Biomedical subjects

D F Jimenez

Publications and source records attributed to D F Jimenez.

At least 37 records · Page 2Linked to original sources

PubMed1997

Cerebral vascular response to hypertonic fluid resuscitation in thermal injury.

The purpose of this project was to study the effects of various resuscitation fluid protocols in a systemically thermally injured rat sustaining 70% body surface area third degree burn using the pial window model in rats. The results show that there was a significant albumin leak in the cerebral vessels in both the experimental group which underwent no resuscitation fluid, as well as the experimental group that was resuscitated with Lactated Ringer's solution using the Parkland formula. When this was compared to the control group, as well as to the experimental group which received hypertonic hyperosmotic saline (HMS) boluses every hour, there was little if any leakage seen.

Animals↗

PubMed1997

Intrathecal morphine for postoperative analgesia following repair of frontal encephaloceles in children: comparison with intermittent, on-demand dosing of nalbuphine.

STUDY OBJECTIVE: To determine the efficacy of lumbar intrathecal (i.t.) morphine in a dose of 0.02 mg/kg in providing analgesia following repair of frontal encephaloceles. DESIGN: Prospective, open-label investigation of i.t. morphine with secondary comparison to a retrospective cohort. SETTING: Metropolitan hospital in the Philippines. PATIENTS: 24 ASA physical status I and II children undergoing frontal encephalocele repair. INTERVENTIONS: Following induction of general anesthesia. I.t. morphine (Group 1) was administered via single-shot technique or through a lumbar i.t. drain placed for cerebrospinal fluid drainage during the surgical procedure. Postoperative analgesia was assessed by visual analog score in patients greater than 5 years of age or a behavioral score in patients less than 5 years of age. The retrospective cohort received postoperative analgesia with intermittent doses of intravenous nalbuphine (Group 2). MEASUREMENTS AND MAIN RESULTS: Group 1 had decreased postoperative analgesic requirements, decreased intraoperative inhalational anesthetic requirements, and a longer time to the first request for postoperative analgesia than Group 2. The time to the first request for postoperative analgesia was 16.0 +/- 9.1 hours in Group 1 and 1.6 +/- 1.2 hours in Group 2 (p < 0.0001). Six of 12 patients in Group 1 required no analgesic drugs during the first 24 postoperative hours while all 12 patients in Group 2 (p = 0.02) did require analgesic drugs during this period. The patients in Group 1 who did not require supplemental analgesic drugs maintained pain scores of 2 or less throughout the first 24 postoperative hours. CONCLUSION: Lumbar IT morphine provides effective analgesia following repair of frontal encephaloceles in children and adolescents.

Analgesics, Opioid↗

PubMed1997

Anaesthetic management during awake craniotomy in a 12-year-old boy.

We present our approach to the preoperative preparation and anaesthetic management for awake craniotomy in a 12-year-old boy. Management included conscious sedation with a propofol infusion plus local anaesthetic infiltration of the scalp, periosteum, and dura. The complications which may be encountered during such procedures and their treatments are reviewed.

Anesthesia, Local↗

PubMed1997

Split-thickness calvarial grafts in young children.

Sixteen patients (mean age, 1.9 years) underwent split-thickness calvarial bone grafting using a full-thickness craniotomy, high-speed drill, and osteotomes for bone harvesting. The minimal calvarial bone thickness for a successful graft was found to be 7 mm. All patients were diagnostically studied preoperatively with computed tomographic scans and skull films. The mean follow-up was 2.9 years (range, 0.75-7.9 years). All patients had successful graft take. There were no infections or mortalities. Continued graft growth was seen in all patients. There was one dural tear during harvesting with no cerebrospinal fluid leak or postoperative sequelae. This analysis indicates that split-thickness calvarial grafts can be safely and adequately performed in children as young as 13 months of age.

Bone Transplantation↗

PubMed1997

Analysis of bone formation after cranial osteotomies with a high-speed drill.

