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Biomedical subjects

P J McManamon

Publications and source records attributed to P J McManamon.

10 recordsLinked to original sources
PubMed1992

Contrast nephropathy in patients with impaired renal function: high versus low osmolar media.

Prescription of low osmolar contrast to prevent nephrotoxicity in subjects with pre-existing renal impairment is costly and has not been clearly shown to be effective. We entered 249 subjects with a pre-contrast serum creatinine greater than 120 mumol/liter (1.35 mg/dl) having cardiac catheterization or intravenous contrast into a randomized controlled trial comparing high and low osmolar contrast. The outcome assessed was a rise in serum creatinine repeated 48 to 72 hours after contrast. A further 117 patients entered the non-randomized prospective arm of the study. In the randomized study the serum creatinine rose by at least 25% after contrast in 8 of 117 (6.8%) given high and in 5 of 132 (3.8%) given low osmolar contrast (P greater than 0.05, one-tailed 95% confidence interval for the difference 3 to 7.8%). More severe renal failure (greater than 50% increase in serum creatinine) after contrast was uncommon (3.4% with high and 1.5% with low osmolar contrast). A rise in serum creatinine after contrast was significantly associated with the severity of the pre-contrast renal impairment and the presence of diabetes mellitus, but not with type of contrast. Diabetics with a serum creatinine greater than 200 mumol/liter (2.25 mg/dl) pre-contrast had a highest risk of deterioration in renal function after contrast. We conclude that in patients with pre-existing renal impairment the incidence of contrast nephropathy was not significantly different comparing high osmolar and nonionic contrast. The potential benefit of nonionic contrast in moderate renal impairment is likely to be small, but trials in diabetics with severe renal impairment should be undertaken urgently.

Aged↗
PubMed1992

Nonionic low-osmolality versus ionic high-osmolality contrast material for intravenous use in patients perceived to be at high risk: randomized trial.

To determine the cost-effectiveness of selective use of nonionic low-osmolality contrast material, the authors randomly assigned 955 patients to receive high-osmolality and 1,158 to receive low-osmolality intravenous contrast material. All patients had one or more of the following perceived risk factors for adverse reactions: prior reaction to contrast material, allergies, asthma, diabetes, cardiac or renal disease, anxiety, severe illness, and age greater than 50 years. The occurrence of any adverse event, need for therapy, or subjective symptoms was assessed in a double-blind fashion. An adverse reaction necessitating the attention of a physician occurred in 3.9% (n = 37) of patients in the high-osmolality and 0.9% (n = 10) of patients in the low-osmolality groups (P less than .000005). Therapy was administered to 1.4% (n = 13) and 0.5% (n = 6), respectively (P = .035). The difference was due to a reduction in urticaria and other mild anaphylactoid reactions. In a multivariate analysis, only prior reactions and allergy were independent risk factors. Selective use of intravenous nonionic contrast material is best justified in those with prior reactions, allergy, or asthma; at least 67% of reactions would be prevented.

Contrast Media↗
PubMed1990

The diagnosis and prognosis of autosomal dominant polycystic kidney disease.

