Unavoidable Extinctions in Ecosystems of Extreme Isolation

Future systems of extreme isolation, including initiatives in space exploration, may require the services of onboard ecosystems. Biosphere 2, which ran between 1991 and 1993, aspired to mimic the earthly ecosystem and assess the ability of humans and other species to survive in a fully enclosed space. In this study, the data for plant species survival in the tropical rainforest sector from the first 2-year mission were studied through the prism of the neutral theory of biodiversity (NTB), which predicts how closed communities develop and how they lose species due to random demographic effects. Biosphere-2 lost species faster than a neutral process would predict. The specific reasons have been well documented, but the integrated approach of NTB offers new insights. It predicts that a closed ecological community must lose species and there is a specific time frame for this. To test it properly, the operation time of Biosphere-2 should have been at least 30 times greater. The new insights that NTB brings to the story of Biosphere 2 could be important for microcosm studies in general. A similar analysis suggests that the operation and testing time of other simulated ecosystems should also be increased.

P-154 GIANT HIATAL HERNIAS: LAPAROSCOPIC REPAIR WITH OR WITHOUT MESH PLACEMENT; EXPERIENCE OF A SINGLE CENTER IN NORTHERN GREECE

Aim

Α giant hiatal hernia is defined as a type III paraesophageal hernia, where more than 30% of the stomach lies within the thoracic cavity, with or without any other abdominal viscera, such as pancreas, spleen, or colon. It suggests a rare clinical entity, accounting for less than 0,3% of all hiatal hernias. As a consequence, the surgical treatment, and in particular the laparoscopic approach, is considered challenging and demanding. The purpose of this study is to prove, through our center's experience, that the laparoscopic approach is a safe and effective method of giant hiatal hernia repair.

Material and Methods

8 patients, 4 men and 4 women, 63,83 years old on average, with giant hiatal hernias, are included in this study. In all cases, laparoscopic hiatal hernia repair was performed, without any conversions, in combination with Nissen fundoplication. In addition, in three cases, a poly-4-hydroxybutyrate mesh (Phasix) was applied.

Results

Two patients were reoperated, one due to persistant dysphagia and one due to ileus. The rest of the patients followed an uneventful postoperative course with a short hospital stay and elimination of their symptoms, during a 12-month follow-up period.

Conclusions

Laparoscopic repair of giant hiatal hernias suggests is a challenging operation, which is accompanied by high morbidity and recurrence rates, up to 12% and 10% respectively, as reported in the literature. However, it is a safe and effective procedure when performed in experienced centers.