Hooo-Hooo Volume 11 Nr 1 - Page 22

WildLife Group of the SAVA

also inhibit the actions of vagal motorneurones which promote dilation of vocal folds ( Lalley 2003 ), thereby causing an increase in upper airway resistance ( Lalley 2008 ). In addition , opioids cause catatonia ( Haveman & Kuschinsky 1982 ), which results in generalised muscle rigidity and a decrease in the chest wall compliance ( Chen et al . 1996 ). They also increase the resistance to chest wall expansion by tonically activating expiratory neurones during inspiration ( Lalley 2003 ; Lalley 2008 ).
The respiratory depressant effects of the opioids are not limited to their effects on respiratory neurones in the central neuronal network . Opioids have a direct action on carotid bodies , which causes a decrease in chemoreceptor discharge and thus further depresses the response to hypoxia and hypercapnia ( Pattinson 2008 ; Santiago & Edelman 1985 ). Opioids also activate pulmonary J receptors which may cause opioid-induced apnoea ( Bowdle 1998 ; McKenzie 1993 ; Santiago & Edelman 1985 ; Shook et al . 1990 ). The combination of all these effects will lead to a decrease in respiratory pump action and cause hypoventilation with its associated pathophysiological effects . The effects of the opioids , on both the central and peripheral neurones , therefore play a major role in decreasing pulmonary ventilation . However , the respiratory depressant effects of the opioids are not limited to just the effects on ventilation ; opioids also have marked effects on the cardiovascular system that may cause a decrease in the perfusion both of the lungs and other organs thus decreasing oxygen delivery to tissues .
The effects of opioids on the cardiovascular system are complex and dependent on the opioid and dose used ( Bowdle 1998 ). However , the opioids used during chemical immobilization of wildlife generally cause systemic and pulmonary vasoconstriction ( Haigh 1990 ; Heard et al . 1990 ; Heard et al . 1996 ; Santiago & Edelman 1985 ) by either activating the sympathetic nervous system ( Hannon & Bossone 1991 ; Heard et al . 1990 ; Heard et al . 1996 ; Roquebert & Delgoulet 1988 ) or possibly by causing the release of histamine ( Hakim et al . 1992 ; Mather 1994 ). These vascular effects would result in a decrease in blood perfusion of body tissues , and would cause ventilation perfusion mismatching or shunting of blood in the lungs , and a decrease in oxygen diffusion across the alveolar membrane ( Nunn 1993 ). Few studies have assessed pulmonary blood shunting and oxygen diffusion during opioid immobilization of animals . Two of the studies that have done so , have shown that opioid immobilization causes a decrease in oxygen diffusion in immobilized rhinoceros ( Wenger et al . 2007 ) and elephant ( Still et al . 1996 ).
Although much is known about the neurological control of respiration , and the effects of opioids on this control , a better and more integrative understanding of the effects of the opioids on cardio-respiratory control and function is needed , especially if more effective treatments for opioidinduced respiratory depression are to be established , particularly during chemical immobilization .
References Ballanyi K , Lalley PM , Hoch B , Richter DW . 1997 . cAMPdependent reversal of opioid- and prostaglandin-mediated depression of the isolated respiratory network in newborn rats . J . Physiol . 504 : 127-134 . Bowdle TA . 1988 . Clinical pharmacology of antagonists of narcotic-induced respiratory depression . A brief review . Acute Care 12 : 70-76 . Bowdle TA . 1998 . Adverse effects of opioid agonists and agonist-antagonists in anaesthesia . Drug Safety 19 : 173-189 . Chen S , Maguire PA , Davies MF , Beatty MF , Loew GH . 1996 . Evidence for μ1-opioid receptor involvement in fentanylmediated respiratory depression . Eur . J . Pharmacol . 312 : 241-244 . Haigh JJ . 1990 . Opioids in zoological medicine . J . Zoo Wildl . Med . 21 : 391-413 . Haji A , Takeda R , Okazaki M . 2000 . Neuropharmacology of control of respiratory rhythm and pattern in mature mammals . Pharmacol . Therapeut . 86 : 277-304 . Hakim TS , Grunstein MM , Michel RP . 1992 . Opiate action in the pulmonary circulation . Pulm . Pharmacol . 5 : 159-165 . Hannon JP , Bossone CA . 1991 . Cardiovascular and pulmonary effects of morphine in conscious pigs . Am . J . Physiol . Reg .
