Regurgitation is the passive retrograde migration of acidic gastric contents into the oropharynx and/or nasopharynx (Figures 1 and 2). Gastro-oesophageal reflux differs from regurgitation, in that it is the ‘silent’ passage of gastric contents into the oesophagus, and often goes unnoticed as the stomach contents cannot be visualised (Table 1). Subclinical reflux into the oesophagus may occur in up to 55% of anaesthetised patients (Wilson et al, 2005). Patients who experience regurgitation must have already experienced gastro-oesophageal reflux.
Table 1. Definition of regurgitation and reflux
| Regurgitation | Passive movement of stomach contents into the oropharynx and nasopharynx |
| Reflux | Passive ‘silent’ movement of stomach contents into the oesophagus |
The severity of complications depends on the immediate management of the episode and can include oesophagitis, rhinitis, aspiration pneumonia, oesophageal stricture and, in some cases, death.
Regurgitation has been reported to occur between 0.4–5.5% of dogs (Raptopoulos and Galatos, 1997; Wilson et al, 2006). Gastro-oesophageal reflux happens when the effectiveness of the lower oesophageal sphincter is decreased, usually by administration of anaesthetic agents. It has been documented to occur post pre-medication, intra-operatively and postoperatively. The causes for reflux and regurgitation are likely to be related (Galatos et al, 2001). They can also cause the same complications (with the exception of aspiration pneumonia for reflux, as the gastric contents enter only the oesophagus).
The passive movement of gastric acid can cause irritation and damage to the mucosa of the oesophagus, nasopharynx and oropharynx. Regurgitation under anaesthesia represents the most commonly reported cause of oesophagitis and oesophageal stricture formation – a severe complication (Willard and Weyrauch, 2000).
Risk factors
In orthopaedic practice, an increase in incidence of gastro-oesophageal reflux reported in patients undergoing surgery has been recognised. Possible causes include longer anaesthesia duration, patient position and movement during the operation (Lamata et al, 2012). Similar studies have found that intra-abdominal surgery and airway surgery also carry a greater risk of gastro-oesophageal reflux.
During patient assessment, it is important to consider pre-medication selection. Certain medications, including the use of morphine and non-steroidal anti-inflammatory drugs, can increase the risk of gastro-oesophageal reflux. Wilson and Walshaw (2004) and Wilson et al (2005) discussed that in animals, morphine, propofol, xylazine and atropine all decrease lower oesophageal sphincter tone, increasing the likelihood of reflux occurring.
Lamata et al (2012) evaluated the risks of passive regurgitation and hypothesised that patient age, weight, duration of fasting, procedure performed and specific anaesthetic agents are associated with the risk of gastro-oesophageal reflux. A similar study supported this conclusion, stating that breed, size, weight and chest conformation have been shown to be significant, with brachycephalic breeds and deep-chested dogs being at an increased risk of experiencing gastro-oesophageal reflux (Anagnostou et al, 2015).
Other common risk factors that increase the risk of regurgitation
- Prolonged fasting of more than 10 hours
- Prolonged anaesthesia
- Orthopaedic surgery
- Intra-abdominal surgery
- Airway surgery
- Large, deep-chested conformation
- Brachycephalic conformation
- Pregnancy
- Pre-existing oesophageal disease/gastritis/oesophagitis
- Pre-existing vomiting
- Obstruction of the gastrointestinal tract/foreign bodies
- Morphine administration
- Non-steroidal anti-inflammatory drug administration
- Geriatric patients.
Feeding guidelines
The fasting duration before anaesthesia seems to influence the incidence of gastro-oesophageal reflux, and there is a lot of discussion about the proper fasting guidelines in humans and animals. The overall goal of fasting patients is to reduce the volume of stomach contents to prevent gastro-oesophageal reflux, regurgitation and aspiration of stomach contents (Robertson et al, 2018).
Timings of fasting can be influenced by many variable factors including patient age, weight and pre-existing diseases, such as diabetes. For instance, in very young puppies and kittens, it is recommended to withhold food for no longer than 1–2 hours before surgery. Although not all evidence agrees, in general, the recommended fast duration for healthy adult patients has decreased. The change is based on experimental evidence of the benefits of shorter fasting, including a lower incidence of gastro-oesophageal reflux and a higher gastric pH (Raptopoulos and Galatos, 1997; Savvas et al, 2016).
Grubb et al (2020) supported this suggested change, stating that food should be withheld 4–6 hours before surgery (Table 2). However, some conflicting evidence concluded that feeding a light meal 3 hours before surgery was associated with greater odds of reflux and regurgitation, compared to withholding food overnight (Viskjer and Sjöström, 2017).
Table 2. Recommendations of fasting times before anaesthesia (Grubb et al, 2020)
| Patient status | Withhold water | Withhold food |
|---|---|---|
| Healthy | 0 hours | 4–6 hours |
| Less than 8 weeks of age or less than 2 kg in weight | 0 hours | No longer than 1–2 hours |
| Diabetic | 0 hours | 2–4 hours |
| History of regurgitation | 6–12 hours | 6–12 hours |
| Emergency | 0 hours | 0 hours |
Post-anaesthesia complications such as oesophagitis after a regurgitation episode may be uncomfortable, painful and may affect the patient's willingness to eat in the post-operative period. Ideally the patient needs to be fed as soon as practical and safe to do so, in order to reduce the acidity of stomach contents and prevent oesophageal stricture formation (Woolfe, 2014). Continued monitoring of the patient is recommended for signs of oesophagitis, pharyngitis, rhinitis, oesophageal stricture and aspiration pneumonia. This includes malaise, inappetence, nausea, further regurgitation, vomiting, food aversion, lip smacking, hypersalivation, pyrexia, dyspnoea and potential coughing. Some of these clinical signs may not be evident for 2 weeks, therefore it is extremely important to educate the client on the regurgitation incident and possible clinical signs of complications after the patient is discharged. It is worth considering omeprazole 1 mg/kg q12 orally or intravenously for 5 days and sucralfate 2–5 ml orally q8 for 2–5 days, as instructed by the veterinary surgeon, to try and reduce gastric acidity to aid patient comfort (Lotti et al, 2018).
