Evaluation of Lung Aeration and Respiratory System Mechanics in Obese Dogs Ventilated With Tidal Volumes Based on Ideal vs. Current Body Weight.

We describe the respiratory mechanics and lung aeration in anesthetized obese dogs ventilated with tidal volumes (VT) based on ideal (VTi) vs. current (VTc) body weight. Six dogs with body condition scores ≥ 8/9 were included. End-expiratory respiratory mechanics and end-expiratory CT-scan were obtained at baseline for each dog. Thereafter, dogs were ventilated with VT 15 ml kg-1 based on VTi and VTc, applied randomly. Respiratory mechanics and CT-scan were repeated at end-inspiration during VTi and VTc. Data analyzed with linear mixed models and reported as mean ± SD or median [range]. Statistical significance p < 0.05. The elastance of the lung, chest wall and respiratory system indexed by ideal body weight (IBW) were positively correlated with body fat percentage, whereas the functional residual capacity indexed by IBW was negatively correlated with body fat percentage. At end-expiration, aeration (%) was: hyperaeration 0.03 [0.00-3.35], normoaeration 69.7 [44.6-82.2], hypoaeration 29.3 [13.6-49.4] and nonaeration (1.06% [0.37-6.02]). Next to the diaphragm, normoaeration dropped to 12 ± 11% and hypoaeration increased to 90 ± 8%. No differences in aeration between groups were found at end-inspiration. Airway driving pressure (cm H2O) was higher (p = 0.002) during VTc (9.8 ± 0.7) compared with VTi (7.6 ± 0.4). Lung strain was higher (p = 0.014) during VTc (55 ± 21%) than VTi (38 ± 10%). The stress index was higher (p = 0.012) during VTc (SI = 1.07 [0.14]) compared with VTi (SI = 0.93 [0.18]). This study indicates that body fat percentage influences the magnitude of lung, chest wall, and total respiratory system elastance and resistance, as well as functional residual capacity. Further, these results indicate that obese dogs have extensive areas of hypoaerated lungs, especially in caudodorsal regions. Finally, lung strain and airway driving pressure, surrogates of lung deformation, are higher during VTc than during VTi, suggesting that in obese anesthetized dogs, ventilation protocols based on IBW may be advantageous.

Emotions and Dog Bites: Could Predatory Attacks Be Triggered by Emotional States?

Dog biting events pose severe public health and animal welfare concerns. They result in several consequences for both humans (including physical and psychological trauma) and the dog involved in the biting episode (abandonment, relocation to shelter and euthanasia). Although numerous epidemiological studies have analyzed the different factors influencing the occurrence of such events, to date the role of emotions in the expression of predatory attacks toward humans has been scarcely investigated. This paper focuses on the influence of emotional states on triggering predatory attacks in dogs, particularly in some breeds whose aggression causes severe consequences to human victims. We suggest that a comprehensive analysis of the dog bite phenomenon should consider the emotional state of biting dogs in order to collect reliable and realistic data about bite episodes.

Gonadectomy in Raccoons: Anesthetic and Cardiorespiratory Effects of Two Ketamine-Based Pre-Anesthetic Protocols before Sevoflurane-Sufentanil.

Nineteen raccoons were enrolled in this study. The aim was to evaluate and compare the quality of anesthesia and the cardiorespiratory effects following treatment with a ketamine-based combination with either dexmedetomidine (KD group) or midazolam (KM group) in raccoons undergoing ovariohysterectomy/orchiectomy. General anesthesia was maintained with sevoflurane in oxygen and sufentanil infusion. The time required to approach the animals was similar among groups resulting in a median of 5 min after IM injection. Animals in group KD were scored with greater myorelaxation (p < 0.01) and easier intubation (p < 0.05). Moreover 70% of them did not require other drugs for tracheal intubation unlike animals in group KM, which required propofol in 100% of cases. After intubation and connection to the breathing circuit, physiological parameters were monitored continuously and recorded every 5 min. Sevoflurane requirements were lower in group KD than KM (p = 0.005). Blood pressure was maintained within physiological ranges in both groups but with higher values in group KM (p < 0.05). Mild respiratory depression occurred during surgery and animals in group KM showed greater respiratory acidosis (p < 0.05). Recovery was smooth and uneventful in all animals. Both anesthetic protocols can be recommended for safe anesthesia in wild raccoons.

Respiratory effects of low versus high tidal volume with or without positive end-expiratory pressure in anesthetized dogs with healthy lungs.

OBJECTIVE To evaluate the impact of 2 tidal volumes (TVs) with or without positive end-expiratory pressure (PEEP) on lung mechanics, aeration, and gas exchange in healthy anesthetized dogs. ANIMALS 40 mixed-breed dogs with healthy lungs. PROCEDURES Anesthetized dogs were randomly assigned to 4 groups (n = 10/group) with different ventilatory settings: TV of 8 mL/kg and PEEP of 0 cm H2O (low TV group), TV of 8 mL/kg and PEEP of 5 cm H2O (low TV plus PEEP group), TV of 15 mL/kg and PEEP of 0 cm H2O (high TV group), or TV of 15 mL/kg and PEEP of 5 cm H2O (high TV plus PEEP group). Expired CO2 and respiratory rate were titrated on the basis of a predetermined stepwise protocol. Gas exchange, respiratory mechanics, and pulmonary aeration were evaluated by means of CT 30 minutes after starting mechanical ventilation at the assigned setting. RESULTS Partial pressures of arterial and expired CO2 were higher in the low TV and low TV plus PEEP groups than in the high TV and high TV plus PEEP groups. Peak and plateau airway pressures were higher in the PEEP group than in the other groups. Static lung compliance was higher in the high TV plus PEEP group than in the low TV group. Relative percentages of atelectatic and poorly aerated lung were lower in the high TV plus PEEP group than in the other groups. Oxygenation was similar among groups. CONCLUSIONS AND CLINICAL RELEVANCE Differences in TV and PEEP application during mechanical ventilation may affect respiratory function in anesthetized dogs with healthy lungs. Ventilation with a TV of 15 mL/kg and PEEP of 5 cm H2O significantly improved lung compliance and reduced the amount of atelectatic and poorly aerated lung.

Validation of the Italian version of the UNESP-Botucatu multidimensional composite pain scale for the assessment of postoperative pain in cats.

The study described in this paper had the goal to validate the Italian version of the UNESP-Botucatu multidimensional composite pain scale (UNESP-Botucatu MCPS) to assess postoperative pain in cats using video analysis and psycometric testing. The English version of the scale was translated into Italian. Thirty videos of the perioperative period of ovariohysterectomy surgery were analysed by 5 Italian observers with the aim to determine the pain score using the Italian version of the scale and to verify the need for analgesic treatment for each cat. Obtained scores were submitted to psycometric validity, responsiveness, and reliability tests. Of the 3 domains identified by factor analysis, the internal consistency was excellent for 'Psychomotor changes' and 'Protection of the painful area and vocal expressions of pain', while 'Physiological variables' showed moderate internal consistency. Significant changes in pain scores in response to surgery and analgesics confirmed content and construct validity. The agreement between the 'gold standard' and the blinded observers supported the criterion validity. Inter- and intra-rater reliability ranged from good to very good for all scale items. The cut-off point for rescue analgesia was > 7. The study concluded that the Italian version of the UNESP-Botucatu MCPS is a valid and reliable instrument for assessing postoperative pain in cats. The cut-off point for rescue analgesia provides an additional tool for guiding analgesic therapy.

Heart rate and blood pressure variations after transvascular patent ductus arteriosus occlusion in dogs.

The objective of the study was to retrospectively analyse the cardiovascular effects that occurs following the transvascular occlusion of patent ductus arteriosus in dogs. Sixteen anaesthesia records were included. Variables were recorded at the time of placing the arterial introducer, occlusion of the ductus, and from 5 to 60min thereafter, including, among the other, heart rate, systolic, diastolic and mean arterial blood pressure. The maximal percentage variation of the aforementioned physiological parameters within 60min of occlusion, compared with the values recorded at the introducer placing, was calculated. The time at which maximal variation occurred was also computed. Correlations between maximal percentage variation of physiological parameters and the diameter of the ductus and systolic and diastolic flow velocity through it were evaluated with linear regression analysis. Heart rate decreased after occlusion of the ductus with a mean maximal percentage variation of 41.0±14.8% after 21.2±13.7min. Mean and diastolic arterial blood pressure increased after occlusion with a mean maximal percentage variation of 30.6±18.1 and 55.4±27.1% after 19.6±12.1 and 15.7±10.8min, respectively. Mean arterial blood pressure variation had a significant and moderate inverse correlation with diastolic and systolic flow velocity through the ductus. Transvascular patent ductus arteriosus occlusion in anaesthetised dogs causes a significant reduction in heart rate and an increase in diastolic and mean blood arterial pressure within 20min of closure of the ductus.

WHICH AIRWAY PRESSURE SHOULD BE APPLIED DURING BREATH-HOLD IN DOGS UNDERGOING THORACIC COMPUTED TOMOGRAPHY?

This randomized controlled trial study aimed to identify the optimal positive pressure (PP) level that can clear atelectasis while avoiding pulmonary hyperinflation during the breath-hold technique in dogs undergoing thoracic computed tomography (CT). Sixty dogs affected by mammary tumors undergoing thoracic CT for the screening of pulmonary metastases were randomly assigned to six groups with different levels of PP during the breath-hold technique: 0 (control), 5 (PP5), 8 (PP8), 10 (PP10), 12 (PP12), and 15 (PP15) cmH2 O. The percentage of atelectatic lung region was lower in the PP10 (3.7 ± 1.1%; P = 0.002), PP12 (3.4 ± 1.3%; P = 0.0001), and PP15 (2.8 ± 0.9%; P = 0.006) groups than in the control group (5.0 ± 2.3%), and the percentage of poorly aerated lung region was lower in the PP8 (15.1 ± 2.6%; P = 0.0009), PP10 (13.0 ± 2.0 %; P = 0.002), PP12 (13.0 ± 2.2 %; P = 0.0002), and PP15 (11.1 ± 1.9%; P = 0.0002) groups than in the control group (19.8 ± 5.0). The percentage of normally aerated lung region, however, was higher in the PP10 (79.7 ± 4.1%; P = 0.005), PP12 (79.8 ± 5.1%; P = 0.0002), and PP15 (80.2 ± 4.9%; P = 0.002) groups than in the control group (73.4 ± 6.6%). A PP of 10-12 cmH2 O during the breath-hold technique should be considered to improve lung aeration during a breath-hold technique in dogs undergoing thoracic CT.

Pleurodesis with Thulium Cyber Laser versus talc poudrage: a comparative experimental study.

Sclerosing fluids to achieve pleurodesis could be hardly replaced for bed-side procedures, but other devices may be successfully applied during thoracoscopy. Thulium Cyber Laser was experimented for this purpose and compared to talc poudrage. Twenty pigs underwent operative videothoracoscopy (VATS). Ten models were subjected to double-port VATS and parietal pleura photoevaporation using Thulium Cyber Laser™ (TCL) 150 W 2010 nm on the posterior third of three ribs; the pleural surface was homogeneously treated inside the target perimeter. The remaining ten pigs underwent uniportal thoracoscopy; talc poudrage was performed using the current clinical practice dosage (1 g/18 kg) with accurate talc powder spread over the whole pleural surface. All models were followed up for 60 days. Pleurodesis firmness was graded on a three-tier scale (none-moderate-firm) and site-matching topographical expectancy was evaluated. TCL produced pleurodesis in all models: 7/10 were firm and 3/10 moderate. Talc poudrage pleurodesis was firm in 4/10 and moderate in 6/10. Pleural adhesions were found exclusively in the treated area after laser treatment, while talc created a wide spectrum of effects, most commonly anarchic jagged adhesions obliterating less than 50 % of the pleural cavity (7/10), mostly declivous. The pathologist found more aggressive inflammation (sometimes severe) in the talc group. Expected localized pleurodesis was always registered in laser group (10/10), while talc poudrage was found poorly effective if consistent pleurodesis is expected in an apico-dorsal position (2/10). Laser pleurodesis appears more homogeneous, qualitatively not inferior, and topographically more predictable than talc pleurodesis. Parietal photoevaporation seems effective and the localized pleurodesis is reproducible.

Effectiveness and predictability of pleurodesis with the Tachosil® surgical patch compared with talc poudrage: an experimental study.

OBJECTIVES: The human fibrinogen/thrombin surgical patch is proposed for videothoracoscopic pleurodesis after recurrent observation in routine clinical practice of site-specific pleuro-pulmonary adhesions. METHODS: A total of 36 experimental videothoracoscopies were performed on 18 pigs, all of which underwent a bilateral sequential procedure. The right or left side was casually approached and two 4.8 × 4.8 cm Tachosil® patches were placed over the dorsal lung surface in the highest antigravitary position through a double-port thoracoscopy. The contralateral side was subsequently entered by a single-port thoracoscopy to perform talc poudrage in accordance with current recommendations (1 g/18 kg). Thoracoscopy and autopsy were performed after 60 days to evaluate the outcome. Pleurodesis was graded on a predefined three-tier scale (none-moderate-firm); specimens were then submitted to the pathologist. The statistical analyses performed were: frequencies distribution, variables association test and hypothesis testing using binomial distribution. RESULTS: Pleurodesis was firm in 15/18 cases (P = 0.004), moderate in 2/18, and none in 1/18 cases with the sealant matrix. Talc pleurodesis was firm in 7/18 cases and moderate in 11/18. No surgical, medical, behavioural or growth disorders were recorded. There was complete correspondence between lung surface covered by the sealant patch and pleural adhesion topography (P < 0.001) and no other sites of adhesion were found at autopsy, whereas talc effect was commonly found to produce random pleural cavity obliteration, most frequently in declivous places, with inhomogeneous pleural adhesion for tissue density and rough/smooth outline (P < 0.001). The pathologist disclosed that talc creates a variable and unpredictable inflammatory background, sometimes severe, with the development of many granulomas. Fibrin sealant patch pleurodesis is caused by connective tissue irrespective of the pleural and pulmonary anatomy. CONCLUSIONS: The fibrin sealant patch is effective in producing localized pleurodesis in swine. The morphology and topography of the adhesions, 2 months after the patch placement, are consistent and more predictable than after talc poudrage. The latter causes a diffuse pleurodesis which is not predictable, with a predominantly gravitational location and produces a much more serious inflammatory response.

Pericardium matrix buttressing hinders the stapled bronchial stump healing.

BACKGROUND: Biomechanical and histological properties of stapled bronchi with and without bovine pericardial matrix plus collagen reinforcement are analyzed. MATERIALS AND METHODS: Pneumonectomy with mechanical bronchial suture was performed in the swine model. Pigs were randomly assigned to three groups: three-row staplers without reinforcement (Traditional), with reinforcement (Buttressed) and control "wild type", non-resected normal bronchus (Normal). Intraoperative test was carried for air leaks at 20/30/40 mm Hg endobronchial pressure. After 60 d, tracheobronchial specimen was harvested, stocked, and analyzed. Tensile test was performed using INSTRON 5965 loading frame machine. Maximal strain resistance value, length of elongation at rupture parameter, and stiffness coefficient (K) were evaluated. Histological analysis was performed. Sample size calculation was assessed (four per group), and the Student t-test was used to statistically evaluate differences in biomechanical variables. RESULTS: No fistula occurred. Biomechanical analysis showed that maximal strain resistance is 41.22 ± 2.11 N (Traditional), 24.53 ± 3.47 N (Buttressed), and 30.91 ± 0.29 N (Normal); elongation at rupture is 16.01 ± 1.82 mm (Traditional), 12.89 ± 0.48 mm (Buttressed), and 9.32 ± 0.11 mm (Normal). Finally, K is 2.59 ± 0.16 N/mm (Traditional), 1.91 ± 0.33 N/mm (Buttressed), and 3.32 ± 0.01 N/mm (Normal). Stumps without reinforcement proved higher resistance and length of elongation than reinforced ones. Normal bronchial tissue shows the highest stiffness coefficient. Statistical analysis produced significant values for each biomechanical feature. Group Buttressed stumps show greater thickness and a substantial inflammatory reaction with granulation tissue along the whole scar and around areas of discontinuity within the scar, not yet healed. CONCLUSIONS: Reinforcing the mechanical suture line of bronchial stump with bovine pericardial matrix plus collagen shows suboptimal biomechanical and histological characteristics compared to using the stapler alone.

Ultrasonographic findings and outcomes of dogs with suspected migrating intrathoracic grass awns: 43 cases (2010-2013).

OBJECTIVE: To describe ultrasonographic findings and outcomes for dogs with suspected migrating intrathoracic grass awns. DESIGN: Retrospective case series. ANIMALS: 43 client-owned dogs. PROCEDURES: Records for dogs with suspected migrating intrathoracic grass awns examined between 2010 and 2013 were reviewed. Ultrasonographic images and additional information such as signalment and pleural fluid analysis, radiographic, bronchoscopic, and CT findings were collected. Surgical treatments and outcomes were also reviewed. RESULTS: Transthoracic or transesophageal ultrasonography revealed grass awns in the pleural space (n = 13) or pulmonary parenchyma (10) of 23 dogs. Surgical removal of grass awns was successful on the first attempt in 21 of these 23 dogs (including 11/23 that had intraoperative ultrasonography performed to aid localization and removal of the awn). In the remaining 2 dogs, a second surgery was required. Twenty dogs with evidence of migrating intrathoracic grass awns had no foreign body identified on initial ultrasonographic evaluation and were treated medically; 16 developed draining fistulas, and awns identified ultrasonographically at follow-up visits were subsequently removed from the sublumbar region (n = 10) or thoracic wall (6). The remaining 4 dogs had no grass awn visualized. Clinical signs resolved in all dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Transthoracic, transesophageal, and intraoperative ultrasonography were useful for localization and removal of migrating intrathoracic grass awns. Ultrasonography may be considered a valuable and readily available diagnostic tool for monitoring dogs with suspected migrating intrathoracic grass awns.

Contrast-enhanced ultrasonographic findings in three dogs with lung lobe torsion.

Lung lobe torsion is rare but life-threatening condition in the dog. Thoracic radiographs and conventional ultrasonography cannot be conclusive for the diagnosis, and computed tomography is useful but is limited by cost and availability. This report describes the findings of contrast-enhanced ultrasonography in 3 dogs with lung lobe torsion. Contrast-enhanced ultrasonography showed the absence or reduction of pulmonary vascularization secondary to twisting of the lung lobe around its bronchovascular pedicle in all three dogs. Moreover, contrast-enhanced ultrasonography distinguished partial pulmonary atelectasis from a lung lobe torsion. These preliminary results suggest that contrast-enhanced ultrasonography can improve the accuracy of conventional ultrasonography for detection of pulmonary blood flow compromise in dogs with lung lobe torsion.

Long-term stability, functional competence, and safety of microencapsulated specific pathogen-free neonatal porcine Sertoli cells: a potential product for cell transplant therapy.

BACKGROUND: Porcine Sertoli cells (pSCs) have been employed for cell therapy in pre-clinical studies for several chronic/immune diseases as they deliver molecules associated with trophic and anti-inflammatory effects. To be employed for human xenografts, pSCs products need to comply with safety and stability. To fulfill such requirements, we employed a microencapsulation technology to increase pre-transplant storage stability of specific pathogen-free pSCs (SPF-pSCs) and evaluated the in vivo long-term viability and safety of grafts. METHODS: Specific pathogen free neonatal pigs underwent testis excision under sterility. pSCs were isolated, characterized by immunofluorescence (IF) and cytofluorimetric analysis (CA) and examined in terms of viability and function [namely, production of anti-müllerian hormone (AMH), inhibin B, and transforming growth factor beta-1 (TFGß-1)]. After microencapsulation in barium alginate microcapsules (Ba-MC), long-term SPF-pSCs (Ba-MCpSCs) viability and barium concentrations were evaluated at 1, 24 throughout 40 h to establish pre-transplant storage conditions. RESULTS: The purity of isolated pSCs was about 95% with negligible contaminating cells. Cultured pSCs monolayers, both prior to and after microencapsulation, maintained high function and full viability up to 24 h of storage. At 40 h post-encapsulation, pSCs viability decreased to 80%. Barium concentration in Ba-MCpSCs lagged below the normal maximum daily allowance and was stable for 4 months in mice with no evident side effects. CONCLUSIONS: Such results suggest that this protocol for the isolation and microencapsulation of pSCs is compatible with long-haul transportation and that Ba-MCpSCs could be potentially employable for xenotransplantation.

