Thoracoscopic detection of thoracic ducts after ultrasound-guided intrahepatic injection of indocyanine green detected by near-infrared fluorescence and methylene blue in dogs.

OBJECTIVE: To describe and compare onset and intensity of thoracic duct (TD) coloration in healthy dogs after intrahepatic injection of either indocyanine green (ICG) visualized by intraoperative near-infrared fluorescence lymphography (NIRFL) or direct thoracoscopic visualization of methylene blue dye (MB). STUDY DESIGN: Prospective study. ANIMALS: Healthy adult Beagle dogs (n = 5). METHODS: All dogs had biochemical panels and complete blood counts preoperatively. Computed tomography lymphography (CTL) was performed prior to a standard 3-port thoracoscopic approach. A mixture of MB and ICG was injected by ultrasound-guided percutaneous injection into right or left-sided hepatic lobes. Data collected included dose of contrast agent (MB vs. ICG), injection site, timing, and quality of operative TD identification. Potential hepatic injury was assessed by repeat laboratory evaluation and abdominal ultrasound 14 days postoperatively. RESULTS: Preoperative CTL provided a diagnostic study in 5/5 dogs. After intrahepatic injection of combined dyes, NIRFL allowed visualization of TDs in 5/5 dogs, but MB did not result in visible TD coloration in any dog. Intrahepatic injection of ICG achieved successful NIRFL in a median time of 6 minutes and persisted for the 20 minute observation period in all five dogs. All dogs recovered without complication and were subsequently adopted. CONCLUSION: NIRFL of the TD can be achieved with intraoperative hepatic injection of ICG. Intrahepatic injection of MB did not result in visible TD coloration. CLINICAL SIGNIFICANCE: Hepatic intra-parenchymal injection is a reliable alternative portal into the TD system for intraoperative visualization of TD anatomy using ICG in dogs.

Cadaveric evaluation of fluoroscopy-assisted placement of one-lung ventilation devices for video-assisted thoracoscopic surgery in dogs.

OBJECTIVE: To evaluate the feasibility of fluoroscopy-assisted placement of one-lung ventilation (OLV) devices in dogs. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Canine cadavers (n = 8) weighing between 20.2 and 37.4 kg. METHODS: Thoracoscopic access with a two-port approach was established to evaluate bilateral lung ventilation patterns. Advancement of a left-sided Robertshaw double-lumen endobronchial tube (DLT) and the EZ-blocker (EZ) were evaluated under direct fluoroscopic guidance. Each dog also underwent bronchoscopy-assisted placement of an Arndt endobronchial blocker (EBB). Time to initial placement, success of creating complete OLV (after initial placement attempt and after up to two repositionings), and ease of placement score were recorded. Device position was evaluated bronchoscopically after each fluoroscopy-assisted placement attempt. RESULTS: Time to initial placement was significantly shorter for EZ than for DLT and EBB. The rate of successful placement after up to two repositioning attempts was 87.5%, 87.5%, and 100.0% on the right and 87.5%, 100.0%, 100.0% on the left for DLT, EZ, and EBB, respectively, and was not different between devices. Ease of placement scores were significantly higher for DLT compared with EZ and EBB on both the left and the right sides. CONCLUSION: Fluoroscopy-assisted placement of DLT and EZ appears feasible in canine cadavers. EZ-blocker placement was efficient and technically easier than DLT, but positioning must be adapted for dogs. Bronchoscopy-assisted placement of EBB remains highly successful. CLINICAL SIGNIFICANCE: Fluoroscopy-assisted placement of EZ and DLT is a useful alternative to bronchoscopy-assisted placement of these OLV devices.

Successful use of ultrasound guided pecto-intercostal fascial plane block to provide intraoperative analgesia in four dogs undergoing median sternotomy.

OBJECTIVE: To evaluate the impact of pecto-intercostal fascial plane block on providing intraoperative analgesia in dogs undergoing median sternotomy. ANIMALS: 4 dogs. CLINICAL PRESENTATION: The dogs were presented with a history of inappetence, lethargy and respiratory distress. Thoracic radiographs, point of care ultrasound, thoracocentesis, bronchoscopy and computed tomography was performed to characterize the disease. RESULTS: 4 male castrated, 5.3 ± 3 years old dogs weighing 19.7 ± 13.5 kg and belonging to Dalmatian, Beagle, Siberian Husky and Rottweiler breeds were included. Three dogs were diagnosed with suppurative pleural effusions because of pulmonary abscesses and one dog with spontaneous pneumothorax due to the presence of pulmonary bullae. All dogs underwent median sternotomy under general anesthesia to explore the thorax. A pecto-intercostal fascial plane block was performed by injecting local anesthetic bupivacaine in the parasternal fascial plane between the deep pectoral and external intercostal muscles to provide antinociception by anesthetizing ventral cutaneous branches of intercostal nerves second through sixth. Analgesia from the block resulted in reduced requirement of inhalant anesthesia and minimal requirement for opioid to augment analgesia intraoperatively. CLINICAL RELEVANCE: Median sternotomy is required to perform thoracic surgery in dogs with various thoracic pathologies. Pecto-intercostal fascial plane block is a locoregional technique that can blunt nociception arising from the ventral thorax and can significantly improve perioperative patient care in dogs undergoing median sternotomy by providing effective intraoperative and potentially postoperative analgesia.

