Nausea and vomiting following thyroid and parathyroid surgery

ELSEVIER

Nausea and Vomiting Following Thyroid and Parathyroid Surgery James M. Sonner, MD,* James M. Hynson, Orlo Clark, MD,? Jeffrey A. Katz, MD$

MD,*

Department of Anesthesia, University of California, San Francisco School of Medicine; and Department of Anesthesia, Mount Zion Medical Center, San Francisco, CA. Study Objectives: To determine the incidence of postoperative nausea and vomiting (POW} following thyroid and parathyroid surgery. To determine whether PONV is reduced when propofol is usedfor maintenance of anesthesia as compared to isoflurane and to evaluate the costs and resource consumption associated with these two anesthetic regimens. Design: Randomized, prospective study. Setting: University-affiliated hospital-a refemal center for endocrinologic surgery. Patients: 118 ASA physical status I and Ilpatients, aged 18 years and older, undergoing elective thyroid or parathyroid surgery. Interventions: Patients received either isoflurane (0.5 to 1.3 % end-tidal) orpropofol(50 to 200 pg/kg/min) for maintenance of anesthesia. All patients received propofol fm induction of anesthesia, succinylcholine or vecuronium, nitrous oxide, and fentanyl. Prophylactic antiemetics were not administered. Postoperative pain was treated with ketorolac, fentanyl, or acetaminophen. Measurements and Main Results: Signs and symptoms of nausea and vomiting were graded on a four point scale as 1 = no nausea; 2 = mild nausea; 3 = severe nausea; 4 = retching and/or vomiting. Grades 3 and 4 were grouped together as POW. The combined incidence of POiVV was 54 % over the 24-hour-postoperative evaluation period. PONV was significantly more common in patients receiving isoflurane than propofol for maintenance of anesthesia (64% vs. 44 %). In women (n = 87), the incidence of POW was significantly greater in those patients who received isoflurane than those who received propofol for maintenance (71% vs. 42%). However, in men (n = 31), there was no signaficant diffuence in POhW between anesthetic regimens (47% with isoflurane vs. 50 % with propofol). There were no daffences in the duration of stay in the postanesthesia care unit, time to discharge from the hospital, or local wound complications (hematomas) between groups, The use of propofol for maintenance of anesthesia was associated with an additional cost, relative to the isoflurane group, of $54.26 per patient. Conclusion: Patients undergoing thyroid or parathyroid surgery are at high risk for the development of POW. Propofol f or maintenance of anesthesia, although more expensive than isoflurane, reduces the rate of PONVin women. 0 1997 by Elsevier Science Inc. *Assistant Professor of Anesthesia tProfessor

and Chief of Surgery

Keywords:

Emesis; nausea and vomiting;

surgery: thyroid,

parathyroid.

$Professor of Clinical Anesthesia Address correspondence to Dr. Sonner at BOX 1610.05, UCSF/Mt. Zion, 1600 Divisadera Street, San Francisco, CA 94115, USA. Received for publication May 27, 1996; revised manuscript accepted for publication March 19, 1997.

Introduction Nausea, with or without vomiting, occurs commonly after surgical procedures. In large series, postoperative nausea and vomiting (PONV) has been reported to occur in 20% to 70% of patients.’ POW is influenced by a variety of factors that involve the characteristics of the patients, surgery, and anesthesia.lW3 Recently, patients undergoing thyroidectomy have been shown to have a high rate of

Journal of Clinical Anesthesia 9:398-402, 1997 0 1997 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010

0952-8180/97/$17.00 PII SO952-8180(97)00069-X

Nausea afm

PONV.4 Similarly, at our institution, where approximately 200 thyroid and parathyroid surgeries are performed each year, we have noted PONV to be characteristically common following these procedures. Because patients typically have only mild-to-moderate pain after thyroid or parathyroid surgery, PONV may represent their principal source of discomfort, and it may be perceived as the most unpleasant aspect of postoperative recovery. Additionally, vomiting may increase the risk of postoperative bleeding.5 Increased thoracic and abdominal pressure during retching may produce arterial or venous hypertension. Postoperative bleeding is of particular concern in these patients, as it may produce a neck hematoma with the potential for airway obstruction. We evaluated the incidence of PONV in a series of patients undergoing thyroid and parathyroid procedures. Patients were randomly assigned to one of two anesthetic regimens. We tested the hypothesis that PONV occurs less frequently in patients who receive propofol-nitrous oxide (N,O) for maintenance of general anesthesia than in those who receive isoflurane-N,O. We further analyzed the rates of PONV in women as compared with men and computed the difference in costs between anesthetic techniques.

