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Biomedical subjects

A Wyman

Publications and source records attributed to A Wyman.

At least 19 recordsLinked to original sources
PubMed1992

Effect of tissue pressure on contact laser insults.

The effect of variations in tissue pressure transmitted through contact laser probes during tissue ablation has been investigated. Weights of 10 and 50 g were transmitted through the tip of the probes onto the gastric and colorectal wall. At all laser energies the depth of tissue vaporization was significantly greater at the higher tissue pressure with perforation of the viscus occurring at laser energies above 10 J. The lateral zones of thermal tissue necrosis were not influenced by tissue pressure. Deformation of the wall of the viscus under the pressure of the probe was identified as a sign of excessive tissue pressure likely to result in perforation of any tissue of similar thickness to the normal gastric or colorectal wall.

Humans↗
PubMed1992

Preliminary evaluation of a new high power diode laser.

A high-powered semiconductor diode laser (805 nm) has recently been developed for medical use. The laser-tissue interactions of this wavelength have been compared with Nd:YAG (1064 nm). When used in the contact mode, the extent of tissue vaporization and zones of thermal necrosis produced by these two lasers were similar. The diode laser was also an effective and haemostatic laser scalpel. This compact laser unit has potential advantages over existing Nd:YAG lasers.

Animals↗
PubMed1992

Radical breast surgery with a contact Nd:YAG laser scalpel.

The use of a contact Nd:YAG laser scalpel during radical and modified radical mastectomy was evaluated in 18 patients with carcinoma of the breast. The laser scalpel performed well as a haemostatic tool, the associated mean blood loss for modified radical mastectomy being 132 ml. Operating time, operative blood loss, laser energy required and postoperative wound drainage were all related to patient obesity, correlating significantly with body weight and/or breast weight. The incidence of axillary seroma was not reduced by laser surgery and occurred in 53% of patients undergoing modified radical mastectomy. The Nd:YAG laser scalpel is an excellent haemostatic tool but it does not appear to have any other advantages over conventional surgery for mastectomy.

Adult↗
PubMed1991

Partial meniscectomy using the neodymium:YAG laser. An in vitro study.

We have evaluated, in an in-vitro study, the thermal effects of the neodymium:YAG (Nd:YAG) contact laser on meniscal tissue. There was no significant difference with regard to time taken to divide the meniscus or depth of necrosis between the two power settings used (25 and 30 W). A significantly greater (p less than 0.005) amount of energy, however, was expended at the higher power setting. The heat from the laser probe dissipated rapidly into the surrounding water without causing significant lateral thermal tissue damage. The Nd:YAG contact laser has features such as the ability to be transmitted through aqueous solutions, fiberoptic delivery, precise thermal tissue effects, and tactile feedback that would be beneficial in arthroscopic surgery. Although experimental, we suggest further clinical evaluation of its potential.

Humans↗
PubMed1991

Management of generalized faecal peritonitis--can we do better?

Generalized faecal peritonitis is associated with a mortality of over 50% in most series of cases. Despite great improvements in the standards of intensive care the morbidity and mortality associated with this condition have not improved, in part due to recurrent intra-abdominal sepsis. This preliminary study investigated the role of laparotomy, repeated abdominal lavage and debridement to determine whether such a policy might lead to an improvement in outcome. Of six cases studied three had perforated diverticular disease, two had Crohn's disease. Twenty lavages were performed on these six patients who had a mean ICU stay of 8 days. Five out of the six patients left hospital and remain well, one patient died of septicaemia and pre-existing renal failure. This study found that laparotomy, repeated abdominal lavage and debridement may be effective in reducing the morbidity and mortality of generalized faecal peritonitis and further study of this technique is appropriate.

Adult↗
PubMed1989

Intercostal blockade and pulmonary function after cholecystectomy.

Sixty-six patients undergoing cholecystectomy were randomly allocated to receive either intercostal blockade with bupivacaine supplemented with papaveretum or papaveretum alone for postoperative analgesia. Both groups were similar regarding distribution of sex, age, and weight. These two groups were compared. Patients who did not have intercostal blockade required postoperative analgesia sooner. There was no significant difference, however, in the total consumption of papaveretum. Both groups experienced similar degrees of pain, and there were no differences in postoperative pulmonary function. We conclude that although single intercostal blockade is an effective analgesic, it does not improve pain relief and does not improve pulmonary function after cholecystectomy when compared with a regimen of on-demand, intramuscularly administered papaveretum.

Analgesia↗
PubMed1987

What time of day should a urethral catheter be removed?

Patients who had undergone bladder neck surgery were randomized to having their urethral catheters removed either early in the morning or late at night. There was no difference in the incidence of urinary retention between these two groups of patients. However, patients who presented with acute urinary retention had a higher incidence of postoperative urinary retention. This study suggests that a urethral catheter may be safely removed in the evening without increasing the risk of urinary retention. There also seems to be no greater chance of the patient having to be recatheterized at an unsocial hour.

Aged↗
PubMed1986

Isolation of molecular probes associated with the chromosome 15 instability in the Prader-Willi syndrome.

Flow cytometry and recombinant DNA techniques have been used to obtain reagents for a molecular analysis of the Prader-Willi syndrome (PWS). HindIII total-digest libraries were prepared in lambda phage Charon 21A from flow-sorted inverted duplicated no. 15 human chromosomes and propagated on recombination-proficient (LE392) and recBC-, sbcB- (DB1257) bacteria. Twelve distinct chromosome 15-specific probes have been isolated. Eight localized to the region 15q11----13. Four of these eight sublocalized to band 15q11.2 and are shown to be deleted in DNA of one of two patients examined with the PWS. Heteroduplex analysis of two of these clones, which grew on DB1257 but not on LE392, revealed stem-loop structures in the inserts, indicative of inverted, repeated DNA elements. Such DNA repeats might account for some of the cloning instability of DNA segments from proximal 15q. Analysis of the genetic and physical instability associated with the repeated sequences we have isolated from band 15q11.2 may elucidate the molecular basis for the instability of this chromosomal region in patients with the PWS or other diseases associated with chromosomal abnormalities in the proximal long arm of human chromosome 15.

Chromosome Deletion↗