Preoperative Oral Hydration in Gynecologic Laparoscopy

Abstract

Background: Having patients fast for at least 8 hours prior to surgery to decrease aspiration risk continues today in most institutions despite literature supporting the benefits of intake of clear liquids before surgery. National guidelines, in the United States and Europe, recommend an 8-hour fast from fatty foods but allow clear liquids up to 2 hours prior to surgery. This ingestion has been shown to have no effect on residual gastric volume, even in obese patients. Objective: The aim of this study was to evaluate the effect of preoperative oral hydration with a commercial, clear-liquid nutritional supplement, Nestlé's Breeze (Nestlé HealthCare Nutrition, Inc., Florham Park, NJ), on the gastric volume and pH of patients awaiting laparoscopic gynecologic surgery, compared to the same effects of standard preoperative fasting. Materials and Methods: For this pilot study, at a tertiary care hospital, 60 patients were studied. Thirty study patients ingested the product and ad libitum clear liquids before surgery and 30 control patients underwent standard preoperative fasting. All of the patients were instructed to take famotidine preoperatively, but some patients did not take this drug. After induction of anesthesia, gastric volume and pH were assessed in all patients. Results: Patients who had ingested the product had a mean gastric volume of 12.4 mL with a pH of 3.5 when they received famotidine and 3 when they had not received famotidine, while patients who underwent standard preoperative fasting had a gastric volume of 23.1 mL with a pH of 4.1 when they had received famotidine and 1.7 when they had not received famotidine. Conclusions: A clear-liquid nutritional supplement, ingested at least 2 hours prior to laparoscopic surgery, did not increase gastric volume or decrease pH, compared to conventional preoperative fasting and is an efficient way to provide nutrition and hydration to patients prior to laparoscopic surgery. (J GYNECOL SURG 31: 135)

Introduction

Patients typically have fasted for 6–8 hours prior to elective surgery in order to reduce residual gastric volume and, thereby, the likelihood of pulmonary aspiration of gastric contents during induction of anesthesia. The practice of preoperative fasting to decrease the risk of aspiration continues today despite literature supporting the benefits of intake of clear liquids before surgery. National guidelines, both in the United States and Europe, recommend an 8-hour fast from fatty foods but allow clear liquids up to 2 hours prior to surgery.^1,2 Ingestion of clear liquids up to 2 hours before surgery has been shown to have no effect on residual gastric volume, even in obese patients.³

However, most centers in the United States are reluctant to adopt this fasting as clinical practice and continue to instruct patients to fast, from both solids and liquids, for at least 8 hours preoperatively. The rationale for this practice originates in the concern that increased gastric volume could increase the risk of aspiration and the belief that fasting reduces gastric volume, while ingestion of liquids increases residual gastric volume. The critical values for volume and pH of the aspirate have conventionally been 25 mL and 2.5, respectively.⁴

Administering an oral, clear-liquid carbohydrate drink has produced benefits, such as decreased preoperative hunger, thirst, and weakness.^5,6 An approach that combines several elements during the preoperative and postoperative period, with consistent clinical practices during the intraoperative period, is called an enhanced recovery after surgery (ERAS) pathway. This approach could lead to improvement in patient care. The ERAS pathway has been shown, in several fields—including gynecology, colorectal surgery, and urology—to decrease the length of hospital stay.^7–9 Prevention of starvation and dehydration is a key element of the implementation of an ERAS pathway.

The current authors performed a study to determine the effect of preoperative ingestion of a clear liquid, containing carbohydrates and elemental amino acids, as part of an ERAS pathway, in patients awaiting laparoscopic gynecologic surgery. The study goal was to determine the effect of preoperative ingestion of a specific clear liquid, a commercially available, nutritional supplement, Nestlé Breeze™ (Nestlé HealthCare Nutrition, Inc., Florham Park, NJ), on the gastric volume and pH of patients awaiting elective surgery, and compare this effect to the effects of undergoing standard preoperative fasting.