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WildLife Group of the SAVA also inhibit the actions of vagal motorneurones which promote dilation of vocal folds (Lalley 2003), thereby causing an increase in upper airway resistance (Lalley 2008). In addition, opioids cause catatonia (Haveman & Kuschinsky 1982), which results in generalised muscle rigidity and a decrease in the chest wall compliance (Chen et al. 1996). They also increase the resistance to chest wall expansion by tonically activating expiratory neurones during inspiration (Lalley 2003; Lalley 2008). The respiratory depressant effects of the opioids are not limited to their effects on respiratory neurones in the central neuronal network. Opioids have a direct action on carotid bodies, which causes a decrease in chemoreceptor discharge and thus further depresses the response to hypoxia and hypercapnia (Pattinson 2008; Santiago & Edelman NN JK[Y[X]]H[[ۘ\HX\ܜXX^H]\H[Y Z[XY\XH BNNNX[YH NNL[XY Y[X[ NN N”][ NNL KHX[][ۈو[\BYX[XYHXܙX\H[\\]ܞH[\X[ۈ[]\H\ݙ[[][ۈ]]\X]Y]\[X[YX˂HYXوH[YۈH[[[\\\[]\ۙ\\YܙH^HHXZ܈B[XܙX\[[[ۘ\H[[][ۋ]\B\\]ܞH\\[YXوH[Y\H[Z]Y\HYXۈ[[][ێ[Y[š]HX\YYXۈH\[ݘ\[\\[B]X^H]\HHXܙX\H[H\\[ۈقH[[\ܙ[\XܙX\[Y[[]\H\Y\˂HYXو[YۈH\[ݘ\[\\[B\H\^[\[[ۈH[Y[B\Y H NNN K]\H[Y\Y\[[ZX[[[[ؚ[^][ۈو[YH[\[B]\H\[ZX[[[ۘ\H\ۜX[ۂZY NNLX\][ NNLX\][ NNM”[XY Y[X[ NN JHHZ]\X]][B[\]]X\\\[H [ۈ ۙBNNLNX\][ NNLX\][ NNM]YX\[[] NN H܈XHH]\[H[X\Bو\[Z[H Z[H][ NNLX]\ NNM K\B\[\YX[\[[HXܙX\H[\\[ۈوH\Y\[[]\H[[][ۂ\\[ۈZ\X][܈[[و[B[[HXܙX\H[Y[Y\[ۈXܛB[[\Y[X[H [ NNLK]YY\]B\\Y[[ۘ\H[[[Y[Y\[ۈ\[[Y[[[ؚ[^][ۈو[[X[ˈ›وHYY\]]HۙH]Hۈ][Y[[[ؚ[^][ۈ]\\HXܙX\H[Y[Y\[ۈ[[[[ؚ[^Y[\ [\][ H[[\[ [][ NNMK[Y]X\ۛۈX]H]\X[۝و\\][ۋ[HYXو[Y›ۈ\۝ H]\[[ܙH[Yܘ]]B[\[[وHYXوH[Yۂ\[\\\]ܞH۝[[[ۈ\YYY \XX[HY[ܙHYX]HX]Y[܈[Y B[XY\\]ܞH\\[ۈ\HH\X\Y \X[\H\[[ZX[[[[ؚ[^][ۋY\[\[[ZH[^HKX\ˈ NNMˈST B\[[]\[و[Y H[Y[[[YYX]Y\\[ۈوH\]Y\\]ܞH]ܚ[]؛ܛ]ˈ\[ L  LLL HK NN [X[\XXHو[Yۚ\ق\XZ[XY\\]ܞH\\[ۋHYY]Y]ˈX]B\H L M͋HK NNN Y\HYXو[YYۚ\[Yۚ\ X[Yۚ\[[Y\\XKYY]H NN MLNK[XYZ\HK]Y\QX]HQ] NNM]Y[H܈3 K[[YX\܈[[Y[[[[[ BYYX]Y\\]ܞH\\[ۋ]\\XX L KL ZY NNL [Y[X[YYX[K[ YY N LKM L˂ZHKZYH^ZHK ]\\XXBو۝و\\]ܞH]H[]\[X]\BX[[X[ˈ\XX \\]]  L Z[Hܝ[Z[SKZX[ NNLX]HX[ۈ[H[[ۘ\H\[][ۋ[K\XX N MNKLMK[ۈ ۙHK NNLK\[ݘ\[\[[[ۘ\BYXو[ܜ[H[ۜ[\Yˈ[K\[ Y