12. Medetomidine ketamine anaesthesia in Llamas 2000

Scientific meeting of the European Association of Zoo and Wildlife Veterinarians (EAZWV) Paris, 2000

 

Medetomidine/Ketamine-Anaesthesia in Llamas (Lama glama) – Effect on Anaesthesia Quality, Haemodynamics, Respiration and Metabolism

S.Hammer and K.H.Bonath

Address

Chirurgische Veterinärklinik, Justus Liebig Universität Gießen, Frankfurterstr.108, D35392 Gießen, Germany

 

Summery

The suitability of Medetomidine/Ketamine-anaesthesia in the llama (Lama glama) was examined. Seventeen animals were investigated. After the application of 0.04 mg/kg body weight Medetomidine plus 4 mg/kg body weight Ketamine in a combined intramuscular injection, the effects on the quality of anaesthesia, on haemodynamic, respiratory and metabolic parameters were evaluated under field conditions. Induction, anaesthesia and recovery time were recorded.

The results show that Medetomidine-Ketamine in llamas changes cardiovascular and respitatory parameters which can be compensated adequately by endogenous regulatory mechanisms and do not cause any clinical complications in healthy animals. Muscle relaxation and analgesia proved by body and pain reflexes were good.

 

Zusammenfassung

Die Eignung der Medetomidin/Ketamin-Anästhesie für das Lama (Lama glama) wurde überprüft. Die Untersuchung wurde an siebzehn Tieren durchgeführt. Nach der intramuskulären Injektion von 0,04 mg/kg KGW Medetomidin und 4 mg/kg KGW Ketamin mit einer Mischspritze wurden unter Feldbedingungen die Auswirkungen auf Anästhesiequalität, Hämodynamik, Atem- und Stoffwechselfunktionen untersucht. Einleitung-, Toleranz- und Aufwachphase wurden ermittelt.

Die Untersuchungsergebnisse belegen, dass Medetomidin-Ketamin beim Lama zwar Veränderungen der Atem- und Kreislaufparameter verursacht, die aber durch endogene Regulationsmechanismen kompensiert werden und bei gesunden Tieren nicht zu Komplikationen führen. Anästhesiequalität, Analgesie und Muskelrelaxation, die anhand von Körper- und Schmerzreflexen überprüft wurden, waren gut.

 

Résumé

La qualification de l’anesthésie avec médétomidine-kétamine chez les lamas (Lama glama) a été vérifiée. Dix-sept animaux ont été examinés. Après avoir injecté intramusculaire 0,04 mg/kg masse corporel médétomidine et 4 mg/kg mc kétamine combiné dans une séringue, les effets sur la qualité de l’anesthésie, de l’hémodynamique, des fonctions respiratoires et métaboliques ont été évalués sous des conditions de champ.

Les stades de l’introduction, de l’anesthésie et de la réveille ont été mesurés. Les résultats prouvent que médétomidine-kétamine chez les lamas causent des changements des paramètres respiratoire et cardiovasculaire, lesquels peuvent être compensés par des méchanismes régulatoires endogènes et lesquels ne causent pas des complications chez les animaux sains. La relaxation des muscles et l`analgésie, prouvées par les réflexes de corps et des douleurs, ont été bien.

 

Key words

Llama (Lama glama), Medetomidine/Ketamine-anaesthesia, anaesthesia quality, haemodynamic, respiration, metabolism, anaesthesia time.

 

Introduction

Farm manipulations or veterinary procedures in the llama often need a sedation by  injectable anaesthetic agents (3). Medetomidine is the newest and most potent a 2-agonist, with more specific actions on receptors associated with sedation and analgesia (15). It is usually combined with Ketamine (6,7,13,14). Its effect on haemodynamics, respiration and metabolism has not been tested for llamas under field conditions so far. Atipamezole is a specific Medetomidine antidote(15).

 

Methods

17 healthy Llamas, 9 males and 8 females (6 month to 10 years old) were anaesthetised with 00,4 mg/kg body weight Medetomidine plus 4 mg/kg body weight Ketamine intramuscularly by a combined injection. There was no fasting period before.

The stages of anaesthesia were defined as follows: Induction time from injection to lateral recumbency, tolerance time from lateral recumbency to the return of body reflexes, recovery time from return of body reflex to unconspicuous behaviour  .

The heart rate was checked with an stethoscope and a HELLIGE (multiscriptor EK 43) electrocardiograph at a setting of 2 cm/mV and 25mm/s. The needle electrodes were placed for EINTHOVEN-ECG lead.

The respiratory frequency was evaluated by watching respiration. The arterial oxygen saturation was measured at the tongue by using an ENGSTRÖM pulseoxymeter.

The arterial blood pressure was monitored at the A.femoralis by a clear cuff pressure infusor (MEDEX MEDICAL) joined with a blood pressure machine (GOULD).

Arterial blood was collected from the femoral artery and arterial blood gasses as well as acid base status were measured with the transportable I-STAT blood analyser by using the cartridge EG3+ (10).

