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15. Anaesthesia and Obstetrics
- Hong Kong University Press, HKU
- Chapter
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15. Anaesthesia and Obstetrics During the anaesthetic management o f obstetrical patients , one must b e mindful o f the fact that two lives are involved, the mother and the baby. There are basically two periods whe n anaesthesi a (o r analgesia ) ar e required . Th e first on e i s when dealin g with ordinary labour and deliver y pains, th e second one is during operative delivery, such a s forceps, version s and caesarea n sections , and possibl y repai r o f episiotom y wounds or perineal tears. Pain relief, while as effective a s possible, must not interfere with the well-being and safety of the mother and the child. Uterine activity should not be impaired, so as not to prolon g th e cours e o f labou r o r eve n increas e th e hazard s fo r th e child . Ther e should b e n o excessiv e drowsines s o r depressio n (respirator y o r cardiovascular ) o f the mother an d baby . Whe n genera l anaesthesi a i s used, immaculat e car e mus t b e exercised agains t th e wel l recognize d hazard s o f vomitin g o r regurgitatio n o f stomach content s an d thei r subsequen t inhalatio n int o th e laryn x o r tracheobron chial tree. This danger is still very high. Cases, even fatal, of Mendelson's syndrom e are still occurring. An additional factor which must be considered is that all agents at our disposa l i n anaesthetic practice today d o cros s the placenta i n varying degrees . The baby is therefore liabl e to be affected b y these substances. Pain relief in labour shoul d alread y b e considere d i n th e antenata l period . A sympathetic and understanding doctor or midwife, by simple but thorough explana tion of all that is involved in childbirth, can do a lot in allaying the patient's fears and anxieties. The expectant mother shoul d be told that there are ways and means , with her cooperation , t o minimiz e pain , an d pai n i s no t necessaril y a majo r featur e i n childbirth. Thi s is particularly tru e in primigravidae. On e shoul d als o bear i n min d that th e pai n threshol d varie s i n differen t individual s an d i n differen t nationalities . Some mothers have been led to believe (specially in certain countries) that the louder they cry during childbirth , the healthier will be their babies. Antenatal exercise s ar e also useful, a s when properly taught and carried out, women are able to relax better, both mentally and physically . Once labou r ha s started , th e mothe r shoul d no t b e give n an y soli d food , an d antacids (suc h a s Mist . Magnesiu m Trisilicat e 10-2 0 ml , 2 hourly) shoul d b e ad ministered (s o a s to kee p the mother's gastri c pH abov e th e critica l leve l o f 2.5 , in case genera l anaesthesi a ma y becom e necessar y a t shor t notice) . Som e authoritie s believe that cimetidin e ( a blocker o f H2 receptor s in the parietal cell s of the gastri c mucosa) may als o be useful i n this respect, because the acidity and volume of bot h basal and nocturnal gastric secretions, and those secretions produced by most known 274 Anaesthesia and Other Specialties stimuli to aci d productio n ar e considerabl y reduce d b y this substance. I n addition , both th e maximal aci d output (MAO ) and th e peak aci d output (PAO ) are likewis e considerably reduced . Malagelad a an d Corto t (1978) , an d Dob b (1978 ) hav e re viewed th e valu e o f cimetidin e i n th e preventio n o f aci d aspiratio n syndrom e an d Husemeyer, et al (1978 ) hav e reporte d o n th e effectivenes s o f a singl e ora l dos e for prophylaxis . Th e rol e o f cimetidin e ha s bee n furthe r examine d i n...