Materials

ing was treated with droperidol 0.625 mg, and/or metoclopramide (Reglan) 10 mg IV. Postoperative nausea and vomiting were assessed by PACU and ward nurses were unaware of the choice of maintenance anesthetic. Signs and symptoms of nausea and vomiting were graded on a four point scale as 1 = no nausea; 2 = mild nausea; 3 = severe nausea; 4 = retching and/or vomiting. PONV was defined as grades 3 and 4.

Data Analysis We compared the incidence of PONV associated with isoflurane versus propofol. The rate of PONV was further analyzed in men versus women, and in women greater than 55 years of age versus those less than 55. The costs and resources (i.e.> PACU time and duration of hospitalization) associated with each anesthetic regimen were compared. Data were analyzed by Chi-square analysis, Fisher’s exact test, or unpaired t-test (two-tailed) as appropriate. A pvalue less than 0.05 was considered significant. The cost of each anesthetic regimen was determined directly from the doses of the drugs used, except for isoflurane, for which cost was determined using the following formula,

and Methods

After obtaining approval from the UCSF Committee on Human Research and informed consent, we studied 118 ASA physical status I and II, nonpregnant patients aged 18 and older, undergoing elective thyroid or parathyroid resections. Sample size was determined to detect a 25% effect, with (Y = 0.05 and l3 = 0.2 with equal numbers of patients in both groups. Patients were randomly assigned via sealed envelope to receive either isoflurane (0.5% to 1.3% end-tidal concentration) or propofol (50 to 200 Fg/kg/min) for maintenance of anesthesia. Patients in both groups received midazolam 0.03 mg/kg for premeditation, propofol 1 to 2 mg/kg for induction of anesthesia, succinylcholine 1 to 1.5 mg/kg or vecuronium 0.1 mg/kg to facilitate endotracheal intubation, N,O, (50% to 70%)) and fentanyl (up to 250 kg for the first 2 hours of anesthesia and 50 Fg/hour as needed thereafter). Residual neuromuscular blockade, as assessed by train-of-four monitoring, was reversed when present at the conclusion of the operation with neostigmine (40 to 70 kg/kg) and glycopyrrolate (8 to 14 pg/kg). All patients were mechanically ventilated to maintain an end-tidal pC0, of 30 to 35 mm Hg. Routine monitoring included electrocardiography, pulse oximetry, and oscillometric blood pressure. All operations were performed by the same attending surgeon. Pain in the postanesthesia care unit (PACU) was treated by administration of ketorolac 30 to 60 mg intramuscularly (IM), or with fentanyl 25 pg intravenously (IV), as needed to bring the verbal analog pain scale (0 to 10) to less than 4. Pain control after leaving the PACU was with ketorolac 30 mg IM every six hours as needed and/or with oral acetaminophen, 650 mg every four hours as needed. Prophylactic antiemetics were not administered. Nausea and/or vomit-

thyroid surgery: Sonner et al.

Cost = (%)(FGF)(t)($)/l9.5 where % is the vaporizer dial setting (% concentration of isoflurane), FGF is the fresh gas flow in liters per minute, t is time in minutes, and $ is the cost of isoflurane in dollars/ml of liquid isoflurane.” The factor 19.5 relates to the amount of isofhrrane vapor that is produced from a milliliter of liquid isoflurane at 20°C and one atmosphere of pressure.’ We based our calculations on a mean fresh gas flow of 2.5 liters per minute, at a vaporizer setting of 1.25%, for 150 minutes of anesthesia. At our institution, the current cost of isoflurane is $86/100 ml, and of propofol, $0.50/10 mg.

