The classification of freezing cold injuries - a NATO research task group position paper

INTRODUCTION

Freezing cold injuries (FCI) are a common risk in extreme cold weather operations. Although the risks have long been recognised, injury occurrences tend to be sparse and geographically distributed, with relatively few cases to study in a systematic way. The first challenge to improve FCI medical management is to develop a common nomenclature for FCI classification. This is critical for the development of meaningful epidemiological reports on the magnitude and severity of FCI, for the standardisation of patient inclusion criteria for treatment studies, and for the development of clinical diagnosis and treatment algorithms.

METHODOLOGY

A scoping review of the literature using PubMed and cross-checked with Google Scholar, using search terms related to freezing cold injury and frostbite, highlighted a paucity of published clinical papers and little agreement on classification schemes.

RESULTS

A total of 74 papers were identified, and 28 were included in the review. Published reports and studies can be generally grouped into four different classification schemes that are based on (1) injury morphology; (2) signs and symptoms; (3) pathophysiology; and (4) clinical outcome. The nomenclature in the different classification systems is not coherent and the discrete classification limits are not evidence based.

CONCLUSIONS

All the classification systems are necessary and relevant to FCI medical management for sustainment of soldier health and performance in cold weather operations and winter warfare. Future FCI reports should clearly characterise the nature of the FCI into existing classification schemes for surveillance (morphology, symptoms, and appearance), identifying risk-factors, clinical guidelines, and agreed inclusion/exclusion criteria for a future treatment trial.

Review of prognostic factors for kidney transplant survival

Transplantation is the most effective treatment for end-stage chronic kidney disease, as this procedure prolongs and improves the patient's quality of life. One of the key problems is the risk of graft rejection. The purpose of this research was to identify and analyse prognostic factors that will prevent rejection. In particular, the prognostic factors grouped by methods of synthesis, generalisation and statistical processing with calculation and graphical representation of hazard ratio and correlation coefficient were grouped, namely: age of donor and recipient, time of cold kidney ischaemia, duration of preoperative dialysis, body mass index, presence of concomitant diseases (diabetes mellitus, hypertension), primary causes causing transplantation. Several molecular genetic and biochemical prognostic markers (transcription factors, immunocompetent cell signalling and receptors, cytostatin C, creatinine, citrate, lactate, etc.) are annotated. It has been demonstrated that creatinine reduction rate determines the risk of rejection, displaying the dynamics of cystatin C and creatinine changes in the postoperative period. Young recipients who underwent prolonged preoperative dialysis were identified as having the highest risk of rejection. Diabetes and hypertension bear a non-critical but commensurately equal risk of rejection. The survival rate of the graft is better when transplanted from a living donor than from a deceased donor. A correlation between cold ischaemia time, body mass index and the probability of graft failure has been proven, namely, the greater the donor and recipient body mass index and the longer the cold ischaemia time, the lower the chance of successful long-term organ acclimation. The data obtained can be used as prognostic factors for graft accommodation at different intervals after surgery.

Effect of positive cumulative fluid balance on postoperative complications after living donor liver transplantation: A retrospective analysis

Background and Aims:

Fluid administration during liver transplant (LT) surgery is controversial. Although adverse outcomes following positive intraoperative fluid balance have been reported, studies presenting the influence of cumulative postoperative fluid balance (CFB) on complications following LT are sparse. Patients with chronic liver disease tend to receive more fluid during and after surgery due to their unique physiological disease state. The aim of this study was to evaluate the influence of 48-hour CFB on the development of acute kidney injury (AKI) and pulmonary complications on day 4 after live donor LT.

Methods:

This retrospective study included 230 patients undergoing live donor LT. The effect of CFB on day 2 on AKI and pulmonary complications was analysed. Chi-square test, Fisher's exact test, samples t-test, Mann-Whitney U-test were used.

Results:

Bivariate analysis showed a lower graft vs recipient weight ratio (GRWR), sepsis (P < 0.001) and a higher 48-hour CFB after surgery significantly increased the development of AKI. For pulmonary complications, higher Model for End- stage Liver Disease-Na(MELD-Na) score, higher peak arterial lactate, higher 48-hour CFB (P = 0.016) and sepsis (P = 0.003) were found to be statistically significant. Upon multivariate analysis, CFB at 48 hours was significantly higher in patients suffering from pulmonary complications, and GRWR and sepsis were significant for AKI. For every one litre increase in CFB on day 2, the odds of pulmonary complications increased by 37%.

