Patients' Guide to General Anaesthesia
- What is a General Anaesthetic?
- Who gives General Anaesthetics?
- How does the Anaesthetist give a General Anaesthetic?
- How Safe is a General Anaesthetic?
- Regional Anaesthesia
- This is when only part of the body is 'frozen' using a local anaesthetic. For example, a whole arm can be put to sleep using an intravenous regional block, or all of the body below the waist can be frozen using a spinal or epidural anaesthetic. These are all types of regional anaesthesia.
- Local Anaesthesia
- This is where only a small area is frozen e.g. freezing the skin so that a cut can be stitched up. Sometimes 'local' is used to refer to regional anaesthesia as well as truly local anaesthesia.
- This means that the patient is given a drugs which make the patient drowsy and relaxed, but not completely asleep. Sedation can often be used with local or regional anaesthesia to help the patient relax.
In Canada, most anaesthetics are given by doctors who, after completing their medical training, take additional training in anaesthesia. Some dentists are also trained to give anaesthetics. Nurses cannot give anaesthetics in Canada, although they do in the USA. In Canada and the UK, doctors who give anaesthetics are called 'anaesthetists'. In the USA, they are called 'anesthesiologists', to separate them from nurse anaesthetists. First of all, the anaesthetist must know what operation you are having, and some things about you and your health. After reviewing your medical chart, the anaesthetist will ask you a few questions to get details of any problems, and to check on your past experience with anaesthetics. The anaesthetist may also want to perform a brief examination. For example, he may want to have a look at your mouth and teeth to ensure that it would be easy to insert a tube into your windpipe, if this is needed.
Next, the anaesthetist and operating room nurses will ensure that you are properly monitored throughout the anaesthetic. In Canada, this means following the Canadian Anaesthetic Society Guidelines. Most countries have similar recommendations. The routine monitors are:
- An ECG (electrocardiogram) monitor
- Three sticky pads on your chest connect to a monitor which shows the electrical activity of your heart on a TV screen. This shows how fast your heart is beating, and allows the anaesthetist to pick up problems such as an irregular heartbeat or signs that the heart is not getting enough oxygen.
- A BP (Blood Pressure) cuff
- This cuff goes round your upper arm. From time to time it will squeeze your arm tight, to find out the pressure of the blood in your arteries. It is important that this is neither too high or too low. An automatic blood pressure machine usually shows four numbers, the high, average, and low pressures with each heartbeat, and the heart rate.
- A pulse oximeter
- This is a device which goes on a fingertip or earlobe, and measures the amount of oxygen in your blood. It works by detecting a slight change in the blood colour from the usual bright pink to blue as the blood oxygen level decreases, long before this change is visible to the naked eye.
- A temperature monitor
- This is an electrical thermometer which checks that you are neither too hot nor too cold.
- A carbon dioxide monitor
- This measures the amount of carbon dioxide in your breath, which shows that you are breathing adequately. It is connected to the breathing tubes coming from the anaesthetic machine.
The simplest anaesthetic consists of a single drug which can produce all these effects for a short period of time. However, it is usual to start with an injection of a drug to put you to sleep and to follow on with anaesthetic gases to continue the anaesthetic. You must be able to breathe during the anaesthetic, so often a tube of some sort will be placed in your mouth. This may be a simple piece of curved hollow plastic called an "oral airway", or a more complicated tube such as a "laryngeal mask airway" or an "endotracheal tube". For some operations, muscle relaxants are required to paralyse the patient during surgery. Often, a powerful analgesic (pain killer) will be added to the mixture. This depends on the type of anaesthetic. Short acting drugs simply wear off. Anaesthetic gases are replaced by air or oxygen. Muscle relaxants, and sometimes the powerful pain killers, may need special drugs to reverse their effects. Once you are sufficiently awake, any tube in your mouth can be removed. You will stay in the Recovery Room for an hour or two until you are completely awake. You should remember not to operate machinery or drive a car for 24 hours after your anaesthetic. Modern anaesthetics are extremely safe. Thanks to the excellent modern monitors, better drugs, and the training of modern anaesthetists, anaesthesia is getting safer all the time. For healthy patients, anaesthesia is so safe that it is difficult to measure the degree of risk any more. People with serious heart, lung or other disease, obviously, have an increased risk.
