Digital assistance of nasogastric tube insertion in intubated patients under general anesthesia: A single-blinded prospective randomized study.

BACKGROUND: Nasogastric tube (NGT) insertion may pose a special problem in patients under general anesthesia with first attempt failure rates up to 50%. To increase insertion success rate and decreases related complications, several techniques have been developed. In this study, digital assistance technique is compared to the classic insertion technique in neck flexion.
MATERIALS AND METHODS: In this prospective randomized study, 160 patients were randomly allocated into two groups; control group (Group C, n = 80) where NGT tube will be inserted with the neck in flexion position and digital facilitation group (Group D, n = 80).
RESULTS: Overall success rate and first attempt success were statistically higher in Group D compared to Group C (94% vs. 81%, P = 0.02, 80% vs. 62%, P = 0.01 respectively) with significantly lower insertion time in Group D (13 ± 5 s. vs. 10 ± 3 s., P = 0.00).
CONCLUSIONS: Digital assistance of NGT insertion in the anesthetized or unconscious patient is an effective, fast, and safe method that can be either used as a routine technique or as a rescue in case of failed other methods.

RCT Entities:   Population Interventions Outcomes

Introduction

Nasogastric tube (NGT) insertion may be an important component in patient care. Conscious patients can help increasing successful insertion attempts by swallowing. Unconscious patients either in intensive care unit or under general anesthesia may pose a special problem with failed insertion in first attempt reaching up to 50% of cases.[12] With repeated insertion attempts, complications such as bleeding, pharyngeal wall injury, coiling, and hypertension also increase.[2]

To increase insertion success rate and decreases related complications, several techniques have been developed. Starting with simply stiffening of NGT by cooling with iced saline, to using a guitar wire, ureteral catheter, or angiography catheter as a stylet.[23] Furthermore, anterior displacement of the larynx or deflation of the endotracheal tube cuff has been tried to facilitate passage into the esophagus.[24] Even more complex methods such as GlideScope or fiber-optic nasoendoscope have been used.[56]

In this study, we used a facilitated technique, in which the NGT is guided directly by anesthetist index finger through the pharynx into the esophagus in intubated patients under general anesthesia. Digital assistance technique is compared to the classic insertion technique in neck flexion regarding first attempt success, overall insertion success rate, and incidence of complications including bleeding, coil, and stress response (tachycardia and hypertension).

Materials and Methods

This prospective randomized study was conducted in Gastroenterology Center, Mansoura University, Egypt. After approval of Institutional Review Board (R/15.10.58) and clinical trial registry (NCT02764632), a written informed consent was obtained from patients indicated for NGT insertion during surgery from October 2015 to May 2016. Patients were of either sex, age ranging from 20 to 60, American Society of Anesthesiologists I to III, and body mass index (BMI) <35. Esophageal surgeries, achalasia, nasal or maxillofacial deformities, history of cervical spine disorders, and patient refusal were considered as exclusion criteria from the study.

For getting a power of 85% with accepted alpha error of 0.05, a sample size of 160 cases was calculated to be sufficient to detect a 30% improvement in the first attempt success (using G*Power software version 3.1.9.2, Franz Faul, Universität Kiel, Germany). A computerized random table was generated to allocate patients into either of two groups (in 8 blocks of 20); control group (Group C, n = 80) where NGT tube will be inserted with the neck in flexion position. Digital facilitation group (Group D, n = 80) where the anesthetist will use the index finger to facilitate NGT advancement, see study flow chart [Figure 1].

Figure 1

Study flow chart

Before admission to operating theater, all patients were asked to inhale alternately through each nostril, the side providing superior flow was used for NGT insertion. General anesthesia was induced using 1–2 mg/kg propofol (propofol 1%, Fresenius), 1 μ/kg fentanyl citrate (fentanyl, Janssen), and 0.5 mg/kg atracurium besilate (atrabesylate, Egypharm). After assuring adequate muscle relaxation, an endotracheal tube was inserted (7.0 mm internal diameter for females and 7.5 mm internal diameter for males). Anesthesia was maintained by sevoflurane. Each nostril is anesthetized using the nasal mucosa was anesthetized using 3 ml of lidocaine 2% gel injected directly into the nasal canal to provide both lubrication and local anesthesia. For all cases, a 16F, 105 cm NGT (Ultramed, Egypt) was used. After lubrication of its distal end, NGT was inserted through the selected nostril for 12 cm then advanced according to study group.

In Group C, the NGT was inserted directly through a selected nostril with the head being maintained in the flexion position. In Group D, after feeling the NGT in the pharynx, with the head in neutral position, the gloved index finger was used to support the NGT with a slight direction toward the left side. This will prevent tube kinking at this point in front of the resistance offered by the inflated tube cuff or arytenoids cartilage. Furthermore, this digital support reinforces the tube at the area weakened by its openings.

