CC BY
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Maja Drozdzynska, Piotr Skrzypczak, Zdzislaw Kielbowicz, Janusz Biezynski,
Anita Piqtek, Natalia Kosciolek
Department of Surgery, University of Environmental and Life Sciences, Wroclaw,
Poland.
ATTEMPT TO USE THE ANAESTHETIC CONSERVING DEVICE AS A NEW METHOD OF ADMINISTRATING INHALATION ANAESTHETICS IN
DOGS (3 CASES).
Abstract
We report the first clinical application of the anaesthetic conserving device (AnaConDa) in dogs. Anaesthetic conserving device presents new method of administration the inhalative anaesthetics. Observation was performed on three dogs. The goal of our study was to establish the minimal dose of isoflurane (ml/kg/h), needed for keeping the dog under general anaesthesia. Furthermore we tried to compare the classical machine for inhalation anaesthesia with the anaesthetic conserving device. We evaluated the time, needed for changing the end-tidal isoflurane concentration in relation with infusion rate on the syringe pump, the effectiveness of AnaConDa in gass recirculation aspect and the patient recovery time.
Key words: inhalation anaesthesia, dog, isoflurane, anaesthetic conserving device
Introduction
In 2004 a new device was develop and introduce for intensive care units patients (5). It's called, because of it's unique properties the "Anaesthetic conserving device". It represents a new system of administrating inhalation anaestetics. The goal for the producer, which for sure has been achieved, was simplifying work with patients in intensive care units. In order to understand the objective to create such a device we need to imagine what work in ICU looks like and what the problems associated with anaestesia in this kind of patients are.
In ICU there are unique patients, who need very specific care. They are people with serious respiratory problems and cardiac or neurological disorders. They need to be under deep sedation or even anaesthesia for a long period of time. Up to 2004 such treatment was possible only by using intavenous anaesthetic drugs or a big, immobile anaesthetic machine. Both solutions are far from ideal. The use of an inhalation machine is expensiveand inconvenient and it is possible only in a surgery room. One the other hand recent years investigations bring knowledge and make us more aware of the side effects of using intravenous drugs. In 1992 Parke et all described for the first time the "propofol infusion syndrome PRIS", which occurred in children who were treated in intensive care units and received long continuous infusion of propofol (>48hours) in high doses (>4mg/kg) (1). The characteristic symptoms of this syndrome, very often fatal in their results, were: rhabdomyolysis, acute metabolic acidosis, cardial and renal dissfunction. Besides, cardio-, reno- and neuroprotective properties of inhalation anaestetics, which have been proven well
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recently, are very desired for ICU patients (2). Those were two main incentives for creation the anaesthetic conserving device. They combine many useful properties like small, mobile, economic and its enable to use inhalative anaesthetics without an anaesthetic machine.
Anaesthetic conserving device - construction and mechanism of action AnaConDa was used for the first time in clinical practice by Enlund and his co-workers in 2001 (1). One year later Sackey proved his usefulness to intensive care unit patients (5).
Its small vaporizer, which most frequently is located between Y element and
andotracheal tube.
AnaConDa consist of the following:
a) Heat and moisture exchanger, which reduce the heat and water loss and create proper thermal conditions for exchanging anaesthetic drug from liquid state to gaseous state - this is done at the evaporation rod level.
b) Activated carbon lipofilic filter- the device's very important part, responsible for absorbing, storing and subsequently releasing inhalation gas.
c) Waste materials absorbing filter,
d) Evaporation rod.
Anaestetic ( Isofluran or sevofluran) in liquid state is administrated to a miniature vaporizer (AnaConDa) through a tube from a specially calibrated syringe pump. While refilling the syringe we should avoid air bubbles getting inside, as otherwise the risk of overdosing increases. Storing of the anaestetics at room temperature decreases such a risk. The minimal volume of inhalation drug needed for filling the system is 1.2 ml. When the first value is screened on a gas monitor, we can start adjusting the anaesthetic dose in the syringe pump ( ml/kg/h) to the desired level of sedation. During inspiration, gas is being released from the evaporation rod and transported to the respiratory tract of the patient. The expiratory fraction goes through two filters located inside AnaConDa. One of them purifies the air, the other (activated carbon filter) absorbs, stores and releases the gas during a following breath. In this way anaestetic gas undergoes recirculation in 90%. This fact offers at least three advantages: decreases consumption of anaestetic, reduces the costs and atmospheric pollution (3). The manufacturer recommends that AnaConDa should be used for administrating isoflurane or sevoflurane only. It is not recommended for desflurane. Besides, it must be used with a ventilator, a syringe pump, an anaesthetic gas monitor and a gas scavenging system. It's worth mentioning that dead space of this device reaches 100 ml, which makes it unsuitable for pediatric patients. We didn't use it on dogs whose weight is smaller than 20 kg. It's a disposable device, and for hygienic reasons it should be exchanged when used for 24 hours The beneficial fact is that AnaConDA doesn't need any CO2 absorbent, which helps avoid accumulation of highly nefrotoxic A compound .