Accidents can still happen, but modern monitors usually ensure that any problems are picked up at an early stage. Older and sicker patients now undergo surgery, but with care, and perhaps with a few days in an Intensive Care Unit, most of them can be got through even major surgery.
- Stop smoking.
- Smoking has been recognised as a cause of postoperative breathing problems since 1944. If you can stop smoking for a few hours, you will be able to eliminate the poisons carbon monoxide and nicotine from your bloodstream. However, it takes between one week and six months for your lungs to show improvement, and your ability to fight infection will remain below normal for one to six weeks. If you need surgery, you should stop smoking NOW.
- If overweight, lose weight
- Obese patients pose many problems to the anaesthetist, and are more likely to run into breathing problems.
- Have a Check-Up
- Your surgeon or hospital will probably require this anyway.
- Take your medications
- In general, if you need medications, especially for serious conditions such as high blood pressure, angina or asthma, you should continue to take them on the day of surgery, with a sip of water. Your doctor will give you specific advice about any medicine for diabetes, and may ask you to stop taking anti-inflammatory drugs such as aspirin or ibuprofen, for a week before surgery.
- Obey the "Nil by Mouth" Rule
- Many hospitals now allow nothing by mouth for six hours before surgery, except that clear fluids may be taken up to three hours before surgery. Check with your doctor, and do as you are advised. Having an anaesthetic with food and acid still in your stomach may be dangerous.
- Make sure your anaesthetist knows about your problems
- The anaesthetist will probably have reviewed your chart. Nevertheless, a reminder about allergies to medication, serious illnesses, previous problems with anaesthetics and about loose teeth would be wise.
Disalin dari : © John Oyston, 1995
Individual copies may be made for personal use. For multiple copying or commercial use, or to suggest subjects for this section, please contact Dr. Oyston by sending an e-mail to
(This was originally on the Orillia Soldiers' Memorial Hospital Department of Anesthesia page)
A Guide to Spinal Anaesthesia for Caesarean Section
for Anaesthetists and Anesthesiologistsby Dr. John Oyston MB BS, FFARCS.
This was written in 1996. Since then, I have reduced my doses to 1.25 ml 0.75% Bupivacaine for everyone and 0.2mg of epimorph. Others have reduced the dose even further. The advantages of lower doses are less hypotension and less itching. How low can you go? See a comment at the end.
Why Spinal Anaesthesia for Caesarean Section? I was taught to use general or epidural anaesthesia for Caesarean section. After reading an article by Brownridge I wanted to try using spinals, but the technique was out of favour. There were concerns about historical medico-legal problems, hypotension and post-dural puncture headache. I finished my training (C.V.) in Toronto in 1990 without ever seeing a Caesarean section under spinal anaesthesia. Once I obtained a staff position, I decided I had to learn the technique so that I would have it in my bag of tricks for the "Urgent C-Section / Difficult Intubation" case I figured I would eventually come across. I read what I could find, then taught myself a way to do the block. It worked better than I dreamed possible. Compared to an epidural, a spinal:
- is quicker and possibly cheaper (Riley)
- is easier
- is less painful
- uses a lower dose of local anaesthetic
- and produces a denser block!
Spinals have become the anaesthetic of choice for Caesarean section in the major Canadian teaching centres. However, when I did a survey in the fall of 1994, 52% of Ontario hospitals were not using spinals for Caesarean section (Oyston). I hope that this article will encourage more anaesthetists to use the technique.
I used to worry about a list including a Caesarean section under epidural. I knew that the technique could occasionally be difficult, that the dose of drug necessary could cause life-threatening side effects, and that the quality of the block was often only just adequate, especially in anxious patients where additional intravenous situation is relatively contra-indicated by concern for the foetus. Now I look forward to doing these cases under spinal. A quick, easy block, using a small dose of local anaesthetic, will reliably produce an excellent block.
Patient Selection The following criteria must be met:
- Patient wishes to be awake.
- Standard contra-indications to epidural or spinal anaesthesia (local infection, coagulopathy, some types of severe cardiac disease, etc.) are absent.
- Section is not a true "emergency" section.
