Capnographic documentation of nasoesophageal and nasogastric feeding tube placement in dogs

Objective: To evaluate the ability of capnography to document proper placement of nasoesophageal (NE) and nasogastric (NG) feeding tubes. This study was conducted in 3 phases. Phase I of this study was designed in order to test the efficacy of capnography to distinguish placement of a feeding tube in the alimentary tract versus the respiratory tract. Phase II was designed in order to document that carbon dioxide (CO₂) could be measured through a polyvinyl chloride (PVC) feeding tube. Phase III was performed in order to evaluate the technique of continuous monitoring during insertion of the feeding tube into the esophagus and stomach as would be performed during a clinical‐tube placement. Design: Prospective study. Setting: Research laboratory. Animals: 24 adult dogs. Interventions: In Phase I, sedated dogs were instrumented with an intratracheal catheter and an 8 French feeding tube placed nasally into the distal esophagus and later advanced into the stomach. In Phase II, dogs were anesthetized and an 8 French feeding tube was placed down the endotracheal tube, then into the esophagus and later advanced into the stomach. In Phase III, sedated dogs were instrumented with an 8 French feeding tube inserted intranasally and then advanced to the level of the nasopharynx, distal esophagus and, lastly, the stomach. Fluoroscopy was used in order to determine location of the feeding tube. Measurements and main results: Phase I measurements included respiratory rate and CO₂ from the trachea, esophagus, and stomach and pH of gastric fluid sample. Phase II measurements included respiratory rate and CO₂ from the endotracheal tube, feeding tube in the endotracheal tube, feeding tube in the distal esophagus, and feeding tube in the stomach. Phase III data collection included respiratory rate and CO₂ as the tube was passed through the nasal cavity, nasopharynx, esophagus and stomach. Phase I fluid samples were collected from 5 of the 9 dogs and had pH values from 1.68 to 4.20. In both phases, values for the respiratory rate and CO₂ from the esophagus and stomach were 0 ± 0, significantly lower (P < 0.001) than the values from the trachea. In Phase II, there was no significant difference between the respiratory rates (P = 0.886) and CO₂ (P = 0.705) readings obtained from the endotracheal tube compared to readings from the feeding tube in the endotracheal tube. In Phase III, there was a significant difference (P < 0.001) between the respiratory rates and CO₂ readings obtained from the nasal cavity and the nasopharynx when compared to those readings obtained from the esophagus and stomach. Measurement of CO₂ and respiratory rate resulted in a reading of 0 every time the feeding tube was in the esophagus or stomach. Conclusions: Capnography may be used in order to detect airway placement of NE and NG tubes.     

The effects of aquaculture on bottlenose dolphin (Tursiops sp.) ranging in Shark Bay, Western Australia

The increasing presence of aquaculture in coastal waters calls for a better understanding of its environmental effects. Currently little information is available on the impact of shellfish farms on cetaceans. Here we compare long-term ranging patterns of adult female bottlenose dolphins (Tursiops sp. in Shark Bay, Western Australia) before and during full-scale pearl oyster farming operations, to determine if they were displaced. When the exact location of the oyster farm was determined, the dolphins decreased their use of that area after the farm was in place. Tracks of adult female dolphin movement near the oyster farm were compared to tracks of dolphin movement near an ecologically similar area where no oyster farm existed. Tracks near the oyster farm were less likely to enter the oyster farm itself than tracks near an ecologically similar location. This suggests that shellfish aquaculture could have a large impact on small cetaceans. The analytical techniques discussed apply broadly to aquatic and terrestrial animals.     

Characterization of refractory organic substances by NEXAFS using a compact X-ray source

Purpose  

We present the characterization of environmental samples using near-edge X-ray absorption fine structure (NEXAFS) spectra recorded with an in-house device. We want to point out the feasibility of such an easily accessed complementary technique, if not sometimes alternative to NEXAFS studies performed with synchrotron radiation, as the number of compact setups is increasing.     

Crystal tectonics: construction of reticulated calcium phosphate frameworks in bicontinuous reverse microemulsions

The chemical construction of organized architectures is an important aspect of innovative materials synthesis. Bicontinuous water-filled microemulsions can be used as preorganized systems for the fabrication of crystalline calcium phosphate materials with extended reticulated microstructures. These macroporous materials are formed by mineralization reactions located within the interconnecting water channels of the bicontinuous network. The resulting materials represent replicas of the microemulsion architecture, but the pore sizes are incommensurate, suggesting that secondary modifications in the bicontinuous microstructure occur during crystal growth. Synthetic macroporous calcium phosphates could have uses in biomaterial implants.