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EVALUATION OF A LARYNGEAL MASK AIRWAY AS AN ALTERNATIVE TO OROTRACHEAL INTUBATION FOR MAINTAINING AIRWAY PATENCY DURING INHALANT ANESTHESIA UNDER SPONTANEOUS VENTILATION IN CAPYBARAS ( HYDROCHOERUS HYDROCHAERIS). J Zoo Wildl Med 2021; 52:276-286. [PMID: 33827186 DOI: 10.1638/2020-0065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2020] [Indexed: 11/21/2022] Open
Abstract
Orotracheal intubation carries greater difficulty in rodents than in most domestic species. The human laryngeal mask airway (LMA) was compared with an endotracheal tube (ETtube) for maintaining airway patency in anesthetized capybaras (Hydrochoerus hydrochaeris). Six capybaras (24-52 kg) were remotely darted with intramuscular ketamine, midazolam, and acepromazine on two occasions (≥7-day intervals). After isoflurane mask induction for random placement of an ETtube or a LMA during each episode, anesthesia was maintained with isoflurane in oxygen under spontaneous ventilation for 90-120 min. Computed tomography of the pharynx and larynx was performed in two of six animals and three of six animals with the ETtube and LMA, respectively. End-tidal isoflurane [median (range)] was not significantly different between ETtube [0.6% (0.5-1.5%)] and LMA [0.6% (0.4-0.9%)]. Heart rate [67 ± 11 beats/min (ETtube) and 67 ± 18 beats/min (LMA)], mean arterial pressure [74 ± 13 mm Hg (ETtube) and 74 ± 14 mm Hg (LMA)], arterial CO2 tension [41 ± 2 mm Hg (ETtube) and 43 ± 4 mm Hg (LMA)], and arterial O2 tension [360 ± 59 mm Hg (ETtube) and 360 ± 63 mm Hg (LMA)] were not significantly different between treatment groups. Computed tomography showed gas in the esophagus with the LMA (three of three animals); the fit of the LMA to the larynx was adequate in two of three animals and fair in one of three animals. Recovery from anesthesia was uneventful. The LMA is a feasible alternative to the ETtube for maintaining airway patency during inhalant anesthesia in spontaneously breathing capybaras. However, the LMA may be dislodged during movement of the animal.
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Armstrong L, Caulkett N, Boysen S, Pearson JM, Knight CG, Windeyer MC. Assessing the Efficacy of Ventilation of Anesthetized Neonatal Calves Using a Laryngeal Mask Airway or Mask Resuscitator. Front Vet Sci 2018; 5:292. [PMID: 30519563 PMCID: PMC6259431 DOI: 10.3389/fvets.2018.00292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 11/01/2018] [Indexed: 11/13/2022] Open
Abstract
Calves that have undergone a dystocia are often hypoxic and acidemic, which can result in reduced vigor and subsequent mortality. Methods of field resuscitation of apneic newborn calves are often ineffective and therefore underutilized. This proof-of-concept study aimed to determine the efficacy of the laryngeal mask airway (LMA) as well as the current industry standard method of ventilation, the McCulloch Calf Aspirator/ Resuscitator (MMR) for positive pressure ventilation of neonatal calves. Five LMA models of various sizes were first tested in cadaver heads to assess anatomical fit. Three LMA models in two sizes each were then tested in two anesthetized calves to determine the model best suited to ventilate calves. Next, the selected LMA and the MMR were both assessed for efficacy of ventilation. Six anesthetized calves had hypoventilation induced by administering alfaxalone intravenously. Calves were ventilated for 3 min with the LMA, allowed a brief washout period, then given a second administration of alfaxalone prior to ventilation with the MMR. Serial arterial blood gas analyses were performed prior to ventilation (baseline), at 1, 2, and 3 min during ventilation, and 1 min after ventilation had ceased. Success of ventilation was assessed by monitoring partial pressure of oxygen (PaO2), partial pressure of carbon dioxide (PaCO2), bicarbonate (HCO3-), pH, L-lactate, and hemoglobin saturation (SaO2) in arterial blood. A one-way ANOVA for repeated measures with Bonferroni correction was used to assess the efficacy of ventilation of each device compared to baseline. For the LMA, PaO2, SaO2, and pH were significantly higher than baseline throughout ventilation and PaCO2 was significantly lower than baseline at 1 min of ventilation. For the MMR, PaO2 and SaO2 were significantly higher and PaCO2 and HCO3- were significantly lower than baseline for 1 to 2 min of ventilation. This proof-of-concept study showed the LMA is an effective means of ventilating neonatal calves, as was the MMR.
