Susanna Ng

CSF Antibiotic Prophylaxis for Neurosurgical Patients with Ventriculostomy: a Randomised Study

The value of prophylactic antibiotics for patients with ventricular catheter for monitoring and CSF drainage is uncertain. 228 patients were randomised to receive perioperative antibiotics only (Unasyn, Group I) or prolonged antibiotics for the presence of the ventricular catheter (Unasyn and Aztreonam, Group II). The incidence of intracranial and extracranial infection was documented prospectively. Group II patients had a significantly reduced incidence of CSF infection [3/115 (3%) vs 12/113 (11%), p = 0.01] and extracranial infections [23/115 (20%) vs 48/113 (42%), p = 0.002]. CSF pathogens in Group II patients were MRSA and Candida, whereas in Group I, Staphylococci, E coli and Klebsiella. Although prolonged antibiotic prophylaxis significantly reduced the incidence of serious CSF infection as well as extracranial infections, this policy did select resistant or opportunistic pathogens such as Candida and MRSA.

Effect of early pulmonary rehabilitation on health care utilization and health status in patients hospitalized with acute exacerbations of COPD.

Background and objective:  Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) incur heavy utilization of health‐care resources for patients who require hospitalization. We evaluated whether an early outpatient pulmonary rehabilitation programme (PRP) after hospitalization for AECOPD could reduce acute health‐care utilization over the succeeding year.

Clipping vs coiling of posterior communicating artery aneurysms with third nerve palsy

The authors investigated the evolution of third nerve palsy in patients with posterior communicating artery aneurysms who underwent coiling vs clipping. There was no statistical difference of complete third nerve palsy recovery in both treatments. Both techniques were of clinical benefit. Older age, diabetes, delayed interventions, and complete third nerve palsy at presentation indicated a poor prognosis for recovery.

Effect of ischemic preconditioning on brain tissue gases and pH during temporary cerebral artery occlusion.

Previous studies have demonstrated that a brief period of ischemia protect against subsequent severe ischemic insults to the brain, i.e. preconditioning. We evaluated the effects of ischemic preconditioning, produced by 2 min proximal temporary artery occlusion, on brain tissue gases and acidity during clipping of cerebral aneurysm. Twelve patients with aneurysmal subarachnoid hemorrhage were recruited. All patients received standard anesthetics. After craniotomy, a calibrated multiparameter catheter was inserted to measure oxygen (PtO2) tension, carbon dioxide (PtCO2) tension and pH (pHt) in tissue at risk of ischemia during temporary artery occlusion. In patients assigned to the preconditioning group, proximal artery was occluded initially for 2 min and was allowed to reperfuse for 30 min. All patients underwent cerebral artery occlusion for clipping of aneurysm. The rate of change in PtO2, PtCO2 and pHt after artery occlusion were compared between groups using unpaired t test. Baseline brain tissue gases and pHt were similar between groups. Following artery occlusion, the decline in PtO2 and pHt were significantly slower in the preconditioning group compared with the routine care group. These results suggested that ischemic preconditioning attenuates tissue hypoxia during subsequent artery occlusion. Brief occlusion of the proximal artery may be a simple maneuver for brain protection during complex cerebrovascular surgery.

Measurement of tumor necrosis factor-α, leukotriene B4, and interleukin 8 in the exhaled breath condensate in patients with acute exacerbations of chronic obstructive pulmonary disease

