Operating Department Practitioner
Anaesthetic and general topics

Adam's regulator

Pressure reducing valve at anaesthetic machine gas outlet (12 psi).

Adjustable Pressure Limiting Valve

Expiratory relief valve, to protect patient's lungs against high breathing gas pressures during spontaneous breathing.

Anaesthesia

Loss of sensation, to relieve the patient from awareness, pain, or muscle control.

 EpiduralInjection of a local analgesic into the epidural space, blocking the spinal nerves.
GeneralUnconsciousness induced by inhalational, IV, or a combination of both techniques.
LocalLocalised application of topical or injected analgesic.
 RegionalTypically, an analgesic blocks sensation to a complete limb.
 SpinalInjection of local anaesthetic into the cerebrospinal fluid of subarachnoid space around the lower spinal nerves.
 TIVATotal Intravenous Anaesthesia

Anaesthesia tutorials

 totw.anaesthesiologists.org

Anticholinergic

See  antimuscarinic

Anticholinesterase

Drug (eg, Neostigmine, Distigmine, Pyridostigmine) which inhibits acetylcholinesterase, preventing it from metabolising acetylcholine. Result is increased levels of acetylcholine, with consequent reduction of muscular block from agent, such as Atracurium. Also prolongs action of Suxamethonium. Has muscarinic side-effects, which are antagonised by Atropine.

Anticoagulation

Using a drug to reduce the chance of a blood clot forming, such as when helping to prevent a stroke from occurring. Commonly used anticoagulant drugs are Heparin and Warfarin.

Antiemetic

Drug to relieve nausea/vomiting, often caused by emetogenic agents, such as opioid analgesics and nitrous oxide.  More

Antimuscarinic

Anticholinergic Drugs, such as Atropine and Glycopyrronium, which reduce muscarinic effects of Neostigmine, and prevent bradycardia and hypotension associated with Halothane, Propofol, and Suxamethonium. Also, drugs which reduce intestinal motility eg, in management of irritable bowel syndrome.

Antispasmodic

Relieves/prevents muscle spasms.

ASA rating

American Society of Anaesthesiologists rating scheme for the physical state of a patient.

ASA grades
INormally healthy individual
IIA patient with mild systemic disease
IIIA patient with severe systemic disease which is not incapacitating
IVA patient with incapacitating systemic disease which is a constant threat to life
VA moribund patient who is not expected to survive 24 hours with, or without, an operation
EAdded as a suffix for emergency cases

Atrial fibrillation 

See  Emergencies

Auscultation

Listening to internal organs.

Backslab

A plaster of paris cast which has been cut in two, leaving half of it remaining. The backslab serves as a temporary cast, immobilising the area where it is applied, but also allows access for inspection of the wound, and removal of sutures.

Barbiturates

Group of sedative and hyponotic drugs, such as Thiopentone and Methohexitone.

Barotrauma

Injury due to excess pressure in tissues.

Benzodiazapines

Drugs used for sedation, anxiety relief, muscle relaxation, anti-convulsive. For example: Midazolam, Oxazepam, Diazepam, Lorazepam. Reversed by Flumazenil.

Beta (β) blockers

Beta-adrenoceptor blockers: Negative inotropic drugs which block the affect of Adrenaline on the heart and blood vessels, by weakening effects of the Sympathetic Nervous System on heart conductivity, and reducing blood pressure and heart rate.  More

Bier block

Intravenous regional anesthesia where an extremity, such as a leg, is made numb for surgery, by injecting a local anaesthetic into a vein, after the blood has been squeezed out of the extremity, and a tourniquet has been placed distal to the surgical site. Typical anaesthetics used are 0.5% Prilocaine or 0.5% Lignocaine. A typical adult dose for a leg is 50-60 ml, and 40 ml for an arm.

The tourniquet prevents the local anaesthetic from leaving the extremity, and blood from entering it, giving the patient a numb extremity, and the surgeon a bloodless field in which to work. The tourniquet should be inflated to a pressure at least 50 mm/Hg above the patient's systolic blood pressure. There is a time limit of 1-2 hours on the application of a tourniquet, due to the oxygen starvation which occurs in the region which has an impeded venous flow. If the tourniquet is released whilst a large amount of the anaesthetic is yet to be metabolized, blood toxicity may result.

