Traumatic Diaphragmatic Rupture Repair in a Bitch: Total Intravenous Anesthesia Protocol

Abstract

Background: Animals patients presenting with diaphragmatic rupture require emergency surgical intervention. The protrusion of abdominal viscera into the thoracic cavity, a direct consequence of diaphragmatic rupture, frequently results in significant cardiovascular and respiratory alterations. The implementation of anesthetic techniques and protocols aimed at minimizing hemodynamic impact, promoting adequate gas exchange, and ensuring analgesic comfort are crucial elements for the maintenance of homeostasis and tissue perfusion. This report aims to present and critically analyze a total intravenous anesthetic protocol, employing propofol, dexmedetomidine, and lidocaine, used during an exploratory thoracoscopy that evolved into a conventional open celiotomy due to the presence of a diaphragmatic rupture.

Case: A 7-month-old bitch of undefined breed was admitted with a history of automotive trauma that occurred 30 days prior, presenting with respiratory difficulty, apathy, and anorexia since the incident. Following initial stabilization, a loss definition of the cardiac and diaphragmatic silhouette was observed, along with a significant presence of pleural effusion. Based on the clinical and radiological findings, a diagnostic exploratory thoracoscopy was chosen, which was later converted into a pre-umbilical midline celiotomy due to the detection of a diaphragmatic rupture with hepatic herniation. The anesthetic protocol employed consisted of the continuous administration of dexmedetomidine (1 mcg/kg, followed by 1,5 mcg/kg/h) and lidocaine (2 mg/kg, followed by 3 mg/kg/h), aiming to provide effective analgesia during and immediately after the surgical procedure. Hypnotic maintenance was ensured by the continuous infusion of propofol (ranging from 250 to 100 mcg/kg/min). The adopted anesthetic protocol proved to be efficacious, providing adequate analgesia and hemodynamic stability throughout the entire procedure, without oscillations in the anesthetic plane or the need for additional analgesic intervention. The anesthetic awakening occurred quickly and smoothly, allowing for extubation 2 min after the end of the surgical procedure. Discharge from the surgical block was possible after 1 h of postoperative time, with no signs of respiratory discomfort and low pain levels.

Discussion: The continuous administration of dexmedetomidine in conjunction with lidocaine resulted in adequate intraoperative analgesia for exploratory thoracoscopy and pre-umbilical celiotomy procedures. There was no detection of nociceptive stimuli nor the need for analgesic intervention throughout the entirety of the procedure. Dexmedetomidine, possessing analgesic properties comparable to potent opioids but without inducing significant respiratory depression, contributed to this outcome. These properties are obtained through pain modulation by inhibiting the release of norepinephrine in the synaptic cleft and preventing the progression of the nerve impulse, resulting in nociceptive suppression. Intravenous lidocaine, in turn, presents multiple benefits, including anti-hyperalgesic, anti-inflammatory, and analgesic action, being considered an excellent analgesic adjuvant. Additionally, the combination of these drugs allowed a significant reduction in the need for propofol to maintain an adequate anesthetic plane, without occurrence of superficialization. Although dexmedetomidine is not yet widely recognized as a potent analgesic in clinical practice, this report evidences that its combination with analgesic adjuvants, such as lidocaine, can ensure effective analgesia, with safety and hemodynamic stability, even in high-risk surgical procedures in small animals.

Keywords: canine, analgesia, continuous infusion, video surgery, trauma, multimodal anesthesia.

Título: Reparo de ruptura traumática do diafragma em uma cadela: protocolo de anestesia intravenosa total

Descritores:  canino, analgesia, infusão contínua, videocirurgia, trauma, anestesia multimodal.