Experience with use of extended length peritoneal shunt catheters

The placement of a ventriculoperitoneal (VP) shunt is the current treatment of choice for diversion of cerebrospinal fluid associated with hydrocephalus. Although there are a host of reported potential abdominal complications related to the procedure, they are notably uncommon. The authors report their experience with the primary insertion of an extended length open-ended peritoneal tubing (120 cm) undertaken expressly to avoid the need for a lengthening procedure because of growth of the patient. In a review of new insertions of VP shunts using the extended length tubing over a 14-year period at Childrens Hospital of Los Angeles, a total 998 shunts were placed in 952 patients, with a mean follow-up period of 6.7 years. The patients experienced a total of 52 distal shunt revisions for a variety of malfunction etiologies. In patients ranging in age from premature neonate to 20 years, there was no increase in the distal complication rate, and specifically no complications were experienced that were directly related to the use of the extended length tubing. The authors conclude that the use of an extended length peritoneal shunt catheter is not associated with an increase in complications and eliminates the need to lengthen the peritoneal catheter for growth of the patient.     

The significance of blood pressure measurements in patients with peripheral vascular disease

The pressure drop across a stenosis is related only to its geometry and the flow through it. Flow may be manipulated by changing peripheral resistance, enabling information to be gained about the severity of the stenosis. As changes in blood flow may produce changes in local blood pressure in patients with peripheral arterial disease, measurements of blood pressure should be made at flow conditions appropriate to the symptoms under investigation, or should be performed by methods which do not intrinsically alter flow.     

Age-related differences in simultaneous interarm blood pressure measurements

Simultaneous noninvasive blood pressure measurement were recorded bilaterally in 40 young and 40 elderly subjects. Overall interarm blood pressure (BP) differences for the elderly and young groups were similar, the absolute interarm differences being for systolic blood pressure (SBP) elderly: 4.2 mmHg (95% CI 3.1-5.3 mmHg); young 3.3 mmHg(2.6-4.1 mmHg); diastolic blood pressure (DBP) elderly 3.6 mmHg(2.8-4.4 mmHg), young 2.7 mmHg(2.0-3.3 mmHg). However, the range of interarm BP differences was wide. Four (10%) of the elderly had an interarm SBP difference > 10 mmHg compared to one (3%) of the young group. Interarm DBP differences > 8 mmHg were found in three (8%) of the elderly and in none of the young group. Although age does not affect mean interarm BP differences, clinically important interarm BP differences exist in both young and elderly subjects. Blood pressure should be measured in both arms of all patients at initial assessment to avoid potential problems with misclassification of blood pressure status.     

Subbandage pressure measurements comparing a long-stretch with a short-stretch compression bandage

Although angioplasty has undergone considerable development, restenosis remains an unsolved problem. No drugs have been proved effective in the prevention of restenosis. Prophylactic stenting is the only treatment with some efficacy. The pathophysiology of restenosis involves both intimal hyperplasia with a major proliferative component at the dilated site and geometric constrictive remodeling of the artery. Stenting seems to prevent the remodeling but does not prevent and may even worsen the intimal hyperplasia. Gene therapy may be effective in preventing the proliferative component of the intimal hyperplasia: therapeutic genes can be delivered locally to the arterial wall cells at the dilated site during or immediately after angioplasty, using viral (e.g., adenoviruses) or nonviral vectors. The main candidate genes stimulate a variety of endogenous mechanisms whose effects consist in inhibition of smooth muscle cell proliferation (Rb gene); sensitization of proliferating cells to the effects of cytotoxic substances, thus allowing selective chemotherapy (HSV-tk gene); or stimulation of reendothelization (VEGF gene). Other genes have also yielded promising results (ecNOs, p21, Coxl, etc.). Clinical application of these techniques cannot be envisioned until studies are available proving that the delivery methods (transfer vectors or local delivery systems) are completely safe, and that the candidate genes are effective in "realistic" models. If these hurdles are cleared successfully, preventive gene therapy for gene restenosis may well become a clinical reality.     

