POSTOPERATIVE VOMITING: A REVIEW ~ND ~?RESENT STATUS OF TREATMENT* L. E. SI2vlONSEN, M.D., C.NI., and S. L. VANDEWAjTER,M.D., r.R.c.r. (c.) t POSTOPERATIVE VO~vlITING remains one of the most I frequent complications en- countered by the anaesthetist. Although considered no|more than a nuisance complication, it can, in certain cases, contribute to more ~lSan just discomfort for the patient; it can threaten his very life either immediately through aspiration, or later by serious loss bf fluids and electrolytes. It cap also add considerable strain on some operation wounds. After Wang and Boxison 1 further delineated the vomit ng centre in 1952, most of the succeeding research and investigation into the ~ontrol of vomiting has centred about those drugs that have a depressant actio 1 on the chemoreceptor trigger zone (C.T.Z.). Out of these investigations have c ~me much valuable and interesting data which the anaesthetist may use as additio ns to his ever-expanding resources to provide safety and comfort to the surgical patient. THE VOMXTn~OCENTaE Neurophysiologists have long accepted the existence of a vomiting centre. Located in the medulla in the solitary tract and the dgrsal part of the lateral reticular formation, it lies in close relationship to ma:ay other centres whose functions are associated with the vomiting act such ts salivation, spasmodic respiratory movements, and forced inspiration. ~ Lying lorsolateral to the vagal nuclei and close to the vomiting centre in the area pos :rema of thefloor of the fourth ventricle is an accessory vomiting centre which Ihas been designated as the C.T.Z. The C.T.Z. is a receptor centre, the functio~ of which is to act as a funnel for many afferents arriving centrally from lower levels and to channel these stimuli to the emetic centre which co-ordinates aUthe nervous and chemical stimuli that converge on it. The C.T.Z. is not a relay for all afferents, however, since those stimuli which originate in the autonomic nerve endings of the gut, ~ kidneys, uterus, or the heart4 travel via the vagus nerve or sympathetic nervous isystem, or both, reaching the vomiting centre directly without traversing the C.T.~. Other stimuli affecting the vomiting centre directly are those arising from (a) hypoxia of.-the centre, as for example from increased cerebrospinal fluid pressure, or (b) psychic stimuli from the cerebral cortex. The pathways and ori g in of stimuli causin g vomitin ~ ma y be summarized as in Table I. It seems reasonable, therefore, that pharmacological efforts to con- trot nausea and vomiting might well be directed at interrupting one of these reflex arcs. *Presented at the Annual Meeting of the Canadian Anaesthetists' Society, Montebello, P.Q., May 8--11, 1961. Wrom the Department of Anaesthesia, Queen's University, Kingston, Ontario. 51 Can. Anaes. Soc. J., vol. 9, no. 1, January, 1962 52 CANADIAN ANAESTHETISTS"SOCIETY JOUBNAL TAI}LE ][ CAUSES OF VOMITING i 1. Indirectly via C.T.Z. (a) Blood-borne chemical stimuli (b) Vestibular stimuli ( motion sickgess ) (c) Certain metabolic and endocrin 9 stimuli producing vomiting of pregnancy 2. Directly via vomiting centre (a) Stimuli arising from the wall of the g~t or heart (b) Hypoxia of the centre-increased inttacranial pressure, anaemia, anoxaemia as in high altitudes (c) Psychic stimuli-pain, smell, taste, sight INCIDENCE AND FACTORS RELA?FED TO POSTOPERATIVE VOMITING Severa~ extensive series of investigations into the incidence~f postoperative nausea and vomiting have been reported. The wide range of ~sults reflect the magnitude of the variations of techniqge, agents used, ability of the anaesthetist, and dependability of the observer. Waters ~ in 1936, in a series of 10,000 cases, reported an over-all incidence of 40.6 per cent. In 1955, Dent 6 found a_~nincidence of 27.2 per cent land Burt'es and Peckett 7 an incidence of 32 per cent. iThese investigations include all types of surgery and anaesthetic techniques. ~control series by Gordon et al. s in 1954 reported an over-all incidence of 41 per cent. Knapp and Beecher ~ in 1956, using a standard sequence of nitrous oxidel oxygen, and ether for various types of operations, found an incidence as high as 82 per cent whereas Dobkin's 1~ over-alt incidence, excluding those with gastri6 suction, was only 15.5 per cent. Factors relating to postoperative ndusea and vomiting are many and varied. In an excellent review by Belleville, 11 the most consistent factor noted was the sex difference; women vomited much more ,commonly than men with no decrease in the female incidence until the eighth decade of life. Men, on the other hand, had a decreasing incidence with age./Boni~bal~ felt that the age group 40 to 60 had the highest incidence. When morphine is used as a premedicant, there is a higher incidence noted than with meperidine. TM The incidenVe of nausea and :~hme~nL dPlPoT::t t:mbo:g~gh::thm ~ e ~h: st~i o~h: t :~la~: n :~:~~ eolxi~ and thiopentone. Because of,the decr/ased probability of forcing irritating gases into the stomach, those patients who l are intubated vomit less,' than those who receive their anaesthetic by mask. 6,11,1a Hypotension during surgery increases the incidence, possibly owing to anoxaemla of the vomiting eentretll The incidence is also directly proportional to th6 length of anaesthesiaT.