What is Anticipatory Nausea and Vomiting?

Anticipatory nausea and vomiting is widely believed to be a learned response to chemotherapy that 25% of patients develop by the fourth treatment cycle. This can also be known as a conditioned response. The risk of ANV tends to increase with the number of cycles received and the symptoms may persist long after the completion of chemotherapy. 

As this is a psychological response, it is triggered by objects, smell, taste and sounds that remind you of treatment. Cancer treatment results in nausea and vomiting. After frequent pairings of cancer treatment and the clinic's sights, smells, and sounds, the responses (nausea and vomiting) can be triggered in the absence of any treatment by the clinic's sights, smells, or sounds. 

The three distinct but interrelated factors contributing to ANV are:

1) Classical conditioning, which may lead to anticipatory nausea

2) Clinical and treatment-related factors, which can predict risk to anticipatory nausea

3) Anxiety or negative expectancies, which may prompt and increase sensitivity to anticipatory nausea. Check out the example below. 

How Anticipatory Nausea works

First few chemo sessions:
Conditioned Stimulus (Nurse) = No response 
Unconditioned Stimulus (Chemo drugs) = Unconditioned Response (Nausea)

After several chemo sessions 
Conditioned Stimulus (Nurse) = Conditioned Response (Nausea) 

Although it’s difficult to predict which patients will develop ANV, many factors seem to put some people at higher risk, including:

• Being younger than 50 or female.
• Experiencing nausea and vomiting after treatment, particularly if symptoms ranged between moderate and intolerable.
• Experiencing generalised weakness, lightheadedness, dizziness or sweating after previous treatments.
• Experiencing high levels of anxiety in reaction to specific situations. 

Nausea prevention

This response can be reduced through certain techniques and the earlier you employ these techniques the easier it will be to interrupt the pattern. The techniques focus on enhancing feelings of control and relaxation before treatment.

It has been shown that relaxation techniques can significantly reduce nausea, particularly if they are used regularly. Besides helping you relax, music, deep breathing, and imagery (visualising something pleasant: a special place, for example) can be used to control feelings of anxiety and to sleep better.

Nausea treatment

1. Systematic Desensitisation
This is a type of behavioural therapy based on the principle of classical conditioning.This therapy aims to remove the fear response of a phobia, and substitute a relaxation response to the conditional stimulus gradually using counter-conditioning. The patient works their way through, visualising each anxiety provoking event while engaging in the relaxation response. 

2.  Hypnosis
Hypnosis may help treat symptoms of anxiety, phobias and post-traumatic stress. It is a trance-like mental state in which people experience increased attention, concentration, and suggestibility. While hypnosis is often described as a sleep-like state, it is better expressed as a state of focused attention, heightened suggestibility, and vivid fantasies. People in a hypnotic state often seem sleepy and zoned out, but in reality, they are in a state of hyper-awareness. 

3.  Acupuncture
Some people gain relief from acupressure bands, which are available from chemists. These elasticated wrist bands have a button which presses on an acupuncture point (also called Neiguan) known to reduce nausea and vomiting. You can do this without an acupressure band, read 'The Neiguan Acupressure Point' blog post for more information. 

4.  Progressive Muscle Relaxation
A deep relaxation technique, based upon the simple practice of tensing, or tightening, one muscle group at a time followed by a relaxation phase. 

Muscle Relaxation technique to reduce nausea

1. While inhaling, contract one muscle group (for example your upper thighs) for 5 -10 seconds, then exhale and suddenly release the tension in that muscle group.
2. Give yourself 10 - 20 seconds to relax, and then move on to the next muscle group.
3. While releasing the tension, try to focus on the changes you feel when the muscle group is relaxed. Imagery may be helpful in conjunction with the release of tension.
4. Gradually work your way up the body contracting and relaxing each muscle group.

For more help and tips on reducing nausea read - 'Yoga for Nausea'