Materials and Methods

In this open-label, pilot study, 60 adult patients undergoing laparoscopic gynecologic surgery, who consented to participate, were studied in one hospital over a 2-month period. The local institutional review board approved this study (under IRB # 40118EP) on May 30, 2013. The patients were not randomized. Thirty patients acted as controls and received standard preoperative fasting instructions, which involved fasting from solid food after midnight and liquids for 2 hours prior to surgery, while 30 study patients were instructed to drink the clear liquid (Nestlé Breeze) 2 hours before their scheduled time of surgery, usually just before arriving at the hospital.

Study patients fasted from solid food after midnight prior to the day of surgery. In addition, they drank clear fluids ad libitum and 1 serving of Nestlé Breeze, until 2 hours prior to surgery. Nestlé Breeze is a new commercially available product, classified as a clear liquid, nonparticulate supplement, which contains protein in the form of amino acids. One 8-oz serving (237 mL) of the ingested Nestlé Breeze contains 9 g of protein as amino acids (the protein source is whey isolate) and 250 calories (86% carbohydrate, 14% protein, 0% fat). The American Society of Anesthesiologists guidelines allowing for ingestion of clear liquids until 2 hours before surgery usually apply to water or a clear nonparticulate juice, that contains carbohydrates alone.^1,2 The addition of protein to a meal or drink has the potential of prolonging satiety by delaying gastric emptying. Time to gastric emptying following ingestion of this drink is not known.

One minimally invasive gynecologic surgeon dispenses Nestlé Breeze to patients as one element of his ERAS pathway quality-improvement project. For this study, patients were approached in the preoperative holding area and verbal consent was obtained and documented for involvement in the study. These patients were compared to patients who followed the standard 8-hour fast from solids and 2-hour fast from liquids and did not receive the Nestlé Breeze drink. A convenience sample of 30 patients in each group was chosen based on similar studies.^10,11

Orogastric tubes are routinely placed in patients during surgical clinical care when they undergo gynecologic laparoscopic procedures. After induction of anesthesia using intravenous (i.v.) drugs and tracheal intubation, prior to surgery, a multiorificed orogastric tube was inserted in each patient, and gastric contents were suctioned, using a 70-mL Toomey syringe, and the volume was measured (Bard Medical Covington, GA).

The pH of the gastric fluid was determined using the comparison chart on the test card of a Gastroccult Test (Beckman Coulter Inc., Brea, CA). The pH scale also provided the clinically relevant range for monitoring antacid prophylaxis.The investigator (J.A.B.) who obtained and measured the samples was blinded to which cohort each patient belonged and the time of that patient's last meal.

Patients had been instructed to take 20 mg of oral famotidine (a histamine-2 receptor antagonist) prior to arrival at the hospital, as part of the ERAS quality-improvement project, but some patients did not follow instructions to take the drug. Gastric volume and pH were measured in all enrolled patients regardless of whether or not they had taken the famotidine as part of their management. This study was designed to observe the impact of interventions in a clinical setting; as an effectiveness trial rather than as an efficacy study. All patients received general anesthesia, using standard i.v. induction with maintenance on an inhaled anesthetic agent with air and oxygen. This was supplemented by intraoperative and postoperative opioids and nonsteroidal anti-inflammatory drugs for analgesia, with a two- or three-drug combination for postoperative nausea and vomiting (PONV) prophylaxis, per standard hospital practice. All patients underwent outpatient gynecologic laparoscopic procedures.

Study data were collected and managed using the REDCap [Research Electronic Data Capture] application. REDCap is a secure, web-based application designed to support data capture for research studies.¹¹ REDCap provides an interface for validated data entry, audit trails for tracking data manipulation and export, and automated data export procedures for data downloads to statistical packages.