A spinal produces a more rapid onset of block, including a more rapid sympathetic block, which causes peripheral vasodilatation and hypotension which is frequently more severe than that associated with epidural anaesthesia. Care is needed in patients who are less able to tolerate this situation (e.g. pre-eclampsia, aortic stenosis, Eisenmengers' syndrome (Smedstad)). In these circumstances, the anaesthetic technique must be tailored to the individual case, and many would suggest that if the patient wishes to be awake, a slow gentle introduction of epidural anaesthesia, perhaps with invasive haemodynamic monitoring, is preferable to spinal anaesthesia, as it gives greater control. However, Wallace has shown that a combined spinal/epidural technique is safe in pre-eclampsia.
- Usual "Nil by Mouth" rules unless urgent.
- Explanation of procedure and consent.
- No sedative premedication.
- Oral antacid. I use Na Citrate 30ml p.o., but a regime of ranitidine and metoclopramide p.o. or i.v. may be better.
- Good I.V. access and fluid preload. Usually an #18 gauge intravenous is inserted but if the patient comes to the O.R. without an I.V., I frequently use a #16 gauge. It seems that no amount of preload can prevent hypotension in all cases , but a preload of 500 - 1,000 mls does help (Rout). It no longer seems essential to delay urgent surgery while waiting for the preload.
- Monitoring: At least a B.P. cuff and pulse oximeter during the block. As the E.C.G. wires tend to get in the way, I often check the E.C.G. then disconnect the monitor while doing the block and reconnect it after.
Performing the Block Check: Make sure that a working anaesthesia machine is available, complete with a method of ventilating the patient with oxygen, suction, intubation equipment, and standard anaesthetic and resuscitation drugs.
Have ephedrine drawn up. I make up a 10 ml syringe with 50 mg of ephedrine made up to 10 mls with saline.
Positioning: I prefer sitting up, with the patients' ankles at the foot of the bed, knees spread out, curved over a pillow or with her hands in front around her knees. A skilled assistant is a great help. Others use a lying position, usually right side down, as the patient will be tilted left side down during the surgery. However, even left side down can be used. Inglis showed that the sitting position is quicker, and that these patients require less ephedrine.
Prep and Drape: I put on a hat and mask, wash my hands and glove. I recommend a formal scrub and gown until one is quick at the procedure. The patient is prepped with povidone iodine and draped, using the Baxter Spinal Anesthesia Tray (Baxter Healthcare Corp., Deerfield, IL 60015 USA).
Drugs: I use 0.75% heavy bupivacaine 1.5 mls (11.25 mg) with 0.33 mls (0.33 mg) of preservative-free epidural morphine (1.0 mg per ml) for most cases, unless the patient is under 5 feet 4 inches tall, in which case I use 1.25 mls bupivacaine with 0.25 mls morphine. Morgan describes a range of alternative doses. Some people prefer a lower dose of morphine, or use fentanyl or sufentanil. Use a filter needle to draw up the drugs.
The Needle: I use a #27 gauge 3.5 inch (0.41 mm x 8.89 cm) Whitacre needle (Becton Dickinson and Company, Franklin Lakes, NJ 07417 USA). Use the smallest needle possible, and use a "tearing" rather than "cutting" tip. The 24 gauge Sprotte needle is acceptable (Mayer), but some find the long opening, set further back from the tip of the needle, a disadvantage. Most reports suggest a low incidence of spinal headache with 25 gauge needles, but I had three consecutive mild spinal headaches with my first three cases using 25 gauge Whitacre needles! I therefore changed to 27 gauge, and have had no further problems. I have a 98% success rate with this size of needle. Smith reported a 4% spinal headache rate and no failures with a 25G needle, and no spinal headaches but an 8% failure rate with 27G needles.