To record the body temperature we used a digital thermometer rectally.

All parameters were recorded after the injection of Medetomidine/Ketamine in regular 80 minutes time intervals. For evaluating baseline values, some of the parameters were already measured before the injection.

To assess the quality of anaesthesia various reflexes were tested (5,11,12) and different states of anaesthesia were determined. The time course of anaesthesia was recorded.

 

Results:

The following results were obtained (as mean ± standard deviation or average values) :

–          Average induction time: 3,6 ± 1,5 minutes.

–          Average time of pain tolerance: 60,23 ± 13,8 minutes.

–          Average recovery time: 17,29 ± 7,4 minutes.

–          The heart rate decreased 40 % under the baseline (p<0,001).

–          The mean arterial blood pressure decreased on an average of 12,5 % from time O (10.4 ± 2.7 min after injection), to normal within 50 min (p<0,001). This allows the conclusion to an average 12.5 % increase within the first 10 minutes before.

–          The decrease of peripheral oxygen saturation (p<0,001) from time O (10.4 ± 2.7 min after injection) follows an increase of average 9.5 % within the first 10 minutes  before.

–          Initial arterial oxygen partial pressure ( PO2 ) value was 37% under baseline and returned to normal 40 minutes after monitoring started (p<0,001).

–          Initial arterial carbon dioxyde partial pressure ( PCO2 ) value increased 30% above the baseline and got normal 40 minutes after monitoring started (p<0,001).

–          Arterial oxygen saturation initially lost 16% of baseline and recovered after 40 minutes (p<0,001).

–          The pH decreased 1% under baseline (p<0,001).

–          Internal body temperature was reduced about 0,6% (p<0,001).

All the other examined parameters did not change significantly.

 

Table 1

Measured and clinically recorded parameters (mean ± SD) and monitoring time after injection:

Monitoring

time

Base

line

0

min

10 min

20 min

30 min

40 min

50 min

Heart

rate                            [min-1]

68,8

± 16,89

42,8

± 12,28

41,2

± 10,74

37,9

± 9,91

37,4

± 9,79

42,0

± 12,64

40,9

± 14,43

Mean arterial blood

pressure                  [mmHg]

152,1

± 17,73

150,8

± 18,62

148,3

± 18,43

142,5

± 20,20

140,1

± 24,21

133,2

± 22,35

Respiratory

rate                            [min-1]

22,8

± 9,01

22,6

± 8,60

23,6

± 6,33

24,3

± 9,53

23,8

± 7,24

23,1

± 8,33

23,2

± 5,15

Peripherial oxygen saturation                       [%]

78,8

± 5,24

80,9

± 7,16

83,8

± 4,85

83,4

 ± 6,24

82,8

 ± 8,05

86,2

± 5,69

Arterial oxygen partial pressure                  [mmHg]

87,3

± 16,63

54,7

± 18,59

67,0

± 0,00

74,0

± 21,25

57,1

± 18,42

86,4

± 31,01

72,3

± 23,18

Arterial carbon dioxyde partial pressure       [mmHg]

41,5

± 4,24

53,5

± 4,44

49,9

± 3,39

51,8

± 5,47

50,1

± 4,73

49,2

± 5,05

47,2

± 6,38

Arterial

Oxygen-saturation          [%]

96,1

± 3,47

80,6

± 14,24

93,0

± 0

91,0

± 8,07

86,0

± 7,32

93,4

± 7,14

93,0

± 4,58

Arterial pH

 

7,453

± 0,0407

7,376

± 0,0417

7,440

± 0,0240

7,384

± 0,0203

7,409

± 0,0453

7,413

± 0,0220

7,431

±0,0431

Internal Body

temperature                   [Cº]

37,76

± 0,555

37,72

± 0,607

37,57

± 0,730

37,44

± 0,747

37,10

± 0,891

37,15

± 0,723

 

 

Conclusions:

The results show an initial bradycardia, as a typical side effect in a2-agonists (2,3,11,16). As a sign of endogenous compensation the blood pressure increased initially. At the beginning the respiratory parameters presented hypoxia and hypercapnia. Reasons for this respiratory change probably are physiological and anatomical peculiarities, e.g. the long velum that may cause an obstruction of the nasopharynx under anaesthesia or the influence of different body positions (9). Compared to controlled ventilated llamas  the lung may be hypoventilated in the spontaneous breathing anaesthetised animals(4). The depressive respiration and the very low haemoglobin binding capacity in llamas (8) give reason for the low oxygen saturation.

However arterial pH reached subnormal values only and never lost the physiological range nor it demonstrated respiratory acidosis.

Under Medetomidine-Ketamine-anaesthesia there were no signs of a critical clinical situation due to the cardiovascular and respiratory changes. Blood pressure and arterial pH demonstrate the efficiency of the  endogenous compensatory mechanisms. This makes Medetomidine-Ketamine a safe, rapid and effective combination for the injection-anaesthesia in llamas suitable for smaller surgical and other veterinary as well as farm procedures, which can be recommended as a good alternative to common anaesthetic agents.

 

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