Task, the aim of the article.
According to our knowledge, English and Polish literature, AnaConDa has been studied and described only in humans and swines (5, 6, 7) We wish to present
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the results of the first trial of AnaConDa in dogs. The main objectives of our study were as follows:
- to establish an isoflurane dose, essential for maintaining general anaesthesia and a surgical tolerance,
- to establish the time that is needed for changing the expiratory isoflurane concentration in relation with the isoflurane infusion rate set on syringe pump,
- to confirm the effectiveness of AnaConDa in gas recirculation,
- and to verify if a simple inhalation anaesthetic machine can be replaced by the anaesthetic conserving device.
Materials and methods
At this moment our research is based on a small group of three clinical patients. Based on the history, the clinical status of every dog and its morphological and biochemical blood examination, the patients were classified to ASA second grade. (table 1, 2).
Table. 1
Anamnesis Dog nr 1 Dog nr 2 Dog nr 3
Breed American Staffordshire Terrier Polish lowland sheepdog German Shepherd Dog
Age 9,5 7 7
Gender Male female Female
Weigh 41 23,5 35
ASA Classification II II II
Type of surgical procedure. Anterior cruciate ligament reconstruction Anterior cruciate ligament reconstruction metatarsal fistula.
Dose of medetomidine 1,6ml 0,94ml 1,4 ml
Dose of propofol 4,1ml 2,4ml 3,5ml
Dose of lignocaine administrated to the epidural space 5ml 4ml 5ml
Dogs received medetomidine (Domitor) intramuscularly in the dose of 0.04 mg/kg. Because the entire surgical procedure was associated with hindlimbs, analgesia in this region was achieved by epidural administration of lignocaine. Anasestesia was inducted with propofol in a very low dose of 1mg/kg. The first15 minutes of propofol operation were used for conecting AnaConDa to the breathing circuit, pre-filling the system and adjusting the infusion rate to a desired end-tidal isofluran concentration. We used a pressure controlled ventilator, which was set to 18-20cm H20 inspiration flow, 12 respiratory rates, and 2:1 inspiratory-respiratory ratio. We measured gas concentration on two sampling ports: one was located at the
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endotracheal tube level (in the pre-AnaConDa region), the other at the Y element level (the post-AnaConDa region).
Table.2
Results of preoperative clinical examination and biochemiacal and morfological
blood examination
Parametrs Dog 1 Dog 2 Dog 3
HR beats/min 80 68 87
RR breaths/min 10 47 12
CMM pink pink Pink
CRT < 2 < 2 < 2
Temperature 38,9 38,5 38,3
Leu. (m/mm3) 7,16 9,60 12,47
Lim. (%) 19,9 25,6 20,3
Mon. (%) 2,5 2,8 3,3
Gra. (%) 77,6 71,6 76,4
Ery. (M/mm3) 6,89 7,17 7,64
Ht (%) 50,2 52,6 55,0
MCHC (g/dl) 31,8 32,3 31,6
RDW (g/dl) 9,1 9,4 9,6
Hb (g/dl) 16,0 17,0 17,4
Tro (m/mm3) 363 267 200
ALP (U/l) 123,2 161,2 100,1
Urea (mg/dl) 40,29 34,7 29,67
AST (U/L) 38,53 21,33 30,58
ALT (U/L) 41 33 38
Creatynine(mg/dl) 1,319 1,279 1,351
Glucose (mg/dl) 90,23 97,99 79,53
Albumins (g/dl) 3,647 3,320 2,937
This was essential for establishing the effectiveness of the device in the aspect of gas re-circulation. Two sampling ports were connected to different gas monitors (5330 Agent Monitor OHMEDA, Capnoagent V9400). We collected the following data: systolic arterial pressure (SBP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), blood oxygenation (SpO2), end-tidal carbon dioxide concentration (ET CO2), isofluran infusion rate (IIR),
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expiratory isofluran concentration on the first(Exp Izo 1) and second port (Exp Izo 2). Arterial pressure was measured with the oscillometry method. Besides, we evaluated the anaesthesia level according to Guedel. classification and observed the electrocardiogram curve. Data was collected every 0 2, 4, 8, 10,15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 minutes.