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Affiliation(s)
- Laura Armstrong
- Department of Production Animal Health, University of Calgary Faculty of Veterinary Medicine, Calgary, AB, Canada
| | - Nigel Caulkett
- Department of Veterinary Clinical and Diagnostic Sciences, University of Calgary Faculty of Veterinary Medicine, Calgary, AB, Canada
| | - Søren Boysen
- Department of Veterinary Clinical and Diagnostic Sciences, University of Calgary Faculty of Veterinary Medicine, Calgary, AB, Canada
| | - Jennifer M Pearson
- Department of Production Animal Health, University of Calgary Faculty of Veterinary Medicine, Calgary, AB, Canada
| | - Cameron G Knight
- Department of Veterinary Clinical and Diagnostic Sciences, University of Calgary Faculty of Veterinary Medicine, Calgary, AB, Canada
| | - M Claire Windeyer
- Department of Production Animal Health, University of Calgary Faculty of Veterinary Medicine, Calgary, AB, Canada
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Vieitez V, Ezquerra LJ, López Rámis V, Santella M, Álvarez Gómez de Segura I. Retrograde intubation in a dog with severe temporomandibular joint ankylosis: case report. BMC Vet Res 2018; 14:118. [PMID: 29587754 PMCID: PMC5872398 DOI: 10.1186/s12917-018-1439-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 03/21/2018] [Indexed: 11/26/2022] Open
Abstract
Background Orotracheal intubation in dogs is a common and easily-performed procedure that provides a patent airway during anaesthesia. In dogs with temporomandibular joint ankylosis or pseudo-ankylosis, airway management can be a challenging procedure since these dogs have a limited ability to open their mouth. Methods to provide safe, uneventful intubation in such patients may include minimally invasive techniques such as retrograde intubation using a guide wire and fibre-optic-aided laryngoscopy. Case presentation We report a case of a 16-month-old, intact female Bull Terrier weighing 17 kg, admitted to the hospital for surgical treatment of bilateral ankylosis of the temporomandibular joint. Intubation was achieved, without direct observation of the larynx, by retrograde intubation using a vascular access catheter and a vascular wire guide through cricothyroid membrane. Bilateral condylectomy was performed and the dog recovered uneventfully. Conclusions In conclusion, retrograde intubation was relatively simple to perform with the guide wire technique and no specific training or equipment were necessary.
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Affiliation(s)
- Verónica Vieitez
- Veterinary Teaching Hospital, University of Extremadura, Avda, Universidad s/n, 10003, Cáceres, Spain.
| | - Luis Javier Ezquerra
- Veterinary Teaching Hospital, University of Extremadura, Avda, Universidad s/n, 10003, Cáceres, Spain
| | - Víctor López Rámis
- Veterinary Teaching Hospital, University of Extremadura, Avda, Universidad s/n, 10003, Cáceres, Spain
| | - Massimo Santella
- Veterinary Teaching Hospital, University of Extremadura, Avda, Universidad s/n, 10003, Cáceres, Spain
| | - Ignacio Álvarez Gómez de Segura
- Department of Animal Medicine and Surgery, Veterinary Faculty, University Complutense of Madrid, Avda. Puerta de Hierro, 28040, Madrid, Spain
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Comparison of laryngeal mask airway use with endotracheal intubation during anesthesia of western lowland gorillas (Gorilla gorilla gorilla). J Zoo Wildl Med 2013; 43:759-67. [PMID: 23272342 DOI: 10.1638/2011-0081r.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The laryngeal mask airway is an alternative to endotracheal intubation that achieves control of the airway by creating a seal around the larynx with an inflatable cuff. This study compared use of the laryngeal mask airway with endotracheal intubation in anesthetized western lowland gorillas (Gorilla gorilla gorilla). Eight adult gorillas were immobilized for routine and diagnostic purposes for a total of nine anesthetic events. During each anesthetic event, gorillas were either intubated (n = 4; group A) or fitted with a laryngeal mask airway (n= 5; group B). Time required to place each airway device, physiologic parameters, and arterial blood gas were measured and compared between the two groups. There were no significant differences between the two groups for time required to place airway device, heart rate, hemoglobin oxygen saturation, end-tidal carbon dioxide, arterial partial pressure of carbon dioxide, or arterial pH between the two groups. Mean arterial partial pressure of oxygen was significantly greater in group B, 15 (group A: 94 +/- 44 mm Hg; group B: 408 +/- 36 mm Hg; P= 0.0025) and 45 (group A: 104 +/- 21 mm Hg; group B: 407 +/- 77 mm Hg; P = 0.0026) min after airway device placement. Mean respiratory rate was significantly greater in group A at multiple time points. Mean arterial pressure (group A: 129 +/- 16 mm Hg; group B: 60 +/- 8 mm Hg) and diastolic blood pressure (group A: 115 +/- 21 mm Hg; group B: 36 +/- 10 mm Hg) were significantly greater in group A at the time of airway device placement. The laryngeal mask airway maintained oxygenation and ventilation effectively in all gorillas and is a useful alternative to endotracheal intubation in western lowland gorillas.