The successful use of continuous negative extrathoracic pressure in a child with Glenn shunt and respiratory failure

Following a Glenn shunt, an infant required mechanical ventilation (IPPV) for pneumonia, a phrenic nerve palsy and chylothoraces. In order to improve her deteriorating clinical condition, we used continuous negative extrathoracic pressure (CNEP) to minimise the deleterious effects of IPPV on pulmonary blood flow. She was successfully weaned from IPPV and supported with CNEP.     

Silicone elastomer cerebrospinal fluid shunt systems. Council on Scientific Affairs, American Medical Association

A 1995 resolution of the American Medical Association House of Delegates, introduced by the American Academy of Neurology, the American Association of Neurological Surgeons, and the Congress of Neurological Surgeons, asked the American Medical Association Council on Scientific Affairs to add the use of hardened silicone shunts to its study of the effects of silicone gel used in breast implants. On consideration of the important differences between the two materials, silicone elastomer ("hardened silicone") and silicone gel, the Council on Scientific Affairs elected to address the subject of silicone elastomer shunt systems separately. This report describes the different types of medical-grade silicone used in medical devices, the incidence of hydrocephalus and its causes and treatment, and the use of cerebrospinal fluid shunt systems made of silicone elastomer. Published case reports of possible immunological disease in patients who have had silicone elastomer cerebrospinal fluid shunt systems implanted are reviewed. The Council on Scientific Affairs concluded that the evidence presented does not support the occurrence of immune-mediated systemic reactions to implanted silicone elastomer cerebrospinal fluid shunt systems. The local granulomatous or inflammatory responses observed in some patients with silicone shunt systems have not been shown to be immunologically mediated; similar reactions have been described with other implanted foreign bodies.     

Avoiding complicated shunt systems by open fenestration of symptomatic fourth ventricular cysts associated with hydrocephalus

BACKGROUND: The effect of thyroid orbitopathy on intraocular pressure (IOP) remains controversial. We carried out a study to determine the effect of orbital decompression surgery on the IOP in patients with advanced thyroid orbitopathy. METHODS: The records of 12 consecutive patients (22 eyes) who underwent decompression surgery for severe thyroid orbitopathy between 1985 and 1996 were reviewed. All patients were maintained on essentially the same medications before and after surgery. The IOP readings, obtained by means of applanation tonometry in primary gaze, from the pre- and postoperative visits were recorded, and the net change was calculated. RESULTS: The mean preoperative and postoperative IOP values were 19.8 mm Hg and 16.8 mm Hg respectively, a significant difference (p = 0.008). Seven of eight eyes with an IOP of 21 mm Hg or greater preoperatively had a postoperative IOP less than 21 mm Hg; these eyes showed a mean decrease in IOP of 5.6 mm Hg. The degree of preoperative IOP elevation was found to be a strong predictor of the amount of IOP lowering after surgery (p = 0.014). INTERPRETATION: Our results support the concept that orbital congestion associated with thyroid orbitopathy produces an increase in IOP by elevation of episcleral venous pressure (EVP) and that orbital decompression may reduce the IOP by decreasing EVP. Decompression surgery may obviate the need for more aggressive management of glaucoma in patients with severe thyroid orbitopathy.     

Pharyngeal pressure measurements in topodiagnosis of obstructive sleep apnea]

In order to improve the outcome of surgical treatment for obstructive sleep apnea syndrome certain reports have claimed to identify the site of obstruction in the upper airway. One of the various methods available for topodiagnosis is manometry using intraesophageal and intrapharyngeal pressure probes. In the present literature the surgical success rate for patients undergoing Uvulopalatoplasty (UPP) as treatment for retropalatal obstructions is approximately 50%. For patients with other sites of obstruction the success rate is below 10%. The aim of this study was to evaluate the different theories explaining the still low outcome of UPPP in patients with only retropalatal collapse. Findings showed that measurements within different sleep stages and at different pharyngeal activities during sleep can lead to different results concerning sites of obstruction. Additionally, any surgery to one part of the pharynx seems to influence the other parts of the pharynx in caudal and cranial directions. A literature theory dominates that the pharynx between the nasopharynx and lower hypopharynx acts like several Starling mechanism in series, in which are influences the other. Whether more complicated pressure measurements emphasizing the role of sleep stages and pharyngeal muscle activities could improve the surgical outcome of UPPP is the subject of present investigations. In any case the technical equipment and time consumption of the measurements required will probably disqualify the method for routine use.     