Results We studied 87 women and 31 men. There were no significant differences between the groups receiving propofol or isoflurane for maintenance of anesthesia with respect to age, gender, weight, thyroid versus parathyroid procedure, preoperative nausea, history of PONV, surgery time (defined as the time from incision to placement of the dressing), anesthesia time, and the administration of drugs to reverse neuromuscular blockade (Table I). Patients in the propofol group received slightly more fentanyl (242 2 75 kg) than did those in the isoflurane group (214 ? 80 kg). The overall incidence of PONV during hospitalization in our patients was 54%. PONV was significantly more common after isoflurane (64%) than after propofol (44%) (Table 2). Women given isoflurane had a significantly greater incidence of PONV than those receiving propofol (71% vs. 42%). Rates in men did not differ by anesthetic (47% with isoflurane us. 50% with propofol). In J.

Clin.

Anesth.,

vol. 9, August

1997

399

Original Contributions Table

1.

Demographics

and Perioperative

Parameter Thyroidectomies Parathyroidectomies Age (years) t Weight (kg)? PACU time (minutes) t Preoperative nausea History of N/V after previous surgery Anesthesia duration? (minutes) Surgery duration (minutes) t Propofol (mg)t Fentiny Wt Patients receiving anticholinesterases

Data

Isoflnrane (n = 59)

Propofol (n = 59)

31 28 51 ? 14 74? 16 81 2 16 6.8% 22%

32 27 48? 13 75 2 16 79 t 20 6.8% 34%

176 + 52

188 + 53

121 + 45 165 + 58 214 _t 80 47%

128 + 49 1713 ? 744” 242 ? 75* 58%

On average, $85.65 of propofol was used per patient in the propofol group, and $10.70 of propofol was used per patient in the isoflurane group. At our mean settings of 2.5 liters per minute fresh gas flow and 1.25% inspired isoflurane, the cost of isoflurane was $20.69 per case. Differences in cost of analgesics, antiemetics, muscle relaxants, anticholinesterases, and anticholinergic drugs, was less than $1.00 per patient between groups. Thus, an additional $54.26 was spent per patient in the propofol group.

Discussion In this study, we found a high incidence of PONV in patients undergoing thyroid or parathyroid surgery. Other head and neck surgeries also are associated with high rates of nausea and vomiting.4,5S8 We hypothesize that vagal stimulation during surgical manipulation of the neck may be responsible. It is unlikely that changes in the level of circulating thyroid hormones play a role in the production of nausea, because, as part of their preoperative preparation, our patients were known to be euthyroid at the time of surgery. Women receiving isoflurane and N,O for maintenance of anesthesia during thyroid or parathyroid surgery had a strikingly high incidence of PONV (71%). Maintenance of anesthesia with propofol/N,O was associated with substantially less PONV in women (42%). This effect was particularly noticeable in the PACU, where the incidence of PONV was only 24% in women receiving propofol versus 57% in women receiving isoflurane. The decreased rate of PONV with propofol for maintenance of anesthesia is consistent with other studies.Y-‘” Propofol is believed to exert an antiemetic effect that is independent of its sedative-hypnotic actions.14 In our study, patients in the isoflurane group also received propofol for induction of anesthesia. Thus, the high rate of PONV in women receiving isoflurane suggests that a single-induction dose of propofol has a limited

*p < 0.05. tMeans 2 standard deviation. PACU = postanesthesia

care unit; N/V = nausea and/or

vomiting,

both groups, women had a significantly higher incidence of vomiting and retching (grade 4) than men (36% vs. 13% overall, p = 0.03) (Table 3). The rate of PONV in women older than 55 years compared with those younger than 55, was not significantly different, 56% and 57%, respectively. Fourteen patients in the isoflurane group and 8 patients in the propofol group required two or more doses of antiemetics (p = 0.24). Differences in PONV between the anesthetic groups were apparent and significant by the time of discharge from the PACU (Table 2); the rate of PONV was 57% in women receiving isoflurane, but only 24% in women receiving propofol. Despite the higher rate of nausea in the isoflurane group, there was no difference in the PACU time (Tubk 1). All patients were discharged on the first postoperative morning except for one, who developed a postoperative hematoma and was not discharged until postoperative day two. That patient had received propofol, had had both nausea and vomiting following surgery, and required reoperation for drainage of the hematoma.

