Application of MVBC equation to predict mixed venous blood concentrations of sevoflurane in cardiac anaesthesia

We have proposed an equation for estimating the real-time mixed venous blood concentration (MVBC) of isoflurane in cardiac anaesthesia. However, information related to the application of our method to sevoflurane is lacking. We studied 12 patients undergoing cardiac surgery and anaesthetised with sevoflurane. At different time points, pulmonary arterial blood samples were collected for gas chromatography-mass spectrometry (GC-MS) to determine the real mixed venous concentrations of sevoflurane. The inspired and expired concentrations of sevoflurane, measured by a gas monitor, were used for the MVBC calculations. Using Bland-Altman analyses, we found that the calculated MVBCs accurately represent the actual concentrations of sevoflurane in pulmonary arterial blood, as shown by a near-zero percentage bias with a 0.14% precision between the two concentrations. The results demonstrated that our equation could be a useful method for estimating the pulmonary blood concentration of sevoflurane.

Use of convalescent plasma therapy in SARS patients in Hong Kong

In order to evaluate the efficacy of convalescent plasma therapy in the treatment of patients with severe acute respiratory syndrome (SARS), 80 SARS patients were given convalescent plasma at Prince of Wales Hospital, Hong Kong, between 20 March and 26 May 2003. Good outcome was defined as discharge by day 22 following the onset of SARS symptoms. Poor outcome was defined as death or hospitalization beyond 22 days. A higher day-22 discharge rate was observed among patients who were given convalescent plasma before day 14 of illness (58.3% vs 15.6%; P<0.001) and among those who were PCR positive and seronegative for coronavirus at the time of plasma infusion (66.7% vs 20%; P=0.001).

Endoscopic-guided adenoidectomy using a classic adenoid curette: a simple way to improve adenoidectomy

A total of 13 adenoidectomies using a nasal endoscopic-guided transoral adenoid curette (not yet a published standardised method) were performed to treat snoring. Nasal endoscopy allows easy assessment of the size of the adenoids and improves the accuracy of the adenoidectomy. This technique is particularly useful for paediatric patients who have small oral cavities. The assessment and excision of the adenoids in these cases are often difficult. Using the nasal endoscope, the curette can be accurately inserted at the superior border of the adenoid, allowing the complete transoral removal of the main bulk of the adenoid tissue. All 13 patients showed considerably decreased snoring and improvements in the quality of sleep as reported by the parents and the patients. We believe that nasal endoscopic-guided transoral adenoidectomy is a viable alternative to classic adenoidectomy. This technique also has the advantage of using commonly available simple ear, nose, and throat instruments.

Flavonoids from Blumea balsamifera

3,4',5-Trihydroxy-3',7-dimethoxyflavanone was isolated from the ligroin extract of the leaves of Blumea balsamifera, while the acetone extract yielded 3',4',5-trihydroxy-7-methoxyflavanone and a new biflavonoid identifed as 3-O-7''-biluteolin (1). The isolation of 1 is significant since a biflavonoid with a C-O-C linkage of the type [I-3-O-II-7] has not been previously reported from a plant.

A Real-Time Method for Estimating the Concentrations of Isoflurane in Mixed Venous Blood by a Derived Fick???s Equation

We propose an equation derived from Fick's laws and Lin's concept of effective blood concentration to calculate the blood concentration of inhaled anesthetics in mixed venous blood (MVBC) without direct blood sampling. We investigated the relationship between the calculated concentrations and the actual blood sample concentrations in mixed venous blood of patients undergoing cardiac surgery during isoflurane anesthesia in this study. Sixteen patients were recruited for Experiment 1. At different time points, pulmonary arterial blood samples were collected for gas chromatography/mass spectrometric determination via the pulmonary artery catheter: these samples represented the actual concentrations. The inspired and expired concentrations of isoflurane measured by a gas monitor were used for the MVBC calculations. Lin's effective blood concentration method was also used, and the obtained results were then compared with MVBC. Studies were conducted on 11 additional patients (Experiment 2) to confirm the results obtained from Experiment 1. The MVBC and the actual blood concentrations showed a similar kinetic pattern and level during anesthesia and had high correlation coefficients within subjects. We have demonstrated that MVBC could represent the actual pulmonary blood concentrations of isoflurane during cardiac surgery. The results suggest that MVBC could be a useful method of estimating the real-time pulmonary blood concentration of isoflurane. The clinical significance and importance of the method merit further investigation.