Effects of 6% hetastarch (600/0.75) or lactated Ringer's solution on hemostatic variables and clinical bleeding in healthy dogs anesthetized for orthopedic surgery.

OBJECTIVE: To evaluate and compare hemostatic variables and clinical bleeding following the administration of 6% hetastarch (600/0.75) or lactated Ringer's solution (LRS) to dogs anesthetized for orthopedic surgery. STUDY DESIGN: Randomized blinded prospective study. ANIMALS: Fourteen, healthy adult mixed-breed hound dogs of either sex, aged 11-13 months, and weighing 20.8±1.2 kg. METHODS: The dogs were randomly assigned to receive a 10 mL kg(-1) intravenous (i.v.) bolus of either 6% hetastarch (600/0.75) or LRS over 20 minutes followed by a maintenance infusion of LRS (10 mL kg(-1)  hour(-1)) during anesthesia. Before (Baseline) and at 1 and 24 hours after bolus administration, packed cell volume (PCV), total protein concentration (TP), prothrombin time (PT), activated partial thromboplastin time (APTT), von Willebrand's factor antigen concentration (vWF:Ag), factor VIII coagulant activity (F VIII:C), platelet count, platelet aggregation, colloid osmotic pressure (COP) and buccal mucosal bleeding time (BMBT) were measured. In addition a surgeon who was blinded to the treatments assessed bleeding from the incision site during the procedure and at 1 and 24 hours after the bolus administration. RESULTS: Following hetastarch or LRS administration, the PCV and TP decreased significantly 1-hour post-infusion. APTT did not change significantly compared to baseline in either treatment group, but the PT was significantly longer at 1-hour post-infusion than at 24 hours in both groups. No significant change was detected for vWF:Ag, FVIII:C, platelet aggregation or clinical bleeding in either group. The BMBT increased while platelet count decreased significantly at 1-hour post-infusion in both groups. The COP decreased significantly in both treatment groups 1-hour post-infusion but was significantly higher 1-hour post-infusion in the hetastarch group compared to the LRS group. CONCLUSIONS AND CLINICAL RELEVANCE: At the doses administered, both hetastarch and LRS can alter hemostatic variables in healthy dogs. However, in these dogs undergoing orthopedic surgery, neither fluid was associated with increased clinical bleeding.

Comparison of the efficacy and duration of desensitization of oral structures following injection of a lidocaine-bupivacaine mixture via lateral percutaneous and modified infraorbital approaches in dogs.

OBJECTIVE: To compare efficacy and duration of desensitization of oral structures with a lidocaine-bupivacaine mixture administered via a lateral percutaneous or modified infraorbital approach. ANIMALS: 6 healthy adult hound-type female dogs. PROCEDURES: In this crossover study, dogs were randomized for side (left or right) and maxillary nerve approach (lateral percutaneous or infraorbital), with a 2-week washout period. Dogs were anesthetized, and a 2-mL mixture of 2% lidocaine and 0.5% bupivacaine (50:50 [vol/vol]) was administered with a 22-gauge, 4.5-cm-long catheter inserted through the infraorbital canal (infraorbital approach) or with a shielded stimulating needle to the maxillary nerve (percutaneous approach). Reflex-evoked motor potentials were measured for the maxillary canine tooth, fourth premolar tooth, second molar tooth, and hard palate mucosa ipsilateral to the injected mixture and for the contralateral maxillary canine tooth (control) at three 10-minute intervals before injection (baseline) and at predetermined times after injection for up to 6.7 hours. For each oral structure, the proportion of dogs with desensitization (efficacy) and time to onset and duration of desensitization were compared between approaches. RESULTS: The proportion of dogs with successful nerve blockade did not significantly differ between infraorbital and percutaneous approaches and among the 4 oral structures. Time to onset of desensitization did not differ between approaches, but duration was significantly longer with the infraorbital approach. CONCLUSIONS AND CLINICAL RELEVANCE: A modified infraorbital approach with the lidocaine-bupivacaine mixture had similar effects to a lateral percutaneous approach but provided a longer duration of desensitization. Neither approach was universally successful at desensitizing all oral structures.