Background Assessment of airway inflammation in the clinical course of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) may advance our understanding of the pathogenesis and treatment. Objectives To assess airway inflammation in patients during the course of AECOPD by serial analyses of their exhaled breath condensates (EBC). Methods Twenty-six patients with AECOPD (22 males, mean[SD] percentage predicted forced expiratory volume in one second (FEV1) 44.8 [14.3]), 11 with stable COPD, and 14 age and sex-matched healthy controls were studied. Patients with AECOPD were treated with systemic steroid and antibiotic for 7 days. EBC was collected from each patient with AECOPD on Day 5, 14, 30, and 60 post-hospitalization using EcoScreen (VIASYS Healthcare, USA) during tidal breathing over 10 minutes. Concentrations of tumor necrosis factor-α (TNF-α), leukotriene B4 (LTB4), and interleukin-8 (IL-8) were measured by enzyme-linked immunosorbent assay. Results The median (IQR) of TNF-α level on Day 5 was 5.08 (3.80–6.32) pg/ml, which was lower than on Day 14 (5.84 [4.91–9.14] pg/ml, p = 0.017), Day 30 (6.14 [3.82–7.67] pg/ml, p = 0.045), and Day 60 (5.60 [4.53–8.80] pg/ml, p = 0.009). On Day 60, subjects receiving inhaled corticosteroid (ICS) had a lower level of TNF-α than those who were not (4.82 [4.06–5.65] vs 7.66 [5.48–10.9] pg/ml, p = 0.02). EBC LTB4 level did not change significantly during recovery from AECOPD whereas IL-8 was mostly undetectable. Conclusions EBC TNF-α level was low in patients receiving systemic steroid and antibiotic therapy for AECOPD. These findings suggest a potential role for serial EBC TNF-α for non-invasive monitoring of disease activity.

Multi-Centre Assessment of the Spiegelberg Compliance Monitor: Interim Results

Analyses of a multi-centre database of 71 patients at risk of raised ICP showed that in head injured patients (n = 19) and tumour patients (n = 13) clear inverse relationships of ICP vs compliance exist. SAH patients (n = 5) appear to exhibit a biphasic relationship between ICP and compliance, however greater numbers of patients need to be recruited to this group. Patients with hydrocephalus (n = 34) show an initial decrease in compliance while ICP is less than 20 mmHg, thereafter compliance does not show a dependence upon ICP. A power analysis confirmed that sufficient numbers of patients have been recruited in the hydrocephalus group and a ROC analysis determined that a mean compliance value of 0.809 (lower and upper 95% CL = 0.725 & 0.894 resp.) was a critical threshold for raised ICP greater than 10 mmHg. Preliminary time-series analyses of the ICP and compliance data is revealing evidence that the cumulative time compliance is in a low compliance state (< 0.5 ml/mmHg), as a proportion of total monitoring time, increases more rapidly than the cumulative time ICP is greater than 25 mmHg. Before trials testing compliance thresholds can be designed, we need to consider not just the absolute threshold, but the duration of time spent below threshold. A survey may be required to identify a consensus of what is the minimum duration of raised ICP above 25 mmHg needed to instigate treatment.

Traumatic intracerebral haemorrhage: Is the CT pattern related to outcome?

It is believed by many neurosurgeons that in addition to age and neurological status, the CT patterns of traumatic intracerebral haemorrhages are related to outcome. The aim of this study was to find out whether this is the case. The study was conducted in a regional level I trauma centre in Hong Kong. We prospectively collected data of patients with traumatic intracerebral haematomas over a 4-year period. Of 464 patients with head injuries, traumatic intracerebral haematoma was significantly associated with inpatient mortality and one year unfavorable outcome after adjustment for age, sex, post-resuscitation GCS, and presence of acute subdural haematoma. One hundred-and-fourteen patients had traumatic intracerebral haematomas and were included for further analysis. The mean age was 49, the male to female ratio was 2 to 1, and the median Glasgow Coma Scale (GCS) score on admission was 12. Logistic regression analysis showed that age and GCS score/GCS motor component score were significant factors for inpatient mortality, one-year mortality and one-year outcome. There was an association between temporal haematomas and inpatient mortality, subdural haematomas and inpatient mortality, and bilateral haematomas and unfavourable one-year outcome. In patients with severe head injury, a traumatic haematoma of more than 50 ml was associated higher inpatient mortality. In addition to age and GCS score, the CT patterns of bilateral haematomas, temporal haematomas and associated subdural haematomas were suggestive of poor outcome or mortality.

Magnesium sulfate for brain protection during temporary cerebral artery occlusion.

