Does mild heat combined with external stenting prevent from intimal hyperplasia and medial thickening in the venous grafts? Experimental study

Introduction. Intimal hyperplasia and medial thickening of the venous grafts used in coronary artery bypass grafting (CABG) often leads to wall thickening and ultimately to conduit occlusion. The purpose was to investigate the effects of mild heat (85°C) followed by utilization of restrictive sleeve on histological changes of the venous grafts implanted into an arterial system. Material and methods. Reversed external jugular vein interposition grafting of the carotid artery on the mongrel dogs (n = 18) was performed. The experimental animals were split into three groups: H (n = 6) - grafts were exposed to mild heat and an external sleeve was placed around, S (n = 6) - grafts only with the sleeve and C (n = 6) - control group. The grafts were explanted after 3 months. Prior to explantation the grafts&#8217; patency was checked using flowmeter. Afterwards harvested veins were examined in light (LM), scanning (SEM) and transmission electron microscope (TEM). Cross-sectional intima (IA), media (MA) and relative intima area (RIA) for all grafts were calculated. Tissue samples from all grafts before implantation (harvested veins and veins after exposition to mild heat) were also examined. Results. Mild heat destroyed endothelial cells (ECs) and, to a lesser degree, basement membrane but did not influence IA, MA and RIA values. Medial smooth muscle cells (SMCs) located closer to the adventitia were affected by heat pretreatment. After 3 months all grafts were patent. Intimal hyperplasia was observed in group S and C, but not in H. Intimal area was markedly higher (p < 0.05) in group S (1.97 &plusmn; 0.57 mm2) and C (1.51 &plusmn; 0.77 mm2) than in H (0.38 &plusmn; 0.08 mm2). Scanning scans 3 months after implantation showed the luminal surface of all grafts was mostly covered by ECs. Smoth muscle cells were present in the intima of all grafts in group C and S, not in H. Some of them were active synthetic type SMCs with many mitochondria and well developed Golgi apparatus (TEM). The media was atrophic in group H and S, where collagen bundles were dissociated, the collagen fibers disrupted and in random orientation in the matrix. Media area was significantly higher (p < 0.05) in group C (2.64 &plusmn; 0.32 mm2) than in S (1.71 &plusmn; 0.45 mm2) and H (1.74 &plusmn; 0.48 mm2). Conclusion. Mild heat pre-treatment and external sleeving may mitigate the formation of intimal hyperplasia and reduce medial thickening after implantation in the arterial circulation.Introduction. Intimal hyperplasia and medial thickening of the venous grafts used in coronary artery bypass grafting (CABG) often leads to wall thickening and ultimately to conduit occlusion. The purpose was to investigate the effects of mild heat (85°C) followed by utilization of restrictive sleeve on histological changes of the venous grafts implanted into an arterial system. Material and methods. Reversed external jugular vein interposition grafting of the carotid artery on the mongrel dogs (n = 18) was performed. The experimental animals were split into three groups: H (n = 6) - grafts were exposed to mild heat and an external sleeve was placed around, S (n = 6) - grafts only with the sleeve and C (n = 6) - control group. The grafts were explanted after 3 months. Prior to explantation the grafts&#8217; patency was checked using flowmeter. Afterwards harvested veins were examined in light (LM), scanning (SEM) and transmission electron microscope (TEM). Cross-sectional intima (IA), media (MA) and relative intima area (RIA) for all grafts were calculated. Tissue samples from all grafts before implantation (harvested veins and veins after exposition to mild heat) were also examined. Results. Mild heat destroyed endothelial cells (ECs) and, to a lesser degree, basement membrane but did not influence IA, MA and RIA values. Medial smooth muscle cells (SMCs) located closer to the adventitia were affected by heat pretreatment. After 3 months all grafts were patent. Intimal hyperplasia was observed in group S and C, but not in H. Intimal area was markedly higher (p < 0.05) in group S (1.97 &plusmn; 0.57 mm2) and C (1.51 &plusmn; 0.77 mm2) than in H (0.38 &plusmn; 0.08 mm2). Scanning scans 3 months after implantation showed the luminal surface of all grafts was mostly covered by ECs. Smoth muscle cells were present in the intima of all grafts in group C and S, not in H. Some of them were active synthetic type SMCs with many mitochondria and well developed Golgi apparatus (TEM). The media was atrophic in group H and S, where collagen bundles were dissociated, the collagen fibers disrupted and in random orientation in the matrix. Media area was significantly higher (p < 0.05) in group C (2.64 &plusmn; 0.32 mm2) than in S (1.71 &plusmn; 0.45 mm2) and H (1.74 &plusmn; 0.48 mm2). Conclusion. Mild heat pre-treatment and external sleeving may mitigate the formation of intimal hyperplasia and reduce medial thickening after implantation in the arterial circulation