The Block: Identify the L3/4 interspace (or the one above or below, if easier). Infiltrate the skin with 1% lidocaine. I use a 21 gauge 1.5 inch (3.8 cm) needle to do this, then leave the needle in place to act as an introducer. This eliminates one needle prick. Using this needle, stay in the midline, pointing slightly towards the patient's head (roughly 80 to 85 degree angle to skin), and insert the needle almost to the hub in the average sized patient. Now, take the spinal needle and insert it through the introducer. This is easier if you let the needle rest on the lowest part of the inside of the rim of the introducer, which then stabilises it in the midline, so that you only have to get the position right in the vertical plane to enter the introducer needle's aperture. Push the spinal needle in slowly and gently. The "feel" is minimal, but often the denser ligamentum flavum and the "pop" as the arachnoid are pierced can be detected. With the needles I use, I usually find CSF after about 2.5 to 3 inches have been inserted into the introducer. It is rarely necessary to aspirate to get CSF. I attach the syringe, aspirate about 0.2 mls of CSF, inject about half the local anaesthetic, then aspirate, inject the rest, and aspirate again. If the aspiration test fails at any stage, I can at least estimate the amount of drug given, and add more to make up the estimated deficit.
Immediately after injecting, I put a small dressing on the puncture site and have the patient lie down with a wedge under the right hip.
Testing the Block If you give the right dose of the right drug into the right place, the block WILL work. Testing is hardly necessary, and I often omit it. However, testing has some uses, such as teaching the anaesthetist how much drug is needed, catching the rare block which is too high or too low before it becomes a problem, and reassuring the patient, the surgeon, and the anaesthetist!
I use an alcohol wipe to test. I ask the patient if it feels cold on her arm. Most say "Yes" but some cannot tell. I then wipe it up the abdomen, starting from the inguinal region and heading up to the nipple in mid-clavicular line, and ask the patient to tell me when it feels cold. If it never feels cold, I try on the shoulder. Most patients can say where the block has got to. If it is above the umbilicus at five minutes, I position the patient slightly head up. (The surgeons I work with all do Pfannensteil incisions.) This method is non-invasive and introduces the patient to the idea that one type of sensation (cold) can be blocked without another (touch). The block comes on more rapidly than surgeons can scrub, prep, drape, and catheterise the patient. Most surgeons will test by pinching the site of incision with a clamp. Patients are not usually aware of this happening.
Intra-operative Management Patients receive oxygen (2 litres per minute) by nasal prongs until delivery, when it is discontinued if all is stable.
Hypotension is a frequent problem. I sometimes give 10 mg ephedrine prophylactically, and sometimes add 10 mg to the IV bag. Others will give intramuscular ephedrine prophylactically, but this seems rather uncontrollable. At the first suggestion of nausea I give 10 mg ephedrine IV before even checking the blood pressure.
Very few patients require any additional sedation. Rarely, I will give 50% nitrous oxide by mask. Exceptionally anxious patients may need IV benzodiazepines, but most can be emotionally supported and persuaded to put up with any discomfort, at least until the baby is born. Supplemental narcotics should be avoided, as they increase the risk of postoperative respiratory depression.
Postoperative Orders This is our standard form:
[SPACE for PATIENT ID LABEL]
ORILLIA SOLDIERS' MEMORIAL HOSPITAL
EPIDURAL MORPHINE OBSTETRIC UNIT ROUTINE ORDERS
EPIDURAL MORPHINE OBSTETRIC UNIT ROUTINE ORDERS
Epidural/Spinal morphine .....mg was given at .......[TIME]
The following orders are in effect for 18 hours after bolus dose:
- To remain in recovery room until ......[TIME or "moving legs"]
- No IM or IV narcotics unless prescribed by anaesthesia..
- Close observation until 18 hours after bolus dose:
- Respiratory rate Q 1 H
- IV or PRN adapter in situ
- Naloxone ("Narcan") 0.4mg available
- If the patient is unduly drowsy or
If the respiratory rate is less than ten per minute:
Give naloxone 0.1mg (1/4 of ampoule) IV stat
Repeat Q 1 minute up to 0.4mg if needed
- For itching:
Benadryl [diphenhydramine] 50mg IM or PO (one dose)
If this fails, give naloxone 0.04mg (1/10th ampoule) IV Q 10 mins PRN
(Dilute one ampoule with 9mls saline, give 1-10mls)
- For nausea and vomiting:
Gravol [dimenhydrinate] 25mg IM or IV PRN Q 15 mins (Max 100mg)
- For urinary retention:
"In & out" catheter
- Tylenol #3 [acetaminophen 300mg with codeine 30mg] 1-2 tabs Q 4 hr PRN
- Benadryl 50mg PO Q 4 H PRN x 24 hours
Conclusion Spinal anaesthesia is an excellent technique for Caesarean section. It has become the routine in Canadian teaching centres, and deserves to be used even more widely in community hospitals.
