Week 7 - Anesthesia for ophthalmic surgery

Question 1

Goals in ophthalmology anaesthesia (5)

Answer 1

• Production and drainage of aqueous humour
• Intraocular blood volume (arterial blood pressure, vascular tone, venous drainage)
• Body position
• Extraocular muscle tone
• External pressure

Question 2

Intraocular pressure (IOP) is influenced by: (5)

Answer 2

1. Aqueous humor fliud dynamics
2. Choroidal blood volume
3. Central venous pressure
4. Vitreous humor volume
5. Extraocular muscle tone

Question 3

What drugs reduce IOP?

Answer 3

Most anesthetic drugs decrease IOP

Barbiturates reduces IOP primary - relaxation of extraocular muscles

Thiopental reduce IOP

Question 4

What drugs increase IOP?

Answer 4

Ketamine, propofol, alfaxalone cause increasing of IOP

Question 5

Ophthalmological patient are frequently treated with carbonic anhydrase inhibitors /control of IOP - what can this cause & how to prevent it ?

Answer 5

Ophthalmological patient are frequently treated with carbonic anhydrase inhibitors /control of IOP/ – they cause acidosis!

Treatment of acidosis before! anesthesia – IV application of fluids – bicarbonates

(Physiological compensation of acidosis – hyperventilation
During the anesthesia is present hypoventilation – worsening of acidosis)

Question 6

Oculocardiac reflex can cause …

Answer 6

Oculocardiac reflex cause bradyarrhytmia and cardiac arrest

Question 7

Protection against oculocardiac reflex

Answer 7

premedication with atropine (0,02 mg/kg IM or SC)

If the bradycardia or cardiac arrest occure during the anethesia – stop with eye ball manipulation, IV application of atropine

To avoid tachycardia caused by atropine – ½ doses give IM, ½ doses give IV!!!

Question 8

In ophthalmic anaesthesia what kind of catherisiation should not be used

Answer 8

Don´t use jugular catethrization

Question 9

If the intubation is difficult during ophthalmic anaesthesia what can increase?

Answer 9

If the intubation is difficult – marked increasing of the IOP during surgical period

Question 10

All inhalant anesthetics (metoxyflurane, halotane, isoflurane) – reduce IOP by how much roughly?

Answer 10

30 – 50 % as in awake status

Question 11

For quiet eye what should be used?

Answer 11

using of peripheral muscle relaxants

Atracurium or vecuronium – peripheral muscle relaxants

Question 12

Name 2 peripheral muscle relaxants

Answer 12

Atracurium or vecuronium

Question 13

After application of peripheral muscle relaxants what should be applied ?

Answer 13

After application of peripheral muscle relaxants – mechanical ventilation of the patient

Adequate ventilation – airway pressure 10 – 15 cm H2O
Ventilatory frequencies – 8 – 12 breaths per minute

Question 14

To reverse effects of peripheral muscle relaxants ?

Answer 14

atropine (0,02mg/kg IV) followed by neostigmine (0,02 mg/kg IV)

Important – quiet recovery!!!

Question 15

Many of what drugs have been shown to reduce tear production.

Answer 15

Many opioid analgesics, sedative drugs and anaesthetic agents, including pethidine (meperidine), fentanyl, butorphanol, morphine, medetomidine, desflurane, isoflurane and sevoflurane, have been shown to reduce tear production.

Question 16

Infiltration anaesthesia -> Local anaesthetic solutions are deposited around the area to be desensitized by multiple intradermal and/or subcutaneous injections.
NAME 2

Answer 16

n.auriculopalpebralis
Retrobulbar block

Question 17

Why we never use topical anaesthesia in ophthalmic anaesthesia ?

Answer 17

inhibit corneal re-epithelialization,
interfere with lacrimation
and may produce corneal swelling and increased permeability

Question 18

Methadone duration
(opioid)

Answer 18

3-4 hrs
i.v, , i.m, s.c.

Question 19

Byprenorphine
(opioid) duration

Answer 19

6-8 hrs
i.v, i.m, s.c.

Question 20

Butorphanol
(opioid)

Answer 20

1-2 hrs
i.v, i.m, s.c

Question 21

Meloxicam administration methods
(NSAID)

Answer 21

I.v, s.c

Question 22

Carpofen administration methods

Answer 22

I.v, s.c