Management of Difficult Airway in a Cat with Tonsillitis

Background: Tracheal intubation is performed in an anesthetized patient in order to optimize oxygenation and to allow the administration of volatile anesthetics. Some patients have characteristics that make intubation a challenge. Therefore, an adequate pre-anesthetic evaluation enables the anesthesiologist to define the best management. There are reports of the impossibility of performing conventional intubation attributed to the lack of pre-anesthetic consultation in Medicine, which motivates and justifies the discussion of these aspects in Veterinary Medicine. Therefore, this study aims to report a case of difficult airway management in a feline with tonsillitis. Case: A 3-year-old male NDB cat weighing 3.5 kg was admitted to the Veterinary Hospital, Federal University of Pampa (UNIPAMPA) - Uruguaiana, for consultation. After physical examination, total tooth extraction and tonsillectomy was recommended. On the day of the procedure, a physical evaluation of the patient was performed, and he was classified as ASA II. Zolazepam and tiletamine [Zoletil®️ - 5 mg/kg, i.m] associated with morphine [Dimorf®️ - 0.3 mg/kg, i.m] was given as premedication. Given the difficulty of intubation in a previous procedure reported by the tutor, a thoughtful conduct was planned for the intubation of the patient, considering the possibility of tracheostomy. The patient was pre-oxygenated, and subsequently, propofol [Propovan®️ - 4 mg/kg, i.v] was administered to promote anesthetic induction. The first attempt at intubation was done by laryngoscopy, but despite the use of a 6 cm blade, it was too large in relation to the hyperplastic tissue; then swabs and a flashlight were subsequently used. With the help of two people, the experienced anesthesiologist was able to position the endotracheal tube correctly approximately 25 min after the first attempt, requiring supplemental doses of propofol [Propovan®️ to the effect, i.v] and oxygenation between the attempts. Anesthetic maintenance was achieved with isoflurane [Isoforine®️ vaporized in 100% oxygen] in a system without gas rebreathing. Locoregional block of the maxillary nerve and inferior branch of the mandibular nerve was performed with lidocaine 2% [0.1 mL/kg]. During the transoperative, the vital parameters remained stable and there was no need for analgesic rescue. After the end of the procedure and extubation, the patient received oxygen therapy via facemask until he regained consciousness and had no complications.Discussion: The mortality of dogs and cats related to anesthetic procedures is substantially higher when compared to humans. Studies have shown that most anesthetic-related complications in humans are predictable. The lack of adequate pre-anesthetic evaluation or anesthetic consultation are factors that can cause losses in the transoperative period. Therefore, sharing information that can mitigate these situations is critical. The scarcity of reports on pre-anesthetic evaluation in veterinary medicine allows the identification of a gap on the role of the anesthesiologist in this important stage of anesthesia, and how it is performed in the hospital routine or in veterinary clinics. The success in managing the difficult airway in the case reported here can be attributed to the procedures adopted in all stages of the procedure, especially the planning based on information obtained during the pre-anesthetic period. It is worth mentioning that the owner was a veterinarian and we believe this also contributed to the outcome, since he informed the anesthesiologist about the difficulties encountered during the previous procedure. This case motivated the implementation of a pre-anesthetic consultation service in the hospital in question. In addition to the physical examination, a complete anamnesis carried out with the owner may reveal relevant details for determining the most appropriate and safe anesthetic conduct for the patient.Keywords: preanesthetic evaluation, endotracheal intubation, veterinary anesthesia.Título: Manejo da via aérea difícil em um gato com tonsiliteDescritores: avaliação pré-anestésica, intubação endotraqueal, anestesiologia veterinária.

Pediatric Corrective Spine Surgery: “The Concerns and Essentials of Anaesthetic Management”

The perioperative management of children undergoing surgical correction of spinal deformities is challenging, even in the hands of an experienced anesthesiologist. A comprehensive plan is imperative keeping in mind that the surgery is extensive, the patients have other significant organ involvement and the need for neurophysiological monitoring to assess cord function and prevent neurological deficit. Meticulous prone positioning and the application of various blood- sparing techniques are an integral part of the intraoperative management. The pre-operative status and the intra-operative events could help in predicting the need for post-operative ventilatory support. The present article aims to elucidate the importance of a streamlined evaluation, monitoring, management strategy and stratification of these patients for a favorable outcome. Keywords: Paediatric, Spine surgery, Evoked potentials.

Anesthetic Management of the Patient with Retropharyngeal Abscess with Emphasis on Perioperative and Airway Management

Retropharyngeal abscess is a surgical emergency as well as an airway emergency. Patients with this condition must have their airway secured as soon as possible in the operating rooms where safe and efficient help is available. Calling for assistance from experienced anesthesiologists and technicians is critical for the successful conduct of the fiber-optic intubation. Ensuring that operating rooms and airway equipment are promptly prepared and having a surgeon who is ready to insert a surgical airway are also essential steps in the process. The most experienced anesthesiologist should perform the intubation under American Society of Anesthesiologists monitoring and after institution of effective topical airway anesthesia and conscious sedation if time and the condition of the patient allow. Effective collaboration between nursing, surgery, and anesthesia services are important for the effective and safe conduct of securing the airway.

