Aquatics

Question 1

General Considerations for Aquatic Mammals

Answer 1

Drug Delivery = difficult

Cold, aquatic environment - fur coats, thick blubber, or fat layers for insulation

IV Access very limited, even if immobilized or anesthetized

Question 2

General Pulmonary System of Aquatics

Answer 2

Pulmonary systems highly developed to facilitate rapid oxygen, carbon dioxide exchange

Short upper airways with extensive cartilaginous support down to small bronchioles

Take large breaths (tidal volumes) –> aids in rapid gas exchange

Question 3

Dive Reflex - Summary

Answer 3

breath holding (apnea), decreased heart rate, shunting of blood to critical aerobic organs

Question 4

Breathing Pattern Generator in Aquatics

Answer 4

Higher centers in brain modulate central rhythm generator both positively, negatively breathing

During episodic breathing, modulating influences alternate: periods of apnea alternating with periods of relatively high frequency ventilation

Question 5

How Aquatic Peripheral Tissue Changes during Dives

Answer 5

 Reduce metabolic functions or
 Function by hypoxic or anaerobic pathways

Question 6

Implications of Metabolic Changes During a Dive

Answer 6

Absorption of anesthetic can be unpredictable or slower if CNS depressants administered IM during breath holding or during activation of dive reflex

Once breathing initiated, blood flows to the periphery

Darting or drug administration should occur during active ventilation, avoided during apnea

Question 7

When should you dart an aquatic animal?

Answer 7

1. Active ventilation/avoided during apnea
2. Mammals should not be darted with anesthetic while in aquatic environment
   o Can dive out of sight, drown

Question 8

Blowhole

Answer 8

modified nasal orifice (blowhole)

Closed by muscular nasal plug when underwater
 Opens through action of forehead muscles

Divided by septum for 10-12cm

Question 9

Aryteneoepiglottic Tube

Answer 9

Giving direct opening from internal nares to lungs
 Enable animal to breathe only through blowhole

Question 10

Aryteneoepiglottic Tube

Answer 10

giving direct opening from internal nares to lungs
 Enable animal to breathe only through blowhole

Question 11

Distal Airway in a Porpoise

Answer 11

10 cm from base of larynx, trachea branches into separate right bronchus

15 cm, bifurcates into two main bronchi

When intubated, do not extend tube into bronchus ie do not pass tube >10cm

Question 12

Respiratory Pattern in a Porpoise

Answer 12

one full respiration in 0.3s

VT 5-10 L –> flow rates through air passages range from 30-70 L/s during expiration, inspiration

RR 2-3bpm, each breath is deep (~80% tidal air)

After inspiration, animal holds an apneustic plateau for 20-30s then rapid exhalation, inspiration

Question 13

Bradycardia in Porpoises

Answer 13

frequently observed during anesthesia

Preanesthetic treatment with anticholinergics is recommended
 IV or IM dose of atropine = 0.02 mg/kg

May be from strong PSNS stimulation or effects of sedatives or analgesics

Question 14

Sedation of Porpoises

Answer 14

meperidine =0.2 mg/kg IM in cetaceans - meperidine provides moderate restraint in cetaceans without deleterious effects +/- BZD

Question 15

Orotracheal Intubation of Porpoises

Answer 15

Can be intubated while awake, easier after sedation or induction of unconsciousness

Relatively large airways (24-30 mm) ET tube
 Cuff inflated

Question 16

Process of Orotracheal Intubation in Porpoises

Answer 16

 Mouth held open with towels by assistant
 Hand inserted into pharynx and grasps, pulls larynx anteroventrally from normal intranarial position
 Digital intubation similar to cattle: ET tube guided into trachea by inserting 2 fingers into glottis, passing tube along palm of hand

Question 17

Other Forms of Intubation in Porpoises

Answer 17

Blowhole intubation described in smaller cetaceans

Question 18

Maintenance of Anesthesia in Porpoises

Answer 18

Require IPPV

Inhalants > TIVA

Question 19

IV Access in a Purpoise

Answer 19

tail fluke veins

Question 20

Drug Sensitivities in a Porpoise

Answer 20

Sensitivity to barbiturates: respiratory failure, death - no longer recommended

Plasma cholinesterase extremely low or absent in bottlenose dolphins, use of succinylcholine to induce muscular paralysis not recommended