Blood collection

 Details

Blood transfusion

Transfusion of blood is governed by the Blood Safety and Quality Regulations (2005), which describe all stages of  transfusion, from donation to patient adminstration. Problems with transfusion must be reported according to the  SABRE protocol.   Blood description and testing

Broviac line

A centrally inserted venous catheter to provide intravenous administration - similar to a Hickman line.   Details

Caesarean Section

 G.A. setup  ||  Complications

Cannula

A hollow needle, inserted into a central or peripheral vein, to facilitate intravenous fluid administration.
 Tutorial 1   ||   Tutorial 2

Cardiac drugs

For cardiothoracic procedures, drug and venous access preparation is different from other types of surgery.  More

Cardioversion  

The conversion of an arrhythmia, such as Atrial fibrillation, to a sinus (normal) rhythm, using an electrical defibrillator or by pharmacological means.  Details

Cell salvage

Re-infusing a patient's own blood, which has been salvaged.  Details

CEPOD

Confidential Enquiry into Perioperative Deaths:

GradeNominationDescription
1ElectiveOperation at time to suit Surgeon,Anaesthetist, and patient.
2ScheduledOperation within 24 hours. Delayed operation after resuscitation.
3UrgentOperation between 1 and 3 hours. Early surgery preferred, but not life saving.
4EmergencyOperation within 1 hour. Immediate operation or resuscitation simultaneous with surgical treatment.

Colloids

Intravenous fluids which help to support blood volume, and will not cross semi-permeable membranes (unlike crystalloids), such as capillaries, but will remain within the cardiovascular system.

Examples...
  • Dextrans 40
  • Dextrans 70
  • Gelatin
  • Hydroxyethyl Starch
  • Volulyte

Note: Colloids are not as good as crystalloids for correcting electrolyte imbalances.

Coma

Unconsciousness, where the patient cannot be aroused, has no normal eye movements, and does not respond to stimuli, such as pain.

Combined Spinal/Epidural

Offers the fast onset time of a Spinal (sub-arachnoid block) anaesthetic, with the advantage of topping up offered by an Epidural anaesthetic. See  Anaesthesia UK

Crystalloids

Intravenous fluids which cross semi-permeable membranes, thereby useful for correcting electrolyte imbalances.

Depolarising neuromuscular block

Persistent depolarization of skeletal muscles, making the muscle fiber resistant to further stimulation by acetylcholine.

Diuretic

An agent, such as Furosemide, which increases urine excretion/production.

Drop factor

Drops per ml (millilitre) of fluid administration sets.

Common drop factors...
  • 10 drops/ml (blood)
  • 15 drops/ml (blood)
  • 20 drops/ml (crystalloid)
  • 60 drops/ml (microdrop)

Drug administration

 Example

Drugs

General drugs in  anaesthesia.
Drug  reference
Emergency drug calculations

Epidural block

Epidural: outside the Dura Mater. In anaesthesia, the injection of a local analgesic into the epidural space, to block the nerve routes from the spinal cord. Used in procedures involving the lower limbs, pelvis, perineum and lower abdomen. Also commonly used to alleviate pain in childbirth, usually started during labour, and given before the neck of the womb has started to dilate.
Setup   ||   Basics   ||   Technique   ||   Tutorial

Fasting: pre-anaesthesia

Pre-operative fasting for elective surgery:
Adults: 2 hours for water; 6 hours for solids and milky drinks.
Children: 2 hours for water; 4 hours for breast milk; 6 hours for solids and other types of milk.
 RCN guidelines

Fetching the patient

Policy for "fetching" elective patients.  Example protocol

Gas cylinders 

High pressure gas cylinders are colour coded, for safety. The following colour coding will, eventually, be superceded by a new EU scheme:

Gas Cylinder colourShoulder colourPin index
AirGreyBlack & white1,5
Carbon dioxideGreyGrey1,6
EntonoxBlueBlue & whiteCentral
HelioxBrownBrown2,4
Nitrous oxideBlueBlue3,5
OxygenBlackWhite2,5

 

Gas supplies

Typical supplies to a theatre are: Air, Oxygen, and Nitrous Oxide, at a pressure of 400-500 kPa.

Hartmann's solution

Colloid balanced salt solution, used mainly for general extracellular fluid replacement. Contains calcium, chloride, lactate, sodium.

Health and Safety at Work Act

Imposes duties on employers and employees to protect all persons from harm, whilst at work, and mandates requirements for Welfare at work.  The Act

Hickman line

A central line which allows intravenous administration, and blood sampling. The line is inserted through a vein (neck or chest), and tunnelled under the skin, to it's exit point at the shoulder or chest. There will be 1-3 lumens.
Derby Hospital  ||  Macmillan

ICU bed

Before leaving theatre, patients destined for Intensive Care Units must be transported on special beds, which must be checked for the following:

Checks...
  • Suction equipment
  • Ventilator
  • Oxygen cylinder
  • Monitoring equipment
  • Mapleson C
  • Ambu bag

Infusion pump

A machine which infuses fluids and medications at a pre-determined rate. Can be used for IV, epidural, arterial, or subcutaneous infusions.