Conclusion:

A more positive CFB on day 2 increased the development of pulmonary complications and lower GRWR and sepsis increased the development of AKI.

Experimental isolation and preservation of solid organs before transplantation: effects of pretreatment using four different molecules

OBJECTIVES

In transplantation surgery, the ischaemic organ and reperfusion impairment after cold storage remains a considerable risk factor for impaired function and potential failure of the grafted organ. Substantial logistical efforts have been undertaken to reduce the cold ischaemic time because the demand for available transplant organs and the periods of cold ischaemia are increasing.

METHODS

Four molecules were investigated (erythropoietin, sildenafil, lazaroid [U74389G], octreotide) in individual intravenous infusions 1 hour before the organ was harvested. This study was performed in 30 healthy landrace/large-white pigs (male; >10 weeks old; average weight, 22 ± 2 kg) in groups of six. The organs were studied at harvest, and at 8 and 24 hours post-harvest.

RESULTS

The lazaroid molecule increased malondialdehyde (MDA) levels in the liver and pancreas at 8 hours. Hepatic lazaroid molecules improved liver histology at 8 and 24 hours. For kidneys, erythropoietin had a positive effect at 24 hours post-harvest. For the pancreas, octreotide showed better performance. In the lungs, there was less interstitial oedema with erythropoietin and lazaroid compared with the control group at 8 hours post-harvest.

CONCLUSION

All molecules had a positive effect and decreased ischaemia/reperfusion graft injury. Thus, pretreatment before organ harvest has a beneficial role.

Beneficial effects of the novel marine oxygen carrier M101 during cold preservation of rat and human pancreas

Ischaemia impairs organ quality during preservation in a time‐dependent manner, due to a lack of oxygen supply. Its impact on pancreas and islet transplantation outcome has been demonstrated by a correlation between cold ischaemia time and poor islet isolation efficiency. Our goal in the present study was to improve pancreas and islet quality using a novel natural oxygen carrier (M101, 2 g/L), which has been proven safe and efficient in other clinical applications, including kidney transplantation, and for several pre‐clinical transplantation models. When M101 was added to the preservation solution of rat pancreas during ischaemia, a decrease in oxidative stress (ROS), necrosis (HMGB1), and cellular stress pathway (p38 MAPK)activity was observed. Freshly isolated islets had improved function when M101 was injected in the pancreas. Additionally, human pancreases exposed to M101 for 3 hours had an increase in complex 1 mitochondrial activity, as well as activation of AKT activity, a cell survival marker. Insulin secretion was also up‐regulated for isolated islets. In summary, these results demonstrate a positive effect of the oxygen carrier M101 on rat and human pancreas during preservation, with an overall improvement in post‐isolation islet quality.

Minimising cold ischaemic time is essential in cardiac death donor-associated liver transplantation

BACKGROUND

An important issue in the transplantation of livers procured from cardiac death donors (CDDs) concerns why some centres report equivalent outcomes and others report inferior outcomes in transplantations using CDD organs compared with standard criteria donor (SCD) organs. Resolving this discrepancy may increase the number of usable organs.

OBJECTIVES

This study aimed to test whether differences in cold ischaemic time (CIT) are critical during CDD organ transplantation and whether such differences might explain the disparate outcomes.

METHODS

Results of CDD liver transplants in our own centre were compared retrospectively with results in a matched cohort of SCD liver recipients. Endpoints of primary non-function (PNF) and ischaemic cholangiopathy (IC) were used because these outcomes are clearly associated with CDD organ use.

RESULTS

In 22 CDD organ transplants, CIT was a strong predictor of PNF or IC (P = 0.021). Minimising CIT in CDD organ transplants produced outcomes similar to those in a matched SCD organ transplant cohort at our centre and in SCD organ transplant results nationally (1- and 3-year graft and patient survival rates: 90.9% and 73.3% vs. 77.6% and 69.2% in CDD and SCD grafts, respectively. A review of the published literature demonstrated that centres with higher CITs tend to have higher rates of PNF or IC (correlation coefficient: 0.41).

CONCLUSIONS

These findings suggest that a targeted effort to minimise CIT might improve outcomes and allow the safer use of CDD organs.