2.resting CBFV). In normal left coronary arteries (n = 20), 16-micrograms boluses of adenosine caused coronary hyperemia similar to that caused by papaverine (4.6 +/- 0.7.resting CBFV). In the right coronary artery (n = 5), 12-micrograms boluses caused maximal hyperemia (4.4 +/- 1.0.resting CBFV). Intracoronary boluses caused a small, brief decrease in arterial pressure (similar to that caused by papaverine) and no changes in heart rate or in the electrocardiogram. The duration of hyperemia was much shorter after adenosine than after papaverine administration. Intracoronary infusions of 80 micrograms/min or more into the left coronary artery (n = 6) also caused maximal hyperemia (4.4 +/- 0.1.resting CBFV), and doses up to 240 micrograms/min caused a minimal decrease in arterial pressure (-6 +/- 2 mm Hg) and no significant change in heart rate or in electrocardiographic variables. Intravenous infusions in normal patients (n = 25) at 140 micrograms/kg/min caused coronary vasodilation similar to that caused by papaverine in 84% of patients (4.4 +/- 0.9.resting CBFV). At submaximal infusion rates, however, CBFV often fluctuated widely. During the 140-micrograms/kg/min infusion, arterial pressure decreased 6 +/- 7 mm Hg, and heart rate increased 24 +/- 14 beats/min. One patient developed 1 cycle of 2:1 atrioventricular block, but otherwise, the electrocardiogram did not change. In eight patients with microvascular vasodilator dysfunction (delta CBFV, less than 3.5 peak/resting velocity after a maximally vasodilating dose of intracoronary papaverine), the dose-response characteristics to intracoronary boluses and intravenous infusions of adenosine were similar to those found in normal patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine↗
PubMed1990

Hepatic blood flow and splanchnic oxygen consumption measurements in clinical sepsis.

In an effort to characterize the hemodynamic response of the liver to sepsis, hepatic blood flow (HBF) was measured in 10 normal volunteers and compared with that of 9 patients with sepsis. Flow was determined according to two different indicators and three methods of analysis including indocyanine green dye clearance (HBFICG), galactose clearance (GC), and galactose clearance with splanchnic galactose gradient measurement (HBFGG). For normal subjects, these three analytic methods provided essentially identical results (HBFICG = 0.74 +/- 0.18, GC = 0.72 +/- 0.14, and HBFGG = 0.76 +/- 0.16 L/min-m2). With hepatic venous sampling, HBF in patients with sepsis was significantly higher than normal levels (HBFICG = 1.28 +/- 0.50 and HBFGG = 1.17 +/- 0.52 L/min-m2) (p less than 0.025), but HBF by the GC technique (0.89 +/- 0.41 L/min-m2), which uses peripheral venous sampling, was not significantly increased because of reduced splanchnic galactose extraction, which appears to be characteristic of sepsis. Thus HBF estimates based on peripheral venous sampling must be interpreted with caution in view of the reduced extraction fraction in sepsis. HBF in clinical sepsis tends to increase in response to this inflammatory stress.

Galactose↗
PubMed1989

Identification of caries risk in schoolchildren: salivary buffering capacity and bacterial counts, sugar intake and caries experience as predictors of 2-year and 3-year caries increment.

Six variables which are capable of measurement at the chairside were assessed for their ability to identify children who would experience high caries increments during the subsequent 2 or 3-year period. The predictor variables measured in 84 urban schoolchildren, aged 11-12 years at baseline, were: baseline caries experience, salivary buffering power, counts of salivary Streptococcus mutans and lactobacilli, and two estimates of between-meal sugar intake. All the predictor variables showed statistically significant correlations with either 2-year or 3-year caries increment. Approximately 25% of subjects were identified as high risk individuals on the basis of a 2-year DFS increment of 5 and above, or a 3-year increment of 8 and above. None of the predictor variables achieved the target predictive value of 80%, either individually or in combination. The combination of Streptococcus mutans counts and buffering capacity measurements at baseline correctly identified low risk during the 3-year period in 78% of individuals (specificity), but only identified 12 out of 19 individuals (63%) at high risk (sensitivity), giving a predictive value of 75%. The predictive value for baseline caries experience was 66%. The results of the present study indicate that the salivary diagnostic tests have potential, but need further development before they can be used with confidence in clinical practice.

Buffers↗
PubMed1989

Intense microvascular constriction after angioplasty of acute thrombotic coronary arterial lesions.

Immediately after balloon dilation of a fresh thrombotic coronary lesion, 5 patients had angina, ST segment elevation, and a striking reduction of blood flow in the dilated artery. A mean (SEM) pressure gradient across the dilated lesion of only 3(1) mm Hg and an average minimum lesion diameter of 1.7 mm indicated that the decline in resting blood flow was not due to obstruction at the site of the original lesion. Neither distal vascular emboli nor side branch occlusions were visible on the angiogram. An increase in distal coronary artery pressure during a subsequent balloon inflation suggested that the site of vasoconstriction was distal to the origin of collateral vessels. The syndrome lasted 48-80 min and was not reversed with nitroglycerin or thrombolytic drugs. Papaverine lessened the syndrome transiently on one occasion. Such microvascular constriction, caused by release of potent vasoconstrictors from the clot, may partly explain the failure of emergency angioplasty to reduce infarct size in acute myocardial infarction.

Acute Disease↗
PubMed1989

Intra-abdominal sepsis following liver trauma.

Of 330 consecutive patients with liver trauma having a celiotomy over a 5-year period, 295 (89%) survived more than 72 hours. Of these 295, 35 (12%) developed sepsis, and 11 (31%) of these septic patients died. The sources of the sepsis in 30 of these patients included: abdominal abscesses--23, pneumonia or empyema--seven, acalculous cholecystitis--two, gangrene of right colon--two, and thigh abscess--one. In five other patients, the source of the sepsis was not found, even at autopsy. The mortality rate in the 30 patients with one or more identifiable foci of infection was 23%. In contrast, when the source of the sepsis could not be found, the mortality rate was 80% (4/5) (p less than 0.05). Factors associated with an increased incidence of abdominal abscess included: splenectomy, 75% (3/4); liver packs, 63% (5/8); 20+ units of blood, 57% (8/14); Class IV-V liver injury, 35% (8/23); 10-19 units of blood, 25% (7/28); colon injury, 19% (7/36); and open (Penrose) drainage of the abdomen, 11% (23/213). None of 82 patients without drains developed an intra-abdominal abscess. Thus early control of an identifiable source of infection provides the best results with sepsis following liver trauma. The most effective method for preventing intra-abdominal abscesses appears to be avoidance of drains in mild (Class I-II) liver injuries. The use of a closed system in the most severe injuries is still controversial and needs to be addressed in a prospective trial.

Abdomen↗