EFFECT OF ANXIETY ON GASTRIC EMPTYING IN PREOPERATIVE PATIENTS

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1 Br. J. Anaesth. (1987), 59, EFFECT OF ANXIETY ON GASTRIC EMPTYING IN PREOPERATIVE PATIENTS K. H. SIMPSON AND A. F. STAKES Pulmonary aspiration of gastric contents remains an important cause of anaesthetic mortality and morbidity (Lunn and Mushin, 1982), and many studies have demonstrated the presence of large volumes of acid stomach contents in patients prepared for surgery. For example, Hester and Heath (1977) recovered more than 40 ml of fluid from the stomach of one in eight patients presenting for elective surgery despite prolonged fasting. In over half the patients, the ph of the gastric contents was less than 2.5. More than 25 ml of acidic stomach fluid was aspirated from 66 % of patients presenting for minor outpatient operations (Ong, Palahniuk and dimming, 1978). It has been suggested that pain and anxiety cause gastric stasis, but few studies have attempted to differentiate these factors. However, it is known that trauma to the extremeties in the dog, and cold stress in man, may reduce gastric motility (Zaricznyj et al., 1977; Thompson, Richelson and Malagelada, 1982). In 1983 Marsh, Spencer and Nimmo measured gastric emptying in 10 patients 2-3 h before elective surgery, and again 2-5 days later, to assess the effect of preoperative anxiety. As there was no difference in paracetamol absorption on the two occasions, it was concluded that anxiety had no effect on gastric emptying, although anxiety was not quantified as it was assumed to be present in all preoperative patients. When studying anxiety it is important to distinguish between temporary emotional states and stable personality dispositions. Cattel and Scheier (1958) applied multivariate factor analysis techniques to the definition and measurement of anxiety; state and trait anxiety consistently emerged as principal personality dimensions. Anxiety state increased in stressful situations, and K. H. SIMPSON, M.B., CH.B, F.F.A.ILCJ.; A. F. STAKES, M.B., B.S., F.F.A.R.C.S.; University Department of Anaesthesia, Clinical Sciences Building, St James's University Hospital, Leeds LS9 7TF. Accepted for Publication: October 14, Correspondence to K.H.S. SUMMARY On the morning of operation 30 patients awaiting minor gynaecological surgery completed a Spielberger State Trait Anxiety Inventory. Gastric emptying was then measured using paracetamol absorption. Anxiety State scores, which reflected situational anxiety, were unrelated to Anxiety Trait scores, which assessed anxiety proneness. Paracetamol absorption was reduced and delayed in patients with low anxiety trait who developed high anxiety state before surgery, compared with patients whose anxiety state scores were lower than, or similar to, their anxiety trait scores. Therefore, it was concluded that gastric stasis occurred in patients with a low predisposition to anxiety who became apprehensive whilst awaiting surgery. was denned as "a transitory emotional condition or feeling, characterised by subjective, consciously perceived tension and apprehension with heightened autonomic nervous system activity ". Anxiety trait is anxiety proneness, denned as "a stable long range predisposition to respond to stress with anxiety, and the tendency to perceive a wide variety of situations as threatening". In 1970, Spielberger, Gorsuch and Lushene developed the State Trait Anxiety Inventory to provide a reliable, brief, self-reporting questionnaire to measure both facets of anxiety. The anxiety state scale increased in response to various kinds of stress and decreased after training in techniques promoting relaxation (Spielberger, 1975). It correlated well with other measures of situational anxiety such as the Multiple Affect Adjective Checklist (Zuckerman, 1960). The anxiety trait scale correlated with other measures of anxiety predisposition such as the Taylor Manifest Anxiety Scale (Taylor, 1953) or the Institute for Personality and Ability Testing (IPAT) scale (Cattel and Scheier, 1958).

2 PREOPERATIVE ANXIETY AND GASTRIC EMPTYING 541 Johnston (1980) used the Spielberger questionnaire to study the natural course of perioperative apprehension and showed that anxiety was not restricted to the immediate preoperative period; only a small proportion of patients reached maximum anxiety on the day of surgery. The present study was designed to measure preoperative anxiety and anxiety proneness, as well as gastric emptying. PATIENTS AND METHODS On the morning of operation 30 fit patients awaiting minor gynaecological surgery completed a Spielberger State Trait Anxiety Inventory, which gave a numerical score, out of 80, for anxiety state and trait. Gastric emptying was then measured using a paracetamol absorption technique similar to that described by Heading and colleagues in After a fast of at least 4 h an indwelling i.v. cannula was sited in a forearm vein under local anaesthesia. Paracetamol 1.5 g with 150 ml of water was given by mouth. Patients remained supine for 2 h whilst blood was sampled at intervals; plasma was frozen at 20 C for paracetamol assay as a batch. Paracetamol was measured using an enzymatic assay method, specific for the parent compound, which did not detect paracetamol metabolites (Cambridge Life Sciences). The enzyme aryl acylamide amidohydrolase was used to split the amide bond of paracetamol, producing acetate and p-aminophenol. The latter reacted with o-cresol to form a stable blue compound which was measured using a spectrophotometer capable of reading at 615 nm. The procedure was automated to improve the performance of the assay at the low concentrations of paracetamol expected. The area under the plasma paracetamol concentration-time curve was calculated using the trapeziodal rule. Data were analysed using Pearson's Product Moment Correlation Coefficient, multiple regression analysis, Student's t test or one-way analysis of variance for independent samples. RESULTS The anxiety state and anxiety trait scores of the 30 women were not significantly correlated (r = 0.31, t = 1.75). Multiple regression analysis showed that gastric emptying was delayed in patients with a low anxiety trait who developed a high anxiety state, compared with those whose anxiety state was lower than, or similar to, their anxiety trait. To give a numerical value for the level of preoperative apprehension relative to anxiety predisposition, each patient's anxiety trait score 80 I 3 8 uc o "n start* * Anxiety state -Anxiety trait FIG. 1. Relationship between peak plasma paracetamol concentrations and difference between anxiety state and anxiety trait scores (AS-AT). Regression equation: y = x; r = -0.61; t <= 4.07; P <

