Research PaperEvaluation of laryngeal mask as an alternative to endotracheal intubation in cats anesthetized under spontaneous or controlled ventilation
Introduction
Cats have small, delicate tracheae and the larynx may be easily damaged. The well‐developed protective reflexes make laryngeal spasm a common complication during or after endotracheal intubation. Consequently, intubation should be performed with particular care in this species (Rex 1994; Taylor 1994). Even when proper endotracheal tube (ET) placement is achieved, laryngeal damage during intubation may cause swelling and airway obstruction after the tube has been removed (Taylor 1994).
The laryngeal mask airway (LMA) is a relatively new device for airway management during inhalation anesthesia (Pennant & White 1993; Verghese et al. 1993; Maltby 1994; Ivens et al. 1995). It was developed in 1981 by Archie Brain and has been commercially available since 1988 (Brain 1983; Pennant & White 1993; Maltby 1994). The LMA was designed for use in human beings, but is suitable for dogs (Braz et al. 1999), pigs (Wemyss‐Holden et al. 1999), rabbits (Cruz et al. 2000) and medium and large‐sized cats (Asai et al. 1998). The LMA is a combination of the face mask and ET. It is manufactured in silicone, may be autoclaved and used several times. It is composed of a rigid tube coupled at the distal end to an oval silicone mask which forms a hermetic seal around the larynx (Maltby 1994). It has been suggested that the use of the LMA would be a safe way of providing a gas‐tight seal in the cat's airway without laryngeal damage (Steffey 1994). Asai et al. (1998) observed that the LMA was as effective as the endotracheal tube in maintaining a patent airway, suggesting that the LMA could be useful in cats and possibly in veterinary practice. The use of an LMA, however, is associated with an increased risk of gastroesophageal reflux and possible aspiration in human beings; especially when mechanical ventilation is used (Valentine et al. 1994; Bapat & Verghese 1997).
The hypothesis examined in this study was that the LMA is a practical device for airway maintenance during inhalation anesthesia in cats. Accordingly the aim of this study was to compare the cardiorespiratory effects and incidence of gastroesophageal reflux with the use of LMA or ET in cats anesthetized during either spontaneous (SV) or controlled ventilation (CV).
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Materials and methods
The study was approved by the Animal Care Committee (protocol number 22/99). Thirty‐two healthy adult crossbred cats, weighing from 2 to 3.5 kg (2.7 ± 0.4 kg) were used. Health status was assessed by physical examination and blood gas analysis performed prior to the experiment. Before the beginning of the study, the animals were maintained for 15 days in individual cages where they were treated for parasites and vaccinated. The cats were randomly distributed into four groups of eight, after
Results
There were no differences between groups in terms of mass or sex distribution (Table 1). The animals undergoing endotracheal intubation required higher doses of thiopental for laryngeal reflex suppression (17 ± 2 mg kg−1), when compared with animals undergoing LMA insertion (14 ± 1 mg kg−1).
Heart rate (HR) increased during endotracheal intubation or LMA insertion (mean ranging from 180 to 222 beats minute−1) when compared with the anesthesia maintenance phase (mean ranging from 100 to 170 beats
Discussion
A relatively low concentration of halothane (approximately 0.5 MAC) was used because, in the pilot study, a greater concentration of halothane (1 MAC) produced significant cardiopulmonary depression. This would have made it difficult to investigate the use of LMA in spontaneously breathing cats, as most of the animals developed apnea with 1 MAC. This anesthetic depression was probably related to the combination of methotrimeprazine, buprenorphine and thiopental, potentiating halothane
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Clinical evaluation of the v-gel supraglottic airway device in comparison with a classical laryngeal mask and endotracheal intubation in cats during spontaneous and controlled mechanical ventilation
2016, Veterinary Anaesthesia and AnalgesiaCitation Excerpt :One study comparing LM and ETT in cats failed to show any obvious leakage using peak inspiratory pressure up to 13 cm H2O (Cassu et al. 2004). By contrast with our study, the endotracheal cuff pressures in the study reported by Cassu et al. (2004) ranged from 60 mmHg to 100 mmHg. Inflation of the low-pressure high-volume cuff of the ETT to 20 cm H2O is known to prevent any mucosal damage of the trachea as a result of compression (Loeser et al. 1978; Seegobin & van Hasselt 1984; Joh et al. 1987), which is why we chose a cuff pressure of 20 cm H2O.
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2013, Veterinary Anaesthesia: Eleventh EditionA comparison between the v-gel supraglottic airway device and the cuffed endotracheal tube for airway management in spontaneously breathing cats during isoflurane anaesthesia
2013, Veterinary Anaesthesia and AnalgesiaCitation Excerpt :Based on these measurements, it can be concluded that the v-gel SGAD secures the airway sufficiently to prevent exposure of operating room personnel to unacceptably high concentrations of isoflurane, although it must be emphasized that all cats were breathing spontaneously in this study and that no data were obtained on isoflurane leakage during positive airway pressures, e.g. during manual or mechanical ventilation. Previous studies suggest that in several veterinary species, including cats, positive airway pressures of up to 10–23 cm H2O can be safely applied without leakage from an LMA (Cassu et al. 2004; Bateman et al. 2005; Fulkerson & Gustafson 2007; Wiederstein & Moens 2008). These studies, however, used audible measures of leakage, rather than the highly sensitive detection of volatile anaesthetic concentrations, as was done in the present study.
Veterinary Anesthesia
2011, Advances in AnesthesiaCitation Excerpt :Specialized Miller-style blades designed for pigs and ruminants, such as cattle and goats, are typically 350 to 450 mm in length. The use of laryngeal mask airways (LMAs) has been reported in dogs, cats, rabbits, pigs, and primates [9–13]. However, because of large patient size variations and the relative ease in which most of these species are intubated, LMAs are not extensively used in veterinary anesthesia.
Gastro-oesophageal reflux during anaesthesia in the kitten: Comparison between use of a laryngeal mask airway or an endotracheal tube
2009, Veterinary Anaesthesia and AnalgesiaCitation Excerpt :Contrast radiography in particular, has a low sensitivity because of its high incidence of false positive and false negative results, and the disadvantage of limitation in time (Vandenplas 1990). Furthermore, Cassu et al. (2004) performed contrast radiography after anaesthesia and a number of GOR episodes may no longer have been detectable due to the re-established oesophageal clearance mechanism. There is controversy regarding the incidence of GOR and regurgitation during anaesthesia in humans when the LMA is used.
Guidelines and criteria for the placement of laryngeal mask airways in dogs
2008, Veterinary Anaesthesia and AnalgesiaCitation Excerpt :Although primarily designed for use in humans, the LMA has also been used in veterinary anaesthesia. Experimental and clinical studies in cats (Fujita et al. 1991; Asai et al. 1998; Auer et al. 2000; Cassu et al. 2004), dogs (Kawaguchi et al. 1997; Braz et al. 1999; Wiederstein et al. 2001, 2006; Wiederstein 2002), pigs (Wemyss-Holden et al. 1999) and rabbits (Cruz et al. 2000; Bateman et al. 2005) have reported on the use of the LMA especially in spontaneously breathing animals. When considering the low airway pressures produced during spontaneous ventilation an air-tight seal is necessary to avoid anaesthetic gas leakage and/or aspiration of gastric contents.