Direct detection of rifampin-resistant mycobacterium tuberculosis in respiratory specimens by PCR-DNA sequencing

This study evaluated the feasibility of a molecular strategy based on identification of Mycobacterium tuberculosis by IS6110 PCR or Cobas Amplicor PCR, and rpoB PCR-DNA sequencing of the 81-bp rifampin resistance determining region (RRDR) for direct detection of rifampin resistance in respiratory specimens. A collection of 2,138 respiratory specimens and 352 nonduplicate M. tuberculosis isolates (including 233 isolates from the evaluated respiratory specimens and an additional collection of 119 stored isolates) from Southern China was investigated. Using culture as the reference test, the overall diagnostic sensitivities of an acid-fast bacillus (AFB) smear, Cobas Amplicor PCR, IS6110 PCR were 54.5% (156 of 286), 86.7% (248 of 286), and 89.2% (255 of 286), respectively. The sensitivities of the rpoB PCR for the specimens with positive AFB smears and with positive PCR results in the IS6110 PCR and/or Cobas Amplicor PCR were 100% (156 of 156) and 92.3% (239 of 259), respectively. Of the 352 nonduplicate M. tuberculosis isolates, the agar proportion method for rifampin reported 39 resistant strains. Full agreement (352 of 352) was found with the agar proportion method and the genotype inferred from the rpoB DNA sequencing data for rifampin. Thirty-nine mutations of nine distinct kinds, eight point mutations, and one deletion within the RRDR were found in the 39 resistant strains. For the direct DNA sequencing performed on rpoB PCR-positive respiratory specimens, the concordance with the agar proportion method and the subsequent PCR-sequencing for the culture isolate was 100%. This strategy has potential application for direct and rapid diagnosis of rifampin-resistant M. tuberculosis in IS6110 PCR or Cobas Amplicor PCR-positive respiratory specimens.

Psychological distress and negative appraisals in survivors of severe acute respiratory syndrome (SARS)

BACKGROUND

Severe acute respiratory syndrome (SARS) is a novel disease. The authors have limited knowledge of its impact on mental health. The present study aimed to examine the level and extent of psychological distress of SARS survivors following 1-month recovery, to explore patients' negative appraisals of the impact of SARS, and to evaluate the associations between psychological distress and negative appraisals.

METHOD

The Beck Anxiety Inventory, the Beck Depression Inventory, and a newly developed measure, the SARS Impact Scale (SIS), were mailed to 453 Hong Kong Chinese SARS survivors discharged from hospital for 4 weeks or more.

RESULTS

A total of 425 patients received the questionnaires and 180 (mean age 36.9 years; 120 women) gave valid replies. The response rate was 42.4 %. The participants also represented 13.6 % of all adult survivors in Hong Kong. About 35 % of respondents reported 'moderate to severe' or 'severe' ranges of anxiety and/or depressive symptoms. It was found that those working as healthcare workers or having family members killed by SARS were more prone to develop subsequent high levels of distress. Factor analyses extracted three meaningful factors of the SIS, namely 'survival threat', 'physical impact', and 'social impact'. Negative appraisals at the acute phase and 1-month recovery significantly accounted for substantial portions of variances for anxiety and depressive symptoms, after the effects of other psychosocial variables were controlled.

CONCLUSIONS

Psychological distress of SARS survivors at 1-month recovery is real and significant. Negative appraisals may play a pivotal role in the development of psychological distress for SARS survivors, at least in the short term.

Carpal tunnel release

Endoscopic carpal tunnel release has the advantage over open release of reduced tissue trauma and postoperative morbidity. Limited open carpal tunnel release has also been shown to have comparable results, but is easier to perform and is safer. We have compared the results of both techniques in a prospective, randomised trial. Thirty patients with bilateral carpal tunnel syndrome had simultaneous bilateral release. The technique of release was randomly allocated to either two-portal endoscopic release (ECTR) or limited open release using the Strickland instrumentation (LOCTR).

The results showed that the outcome was similar at follow-up of one year using both techniques. However, the LOCTR group had significantly less tenderness of the scar at the second and fourth postoperative week (p < 0.01). There was also less thenar and hypothenar (pillar) pain after LOCTR. Subjective evaluation showed a preference for LOCTR.