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Application of the Laryngeal Mask Airway for Anesthesia in Three Chimpanzees and One Gibbon. J Zoo Wildl Med 2010; 41:535-7. [DOI: 10.1638/2009-0120.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Hirt RA, Wiederstein I, Denner EBM, Mosing M, de Arespacochaga AG, Spergser J, van den Hoven R. Influence of the collection and oxygenation method on quantitative bacterial composition in bronchoalveolar lavage fluid samples from healthy dogs. Vet J 2009; 184:77-82. [PMID: 19213582 DOI: 10.1016/j.tvjl.2009.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 12/15/2008] [Accepted: 01/03/2009] [Indexed: 10/21/2022]
Abstract
The purpose of the study was to evaluate the effects on quantitative and qualitative microbial content of endoscopic bronchoalveolar lavage fluid (BALF) in healthy dogs using a laryngeal mask airway (LMA). It was hypothesised that oropharyngeal protection might prevent contamination of BALF with oropharyngeal microflora. Ten healthy Beagle dogs were randomly assigned to two groups and underwent endoscopic BAL on two occasions, either via an open unprotected oropharynx with oxygen supply provided via a nasal catheter (NT) or through a sterile LMA. For the second sampling, groups were switched. BALF analysis included quantitative microbial culture, nucleated cell counts and cytology. The mean (+/-SD) number of colony forming units (CFU)/mL found in the BALF using the LMA was 25,610+/-22,943 in the right lung (RL) and 22,510+/-18,779 in the left (LL). With the NT technique, the figures were 21,068+/-19,375 for the RL and 16,060+/-15,523 for the LL, respectively. Nucleated cell counts/microL were 691.0+/-181.6 (RL) and 734.0+/-171.6 (LL) for LMA, and 772.0+/-251.0 (RL) and 748+/-163.2 (LL) for NT. No significant differences were detected either in the number of CFU/mL or in the diversity of bacterial species with the two methods. A significant increase in BALF bacterial counts (with reduced species diversity) was observed on the second compared to the first sampling regardless of the method used. Protection of the oral cavity and oropharynx using an LMA had no significant influence on BALF bacterial counts. The findings suggest that with careful endoscope insertion, the risk of contamination of BALF by resident and transient oropharyngeal microflora can be negligible.
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Affiliation(s)
- Reinhard A Hirt
- Department for Small Animals and Horses, Clinic of Internal Medicine and Infectious Diseases, University of Veterinary Medicine Vienna (VUW), A-1210 Vienna, Austria.
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Wiederstein I, Moens YPS. Guidelines and criteria for the placement of laryngeal mask airways in dogs. Vet Anaesth Analg 2008; 35:374-82. [PMID: 18466166 DOI: 10.1111/j.1467-2995.2008.00398.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Iris Wiederstein
- Clinic of Anaesthesiology and Perioperative Intensive Care, Department of Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, Vienna, Austria.