3 542 BRITISH JOURNAL OF ANAESTHESIA was subtracted from their anxiety state score. Linear regression of peak plasma paracetamol concentration against the difference between the anxiety scores demonstrated a significant relationship (P < 0.005). Peak paracetamol concentrations decreased as anxiety state increased relative to anxiety trait (fig. 1). Patients were grouped according to the relationship between anxiety state and anxiety trait scores. In 16 patients anxiety state was less than or equal TABLE I. Age, weight and duration of fasting in the two groups (Anxiety State = AS; Anxiety Trail = AT) AS «AT(n= 16) AS > AT (n = 14) Age (yr) Weight (kg) Starved (h) to anxiety trait, and in 14 patients anxiety state was greater than anxiety trait. The ages, weights and duration of fasting in the two groups were not significantly different (table I). plasma paracetamol concentrations were significantly lower at 15, 30 (P < 0.01), 45 and 60 (P < 0.05) min in patients with a low anxiety trait who developed a high anxiety state before surgery (fig. 2). These patients also had significantly TABLE II. Peak plasma paracetamol concentrations and time to peak (Anxiety State = AS; Anxiety Trait = AT) * P < AS <AT(n= 16) AS > AT (n = 14) Peak paracetamol concentration (jig ml" 1 ) * 1.8 Time to peak (min) * 8.0 reduced and delayed peak paracetamol concentrations (P < 0.005) (table II). Patients with a high anxiety state relative to anxiety trait had a smaller area under the plasma paracetamol concentration-time curve during the first 1 h, and over the 2 h of the study (P < 0.005) (fig. 3). DISCUSSION The use of the Spielberger State Trait Anxiety Inventory permitted evaluation of situational anxiety and anxiety predisposition in patients awaiting surgery. The finding that anxiety trait was not predictive of preoperative anxiety state was in agreement with previous work. It has been shown that stressful situations of an egothreatening nature evoke greater increase in anxiety state in subjects with a high anxiety trait 30-1,20 c o g i 10- e Time (min) FIG. 2. plasma paracetamol concentration at each time. Anxiety state = AS; anxiety trait *» AT. **P< 0.01; *P< 0.05.

4 PREOPERATIVE ANXIETY AND GASTRIC EMPTYING 543 AS<AT AS>AT ^ D o Time (h) FIG. 3. The area under the plasma paracetamol concentration-time curve (AUC), over 1 and 2 h. Anxiety state = AS; anxiety trait = AT. *P < (Auerbach, 1973a). However, in circumstances involving physical danger, including surgery, the magnitude of the change in anxiety state is unrelated to anxiety trait (Johnson, Dabbs and Leventhal, 1970; Auerbach, 1973b; Spielberger et al., 1973). Heading and colleagues (1973) showed a significant negative correlation between the halftime of gastric emptying and peak plasma paracetamol concentrations (r = 0.77). Therefore, the decrease in peak paracetamol concentrations seen in patients with high anxiety state, relative to anxiety trait, represented a delay in gastric emptying. The smaller area under the plasma paracetamol concentration time curve in these patients reflected a slowing of paracetamol absorption. Therefore, gastric stasis was demonstrated in patients who had a low predisposition to anxiety who became very anxious in the preoperative period. Patients with high anxiety proneness did not show any delay in gastric emptying, whatever their anxiety state score. These subjects may have been tolerant of frequent high levels of anxiety. Perhaps gastric motility was altered by neural or endocrine mechanisms in the anxious patients. The beta-adrenergic system has been shown to exert an inhibitory action on gastric emptying in normal circumstances (Rees et al., 1978); isoprenaline decreases and propranolol increases stomach emptying (Clark et al., 1980). Corticosteroids and adrenaline, in physiological concentrations, increase the amount of acidity of gastric secretions (Gray et al., 1951; Chaikof et al., 1961; Christensen and Stadil, 1976). The role of endocrine factors on changes in gastric motility in anxious patients merits further study. ACKNOWLEDGEMENTS The authors are very grateful to the staff of the Department of Chemical Pathology, St James's University Hospital, Leeds: Dr Evans (Top Grade Biochemist) and Mr Altren (Senior Chief MLSO) for advice and encouragement during the study, and Mr Smith (Chief MLSO) and Mr MaUinson (Chief MLSO) for excellent technical assistance and development of the automated paracetamol assay from the Cambridge Life Sciences kit. The authors thank Mr D. R. Bromham and Mr G. J. Jarvis (Consultant Gynaecologists) for access to patients during this study. REFERENCES Auerbach, S. M. (1973a). Effects of orienting instructions, feedback-information, and trait-anxiety level on stateanxiety. Psychol. Rep., 33, 779. (1973b). Emotional reactions to surgery. J. Consult. Clin. Psychol., 40, 264. Cattel, R. B., and Scheier, I. H. (1958). The nature of anxiety: a review of thirteen multivariate analyses comprising 814 variables. Psychol. Rep., 4, 351. Chaikof, L., Janke, W. H., Pesaros, P. C, Panka, J. L., and Brush, B. E. (1961). Effects of prednisone and corticotropin on gastric secretion. Arch. Surg., 83, 32.

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