Comparison of the efficacy and duration of desensitization of oral structures following injection of various volumes of a lidocaine-bupivacaine mixture via an infraorbital approach in dogs.

OBJECTIVE: To compare the efficacy and duration of desensitization of oral structures following injection of various volumes of lidocaine-bupivacaine via an infraorbital approach in dogs. ANIMALS: 6 healthy adult hound-type dogs. PROCEDURES: In a randomized crossover study, each dog received 1, 2, and 3 mL of a 2% lidocaine-0.5% bupivacaine mixture (50:50 vol/vol) injected within and near the caudal aspect of the infraorbital canal with a 14-day washout period between treatments. Dogs were anesthetized, and each treatment was administered through a 22-gauge, 4.5-cm-long catheter, which was fully inserted through and then withdrawn 2 cm to the caudal aspect of the infraorbital canal. The reflex-evoked motor potential was measured for the maxillary canine tooth (MC), fourth premolar tooth (MPM4), second molar tooth (MM2), and hard palate mucosa ipsilateral to the injected treatment and for the contralateral MC (control) at predetermined times before and for 6 hours after treatment administration or until the block was no longer effective. For each oral structure, the proportion of dogs with desensitization (efficacy) and time to onset and duration of desensitization were compared among the 3 treatments (injectate volumes). RESULTS: Treatment was not associated with efficacy, time to onset, or duration of desensitization. Regardless of treatment, MC and MPM4 were more frequently desensitized and mean durations of desensitization for MC and MPM4 were longer, compared with those for MM2 and the hard palate. CONCLUSIONS AND CLINICAL RELEVANCE: The volume of local anesthetic used for an infraorbital nerve block had no effect on block efficacy or duration.

Intracranial pressure and cardiopulmonary variables during isoflurane or sevoflurane anesthesia at various minimum alveolar concentration multiples in normocapnic dogs.

OBJECTIVE: To compare effects of isoflurane and sevoflurane on intracranial pressure and cardiovascular variables at 1.0, 1.5, and 2.0 times the minimum alveolar concentration (MAC) in mechanically ventilated normocapnic dogs. ANIMALS: 6 healthy male Beagles. PROCEDURES: The individual MAC was determined for each agent with an electrical stimulus. After a minimum of 1 week, anesthetic induction by use of a mask with one of the inhalation anesthetics selected randomly was followed by mechanical ventilation and instrumentation for measurement of intracranial pressure and cardiovascular variables. Heart rate; systolic, mean, and diastolic arterial blood pressures; central venous pressure; mean pulmonary arterial pressure; pulmonary artery occlusion pressure; cardiac output; intracranial pressure (ICP); core body temperature; end-tidal inhalation anesthetic and carbon dioxide concentration; and arterial blood gas values were measured after attaining equilibrium at 1.0, 1.5, and 2.0 MAC of each inhalation anesthetic. Cardiac index, systemic vascular resistance, pulmonary vascular resistance, and cerebral perfusion pressure (CPP) were calculated. RESULTS: Mean ICP did not differ within and between anesthetics at any MAC. Compared with equipotent concentrations of isoflurane, the CPP and mean values for systolic, mean, and diastolic arterial blood pressures were increased at 2.0 MAC for sevoflurane, whereas mean values for mean and diastolic arterial blood pressures and systemic vascular resistance were increased at 1.5 MAC for sevoflurane. CONCLUSIONS AND CLINICAL RELEVANCE: Although ICP was similar in healthy normocapnic dogs, CPP was better maintained during 2.0 MAC for sevoflurane, compared with isoflurane.

Anesthetic considerations in orthopedic patients with or without trauma.

Anesthetic management of orthopedic patients could vary from normal routine management to more challenging critical management depending on the state in which the patient is presented. Multimodal pain management strategies incorporating opioids, which are the mainstay drugs for pain management, along with adjunctive drugs like local anesthetics (eg, lidocaine), dissociative anesthetics (eg, ketamine), and alpha-2 agonists (eg, dexmedetomidine), could improve overall patient comfort and help prevent establishment of chronic pain pathways. Also, use of local nerve blocks can prevent nociception right at the point of origin. Orthopedic patients with multiple organ traumas like head injuries, spinal injuries, pulmonary fat embolism, compartment syndrome, or thoracic injuries are high-risk patients in which any life-threatening organ pathology should be addressed before the patient is put under general anesthesia. Interactions of various drugs like antibiotics and neuromuscular blocking agents used in the perioperative period in orthopedic patients should warrant a careful consideration with respect to their interactions with each other and other anesthetic drugs used.