~,~2,~*; but Belleville, ~ on the other hand, felt that the ~eidenee decreased in proportion to the length of postoperative sleeping time. Robbie in found that operationsf lasting less than half an hour or longer than one hour were followed by a lower incidence than operations lasting between one-half and one hour. The same author felt that with breast operations there was a higher; ineJ[denee than with operations at ~other sites. Dent, 6 however, found that more persons having head ~nd neck surgery vomited than those having intra-abdominal or extra-abdominal operations. IThis ,SI~IONSEN & VANDEWATER: POSTOPERATIVE VQMITING 53 / can be expected since the solitary tract that receive~aff~rents from the facial, od~176 eal,g and vagu s nerves is also the site of the vomitin, g centre. Burtles and Peckett 7 have shown that the Trendelenbttrg ,~r reyersed Trendelenburg positions were associated with a higher incidence 'lprol~ably because a large proportion of operations! in these positions are carried Out in the female, for example, gTnaecological abdominal surgery, varicose veir~ surgery, thyroideeto- mies and mastectomies." The ]owest vomiting inciderme ~as associated with the lithotomyposition. CAUSES OF POSTOPERATIVE VO~'I~TING0i I / 1. Circulating anaesthbtic a~ents or break-down product~., 2. Hypoxia-o~f the vo~niting centre from any catrse such as hypotension or increased intracranial pressure. 3. Psychogenic or cortical, including odours, sights, taste I. 4. Gastric irritants, e.g., anaesthetic vapors. f .5. Distention or traction of viscera from surgical ma!nipulation. 6. Movements of the patient's head (motion sickness ). 7. Emergency patient with a full stomach. 8. Stimulation of vagus, glassopharyngeal, or facial neryes from surgery in the vicinity of {hese nerves. 9. Idiopathic or undetermined factors: (a) position dlaring surgery, (b) site of surgery, e.g., breast, pelvis, (c) sex and age. Tim ROLE Or THE ANTI-EMETICS In a review of the existing literature of the past decade or so, it appears that most of the investigation into postoperative nausea and vomiting centres about the anti-emetic properties of the antihistamines, phenothiazine derivatives, and other unrelated compounds such as trimethoxybenzamide. / However, a very old drug with anti-emetic properties ig one which tends to be lost in the myriad of new compounds: scopolamine. H C---- C------ CHe CHi20H /l 1 I I/----~ 0 I N-CHa CH.O.CO.C, k k \I t I ----; H C C---- CH., Scopolamine The antinauseant property of scopolamine has beet~ appreciated for many years although the site of action has not been clarified. Its ability to block impulses from the cortex to the medulla 16 helps support Goodman and Gillman's !7 opinion that scopolamine's site of action in motion sickness protection is likely cortical or directly on the utricular maculae. It may also be assumed that part of its anti-emetic efficacy may lie in its ability to block vagal impulses to the vomiting centre from the bowel and heart. Because~0 f the number of other antinauseants in common use, and also because of ~e undesirable side effects 54 CANADIAN ANAESTHEtiSTS' SOCIETY JOUtlNAL of the drug such as drowsiness, tachyCardla, , and vasual disturb. 9n ees m lar er doses, it perhaps is not the drug of c~aOiee m the prevention or treatment!of nausea and vomiting. When antihistamines were discpverr (by accident)to havre antinause~t properties, numerous investigationsl Wer~ carried out on a varie~ of these drugs: Those found to be most useful Wer~' dimenl~ydrmate" (Dramamine)," ' " i8,i9,~i if!: diphenhydramine (Benadryl),Z".2a ~nd ~yclizine lactate (Marzine ,.12,!8,~4,~5O@er antihistaminics such as propherlpyri'i~tamine i(or Trimeton)i chlorcycli~ (Perazil), and meclizine (Bonami~e) are also listed 6 as g~wng s~gnifieant pr0,1 tection against motion sickness as ~omFared With a placebo but~ not of sufflci'nt imp~ta~ace to elaborate upon in a reviev of this nature. } ,,I ! 0 0 N , , CHo. CH~ () I 1 N CH_~ CH,., / ~ I t H C~ N N ,/ "N, /" ~ Cyclizine lalctatef CH3 CH3 Clt3 CH3 Diphenhydramine ( CH 3--( //\I o ? CH~ Dime~hydrillate Although dimenhydrina~,.differs from diphenhydramine by the additioo 0f 8-chlorotheophylline, the radi'cal contributes, nothing to the antitemetie a.ctio~I ~0f the drug and the two drugs are considered equal in effect.