Case Report Hiccup-Like Response in a Dog Anesthetized...

Case ReportHiccup-Like Response in a Dog Anesthetized with Isoflurane

Enzo Vettorato and Federico Corletto

Dick White Referrals Station Farm London Road Six Mile Bottom Cambridgeshire CB8 0UH UK

Correspondence should be addressed to Enzo Vettorato ev2dwrcouk

Received 15 April 2016 Revised 23 May 2016 Accepted 1 June 2016

Academic Editor Lysimachos G Papazoglou

Copyright copy 2016 E Vettorato and F Corletto This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

An eight-year-old female intact Golden Retriever underwent magnetic resonance imaging (MRI) for investigation of urinaryand faecal incontinence Soon after induction of general anesthesia tracheal intubation and isoflurane administration hiccup-like movements were evident These hiccup-like movements did not respond to hyperventilation and increase of anesthetic Afterhaving ruled out pulmonary disease the animal was reanesthetized with a similar technique hiccup-like movements reoccurredand did not stop after discontinuation of isoflurane and commencement of a propofol infusion Eventually a nondepolarizingneuromuscular blocking agent was administered to stop the hiccup-like response and allowMRI to be performedThis case reportdescribes the pathophysiology of hiccup-like response and its management in a dog

1 Introduction

Hiccup (or hiccough) is a brief powerful inspiratory effortaccompanied by closure of the glottis [1] In cats it resultsfrom activation of a reflexwhose afferent fibres originate fromthe pharyngeal branch of the glossopharyngeal nerve [2] andthe efferent ones from the vagal motoneuron projecting tothe phrenic nerve and laryngeal intrinsicmusclesThe centralpattern generator of the hiccup reflex seems to be in thereticular formation of the brainstem [3] Hiccup can occurat any moment of the respiratory cycle including expirationbut typically follows the inspiratory peak [1]

General anesthesia is described as one of the potentialcauses of hiccup in medical literature [3ndash5] Even if the felinespecies has been extensively used to study the pathophys-iology of hiccup [2 6ndash8] no clinical reports are presentin veterinary medicine literature describing the singultusmanifestation in anesthetized animals

This report describes the hiccup-like response that wasencountered in a dog anesthetized with isoflurane

2 Case Presentation

An eight-year-old female intact Golden Retriever weighing27 kg was referred for investigation of urinary and faecalincontinence which acutely appeared following two months

of chronic vaginal discharge The latter partially respondedto antibiotic treatment After neurological consultation theanimal was scheduled formagnetic resonance imaging (MRI)of the lumbar-sacral region under general anesthesia

On preanesthetic examination the dog appeared slightlynervous but in good physical condition (ASA II) The heartrate was 90 beats per minute (bpm) respiratory rate was 15breaths per minute (brpm) pulse quality was good mucousmembranes were pink and capillary refill time was less than2 secondsThoracic and cardiac auscultation were unremark-able as were the results of hematological and biochemicalblood tests

After a mild sedation was achieved administering metha-done intramuscularly(02mg kgminus1 Synastone AudenMcken-zie Ltd UK) anesthesia was induced intravenously 30 min-utes later with fentanyl (3 120583g kgminus1 Sublimaze Janssen-CilagLtd UK) and propofol (25mg kgminus1 Rapinovet Schering-plough Animal Health UK) The trachea was intubated witha cuffed tube the cuff was inflated intubation was unremark-able Anesthesia was maintained with isoflurane (IsoFloAbbott Laboratoires UK) in 100 oxygen delivered througha circle system Monitoring consisted of capnography mea-surement of inspired and expired anesthetic gases and oxy-gen measurement of noninvasive arterial blood pressure(Datex AS3 Helsinki Finland) and esophageal stethoscope

Hindawi Publishing CorporationCase Reports in Veterinary MedicineVolume 2016 Article ID 8127496 4 pageshttpdxdoiorg10115520168127496

