Use of acetazolamide to decrease cerebrospinal fluid production in chronically ventilated patients with ventriculopleural shunts

Acetazolamide (ACTZ), a carbonic anhydrase inhibitor, has been shown to decrease cerebrospinal fluid (CSF) production in both in vivo and in vitro animal models. We report two children with hydrocephalus who experienced multiple shunt failures, and who had externalised ventriculostomy drains (EVD) prior to ventriculopleural shunt placement. The effects of increasing doses of ACTZ on CSF production and subsequent tolerance to ventriculopleural shunts were evaluated. The patients had a 48% and a 39% decrease in their EVD CSF output when compared to baseline with maximum ACTZ dose of 75 mg/kg/day and 50 mg/kg/day, respectively (p < 0.05). This is the first report of change in CSF volume in children after extended treatment with ACTZ. ACTZ treatment in mechanically ventilated paediatric patients with hydrocephalus may improve tolerance of ventriculopleural shunts and minimise respiratory compromise. Potassium and bicarbonate supplements are required to correct metabolic disturbances.     

Management of hydrocephalus in infancy: use of acetazolamide and furosemide to avoid cerebrospinal fluid shunts

Despite its effectiveness, cerebrospinal shunting for hydrocephalus continues to be accompanied by considerable complications and morbidity. Medical therapy with acetazolamide 100 mg/kg/day and furosemide 1 mg/kg/day can be an effective alternative to shunting by halting progression of hydrocephalus until such time as sutures can become fibrosed and spontaneous arrest can occur. In an appropriately selected population older than 2 weeks with hydrocephalus of varied origin, our success rate in avoiding shunting is greater than 50%. The dramatic difference between the number of hospitalizations of patients with shunts and those treated medically, and the potential to avoid shunt dependence would appear to make an initial trial with medical therapy worthwhile.     

Management of pregnant women with cerebrospinal fluid shunts.

As more women with cerebrospinal fluid shunts reach child-bearing age, neurosurgeons, obstetricians and other health care providers will increasingly be called upon to care for them once they become pregnant. A review of the literature reveals that these patients may develop symptoms of shunt malfunction as uterine size increases. In most cases, symptoms can be managed conservatively during pregnancy and usually resolve following delivery. The presence of a CSF shunt per se, is not a contraindication to pregnancy and eventual fetal and maternal outcome has been excellent in the majority of cases. Labor and delivery should be allowed to progress naturally and interventions limited to those indicated for obstetrical reasons alone. Peripartum prophylactic antibiotics may be indicated and special care ought to be exercised if epidural analgesia or cesarian section is deemed necessary. Genetic investigations and counseling may be indicated in selected patients.     

Infections in cerebrospinal fluid shunts

Bacterial colonization of cerebrospinal fluid shunts is a cause of significant morbidity, causing not only shunt malfunction and chronic ill-health but has also been implicated in an immune-complex glomerulonephritis. Almost all shunt colonizations involve Staphylococcus albus which gains access to the shunt during surgery and grows in microcolonies inside the shunt. The most reliable means of diagnosis at present is serological surveillance. Medical management is usually ineffective in eradicating colonization and colonized shunts must be replaced. Recent work on the impregnation of Silastic with antimicrobial substances to prevent colonization has provided encouraging results.     

Complications of cerebrospinal fluid shunts

In the period 1972–81, 572 hydrocephalic children were treated using the Upadhyaya shunt valve, One hundred and seventys-even of these patients needed a total of 350 shunt revisions. Indications for revisions were; shunt blockage 245 (70% of total revisions) shunt infections 40 (11.5%) catheter disconnections/fractures 19 (5.5%) and intvacranial hemorrhage 9 (2.5%). Intracranial bleeds were more commonly seen in hydrocephalus associated with tuberculous meningitis and were invariably fatal. Infrequent complications were CSF leak, shunt extrusion, valve incompetence, pulmonary hypertension and pleural effusion. Thirty-nine patients died. Overall results of the Upadhyayay shunt valve compare favourably with other reported series.     

Bacillus species isolates from cerebrospinal fluid in patients without shunts

Of 849 CSF cultures done at Hartford Hospital, nine were positive for nonanthrax Bacillus species. Differentiation of true nonanthrax Bacillus species infection from contamination requires careful consideration of the clinical findings, the clinical course, and the laboratory data. In seven patients the nonanthrax Bacillus species represented contamination. In two patients the nonanthrax Bacillus species represented true infection. In one of these infected patients, nonanthrax Bacillus species complicated a cranial gun shot wound. Bacillus cereus meningitis developed in the second patient, a premature infant, following sepsis from a contaminated IV catheter. Nonanthrax Bacillus species, especially B cereus, can be resistant to penicillins and cephalosporins when nonanthrax Bacillus species infections are being treated, susceptibility testing should always be performed.     