Carpal tunnel release. A prospective, randomised study of endoscopic versus limited-open methods

Endoscopic carpal tunnel release has the advantage over open release of reduced tissue trauma and postoperative morbidity. Limited open carpal tunnel release has also been shown to have comparable results, but is easier to perform and is safer. We have compared the results of both techniques in a prospective, randomised trial. Thirty patients with bilateral carpal tunnel syndrome had simultaneous bilateral release. The technique of release was randomly allocated to either two-portal endoscopic release (ECTR) or limited open release using the Strickland instrumentation (LOCTR). The results showed that the outcome was similar at follow-up of one year using both techniques. However, the LOCTR group had significantly less tenderness of the scar at the second and fourth postoperative week (p < 0.01). There was also less thenar and hypothenar (pillar) pain after LOCTR. Subjective evaluation showed a preference for LOCTR.

Inferior vena caval filters following deep vein thrombosis in patients with ruptured intracranial aneurysm

Anticoagulant therapy is highly effective and prevents death in more than 95% of patients who have suffered pulmonary embolism following deep vein thrombosis. Inferior vena caval filters provide an alternative to full anticoagulation in those patients at highest risk of catastrophic haemorrhagic complications. We report on two patients who developed deep vein thrombosis following ruptured unsecured intracranial aneurysms. Inferior vena caval filters were inserted prior to aneurysm clipping, as a prophylactic measure to prevent pulmonary embolism while awaiting surgery. The patients did not receive anticoagulant therapy following successful clipping of the aneurysm. Both patients had clinical resolution of the lower limb swelling and no radiological evidence of propagation of the thrombus. During 18 months of follow-up there were no complications and no evidence of post-thrombotic syndrome.

Closed retrograde nailing of pathological humeral fractures

We treated 19 patients with 21 pathological humeral fractures secondary to metastatic disease. All patients were stabilized using retrograde Ender's nails. Open reduction was required in one patient and mean operative time was 40 min (range 30-65 min). All patients retained satisfactory elbow and shoulder function while 16 patients reported good pain relief. Functional recovery was rated as good in 15 patients, fair in three, and poor in one. In our experience the retrograde technique using Ender's nails provides secure stabilization with minimal morbidity, minimal blood loss, and short operative time, and is well suited for this category of patients.

Genetic structure of three orchid species with contrasting breeding systems using RAPD and allozyme markers

Zeuxine gracilis, Zeuxine strateumatica, and Eulophia sinensis are wild orchids with different breeding systems and colonizing abilities. Zeuxine gracilis is an outcrosser with restricted distribution, whereas S. strateumatica is an apomictic colonizer found only in newly available open habitats. Eulophia sinensis is an outcrossing colonizer. This study investigates the levels of genetic variation and patterns of population structure in these wild orchids to provide genetic information for the development of suitable conservation strategies. Lack of allozyme variation was characteristic of all three species, especially in populations of the two colonizing orchids, Z. strateumatica and E. sinensis. More variable markers, randomly amplified polymorphic DNAs (RAPDs), were further employed to characterize population structure of these species. Substantial genetic variation was found at the RAPD loci within populations of Z. gracilis (p = 21.65 ± 15.88%, A = 1.217 ± 0.159, and H = 0.076 ± 0.054) and E. sinensis (p = 17.82 ± 20.97%, A = 1.179 ± 0.209, and H = 0.070 ± 0.084), but little variation existed within populations of Z. strateumatica (p = 2.84 ± 2.58%, A = 1.029 ± 0.026, and H = 0.011 ± 0.011). Regardless of the breeding system, the total gene diversity at the species level was partitioned primarily between populations, as shown by high G(ST) values, in all three species. An extremely high level of population differentiation (G(ST) = 0.924) was found in the apomictic colonizer Z. strateumatica. The patterns of genetic variation in these wild orchids are apparently related to their differences in breeding system and colonizing ability. Different conservation strategies are needed for the long-term survival of these species.

Molecular mimicry: anti-DNA antibodies may arise inadvertently as a response to antibodies generated to microorganisms

The origin of anti-DNA antibodies remains speculative. We argue that some of these antibodies may arise inadvertently in nature during the course of a normal immune response due to their induction by antibodies which bear structures (mimotopes) that mimic DNA. These antibodies are not necessarily DNA specific but, like the T15 idiotype (id)-positive antibodies which bind to phosphorylcholine, are produced normally to some environmental or microbial antigen. Such a mimotope was found in a T15(+) antibody at the highly specific region encoded principally by the D gene, DFL16.1. This mimotope was also found in human antibodies that are encoded by DXP'1, the human counterpart of DFL16.1 and which is used commonly in anti-DNA antibodies. The mimotope is closely related to the epitope responsible for the T15 id and appears to be cryptic or normally hidden in the native protein. The existence of such a common, conserved sequence raises questions about how easily anti-DNA antibodies can be generated in nature and what purpose these proteins may serve. Molecular mimicry with regard to autoimmunity must thus be viewed as existing not necessarily between the infectious agent and self-antigens, but also between the antibodies induced by the organism and the self-antigens.