Results

In both the control and the Nestlé Breeze hydration group, orogastric tubes were successfully placed in all patients. Patients who had ingested the clear liquid, on average, 4 hours prior to induction of anesthesia, compared to patients who underwent standard fasting practices, who had a mean time of almost 13 hours prior to surgery. Patients in the standard practice group fasted from 8–17 hours prior to surgery. The results are shown in Table 1.

Table 1.

Gastric Volume and pH in Fasting and Fed Patients ^a

	Nestlé Breeze™ patients (n=30)		Fasting patients (n=30)
Parameter	Famotidine	No famotidine	Famotidine	No famotidine
Hours since last meal^b	4.2±1.5		13.2±4.7
# of patients	28	2	16	14
Hours since famotidine^b	4.1±4.7	N/A	5.5±5.3	N/A
# of patients in whom gastric volume was suctioned	23	2	15	14
Gastric volume in mL^b	12.4±13.4	8±5.7	9.9±12.8	23.1±15.3
# of patients with gastric volume >25 mL	5	0	2	8
# of patients with gastric pH <2.5	8	1	2	14
Gastric pH^b	3.5±1.6	3±2.8	4.1±1.3	1.7±1.3

This table shows the amount of time since the patients' last meal and ingestion of famotidine. It also includes the data for gastric volume and pH.

Values are Mean±standard deviation.

N/A not applicable.

Nestlé Breeze™ manufactured by Nestlé HealthCare Nutrition, Inc., Florham Park, NJ.

In patients who had ingested Nestlé Breeze and taken famotidine, the mean gastric volume was 12.4 mL (SD: 13.4), with a pH of 3.5 (SD: 1.6). In patients who had ingested Nestlé Breeze and did not take famotidine, the mean gastric volume was 8 (SD: 5.7) with a pH of 3 (SD: 2.8). In contrast, in patients who fasted, the mean gastric volume and pH were 23.1 mL (SD: 15.3) and 1.7 (SD: 1.3), respectively. Patients who fasted, and had taken oral famotidine in addition, had a lower gastric volume of 9.9 mL (SD: 12.8) with a higher pH of 4.1 (SD 1.3).

There was no statistical difference in gastric volume between these two groups. In the hydration group, 28 of 30 patients took famotidine preoperatively. Ingestion of the clear nutritional drink did not increase their residual gastric volume. Patients in this group also had a gastric pH comparable to patients who fasted prior to surgery and took famotidine.

In addition, the same parameters were compared in patients who did or did not take famotidine (Table 1). In the control group, 16 patients received famotidine and 14 patients did not. In patients who fasted preoperatively, those who did not take the famotidine, which reduces gastric-acid secretion, had a higher gastric volume of 23.0 mL (SD: 15.3) and a lower pH of 1.7 (SD: 1.3) compared to those patients who did receive famotidine who had a gastric volume of 9.9mL (SD: 12.8) with a pH of 4.1 (SD: 1.3). Oral famotidine administered prior to surgery had an impact on both gastric volume and pH in terms of reducing gastric volume and acidity, but this effect was not statistically significant.

Because of the sample size in each group, the distribution of gastric pH values for all patients was included, as shown in Table 2. There were 11 patients in the Nestlé Breeze group and 10 patients in the fasting group with a pH of 6. In addition, there were 5 patients in the fed group with a very acidic pH of 1, while 10 patients in the fasting group had the same pH. There were 5 patients in the Nestlé Breeze group and 1 patient in the fasting group who had a gastric volume of 0 and, therefore, the pH could not be measured. As shown in Table 2, oral famotidine use varied across the groups in terms of time of administration prior to surgery and this has an impact on reducing gastric acidity and increasing gastric pH.

Table 2.

