PubMed Health⌕ Search

Biomedical subjects

J H Meiring

Publications and source records attributed to J H Meiring.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of Allen's test in both arms and arteries of left and right-handed people.

The Allen's test as described in 1929 by Edgar V. Allen has been modified, adapted and complemented by other newer modalities but remains a first line standard test to evaluate the arterial supply of the hand. In this study an attempt has been made to add more information regarding the arterial supply of the hand, in left- and right-handed individuals, left and right hands and the ulnar and radial arteries, when doing the Allen's test. A modified Allen's test using an oxygen saturation monitor was used. The sample group consisted of 80 (30 left-handed and 50 right-handed) students. No significant differences between the Allen's test of the left and right hands in the left and right-handed individuals were found. There was a marginal but not significant difference between the two arteries. The ulnar artery took slightly longer to reach baseline values as compared to the radial artery. The results suggest that a positive Allen's test can be found in both left and right-handed people, with regard to the left and right hands and both radial and ulnar arteries may be implicated. This information should be kept in mind when selecting either the radial or ulnar artery for grafting purposes (e.g. coronary angiosurgery) and forearm artery cannulation.

Adult↗
PubMed2006

Anatomical considerations of the anterior approach for central venous catheter placement.

Central venous catheterization (CVC) entails the catheterization of the superior vena cava via either the subclavian or the internal jugular vein (IJV). This study looked at the frequency in which a needle was inserted into the IJV using the anterior CVC approach, which entails inserting the needle into the apex of Sedillot's triangle, formed by the sternal and clavicular heads of sternocleidomastoid (SCM). The ipsilateral distances from the apex of Sedillot's triangle to the superior aspect of the sternoclavicular joint and the diameter of the IJV were also measured. A needle was inserted into the apex of Sedillot's triangle in 36 adult cadavers with mean age of 62 +/- 19 years (mean +/- SD), mean height of 1.6 +/- 0.18 m, and a mean weight of 55 +/- 16 kg. Subsequent dissections of this area revealed the relation of the needle to the IJV. Results indicate that on the right, the needle was inserted into the IJV in 97.14% of the cases. On the left, the needle entered the IJV in 78.79% of the cases. From the sternoclavicular joint, the apex of Sedillot's triangle was found to be 40.87 +/- 1.62 mm and 38.73 +/- 6.34 mm on the right and left, respectively. The IJV diameter was 17.29 +/- 1.07 mm on the right and 15.30 +/- 0.25 mm on the left. We conclude that the anterior CVC approach is an anatomically accurate technique. It is furthermore important to realize that when performing any invasive procedure, a sound anatomical knowledge of the region is extremely important, as complications are often due to lack of understanding or misunderstanding of the relevant anatomy.

Adult↗
PubMed2006

Superficial radial nerve injury during standard K-wire fixation of uncomplicated distal radial fractures.

This study determines the incidence of superficial radial nerve injury after Kirchner wire insertion. An experienced orthopedic surgeon inserted the K-wires into the radii of 92 adult cadavers. Subsequent dissection of the area exposed the superficial radial nerve and any observed nerve injury was documented. It is clear from the results that nerve injury may still occur as a result of K-wire insertion; however, the current method of K-wire insertion still proves to be a reliable and safe procedure for fixation of distal radial fractures.

Bone Wires↗
PubMed2005

Mandibular landmarks as an aid in minimizing injury to the marginal mandibular branch: A metric and geometric anatomical study.

Iatrogenic injury to the marginal mandibular branch is an important reason for medicolegal actions. The aim of this study was to determine the distance of the marginal mandibular branch to the inferior border of the mandible as well as variation of nerve position in relation to this border. The marginal mandibular branch was dissected carefully in a number of 36 facial halves. Three points were identified on the inferior border of the mandibular ramus: Point A at the angle of the mandible, Point B just anterior to the facial artery, and Point C, 2 cm anterior to Point B. A metric and geometric morphometric analysis, including thin-plate spline and relative warp analysis was done to determine the variation of nerve position in relation to these three bony landmarks. The metric study indicated a median distance from Point A to the nerve 2.3 mm inferior to Point A, 2.4 mm superior to Point B, and 10.7 mm superior to Point C. The shape analysis indicated that variation in the position of the nerve occurs most commonly at Points A and B. We conclude that these mandibular landmarks may assist surgeons in minimizing marginal mandibular branch injury and patient discomfort.

Aged↗
PubMed2005

Easily identifiable bony landmarks as an aid in targeted regional ankle blockade.