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Birkholz T, Irouschek A, Kessler P, Blunk JA, Labahn D, Schmidt J. Feasibility of the laryngeal tube airway for artificial ventilation in pigs and comparison with the laryngeal mask airway. Lab Anim (NY) 2008; 37:371-9. [PMID: 18650825 DOI: 10.1038/laban0808-371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 04/23/2008] [Indexed: 11/09/2022]
Abstract
Airway management in anesthetized pigs is known to be technically demanding, and the 'gold standard' technique of endotracheal intubation is particularly difficult to master. The authors investigated the feasibility of the laryngeal tube as an alternative technique for airway management in German Landrace pigs (n = 5). They compared this method with the laryngeal mask, which is considered to be an effective yet relatively straightforward tool for porcine airway management. One after the other, investigators attempted to establish an airway in each anesthetized, artificially ventilated pig using each device. The laryngeal tube was too short to intubate the largest pig (weighing 45 kg), and it took investigators slightly longer to insert this device compared with the laryngeal mask. With the laryngeal mask, there were several incidents of gastric insufflation. Despite these complications, all investigators were able to establish a secure airway and maintain oxygenation with the laryngeal tube, and all subjectively rated both devices as easy to use.
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Affiliation(s)
- Torsten Birkholz
- Department of Anaesthesiology, University Hospital, University of Erlangen-Nuremberg, Erlangen, Germany.
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Fulkerson PJ, Gustafson SB. Use of laryngeal mask airway compared to endotracheal tube with positive-pressure ventilation in anesthetized swine. Vet Anaesth Analg 2007; 34:284-8. [PMID: 17490468 DOI: 10.1111/j.1467-2995.2006.00329.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To compare the ease of placement and ventilatory parameters of a laryngeal mask airway (LMA) with an endotracheal tube (ETT) in anesthetized swine during positive-pressure ventilation (PPV). STUDY DESIGN Prospective, randomized, experimental trial. ANIMALS Nine young domestic swine, weighing between 40 and 49 kg (mean 45.1 kg), being used for a separate terminal surgical study. METHODS The pigs were immobilized with tiletamine/zolazepam, 2.7-3.6 mg kg(-1), intramuscularly, followed by isoflurane in oxygen delivered by facemask. The lungs were mechanically ventilated through an ETT or an LMA, in random order, during the anesthetic period. Positive-pressure ventilation was adjusted to maintain end-tidal CO2 (Pe'CO2) between 35 and 45 mmHg, with peak inspiratory pressure (P(insp)) of 15-23 cmH2O. Buprenorphine, 0.3 mg intramuscularly, was given to each pig after instrumentation. Isoflurane vaporizer settings were adjusted to maintain a surgical plane of anesthesia. Respiratory rate (RR), tidal volume (V(T)), minute volume (V(E)), and Pe'CO2 were measured and recorded at 5-minute intervals. After the collection of 1 hour of data, the alternate airway was placed. Swine were given at least 30 minutes to stabilize and another hour of data were recorded. At the time of airway placement, the ease of placement was assessed based on time and the number of personnel required. Data were analyzed using paired Student's t-test or Wilcoxon signed rank test where appropriate. RESULTS Laryngeal mask airways were significantly easier to place than ETT. Values for V(T) and V(E) were not significantly different between treatments. Peak inspiratory pressures were higher in ETT-ventilated swine. CONCLUSIONS AND CLINICAL RELEVANCE An LMA may be used as an alternative to an ETT in mechanically-ventilated anesthetized swine. Use of an LMA may reduce time and personnel required for placement of an airway.
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Affiliation(s)
- Pamela J Fulkerson
- Magruder Hall, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
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Wiederstein I, Auer U, Moens Y. Laryngeal mask airway insertion requires less propofol than endotracheal intubation in dogs. Vet Anaesth Analg 2006; 33:201-6. [PMID: 16764583 DOI: 10.1111/j.1467-2995.2005.00254.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To compare the doses of propofol required for insertion of the laryngeal mask airway (LMA) with those for endotracheal intubation in sedated dogs. STUDY DESIGN Randomized prospective clinical study. Animals Sixty healthy dogs aged 0.33-8.5 (3.0 +/- 2.3, mean +/- SD) years, weighing 2.2-59.0 (23.4 +/- 13.6, mean +/- SD) kg, presented for elective surgery requiring inhalation anaesthesia. METHODS Animals were randomly assigned to receive either a LMA or an endotracheal tube. Pre-anaesthetic medication was intravenous (IV) glycopyrrolate (0.01 mg kg(-1)) medetomidine (10 microg kg(-1)) and butorphanol (0.2 mg kg(-1)). Repeated IV propofol injections (1 mg kg(-1) in 30 seconds) were given until LMA insertion or endotracheal intubation was achieved, when the presence or absence of laryngospasm, the respiratory rate (fr) and the total dose of propofol used were recorded. RESULTS The total propofol dose (mean +/- SD) required for LMA insertion (0.53 +/- 0.51 mg kg(-1)) was significantly lower than for endotracheal intubation (1.43 +/- 0.57 mg kg(-1)). The LMA could be inserted without propofol in 47% of dogs; the remainder needed a single 1 mg kg(-1) bolus (n = 30). Endotracheal intubation was possible without propofol in 3.3% of the dogs, 47% needed one bolus and 50% required two injections (n = 30). The f(r) (mean +/- SD) was 18 +/- 6 and 15 +/- 7 minute(-1) after LMA insertion and intubation, respectively. CONCLUSION AND CLINICAL RELEVANCE Laryngeal mask airway insertion requires less propofol than endotracheal intubation in sedated dogs therefore propofol-induced cardiorespiratory depression is likely to be less severe. The LMA is well tolerated and offers a less invasive means of securing the upper airway.
