GA with muscle relaxant
The basic principal is based on a triangle. One side represents perfect muscle relaxation, the second represents amnesia which is achieved with N2O or low concentration of any anaesthetic agent hyperventilation – Alkalosis depressing the awareness column of the Central Nervous System.
Ether 2% N2O or trichloroethylene 1 to 1.5% suffice (Halothane 0.5% muscle relaxant is administered as supplement where necessary Hyperventilation (alkalosis) potentiates both muscle relaxant action + amnesia. The muscle relaxant should be given as and when necessary and not at fixed timing depending on the pharmacological action. Do not use muscle relaxant for last 15 min. one should give small supplement of Thiopentone to achieve the goal. Reverse the muscle relaxant with atropine and prostigmine. It is mandatory. Even 0.25 or 0.5 mg of prostigmine makes an appreciable difference in patients who do not exhibit much relaxant effect.
Some points:
-Closed circuit, carbon dioxide absorber
-Never practice completely closed circuit
-The gas flow should not be less than 4 lit/min.
-Do not completely depend on the carbon-dioxide absorber
-Rising BP and tachycardia + lightness of anaesthesia should be taken as inefficient
-carbon dioxide absorption or elimination
Wednesday, March 25, 2009
Techniques of Anesthesia-GA with Muscle Relaxant
Techniques of Anesthesia-Using Ether
Some important points with regards to using Ether:
Endotracheal Tube
My practical experience with endotracheal tubes...
Always maintain all sizes of endotracheal tubes for infants, small children and adult. Few adult cuffed endotracheal tubes are a must. Nasal soft tubes size 8, 9, 10 can be lifesavers. They should be sufficiently long. They can also be used for passing a Ryle’s tube in an unconscious patient. After threading the Ryle’s tube in a well-lubricated nasal tube is passed in Oesophagus and Ryle’s tube is threaded down into the oesophagus, the nasal tube is withdrawn. If it is difficult to pass the tube nasally, pass the tube orally push the threaded Ryle’s tube and withdraw the soft tube. The oral Ryle’s tube can be railroaded into the nose with the help of catheter fixed snugly in the end of Ryle’s tube. Push the Ryle’s tube, which is stiff. Do not pull the catheter.
In case of difficult intubation a soft portex tube is passed nasally which mostly enters the larynx. Sometimes it remains anterior to the epiglottis, which can be placed posterior to the epiglottis with Magill’s forceps and threaded to enter the larynx. Sometimes the tube gets hitched against the anterior commissure and cannot advance in the larynx and trachea. It can be manoeuvred by slightly flexing the neck, which corrects the angle between the advancing tube and the trachea.
All endotracheal tubes must be washed by you with soap and water and a jet of water forced down the tube to remove all the left over secretions and finally cleaned by brush and water and dried with a towel. This will save your embarrassment when a freshly boiled tube for use shows secretions of the previous case or a foreign body like a cotton swab or even a cockroach, even a nasal turbinate has been recovered.
Nasal endotracheal tube advanced before oral extubation in case of full stomach makes life easier. Sometimes solid food and big blood clots cannot be aspirated from the oropharynx when extubated and the patient struggle for breath. Nasal tube maintains the free airway and allows sufficient time for the patient to vomit out stomach contents if he is conscious and clear the oropharynx.
All tubes should be fitted with female Noseworthy’s connections. Cobb’s connection is only useful in cases with wet lungs when intermittent suction is mandatory. The connection must be tight fitting and of correct size. Do not try to fit bigger connection as it may tear the tube (rubber).