Question 21

Porpoise Parameters under GA

Answer 21

o HR 100-120 bpm
o On 100% O2: arterial pH averages 7.35, PaO2 100-200 mmHg, PaCO2 35-50 mmHg
o Room air, conscious: arterial PaO2 65-98 mmHg, PaCO2, ranges 40-60 mmHg

Question 22

Monitoring of Depth in Porpoises

Answer 22

Cessation of tail-fluke movements = surgical anesthesia
 Occurs after loss of strong corneal and eyelid reflexes

Swimming reflex = best criterion for assessing depth

Question 23

Other Reflexes of Depth in Porpoises

Answer 23

–Palpebral
–Corneal
–Swallowing with pharyngeal stimulation
–Body movements with anus distention
–Tail Movements
–Pectoral flipper movement IRT surface stimulation
–Movement of blowhole after stimulation of nares, vestibular sacs
–Vaginal or penile movement when manipulated

Question 24

Extubation of Porpoises

Answer 24

ET tube kept in place until blowhole reflex returns
 Usually 15-45 min after cessation of inhalant administration

Timing removal of ET tube critical
 Only after animal capable of breathing on own = movements of blowhole/thorax, struggling, coughing, or bucking
o ET tube removed, larynx must be placed in its normal intranarial position

If animal does not exhale through blowhole within 3 min or HR <60bpm, re-intubate and ventilate for a few minutes

Question 25

Porpoise Recovery

Answer 25

near neutral in buoyancy o Out of water = more difficult for them to breath and maintain circulation o Returned to water ASAP post recovery

Question 26

Analgesia in Porpoises

Answer 26

Local anesthesia: analgesia for minor painful procedures o Toxic doses of various LAs not established, use smallest dose possible NSAIDS: carprofen, flunixin – gastric ulcers common

Question 27

Toothed, Baleen Whales

Answer 27

* Chemical immobilization, anesthesia attempted in large cetaceans * Killer whales: sedated with meperidine, midazolam for minor procedures Anesthesia, sedation generally not successful

Question 28

Mortality in California Sea Lions

Answer 28

Perianesthetic mortality of California sea lions under ax = 3.4%, within 72hr post up to 4.3%

Question 29

Respiratory System of Eared Seals, Walruses, True Seals

Answer 29

Highly efficient respiratory systems o Alveolar exchange in seals measured at ~46% vs terrestrial mammals only 12-16%

Question 30

Induction of Eared Seals, Walruses, True Seals

Answer 30

In species that can be physically restrained or sedated with BZD tranquilizers (diazepam/midazolam 0.1 mg/kg IM), induction with gas anesthetics recommended o **Mask inductions can be very fast, as little as 3-4bpm** o **High alveolar exchange, low solubility** * Respiratory monitoring important: ETCO2 * Injectable anesthetic drug elimination = more variable

Question 31

Monitoring in Seals, Walruses

Answer 31

Temperature closely monitored via esophageal or rectal probe o Hyperthermia/hypothermia can occur during physical restraint, sedation, anesthesia, handling outside normal aquatic environment Doppler flow detector: important tool in assessing peripheral perfusion

Question 32

Walruses

Answer 32

High mortality rates with opioids, DA o Most likely from severe respiratory, circulatory compromise when animals out of water o Respiratory arrest common with potent opioids, even +ventilatory support

Question 33

Potential Protocol for Walruses

Answer 33

midazolam 0.1 mg/kg, meperidine 2.2 mg/kg o Prevent vagal induced bradycardia atropine 0.04 mg/kg

Question 34

Drug Access in Walruses

Answer 34

1. IM - hip, epaxial muscles, long needle 3-4 inches 2. IV - epidural venous sinus 3. ETT for emergency drugs

Question 35

IV Access in Walruses: epidural venous sinus

Answer 35

Place like epidural needle: sternal recumbency, wings of ileums can be palpated Needle perpendicular to skin Large walruses: 6 inch spinal Epidural IV for fluids, emergency drugs, anesthetics: small boluses of propofol (40-60 mg) used to relax muscle

Question 36

Maintenance and Intubation of Walruses

Answer 36

Onset of immobilization, HR 80-100 bpm – slows to 60 as anesthesia depends Apnea common: prove ventilatory support **Intubation easiest in sternal with head extended**  Small oral cavities  Digital palpation of the larynx, direct placement of ET tube possible once animal relaxed, mouth pulled open by assistant **Oxygen flow rates, vaporizer settings similar to equine: minimum flow 4 L/min**

Question 37

Immobilization of Southern Elephant Seals

Answer 37

seals generally lethargic o Injected close range with pole syringe, 16-18g needle up to 4 inches in length

