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Biomedical subjects

P Merrick

Publications and source records attributed to P Merrick.

7 recordsLinked to original sources
PubMed1993

Comparison of the 25-gauge Whitacre with the 24-gauge Sprotte spinal needle for elective caesarean section: cost implications.

Spinal anaesthesia provides rapid, safe anaesthesia for Caesarean section. The pencil-point spinal needles (Sprotte and Whitacre) are reported to have a low incidence of post-dural puncture headache (PDPH). As the 25G Whitacre is less expensive than the 24G Sprotte needle, this prospective, randomized, double-blind study was designed to compare the incidence of PDPH and ease of insertion of these needles in 304 ASA 1 and 2 women having elective Caesarean section under spinal anaesthesia. Each patient was assessed daily for five consecutive days following Caesarean section by an investigator blinded to the needle used. The results indicate that the two needles have a similar ease of insertion, number of failed insertions, and failed subarachnoid blockade. An inability to insert the spinal needles occurred in two patients in each group. Therefore, 150 patients in each group completed the study. The incidence of PDPH with the 24G Sprotte needle was 4.0% (6/150) compared with 0.66% (1/150) with the 25G Whitacre (NS). There was no correlation between the occurrence of PDPH and the difficulty of needle insertion, presence of transient hypotension or the effectiveness of anaesthesia delivered. This study indicates that both needles are comparable with respect to ease of insertion and incidence of PDPH. As the Whitacre needle is less expensive it is a reasonable alternative to the more expensive Sprotte needle.

Adult↗
PubMed1993

A modified retrobulbar block for eye surgery.

A modified retrobulbar block (MRB) using a single superomedial injection was compared with the classical retrobulbar block (RB) and peribulbar block (PB) in a randomized, prospective, surgeon-blinded study involving 150 patients undergoing cataract surgery. No serious complication occurred in any of the patients. The MRB produced higher rates of total akinesia in the orbicularis and all the extraocular muscles, which were statistically significant for the orbicularis, superior, inferior and lateral rectus and oblique muscles when compared with RB, and for the superior rectus and oblique muscles when compared with PB. MRB required less supplemental blocks, provided good operating conditions for the surgeon, and achieved high patient acceptance. It is concluded that MRB is a useful alternative method of ocular block for cataract surgery.

Adult↗
PubMed1983

Pharmacokinetics of metronidazole in patients undergoing peritoneal dialysis.

After a single 500-mg intravenous dose of metronidazole, plasma and dialysate levels were measured over a 7.5-h period in five patients undergoing peritoneal dialysis for terminal renal failure. Approximately 10% of this dose was removed by dialysis during that period, and therapeutic levels were maintained in plasma. No routine adjustment in the dosage of metronidazole appears necessary in patients undergoing peritoneal dialysis.

Adult↗
PubMedDate not supplied

Scanning electron microscopy of cultured human keratinocytes.

Cultured keratinocytes are used for wound coverage in some patients with extensive burns, but there are difficulties in assessing when the keratinocytes are ready for grafting. The morphologic characteristics of developing cultured skin provide a method of identifying mature grafts. This study investigated the structure of cultured keratinocytes (apical and basal cells) by means of Scanning Electron Microscopy. Both primary cultures and secondary-passage cultured keratinocytes were studied from subconfluence through maturity and into senescence. At subconfluence, the keratinocytes comprised one cell layer, contiguous in some areas, and appeared as irregular, polygonal cells with protruding nuclei. Contiguous cell membranes had microvillae that varied in pattern and length. With initial stratification (two layers), the apical cells were immature and had finger-like microvillae that projected from rounded cells. The basal cells were uniformly covered with short microvillae. Additional stratification (four to five cell layers) gave rise to an apical layer that resembled a quasi-stratum corneum in which cells lacked both cytoplasm and nuclei. Basal cells were plump and regular, with microvillae that protruded from intact cell membranes. These characteristics can be used as indicators of mature keratinocytes to optimize the take of keratinocyte grafts. At senescence, many basal cells were flattened and lacked part of their cell membrane. There are defects in the cultured keratinocyte cell sheet that would limit graft take. A comparison between primary culture and secondary passage noted that primary-culture cultured keratinocytes were less suitable for grafting purposes because of the variation in maturation rates between dishes that were plated at the same time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