2 Case Reports in Veterinary Medicine

Table 1 Arterial blood gas collected taken from a dog with hiccup-like response while anesthetized with isoflurane in oxygen 100 PaCO2

arterial carbon dioxide partial pressure PE1015840CO

2

end-expiratory partial pressure of carbon dioxide PaO2

arterial oxygen partial pressureFiO2

inspiratory fraction of oxygen HCO3

minus bicarbonate Na+ sodium K+ potassium Clminus chloride

pH PaCO2

PE1015840CO2

PaO2

FiO2

HCO3

minus Na+ K+ Clminus

mmHg mmHg mmHg mmol Lminus1 mmol Lminus1 mmol Lminus1 mmol Lminus1

749 29 22 541 89 187 157 32 118

Shortly after commencement of isoflurane administra-tion a gasping breathing patternwas noted with a respiratoryrate of 40ndash50 brpm and jerk movements of the mouth andall four limbs Heart rate was 140 bpm Inadequate depthof anesthesia was considered the cause of the observedmovements thus ventilation was assistedmanually (15 brpm)and the vaporizer setting was increased from 2 to 3(oxygen 3 Lminminus1) in order to deepen the anesthetic planeFurther a bolus of fentanyl (1 120583g kgminus1) was administeredintravenously At that time end-expiratory carbon dioxidetension (PE1015840CO

2

) was 22mmHg Because the respiratorypattern did not change during the following 10 minutesand suspecting an underlying pulmonary disease MRI wascancelled while thoracic radiographs and an arterial bloodgases analysis were performed Radiographs were unremark-able and alkalemia due to primary respiratory alkalosis wasapparent in the arterial blood gases analysis results (Table 1)The dog was allowed to recover from general anesthesiaOnce the vaporizer was turned off and the breathing systemflushed with oxygen the dogrsquos breathing pattern improvedand became normal The recovery from general anesthesiawas uneventful MRI was rescheduled for the following day

On day 2 preanesthetic assessment was unremarkableand similar to that obtained the previous day Dexmedeto-midine (125 120583g kgminus1 Dexdomitor Orion Pharma Finland)and methadone (025mg kgminus1) were administered slowlyintravenously The resulting sedative effect was good withthe animal relaxed in lateral recumbency Anesthesia wasinduced with propofol (15mg kgminus1) and after intubation ofthe trachea with a cuffed tube maintained with isoflurane(vaporizer setting was 3) in 100 oxygen at the flow of3 Lminminus1 delivered through a circle system Also in thisoccasion tracheal intubation was unremarkable

As on day 1 the animal started gasping and jerking con-tinuously as soon it was connected to the breathing systemAt that point isoflurane was immediately turned off and thebreathing system flushed with pure oxygen Anesthesia wasthenmaintainedwith a constant rate infusion (CRI) of propo-fol (03mg kgminus1minminus1) after slow administration of a loadingdose (05mg kgminus1) As the animalrsquos breathing pattern didnot improve atracurium (02mg kgminus1 Tracrium InjectionGlaxoSmithKline UK) was administered intravenously andintermittent positive pressure ventilation (Penlon Nuffield200 ventilator)was started tomaintain eucapnia (PE1015840CO

2

35ndash45mmHg) Respiratory rate was set to 15 breathes perminutetidal volume was 300mL and peak inspiratory pressure was12 cmH

2

OThe rest of the anesthetic timewas uneventful butit was necessary to top up atracurium every 15ndash20 minutesbecause hiccups restarted as soon as neuromuscular functionstarted returning

An extensive invasive sacrococcygeal neoplasia wasfound on MRI The owner decided to euthanize the dog butdeclined postmortem examination