Question 38

Drugs Used in Seals

Answer 38

1. Concern for excessive salivation with ketamine 2. Succinylcholine (2.5 mg/kg) has been used to immobilize seals rapidly  Must be used with concurrent analgesic or anesthetic drug administration, ventilatory support 3. Medetomidine, consider reversal with atipamezole

Question 39

IV Access in Seals

Answer 39

Restrained in squeeze cage to access flipper, vein in ventral aspect of flipper  ~3 cm anterior to its posterior for IV administration

Question 40

Meperidine in Sea Lions

Answer 40

provides little restraint of sea lions, causing profound respiratory depression o Low dosages or avoid in sea lions

Question 41

Induction/Maintenance of Seal Lions

Answer 41

Sea lions can **hold their breath for as long as 5 min**  When breathe, intake = enormous, rapid  Respiratory pattern during induction not accurate gauge of CNS depression Post induction, trachea is **easily intubated** for further inhalant, 0.75-1.5% halo/iso usually sufficient to maintain anesthesia

Question 42

telazol in sea lions

Answer 42

Telazol >2.5 mg/kg IM can be fatal in sea lions, hypothermia is commonly observed Apneustic breathing seen post telazol, use doxapram Safe, effective doses: 0.5-1mg/kg +/- ketamine

Question 43

Manatees

Answer 43

Many minor procedures can be performed with proper physical restraint Local infusion for painful procedures

Question 44

Positioning of Manatees

Answer 44

Maintain in sternal if sedated or awake (restrained) **Tail is potentially dangerous if in dorsal or lateral recumbency**  Tail can be restrained by assistants, foam pads

Question 45

Potential Drug Combinations in Manatees

Answer 45

Sedation: midazolam 0.045 mg/kg IM Light GA: restraint **midazolam 0.066 mg/kg IM + meperidine (up to 1 mg/kg IM)** o Flumazenil, naloxone = effective antagonist **Nasotracheal intubation easily accomplished with fiberoptic endoscope** o Scope in one nares, tube in opposite nasal passages o **PPV recommended**, iso maintenance 1.5-2.5%

Question 46

Best sites for IM Injection in Polar Bears

Answer 46

shoulder, neck = best sites for IM

Question 47

Considerations for Polar Bears

Answer 47

1. Potent drug combinations 2. Positioning: avoid excessive pressure on limb m - swelling, lameness 3. Hypometabolic state in the summer 4. reversible protocol

Question 48

Summer State of Polar Bears

Answer 48

hypometabolic state  Characterized by fasting, decreased body temp (93-95 F)  IM mobilizing drug requirements may also be decreased

Question 49

Importance of Reversible Protocol in Polar Bears

Answer 49

Areas where lots of polar bears congregate: important due to risk of predation, also important for mom with cubs Immobilized with Telazol, typically keep their heads out of water better than bears immobilized with opioids  Probably due to muscle extension with use of DA vs relaxed curled body position with use of carfentanil or etorphine

Question 50

Drug Administration and Safety in Polar Bears

Answer 50

Mature bears: darted with 22 caliber blank powered projectors, explosive discharge darts Needle up to 10 cm in length necessary to ensure the IM injection Polar bears notorious for pretending to be immobilized, awaken suddenly

Question 51

**Polar Bear Transport**

Answer 51

**Suspension in a cargo net for recovery can cause acute hypertension (up to 50% increase in MAP), hypoxemia, evidence of stress** Cargo net can restrict ventilation and circulation Should be transported on rigid platform

Question 52

Opioids in Polar Bears

Answer 52

Fentanyl, carfentanil, etorphine all used to immobilize polar bears o Fentanyl IM 0.44 mg/kg, volume needed is too high for adult bears o Fentanyl reportedly provides better muscle relaxation than etorphine o **Naloxone 25 mg to 10 mg of fent, 25 mg per 0.5 mg of etorphine for rapid reversal**

Question 53

Sea Otter Protocol

Answer 53

Most effective combo = fentanyl 0.05-0.1 mg/kg + ACP or DZP (0.1-0.22 mg/kg IM)

Question 54

Capture, Restraint of Seanotters

Answer 54

Manual restraint, nets often effective for capture and examination o Hand injection used in these situations o If restraint possible, mask induction with sevo/iso works well

Question 55

Transport of Sea Otters

Answer 55

body temp to increase during capture o Transported in well-ventilated cages that are iced to help keep animals cool