All obstetric anaesthetists should learn the technique.
| Dr Kari Smedstad (Chief of Obstetrical Anaesthesia, McMaster University, Hamilton, ON) and
Dr Pamela Morgan (Director of Obstetrical Anaesthesia, Mt Sinai Hospital, Toronto, ON)
kindly provided useful suggestions which substantially improved this article.
The opinions expressed in this document are the author's personal opinions.
ABOUT THE AUTHOR
Dr John Oyston, MB BS, FFARCS, is a certified specialist anaesthetist, currently working in the Anaesthesia Department of The Scarborough Hospital, in Ontario, Canada. He can be reached by e-mail to.
Tinitus merupakan suatu gangguan pendengaran berupa keluhan perasaan pada saat mendengarkan bunyi tanpa ada rangsangan bunyi atau suara dari luar. Adapun keluhan yang dialami ini seperti bunyi mendengung, mendesis, menderu, atau berbagai variasi bunyi yang lain.
Tinitus ada 2 macam yang terbagi atas tinitus obyektif dan tinitus subjektif. Tinitus obyektif terjadi apabila bunyi tersebut dapat juga didengar oleh pemeriksa atau dapat juga dengan auskultasi di sekitar telinga. Sifatnya adalah vibritorik yang berasal dari vibrasi atau getaran sistem muskuler (otot) atau kardiovaskuler di sekitar telinga. Sedangkan tinitus subjektif terjadi apabila suara hanya terdengar oleh pasien sendiri, dan jenis tinitus ini yang paling sering terjadi. Sifat dari tinitus subjektif adalah nonvibratorik karena adanya proses iritatif ataupun perubahan degenaratif pada traktus auditorius yang dimulai dari sel-sel rambut getar koklea sampai pada pusat saraf dari pendengar.
Mekanisme terjadinya tinitus karena aktifitas elektrik di sekitar auditorius yang menimbulkan perasaan adanya bunyi, tetapi impuls yang terjadi bukan berasal dari bunyi eksternal atau dari luar yang ditransformasikan, melainkan berasal dari sumber impuls yang abnormal di dalam tubuh penderita sendiri.
Impuls abnormal itu dapat ditimbulkan oleh berbagai kelainan telinga. Tinitus dapat terjadi dalam berbagai intensitas. Tinitus dengan nada rendah, seperti bergemuruh atau nada tinggi, seperti berdengung. Tinitus dapat terus menerus atau hilang timbul terdengar.
Tinitus biasanya dihubungkan dengan tuli sensorineural dan dapat juga terjadi karena gangguan konduksi. Tinitus yang disebabkan oleh gangguan konduksi, biasanya berupa bunyi dengan nada rendah. Jika disertai dengan inflamasi, bunyi dengung ini terasa berdenyut (tinitus pulsasi).
Tinitus dengan nada rendah dan terdapat gangguan konduksi, biasanya terjadi pada sumbatan liang telinga karena serumen atau tumor, tuba katar, otitis media, otosklerosis, dan lain-lain.
Tinitus dengan nada rendah yang berpulsasi tanpa gangguan pendengaran merupakan gejala dini yang penting pada tumor glomus jugulare.
Tinitus objektif sering ditimbulkan oleh gangguan vaskuler. Bunyinya seirama dengan denyut nadi, misalnya pada aneurisma dan aterosklerosis. Gangguan mekanis dapat juga mengakibatkan tinitus objektif, seperti tuba Eustachius terbuka, sehingga ketika bernapas membran timpani bergerak dan terjadi tinitus.
Kejang klonus muskulus tensor timpani dan muskulus stapedius, serta otot-otot palatum dapat menimbulkan tinitus objektif.
Bila ada gangguan vaskuler di telinga tengah, seperti tumor karotis (carotid-body tumour), maka suara aliran darah akan mengakibatkan tinitus juga.