3 Discussion

In contrast to eupneic breathing hiccups combine a suddenpowerful coordinated burst of the inspiratory muscles of thethorax diaphragm neck accessory and external intercostalmuscles with an inhibition of the expiratory abdominalmuscles activemovement of the tongue toward the roof of themouth and active adduction of the glottis which occurs afterthe beginning of inspiratory flow and it is responsible for thepeculiar sound [1] Differently from sneezing and coughinghiccup is not a protective reflex In fact during coughingand sneezing a vigorous expiratory effort is produced causingexpulsion of irritants in the upper respiratory airway [9]Moreover hiccup has to be distinguished from reverse sneez-ing The latter is a mechanosensitive aspiration reflex andconsists of a paroxysmal inspiratory effort (stertor) associatedwith adduction of laryngeal cartilages The negative pleuraland tracheal pressure generated by the inspiration allowsan increase of the inspiratory inflow once the glottis opensresulting in potential aspiration of foreign material trappedin the nasopharynx [9]

The physiology of hiccup has been extensively studiedin cats [2 6ndash8] The mechanical (cotton-tipped swab) stim-ulation of the dorsal aspect of the epipharynx has beenassociated with hiccup The response to such stimulation ischaracterized by a strong inspiratory effort large peak of neg-ative inspiratory pressure (less then minus20 cmH

2

O) spasmodicactivity of the diaphragm no contraction of the abdominalmuscles and phasic inhibition of the abductor laryngealmuscle (posterior cricoarytenoid muscle) [7] In particularthe electrical stimulation of the pharyngeal branch of theglossopharyngeal nerve (PB-IX) is responsible for hiccup Onthe contrary the stimulation of the main trunk of the IXcranial nerve evokes an expiratory reflex (cough) but not aninspiratory (hiccup-like) response [2] The lower brainstemand more precisely the reticular formation seems to be thearea where the central connection of the hiccup-like reflexis located [6] Interestingly the coordinating motor patternof coughing and sneezing has been occasionally elicited byan electrical stimulation applied to area in proximity tothose generating hiccup [6] Even if PB-IX was not directlystimulated in the dog of the present report we believe thatthe breathing pattern seen can be described as a hiccup-likeresponse

A light plane of anesthesia was initially suspected to bethe reason of the abnormal breathing pattern Fentanyl was

Case Reports in Veterinary Medicine 3

administered as a respiratory depressant and manual IPPVwas started in order to increase the alveolar ventilation andtherefore the uptake of anesthetic agent Further the lungrsquosinflation activating the stretch receptors in the bronchi andbronchioles can stimulate the Hering-Breuer reflex whichshould inhibit the normal respiratory pattern and should alsoinhibit hiccup [10] According to Butt Jr et al [3] hiccuppingduring anesthesia can be managed by deepening anesthesiaand hyperventilationwith the aimof causing apnoea and theninhibition of spontaneous ventilation Moreover continuouspositive airway pressure seems to be an efficacious method tostop hiccup during anesthesia [11] However in the presenceof hiccup the decrease of arterial carbon dioxide tension(PaCO

2

) caused by IPPV can produce the opposite effectThefrequency of hiccups seems to be inversely correlated to thePaCO

2

the frequency of hiccup decreases with increasingPaCO

2

[1] and this may be the physiological explanationfor the old notion that breath-holding will stop hiccupsThis could also explain why the dog did not respond toour initial treatment which resulted in hyperventilationand respiratory alkalosis as confirmed by arterial blood gasanalysis While in children in whom the trachea was notintubated hiccupwas associatedwith a decrease in respiratoryfrequency and minute volume oxygen desaturation andrelative bradycardia hiccupping spells were characterized byhyperventilation and respiratory alkalosis if the trachea wasintubated [12]

