AIRWAY ASSESSMENT

Management of the airway in all groups of patients, whether spontaneously breathing or ventilated, unconscious or awake, is one of the corner stone of the anesthetic practice. There is no substitute for experience based on sound theoretical knowledge.
Assessment of airway is paramount in every patient, whether it is the intention to give a general, regional or local anesthetic because complications can occur in the most unexpected way. The combination of unable to ventilate/unable to intubate is a dreaded complication during administration of anesthesia.
To avoid this situation the assessment of airway, preparation of equipment and plan in case of difficult airway is desirable.

LARYNGOSCOPY AND INTUBATION IS EASIER IF:

1. Patient can open his or her mouth and protrude the tongue to enable the whole of the uvula and posterior pharyngeal wall to be seen.
2. If interdental distance at incisors is equal to or greater than 3.5 cm.
3. If he or she can easily adopt "sniffing the morning air" position (neck flexion with extension of the head)
4. If he or she can protrude the lower mandible beyond the maxilla .
5. If he or she has normal head and neck anatomy and normal dentition or completely absent upper and or lower dentition.
   
6. If he or she is not grossly obese.

DIFFICULT INTUBATION IS SUGGESTED BY:

1. History of previous difficult intubation..
2. High palate with crowded teeth.
3. Loose teeth and small mouth
   
4. Reduced mouth opening with small interdental distance
5. Large protuberant upper teeth
6. Receding chin/short mandible.
7. Immobile neck with restricted head movement.
8. Obesity.
9. A short or bull neck
10. A larynx that does not fall normally on swallowing.

THYROMENTAL DISTANCE:

• This is the distance between the upper border of the thyroid cartilage and bony point of chin.
• Short distance indicates an anterior larynx.
• A distance of about or greater than 7 cm is associated with easy laryngoscopy.

MALLAMPATI / SAMSON-YOUNG CLASSIFICATION OF OROPHARYNGEAL VIEW:
Here, the anesthesiologist sits in front of the patient and ask him to open his mouth and stick his tongue out:

• Class 1- Uvula, faucial pillars and soft palate are visible
• Class 2- Faucial pillas and soft palate are visible
• Class 3- Soft palate and hard palate are visible
• Class 4- Only the hard palate is visible

If the faucial pillars, soft palate, posterior pharyngeal wall are visible, laryngoscopy will probably not be difficult. If only the hard palate is visible, it probably be difficult.

CONCLUSIONS:

1. "Not able to ventilate/Not able to intubate" though occurs rarely, but it can endanger the life of patient and put the anesthesiologist in the most difficult times of his carrier.
2. So, the assessment of airway in every patient is a MUST and should NEVER be ignored.
3. CAPNOGRAPHY and OXIMETRY are the MOST DESIRABLE monitors in the difficult airway patients.
4. When difficulty arises, ADEQUATE OXYGENATION of patient is the MOST IMPORTANT OBJECTIVE.
5. Never hesitate to call for help in a difficult situation.
   

SPINAL ANESTHESIA-Technique And Clinical Pearls..

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LARYNGOSCOPE AND ITS COMPLICATIONS

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MANAGEMENT OF ACCIDENTAL EXTRAVENOUS INJECTION OF I/V INDUCTION AGENT

EXTRA VASCULAR/SUBCUTANEOUS INJECTION:

1. Most I/V induction agents (and especially barbiturates because of their alkalinity) are irritant when injected extravascularly.
2. The extent of pain and damage depends upon the volume and concentration of the injection. These can vary from minor irritation and erythema to sever pain, tissue necrosis to sloughing
3. Pain can be elevated by infiltrating the area with 1% lignocaine (without vasoconstrictor), the penetration of which can be assisted by addition of hyaluronidase.
4. Vasodilation and comfort are aided by warm compressed and simple analgesics.

