Effects of unilateral superimposed high-frequency jet ventilation on porcine hemodynamics and gas exchange during one-lung flooding.

BACKGROUND: Superimposed high-frequency jet ventilation (SHFJV) is suitable for respiratory motion reduction and essential for effective lung tumor ablation. Fluid filling of the target lung wing one-lung flooding (OLF) is necessary for therapeutic ultrasound applications. However, whether unilateral SHFJV allows adequate hemodynamics and gas exchange is unclear. AIM: To compared SHFJV with pressure-controlled ventilation (PCV) during OLF by assessing hemodynamics and gas exchange in different animal positions. METHODS: SHFJV or PCV was used alternatingly to ventilate the non-flooded lungs of the 12 anesthetized pigs during OLF. The animal positions were changed from left lateral position to supine position (SP) to right lateral position (RLP) every 30 min. In each position, ventilation was maintained for 15 min in both modalities. Hemodynamic variables and arterial blood gas levels were repeatedly measured. RESULTS: Unilateral SHFJV led to lower carbon dioxide removal than PCV without abnormally elevated carbon dioxide levels. SHFJV slightly decreased oxygenation in SP and RLP compared with PCV; the lowest values of PaO2 and PaO2/FiO2 ratio were found in SP [13.0; interquartile range (IQR): 12.6-5.6 and 32.5 (IQR: 31.5-38.9) kPa]. Conversely, during SHFJV, the shunt fraction was higher in all animal positions (highest in the RLP: 0.30). CONCLUSION: In porcine model, unilateral SHFJV may provide adequate ventilation in different animal positions during OLF. Lower oxygenation and CO2 removal rates compared to PCV did not lead to hypoxia or hypercapnia. SHFJV can be safely used for lung tumor ablation to minimize ventilation-induced lung motion.

Effects of one-lung flooding on porcine haemodynamics and gas exchange.

Background and aim: We established a porcine model of one-lung flooding (OLF) that can be used for research on the use of ultrasound for lung tumour detection, ultrasound-guided transthoracic needle biopsy, and tumour ablation. However, OLF requires one-lung ventilation (OLV) and eliminates the recruitment strategies of the nonventilated lung. During thoracic surgery, OLV alone can be associated with hypoxia, hypercapnia, and right ventricular overload. Here, we examined whether OLF influences haemodynamics and gas exchange indices during and after OLV/OLF compared with OLV/apnoea and two-lung ventilation (TLV) following deflooding. Methods: Fourteen pigs were included in this study: five were allocated to the control group (CO) and nine were assigned to the OLF group (OLF). Assessments of haemodynamics, gas exchange, and lung sonography were performed after baseline measurements, during OLV/apnoea, OLV/OLF, and after deflooding and TLV. The volume of extravascular lung water was also measured. Results: OLF induced no significant deterioration of oxygenation or ventilation during OLF or after deflooding and TLV. Color-coded duplex sonography of the pulmonary artery in the flooded lung demonstrated an oscillating flow that corresponded to intrapulmonary circulatory arrest. After flooding of the nonventilated lung, the partial pressure of O2 in the arterial blood increased and the shunt fraction decreased significantly compared to OLV/apnoea conditions. After deflooding and TLV, haemodynamics and gas exchange indices showed no differences compared to the CO group and baseline values, respectively. Conclusions: OLF is safe to use during acute animal experimentation. No clinically relevant deterioration of haemodynamics or gas exchange occurred during or after OLF. Due to the circulatory arrest in the flooded lung, the right-to-left shunt volume in the nonventilated lung was minimized. Survival experiments are necessary to further assess the utility of this method.

A special double lumen tube for use in pigs is suitable for different lung ventilation conditions.

