Acute compartment syndrome (ACS) is a progressive form of muscle ischaemia that is a surgical emergency and can have detrimental outcomes for patients if not treated optimally. The current problem is that there is no clear diagnostic threshold for ACS or guidance as to when fasciotomies should be performed. A new diagnostic method(s) is necessary to provide real-time information about the extent of muscle ischaemia in ACS. Given that lactic acid is produced by cells through anaerobic respiration, it may be possible to measure H+ ion concentration and to use this as a measure of ischaemia within muscle. Although we are familiar with the key biochemical metabolites involved in ischaemia; and the use of viability dyes in cell culture to distinguish between living or dead cells is well recognised; research has not been undertaken to correlate the biochemical and histological findings of ischaemia in skeletal muscle biopsies. Our primary aim was to investigate the potential for viability dyes to be used on live skeletal muscle biopsies (explants). Our secondary aim was to correlate the intramuscular pH readings with muscle biopsy viability. Nine euthanised Wistar rats were used. A pH catheter was inserted into one exposed gluteus medius muscles to record real-time pH levels and muscle biopsies were taken from the contralateral gluteus medius at the start of experiment and subsequently at every 0.1 of pH unit drop. Prior to muscle biopsy, the surface of the gluteus medius was painted with a layer of 50µmol/l Brilliant blue FCF solution to facilitate biopsy orientation. A 4mm punch biopsy tool was used to take biopsies. Each muscle biopsy was placed in a base mould filled with 4% ultra-low melting point agarose. The agarose embedded tissue block was sectioned to generate 400 micron thick tissue slices with a vibratome. The tissue slices were then placed in the staining solution with Hoechst 33342, Ethidium homodimer-1 and Calcein am. The tissue slices were imaged with Zeiss LSM880 confocal microscope's Z stack function. A dead muscle control was created by adding TritonX-100 to other tissue slices. For quantitative analyses, the images were analysed in Image J using the selection tool. This permitted individual cells to be identified and the mean grey value of each channel to be defined. Using the dead control, we were able to identify the threshold value for living cells using the Calcein AM channel.Abstract
Objectives
Methods
Progressive muscle ischaemia results in reduced aerobic respiration and increased anaerobic respiration, as cells attempt to survive in a hypoxic environment. Acute compartment syndrome (ACS) is a progressive form of muscle ischaemia that is a surgical emergency resulting in the production of Lactic acid by cells through anaerobic respiration. Our previous research has shown that it is possible to measure H+ ions concentration (pH) as a measure of progressive muscle ischaemia (in vivo) and hypoxia (in vitro). Our aim was to correlate intramuscular pH readings and cell viability techniques with the intramuscular concentration of key metabolic biomarkers [adenosine triphosphate (ATP), Phosphocreatine (PCr), lactate and pyruvate], to assess overall cell health in a hypoxic tissue model. Nine euthanised Wistar rats were used in a non-circulatory model. A pH catheter was used to measure real-time pH levels from one of the exposed gluteus medius muscles, while muscle biopsies were taken from the contralateral gluteus medius at the start of the experiment and subsequently at every 0.1 of a pH unit decline. The metabolic biomarkers were extracted from the snap frozen muscle biopsies and analyzed with standard fluorimetric method. Another set of biopsies were stained with Hoechst 33342, Ethidium homodimer-1 and Calcein am and imaged with a Zeiss LSM880 confocal microscope.Abstract
Background
Methods
There is currently no consensus about the mean
volume of blood lost during spinal tumour surgery and surgery for metastatic
spinal disease. We conducted a systematic review of papers published
in the English language between 31 January 1992 and 31 January 2012.
Only papers that clearly presented blood loss data in spinal surgery
for metastatic disease were included. The random effects model was
used to obtain the pooled estimate of mean blood loss. We selected 18 papers, including six case series, ten retrospective
reviews and two prospective studies. Altogether, there were 760
patients who had undergone spinal tumour surgery and surgery for
metastatic spinal disease. The pooled estimate of peri-operative
blood loss was 2180 ml (95% confidence interval 1805 to 2554) with catastrophic
blood loss as high as 5000 ml, which is rare. Aside from two studies
that reported large amounts of mean blood loss (>
5500 ml), the
resulting funnel plot suggested an absence of publication bias.
This was confirmed by Egger’s test, which did not show any small-study
effects
(p = 0.119). However, there was strong evidence of heterogeneity
between studies (I2 = 90%; p <
0.001). Spinal surgery for metastatic disease is associated with significant
blood loss and the possibility of catastrophic blood loss. There
is a need to establish standardised methods of calculating and reporting
this blood loss. Analysis should include assessment by area of the
spine, primary pathology and nature of surgery so that the amount
of blood loss can be predicted. Consideration should be given to
autotransfusion in these patients. Cite this article:
