Endotracheal tube cuff rupture during anesthesia in 2 dogs.

A 15-year-old intact male dachshund dog weighing 4.3 kg and a 5-year-old intact male mixed-breed dog weighing 13.6 kg were referred for examination because of paraparesis and facial paralysis, respectively. Magnetic resonance imaging (MRI) of the thoracolumbar region and brain was performed. The dogs were premedicated with IV butorphanol, 0.2 mg/kg body weight (BW) and midazolam, 0.2 mg/kg BW. Anesthesia was induced with IV propofol, 4 to 5 mg/kg BW and maintained with sevoflurane in oxygen. The dachshund was orotracheally intubated with a 5.0-millimeter internal diameter endotracheal (ET) tube. During positioning in the MRI room, intermittent positive pressure ventilation (IPPV) was applied. The mixed-breed dog was orotracheally intubated with a 6.0-millimeter internal diameter ET tube. After inflation of the ET tube cuff, a leaking test was done by applying positive pressure ventilation. In both dogs, a distinct "popping" sound was heard when positive pressure was applied, after which air leakage from the cuff was evident. Failure to inflate the pilot balloon led to suspicion of a ruptured cuff. Reintubation was completed, both dogs remained stable during anesthesia, and no postanesthetic complications were observed. Rupture of both cuffs, which was visually confirmed, was thought to be caused by overinflation of the cuff, repeated sterilization of the ET tubes, and positive pressure ventilation. Repeated sterilization of ET tubes with ethylene oxide can alter the physical integrity of cuffs. Care should be taken not to overinflate ET tube cuffs, especially when they have been repeatedly sterilized, as cuff rupture may result in failure to provide adequate IPPV. Key clinical message: This report describes 2 cases in which ET tube cuff rupture was noted during anesthesia for MRI.

Rupture du ballonnet du tube endotrachéal pendant l'anesthésie chez 2 chiens. Un chien teckel mâle intact de 15 ans pesant 4,3 kg et un chien croisé mâle intact de 5 ans pesant 13,6 kg ont été référés pour examen en raison de paraparésie et de paralysie faciale, respectivement. Une imagerie par résonance magnétique (IRM) de la région thoraco-lombaire et du cerveau a été réalisée. Les chiens ont reçu une prémédication avec du butorphanol IV, 0,2 mg/kg de poids corporel (PC), et du midazolam, 0,2 mg/kg PC. L'anesthésie a été induite avec du propofol IV, 4 à 5 mg/kg de PC et maintenue avec du sévoflurane dans de l'oxygène. Le teckel a été intubé par voie orotrachéale avec un tube endotrachéal (TE) de diamètre interne de 5,0 millimètres. Lors du positionnement dans la salle d'IRM, une ventilation intermittente à pression positive (VIPP) a été appliquée. Le chien de race mixte a été intubé par voie orotrachéale avec un TE de 6,0 millimètres de diamètre interne. Après le gonflage du ballonnet du TE, un test d'étanchéité a été effectué en appliquant une ventilation à pression positive. Chez les deux chiens, un son distinct de « claquement ¼ a été entendu lorsqu'une pression positive a été appliquée, après quoi une fuite d'air du ballonnet est devenue évidente. Le fait de ne pas gonfler le ballon pilote a fait soupçonner une rupture du ballonnet. Une ré-intubation a été effectuée, les deux chiens sont restés stables pendant l'anesthésie et aucune complication post-anesthésique n'a été observée. La rupture des deux ballonnets, confirmée visuellement, aurait été causée par un surgonflage du ballonnet, une stérilisation répétée des TE et une ventilation à pression positive. La stérilisation répétée des TE avec de l'oxyde d'éthylène peut altérer l'intégrité physique des ballonnets. Il convient de veiller à ne pas surgonfler les ballonnets des TE, en particulier lorsqu'ils ont été stérilisés à plusieurs reprises, car la rupture du ballonnet peut entraîner l'incapacité de fournir une VIPP adéquate.Message clinique clé:Ce rapport décrit 2 cas dans lesquels une rupture du ballonnet du TE a été constatée lors d'une anesthésie pour IRM.(Traduit par Dr Serge Messier).

Polarization-Dependent Memory and Erasure in Quantum Dots/Graphene Synaptic Devices.

We demonstrate excitatory and inhibitory properties in a single heterostructure consisting of two quantum dots/graphene synaptic elements using linearly polarized monochromatic light. Perovskite quantum dots and PbS quantum dots were used to increase and decrease photocurrent weights, respectively. The polarization-dependent photocurrent was realized by adding a polarizer in the middle of the PbS quantum dots/graphene and perovskite quantum dots/graphene elements. When linearly polarized light passed through the polarizer, both the lower excitatory and upper inhibitory devices were activated, with the lower device with the stronger response dominating to increase the current weight. In contrast, the polarized light was blocked by the polarizer, and the above device was only operated, reducing the current weight. Furthermore, two orthogonal polarizations of light were used to perform the sequential processes of potentiation and habituation. By adjustment of the polarization angle of light, not only the direction of the current weight but also its level was altered.

The effects of maxillary nerve block, ethmoidal nerve block and their combination on cardiopulmonary responses to nasal stimulation in anesthetized Beagle dogs.

OBJECTIVE: To describe an approach for ethmoidal nerve block (EBLOCK) and to compare the effects of a maxillary nerve block (MBLOCK), EBLOCK and their combination (M-EBLOCK) on heart rate (HR), systolic (SAP), mean (MAP), diastolic (DAP) arterial pressures and respiratory rate (fR) during nasal stimulation in dogs. STUDY DESIGN: Prospective, blinded, randomized, crossover placebo-controlled study. ANIMALS: Beagle dogs (five cadavers, nine live dogs), with a median (interquartile range) weight of 10.5 (10.3-11.0) kg. METHODS: The accuracy of iohexol injections (each 1 mL) at the maxillary and ethmoidal foramina in cadavers was evaluated using computed tomography. Then, anesthetized dogs were administered four bilateral treatments separated by 1 week, saline or 2% lidocaine 1 mL per injection: injections of saline at the maxillary and ethmoidal foramina (Control), injections of lidocaine at the maxillary foramina and saline at the ethmoidal foramina (MBLOCK), injections of saline at the maxillary foramina and lidocaine at the ethmoidal foramina (EBLOCK) and injections of lidocaine at all foramina (M-EBLOCK). The ventral nasal meatus was bilaterally stimulated using cotton swabs, and HR, SAP, MAP, DAP and fR were continuously recorded. Values for each variable were compared before and after stimulation using Wilcoxon signed-rank test. Changes in variables among treatments were analyzed using Mann-Whitney U and Kruskal-Wallis tests (p ≤ 0.05). RESULTS: Computed tomography revealed iohexol distribution around the openings of the target foramina in all cadavers. In living dogs, HR, SAP, MAP, DAP and fR significantly increased after stimulation within each treatment (p < 0.03). Physiologic responses were significantly attenuated, but not absent, in the M-EBLOCK [HR (p = 0.019), SAP, MAP, DAP and fR (all p ≤ 0.001)] compared with those in the Control. CONCLUSIONS AND CLINICAL RELEVANCE: Concurrent injections of lidocaine at the maxillary and ethmoidal foramina attenuated HR, arterial pressure and fR responses to nasal stimulation in Beagle dogs.

Fluoroscopy-guided approach to the lumbar dorsal root ganglion in dogs: cadaver study in Beagles.

OBJECTIVE: To evaluate an approach to the canine lumbar dorsal root ganglion (DRG), a significant contributor to the pain pathway, using new methylene blue staining. STUDY DESIGN: Prospective randomized study. ANIMALS: A total of three Beagle dog cadavers weighing 10.4 ± 0.7 kg (mean ± standard deviation). METHODS: Bilateral third to fifth lumbar DRG approaches were performed in three dog cadavers positioned in sternal recumbency. The mammillary process was palpated, and a 22 gauge spinal needle was inserted through the skin 1 cm lateral to the process and directed towards the median plane at a 45° angle to the dorsal plane. The needle was advanced along the transverse plane until touching bone, or a popping sensation was detected. Under fluoroscopic guidance, the position of the needle tip was adjusted to be in the cranioventral part of the intervertebral foramen. The location of the needle was confirmed by demarcation of the nerve roots after iohexol (0.1 mL) injection. For evaluation of the DRG approach, new methylene blue (0.1 mL) was injected. Subsequently, anatomical dissection of the area was performed. The DRG staining was scored as follows: 0, no staining; 1, partial (<50%); 2, partial (≥50%); and 3, complete staining. Comparisons among the staining scores of the third to fifth DRG were assessed with the Friedman test. RESULTS: Staining score 3 was achieved in 14 of 18 (77.8%) sites. Staining scores 2, 1 and 0 were identified at two, one and one of the 18 sites, respectively. No significant difference was noted in the staining scores among the third to fifth DRGs (p = 0.78). CONCLUSIONS AND CLINICAL RELEVANCE: The technique used for DRG injections achieved adequate DRG staining, supporting use of the fluoroscopy-guided approach to the canine lumbar DRG.

Effect of intra-abdominal hypertension on plasma exogenous creatinine clearance in conscious and anesthetized dogs.

OBJECTIVE: To evaluate the effect of intra-abdominal pressure (IAP) on plasma exogenous creatinine clearance in both conscious and anesthetized dog models using a balloon technique to generate intra-abdominal hypertension. DESIGN: Prospective, cross-over, experimental study. SETTING: University-based small animal research facility. ANIMALS: Six healthy male Beagle dogs. INTERVENTIONS: A balloon device comprising a Foley urinary catheter and latex balloon was placed in the intra-abdominal cavity. Plasma exogenous creatinine clearance was compared after intravenous administration of exogenous creatinine solution at 80 mg/kg under 4 different treatment conditions as follows: control and IAP levels of 25 mm Hg in conscious dogs and control and IAP levels of 25 mm Hg in anesthetized dogs (CC, C25, AC, and A25, respectively). Samples were obtained before (T0) and 10, 20, 30, 60, 90, 120, 240, 360, 480, and 600 min after administration of creatinine in all treatment groups. MEASUREMENTS AND MAIN RESULTS: There were no significant differences in plasma creatinine concentration for CC, AC, and C25 during the treatment period. However, in the A25 treatment condition, the plasma creatinine concentration increased significantly at 10, 20, 30, 60, 90, and 120 min after administration of creatinine (P < 0.05). Plasma creatinine clearances were 5.0 ± 0.5, 4.7 ± 1.2, 5.5 ± 0.9, and 2.5 ± 0.5 mL/kg/min for 600 min (CC, AC, C25, and A25, respectively). In the A25 treatment condition, the plasma exogenous creatinine clearance decreased significantly to 50%, 47%, and 55% of that under control conditions (CC, AC, and C25, respectively). After decompression of the abdomen, plasma creatinine concentrations declined rapidly and returned to basal concentrations. CONCLUSIONS: Intra-abdominal hypertension under general anesthesia could cause renal hypoperfusion. Timely decompression may improve the outcome of acutely increased IAP when surgery and/or general anesthesia is required in canine patients.

Cranial versus caudal thoracic epidural anesthesia using three volumes of lidocaine in conscious Beagle dogs.

OBJECTIVE: To compare the effects of epidural injection of three volumes of lidocaine injected at the third (T3) or eleventh thoracic vertebra (T11) in conscious dogs to induce thoracic epidural anesthesia (TEA) and to measure the epidural dispersion of iohexol under similar conditions. STUDY DESIGN: Prospective crossover experiment. ANIMALS: A group of five Beagle dogs weighing 10.4 ± 0.5 kg (mean ± standard deviation). METHODS: Each dog was anesthetized twice, separated by 1 week, for inserting an epidural catheter at the lumbosacral space and advancing the tip to T3 (treatment TEAT3) or T11 (treatment TEAT11). For each treatment, three volumes of 2% lidocaine (0.05, 0.10 and 0.20 mL kg-1) were administered at 24 hour intervals, and sensory blockade (SB) of dermatomes was estimated by pinching the skin with mosquito forceps. Under identical conditions of injection volume and site, iohexol was administered 3 hours after lidocaine injection to identify epidural distribution (ED) using computed tomography. The effects of injection site and volume on SB of thoracic dermatomes and ED were analyzed using a linear mixed model (p < 0.05). RESULTS: Thoracic SB and ED significantly increased as the volume increased (p < 0.001 and p < 0.001, respectively), and significantly decreased in TEAT3 than in TEAT11 (p = 0.011 and p = 0.002, respectively). Cervical SB was obtained in three of five dogs in TEAT3 and two of five dogs in TEAT11 injected with 0.20 mL kg-1. One dog showed temporary inspiratory stridor probably caused by bilateral laryngeal paralysis, but no hypoxia. CONCLUSIONS AND CLINICAL RELEVANCE: TEA induced at T3 produced less thoracic SB than did TEA at T11 with the same volumes of lidocaine. The cervical SB obtained with the highest volume of lidocaine may increase the risk of laryngeal paralysis and pulmonary aspiration.

Changes in endotracheal tube intracuff pressure and air leak pressure over time in anesthetized Beagle dogs.

OBJECTIVE: To evaluate endotracheal tube intracuff pressure (Pcuff) changes over time and the effect of these changes on air leak pressure (Pleak). STUDY DESIGN: Prospective experimental study. ANIMALS: A group of nine healthy adult Beagle dogs. METHODS: In part I, in vitro measurements of Pcuff were recorded for 1 hour in eight endotracheal tubes subjected to four treatments: room temperature without lubricant (RT0L), room temperature with lubricant (RTWL), body temperature without lubricant (BT0L), and body temperature with lubricant (BTWL). In part II, nine dogs were endotracheally intubated and Pleak was evaluated at Pcuff of 25 mmHg. Subsequently, Pcuff was reset to 25 mmHg (baseline) and Pcuff measurements were recorded every 5 minutes for 1 hour. Subsequently, a second Pleak measurement was recorded at the current Pcuff. The data were analyzed using Wilcoxon signed-rank test, repeated measures anova and Mann-Whitney U test. RESULTS: In part I, Pcuff differed significantly between the RT0L and RTWL treatments at 5-60 minutes, and between the BT0L and BTWL treatments at 5-35, 55 and 60 minutes (p < 0.05). In part II, compared with baseline pressures, mean Pcuff decreased to <18 mmHg at 10 minutes and significant decreases were recorded at 15-60 minutes (Pcuff range: 10.0 ± 4.9 to 13.4 ± 6.3 mmHg, mean ± standard deviation). Significant differences were observed between the first and second Pleak measurements (p = 0.034). Pleak decreased in six of nine dogs, was not changed in two dogs and increased in one dog. CONCLUSIONS AND CLINICAL RELEVANCE: Significant decreases in Pcuff over time were measured. Pleak may decrease during anesthesia and increase the risk for silent pulmonary aspiration. The results indicate the need for testing Pcuff more than once, especially at 10 minutes after the onset of anesthesia.

A novel balloon technique to induce intra-abdominal hypertension and its effects on cardiovascular parameters in a conscious dog model.

OBJECTIVE: To evaluate a new balloon technique to induce intra-abdominal hypertension (IAH) and abdominal compartment syndrome in a conscious dog model, and to evaluate the effect of intra-abdominal pressure (IAP) on cardiovascular, respiratory, and arterial blood gas values in conscious dogs with IAH. DESIGN: Prospective, experimental study. SETTING: University-based small animal research facility. ANIMALS: Six healthy Beagle dogs, 4 males, and 2 females. INTERVENTIONS: A new balloon device designed for this study using a Foley urethral catheter and latex balloon was placed in the abdominal cavity. Consecutive measurements of IAP were made by measuring the intravesicular pressure. The abdomen was inflated with air to IAPs of 10, 15, 20, and 25 mm Hg. Heart rate, respiratory rate, systolic arterial blood pressure, and arterial blood gases were evaluated at baseline and at 15, 30, 45, 60, 120, 240, and 300 minutes after IAP increase. MEASUREMENTS AND MAIN RESULTS: The air insufflated into the intra-abdominal balloon device significantly increased the IAP and led to sustained IAH. The respiratory rate increased significantly (P < 0.05) when IAP was increased to 15, 20, and 25 mm Hg. Although heart rate, systolic arterial blood pressure, PaO2 , and PaCO2 did not show statistically significant differences between baseline and posttreatment values over time, the dogs with increased IAP showed a distended abdomen and apparent discomfort, and 4/6 (67%) vomited. After measurement of IAP, air was removed. There were no adverse effects noted after removal of the balloon device. CONCLUSION: The balloon device was successfully insufflated and led to sustained IAH in conscious dogs. This balloon technique does not require general anesthesia for instillation or removal of gas after installment. An acute IAP increase in normal conscious dogs induced discomfort, vomiting, and increased respiratory effort.

Selection of appropriate endotracheal tube size using thoracic radiography in Beagle dogs.

OBJECTIVE: To determine the optimal endotracheal tube size in Beagle dogs using thoracic radiography. STUDY DESIGN: Prospective, randomized, crossover experimental study. ANIMALS: A total of eight healthy adult Beagle dogs. METHODS: Lateral thoracic radiographs were used to measure the internal tracheal diameter at the thoracic inlet. This measurement was multiplied by 60, 70 and 80% to determine the outer diameter of the endotracheal tube for each dog. In each treatment, medetomidine (5 µg kg-1) was administered intravenously (IV) for premedication. Anesthesia was induced with alfaxalone (2 mg kg-1) IV and maintained with isoflurane. After induction of anesthesia, the resistance to passage of the endotracheal tube through the trachea was scored by a single anesthesiologist. Air leak pressures (Pleak) were measured at intracuff pressures (Pcuff) of 20 and 25 mmHg (27 and 34 cmH2O). The results were analyzed using Friedman tests and repeated measures anova. RESULTS: There were statistically significant increases in resistance as the endotracheal tube size increased (p = 0.003). When Pcuff was 20 mmHg, mean Pleak for the 60, 70 and 80% treatments were 9.7 ± 6.7, 16.2 ± 4.2 and 17.4 ± 3.9 cmH2O, respectively, but no significant differences were found. When Pcuff was 25 mmHg, mean Pleak for the 60, 70 and 80% treatments were 10.6 ± 8.5, 19.7 ± 4.9 and 20.8 ± 3.6 cmH2O, respectively, and statistically significant increases were found between treatments 60 and 70% (p = 0.011) and between treatments 60 and 80% (p = 0.020). Three dogs in the 80% treatment had bloody mucus on the endotracheal tube cuff after extubation. CONCLUSIONS AND CLINICAL RELEVANCE: Results based on resistance to insertion of the endotracheal tube and the ability to achieve an air-tight seal suggest that an appropriately sized endotracheal tube for Beagle dogs is 70% of the internal tracheal diameter measured on thoracic radiography.

Learning, memory and exploratory similarities in genetically identical cloned dogs.

Somatic cell nuclear transfer allows generation of genetically identical animals using donor cells derived from animals with particular traits. To date, few studies have investigated whether or not these cloned dogs will show identical behavior patterns. To address this question, learning, memory and exploratory patterns were examined using six cloned dogs with identical nuclear genomes. The variance of total incorrect choice number in the Y-maze test among cloned dogs was significantly lower than that of the control dogs. There was also a significant decrease in variance in the level of exploratory activity in the open fields test compared to age-matched control dogs. These results indicate that cloned dogs show similar cognitive and exploratory patterns, suggesting that these behavioral phenotypes are related to the genotypes of the individuals.