We evaluated the effects of magnesium sulfate on brain tissue oxygen (PtO2) tension, carbon dioxide (PtCO2) tension and pH (pHt) in patients undergoing temporary artery occlusion for clipping of cerebral aneurysm. We studied 18 patients with aneurysmal subarachnoid hemorrhage. All patients received standard anesthetics using target controlled infusion of propofol (3 microg/ml) and remifentanil (10 ng/ml). After craniotomy, a calibrated multiparameter sensor (Neurotrend, Diametrics Medical, Minneapolis, MN) was inserted to measure PtO2, PtCO2 and pHt in tissue at risk of ischemia during temporary artery occlusion. Patients were then randomly allocated to receive either intravenous saline or magnesium 20 mmol over 10 min followed by an infusion 4 mmol/h. Plasma magnesium concentration, brain tissue gases and pHt were determined at baseline, 30 min after study drug infusion and 4 min after temporary clipping. Data were analyzed by factorial ANOVA with repeated measures. Intergroup difference was compared with unpaired t test. P value < 0.05 was considered significant. Patient characteristics, baseline brain tissue gases and pHt did not differ between groups. Magnesium infusion increased PtO2 by 34%. Following temporary artery occlusion, PtO2 and pHt decreased and PtCO2 increased in both groups. However, tissue hypoxia was less severe and the rate of PtO2 decline was slower in the magnesium group. Our data suggested that magnesium enhances tissue oxygenation and attenuates hypoxia during temporary artery occlusion.

Re-defining the ischemic threshold for jugular venous oxygen saturation--a microdialysis study in patients with severe head injury.

Neurological change is more likely to occur when jugular venous oxygen saturation (SjvO2) is less than 50%. However, the value indicating cellular damage has not been clearly defined. We determined the critical SjvO2 value below which intracerebral extracellular metabolic abnormalities occurred in 25 patients with severe head injury. All patients received standard treatment with normoventilation and maintenance of intracranial pressure < 20 mmHg. SjvO2 was measured from the dominant jugular bulb using a calibrated fibreoptic catheter. Intracerebral metabolic monitoring was performed by collecting perfusate from a microdialysis probe placed in the frontal lobe anterior to the intracranial catheter. Excitotoxin (glutamate) and other extracellular metabolites (lactate, glucose and glycerol) were measured frequently using enzymatic and colorimetric methods. We observed biphasic relationships between SjvO2 and all intracerebral metabolites. Analysis of variance showed that there were rapid increases in glutamate, glycerol and lactate when SjvO2 dropped below 40, 43 and 45% respectively. Extracellular glucose decreased when SjvO2 dropped below 42%. Our findings suggested that the ischemic threshold for SjvO2 in patients with severe head injury is 45%, below which secondary brain damage occurred.

Cerebral blood flow (CBF)-directed management of ventilated head-injured patients

OBJECTIVE Ischaemic brain damage has been shown to be an important contributing factor causing head injury fatality. Maintenance of an adequate cerebral perfusion pressure is difficult in patients with elevated intracranial pressure (ICP) and deranged cerebral vasoreactivity. Thirty-five cases of ventilated moderate-to-severe head-injured patients were prospectively studied, correlating their cerebral haemodynamic abnormalities, neurochemical disturbances (using microdialysis methodology) and clinical outcome. METHODS Cerebral haemodynamic abnormalities were defined and classified by transcranial Doppler ultrasonography (TCD) and stable xenon-CT cerebral blood flow measurements (XeCT) into their status of CO2 reactivity, pressure autoregulation, hyperaemia or non-hyperaemia. Two-hour episodes of these abnormalities with and without haemodynamic intervention were followed in their changes in ICP, CPP, intracerebral metabolites and finally their clinical outcome. RESULTS Loss of CO2 reactivity was associated with a significantly higher ICP, increasing intracerebral metabolites (lactate, glutamate and glycerol) and invariably a fatal outcome. Impaired pressure autoregulation was also associated with an elevated ICP, but no significant difference in intracerebral metabolites and incidence of favourable clinical outcome. Patients with intact CO2 reactivity and impaired pressure autoregulation were treated with an elevated CPP in 32 episodes, resulting in a significant reduction in ICP, intracerebral glutamate and glycerol and non-survival. In patients with intact CO2 reactivity and impaired pressure autoregulation, eleven episodes of hyperaemia were identified by XeCT. A modest 20%, blood pressure reduction resulted in a trend towards a reduction of ICP, intracerebral glutamate and glycerol and non-survival. CONCLUSIONS The need for haemodynamic intervention in this group of ventilated patients with moderate-to-severe head inury can be made logical when these abnormalities are identified daily. The success of management was reflected by a stable or improved ICP, CPP, intracerebral metabolic deranagement and survival.