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Affiliation(s)
- Iris Wiederstein
- Department of Companion Animals and Horses, Clinic for Anaesthesiology and Perioperative Intensive Care, University of Veterinary Medicine Vienna, Vienna, Austria.
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Goldmann K, Kalinowski M, Kraft S. Airway management under general anaesthesia in pigs using the LMA-ProSeal™: a pilot study. Vet Anaesth Analg 2005; 32:308-13. [PMID: 16135212 DOI: 10.1111/j.1467-2995.2005.00248.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Evaluation of the LMA-ProSeal for positive pressure ventilation (PPV) in the pig. STUDY DESIGN Prospective observational study. ANIMALS Twelve German country pigs, weighing 25-62 kg. METHOD Lungs of pigs were mechanically ventilated under general anaesthesia using the LMA-ProSeal. The ease of insertion, number of attempts and total time until placement of the LMA-ProSeal and gastric tube were recorded. Bronchoscopy was performed to determine the position of the LMA-ProSeal and to detect signs of aspiration. Ventilation variables and the leak airway pressure (P(leak)) were measured. An arterial blood gas sample was taken to determine the adequacy of ventilation. RESULTS The airway was secured in all pigs within 39 +/- 19 seconds (27-51). Different sizes of LMA-ProSeal were used; up to 30 kg: size 3, up to 43 kg: size 4; and above 43 kg: size 5. In all but one animal the P-LMA and gastric tube were inserted at the first attempt. In nine animals gastric fluid was drained through the gastric tube. There was no evidence of aspiration in any animal. The mean [+/-SD (95%CI)]P(leak) was 28.8 +/- 7.5 cm H(2)O (24.06-33.60) and normal ventilation was achieved in all animals. CONCLUSIONS The results of this study indicate that the airway of pigs weighing 25-62 kg can be secured safely and reliably with the sizes 3, 4 and 5 LMA-ProSeal. CLINICAL RELEVANCE Endotracheal intubation in pigs can be difficult so there is a risk of hypoxemia in the apnoeic animal. With the LMA-ProSeal the airway can be secured rapidly, safely and reliably. Use of the Standard-LMA under PPV can be associated with gas leakage into the stomach and the subsequent risk of gastric distension and regurgitation. Both the ability to drain the stomach and the high P(leak) of the LMA-ProSeal could contribute to improved protection against aspiration under PPV.
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Affiliation(s)
- Kai Goldmann
- Department of Anaesthesia and Intensive Care Therapy, Philipps University Marburg, Marburg, Germany.