The lack of pulmonary disease ruled out by thoracicradiographs the acute onset of hiccup following commence-ment of isoflurane administration and establishment of anormal breathing pattern as soon as the animal was dis-connected form the breathing system were the reasons forsuspecting that the hiccup was an unusual adverse reactionof the animal to the volatile anesthetic Activation of 120574-aminobutyric acid (GABA)A receptors may facilitate hiccupin humans on the contrary baclofen a GABAB-receptoragonist is one of the most effective drugs for the treatment ofintractable hiccup [13] The interaction between halogenatedanesthetics and GABA receptors is one of the possible mech-anisms of action by which volatile anesthetics depress thecentral nervous system (CNS) and produce unconsciousness[14] Isoflurane facilitates the hiccup-like reflex in cats byactivating the central and peripheral GABAA-receptors butit also suppresses it by activating central and peripheralGABAB-receptors [8] However the same study showed thatthe hiccup-like response is inhibited proportionally to thealveolar isoflurane concentration thus lending support toButtrsquos theory [3] In the case here reported hiccup did notrespond to hyperventilation and deepening of anesthesiaand for this reason a constant rate infusion of propofol wasstarted Persistence of hiccup during propofol infusion maybe explained by the fact that propofol as well as benzo-diazepines and ultrashort acting barbiturates may facilitatehiccup in humans by activating GABAA receptors [15ndash17]

Intubation with consequent stimulation of the glottisseems to be a possible cause of hiccup in humans [18]The useof supra glottis airways devices (laryngeal mask LMA) hasbeen advocated as a possible treatment for hiccup [19] evenif 74179 cases of hiccup after induction of anesthesia were

trigged by LMA insertion [20] Unfortunately a LMA wasnot available at the time Total intravenous anesthesia withoutendotracheal intubation or any other mean of securingthe airway could have potentially stopped the hiccuppingepisode however as hiccup has been associated with relax-ation of the lower oesophageal sphincter [21 22] with refluxoccurring in up to 40 of human beings with hiccup [23]this would not be a safe option

Several drugs and techniques have been considered fortreatment of hiccup in humans [3ndash5 24] Ketamine (04ndash05mg kgminus1 IV) has been reported to rapidly terminate hiccupduring anesthesia [25] and in the postoperative period [26] byacting centrally as well as at the spinal cord level [27] Even ifthe hiccup did not stop by deepening anesthesia we cannotexclude that a more profound preanesthetic sedation wouldhave helped in controlling such hiccup-response

Neuromuscular blocking (NMB) agents are probably themost reliable way to stop hiccup during anesthesia rapidlystopping diaphragmatic contractions However they cannotbe considered as specific treatment of hiccup because theydo not remove the real cause of the singultus and do notaffect the neuronal circuitry that produces it In fact when theparalysis starts to wear off the return of the diaphragmaticactivity may be associated with a new hiccup-like patternas in the case here reported Furthermore the use of NMBagents has to be judicious if inadequate plane of anesthesiaor surgical stimulation is suspected as cause of hiccup the useof NMB agents should be avoided and anesthesia should bedeepened andor analgesics should be administered prior toconsideration of neuromuscular block

4 Conclusion

Acute hiccup is a potential complication that can occurduring sedation and general anesthesia not only in humansbut also in dogs Many interventions have been proposed totreat it but the current literature does not suggest a singleeffective treatment The administration of NMB agents canbe helpful when a real cause of hiccup cannot be identifiedand inadequate anesthesia and analgesia have been ruled outas possible causes

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

References

[1] J N Davis ldquoAn experimental study of hiccuprdquoBrain vol 93 no4 pp 851ndash872 1970

[2] T Kondo H Toyooka and H Arita ldquoHiccup reflex is mediatedby pharyngeal branch of glossopharyngeal nerve in catsrdquoNeuroscience Research vol 47 no 3 pp 317ndash321 2003

[3] H R Butt Jr W Hamelberg and J Jacoby ldquoHiccup its possiblecause and treatment in anesthesiardquo Anesthesia amp Analgesia vol40 no 2 pp 181ndash185 1961

[4] J H Lewis ldquoHiccups causes and curesrdquo Journal of ClinicalGastroenterology vol 7 no 6 pp 539ndash552 1985