Pre-emptive treatment
The use of gastroprotectants and anti-nausea medication pre-operatively has been the subject of debate for their ability to reduce the incidence of gastro-oesophageal reflux (Marks et al, 2018). Maropitant prevents vomiting and is suggested to promote a more rapid return to normal feeding, improving the quality of recovery from anaesthesia (Grubb et al, 2020). However, Ramsey et al (2014) concluded this to have no impact on the incidence of reflux or regurgitation. Metoclopramide, ranitidine and omeprazole plus maropitant also have a minimal impact on regurgitation (Lotti et al, 2018). Gastro-oesophageal reflux and regurgitation were reduced when cisapride was combined with omeprazole (Zacuto et al, 2012); however, further research studies are required in this area to consider this a significant finding.
Reflux and regurgitation cannot be consistently prevented with the use of gastro-protectants; however, the use of proton pump inhibitors – such as omeprazole – administered the evening before and the morning of the operation can help to neutralise pH in high-risk patients (Lotti et al, 2018).
Treatment of regurgitation
The measurement of pH is the diagnostic tool for gastro-oesophageal reflux to ultimately prove if the fluid regurgitated is gastric contents. This is the first part of the recommended treatment. The pH test can be carried out on fluid appearing at the mouth or nose. If the pH is less than 7, the fluid is gastric in origin.
It has been heavily debated in recent years whether to lavage the oesophagus after reflux or regurgitation, to improve the pH levels and prevent further damage of the acidic fluid on the oesophagus. Lavage can be a traumatic treatment when trying to insert the catheter into the oesophagus and may cause iatrogenic damage.
The treatment of regurgitation is focused on pH neutralisation and removal of fluid and debris. Allison et al (2020) looked at the effect of pH levels with two common treatments – lavage vs instilling bicarbonate – to conclude which is superior. The study found that lavage is no longer recommended as it did not further improve the final oesophageal pH if bicarbonate was instilled.
Table 3 shows the recommended steps to take when regurgitation is noted during anaesthesia.
Table 3. Recommended steps to take when regurgitation is noted during anaesthesia
| 1. | Immediately ensure the endotracheal tube is inflated/placement of an endotracheal tube to secure the airway may need to be performed during suction and In a head down position |
| 2. | Remove any probes such as oesophageal probes or temperature probes |
| 3. | Place the animal's head over the edge of the table If appropriate to do so |
| 4. | Test the pH of the regurgitated fluid:
|
| 5. | Suction the oropharynx and oesophagus |
| 6. | Check the patient's eyes are clear, If any doubt of contamination, copiously cleanse with eye flush or water and apply lubricant |
| 7. | Place a throat pack |
| 8. | Lavage nasal cavity with warm water until fluid runs clear and allow drainage |
| 9. | Instil bicarbonate. The author uses: 10 ml (If less than 15 kg) or 20 ml (If more than 15 kg) of 4.2% bicarbonate Into the oesophagus. To reconstitute the bicarbonate, add 20 ml water to 0.8 g of bicarbonate powder |
| 10. | Using a laryngoscope to visually assess the pharynx to ensure fluid/throat pack/debris Is cleared following lavage |
| 11. | Remove throat pack |
| 12. | Dry the patient, check the patient's body temperature If substantial wetting has occurred |
| 13. | Delayed tracheal extubation should be performed when the swallowlng/gag reflex has returned
|
| 14. | Place a reminder warning on the clinical notes and detailed notes |
| 15. | Consider omeprazole prescription or sucralfate |
Suggested equipment checklist
It is suggested that the following equipment is kept to hand during anaesthesia (Figure 3):
- Standard of practice protocol
- Mobile suction unit (Figure 4)
- Suction tubing
- Disposable suction tip
- Throat packs
- pH test strips (Figure 5)
- 50 ml catheter tip syringe
- Selection of 5 ml, 20 ml, and 60 ml luer tip syringes
- Incontinence pads or towels
- 0.8 g bicarbonate preloaded into 20 ml labelled syringes
Conclusions
Providing quality patient care through scientific and knowledge-based practice is the goal of veterinary medicine. For untrained staff to be expected to manage an episode of gastro-oesophageal reflux is unacceptable and can be stressful for the individual. It could compromise patient care with procedural mistakes. This will ultimately affect the outcome for the patient. Gastro-oesophageal reflux has complicated after-effects if not dealt with using evidence-based methods. The main interventions for gastro-oesophageal reflux extend to coaching and advising the owners on the ideal fasting times, managing and identifying patients at greater risk, careful selection of pre-medication and preventative medications to reduce the occurrence. Correct and swift treatment at the time of the adverse incident and providing good aftercare of the patient is paramount. If these factors are all considered and treatment is executed well, veterinary professionals can reduce the common complications associated with gastro-oesophageal reflux and improve patient care.
KEY POINTS
- Regurgitation is the passive retrograde migration of acidic gastric contents into the oropharynx and/or nasopharynx.
- Gastro-oesophageal reflux is the ‘silent’ passage of gastric contents into the oesophagus, and often goes unnoticed as the stomach contents cannot be visualised.
- The severity of complications depends on the immediate management of the episode and can include oesophagitis, rhinitis, aspiration pneumonia, oesophageal stricture and, in some cases, death.
- The measurement of pH is the diagnostic tool for gastro-oesophageal reflux to determine if the fluid regurgitated is gastric contents.