Process Variables: Trend of Famotidine Use and Gastric pH ^a

	Nestlé Breeze™ patients	Fasting patients
Parameter	(n=30)	(n=30)
Famotidine taken night before surgery	3	4
Famotidine taken morning of surgery	5	5
Famotidine given in the preoperative holding area	20	7
Did not receive famotidine	2	14
Patients in whom gastric aspirate was 0 and pH could not be measured	5	1
Gastric pH 6	11	10
Gastric pH 4	3	3
Gastric pH 3	2	2
Gastric pH 2	4	4
Gastric pH 1	5	10

This table shows the use of famotidine in each group and the number of patients and corresponding gastric pH for each group.

Nestlé Breeze™ manufactured by Nestlé HealthCare Nutrition, Inc., Florham Park, NJ.

Overall, there was no significant difference in gastric volume between patients who received preoperative oral hydration, with a clear-liquid nutritional supplement containing carbohydrates and amino acids, and patients who were fasted.

Discussion

Patients awaiting surgery are generally instructed to abstain from solid and liquid oral intake starting at midnight before surgery. This recommendation persists despite American and European Anesthesia Society guidelines that support the use of clear liquids until 2 hours preoperatively. Concern that increased gastric volume and decreased gastric pH from oral intake can lead to risk of aspiration continues to persuade anesthesiologists and surgeons to require preoperative fasting from liquid intake for >8 hours. Using oral clear liquids instead of i.v. fluids for preoperative hydration is easy and practical. The use of a new, clear-fluid nutritional supplement that contains elemental amino acids could augment this process. This protein-based supplement was included as part of an ERAS pathway. Use of such preoperative hydration could potentially change the standard of perioperative care for all patients undergoing surgery, not just the current authors' patient population.

Many existing studies have focused on the use of perioperative carbohydrate-based supplements. In a randomized trial of patients undergoing laparoscopic cholecystectomy, patients randomized to a carbohydrate drink had a lower incidence of PONV, compared to those who received a placebo.¹² A review of the colorectal literature regarding preoperative hydration and use of a carbohydrate supplement concluded that this practice should be implemented in routine practice because of the safety profile, decreased length of stay, and reductions in PONV and pain scores.¹³ In a multicenter randomized controlled trial in Japan, the investigators used gastric volume, gastric pH, fractional excretion of sodium, and fractional excretion of urea nitrogen to measure safety and feasibility of preoperative hydration in a low-risk population.¹⁴

This pilot study was performed as part of a quality-improvement project the current authors' institution, in collaboration between the departments of anesthesiology and gynecology. The study was performed to assess the effect of preoperative oral hydration on gastric volume and pH. Patients were allowed to drink clear liquids, including some patients who drank a clear protein drink, until 2 hours prior to surgery in accordance with the American and European Anesthesia guidelines.

Strengths of this study included the prospective design. Unlike in other studies, the patients in the current study were administered a clear liquid supplement containing protein in the form of elemental amino acids. A single minimally invasive gynecologic surgeon treated all patients included in this study, which standardized the surgical technique. In addition, a single individual who was blinded to the patient group collected the gastric pH data to minimize variation in pH color interpretation.

Although the current authors' quality-improvement project included a large number of patients, this particular study focused on a small sample. The inconsistent use of famotidine may act as a confounder. To account for this, the current authors specifically compared the data of patients who did or did not take famotidine. The guidelines from the American Society of Anesthesiologists indicate that, while famotidine reduces gastric volume and acidity effectively, routine use of this drug preoperatively is not indicated.¹³ The study results indicate that, in patients who ingested Nestlé Breeze, the gastric pH values were similar, whether or not they took famotidine. In the control group, in the absence of clear-liquid intake, administration of famotidine markedly decreased gastric acidity.

If a nutritional supplement, given at least 2 hours prior to surgery, does not increase gastric volume or decrease gastric pH, compared to the conventional practice of fasting, it seems that the supplement is a practical means of providing nutrients to patients awaiting surgery. This study illustrated the process of providing routine gynecologic laparoscopy patients with preoperative hydration and a preoperative nutritional drink. Preoperative hydration and a nutritional protein drink did not increase gastric volume or decrease the gastric pH. Routine use of a histamine-2 receptor agonist may not be necessary.