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Bateman L, Ludders JW, Gleed RD, Erb HN. Comparison between facemask and laryngeal mask airway in rabbits during isoflurane anesthesia. Vet Anaesth Analg 2005; 32:280-8. [PMID: 16135209 DOI: 10.1111/j.1467-2995.2005.00169.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine whether a laryngeal mask airway (LMA) provides a better airway than a facemask in spontaneously breathing anesthetized rabbits, and to test if it can be used for mechanically controlled ventilation. STUDY DESIGN Randomized prospective experimental trial. ANIMALS Sixteen young, healthy, specific pathogen-free Giant Flemish cross Chinchilla rabbits (10 females and 6 males) weighing 4.1 +/- 0.8 kg. METHODS Rabbits were assigned randomly to one of three treatment groups: facemask with spontaneous ventilation (FM-SV; n = 5), LMA with spontaneous ventilation (LMA-SV; n = 5), and LMA with controlled ventilation (LMA-CV; n = 6). In dorsal recumbency, and at 2.3% end-tidal isoflurane concentration, Fé isoflurane, Fi isoflurane, partial pressure of expired isoflurane (PECO(2)), partial pressure of inspired carbon dioxide (PiCO(2)), heart rate, respiratory rate, minute volume, arterial oxygen tensions (PaO(2)), arterial carbon dioxide tensions (PaCO(2)), arterial pH (pH(a)), arterial standard base excess (SBE(a)) values were measured for 120 minutes. Results Two individuals in the FM-SV group had PaCO(2) > 100 mm Hg. One rabbit in the FM-SV had PaO(2) < 80 mm Hg. All FM-SV rabbits showed signs of airway obstruction, and two were withdrawn from the study at 45 and 90 minutes, respectively, because cyanosis was observed. No signs of airway obstruction were observed in either LMA group. Four rabbits in the LMA-CV group developed gastric tympanism, one of which refluxed gastric contents after 110 minutes. There were no differences between FM-SV and LMA-SV in any variable tested. PaCO(2) and PECO(2) were decreased, while PaO(2) and minute volume were increased in the LMA-CV group compared to the LMA-SV group. CONCLUSIONS An LMA provided a better airway than a facemask during spontaneous breathing in rabbits, as the use of a facemask was associated with hypercapnia and low partial pressures of oxygen. Although an LMA can be used for intermittent positive pressure ventilation (IPPV), gastric tympanism may develop, especially at a peak inspiratory pressure of 14 cm H(2)O. CLINICAL RELEVANCE The LMA can be used in rabbits but further work is needed before it is applied routinely.
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Affiliation(s)
- Leigh Bateman
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
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Cassu RN, Luna SPL, Teixeira Neto FJ, Braz JRC, Gasparini SS, Crocci AJ. Evaluation of laryngeal mask as an alternative to endotracheal intubation in cats anesthetized under spontaneous or controlled ventilation. Vet Anaesth Analg 2004; 31:213-21. [PMID: 15268693 DOI: 10.1111/j.1467-2987.2004.00195.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To compare the cardiorespiratory effects and incidence of gastroesophageal reflux with the use of a laryngeal mask airway (LMA) or endotracheal tube (ET) in anesthetized cats during spontaneous (SV) or controlled ventilation (CV). STUDY DESIGN Prospective randomized experimental trial. ANIMALS Thirty-two adult crossbred cats, weighing 2.7 +/- 0.4 kg. METHODS The cats were sedated with intramuscular (IM) methotrimeprazine (0.5 mg kg(-1)) and buprenorphine (0.005 mg kg(-1)), followed 30 minutes later by induction of anesthesia with intravenous (IV) thiopental (12.5-20 mg kg(-1)). An ET was used in 16 cats and an LMA in the remaining 16 animals. Anesthesia was maintained with 0.5 minimum alveolar concentration (0.6%) of halothane in oxygen using a Mapleson D breathing system. Cats in both groups were further divided into two equal groups (n = 8), undergoing either SV or CV. Neuromuscular blockade with pancuronium (0.06 mg kg(-1)) was used to facilitate CV. Heart and respiratory rates, direct arterial blood pressure, capnometry (PE'CO2) and arterial blood gases were measured. Gastric reflux and possible aspiration was investigated by intragastric administration of 5 mL of radiographic contrast immediately after induction of anesthesia. Cervical and thoracic radiographs were taken at the end of anesthesia. Data were analyzed using anova followed by Student-Newman-Keuls, Kruskal-Wallis or Friedman test where appropriate. RESULTS Values for PaCO2 and PE'CO2 were higher in spontaneously breathing cats with the LMA when compared with other groups. Values of PaO2 and hemoglobin oxygen saturation did not differ between groups. Gastroesophageal reflux occurred in four of eight and two of eight cats undergoing CV with ET or LMA, respectively. There was no tracheal or pulmonary aspiration in any cases. CONCLUSIONS AND CLINICAL RELEVANCE The use of an LMA may be used as an alternative to endotracheal intubation in anesthetized cats. Although aspiration was not observed, gastric reflux may occur in mechanically ventilated animals.