Cuffed ET should not be used all the time. It spares your cuffed tubes. With use of air it is hardly necessary if the bellows or respirator are used. As far as possible do not inflate the cuff. Pass the proper size tube. If the air leaks by the side of tube is more, replace the tube with the next size. Use of cuff can cause oedema and damage to the mucous membrane of the trachea in long duration cases. After placement of ET inflate the cuff yourself. Over zealous Assistants always tend to over inflate the cuff. The over inflated cuff becomes a very strong stimulus and in light plane of anaesthesia it can lead to intense bronchospasm endangering life if not detected. Cases are known where inflation becomes impossible due to bronchospasm and cyanosis start appearing in spite of oxygen rich mixture used to inflate the lungs thus produced by an inflated balloon. The bronchospasm produced by over inflated balloon does not respond to usual bronchodilator treatment like injection of drugs. It only responds to:
-Deflation of cuff
-Removing the ET
-Deepening the level of anaesthesia
The simplest in the situation is deflation of cuff. The remaining methods appear to be dangerous and are not productive. For conduction of cases always have 3 sizes ready. Also do not forget to keep a nasal tube of appropriate size always ready. It is specially important in cases who are overweight, short neck or where the mouth cannot open adequately. Nasal intubation can prove a life saving procedure in all difficult intubations. In a planned case always ascertain the freedom of breathing through each nostril separately. Lubricate the nasal tube thoroughly, do not use force at any stage. You can have two obstructions while passing a tube through the nose, one at the nasopharynx where it meets the Passavant’s ridge and secondly while the tube meets the larynx at its outlet. The first difficulty should be solved by putting a finger in the nasopharynx as you advance the tube to hook it and bring it out into the pharynx, and second difficulty can always be solved by flexing the neck so that the angle of the advancing tube corresponds with the trachea. The difficulty is due to the nasal tube hitching against the anterior commissure. Do not force the nasal tube. It can cause bleeding.
Rubber tubes last about a year or more and hence one should not hesitate to boil the tube for 2 minutes before each case. Discard the tube when the tube shows signs of perish. The boiled tubes before use must be cooled and in emergency cooled under tap water. A case of an adult female is recorded who had an intubation with hot tube. This patient for Thyroidectomy needed Tracheostomy in the postoperative period. This precaution is a must in case of children and infants.
Inspect the tube before giving it for boiling for any foreign body (Cockroach) or debris. Sometimes cotton swabs used for cleaning have been detected. So look down the tube after straightening to find the presence of any obstruction. Unimaginable objects have been accidentally found inside the tube. In small tubes and Oxford tubes run the water through the tube and pass a stillette to ensure perfect patency. One must possess all types of tubes like armoured, nasal, Oxford, infant and special for specific use. If one can obtain laryngeal mask airway all 3 sizes.
Endotracheal tube connectors
One should have sets of different connections like right angle, Cobb’s, and curved as in some situations one requires various angles and various other uses for the connector. A Cobb’s connection can be used when one has to resort to suction intermittently and for giving IPPR with thumb technique and for use as Ayre’s T piece if it is not available. For routine use it is better to have a plastic female nose worthy connection fitted to each tube and a male Noseworthy connection to the catheter mount or the various unidirectional valves can directly connected to Noseworthy connection with metal connectors check the catheter mount.
Tuesday, March 24, 2009
Judge the gravity of the situation quickly and make alterations to techniques or medications quickly
In spite of all instructions and information one is likely to come across patients whose records do not reflect the conditions suddenly detected on operating table. One has to be very cautious about these patients and one might have to change strategy suddenly.
-Patients orthopnoeic
-Patients having difficulty in breathing
-Inability to open jaw
-Tonsil
-Tooth septic with spreading infection
-Patient in CCF or LVF
-Patient in shock state
-Ectopic beats
-Duodenal perforation, bowel perforation, leaking anastomosis
-Abdominal catastrophe
-Oedema face or legs
-Patients very pale due to sudden massive haemorrhage like burst ectopic pregnancy.
All these and many others can change the plan and new strategy will have to be adopted. All the pros and cons must be rapidly thought and may well delay the procedure, than putting ones foot into it.
In a really difficult situation where the decision is likely to end in fatality one should not hesitate to take a second opinion from a senior anaesthetist. There is no need to have feeling of inferiority and shame while seeking the help of a senior.
Do not depend on the nursing staff in the postoperative period
In above all situations it is the duty of anaesthetist to leave full instructions or leave the nursing home after complete recovery and stable condition. Instruction not to remove the airway unless the patient removes it himself is not understood by the nursing staff. Six post-operative deaths have been recorded after a septum operation under GA. The anaesthetist must plan his anaesthesia in such a way that patient recovers complete consciousness at the end or leave the airway in the mouth or insist on surgeon to put small tubes in the nose reaching up to nasopharynx and then pack the nose. These tubes provide airway for emergency (better than no airway at all) and they provide excellent airway at night when the mouth closes and patient does not wake up suddenly choked and has to open the mouth to breathe. Patients are comfortable with tubes.
After planning for lighter anaesthesia at the end I carry out a simple test to find out whether patient has sufficiently recovered. I call it “Gharpure’s test”. Hold the lips of the patient together with both nasal cavities packed. If the patient struggles to open his mouth and succeeds he is in a safe state to be left alone. In patients when the “Safety” polyethylene tubes are put one can test the functioning by listening free breath from the post end (does not touch the post pharyngeal wall and blocks it.) The test can be applied in deeply sedated patients.