Noninvasive measurements of digital arterial pressure and compliance in man

A noninvasive method was developed for measuring the digital arterial pressure and the compliance by using a fingertip pneumoplethysmograph and a pneumatic cuff. The compliance (C) of the digital artery was obtained from the peak amplitude of the volume pulse wave (deltaVp-a) under the effect of the cuff pressure (Po-a) by the equation: C = deltavp-a/(Ps - P-o-a) during the dicrotic phase defined in this study. The normal mean value was 11.37 +/- 0.59 X 10(-5) cm3/mmHg. On lowering of the cuff pressure, the moment when the deltaVp value becomes positive is regarded as the systolic pressure (Ps). At the end of the dicrotic phase, the mean amplitude (deltaVss') of the pulse wave during one pulse cycle (SS') and the ratios (deltaVss'/deltaVsd), where deltaVsd is the mean amplitude of the wave during the systolic period (SD), of successive waves after a particular wave fail to increase at the same rate when the cuff pressure decreased below the diastolic pressure. The cuff pressure corresponding to this particular wave is regarded as the diastolic pressure (Pd). The mean value of the mean digital pressure of normotensive subjects was 80.6 +/- 1.2 mmHg.     

Hysteresis in force probe measurements: a dynamical systems perspective

BACKGROUND: This study was designed to investigate the effects of a modified University of Wisconsin (UW) solution supplemented with one of four buffering agents (histidine, bicine [N,N-bis(2-hydroxyethyl)glycine], tricine [N-tris(hydroxymethyl)methylglycine], and Tris) on liver metabolism during cold ischemic storage. METHODS: Rat livers were flushed and stored for a maximum period of 24 hr at 4 degrees C, and tissue energetics, substrate, and anaerobic end-products were assessed; the group exhibiting the best results during storage was recovered in a 60-min period of warm reperfusion. Relative buffering capacities of the experimental solutions (measured over physiological pH range, in mM H+/L) were: UW, 4.1; histidine+UW, 9.8; Tris+UW, 19.0; bicine+UW, 22.5; tricine+UW, 26.8. RESULTS: In the UW group, ATP levels dropped rapidly over the first 4 hr; 1.0 micromol/g (40% of initial) remained after 4 hr of storage. By 2 hr, ATP levels in bicine- and tricine-treated groups were 0.5 and 1.1 micromol/g greater than in the UW-stored livers and by 10 hr, ATP in bicine-treated livers was twofold that of the control (UW) group. Total adenylate levels also reflected a superior elevation of cellular energetics; even after 24 hr, quantities were 1.4 and 2.0 micromol/g higher than the UW group in bicine- and histidine-supplemented organs. The increase in energetics occurred as a result of increased flux through the major anaerobic energy-producing pathway, glycolysis. The glycolytic rate was significantly greater at storage times > 10 hr with solutions supplemented with bicine, histidine, and tricine. Final values for net lactate accumulation over the entire 24-hr storage period were: UW, 10.1 micromol/g; histidine, 14.3 micromol/g; bicine, 15.2 micromol/g; tricine, 13.8 micromol/g. Activities of glycogen phosphorylase revealed that the activity of this enzyme dropped by 50% within 2 hr of storage in UW. However, histidine and bicine supplementation resulted in a substantial elevation of phosphorylase "a" over 4 hr and 10 hr, respectively. The best buffer of the four examined in this study was bicine; energetics, glycolytic flux, and patterns of adenylate regeneration upon reperfusion were markedly superior to modified UW solution. CONCLUSION: The results of this study suggest that supplementing the "gold standard" UW solution with an additional buffering agent (in order of efficacy: bicine>tricine>histidine) may improve the metabolic status of livers during clinical organ retrieval/storage.     