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Affiliation(s)
- Renata N Cassu
- Faculty of Veterinary Medicine and Animal Science, FMVZ, Unesp, Department of Veterinary Surgery and Anaesthesiology, Botucatu, São Paulo, Brazil
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Abud TM, Braz JR, Martins RH, Gregório EA, Saldanha JC. High laryngeal mask airway pressures resulting from nitrous oxide do not increase pharyngeal mucosal injury in dogs. Can J Anaesth 2001; 48:800-6. [PMID: 11546723 DOI: 10.1007/bf03016698] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
PURPOSE During general anesthesia, nitrous oxide (N2O) diffuses rapidly into the air-filled laryngeal mask airway (LMA) cuff, increasing intracuff pressure. There is no clear correlation between LMA intracuff pressure and pressure on the pharynx. We have studied the effects of high LMA intracuff pressures secondary to N2O on the pharyngeal mucosa of dogs. METHODS Sixteen mongrel dogs were randomly allocated to two groups: G1 (intracuff volume, 30 mL; n=8) breathed a mixture of O2 (l L x min(-1)) and air (l L x min(-1)) and G2 (intracuff volume, 30 mL; n=8) a mixture of O2 (l L x min(-1)) and N2O (l L x min(-1)). Anesthesia was induced and maintained with pentobarbitone. LMA cuff pressure was measured at zero (control), 30, 60, 90 and 120 min after #4 LMA insertion. The dogs were sacrificed, and biopsy specimens from seven predetermined areas of the pharynx in contact with the LMA cuff were collected for light (LM) and scanning electron microscopic (SEM) examination by a blinded observer. RESULTS LMA intracuff pressure decreased with time in G1 (P <0.001) and increased in G2 (P <0.001). There was a significant difference between the groups (P <0.001). In both groups, the LM study showed a normal epithelium covering the pharyngeal mucosa and mild congestion in the subepithelial layer. There were no differences between the groups (P >0.10) or among the areas sampled (P >0.05). In both groups, the SEM study showed a normal pharyngeal mucosa with mild superficial desquamation. Few specimens in G1 and G2 showed more intense epithelial desquamation. CONCLUSION High LMA intracuff pressures produced by N2O do not increase pharyngeal mucosal injury in dogs.
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Affiliation(s)
- T M Abud
- Department of Anesthesiology, The School of Medicine of The University Of São Paulo (UNESP), Bottucatu, São Paulo, Brazil.
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Martins RH, Braz JR, Defaveri J, Gregório EA, Abud TM. Effect of high laryngeal mask airway intracuff pressure on the laryngopharyngeal mucosa of dogs. Laryngoscope 2000; 110:645-50. [PMID: 10764012 DOI: 10.1097/00005537-200004000-00020] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To evaluate the effect of increased of laryngeal mask airway (LMA) intracuff pressures on the laryngopharyngeal mucosa. STUDY DESIGN Animal model. METHODS Sixteen mixed-breed dogs were randomly allocated to two groups, G1 (intracuff volume, 30 mL; n = 8) and G2 (intracuff volume, 54 mL; n = 8), to produce, respectively, high or very high intracuff pressures. Anesthesia was induced and maintained with pentobarbital. Intracuff pressures were measured immediately after insertion and inflation of a No. 4 laryngeal mask airway (LMA) and 30, 60, 90, and 120 minutes thereafter. The dogs were euthanized, and biopsy specimens from eight predetermined areas of the laryngopharynx in contact with LMA cuff were collected for light microscopic (LM) and scanning electron microscopic (SEM) examination. RESULTS Initial LMA cuff inflation in G1 and G2 resulted in intracuff pressures of 119 mm Hg +/- 4 mm Hg and 235 mm Hg +/- 13 mm Hg, respectively. Over a 2-hour period, the intracuff pressure decreased significantly in G1 (P < .001) and G2 (P < .01), and there was a significant difference between the groups over time (P < .001). The LM study of laryngopharyngeal mucosa in both groups showed mild congestion in the subepithelial layer. There were no differences between the groups (P > .10) or among the areas sampled (P > .10). In some areas of G2, the SEM study showed epithelial desquamation that was more intense than that in G1. CONCLUSIONS The increase in LMA intracuff pressure caused only mild alterations in the laryngopharyngeal mucosa of the dog.
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Affiliation(s)
- R H Martins
- Department of Otorhinolaryngology, College of Medicine, University of São Paulo State, Botucatu, Brazil
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