Regional anesthesia around the ankle joint is well suited to a large number of surgical procedures of the foot. Previous studies have alluded to the variable nerve distribution of the foot, which may result in incomplete blocks. The aim of the study was to determine the position of the nerves in relation to the ankle joint to easily identifiable bony and prominent soft tissue landmarks to aid more accurate targeting of these nerves. A number of 94 ankles (47 left; 47 right) were dissected to expose the tibial, sural, deep fibular (peroneal), superficial fibular (peroneal), and saphenous nerves. The distance of the nerves relative to easy to find bony landmarks was measured. A distance (alpha) was measured from the middle of the tibial nerve to the most medial aspect of the medial malleolus. Measurement beta was considered from the inferior tip of the lateral malleolus to the anterior border of the sural nerve on a horizontal plane. Measurement delta was taken from the medial border of the deep fibular (peroneal) nerve to the most anterior aspect of the medial malleolus. epsilon was measured from the middle of the superficial fibular (peroneal) nerve to the most anterior aspect of the medial malleolus on a horizontal plane. The saphenous nerve was measured (gamma) from its medial border to the most anterior aspect of the medial malleolus on a horizontal plane. Factors such as sex, length, and ankle side were also analyzed concerning their influence on the position of the nerves. This study suggests that a greater degree of certainty may possibly be attained when palpable and easy to find bony landmarks are used to determine the position of the nerves around the ankle and ensure a simple to perform, predictable, and selectively targeted block.

Anesthetics, Local↗
PubMed2005

The Pretoria Bone Collection: a modern South African skeletal sample.

The Pretoria Bone Collection began with the inception of the Department of Anatomy and the Medical School at the University of Pretoria in August 1942. Since then the collection has grown from a student aid to a resource for research. In the year 2000, the Pretoria Bone Collection was reorganised. The research material was divided into skulls, complete postcranial and incomplete postcranial remains. The collection presently contains 290 complete skeletons, 704 complete skulls and 541 complete postcranial remains. This paper presents information on the composition of this collection and hopes to heighten both national and international awareness of the collection and research opportunities in South Africa.

Adolescent↗
PubMed2005

Anatomical considerations of the pediatric ilioinguinal/iliohypogastric nerve block.

BACKGROUND: The ilioinguinal/iliohypogastric nerve block is safe, effective and easy to perform in order to provide analgesia for a variety of inguinal surgical procedures in pediatric patients. A relatively high failure rate of 10-25% has been reported, even in experienced hands. The aim of this study was to determine the exact anatomical position of the ilioinguinal and iliohypogastric nerves in relation to an easily identifiable constant bony landmark, the anterior superior iliac spine (ASIS) in neonates and infants. The current ilioinguinal/iliohypogastric nerve block techniques were also evaluated from an anatomical perspective. METHOD: Dissections were performed on a sample of 25 infant and neonatal cadavers (mean weight = 2.2 kg; mean height = 45.6 cm). The distance from the ASIS to both the ilioinguinal and iliohypogastric nerves, on a line connecting the ASIS to the umbilicus was carefully measured using a digital caliper. Three techniques, commonly used in clinical practice, were simulated on the anatomical specimens. RESULT: The left and right ilioinguinal nerves were closer to the ASIS than previously described, i.e. 1.9 +/- 0.9 mm (mean +/- sd) and 2.0 +/- 0.7 mm, respectively. The mean distance from the left and right iliohypogastric nerves to the ASIS are 3.3 +/- 0.8 mm and 3.9 +/- 1.0 mm, respectively. CONCLUSIONS: We suggest that the high failure rate of the ilioinguinal/iliohypogastric nerve block in this age group could be due to lack of specific spatial knowledge of the anatomy of these nerves in infants and neonates. This cadaver-based study suggests an insertion point closer to the ASIS, approximately 2.5 mm (range: 1.0-4.9) from the ASIS on a line drawn between the ipsilateral ASIS and the umbilicus.

Cadaver↗
PubMed2004

Cricothyroidotomy: a clinical anatomy review.

The safe and successful performance of a cricothyroidotomy demands a working and yet specific knowledge of anatomy. An ignorance or misunderstanding of anatomy may result in failure or complications. The Educational Affairs Committee of the American Association of Clinical Anatomists has highlighted the importance of clinical anatomy for several invasive procedures. This review is building on their work and contribute further to the understanding of the anatomical framework, particularly the pitfalls and complications related to performing a cricothyroidotomy.

Cricoid Cartilage↗
PubMed2004

Lumbar puncture: anatomical review of a clinical skill.

The safe and successful performance of a lumbar puncture demands a working and specific knowledge of anatomy. Misunderstanding of anatomy may result in failure or complications. This review attempts to aid understanding of the anatomical framework, pitfalls, and complications of lumbar puncture. It includes special reference to 3D relationships, functional and imaging anatomy, and normal variation. Lumbar puncture is carried out for diagnostic and therapeutic purposes. Epidural and spinal anesthesia, for example, are common in obstetric practice and involve the same technique as diagnostic lumbar puncture except that the needle tip is placed in the epidural space in the former. The procedure is by no means innocuous and anatomical pitfalls include inability to find the correct entry site and lack of awareness of structures in relation to the advancing needle. Headache is the most common complication and it is important to avoid traumatic and dry taps, herniation syndromes, and injury to the conus medullaris. With a thorough knowledge of the contraindications, regional anatomy and rationale of the technique, and adequate prior skills practice, a lumbar puncture can be carried out safely and successfully.