Experimental left pneumonectomy in pigs: procedure and management.

BACKGROUND: Because there is no detailed description of procedures and perioperative management of major pulmonary resections in swine, we reviewed our experience to delineate the most effective practice in performing left pneumonectomy. MATERIALS AND METHODS: Analysis of 11 consecutive left pneumonectomies. Animal data, operative reports, anesthesia records, and perioperative facts were evaluated. Follow-up information until postoperative day 60, methods of care-taking, therapy administration, and all the stabling aspects were systematically assessed. The investigation was aimed at highlighting those procedural steps or details which make the difference in optimizing the available resources (animals, instruments, and personnel). No statistical analysis was performed considering data characteristics and the descriptive nature of information. RESULTS: Surgery requires a median time of 2 h and 16 min; two operators and one anesthesiologist represent the basic team. Circulators' number depends on goals to accomplish. The most straightforward procedure requires careful dissection of the pulmonary ligament (limited view), pulmonary veins (low variability), pulmonary artery (delicate), and finally bronchus (no variability observed). The key factors for good anesthesia management have been identified: sedation by caregivers, preoxygenation before induction of general anesthesia, high respiratory rates with low tidal volume after pneumonectomy, and noninvasive ventilation after extubation. Antibiotic prophylaxis has been performed. Postoperative care must be continuous until animals are able to stand up, afterward "preventive noncurative," and always animal friendly. Ideas for minimally stressful therapy administration are helpful. CONCLUSIONS: After the delineation of this methodology, the compliance to a routine practice allowed us to reduce time, stress, and cost; quality and quantity of possible research increased.

Anaesthetic management for balloon dilation of cor triatriatum dexter in a dog.

A three-month-old female Rottweiler puppy was referred for intravascular correction of a previously identified cor triatriatum dexter. Echocardiography confirmed the presence of a hyperechoic membrane that divided the right atrium into a cranial and caudal chamber. A foramen in this membrane allowed the blood to flow from the caudal to the cranial chamber. Balloon dilation of the defect under transthoracic echocardiographic guidance was scheduled for the following day. The dog was premedicated with 0.5 µg/kg sufentanil and 0.2 mg/kg midazolam administered intravenously. General anaesthesia was induced with 2 mg/kg propofol and maintained with inhaled isoflurane in oxygen; at the same time, a constant rate infusion of 0.5 µg/kg/h sufentanil was administered by means of an infusion pump. Uneventful ventricular and supraventricular tachyarrhythmias developed during the placement of catheters and balloon dilation. At the end of procedure, when the guide wire and balloon catheter were removed, normal sinus rhythm was observed. To the authors' knowledge, no previous reports have described the anaesthetic management of a balloon dilation procedure for cor triatriatum dexter in dogs.

Noninvasive continuous positive airway pressure delivered using a pediatric helmet in dogs recovering from general anesthesia.

OBJECTIVE: To evaluate the feasibility and efficacy of noninvasive continuous positive airway pressure (CPAP) administered with a pediatric helmet in healthy dogs recovering from general anesthesia. DESIGN: Randomized, cross-over, clinical study. SETTING: University teaching hospital. ANIMALS: Fifteen healthy female, client-owned dogs recovering from general anesthesia following elective ovariohysterectomy. INTERVENTIONS: All dogs received the same standardized anesthetic protocol (acepromazine, morphine, propofol, and isoflurane in oxygen). After extubation, a pediatric helmet was placed on all dogs and connected to a venturi valve supplied with medical air. In all patients, the gas flow was set to 50 L/minute and the FiO2 to 0.21. Dogs received the following sequence of treatments, each lasting 20 minutes: 0 CPAP (pre-CPAP), CPAP of 5 cm H2 O (CPAP), and again 0 CPAP (post-CPAP). MEASUREMENTS AND MAIN RESULTS: During the entire study, the following data were collected: pressure and FiO2 inside the helmet, mean arterial pressure, respiratory rate, heart rate, sedation score (0 = awake, 10 = deep sedation), and tolerance to the helmet (0 = excellent, 4 = poor). At the end of each phase, an arterial blood sample was sampled. As compared with the pre-CPAP and the post-CPAP periods, during the CPAP period, the PaCO2 , alveolar-arterial oxygen gradient (P[A-a]O2 ), and respiratory rate significantly decreased. The PaO2 was higher at CPAP (105.6 ± 4.0 mm Hg) compared with pre-CPAP (80.6 ± 6.9 mm Hg) and post-CPAP (86.7 ± 5.8 mm Hg). Tolerance and sedation scores during the CPAP period were not different from those in the pre-CPAP and post-CPAP periods. CONCLUSIONS: Noninvasive CPAP applied through a helmet is a feasible and effective supportive technique in dogs recovering from general anesthesia.