[5] P Kranke L H Eberhart A M Morin J Cracknell C-AGreim and N Roewer ldquoTreatment of hiccup during generalanaesthesia or sedation a qualitative systematic reviewrdquo Euro-pean Journal of Anaesthesiology vol 20 no 3 pp 239ndash2442003

[6] H Arita T Oshima I Kita and M Sakamoto ldquoGenerationof hiccup by electrical stimulation in medulla of catsrdquo Neuro-science Letters vol 175 no 1-2 pp 67ndash70 1994

[7] T Oshima M Sakamoto and H Arita ldquoHiccuplike responseelicited bymechanical stimulation of dorsal epipharynx of catsrdquoJournal of Applied Physiology vol 76 no 5 pp 1888ndash1895 1994

[8] T Oshima and S Dohi ldquoIsoflurane facilitates hiccup-like reflexthrough gamma aminobutyric acid (GABA)A- and suppressesthrough GABAB-receptors in pentobarbital-anesthetized catsrdquoAnesthesia amp Analgesia vol 98 no 2 pp 346ndash352 2004

[9] B CMcKiernan ldquoSneezing and nasal dischargerdquo in Textbook ofVeterinary Internal Medicine S J Ettinger and E C FieldmanEds pp 79ndash85 WB Saunders Philadelphia Pa USA 4thedition 1995

[10] A Baraka ldquoInhibition of hiccup by pulmonary inflationrdquoAnesthesiology vol 32 no 3 pp 271ndash273 1970

[11] C Saitto G Gristina and E V Cosmi ldquoTreatment of hiccupsby continuous positive airway pressure (CPAP) in anesthetizedsubjectsrdquo Anesthesiology vol 57 no 4 p 345 1982

[12] R T Brouillette B T Thach Y K Abu-Osba and S L WilsonldquoHiccups in infants characteristics and effects on ventilationrdquoThe Journal of Pediatrics vol 96 no 2 pp 219ndash225 1980

[13] C Guelaud T Similowski J-L Bizec J Cabane W AWhitelaw and J-P Derenne ldquoBaclofen therapy for chronichiccuprdquo European Respiratory Journal vol 8 no 2 pp 235ndash2371995

[14] K W Miller ldquoThe nature of sites of general anaesthetic actionrdquoBritish Journal of Anaesthesia vol 89 no 1 pp 17ndash31 2002

[15] M V Jones N L Harrison D B Pritchett and T G HalesldquoModulation of theGABAA receptor by propofol is independentof the 120574 subunitrdquo Journal of Pharmacology and ExperimentalTherapeutics vol 274 no 2 pp 962ndash968 1995

[16] D B Pritchett H Sontheimer B D Shivers et al ldquoImportanceof a novel GABAA receptor subunit for benzodiazepine phar-macologyrdquo Nature vol 338 no 6216 pp 582ndash585 1989

[17] R L MacDonald C J Rogers and R E Twyman ldquoBarbiturateregulation of kinetic properties of the GABA(A) receptor chan-nel of mouse spinal neurones in culturerdquo Journal of Physiologyvol 417 pp 483ndash500 1989

[18] C W Mayo ldquoHiccuprdquo The Journal of Surgery Gynecology andObstetrics vol 55 pp 700ndash708 1932

[19] A Baraka ldquoInhibition of hiccups by the laryngeal mask airwayrdquoAnaesthesia vol 59 no 9 p 926 2004

[20] J Brimacombe and C Keller ldquoInhibition of hiccups by thelaryngeal mask airway is ineffectiverdquo Anaesthesia vol 59 no11 p 1144 2004

[21] H J Skinner B Y M Ho and R P Mahajan ldquoGastro-oesophageal reflux with the laryngeal mask during day-casegynaecological laparoscopyrdquo British Journal of Anaesthesia vol80 no 5 pp 675ndash676 1998

[22] C J Roberts and N W Goodman ldquoGastro-oesophageal refluxduring elective laparoscopyrdquo Anaesthesia vol 45 no 12 pp1009ndash1011 1990