Inotropic

A substance which increases the force of muscular contractions, particulary of the heart muscle.

Intraoperative Cell Salvage

Also known as autologous blood salvage; a medical procedure involving the recovery of blood lost during surgery, and re-infusing it into the patient.   More
 Online course

Intravenous drip

Equipment which delivers intravenous fluids/drugs at a rate set by manipulation of a thumb wheel.

Local anaesthetic toxicity

See  Emergencies

Minimum Alveolar Concentration (MAC)

Minimum concentration of an anaesthetic agent in the alveolus, at 1 bar pressure, which produces no response in 50% of subjects exposed to a surgical stimulus.

Naloxone

An opioid antagonist, which counters depression of the central nervous system, caused by opioids.

Nasogastric tube

A tube which is passed through the nose to the stomach, allowing stomach contents to be drained into a bag. A nasogastric tube weakens the effect of the gastrooesophageal sphincter, and makes regurgitation of stomach contents more likely, shown by increased intragastric pressure. The increase in pressure is the basis of vomiting, and may be decreased if the intragastric pressure can be reduced. Do this by allowing the tube to drain freely, so fluid moves up the tube to the bag.

Nerve block

Injection of a local anaesthetic agent close to a peripheral nerve or nerve plexus.

Nerve stimulators

Administer electrical stimuli to peripheral nerves eg, wrist ulnar. Strength in Coulombs (product of amps and seconds). Typical current is 6 mA, over 0.2 mS, with resultant charge of 1.2 µC. Stimulus longer than 0.3 mS can produce repetitive nerve or muscle stimulation. Less charge to deliver supramaximal stimulus necessary when negative electrode placed distally.

Non-depolarising block

Non-depolarising muscle relaxant drugs compete with acetylcholine (ACh) molecules, released at the neuromuscular junction, to bind with nicotinic receptors on the post synaptic membrane of the motor endplate. These drugs block the action of ACh, which prevents depolarisation/contraction of the muscle. These blocking agents relax the diaphragm, abdomen, and vocal chords. The patient, therefore, will require assisted ventilation during anaesthesia.

Muscle groups differ in their sensitivity to muscle relaxants; the ocular muscles, which are responsible for moving the eyes, are the most sensitive, followed by the muscles of the jaw, neck, limbs, intercostals, and abdomen. The diaphragm is the least sensitive muscle, which is why patients undergoing surgery sometimes hiccup or breathe, as an early sign that the relaxants are wearing off. The reversal agent for the block is Neostigmine - an anticholinesterase.

Obstetrics

 Handbook

Paediatric Anaesthesia

Anaesthesia UK

Patient controlled anaesthesia

Intravenous infusion of analgesia, controlled by the patient, using a  syringe driver, such as the Graseby pump.

Patient transfer to operating table 


The priorities are...
  • Manage the airway
  • Monitor oxygen saturation
  • Prevent nerve and pressure point damage
 More

Patient positioning

 Basic notes

Peripherally Inserted Central Catheter (PICC) 

A peripherally inserted central catheter is an alternative to a centrally inserted line, and can be used for prolonged periods, to provide IV access and total parenteral nutrition.
The PICC is inserted into one of the large peripheral veins (near the elbow), such as the cephalic, basilic, or brachial veins, and then advanced through increasingly larger veins, towards the heart, until the tip rests in the distal superior vena cava or cavoatrial junction.

Precordial thump

An attempt to interrupt an arrhythmia, such as Ventricular Fibrillation or pulseless Ventricular Tachycardia, by making a single strike, with the fist, to the centre of the patient's sternum. The thump is only effective if made at the onset of a witnessed and monitored adverse rhythm (VF/pVT), and a defibrillator is not immediately available. Latest resuscitation guidelines de-emphasise use of the precordial thump.

Primary survey

Steps to take when assessing an unconsciousness patient.

Order of steps
StepDescription
DangerAssess Dangers to yourself and casualties
ResponseUse the Glasgow Coma Scale to ascertain the level of consciousness
AirwayExamine the Airway for obstructions
BreathingLook, listen, and feel for adequate respiratory effort. Supplement with oxygen to correct hypoxia, if saturations are below 95%
CirculationIf a carotid pulse is not palpable, then resuscitation should be commenced

Rapid Fluid Infusion

The rapid intravenous introduction of fluids, such as saline or blood products, into the haemodynamically unstable patient, with the aim of correcting hypovolaemia and hypotension.   Belmont manual   ||   Setup

Regional anaesthesia

Anaesthesia affecting only a part of the body, typically a limb. Generally involves the introduction of local anaesthetic to block the nerve supply to a part of the body, such as a leg. Unlike general anaesthesia, patients may remain awake during their procedure, resulting in reduced side-effects, and enabling the surgeon to converse with the patient during the procedure.