In patients who have been given spinal anaesthesia with long acting anaesthetic agents (Bipuvacaine) and surgery gets over in much earlier time (1-2) hours, the effect of the spinal continues for another 3-4 hours. The anaesthetist must instruct the nursing staff about hypotension continuing in postoperative period and its treatment. So many anaesthetist blame the drug. Death has been recorded in the postoperative period. Patient’s blood pressure during surgery is attended to during surgery by the anaesthetist and after surgery the patient is left all alone without instructions.
In smaller setup the commonest cause of postoperative deaths is inadequate reversal of muscle relaxant. Firstly no patient should be shifted from operation table if there is any doubt about his inability to breath. A conscious patient is not a guide for incomplete reversal. A restless patient is always due to hypoxia and not because of pain. A serial B.P. check up every 5 minutes must be done. A rising B.P. is surely sign of incomplete carbon dioxide elimination even though the patient appears pink. A patient who needs assisted respiration in postoperative period with bag and mask needs intubation. A patient who allows IPPR after reversal needs the IPPR.
In all patients with prolonged surgery or toxic patient the presence of qualified doctor is a must. Restlessness in postoperative period should not be translated into pain after surgery but the relevant cause must be found. All patients in whom Lasix was injected during or immediately after surgery, a catheter must be placed in the bladder. Sometimes even a qualified doctor may not be sufficient to understand the cause of restlessness and anaesthetist or operating surgeon must leave instructions rather than testing the intelligence of the house officer.
A diabetic patient on insulin must be under corrected and a small hyperglycaemia accepted rather than hypoglycemia. Covering alternate bottles of glucose 5% infusion with 10 units of soluble insulin is a better plan. Similarly patients with drugs for hypertension given after patient recovers completely and BP checked.
Infants intubated must be closely observed in postoperative period for
Good lusty cry and not a progressive hoarseness
Restless which is mainly hypoxic unless proved otherwise
Dusky colour of skin or mucous membrane. The commonest cause is laryngeal oedema and it calls for immediate treatment and preparation for tracheostomy if treatment fails.
Patients operated for major oral surgery like mandibular tumours of mouth and tongue and tumours of thyroid must be provided an airway at least 48 hours (nasal polyethylene tube with connection) this tube must be removed in the presence of the anaesthetist with all preparations for emergency intubations and IPPR or if found necessary do a tracheostomy. Instances of sudden death in postoperative period are witnessed and documented in such cases. A tongue sutured also prevents falling back of tongue in infants or cases of oral surgery.
All diabetic patients must be converted on soluble insulin regimen if the surgery is major. For minor surgery if the patient is settled on antidiabetic treatment should receive the treatment till previous day and on the day of the operation alternate pint of glucose 5% to be covered by injection Insulin 12 units subcutaneous. The patient goes back to his routine after he starts his oral feeds.
All hypertensives may continue their drug treatment till previous day and after BP check in the morning a dose of nifedepine 10 mg orally under the tongue may be given to check the sudden rise post operatively. All thyroid patients either receiving treatment for hypo or hyper must continue till the day of the surgery. Beta-blockers for thyrotoxicosis must be continued and noted and be informed.
Cases are better worked up by senior surgeons
The situation of postoperative care in smaller nursing home is below standard. Sometimes the operative surgeon is the only resident doctor. In others the theatre sister is the only experienced member in the nursing home. The staff in the ward can hardly be trusted. The best plan is to see that the patient recovers completely on the operation table, the anaesthetist or surgeon stays back till the patient is completely recovered. Some of the most dangerous situations in smaller nursing homes are:
-A major operation done with unstable cardiac and respiratory system
-Patient returned with an airway deeply anaesthetized
-Patient operated for septum with both nostrils packed and no airway provided.
-Long acting agent used for spinal is usually blamed for post operative hypotension which remains unattended.
-Toxic patient with persistent hypotension
-Partially recovered patient from muscle relaxation
-Patient under hypothermia
-Patient operated in oral cavity not recovered fully and no airway provided
-Infants who have been intubated
-Patient operated for upper respiratory tract obstruction.
-Patients on treatment for diabetes or hypertension
-Moribund patient with CVS and RS instability
Patient with previous MI
-Patients heavily sedated, operated under local, suffering from chronic bronchial asthma or chronic severe emphysema.