[23] R G Vanner ldquoGastro-oesophageal reflex and hiccup duringanaesthesiardquo Anaesthesia vol 48 no 1 pp 92ndash93 1993

[24] S Launois J L Bizec W A Whitelaw J Cabane and J PDerenne ldquoHiccup in adults an overviewrdquo European RespiratoryJournal vol 6 no 4 pp 563ndash575 1993

[25] M Tavakoli and G Corssen ldquoControl of hiccups by ketaminea preliminary reportrdquo Alabama Journal of Medical Sciences vol11 no 3 pp 229ndash230 1974

[26] J Teodorowicz and M Zimny ldquoThe effect of ketamine inpatients with refractory hiccups in the postoperative periodpreliminary reportrdquo Anaesthesia Resuscitation and IntensiveTherapy Journal vol 3 no 3 pp 271ndash272 1975

[27] T R Shantha ldquoKetamine for the treatment of hiccups duringand following anesthesia a preliminary reportrdquo Anesthesia ampAnalgesia vol 52 no 5 pp 822ndash824 1973

Submit your manuscripts athttpwwwhindawicom

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Case Reports in Veterinary Medicine


Table 1 Arterial blood gas collected taken from a dog with hiccup-like response while anesthetized with isoflurane in oxygen 100 PaCO2

arterial carbon dioxide partial pressure PE1015840CO

2

end-expiratory partial pressure of carbon dioxide PaO2

arterial oxygen partial pressureFiO2

inspiratory fraction of oxygen HCO3

minus bicarbonate Na+ sodium K+ potassium Clminus chloride

pH PaCO2

PE1015840CO2

PaO2

FiO2

HCO3

minus Na+ K+ Clminus

mmHg mmHg mmHg mmol Lminus1 mmol Lminus1 mmol Lminus1 mmol Lminus1

749 29 22 541 89 187 157 32 118

Shortly after commencement of isoflurane administra-tion a gasping breathing patternwas noted with a respiratoryrate of 40ndash50 brpm and jerk movements of the mouth andall four limbs Heart rate was 140 bpm Inadequate depthof anesthesia was considered the cause of the observedmovements thus ventilation was assistedmanually (15 brpm)and the vaporizer setting was increased from 2 to 3(oxygen 3 Lminminus1) in order to deepen the anesthetic planeFurther a bolus of fentanyl (1 120583g kgminus1) was administeredintravenously At that time end-expiratory carbon dioxidetension (PE1015840CO

2

) was 22mmHg Because the respiratorypattern did not change during the following 10 minutesand suspecting an underlying pulmonary disease MRI wascancelled while thoracic radiographs and an arterial bloodgases analysis were performed Radiographs were unremark-able and alkalemia due to primary respiratory alkalosis wasapparent in the arterial blood gases analysis results (Table 1)The dog was allowed to recover from general anesthesiaOnce the vaporizer was turned off and the breathing systemflushed with oxygen the dogrsquos breathing pattern improvedand became normal The recovery from general anesthesiawas uneventful MRI was rescheduled for the following day

On day 2 preanesthetic assessment was unremarkableand similar to that obtained the previous day Dexmedeto-midine (125 120583g kgminus1 Dexdomitor Orion Pharma Finland)and methadone (025mg kgminus1) were administered slowlyintravenously The resulting sedative effect was good withthe animal relaxed in lateral recumbency Anesthesia wasinduced with propofol (15mg kgminus1) and after intubation ofthe trachea with a cuffed tube maintained with isoflurane(vaporizer setting was 3) in 100 oxygen at the flow of3 Lminminus1 delivered through a circle system Also in thisoccasion tracheal intubation was unremarkable