Overall, patients were subjectively satisfied with this process. However, the current authors did not specifically study patient-satisfaction scores or the incidence of nausea and vomiting during this study. These parameters could serve as areas of inquiry for future studies.

Conclusions

Preoperative fasting from oral liquid intake has long been the standard of care despite anesthesia guidelines that support ingestion for clear liquids until 2 hours prior to surgery. The current authors advocate a preoperative hydration pathway, with oral ad libitum hydration with clear fluids and a clear protein drink, in patients undergoing laparoscopic gynecologic surgery at the current authors' institution and beyond. In their clinical practice, the authors continue to use preoperative hydration with clear fluids of the patient's choice and Nestlé Breeze as an element of an ERAS pathway.

Footnotes

Disclosure Statement

Drs. Riley, Harkins, and Rao, and Mr. Baer have no conflicts to report.

References

Smith

, Kranke

, Murat

, et al.; European Society of Anaesthesiology. Perioperative fasting in adults and children: Guidelines from the European Society of Anaesthesiology. Eur J Anaesthesiol, 2011; 28:556.

American Society of Anesthesiologists Committee. Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: Application to healthy patients undergoing elective procedures. An updated report by the American Society of Anesthesiologists Committee on Standards and Practice Parameters. Anesthesiology, 2011; 114:495.

Maltby

, Pytka

, Watson

, McTaggart Cowan

, Fick

. Drinking 300 mL of clear fluid two hours before surgery has no effect on gastric fluid volume and pH in fasting and non-fasting obese patients. Can J Anaesth., 2004; 51:111.

Roberts

, Shirley

. Reducing the risk of acid aspiration during cesarean section. Anesth Analg, 1974; 53:859.

Hausel

, Nygren

, Lagerkranser

, et al. A carbohydrate-rich drink reduces preoperative discomfort in elective surgery patients. Anesth Analg, 2001; 93:1344.

Yildiz

, Gunal

, Yilmaz

, Yucel

. Oral carbohydrate supplementation reduces preoperative discomfort in laparoscopic cholecystectomy. J Invest Surg, 2013; 26:89.

Aarts

, Okrainec

, Glicksman

, Pearsall

, Victor

, McLeod

. Adoption of enhanced recovery after surgery (ERAS) strategies for colorectal surgery at academic teaching hospitals and impact on total length of hospital stay. Surg Endosc, 2012; 26:442.

Karl

, Buchner

, Becker

, et al. A new concept for early recovery after surgery in patients undergoing radical cystectomy for bladder cancer: Results of a prospective randomized study. J Urol, 2014; 191:335.

Yoong

, Sivashanmugarajan

, Relph

, et al. Can enhanced recovery pathways improve outcomes of vaginal hysterectomy? Cohort control study. J Minim Invasive Gynecol, 2014; 21:83.

10.

Perrone

, da-Silva-Filho

, Adôrno

, et al. Effects of preoperative feeding with a whey protein plus carbohydrate drink on the acute phase response and insulin resistance: A randomized trial. Nutr J, 2011; 10:66.

11.

Harris

, Taylor

, Thielke

, Payne

, Gonzalez

, Conde

. Research electronic data capture (REDCap)—a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform, 2009; 42:377.

12.

Hausel

, Nygren

, Thorell

, Lagerkranser

, Ljungqvist

. Randomized clinical trial of the effects of oral preoperative carbohydrates on postoperative nausea and vomiting after laparoscopic cholecystectomy. Br J Surg, 2005; 92:415.

13.

Jones

, Badger

, Hannon

. The role of carbohydrate drinks in pre-operative nutrition for elective colorectal surgery. Ann R Coll Surg Engl, 2011; 93:504.

14.

Itou

, Fukuyama

, Sasabuchi

, et al. Safety and efficacy of oral rehydration until 2 h before surgery: A multicenter randomized controlled trial. J Anesth, 2012; 26:20.