BACKGROUND: Autosomal dominant polycystic kidney disease is usually caused by a mutant gene at the PKD1 locus on the short arm of chromosome 16, but in about 4 percent of families with the disorder it is caused by unknown mutations elsewhere in the genome. The natural course of the disease in both genetic forms is not well characterized. METHODS: We studied 17 families with autosomal dominant polycystic kidney disease to compare presymptomatic diagnosis by ultrasonography with diagnosis by genetic-linkage studies and to relate clinical variation of the disease to whether the PKD1 mutation was implicated. RESULTS: In 10 families the disorder was found to cosegregate with polymorphic DNA markers flanking the PKD1 locus, in 2 families it did not, and in 5 families linkage could not be determined. In the 10 families with the PKD1 mutation, 46 percent of the members less than 30 years old who had a 50 percent risk of inheriting a mutation had renal cysts, as compared with 11 percent of the members of the two families without linkage (P less than 0.001). In the PKD1 families, all 67 diagnoses made by ultrasonography were confirmed by determination of the genotype as inferred from linkage. Forty of 48 members (83 percent) less than 30 years old who inherited the PKD1 mutation had renal cysts. All 27 members 30 years old or older who inherited the mutation had renal cysts, suggesting that the probability of a false negative diagnosis did not exceed 0.13 in this age group (P less than 0.05). The mean (+/- SE) age at the onset of end-stage renal disease among members of the PKD1 families was 56.7 +/- 1.9 years, as compared with 69.4 +/- 1.7 years among members with cysts in the families without linkage (P = 0.0025). Hypertension and renal impairment were less frequent and occurred later in the families without the PKD1 mutation. CONCLUSIONS: At present, in most persons with a 50 percent risk of autosomal dominant polycystic kidney disease, imaging techniques are the only mode of reaching a diagnosis before symptoms appear. In such persons a negative ultrasonographic study during early adult life indicates that the likelihood of inheriting a PKD1 mutation is small. In the few who inherit a non-PKD1 mutation for polycystic kidney disease, renal failure is likely to occur relatively late in life.

Adult↗
PubMed1989

The cardinal manifestations of Bardet-Biedl syndrome, a form of Laurence-Moon-Biedl syndrome.

To determine the interfamilial and intrafamilial variation in the expression of the Bardet-Biedl syndrome (a form of Laurence-Moon-Biedl syndrome), we looked for the five recognized features of the disorder (retinal dystrophy, obesity, polydactyly, mental retardation, and hypogonadism), plus possible renal manifestations, in some or all of 32 patients with this disorder. All 28 patients examined had severe retinal dystrophy, but only 2 had typical retinitis pigmentosa. Polydactyly was present in 18 of 31 patients, but syndactyly, brachydactyly, or both were present in all. Obesity was present in all but 1 of 25 patients. Only 13 of 32 patients were considered mentally retarded. Scores on verbal subtests of intelligence were usually lower than scores on performance tasks. Seven of eight men had small testes and genitalia, which was not due to hypogonadotropism. All 12 women studied had menstrual irregularities, and 3 had low serum estrogen levels (1 of these had hypogonadotropism, and 2 had primary gonadal failure). The remaining women who were of reproductive age had endocrinologic evidence of reproductive dysfunction. Diabetes mellitus was present in 9 of 20 patients. Renal structural or functional abnormalities were universal (n = 21), and three patients had end-stage renal failure. We conclude that the characteristic features of Bardet-Biedl syndrome are severe retinal dystrophy, dysmorphic extremities, obesity, renal abnormalities, and (in male patients only) hypogenitalism. Mental retardation, polydactyly, and hypogonadism in female patients are not necessarily present.

Female↗
PubMed1989

Contrast material-induced renal failure in patients with diabetes mellitus, renal insufficiency, or both. A prospective controlled study.

To determine the risk of nephrotoxicity induced by the infusion of radiographic contrast material, we undertook a prospective study of consecutive patients undergoing radiographic procedures with intravascular contrast material. There were three study groups: patients with diabetes mellitus and normal renal function (n = 85), patients with preexisting renal insufficiency (serum creatinine level, greater than or equal to 150 mumol per liter) without diabetes (n = 101), and patients with both diabetes and renal insufficiency (n = 34). The control group consisted of patients undergoing CT scanning or abdominal imaging procedures without the infusion of contrast material who had diabetes mellitus (n = 59), preexisting renal insufficiency (n = 145), or both (n = 64). Clinically important acute renal failure (defined as an increase of greater than 50 percent in the serum creatinine level) attributable to the contrast material did not occur in nondiabetic patients with preexisting renal insufficiency or in diabetics with normal renal function. The incidence of clinically important contrast-induced renal failure among the diabetic patients with preexisting renal insufficiency was 8.8 percent (95 percent confidence interval, 1.9 to 23.7 percent), as compared with 1.6 percent for the controls. The incidence of acute renal insufficiency, more broadly defined as an increase of greater than 25 percent in the serum creatinine level after the infusion of contrast material, was 11.8 percent among all patients with preexisting renal insufficiency. After the exclusion of patients whose acute renal insufficiency could be attributed to other causes, the incidence was 7.0 percent (95 percent confidence interval, 3.2 to 12.8 percent), as compared with 1.5 percent in the control group. The risk of acute renal insufficiency attributable to the contrast material was therefore 5.5 percent, and the relative risk associated with the infusion of contrast material was 4.7. These rates were similar whether the osmolarity of the contrast material was high or low. We conclude that there is little risk of clinically important nephrotoxicity attributable to contrast material for patients with diabetes and normal renal function or for nondiabetic patients with preexisting renal insufficiency. The risk for those with both diabetes and preexisting renal insufficiency is about 9 percent, which is lower than previously reported.