Effects of reduction of inspired oxygen fraction or application of positive end-expiratory pressure after an alveolar recruitment maneuver on respiratory mechanics, gas exchange, and lung aeration in dogs during anesthesia and neuromuscular blockade.

OBJECTIVE: To evaluate the effectiveness of reduction of inspired oxygen fraction (Fio(2)) or application of positive end-expiratory pressure (PEEP) after an alveolar recruitment maneuver (ARM) in minimizing anesthesia-induced atelectasis in dogs. ANIMALS: 30 healthy female dogs. PROCEDURES: During anesthesia and neuromuscular blockade, dogs were mechanically ventilated under baseline conditions (tidal volume, 12 mL/kg; inspiratory-to-expiratory ratio, 1:2; Fio(2), 1; and zero end-expiratory pressure [ZEEP]). After 40 minutes, lungs were inflated (airway pressure, 40 cm H(2)O) for 20 seconds. Dogs were then exposed to baseline conditions (ZEEP100 group), baseline conditions with Fio(2) reduced to 0.4 (ZEEP40 group), or baseline conditions with PEEP at 5 cm H(2)O (PEEP100 group; 10 dogs/group). For each dog, arterial blood gas variables and respiratory system mechanics were evaluated and CT scans of the thorax were obtained before and at 5 (T5) and 30 (T30) minutes after the ARM. RESULTS: Compared with pre-ARM findings, atelectasis decreased and Pao(2):Fio(2) ratio increased at T5 in all groups. At T30, atelectasis and oxygenation returned to pre-ARM findings in the ZEEP100 group but remained similar to T5 findings in the other groups. At T5 and T30, lung static compliance in the PEEP100 group was higher than values in the other groups. CONCLUSIONS AND CLINICAL RELEVANCE: Application of airway pressure of 40 cm H(2)O for 20 seconds followed by Fio(2) reduction to 0.4 or ventilation with PEEP (5 cm H(2)O) was effective in diminishing anesthesia-induced atelectasis and maintaining lung function in dogs, compared with the effects of mechanical ventilation providing an Fio(2) of 1.

Use of the oxygen content-based index, Fshunt, as an indicator of pulmonary venous admixture at various inspired oxygen fractions in anesthetized sheep.

OBJECTIVE: To evaluate the use of the oxygen content-based index, Fshunt, as an indicator of venous admixture (Qs/Qt) at various fractions of inspired oxygen (FIO(2)s) in anesthetized sheep undergoing Flung or 2-lung ventilation. Animals-6 healthy adult female sheep. PROCEDURES: Sheep were anesthetized and administered 5 different FIO(2)s (0.21, 0.40, 0.60, 0.80, and 1.00) in random order during 2-lung mechanical ventilation. Arterial and mixed venous blood samples were obtained at each FIO(2) after a 15-minute stabilization period. Vital capacity alveolar recruitment maneuvers were performed after blood collection. The previously used FIO(2) sequence was reversed for sample collection during Flung ventilation. Blood samples were analyzed for arterial, pulmonary end-capillary, and mixed venous oxygen content and partial pressure and for hemoglobin concentration. Oxygen hemoglobin saturation, Qs/Qt, Fshunt, and oxygen tension-based indices (OTIs; including PAO(2):FIO(2), alveolar-arterial difference in partial pressure of oxygen [PAO(2) - PAO(2)], [PAO(2) - Pao(2)]:FIO(2), [PAO(2) - PAO(2)]:PAO(2), and PAO(2):PAO(2)) were calculated at each FIO(2); associations were evaluated with linear regression analysis, concordance, and correlation tests. Intermethod agreement between Qs/Qt and Fshunt was tested via Bland-Altman analysis. RESULTS: Strong and significant associations and substantial agreement were detected between Fshunt and Qs/Qt. Relationships between OTIs and Qs/Qt varied, but overall correlations were weak. Conclusions and Clinical Relevance-Whereas OTIs were generally poor indicators of Qs/Qt, Fshunt was a good indicator of Qs/Qt at various FIO(2)s, regardless of the magnitude of Qs/Qt, and could be potentially used as a surrogate for Qs/Qt measurements in healthy sheep.