Ten New Zealand white 22-week-old rabbits were divided into two groups of five each. The Midas Rex drill with a C-1 drill bit was used to make a full-thickness sagittal osteotomy 2 cm in length. A B-5 bit and footplate attachment were used to make a 2-cm linear osteotomy parallel to the first. Four drill holes 1 mm in diameter were made over the nasal bones on the ipsilateral side. In Group A animals, half of the skull had no irrigation; the other half of the skull was irrigated with room temperature saline. In Group B animals half of the skull was irrigated with iced saline irrigation; the other half of the skull was irrigated with room temperature irrigation fluid, and the osteotomy sites were filled with bone wax. Specimens were harvested at 8 weeks and evaluated grossly and histologically. The results showed that all the drill holes closed in the nasal bones regardless of the type of irrigation used or whether bone wax was used. Iced saline irrigation and room temperature irrigation had similar positive effects on bone formation in contrast to the no-irrigation group, which had inferior bone formation. Bone wax appeared also to have a detrimental effect on bone formation.

Animals↗

PubMed1997

Posttraumatic anosmia in craniofacial trauma.

Although the clinical implications of anosmia can be significant, posttraumatic anosmia is generally given relatively little attention in the clinical setting. Patients who sustain craniofacial trauma are most at risk. The incidence of posttraumatic anosmia varies according to the severity of injury and has an overall estimated incidence of 7%. Factors that increase the risk of developing anosmia include anterior skull base fractures, bilateral subfrontal lobe injury, dural lacerations, and cerebrospinal fluid leakage. Recovery of function has been estimated to be approximately 10%. Time of recovery, if it occurs, varies between 8 weeks and 2 years. Presented herein are the clinical, radiographic, pathophysiologic, and anatomic substrata of posttraumatic anosmia.

Adolescent↗

PubMed1996

Special considerations in pediatric cranial fixation: a technical overview.

Advances in plate fixation design have made possible traumatic and elective cranial reconstruction in pediatric patients. Plating systems must be selected properly, particularly in growing infants and children, in whom long-term computerized axial tomography (CAT) scanning and magnetic resonance imaging (MRI) may be necessary. Specific concerns include an actively growing skull with resulting dynamic bony contour changes. The results of 41 children with approximately 5 plates per case, totaling 205 implantable devices, were studied. This article addresses safety and image quality of metallic implants on CAT scan and MRI scanning, growth restriction induced by rigid plating systems, passive internal displacement of plates and screws with possible dural and cortical penetration, plate and screw isolation, and recommendations for cranial fixation in children.

Animals↗

PubMed1995

The Sunrise Technique: the correction of occipital plagiocephaly using bandeau occipital plate and radial osteotomies.

Posterior plagiocephaly secondary to lambdoid suture stenosis requires surgical release and repair to prevent progressive deformational changes associated with a suture stenosis. A surgical technique is described for release of the stenosed lambdoid suture and asterion region, followed by occipital reconstruction. This technique provides excellent cosmetic results. Using a standard biparietal incision, most of the occipital bone is removed en bloc. The asymmetric occiput is then reconstructed using an autologous bone bandeau and Marchac forehead template graft. The remaining bone is cut into longitudinal strips and placed in a centrifugal fashion around this construct. This technique creates a stable unit that provides immediate symmetry to the occipital area. The operative time and blood loss are comparable to that of similar procedures. With this technique there have been no complications or need for reoperation.

Cranial Sutures↗

PubMed1995

Epidemiology of cerebrospinal fluid shunting.

The epidemiology of cerebrospinal fluid (CSF) shunting in the United States is not well known; however, with recent national surveys, the prevalence, incidence, and cost of these procedures can be estimated. The prevalence of CSF shunts in the United States appears to be greater than 125,000, though this is likely an underestimate of the true value. There are approximately 69,000 discharges each year with the diagnosis of hydrocephalus. These visits produce nearly 36,000 shunt-related procedures, 33,000 of which involve the placement of a shunt. CSF shunting procedures account for almost US$ 100 million of national health care expenditures each year. Unfortunately, nearly half of these dollars are spent on revision. The rates and costs of CSF shunting underscore the need for continued improvement in both materials and techniques.

Adolescent↗

PubMed1995

Intraoperative autologous blood transfusion in the surgical correction of craniosynostosis.