Adult↗
PubMed2004

Evaluation of clinical relevance of a problem-orientated head and neck module.

Current trends in medical education focus on outcomes-based learning as a means to facilitate student learning. The aim of this study was to evaluate a clinically applied module in head and neck anatomy for third-year dental students. The module linked clinical examination, regional dental blocks simulated on cadaver specimens, radiographic images and clinical case scenarios. A Likert-type questionnaire, completed by all students (n = 49), was used to evaluate student perceptions of this module objectively. The results indicate that an average number of students found that clinical examination received sufficient time (mean: 2.98) during the module, while a substantial number of students agreed that the integration of dental procedures stimulated them to study specific regional anatomy (mean: 3.82) and increased their interest in their future careers as dentists (mean: 4.04). The radiographs improved their understanding of anatomy (mean: 3.41) while the clinical case studies were a positive learning experience (mean: 3.10). The majority of students (mean: 4.12) felt that they were continuously made aware that they were studying appropriate matter for their future work as dentists. It seems evident that the integration of clinically relevant content facilitates and encourages the understanding of anatomy.

Anatomy↗
PubMed2003

Finding an ideal site for intraosseous infusion of the tibia: an anatomical study.

Intraosseous infusion is a technique used for the administration of fluids to a hemodynamically shocked child in whom attempts to access the vascular system have been unsuccessful. Although few complications are seen, injury to the epiphyseal growth plate during the performance of this technique remains a serious problem. This study investigates the relationship between the site of insertion of the intraosseous needle and the epiphyseal growth plate, and the ease of needle insertion into various locations of the tibia in newborn infants. Fourteen newborn infant cadavers (28 tibias in total) were dissected after placement of four needles: 1). through the tibial tuberosity (Site A); 2). 10 mm distal to the tibial tuberosity (Site B); 3). 20 mm distal to the tibial tuberosity (Site C) and; 4). 10 mm proximal to the tibial tuberosity (Site D). Distances from the distal end of the epiphyseal growth plate were measured. A high number of needle placements at Site A were inserted into the epiphyseal growth plate. Most placements at Site B were between 10 and 16 mm from the epiphyseal growth plate on the right side and between 10 and 15 mm on the left side, and all were inserted without difficulty. Although far from the epiphyseal growth plate, most placements at Site C were very difficult to insert because of the thick cortical bone. All placements at Site D entered the epiphysis or the epiphysis and joint space of the knee. An insertion site of at least 10 mm distal to the tibial tuberosity is therefore recommended to avoid epiphyseal growth plate injury and ensure ease of insertion.

Cadaver↗
PubMed2002

Clinical anatomy as the basis for clinical examination: development and evaluation of an Introduction to Clinical Examination in a problem-oriented medical curriculum.

Clinical anatomy is usually defined as anatomy applied to patient care. The question is asked whether students of a new horizontally and vertically integrated medical curriculum recognize the subject as the basis for clinical examination. A clinical anatomy practicum was developed in the special activity, "Introduction to Clinical Medicine," held in the second year of the Pretoria medical curriculum. The practicum was conducted on a station basis to anatomically prepare the student for the inspection, palpation, percussion, and auscultation of the cardiovascular, respiratory, abdominal, and urogenital systems. A total of 23 stations consisting of eight cardiovascular, seven respiratory, and eight abdominal/urogenital stations were designed. Standardized patients, cadavers, skeletons, prosected specimens, x-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI), multimedia programs, and clinical case studies were used as resources. A Likert-type questionnaire was used for student evaluation of the practicum. Most students realized the importance of surface anatomy for a family physician. More than two-thirds thought the practicum improved their understanding of the anatomical basis for clinical examination. The minority of students were stimulated to do further reading on clinical examination. The students' response to their ability to integrate the clinical examination with the radiological anatomy was average. Most students were continuously aware of the appropriateness of the practicum for their future career. We conclude that medical students recognize the importance of anatomy as the basis for clinical examination when exposed to an appropriate integrated presentation format.

Anatomy↗
PubMed2002

An assessment of the health status and physical characteristics of an early 20th century community a + Maroelabult in the north west province, South Africa.