Clinical Trials as Topic↗
PubMed1986

Audit of the Medical Audit Committee.

We reviewed 39 medical audits started in one institution between 1981 and 1985 to determine whether they monitored the quality of health care in a scientific manner, whether recommendations were made that could improve the quality of health care and, if so, whether the recommendations were acted on. Thirty-three audits (85%) were completed; 21 (64%) failed to state their objectives, 30 (91%) failed to compare their results with those in the literature, 9 (27%) made no recommendations that could improve the quality of health care, and 9 were poorly researched and written. The number of patients in each audit was usually adequate. Feedback was rarely received by the Medical Audit Committee concerning the Medical Advisory Committee's response to the audit. Information concerning the implementation of recommendations was available for 17 of the 24 audits that made recommendations; 7 (41%) had failed to implement half or more of the recommendations. Despite these problems, 8 (24%) of the audits were considered to be of a quality that could improve health care. We present recommendations to improve the audit procedure and foster the growing confidence among doctors in the medical audit.

Canada↗
PubMed1975

The pathogenesis of reflux nephropathy (chronic atrophic pyelonephritis).

The relationship between vesico-ureteric reflux and coarse renal scarring (atrophic pyelonephritis) has been studied in swine. Scars were observed to develop where reflux took place into the kidney substance via the renal papillae (intrarenal reflux). They were confined to these regions and were similar in size, distribution and other features peculiar to those found in the human from early childhood onwards. Intrarenal reflux was found to be related to the pressure within the urinary tract as well as to vesico-ureteric reflux. Infection was not an essential factor in scar-formation, but it appeared to intensify the scarring process. The histological findings were a progressive focal interstitial fibrosis confined to the zones of intrarenal reflux, extending from the capsule to the papillary tip, and varying in severity with pressure, time and the extent of intrarenal reflux. Nephron and tubular damage accompanied all grades of fibrosis, with the possible exception of the earliest. In many respects the histological changes closely resemble those due to obstruction, except they are focal in distribution. Added features are the early peripheral lymphocytic aggregations and interstitial fibrosis which appear to suggest that some "irritant"--possibly urine--reaches the interstitium and drains away via the lymphatic system. Many of the phenomena observed were strikingly similar to those present in children with the more severe grades of vesico-ureteric reflux. In some cases a mixture of generalized obstructive nephropathy and focal scarring developed; in others focal scarring took place with normal papillae elsewhere. The results are readily reproducible. The basic questions as to whether it is bladder pressure, or infection, or a mixture of the two which is responsible for scar-formation are discussed.

Adult↗
PubMed1974

Acute emphysematous cholecystitis.

Acute emphysematous cholecystitis is an uncommon condition caused by gas-forming organisms and characterized by the presence of gas in the wall and lumen of the gallbladder. Its incidence is higher among male diabetics. AEC in an elderly North American diabetic man with Indian ancestry is reported with a brief review of the world literature. The diagnosis was made preoperatively with the aid of plain radiographic films of the abdomen. A gangrenous distended gallbladder was removed at operation. Clostridium perfringens was cultured from the gallbladder contents and wall. If AEC is suspected, intensive antimicrobial therapy and fluid and electrolyte replacement should be given prior to early surgical intervention.

Acute Disease↗