Excitatory amino acid receptor antagonist 2APH may improve local CBF during cerebral ischemia in cats

BACKGROUND

The present study was designed to investigate in a focal cerebral ischemia model the influence of 2APH, a competitive NMDA receptor antagonist, on the cerebral blood flow of cat cortex, given intravenously before cerebral ischemia.

METHODS

Thirty-four male cats weighing 2.5 to 3.5 kg were anesthetized with halothane and then randomly assigned to either control or experimental group. In the experimented group 18 cats were treated with 2APH and in the control group 16 cats were given saline 10 min before middle cerebral artery occlusion (MCAO). Cortical blood flow (CBF), determined by laser Doppler ultrasound flowmetry, was measured 1 h, 2 h, 3 h, 4 h and 5 h after occlusion. Infarct volume was calculated by summing up the areas in each stained brain section after the experiment.

RESULTS

There was a significant difference in the infarct volume of cortex between the 2APH group and the saline control group (P < 0.05). Moreover, we did notice an apparent decrease of the infarct volume in basal ganglia area when 2APH was given (P < 0.01). The total infarct volume was significantly smaller in the group treated with 2APH after MCAO as compared with the saline control group (P < 0.01).

CONCLUSIONS

The data from the present experiment suggest that NMDA antagonists may not only antagonize the neurotoxic effect of excitatory amino acid on ischemic neuron but also improve the CBF of ischemic brain.

Medical informatics--the state of the art in the Hospital Authority

Since its inception in 1990, the Hospital Authority (HA) has strongly supported the development and implementation of information systems both to improve the delivery of care and to make better information available to managers. This paper summarizes the progress to date and discusses current and future developments. Following the first two phases of the HA information technology strategy the basic infrastructural elements were laid in place. These included the foundation administrative and financial systems and databases; establishment of a wide area network linking all hospitals and clinics together; laboratory, radiology and pharmacy systems with access to results in the ward. A major push into clinical systems began in 1994 with the clinical management system (CMS), which established a clinical workstation for use in both ward and ambulatory settings. The CMS is now running at all major hospitals, and provides single logon access to almost all the electronically collected clinical data in the HA. The next phase of development is focussed on further support for clinical activities in the CMS. Key elements include the longitudinal electronic patient record (ePR), clinical order entry, generic support for clinical reports, broadening the scope to include allied health and the rehabilitative phase, clinical decision support, an improved clinical documentation framework, sharing of clinical information with other health care providers and a comprehensive data repository for analysis and reporting purposes.

The effect of intraischemic mild hypothermia on focal cerebral ischemia/reperfusion injury

BACKGROUND

The protective role of intraischemic mild hypothermia on brain injury associated with cerebral ischemia/reperfusion was investigated using a localized, no-flow cerebral ischemia/reperfusion model in rats in vivo.

METHODS

Male Wistar rats weighing 250-350 g were anesthetized lightly with halothane. All rats were randomly allocated into two series experiments the first of which was for study of infarct volume and the second of which was for study of NO (nitric oxide) content, and then subjected to various time intervals of focal ischemia followed by reperfusion. The intraischemic mild hypothermia was induced by feedback-regulated semiconductor cooling block in a group of these rats. Normothermia groups were considered as the control groups. The infarct volume and the NO content of rat brain were measured in different groups and hours respectively.

RESULTS

The infarct volume of mild hypothermia group was significantly different from that of normal control group within the time window of 10 min (P < 0.05), infarcted brain volumes in hypothermic rats were significantly smaller than in normothermic rats, for the time window of 1 h there was no significant difference in the infarct volume between mild hypothermic group and normothermic control group (P > 0.5). Furthermore, increased tissue levels of NO, a potential mediator of cerebral injury in the brain following focal ischemia were depressed by mild hypothermia.

CONCLUSIONS

It is suggested that localized mild hypothermia may be a protective against focal cerebral ischemia/reperfusion injury and that the decreased nitric oxide production in the brain may serve as the protective mechanism of hypothermia.