In the beginning one can expect help from a senior surgeon
In private practice the problems with senior surgeons are minimum. Contrary to popular impressions, they are a great help in preparing the patient and in all stages of anaesthesia. An unscrupulous person is immediately recognized and can be avoided in future. The senior surgeon can tell from his own experience and having worked with senior anaesthesiologist can guide the anaesthetists. They have fair idea about the patients condition during anaesthesia they can recognize from the tissues and the movement of the anaesthetist that something is wrong. They will volunteer help. They from their experience can judge the recovery of the patient. If they suggest that patient is not fully recovered (especially from muscle relaxant effect) it is better to believe them and observe the patient for sometime. The unscrupulous and the junior surgeons should be watched carefully. Beware of surgeons in other branches like dentistry, ophthalmology who are not conversant with anaesthetic complications and hence will be of no help if you are in difficulty.
It is an unrecorded statement that senior surgeon and a senior anaesthetist is the best combination. Senior surgeon and junior anaesthetist or vice versa can be a good workable combination. But a junior surgeon and a junior anaesthetist is a dangerous combination unless proved otherwise. The last combination, both are over confident.
Having worked in teaching hospital after getting the master’s degree gives immense confidence (over confidence) in both surgeons as well as anaesthetist and hence the maximum accident take place during this period. They tend to forget the gravity of the surrounding in which they are working.
Premedication schedule never works due to many variables
Premedication in private practice does not work except with the first case in the morning when anaesthetist and surgeon work at the same nursing home. The scheduled time is disturbed due to:
- Transport difficulties
- Either the surgeon or anaesthetist delayed in the previous case
- Patients relatiives not present
- Patient sent for special exam for ureteric stone or some X-ray investigation needed
- Delay by the theatre staff, equipment
Hence one can depend on premedication on the 1st case only. The rest of the schedule has to be conducted with IV premedication + inductions. Injection Atropine, which was prescribed ½ hour before, does not help in modern practice. It was a must for open drop ether anaesthesia where suppression of salivary secretion was essential. Injection atropine of dryness and some may even start thinking that some extraordinary complications is taking place due to drying and rapid action of the heart and feverish sensation. The olden days premedication for stealing the thyroid in thyrotoxicosis do not apply as they are never taken on table unless sympathetic activity is totally suppressed with anti thyroid drugs.
With IV medication one is assured of
Full administration of drug in system (leaky syringes used by nurses)
Only one injection prick patient feels. This is important in children, as they are very uncooperative for the 2nd injection.
Premedication for infants either by oral or by injection has to be given by ½ hours before induction is by inhalation method. Delayed action like I.V. atropine may not act immediately and appearance of secretion due to endotracheal tube narrow the air passages by secretions.
For patients who are anxious a 10 mg. Diazepam at night or even a tab of diazepam early morning will alleviate the problem.
In patients where induction dose of Thiopentone is likely to be dangerous heavy premedications or basal narcosis is a must, like mitral stenosis patients. Avoid atropine for tachycardia it produces. In very sick and poor risk patients it is better to avoid any premedication.
In some public hospitals the order of patients to be taken for surgery is not known and hence the ward sister gives the injection atropine to all patients at 7.30am as patients are scheduled for surgery at 8.00am (which normally does not start till 8.30 or 9.00 am). The system is followed for years together as anaesthetist insist on atropine ½ hour before. They do not mind delaying the induction till ½ hour is over after injection of atropine is given. I do not understand the rationale behind this plan. Is it because you do conduct less cases in the day and leave early for home? Or is it to show your domination? Nobody is bothered about the suffering of the patient.
Vagolytic action of atropine in pharmacologic doses to prevent vagal arrest is doubted and hence insistence of giving it ½ hour before surgery is sheer ignorance, as IV atropine acts immediately it can certainly replace IM as drying effect is not necessary for IV induction and intubation. If it is given that the 1st drug to be followed by Thiopentone or even mixed with thiopentone (sometimes produces precipitate which dissolves) also acts before scoline and prevents the Cholinergic effect of scoline.
In one infant for congenital cataract the surgeon had prescribed atropine drops in the eye. He did not order oral or sub cut atropine. On arrival we found that atropine drops had produced complete systemic effect with facial flushing tachycardia and dry mouth. Induction with open drop could be take up immediately without injection atropine
Premedication Schedule – never works in private practice except the first case. As you are likely to be delayed, surgeon’s arrival, preparation of OT due to previous operation. Read more on this article...