As a result of mining activities, two related graveyards dating from the last decade of the 19th century and first half of the 20th century had to be relocated. This provided the opportunity to study 47 skeletons of black South Africans, with the aim of obtaining information on the health status and life style of people from a rural area in a mostly pre-antibiotic era. Although the sample is too small to do a proper palaeodemographic analysis, the age spread of the individuals indicates a high infant mortality rate and generally low life expectancy. Medical services were available, as could be seen from the surgically treated forearm fracture of one individual. One individual had signs of a possible treponemal infection, while subperiosteal bone growth on the ribs of another may indicate tuberculosis. High incidences of arthritic disease and joint degeneration probably indicate a high work load. Enlarged fontanelles with delayed closure were noted in some of the infants. Data on long bone lengths also indicate that the growth of the children may have been retarded in comparison to other similarly aged children. It thus seems as though this was a community under considerable stress. A surprising find was the unusually high incidence of individuals with dental abnormalities and variations.

Adolescent↗
PubMed2001

Evaluation of clinical relevance of problem-oriented teaching in undergraduate anatomy at the University of Pretoria.

Problem oriented medical curricula claim to be based on the fact that the clinical sciences facilitate and encourage the understanding of basic sciences. The question was asked whether the correlation of gross anatomy in the Abdomen Block in the new Pretoria medical curriculum, with clinically relevant content (i.e. relevant physical examination, imaging anatomy, clinical procedures, clinical presentations and clinical case studies) facilitates the understanding of human anatomy and enhances the development of the clinical thinking fundamental to clinical practice. The clinical anatomy component of the Abdomen Block (11 weeks duration) in the third year was developed by using standardized patients, cadaver material, skeletons, X-rays, CT scans, MRIs and multimedia programs. Student perceptions were assessed by a Likert scale questionnaire. Most students thought that integrating the physical examination enhanced their understanding of the relevant anatomy (mean: 3.55). A substantial number of students thought the clinical anatomy in the block laid a good foundation for imaging anatomy of the abdomen (mean: 3.41). The majority of students thought the clinical anatomy laid a good basis for the understanding of surgical procedures relevant to the abdomen (mean: 3.63). Students were mostly confident that clinical anatomy enhanced their understanding of clinical presentations (mean: 3.68). Although slightly fewer, the majority reckoned that the clinical case studies gave them a better understanding of the relevant anatomy (mean: 3.30). It seems evident that the integration of clinically relevant content facilitates and encourages the understanding of anatomy and thus aids in the development of clinical thinking.

Anatomy↗
PubMed2001

Variations of the position of the colon as applied to percutaneous nephrostomy.

The widespread and increasing usage of percutaneous nephrostomy procedures makes an awareness of the anatomical variations of the colon in relation to the kidney essential. Injury to the colon during this procedure is associated with significant morbidity. The aim of this study was to determine the relation of the colon to the insertion line used during a percutaneous nephrostomy and therefore determine whether the colon is at risk of injury. 333 CT-scans taken in a supine position were studied in order to determine the position of both the ascending and descending colon to the percutaneous nephrostomy insertion line on the level of the superior pole, hilum and inferior pole of the kidneys. In the majority of cases, the ascending and descending colon lie anterior to the line of insertion, and were therefore not at risk. However the descending colon was found to be at risk in 16.1% of cases and the ascending colon in 9.0% of cases on the level of the inferior pole of the kidney. The risk was significantly lower on the level of the hilum and superior pole of the kidneys on both sides. Age distribution analysis showed that the colon is rarely at risk under twenty years of age and the highest risk being in the age range above 40 years. Adequate radiographic evaluation is essential before performance of percutaneous nephrostomy procedures, especially to evaluate the position of the colon as related to the inferior poles of the kidneys.

Adolescent↗
PubMed1998

Abnormal origin of internal thoracic and vertebral arteries.

The aim of this study was to evaluate the variability of the origin of the internal thoracic and vertebral arteries after a cadaver demonstrated abnormal origins for both vessels. The arteries were studied in 60 adult cadavers and measurements taken to adjacent structures. In one cadaver the right internal thoracic artery originated from the third part of the subclavian artery (one of 120 arteries; 0.83%). The same cadaver presented with the left vertebral artery originating directly from the aortic arch between the left common carotid and left subclavian arteries. Two other cadavers also presented with abnormal vertebral arteries, making it three of 60 left vertebral arteries (5%). These results are comparable to the established range in the literature. The internal thoracic artery is used for revascularization in coronary artery diseases and as this area is also used for subclavian vein catheterization, it is important to be aware of this rare variation concerning the internal thoracic artery. This study reports an important variation in the origins of the internal thoracic and vertebral artery in a singular cadaver.

Adult↗
PubMed1997

Mandibular spine: a case report.

This is a brief review of the origin and normal variations of the genial tubercles, and specifically, a mandibular spine as an anatomical variation or abnormality. The case presented is that of abnormal genial tubercles observed during dissection of the floor of the mouth. A review and description on the morphology of the genial tubercles are given.

Aged↗