Pada tuli sensorineural, biasanya timbul tinitus subjektif nada tinggi (sekitar 4000Hz)
Pada intoksikasi obat seperti salisilat, kina, streptomysin, dehidro-streptomysin, garamysin, digitalis, kanamysin, dapat terjadi tinitus nada tinggi, terus menerus atau hilang timbul.
Pada hipertensi endolimfatik seperti penyakit Meniere dapat terjadi tinitus pada nada rendah dan tinggi, sehingga terdengar bergemuruh atau berdengung. Gangguan ini disertai dengan tuli sensorineural dan vertigo.Gangguan vaskuler koklea terminalis yang terjadi pada pasien yang stres akibat gangguan keseimbangan endokrin, seperti menjelang menstruasi, hipometabolisme atau saat hamil dapat juga timbul tinitus atau gangguan tersebut akan hilang bila keadaannya sudah kembali normal.
Tinitus merupakan suatu gejala klinik penyakit telinga, sehingga untuk pengobatannya perlu ditegakkatn diagnosis untuk mencari penyebabnya yang biasanya sulit untuk diketahui. Anamnesis merupakan hal yang utama dan sangat penting dalam penegakkan diagnosis tinitus. Perlu ditanyakan kualitas dan kuantitas tinitus, adanya gejala lain yang menyertai, misalnya adanya vertigo dan atau gangguan pendengaran serta gejala neurologik lain, riwayat terjadinya tinitus unilateral atau bilateral, apakh sampai mengganggu aktivitas sehari-hari. Pemeriksaan fisik THT dan otoskopi harus secara rutin dilakukan, pemeriksaan penala, audiometri tutur, bila perlu dilakukan pemeriksaan BERA dan atau ENG serta pemeriksaan laboratorium.
Beberapa hal yang perlu diperhatikan dalam anamnesis adalah : lama serangan tinitus, bila berlangsung dalam waktu 1 menit biasanya akan hilang sendiri, hal ini bukan keadaan patologik. Bila berlangsung dalam 5 menit merupakan keadaan patologik. Tinitus subjektif unilateral disertai gangguan pendengaran perlu dicurigai kemungkinan tumor neuroma akustik atau trauma kepala. Bila tinitus bilateral kemungkinan terjadi pada intoksikasi obat, presbiakusis, trauma bising, dan penyakit sistemik lain. Apabila pasien sulit mengidentifikasi kanan atau kiri kemungkinannya disaraf pusat. Kualitas tinitus, bila tinitus bernada tinggi biasanya kelainannya pada daerah basal koklea, saraf pendengar perifer dan sentral. Tinitus bernada rendah seperti gemuruh ombak khas untuk kelainan koklea seperti hidrops endolimfa.
Pengobatan tinitus merupakan masalah yang kompleks dan merupakan fenomena psikoakustik murni, sehingga tidak dapat diukur.
Perlu diketahinya penyebab tinitus agar dapat diobati sesuai dengan penyebabnya. Kadang-kadang penyebabnya itu sukar diketahui.
Pada umumnya pengobatan gejala tinitus dapat dibagi dalam 4 cara yaitu :
- Elektrofisiologik yaitu dengan membuat stimulus elektro akustik dengan intensitas suara yang lebih keras dari tinitusnya, dapat dengan alat bantu dengar atau tinitus masker.
- Psikologik, dengan memberikan konsultasi psikologik untuk meyakinkan pasien bahwa penyakitnya tidak membahayakan dan dengan mengajarkan relaksasi setiap hari.
- Terapi medikamentosa, sampai saat ini belum ada kesepakatan yang jelas diantaranya untuk meningkatkan aliran darah koklea, tranquilizer, antidepresan, sedatif, neurotonik, vitamin, dan mineral.
- Tindakan bedah dilakukan pada tinitus yang telah terbukti disebabkan oleh akustik neuroma.Pasien yang menderita gangguan ini perlu diberikan penjelasan yang baik, sehingga rasa takut tidak memperberat keluhan tersebut.
Obat penenang atau obat tidur dapat diberikan saat menjelang tidur pada pasien yang tidurnya sangat terganggu oleh tinitus itu. Kepada pasien harus dijelaskan bahwa gangguan itu sukar diobati dan dianjurkan agar beradaptasi dengan gangguan tersebut.