Table 2.

Incidence

of Postoperative

antiemetic

effect

after

Men

Propofol

24% (4/17) 21% (3/14)

*p < 0.005 when compared with isoflurane. tp < 0.05 when compared with isoflurane. PACU = postanesthesia care unit. 400

hours

of anesthesia.

Never-

Nausea and Vomiting At Hospital

At PACU Discharge

Isoflurane

several

theless, maintenance of subhypnotic propofol blood levels by a continuous infusion (1 mg/kg/hour) may be effective at reducing PONV.4 Interestingly, the incidence of PONV in men was the same regardless of anesthetic regimen, that is, the use of

J. Clin. Anesth., vol. 9, August 1997

Women 57%

Total

Men

47%

47% (S/17) 50% (7/14)

(24/G’)

(2ww

24%* (11/45)

24%? (14/59)

Discharge

Women

Total

71%

64% (38/59) 44%-) W/59)

W/W 42%1 (19/45)

Nausea c$er thyroid surgery: Sonner et al. Table 3.

Nausea Scores for Men and Women Isoflurane

Nausea Score

Men n = 17

at Hospital

Discharge

Group Women n = 42

Propofol

Combined

Group

Men n = 14

Women n = 45

Men n = 31

Women n = 87

1 ,4f%,

CA (&

2 3

(L%, 5 (29%)

31” (36%)

4 (Ii%) Scoring was: 1 = no nausea; 2 = mild nausea; 3 = severe nausea; 4 = *p < 0.05 when compared to men with the same nausea score.

propofol

did not result in the expected reduction in This may be an important clinical finding. In contrast to our study, most studies of propofol and PONV in adults have not analyzed for gender differences,“‘,‘” or they have included only women.16-1M Our finding that PONV is not reduced with propofol in men needs to be confirmed in a larger prospective study. Young women undergoing gynecologic surgery have a high incidence of PONV. ‘L0-22 The phase of menstrual cycle and the associated hormonal changes has been suggested as factor influencing PONV, although reports conflict as to which phase is actually at high risk.‘s,24 In a recent study of 1,169 women, there was no relationship between phase of menstrual cycle and incidence of PONV.2’ While we did not specifically assess this, our results show that women older than 55 years, most of whom will be postmenopausal, had a rate of PONV no different from that of women who were younger than 55 years of age. Our data suggest that fluctuating hormonal levels associated with the menstrual cycle may not influence the rate of PONV. Opioids, ” anticholinesterases,27 and N,O” may increase the rate of PONV. Similarly, a history of PONV after previous surgery may increase the likelihood of nausea and vomiting after surgery. In our study, N,O was used equally in both groups. Slightly more patients in the propofol group received anticholinesterase to reverse a neuromuscular blockade. In addition, a larger dose of fentanyl was given to patients in the propofol group. Moreover, a greater number of patients in the propofol group had a history of PONV after previous surgery. Thus, the higher rate of PONV found in the isoflurane group cannot be attributed to these factors. Bleeding at operative sites is a concern following thyroid and parathyroid procedures; an expanding hematoma can compromise the airway. In our study, one patient with nausea and vomiting developed a hematoma. While PONV may have contributed to this single adverse outcome, an association cannot be established because of the low incidence relative to the sample size. The use of propofol versus isoflurane did not affect outcomes such as time to discharge, time in the PACU, or PONV.

retching and/or vomiting.

the rate of local wound complications. Therefore, reducing the incidence of PONV by using propofol was an issue of patient comfort alone. This comfort was achieved at a cost: $54.26 of propofol per case, to achieve a 29% reduction (from 71% to 42% in women, the at-risk group) in PONV. The cost of preventing each case of PONV in women using propofol was thus $187 ($54.26 divided by 0.29). Prophylactic antiemetics, depending on their effL cacy, may be a more cost-effective alternative for these patients. We conclude that patients undergoing thyroid or parathyroid surgery are at high risk of developing PONV. Women, in particular, are very likely to experience PONV. Propofol for maintenance of anesthesia, although more expensive than isoflurane, decreases the incidence of PONV in women but may not in men.

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