Transfusion of homologous blood is associated with significant and well-known risks. Reported transfusion rates for pediatric patients undergoing surgical correction of synostotic calvarial sutures vary between 20 and 500% of estimated blood volume. The objective of this study was to ascertain the risks, benefits, and effects on transfusion rates associated with the use of intraoperative autologous transfusion (IAT) in this patient population. The Haemonetics Cell Saver 4 (Haemonetics Corporation, Braintree, MA) autotransfusion system was used to salvage blood in 18 patients undergoing the release of stenosed calvarial sutures. In a prospective, nonrandomized study, these patients were compared with a control group of similar age, gender, weight, and surgical procedures. There were 10 male patients and 8 female patients; the mean age was 7.2 months, the mean weight was 8.67 kg, and the mean surgical time was 3.15 hours. The mean amount of homologous blood transfused to the control group was 189 ml, compared with 87.69 ml for the IAT group, which was a decrease of 46.3%. The mean amount of autologous blood transfused was 150 ml (range, 50-250 ml). Thirty-three percent of the patients in the IAT group did not require homologous blood transfusion. No complications were observed with the use of the Cell Saver in the IAT group. The use of the Cell Saver was associated with a significant decrease in the amount and rate of homologous blood transfusions. Its use appears to be safe in pediatric patients undergoing craniosynostotic surgery.

Blood Loss, Surgical↗

PubMed1995

Carotid-cavernous sinus fistulae in craniofacial trauma: classification and treatment.

Carotid-cavernous sinus fistulae (CCF) represent pathological communications between the intracavernous internal carotid artery and the cavernous venous sinus. Although trauma is the most common cause of high flow carotid cavernous fistulae, they are relatively uncommon in patients sustaining craniofacial trauma. Nevertheless, CCF require early diagnosis and rapid and effective treatment in order to prevent severe and significant morbidity. Clinical presentation may include pulsatile proptosis, ocular and orbital erythema, chemosis, diplopia, headaches, and visual loss. Cerebral angiography is currently the definitive diagnostic study. Obliteration of the fistula by endovascular techniques is the current mainstay treatment, and direct surgery is reserved for cases that have failed endovascular therapy. This article reviews clinical features, pertinent anatomy, and therapeutic approaches to carotid-cavernous sinus fistulae.

Arteriovenous Fistula↗

PubMed1995

Stereotactic surgery in the management of intracranial disorders.

Fifty-six stereotactic procedures (thirty-eight stereotactic biopsies, 13 stereotactic craniotomies, and 5 implantations of intracranial catheters) were performed on 54 patients at the University of Missouri between 1990 and 1994. In 89.5% of cases a definitive diagnosis was made by stereotactic biopsy with a major complication rate of 2.6%, rates comparable to other published series. Stereotactic craniotomy was associated with no mortality and minimal morbidity. Stereotactic surgery is a safe and effective technique that improves the management of many intracranial disorders.

Adolescent↗

PubMed1994

Silicone allergy in ventriculoperitoneal shunts.

Reported are the cases of three hydrocephalic patients who developed a clinically heterogenous entity with an allergic rejection of their silicone ventriculoperitoneal shunts. All of the patients had an original presentation indicative of a shunt infection, but laboratory analysis revealed sterile cerebrospinal fluid in all three cases. The typical course included recurrent skin breakdowns over the shunt tract, subsequent infections and development of fungating granulomas. Treatment, with successful resolution of the symptoms, included changing the shunt material from silicone to polyurethane, with immunosuppression in one patient and removal of the shunt altogether in the other two patients. The roles of the immune system and silicone in the pathophysiology of this condition are discussed.

Adolescent↗

PubMed1994

Achondroplasia: pre- and postsurgical considerations for midface advancement.

Achondroplasia, the most common type of dwarfism, involves several physical characteristics that can cause pre- and intraoperative respiratory problems. The characteristics include rib-cage deformities, midface hypoplasia, choanal stenosis, muscular hypotonia, foramen magnum compression, and cervical abnormalities. Specific pre- and postoperative strategies for dealing with achondroplastic dwarfs are discussed.