Pulmonary Hypertension

Pulmonary hypertension is one of the most challenging medical conditions for even the most experienced anesthesiologist to manage. The very dynamic nature of pulmonary vascular disease lends itself to potential catastrophic changes that can increase the perioperative morbidity and mortality. Given the potential for significant hemodynamic, oxygenation, and ventilation changes during perioperative care it is imperative that the pediatric anesthesiologist not only perform a history and physical exam in this high-risk patient population but also carefully evaluate the most recent cardiac studies such as echocardiograms and catheterizations. The anesthesiologist must ensure that the patient is not overdue for cardiology exams and studies. Finally, the pediatric anesthesiologist must also communicate with the surgeon and cardiologist regarding the risk and benefit of the procedure; along with the severity of the patient’s pulmonary hypertension, in order to formulate and ultimately execute an anesthetic plan that decreases the possibility for perioperative complications.

Cadaveric Evaluation of Different Approaches for Quadratus Lumborum Blocks

Background. A quadratus lumborum (QL) block is an abdominal truncal block technique that primarily provides analgesia and anaesthesia to the abdominal wall. This cadaveric study was undertaken to compare the dye spread between different needle approaches for ultrasound-guided QL blocks in soft-embalmed cadavers. Methods. After randomization, an experienced anesthesiologist performed two lateral, three posterior, and five alternative QL blocks on the left or right sides of five cadavers. The target injection point for the alternative approach was the lumbar interfascial triangle, same as that of conventional posterior QL block, with a different needle trajectory. For each block, 20 ml of dye solution was injected. The lumbar region and abdominal flank were dissected. Results. Ten blocks were successfully performed. Regardless of the approach used, the middle thoracolumbar fascia was deeply stained in all blocks, but the anterior layer was less stained. The alternative approach was more associated with spread of injectate to the transversus abdominis and transversalis fascia plane. Despite accurate needle placement, all lateral QL blocks were associated with a certain amount of intramuscular or subcutaneous infiltration. Two posterior QL blocks showed a deeply stained posterior thoracolumbar fascia, and one of them was associated with obvious subcutaneous staining. The subcostal, iliohypogastric, and ilioinguinal nerves were mostly involved, but the thoracic paravertebral space and lumbar plexus were not affected in all blocks. Conclusions. The alternative approach for QL blocks was able to achieve a comparable extent when compared to the conventional approach.

Prolonged “Phantom” Square Wave Capnograph Tracing after Patient Disconnection or Extubation

Background The authors report on the appearance of misleading square wave "phantom" capnograph tracings for approximately 3 min after disconnection from the Siemens Servo 900c ventilator. A series of experiments are described to examine the mechanism of this phenomenon. Methods Patients were ventilated using the Siemens Servo 900c ventilator with the following settings: minute volume, 5 1/min; respiratory rate, 8 breaths/min; PEEP, 0 cm H2O; trigger sensitivity, 20 cm H2O. The ventilator was connected to the Siemens Servo Evac 180 evacuation system (25 1/min on evacuation flowmeter). Airway pressure and capnography were recorded at the Y piece during ventilation and after disconnection. A back-up ventilator was used to support the patient during disconnection of the ventilator being studied. Results Initially, the "phantom" capnograph tracing closely resembled the square wave capnograph tracing before disconnection, but the amplitude and shape of the waveform gradually decayed. Based on experiments described in this article, the authors show that the carbon dioxide for the "phantom" capnograph tracing comes from the gas exhaled by the patient in the last breaths before disconnection and which is present in both the expiratory tubing and in the evacuation system. The small pressure gradient between the exhaust reservoir and the atmosphere causes reverse flow of expired gas after disconnection, when both the nonreturn flap valve at the exhaust outlet is open (due to minimal valve incompetence) and when the expiratory servo valve is open (in the absence of positive end-expiratory pressure). This continuous reverse flow is detected by the capnograph but is interrupted intermittently by each attempted positive pressure ventilation, thereby creating a "phantom" capnograph. Conclusions After accidental disconnection of the patient from the breathing system, or after accidental extubation of the trachea, the "phantom" capnograph is likely to confuse even an experienced anesthesiologist into the mistaken belief that his rapidly deteriorating patient is being ventilated adequately. Several potential mechanisms to eliminate this phenomenon are outlined, including the avoidance of zero positive end-expiratory pressure. "Phantom" capnography provides an illustration of the dangers of using monitoring techniques, however reliable, as a substitute for vigilant clinical observation.