INTRA-ARTERIAL INJECTION:

1. This can lead to serious damage to the blood supply of the affected limb with permanent ischemic sequelae.
2. The consequences of intra-arterial injection of other drugs such as antibiotics can be just as disastrous as those of barbiturates
3. The classic response is immediate and agonizing pain shooting down the arm into hand and fingers. The severity is such that it is unlikely to be caused by any other event during induction
4. The pain may subsequently last for a short time, be persistent or return later, presumably because of attacks of vascular spasm.
5. After the pain, the limb blanches, the pulse disappears and the limb then becomes mottled and cyanosed.
6. An intense chemical arteritis develops and there may be crystal deposition in small vessel.
   

MANAGEMENT:

1. On suspicion, immediately stop the injection
2. Leave the needle or cannula in vein.
3. Into the artery inject lignocaine 100 mg and papavarine 40 mg in 10-20 ml of saline
4. Give 4000 IU heparin I/V (unless otherwise contraindicated or unless a sympathetic block is to be done immediately
5. Keep the limb warm to encourage vasodilation
   
6. Consider the sympathectomy by local anesthetic e.g. stellate ganglion block.
7. Long term management depends upon the extent of damage and may involve limb salvage surgery or plastic reconstruction
   

I/V INDUCTION OF GENERAL ANESTHESIA - SUMMARY

BASIC PRINCIPLE:-

1. From the patients"s view point,induction of anesthesia is very important time, partly because anxiety is maximal especially in unpremeditated person. So, there should not be any UNDUE DELAYS and that the ENVIRONMENT IS PEACEFUL, gives an impression of confidence and HAS NO DISTRACTING NOISES.
2. The basic principle is to induce anesthesia in a PROPERLY EQUIPPED ENVIRONMENT WITH A PROPERLY TRAINED ASSISTANT. Anesthesia should NEVER be induced WITHOUT SUPPORT.
3. All routine patients should be induced with an ECG, PULSE OXIMETER AND A NIBP cuff in place
4. There should be a RELIABLE I/V ACCESS.
   

ELECTIVE I/V INDUCTION:-

1. A great advantage to the anesthesiologist is the RAPID PASSAGE from consciousness to the plane of surgical anesthesia with few excitation side effects.
2. Doses of I/V induction agents are predictable for population, but not for individuals. TITRATION TO RESPONSE is the key to success for individual patient
3. PRE OXYGENATION is often recommended and is MANDATORY for emergency cases and patients with difficult airway.
4. Pain on injection if experienced, make sure that injection is not going S/C or intra-arterial.
5. The GREATER THE DOSE of drug and the FASTER the injection rate, the quicker the sleep is induced and the MORE ADVERSE the physiological SIDE EFFECTS.Practical experience is the best guide as to how fast to induce anesthesia in particular patient, the less fit responding BEST to SLOW INDUCTION
6. ALWAYS ALLOW SUFFICIENT TIME for the induction agent to act in patient with a SLOW CIRCULATION TIME.
7. Remember that an I/V induction administers a potent drug to a patient and from then onwards, the anesthesiologist has no control over the subsequent actions and pharmacology of the agent. This contrasts with the volatile agents which can be removed by ventilation.
   

ALTHOUGH MINIMAL MONITORING IS REQUIRED, NOTHING REPLACES A VIGILANT ANESTHESIOLOGIST WITH HIS OPEN EYES AND EARS AND THE FINGER ON THE PULSE OF THE PATIENT.

CLINICAL PEARLS:

1. It is a bad practice and produces a risk of AWARENESS for relaxants to be given before consciousness is lost.
2. It is vital, once consciousness is lost, to achieve immediate control of airway and to ensure a continued supply of oxygenated gas to the lungs.
3. The insertion of an oral airway should not be done in an unrelaxed patient in a lighter plane of anesthesia
4. Patient fails to go to sleep when:

• the cannula is not in the vein
• There is venous obstruction (e.g, inflated tourniquet)
• The wrong drug has been given.
• The drug is taking an unusually long time to reach its target receptors because THE CARDIAC OUTPUT is SERIOUSLY LOW.
• It is very easy TO OVERDOSE SICK PATIENTS BY FAILING TO WAIT LONG ENOUGH FOR A RESPONSE.