Evaluation of a butorphanol, detomidine, and midazolam combination for immobilization of captive Nile lechwe antelopes (Kobus magaceros).

Field immobilization of captive antelope may be required for medical examination, blood sample collection, and animal identification. The aim of this study was to evaluate the effects of a combination of butorphanol, detomidine, and midazolam (BDM) and its partial reversibility in Nile lechwe antelope (Kobus megaceros). Nine captive lechwes, weighing 28-64 kg, were immobilized, in February 2011, with butorphanol 0.20 ± 0.05 (mean ± SD) mg/kg, detomidine 0.20 ± 0.05 mg/kg, and midazolam 0.31 ± 0.08 mg/kg administered intramuscularly (IM) with a blowpipe. Physiologic parameters and depth of anesthesia were recorded when the animals became recumbent at 19.55 ± 8.36 min after darting (T0) and after 10 (T10), 20 (T20), and 30 (T30) min. An arterial blood sample was collected at T20. At the end of the procedures, immobilization was partially reversed with atipamezole 0.25 mg/kg IM. Quality of induction, immobilization, and recovery was scored. The BDM combination induced immobilization and lateral recumbency in 13.44 ± 5.61 min. Median induction score (scored 1 [excellent] to 4 [poor]) was 1 (range 1-2). Heart rate varied 40-104 beats/min, respiratory rate 16-108 breaths/min, and rectal temperature 36.5-40.3 C. Hyperthermia was observed and rapidly treated in three animals that demonstrated insufficient immobilization after darting. Arterial blood gas analyses revealed a mean pH of 7.43 ± 0.07, partial arterial pressure of CO(2) of 44.1 ± 6.0 mmHg, partial arterial pressure of O(2) of 74.0 ± 13.5 mmHg, and an arterial O(2) saturation of 94.77 ± 3.96%. Recovery was smooth and animals were walking in 13.44 ± 7.85 min. Median recovery score (1 = excellent to 4 = poor) was 1 (range 1-2). The BDM was effective in immobilizing captive healthy lechwes with minimal cardiorespiratory changes.

Physiological effects of an open lung ventilatory strategy titrated on elastance-derived end-inspiratory transpulmonary pressure: study in a pig model*.

RATIONALE: In the presence of increased chest wall elastance, the airway pressure does not reflect the lung-distending (transpulmonary) pressure. OBJECTIVE: To compare the physiological effects of a conventional open lung approach titrated for an end-inspiratory airway opening plateau pressure (30 cm H2O) with a transpulmonary open lung approach titrated for a elastance-derived end-inspiratory plateau transpulmonary pressure (26 cm H2O), in a pig model of acute respiratory distress syndrome (HCl inhalation) and reversible chest wall mechanical impairment (chest wall and abdomen restriction). METHODS: In eight pigs, physiological parameters and computed tomography were recorded under three conditions: 1) conventional open lung approach, normal chest wall; 2) conventional open lung approach, stiff chest wall; and 3) transpulmonary open lung approach, stiff chest wall. MEASUREMENTS AND MAIN RESULTS: As compared with the normal chest wall condition, at end-expiration non aerated lung tissue weight was increased by 116 ± 68 % during the conventional open lung approach and by 28 ± 41 % during the transpulmonary open lung approach (p < .01), whereas cardiac output was decreased by 27 ± 19 % and 22 ± 14 %, respectively (p = not significant). CONCLUSION: In this model, the end-inspiratory transpulmonary open lung approach minimized the impact of chest wall stiffening on alveolar recruitment without causing hemodynamic impairment.