Tension pneumothorax as a severe complication of endobronchial ultrasound-guided transbronchial fine needle aspiration of mediastinal lymph nodes

This article presents a case report of a patient suffering from bullous emphysema and chronic obstructive pulmonary disease, who was diagnosed with tension pneumothorax after undergoing endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). Tension pneumothorax is a severe but rare complication of EBUS-TBNA. It can result from lung injury caused by the biopsy needle or, in patients suffering from bullous emphysema, from spontaneous rupture of an emphysematous bulla resulting from increased pressure in the chest cavity during cough caused by bronchofiberoscope insertion. The authors emphasize that patients should be carefully monitored after the biopsy, and, in the case of complications, provided with treatment immediately in proper hospital conditions. Patients burdened with a high risk of complications should be identified before the procedure and monitored with extreme care after its completion

Severe hypothermia management in mountain rescue : a survey study

Introduction: Severe hypothermia is a rare but demanding medical emergency. Although mortality is high, if well managed, the neurological outcome of survivors can be excellent. The aim of the study was to assess whether mountain rescue teams (MRTs) are able to meet the guidelines in the management of severe hypothermia, regarding their equipment and procedures. Methods: Between August and December 2016, an online questionnaire, with 24 questions to be completed using Google Forms, was sent to 123 MRTs in 27 countries. Results: Twenty-eight MRTs from 10 countries returned the completed questionnaire. Seventy-five percent of MRTs reportedly provide advanced life support (ALS) on-site and 89% are regularly trained in hypothermia management. Thirty-two percent of MRTs transport hypothermic patients in cardiac arrest to the nearest hospital instead of an Extracorporeal Life Support facility; 39% are equipped with mechanical chest compression devices; 36% measure core body temperature on-site and no MRT is equipped with a device to measure serum potassium concentration on-site in avalanche victims. Conclusions: Most MRTs are regularly trained in the treatment of severe hypothermia and provide ALS. The majority are not equipped to follow standard procedural guidelines for the treatment of severely hypothermic patients, especially with cardiac arrest. However, the low response rate—23% (28/123)—could have induced a bias

Should capnography be used as a guide for choosing a ventilation strategy in circulatory shock caused by severe hypothermia? : observational case-series study

BACKGROUND: Severe accidental hypothermia can cause circulatory disturbances ranging from cardiac arrhythmias through circulatory shock to cardiac arrest. Severity of shock, pulmonary hypoperfusion and ventilation-perfusion mismatch are reflected by a discrepancy between measurements of CO(2) levels in end-tidal air (EtCO(2)) and partial CO(2) pressure in arterial blood (PaCO(2)). This disparity can pose a problem in the choice of an optimal ventilation strategy for accidental hypothermia victims, particularly in the prehospital period. We hypothesized that in severely hypothermic patients capnometry should not be used as a reliable guide to choose optimal ventilatory parameters. METHODS: We undertook a pilot, observational case-series study, in which we included all consecutive patients admitted to the Severe Hypothermia Treatment Centre in Cracow, Poland for VA-ECMO in stage III hypothermia and with signs of circulatory shock. We performed serial measurements of arterial blood gases and EtCO(2), core temperature, and calculated a PaCO(2)/EtCO(2) quotient. RESULTS: The study population consisted of 13 consecutive patients (ten males, three females, median 60 years old). The core temperature measured in esophagus was 20.7–29.0 °C, median 25.7 °C. In extreme cases we have observed a Pa-EtCO(2) gradient of 35–36 mmHg. Median PaCO(2)/EtCO(2) quotient was 2.15. DISCUSSION AND CONCLUSION: Severe hypothermia seems to present an example of extremely large Pa-EtCO(2) gradient. EtCO(2) monitoring does not seem to be a reliable guide to ventilation parameters in severe hypothermia