Common complications of cerebrospinal fluid shunts

When any child who has a CSF shunt in situ becomes unwell, the diagnosis of shunt blockage should be considered. If no other cause for his illness can be found then shunt blockage must be excluded and the problem discussed at the earliest possible opportunity with the staff of the local neurosurgical centre before emergency measures to reduce the intracranial pressure become necessary.     

Abdominal ultrasound in the diagnosis of cerebrospinal fluid pseudocysts complicating ventriculoperitoneal shunts.

Pseudocysts filled with cerebrospinal fluid caused complications at the distal end of ventriculoperitoneal shunts in five children. Only one of these cysts was infected. The children presented with raised intracranial pressure or abdominal symptoms, or both. We report on the usefulness of abdominal ultrasound examination in the diagnosis and follow up of these patients and suggest that abdominal ultrasound should form part of the initial assessment of children with ventriculoperitoneal shunt dysfunction.     

Physical examination of patients with cerebrospinal fluid shunts: is there useful information in pumping the shunt?

To assess the value of the information derived from pumping the shunt valve in hydrocephalic patients with cerebrospinal fluid shunts, the findings on examination of 200 consecutive patients were recorded prospectively. The status of each shunt was determined on the basis of all available clinical data, and the results of the shunt pumping test were compared to the final status of each shunt for various subsets of the study group. In the most clinically pertinent subsets, the sensitivity of the shunt pumping test in the detection of shunt obstruction was 18% to 20%, and the predictive value of a negative shunt pumping test, indicating shunt patency, was only 65% to 81%. For the hydrocephalic patient with symptoms of shunt malfunction, definitive imaging studies must not be deferred because of reassuring findings on examination of the shunt valve.     

Serum C-reactive protein test in diagnosis of septic complications of cerebrospinal fluid shunts for hydrocephalus.

Serial tests for serum C-reactive protein (CRP) were carried out on 40 children undergoing cerebrospinal fluid shunt surgery, to determine the pattern of appearance and disappearance of CRP in relation to this type of operation, in the absence of postoperative complications. Samples of sera from a further 268 children, 79 of whom presented after shunt surgery with symptoms suggesting infective complications related to the shunt, were examined for CRP. The results showed that, while the test in negative in uncomplicated colonisation of ventriculo-atrial shunts, it is reliably positive in patients with colonised ventriculo-peritoneal shunts, ventriculitis, or shunt nephritis.     

Ferritin in cerebrospinal fluid of patients with lymphoproliferative disorders

The ferritin concentration in cerebrospinal fluid (CSF) from children and three adults with lymphoproliferative disorders was determined. While these levels were normal in children without CNS involvement before treatment, they rose during induction therapy and remained high also during consolidation therapy. As the intensity of treatment decreased during the consolidation phase, CSF ferritin declined but did not reach pretreatment concentrations. After three years of maintenance therapy (without intrathecal injections) CSF ferritin was normal. CSF ferritin concentration does not reflect the stage of the disease but seems to correlate to the treatment, especially if this is administered intrathecally. In adults with CNS involvement, CSF ferritin showed no correlation to the CSF cell count, the degree of CNS involvement or to the treatment. It is of little use in demonstrating the spread of the malignant process to the CNS.     

Plasma and cerebrospinal fluid arginine vasopressin in patients with and without fever.

Hyponatraemia has been described in association with a number of acute infectious diseases, mainly bacterial and tuberculous meningitis and pneumonia, and has been attributed to inappropriate secretion of arginine vasopressin (AVP). The mechanism of inappropriate AVP production is uncertain, but there is experimental evidence to suggest that fever may stimulate secretion of AVP into plasma and cerebrospinal fluid. In this study, AVP concentrations in plasma and cerebrospinal fluid from 37 febrile children with infections have been compared with those from 27 afebrile control subjects. Ten of the febrile children had meningitis (eight bacterial, two viral) and the remainder a variety of other infectious diseases. Seventy four per cent of febrile infected children were hyponatraemic (serum sodium less than 135 mmol/l) compared with only 8% of the afebrile controls. Plasma AVP concentrations were significantly higher in the febrile patients (median 2.92 pmol/l, range 1.0-23.25, n = 28) than in controls (median 1.67 pmol/l, range 0.57-6.0, n = 14) but there was no significant difference in cerebrospinal fluid AVP concentrations. There was no difference in plasma AVP concentrations between patients with meningitis and those with infections not involving the central nervous system. Careful attention should be paid to fluid and electrolyte balance in all children with acute infections.     