Previous studies of haemodynamic and blood gas variables during one-lung ventilation in pigs have used a double lumen tube designed for use in humans. However, because of interspecies differences in bronchial anatomy, a special design for pigs is required. In this study, we evaluated a new left-sided double lumen endobronchial tube designed for use in pigs under different lung ventilation conditions. Ten female pigs (weighing 35-40 kg) were transorally intubated, first with a single lumen tube and then with the left-sided double lumen tube for pigs, and mechanically ventilated. Haemodynamic and blood gas variables were recorded before and after intubation with the double lumen tube and before and after one-lung flooding of the left lung with saline solution. Each pig was repositioned (left lateral, to dorsal, to right lateral) every 30 min during one-lung flooding. Bronchoscopy and thoracic radiography were performed at fixed intervals. Blood gas variables during two-lung ventilation were not impaired by intubation with the double lumen endobronchial tube for pigs, compared with intubation with the single lumen tube. Haemodynamic and blood gas variables were not impaired by one-lung flooding. Complete flooding of the left lung was achieved for all pigs. Two-lung ventilation to reventilate the previously flooded lung provided complete air filling for all pigs. Use of this tube resulted in lung separation without obstruction of bronchi or resultant atelectasis. In this study, the new double lumen tube for pigs was safe for one-lung flooding and prevented fluid entry into the non-flooded lung.

In Vivo Assessment of Lung Ultrasound Features Mimicking Viral Pneumonia Using a Large Animal Model.

Lung ultrasound (LUS) is a practical tool for lung diagnosis when computer tomography (CT) is not available. Recent findings suggest that LUS diagnosis is highly advantageous because of its mobility and correlation with radiological findings for viral pneumonia. Simple models for both educational evaluation and technical evaluation are needed. Therefore, this work investigates the usability of a large animal model under aspects of LUS features of viral pneumonia using saline one lung flooding. Six pigs were intubated with a double-lumen tube, and the left lung was instilled with saline. During the instillation of up to 12.5 ml/kg, the sonographic features were assessed. All features present during viral pneumonia were found, such as B-lines, white lung syndrome, pleural thickening, and the formation of pleural consolidations. Sonographic findings correlate well with current LUS scores for COVID19. The scores of 1, 2, and 3 were dominantly present at 1-4-, 4-8-, and 8-12-ml/kg saline instillation, respectively. The noninfective animal model can be used for further investigation of the LUS features and can serve in education, by helping with the appropriate handling of LUS in clinical practice during management of viral pneumonia.

[Evaluation of nutritional characteristics of commercial canned cat diets]. / Ernährungsphysiologische Beurteilung kommerzieller Feucht-Alleinfuttermittel für Katzen.

OBJECTIVE: To evaluate commercial complete canned cat foods according to their composition, labeling and nutritional characteristics. MATERIALS AND METHODS: A total of 21 commercial complete canned compound feeds for adult cats were analyzed for crude nutrients, minerals, vitamins, selected amino acids and taurine. The analyzed parameters were compared to the internal set of standards of the European Pet Food Industry Federation (FEDIAF). The energy content was calculated and compared with the labeled recommendations regarding the amounts of diet that should be fed. Analyzed nutrients were compared with the labeled nutrients according to the regulations of the EU food and feed law (directive EU regulation 767/2009). RESULTS: In many cases, the labeled feeding protocols did not match the calculated daily energy requirements. In eight complete foods, the recommended daily feed amounts were underestimated and four recommendations exceeded energy requirements of adult cats. In 12 complete foods, the calcium and phosphorus contents were threefold higher than the respective requirement. In 16 of 21 complete foods, substantial discrepancies were observed between the recommendations and the analyzed trace elements. In particular, selenium contents exceeded the selenium requirement more than threefold. The vitamin, arginine and taurine contents showed no significant discrepancies to the recommendations. With respect to the labeled nutrients, there were only minor deviations from the regulations of the European law. CONCLUSION AND CLINICAL RELEVANCE: In general, healthy adult cats are adequately supplied with energy and nutrients when feeding commercial canned complete diets for cats. In cases of body weight loss or gain, the labelled feed amounts should be questioned. The high phosphorus contents are an issue of concern, because a high phosphorus intake can potentially increase the risk for urinary stones and particularly for older cats the risk for renal insufficiency. Furthermore, it is recommended to decrease the high selenium levels by the reduction of selenium-rich feed materials such as offal.