At the beginning of the surgery, the infusion rate of isoflurane was set to 0.2 ml/kg/h, and when the last sutures were applied, we decreased the infusion rate to 1ml/h and observed how the sedation level was changing.
During our EKG-based observations, we tried to evaluate the relation between isoflurane administration and heart action and we mostly focussed on its cardioprotective properties. The dogs were under continuous observation over the entire postoperative period, and in the meantime extubation time was measured.
Results of researches
Table. 3 Dog nr 1
Intraoperative parameters collection 0 2 4 8 10 15 20 25 30 35 40 45 50 55 60
(IRI) ml/h 0 8 8 8 5 5 5 5 3 3 3 3 3 not not
Exp ISO ETT (%) 0 0,90 1,19 1,55 1,43 0,94 0,89 1,15 1,13 1,12 1,10 0,93 0,92 0,84 0,68
EXP Iso Y (%) 0 0,2 0,8 0,7 0,5 0,4 0,4 0,5 0,5 0,4 0,4 0,4 0,4 0,3 0,3
ET CO2 (mm Hg) 45 44 44 44 44 43 43 43 43 43 43 44 43 42 42
SpO2 (%) 98 98 98 97 98 99 99 99 99 98 98 98 99 98 98
HR (beats/min) 90 87 85 90 96 107 100 96 90 100 106 108 107 79 75
RR (Breaths/min) 11 11 11 11 12 12 12 12 12 12 12 12 12 12 12
SAP (mm Hg) 137 138 139 134 136 132 131 133 121 124 120 116 114 120 116
DAP (mm Hg) 116 102 104 105 100 101 101 98 96 94 90 86 87 89 90
MAP (mm Hg) 84 95 89 90 90 84 86 84 79 77 76 74 69 75 80
Sedation level 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III
CIC - 4,1 ml, Extubation time - 30 min after AnaConDa disconnection.
IRI - Infusion rate of Isofluran on the syringe pump, Exp ISO ETT - end-tidal isoflurane concentration sampling at the endotracheal tube level, EXP Iso Y - end-tidal isoflurane concentration, sampling at the Y piece level, ET CO2 - end-tidal carbon dioxide concentration, SpO2 - blood oxygenation, SAP, DAP, MAP -systolic, diastolic, mean arterial pressure, CIC - complet isoflurane consumption.
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Table. 4 Dog nr 2
Intraoperative parameters collection 0 2 4 8 10 15 20 25 30 35 40 45 50 55 60
(IRI) ml/h 0 4 4 4 4 4 4 4 4 4 4 1 1 1 1
Exp ISO ETT (%) 0 1,78 1,24 1,21 1,15 1,15 1,17 1,20 1,25 1,37 1,50 1,07 0,92 0,81 0,77
EXP Iso Y (%) 0 0,6 0,6 0,6 0,7 0,8 0,8 0,8 0,8 0,7 0,7 0,6 0,5 0,4 0,3
ET CO2 (mm Hg) 45 45 42 42 38 35 36 35 35 35 35 35 35 35 35
SpO2 (%) 96 94 94 94 94 93 94 95 94 94 93 94 94 94 94
HR (beats/min) 99 98 97 83 83 107 105 99 100 101 87 80 74 71 65
RR (Breaths/min) 9 11 11 11 11 11 11 11 11 11 11 11 11 11 11
SAP (mm Hg) 131 141 139 139 142 144 141 136 136 140 136 129 132 126 125
DAP (mm Hg) 107 115 115 117 118 117 117 114 115 113 112 107 108 107 99
MAP (mm Hg) 94 105 105 107 108 109 108 102 103 102 102 99 98 97 89
Sedation level CIC - 3 ml, Extubatio 2/III ii tim 2/III ie - 2/III 10 m 2/III in a: 2/III "ter A 2/III naC 2/III onD 2/III a dis 2/III conn 2/III ecti 2/III on. 2/III 2/III 2/III 2/III
Table. 5 Dog nr 3
Intraoperative parameters collection 0 2 4 8 10 15 20 25 30 35 40 45 50 55 60
(IRI) ml/h 0 7 7 7 7 3,5 3,5 3,5 3,5 3,5 3,5 1 1 1 1
Exp ISO ETT (%) 0 Not 1,40 1,46 1,56 1,23 1,15 1,11 1,09 1,07 1,05 0,85 0,7 0,6 057
EXP Iso Y (%) 0 Not 0,4 0,4 0,4 0,3 0,3 0,2 0,2 0,2 0,2 0,2 0,2 0,1 0,1
ET CO2 (mm Hg) 39 39 40 42 43 41 42 43 43 45 45 46 46 47 47
SpO2 (%) 94 94 95 95 96 95 95 94 94 93 93 94 94 93 93
HR (beats/min) 85 84 82 82 81 75 74 70 69 67 66 68 65 70 76
RR (Breaths/min) 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11
SAP (mm Hg) 126 152 145 155 151 149 154 150 149 140 139 144 143 135 149
DAP (mm Hg) 112 110 120 116 118 121 119 119 121 116 113 110 112 115 114