Measurement of cerebrospinal fluid output through external ventricular drainage in one hundred infants and children: correlation with cerebrospinal fluid production

OBJECTIVE: Cerebrospinal fluid (CSF) production rates influence shunt design and the care of children with hydrocephalus. Measurement of hourly CSF output through external ventricular drainage (EVD) reflects the CSF production. In the present study, hourly CSF outputs in children with hydrocephalus were measured while they were treated with EVD and correlated with the age, sex and body weight of the patients as well as other clinical parameters. METHODS: One hundred children with hydrocephalus due to various causes had EVD treatment. Twenty-six had EVD on two or three separate occasions; thus, the CSF output measurements were observed and analyzed on the basis of 130 EVDs. The most common reason for EVD treatment was shunt infection (n = 75). The duration of EVDs ranged from 25 to 774 h (mean 269 h). The height of the drip chamber from the mid-head position ranged from 0 to 23 cm (mean 9.8 cm). The hourly CSF output was analyzed according to the patient's age, sex and body weight as well as the presence of CSF infection. RESULTS: The hourly CSF output rapidly increases during the first year of life. By the second year, it reaches 64% of the hourly CSF output of 15-year-old children. The mean hourly output ranged from 0.1 to 26.5 ml/h (mean 8.1 ml/h), with the standard deviation ranging from 0.4 to 10.8 ml/h (mean 5.2 ml/h). A regression analysis indicated that the age and body weight appeared to correlate with the hourly CSF output. Using the natural logarithm of age, body weight and sex, these predictors accounted for 50.9% of the variability in hourly CSF output. The regression equation is as follows: hourly CSF output = 2.78 - 2.23(male = 0, female = 1) + 0.97 log(age in years) + 2.26 log(body weight in kg). R sd = 3.36, R(2) = 0.509. The type of infecting organism and the height of EVD did not influence the overall CSF output. CONCLUSION: The hourly CSF output fluctuates, but the CSF output increases logarithmically with age and body weight. The gender also influences the CSF output, with males having a greater output than females. The data produced by the present study will help us to understand CSF production rates in developing children. They will also help us in the care of children receiving EVD treatment, as well as in selecting and designing shunt systems.     

Estimation of mortality risk in chronically ventilated infants with bronchopulmonary dysplasia

Bronchopulmonary dysplasia is a chronic, sometimes fatal lung disease, which primarily affects premature infants and often leads to a dependence on mechanical ventilation lasting many months. To identify prognostic factors of mortality at 1 and 2 months of age, the authors reviewed the medical records of the 144 neonates admitted to two neonatal intensive care units in Seattle from January 1, 1986, through December 31, 1988, who required mechanical ventilation throughout the first month of life. Likely predictors of mortality were tested by logistic regression analysis. The calculated mean airway pressure at 30 days of age (MAP30) and the diagnosis of bacterial sepsis at any time during the first month of life (Bact 0-30) were statistically significant predictors of mortality (P less than .001 and P = .018, respectively) and had the lowest deviance in the regression model. The probability of mortality was estimated by 1/(1 + e-chi), where chi = -6.510 + 0.4588 (MAP30) + 1.475 (Bact 0-30), and where MAP30 is expressed as centimeters of water pressure (1 cm H2O = 0.0978 kPa) and the presence or absence of bacteremia is 1 and 0, respectively. The records of the 57 infants who still required mechanical ventilation at 60 days of age were reanalyzed with clinical data available during the first 2 months of life. Mean airway pressure (MAP 60) and the fraction of inspired oxygen (F60) at 60 days of age combined to form the best predictors of mortality, where chi = 7.668 + 0.2940 (MAP 60) + 5.935 (F60).(ABSTRACT TRUNCATED AT 250 WORDS)     

Permissive hypercapnia to decrease lung injury in ventilated preterm neonates

Lung injury in ventilated premature infants occurs primarily through the mechanism of volutrauma, often due to the combination of high tidal volumes in association with a high end-inspiratory volume and occasionally end-expiratory alveolar collapse. Tolerating a higher level of arterial partial pressure of carbon dioxide (PaCO2) is considered as 'permissive hypercapnia' and when combined with the use of low tidal volumes may reduce volutrauma and lead to improved pulmonary outcomes. Permissive hypercapnia may also protect against hypocapnia-induced brain hypoperfusion and subsequent periventricular leukomalacia. However, extreme hypercapnia may be associated with an increased risk of intracranial hemorrhage. It may therefore be important to avoid large fluctuations in PaCO2 values. Recent randomized clinical trials in preterm infants have demonstrated that mild permissive hypercapnia is safe, but clinical benefits are modest. The optimal PaCO2 goal in clinical practice has not been determined, and the available evidence does not currently support a general recommendation for permissive hypercapnia in preterm infants.