After insertion of the NGT, the surgeon was asked to confirm NGT proper placement in the stomach. If the surgeon could not confirm proper placement, the oral cavity was explored using a laryngoscope to detect kinking of the tube. If the NGT was coiled inside the mouth, it was withdrawn to the nasal cavity and reinserted. After three attempts failed to place the NGT, the case is recorded as a failed case, and additional maneuvers, such as anterior displacement of the larynx, turning the patient's neck to the lateral position, using a laryngoscope and Magill forceps, and other methods, were used to aid the successful passage of the NGT.

Patients’ age, weight, height, and BMI were recorded. Heart rate and mean arterial pressure will be recorded immediately before NGT insertion and then each minute for 5 min and maximum change from basal reading was recorded. The number of attempts required for successful insertion was recorded. Successful NGT insertion was defined as when the NGT was inserted within three attempts. The time required to insert the NGT (from nasal insertion to confirmation by the surgeon) was measured, and nasal or mucosal bleeding was checked.

Statistical analysis was performed using SPSS 20 for Windows (SPSS Inc., Chicago, IL, USA). Continuous variables were recorded as mean ± standard deviation or median (interquartile range) according to the normality of distribution. Nominal and ordinal variables were recorded as number and percentage. Independent sample t-test, Mann–Whitney U-test, and Chi-square test were used to detect differences between the two groups as appropriate. Results were considered statistically significant when P < 0.05.

Results

No statistically significant differences were found in patients’ characteristics in the two studied groups as shown in Table 1. As shown in Figure 2, Overall success rate and first attempt success were statistically higher in Group D compared to Group C (94% vs. 81%, P = 0.02 and 80% vs. 62%, P = 0.01, respectively). However, the second attempt success rate was statistically comparable in the two groups. Simultaneously, insertion time was significantly lower in Group D (13 ± 5 s. vs. 10 ± 3 s, P = 0.00).

Table 1

Characteristics of patients in the two studied groups

Figure 2

Success rates for nasogastric tube insertion in the two studied groups data are presented as a mean ± standard deviation or percentage. *P value is significant if less than 0.05

In Table 2, incidence of bleeding, tube coiling and the mean change in heart rate were significantly higher in Group C (25% vs. 10%, P = 0.01, 37% vs. 22%, P = 0.04, and 4[15] vs. 1 [17], P = 0.00). In contrast, no other related complications could show statistically significant differences between the two studied groups.

Table 2

Complications related to nasogastric tube insertion in the two studied groups

Discussion

Insertion of NGT in intubated patients under general anesthesia could be a frustrating experience. First attempt failure rates may reach 50% when inserted with head in neutral position. Such challenges are attributed to both anatomical constrictions along the tube journey toward the stomach or tube design that in most times is adding to insertion difficulties.[378] Modern NGT is made up of polyurethane aiming to be soft enough to be less traumatic. However, this assumed advantage plus multiple holes at the distal end and the preformed curvature increase liability of tube kinking, especially when exposed to body temperature even for a short period. In intubated patient, pressure by the air-filled cuff may also have a deleterious role.[79]

The most common sites for tube impaction and kinking are the piriform sinuses and arytenoid cartilages.[10] Simple maneuvers have been tested to avoid NGT kinking including cooling the NGT to increases its stiffness,[11] head flexion, lateral neck pressure, turning the head to one side, and forward displacement of the larynx (Reverse Sellick's maneuver).[2121314] Other sophisticated techniques to facilitate NGT insertion include the use of a ureteral guidewire, the use of a slit endotracheal tube as a conduit, and the use of a guitar wire as a stylet, endoscopic placement.[45610151617]

In our study, with the head in neutral position, the index finger was used to support the NGT with a slight direction toward the left side. This will prevent tube kinking at this point in front of the resistance offered by the inflated tube cuff or arytenoids cartilage. Furthermore, this digital support reinforces the tube at the area weakened by its openings. As a result, the overall success rate and first attempt success were significantly higher than in Group C. Subsequently, such higher success rate resulted in significantly lower insertion time

Most of the complications related to NT insertion (kinking and bleeding, pharyngeal wall injury, and stress response) are increased with multiple attempts.[379] These complications were found to be significantly lower in D Group than in C Group. This is obviously related to the previously described higher success rate and lower number of attempts in Group D.

Limitations

There were a few limitations in this study. This study is not a double-blinded study. Morbid obese and patients with cervical mobility disorders were excluded from the study. However, the technique should be tested in patients with high risk of NGT insertion difficulty.

Conclusions

This study showed that using digital assistance of NGT insertion in anesthetized or unconsciousness patient is an effective, fast, and safe method that can be either used as a routine technique or as a rescue in case of failed other methods.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.