MAP (mm Hg) 103 105 109 105 108 101 113 109 105 109 109 98 97 98 98
Sedation level 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III 2/III
CIC - 3 ml
Extubation time - 10 min after AnaConDa disconnection Conclusions
All the results and are presented in tables. One of our aims was to establish the isoflurane dose that is needed for maintaining the general anaestesia. The dose of 0.2 ml/kg/h meets this criteria, although we discovered that in this kind of anaestesia model (medetomidine, propofol, epidural injection of lidocaine) the dose of 0.1 ml/kg/g is also is sufficient. Another conclusion is that a 40 minutes' observation period is insufficient to stabilise the end-tidal isofluran concentration in relation to
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infusion rate. In comparison with the inhalation anaesthetic machine, AnaConDa is less flexible in the dose determination aspect and a longer period of time is required to adjust an anaesthetic dose to the desired anaesthesia level. After AnaConDa has been disconnected, , arytmias appeared in two out of three dogs, which may indicate that isoflurane has got some cardioprotective properties.
More studies in this area are required to confirm our results. There is no doubts that AnaConDa is a useful device, which can be considered as an alternative to the inhalation machine. If it were possible to use it only to achieve mean sedation, which was our second target, the device could be an irreplaceable system for veterinary intensive care patients, who for the safety reason should be kept under sedation for a longer period of time. Hypothetical!/ to this kind of patients could belongs: dogs after complicated cardiothoracic surgeries, animals with upper airway obstruction or subjected to a procedure in laryngeal area, after which a great risk of oedema and subsequent respiratory disfunction occurs or neurological , epileptic or posttraumatic patients.
Reference
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2) Lee HT, Ayuko Ota-Setlik A, Fu Y, Nasr SH, Emala CW. (2004) Differential protective effects of volatile anesthetics against renal ischemia-reperfusion injuryi in vivo Anesthesiology 101; 1313-1324;
3) Nishiyama T. (2009) Saving sevoflurane and hastening emergence from anaesthesia using an anaesthetic-conserving device" ; European Journal of Anaesthesiology 26(1); 35-38
4) Parke TJ, Stevens JE, Rice ASC, Greenaway CL, Bray RJ, Smith PJ, Waldmann CS, Verghese C. (1992) Metabolic acidosis and fatal myocardial failure after propofol infusion in children: five case reports Br Med J 305; 613-616
5) Sackey PV, Martling CR, Granath F, Radell PJ. (2004) Prolonged isoflurane sedation of intensive care unit patients with the Anesthetic Conserving Device. Crit Care Med 32(11); 2241 - 2246
6) Sackey PV, Martling CR, Radell PJ. (2005)Three cases of PICU sedation with isoflurane delivered by the AnaConDa. Paediatr Anaesth;15(10):879-885;
7) Schauvliege S, Bouchez S, Devisscher L, Reyns T, De Boever S, Gasthuys F. (2009) Influence of two different ventilation modes on the function of an anaesthetic conserving device in sevoflurane anaesthetized piglets Veterinary Anaesthesia and Analgesia; 33(3); 230-238
8) Vasile B, Rasulo F, Candiani A, Latronico N. (2004) The pathophysiology of propofol infusion syndrome: a simple name for a complex syndrome Intensive Care Med. 30(3); 522
Стаття надшшла до редакцИ 26.03.2010
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