Non-invasive blood pressure measurements in cats: clinical significance of hypertension associated with chronic renal failure

Gynaecological examination of girls during childhood is undertaken somewhat infrequently. These genital examinations should not be taboo or a frightening experience for the girl, for her parents or for the physician. Studies of children suspected of sexual abuse have paid attention to the wide variety of gynaecological conditions already present in childhood. In 1988 we founded a special gynaecological outpatient clinic for girls under 16 y of age at a university hospital to develop the special knowledge and skills needed in children's gynaecology. In this gynaecological clinic for children and adolescents we were able to gain and offer expert knowledge of the problems of this age group. In this special clinic for children, gynaecological examination by special techniques and sonography led to a diagnosis in 71% of the patients without any instrumentation. Children and adolescent girls in need of special gynaecological care should be recognized specifically. Particular attention should be paid to the gynaecological care of victims of child sexual abuse and mentally or physically handicapped girls. In good co-operation with the girl, a gynaecological examination can become a positive experience during the development of female identity.     

Interface pressure measurements of support surfaces with subjects in the supine and 45-degree Fowler positions

The results of treatment of 35 intraarticular distal fractures of the femur are presented. Treatment was performed in 8 cases with a condylar plate, in 8 cases with dynamic compression screw (DCS), in 2 cases with two plates, in 9 cases with screws only, and eight times the fracture was treated with a combination of lag screws and locking nail. Examination took place at an average of 45.5 months after the accident. 19 patients had an isolated fracture, 8 patients one accidental injury and 8 patients had more than one fracture or were polytraumatised. In 75% of the patients treatment lasted for between day 1 and 5. We found 17.1% open fractures and had to face infections in 5.7% (two cases). Bone healing occurred in all fractures, the reported infections could be overcome by early revision and the use of gentamycin-PMMA beds. It is remarkable that locking nails were successfully used in 8 cases of fractures with intraarticular component of the distal femur.     

Coronary collateral quantitation in patients with coronary artery disease using intravascular flow velocity or pressure measurements

OBJECTIVES: This study evaluated two methods for the quantitative measurement of collaterals using intracoronary (IC) blood flow velocity or pressure measurements. BACKGROUND: The extent of myocardial necrosis after coronary artery occlusion is substantially influenced by the collateral circulation. So far, qualitative methods have been available to assess the human coronary collateral circulation, thus restraining the conclusive investigation of, for example, therapies to promote collateral development. METHODS: Fifty-one patients with a coronary artery stenosis to be treated by percutaneous transluminal coronary angioplasty (PTCA) were investigated using IC PTCA guidewire-based Doppler and pressure sensors positioned distal to the stenosis. Simultaneous measurements of aortic pressure, IC velocity and pressure distal to the stenosis during and after PTCA provided the variables for calculating collateral flow indices (CFIv and CFIp) that express collateral flow as a fraction of flow via the patent vessel. Both CFIv and CFIp were compared with conventional methods for collateral assessment, among them ST-segment changes >1 mm on IC and surface electrocardiogram (ECG) at PTCA. Also, CFIv and CFIp were compared with each other. RESULTS: In 11 patients without ECG signs of ischemia during PTCA (sufficient collaterals), relative collateral flow amounted to 46% as determined by Doppler and pressure wire. Patients with insufficient collaterals (n=40) had relative collateral flow values of 18%. Using a threshold of CFI=30%, sufficient and insufficient collaterals could be diagnosed with 100% sensitivity and 93% specificity by IC Doppler, and 75% sensitivity and 92% specificity by IC pressure measurements. The agreement between Doppler and pressure measurements was good: CFIv=0.08 + 0.8 CFIp, r=0.80, p=0.0001. CONCLUSIONS: Intracoronary flow velocity or pressure measurements during routine PTCA represent an accurate and, at last, quantitative method for assessing the coronary collateral circulation in humans.     

Subjective measurements in television.

A discussion of the type of psychophysical experiments which are fruitfully carried out in studying the relation between physical circuit variables and the perception of television pictures by the viewer. (PsycINFO Database Record (c) 2010 APA, all rights reserved)