As on day 1 the animal started gasping and jerking con-tinuously as soon it was connected to the breathing systemAt that point isoflurane was immediately turned off and thebreathing system flushed with pure oxygen Anesthesia wasthenmaintainedwith a constant rate infusion (CRI) of propo-fol (03mg kgminus1minminus1) after slow administration of a loadingdose (05mg kgminus1) As the animalrsquos breathing pattern didnot improve atracurium (02mg kgminus1 Tracrium InjectionGlaxoSmithKline UK) was administered intravenously andintermittent positive pressure ventilation (Penlon Nuffield200 ventilator)was started tomaintain eucapnia (PE1015840CO

2

35ndash45mmHg) Respiratory rate was set to 15 breathes perminutetidal volume was 300mL and peak inspiratory pressure was12 cmH

2

OThe rest of the anesthetic timewas uneventful butit was necessary to top up atracurium every 15ndash20 minutesbecause hiccups restarted as soon as neuromuscular functionstarted returning

An extensive invasive sacrococcygeal neoplasia wasfound on MRI The owner decided to euthanize the dog butdeclined postmortem examination

3 Discussion

In contrast to eupneic breathing hiccups combine a suddenpowerful coordinated burst of the inspiratory muscles of thethorax diaphragm neck accessory and external intercostalmuscles with an inhibition of the expiratory abdominalmuscles activemovement of the tongue toward the roof of themouth and active adduction of the glottis which occurs afterthe beginning of inspiratory flow and it is responsible for thepeculiar sound [1] Differently from sneezing and coughinghiccup is not a protective reflex In fact during coughingand sneezing a vigorous expiratory effort is produced causingexpulsion of irritants in the upper respiratory airway [9]Moreover hiccup has to be distinguished from reverse sneez-ing The latter is a mechanosensitive aspiration reflex andconsists of a paroxysmal inspiratory effort (stertor) associatedwith adduction of laryngeal cartilages The negative pleuraland tracheal pressure generated by the inspiration allowsan increase of the inspiratory inflow once the glottis opensresulting in potential aspiration of foreign material trappedin the nasopharynx [9]

The physiology of hiccup has been extensively studiedin cats [2 6ndash8] The mechanical (cotton-tipped swab) stim-ulation of the dorsal aspect of the epipharynx has beenassociated with hiccup The response to such stimulation ischaracterized by a strong inspiratory effort large peak of neg-ative inspiratory pressure (less then minus20 cmH

2

O) spasmodicactivity of the diaphragm no contraction of the abdominalmuscles and phasic inhibition of the abductor laryngealmuscle (posterior cricoarytenoid muscle) [7] In particularthe electrical stimulation of the pharyngeal branch of theglossopharyngeal nerve (PB-IX) is responsible for hiccup Onthe contrary the stimulation of the main trunk of the IXcranial nerve evokes an expiratory reflex (cough) but not aninspiratory (hiccup-like) response [2] The lower brainstemand more precisely the reticular formation seems to be thearea where the central connection of the hiccup-like reflexis located [6] Interestingly the coordinating motor patternof coughing and sneezing has been occasionally elicited byan electrical stimulation applied to area in proximity tothose generating hiccup [6] Even if PB-IX was not directlystimulated in the dog of the present report we believe thatthe breathing pattern seen can be described as a hiccup-likeresponse

A light plane of anesthesia was initially suspected to bethe reason of the abnormal breathing pattern Fentanyl was



2


2


2







4 Conclusion


Competing Interests


References




































Microbiology


AnimalsJournal of








Volume 2014



Agronomy







Volume 2014

Zoology



InsectsJournal of




VirusesJournal of








2


2


2







4 Conclusion


Competing Interests


References




































Microbiology


AnimalsJournal of








Volume 2014



Agronomy







Volume 2014

Zoology



InsectsJournal of




VirusesJournal of





































Microbiology


AnimalsJournal of








Volume 2014



Agronomy







Volume 2014

Zoology



InsectsJournal of




VirusesJournal of






Case Report Hiccup-Like Response in a Dog Anesthetized...

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