Regional block types...
  • Central eg, epidural and spinal (neuroaxial)
  • Peripheral plexus eg, brachial plexus
  • Peripheral single nerve
The anaesthetic agent may be given in two ways:
  1. Injection directly into a vein, which has it's venous flow impeded by a tourniquette.
  2. Intravenous continuous flow  (Bier block), via a catheter, eg, continuous peripheral nerve block.
Regional presentation

Ring block (field block)

Local anaesthetic infiltration circling the surgical site, without injection into the site itself. The block prevents nerve impulses from leaving the site when, for example, it is undesirable to 'pullute' the site with the anaesthetic agent.

Secondary survey

A more in depth survey of the patient than the primary survey.  Description

Sedative

An agent which relieves tension and anxiety. Commonly used sedatives are the Benzodiazepine anxiolytic agents:

Benzodiazepine sedatives...
  • Diazepam
  • Lorazepam
  • Midazolam
  • Oxazepram
  • Nitrazepam
  • Temazepam
These agents are antagonised by Flumazenil.

Seldinger technique

A method of introducing catheters and probes into vessels.
  • Puncture the vessel with a needle.
  • Insert the Seldinger wire through the needle into the vessel.
  • Remove the needle.
  • Use the Seldinger wire as means of access to the vessel.

Spinal (subarachnoid) block

An injection of anaesthetic agent, typically Diamorphine or 0.5% Heavy Marcaine, into the intrathecal space and the cerebrospinal fluid of the subarachnoid space, around the lower spinal nerves, below L2, so as to avoid piercing the spinal cord.  Details

Subcutaneous cannula

A cannula placed between skin and muscle.

Placement...
  • Insert cannula at a 45° angle
  • Ensure pectoral fin is flat against skin
  • Press in wings to squeeze out needle
  • Replace cap
  • Aspirate at white cap with 10ml syringe - ensure no blood
  • Refit white cap
  • Apply clear Tegaderm dressing

Subcutaneous injection

An injection into the fatty layer between the skin and muscle. Subcut injections are given because there is little blood flow to fatty tissue, and the injected medication is absorbed more slowly. Some medications, which can be injected subcutaneously, include growth hormone, insulin, and adrenaline.  Procedure

Suxamethonium apnoea

Prolonged effect of Suxamethonium, which means a patient may reverse from anaesthesia, but remain paralysed.   More

Sympathomimetics

Drugs which mimic the effects of the sympathetic nervous system, and used in the treatment of cardiac arrest and hypotension.  More

Syncope

Temporary loss of consciousness.

Syringe driver

A portable, battery operated device for mechanical subcutaneous delivery of a drug, at a predetermined rate, and over a specific period. It's purpose is to achieve a steady plasma concentration of the drug. Two commonly used syringe drivers are the Sims Graseby MS26 and MS16A.

Syringe drivers:
ModelLabel colourDescription
MS26GreenDelivery rate at mm per 24 hours
MS16ABlueDelivery at mm per hour

Tachycardia

Fast heart rate/pulse. See  emergencies.

Total intravenous anaesthesia (TIVA)

General anaesthesia using a combination of intravenous agents, but no inhalational gases. A target controlled infusion device controls the dosages, typically consisting Propofol and Remifentanil.  Equipment

Transversus Abdominis Plane block

A local anaesthetic block, to the anterior and lateral abdominal wall, to provide analgesia.
AAGBI   ||   NYSORA   ||   Youtube

Tuohy needle 

A hollow hypodermic needle, very slightly curved at the end, suitable for inserting epidural catheters.  Image

Ultrasound guided continuous peripheral nerve block 

See  Sonoplex

Vasoconstrictor (vasopressor)

A substance which causes contraction of blood vessels, resulting in reduced blood flow and increased blood pressure. Acts directly, or indirectly, on the SNS. Often used in resuscitation, and to treat hypotension in surgical patients.

Example vasoconstrictors...
  • Adrenaline
  • Ephedrine
  • Metaraminol
  • Methoxamine
  • Phenylephrine

Perioperatively, Ephedrine and Metaraminol should always be immediately available. Ephedrine has a faster onset than Metaraminol, but only lasts for about 10 minutes; whereas Metaraminol lasts 20-60 minutes.
Ephedrine is safe for use in pregnancy, as it does not reduce placental blood flow.

Vasopressor

See  Vasoconstrictor

Volatile anaesthetic agents

Anaesthetic agents which are liquid at room temperature, but evaporate easily for administration by inhalation.  
 Colour coding