Ventral recumbency is crucial for fast and safe orotracheal intubation in laboratory swine

Abstract

The aim of this study was to find the fastest, easiest and safest method of achieving orotracheal intubation for general anaesthesia in laboratory pigs. Twenty-one Yorkshire  Landrace crossbreed male castrated pigs (32.9 + 4.8 kg) were investigated. Dorsal and ventral recumbency are the alternatives most frequently described for animal positioning during intubation procedures. Based on standardized induction of general anaesthesia using pentobarbital and remifentanil, the dorsoventral and ventrodorsal positions were compared with regard to the time needed, changes in oxygenation and circulatory response. Positioning was found to be crucial for fast orotracheal intubation. The time required for safe intubation is significantly shorter with the ventrodorsal position (17.3 s) in comparison with the dorsoventral position (58.4 s; P , 0.001). Hypoxia did not occur in either group. A significant drop in systolic blood pressure was observed in both groups. Diastolic and mean arterial pressures were not influenced by intubation. A significant increase in heart rate was observed in pigs intubated in ventral recumbency, but not after intubation in the dorsal position. Preoxygenation before intubation is vitally important for preventing hypoxia. With regard to clinical practice, the haemodynamic changes observed in this investigation do not appear to be relevant, as the mean arterial pressure was not altered and heart rates only increased moderately. It may be concluded that the ventrodorsal position can be recommended for orotracheal intubation in pigs as the first choice for providing a smooth and fast airway.

Animal Models Reflecting Chronic Obstructive Pulmonary Disease and Related Respiratory Disorders: Translating Pre-Clinical Data into Clinical Relevance

“…Large pigs (100-115 kg) have organ-to-body weight ratios similar to those of humans and very similar lung structures to humans, with only primate lungs showing more similarities [292]. The major downfall of the experimental pig model is the exceptionally narrow mouth opening, making intubation and intratracheal procedures very challenging, often requiring the use of modified human equipment [293,294]. Furthermore, extensive housing requirements increase the cost of using pigs in respiratory studies [295].…”

The Use of a Plastic Guide Improves the Safety and Reduces the Duration of Endotracheal Intubation in the Pig

“…[10] in pigs intubated in ventral recumbency. However, their experiments were performed on relatively small pigs (32.9 ± 4.8 kg).…”

“…After catheterization of the auricular vein using a 22 G cannula (Vasofix Certo, B.Braun, Melsungen, Germany), anesthesia was induced by an intravenous bolus injection of either sodium thiopental 2–4 mg/kg (Thiopental 1,000 mg, Sandoz, International GmbH, Holzkirchen, Germany) or propofol 1–2 mg/kg (Propofol 1% MTC/LCT Fresenius Kabi AG, Bad Homburg, Germany). Thirty pigs were endotracheally intubated by the standard orotracheal method [8, 10] using a laryngoscope whose blade length was 195 mm. The dimensions of the endotracheal tube (Sumi, Sulejowek, Poland) were 5.0–8.5 mm (internal diameter) and 26–28 cm (length), and the size of endotracheal tube that was used to intubate each pig was selected according to the body weight of the animal.…”

“…In order to advance the tube, the tube is twisted using a corkscrew action. After passing the tube through the cricoid cartilage, the tube is rotated through an angle of 180 degree and this rotation advances the tube beyond the ventral floor of the larynx and into the trachea [10]. If the pig is not intubated at first attempt, repeated attempts to endotracheally intubate become more difficult, because pigs are very susceptible to laryngospasm and edema of larynx mucosa [5], and moreover, laryngeal perforation during the standard intubation can occur [9].…”

Appraisal of the porcine kidney autotransplantation model

“…These comprise a long soft palate, pharyngeal diverticulum, angular, caudoventrally positioned, slit-like vocal cords, and sigmoidal laryngeal passage. 35 Furthermore, high susceptibility for laryngospasms and hypoxia makes careful preoxygenation prior to intubation crucial. 35 Maintenance M a i n t e n a n c e o f a n e s t h e s i a b y i n h a l a t i o n a n d / o r I V a n e s t h e t i c s v i a t h e e a r v e i n or central venous catheter potentially exerts side eff ects during prolonged exposure.…”