Achondroplasia↗

PubMed1994

Asterion region synostosis.

Posterior plagiocephaly historically has been associated with synostosis of the lambdoid suture. The incidence, diagnosis, and modes of treatment for stenosis of the lambdoid suture remain controversial. Commonly, the lambdoid suture is found to be open both on radiographic examination and at the time of surgery. The study reports on nine patients who presented with unilateral posterior plagiocephaly and who were found to have open lambdoid sutures, but a stenosed region of the asterion. The area of involvement included the distal-most lambdoid suture, the parietomastoid, occipitomastoid, and proximal squamosal sutures. Positional molding or torticollis was ruled out in all patients. All the patients showed progressive involvement of the skull base, including anterior shifts of the ipsilateral ear, compensatory ipsilateral frontal bossing and malar protrusion. Stenosis of the asterion was diagnosed with three-dimensional computed tomography scans, corroborated at the time of surgery and confirmed histologically. Surgical correction involved resection of the affected asterion and reconstruction using a bandeau-technique, barrel staves of the occipital bone and bone graft transposition. This approach provided excellent esthetic results in all patients.

Cranial Sutures↗

PubMed1994

Calvarial defect reconstruction.

The history of skull trepanation is almost as old as that of humanity. For thousands of years it has been performed for the treatment of numerous medical maladies. The Andean Incas, early Asians and South Seas Islanders, are amongst the many people to perform calvarial trepanation. Hippocrates described techniques for the use of the trepan in early Greek times. With the production of a skull opening comes the challenge of developing methods for closing the defect. It is in reality, more challenging to repair the defect than to create it. Man, with his never ending ingenuity, has tried to develop many techniques. We will discuss some of them and present our method of choice for closure of skull defects.

Bone Transplantation↗

PubMed1993

Distraction of the frontal bone outside the cranial plane: a rabbit model.

Distraction of the frontal bone outside the cranial plane using the Ilizarov principle was performed in 17 22-week-old New Zealand white rabbits. Five rabbits had frontal bone osteotomy only and were in the control group; 5 rabbits were placed in the sham control group and had frontal bone osteotomy plus application of a customized headgear appliance; and 7 rabbits were placed in the experimental group, which underwent frontal bone osteotomy application of the headgear and distraction. The frontal bone was elevated 1 mm every other day for a period of 8 weeks, and the animals were then killed. Cephalometry was performed both preoperatively and at the end of the 8-week period. Histological examination of the skulls was also performed. The experimental group showed a significantly elevated frontal bone compared to the sham control group (p < 0.05). Callous bone filled the distracted segment, which united the frontal bone with the cranial plane. Therefore, frontal bone advancement by distraction osteogenesis is possible using this rabbit model.

Animals↗

PubMed1992

Blood-flow measurements of injured peripheral nerves by laser Doppler flowmetry.

The effects of injury on peripheral nerve blood flow were studied, using a Laserflo blood perfusion monitor. A total of 11 nerves were studied, five normal and six injured nerves in four patients. Two of the patients had lacerating brachial plexus injuries, and two other patients had compressive neuropathies of their ulnar nerves at the elbow. All of the readings were taken intraoperatively while the patients were undergoing exploration and repair under general anesthesia. Measurements of the damaged nerves were taken serially from the site of injury proximally and distally, by approximating a flexible metric ruler to the dorsal aspect of the nerve along the same axis. In the acutely lacerated injured nerves (3 to 7 days), the measurements were taken at 1, 5, 10, and 20 mm. The maximal amount of retraction in any of the nerves was 1 cm; thus, the overall architecture of the nerves was maintained. In the compressed nerves, measurements were taken at 1, 2 and 3 cm proximal and distal to the medial epicondyle. Measurement of normal undamaged nerves was performed at six different sites along the same axis of the nerve. The averaged results indicate that the normal blood flow ranged from 47 ml/100 g/min to 63 ml/100 g/min, with a mean of 56 ml/100 g/min. In the injured nerves, blood flow was most depressed at sites closest to the laceration, and increased consistently and progressively at sites distant from the injury in both directions.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