A 70 year-old man had been admitted to the ICU 1 week previously after resuscitation of hypoxemic cardiac arrest. The patient had signs of poor neurological outcome, and the ICU team had decided to withdraw life sustaining treatments. The patient’s spouse and children were awaiting a meeting with a junior physician. After introducing himself, the doctor said: “Your husband, your father, will never wake up, he is comatose. We need to stop critical care now. You know, he’s a vegetable.” For the doctor, the family seemed to have understood. The patient died rapidly after extubation and intravenous sedation to treat dyspnea. Three months later, the ICU received a complaint from the family, saying that the meeting with the physician had been a very bad experience. They were deeply shocked by the use of the word “vegetable” to describe their beloved father and husband.

One might say that using the word “vegetable” revealed the tactlessness of an inexperienced medical doctor who just wanted to explain the concept of a coma to a family. We think that this type of metaphor is not only tactless, but could have harmful effects for the patients, families, and caregivers themselves.

Metaphor has a Greek and Latin etymology, stemming from “metaphora”, meaning “transposition”. Indeed, metaphors make it possible to transpose meaning between two words. It is a linguistic process generally used to replace a complex and abstract idea by a concrete and simple image, thus enabling rapid comprehension. Saying “she’s a rock!” about someone signifies that the person is strong and able to withstand life’s events. It is as if language can be used to confer on the person the properties of a rock, such as solidity and hardness.

According to Stewart and Barnes-Holmes who worked on the relational frame theory, construction of a metaphor consists in four different phases. First, two separate equivalence relations are considered in the speaker’s mind (person—capacity to face life’s difficulties; rock—solidity). The relation between rock and solidity is obvious, whereas the relation of equivalence concerning the person is not. Second, formal similarity between these two relations is proposed by the speaker (“This person is a rock”). Third, the listener discriminates the sameness between these two relations. Fourth, in the listener’s mind, there is a transfer of function (solidity) from the obvious equivalence relation (rock–solidity) toward the second equivalence relation (person-solidity, i.e., this person is able to face difficulties). One can observe that a metaphor only illustrates one aspect of the subject. What characterizes a good metaphor is its efficiency, the strength and speed with which a simple image can immediately convey a complex idea.

Let’s go back to the ICU. The physician is in charge of many patients, especially when the doctor on duty is the only doctor in the ICU. Critically ill patients are complex, with multiple organ failure. One might draw a parallel between the use of metaphor, which allows simplification, rapidity, and efficient transfer of meaning, and the work of the intensivist, who requires exactly the same properties: initial simplification of complex cases, rapidity in decision-making and action, and efficiency, enabling the patient to survive with the best possible prognosis.

Metaphors can be helpful for patients. It has been shown that describing the cancer as a “journey” rather than a “battle” was associated with greater acceptance of difficult outcomes.

However, used inappropriately, metaphors can cause misunderstanding and confusion. Some may even be unintentionally harmful. Whereas the “rock” metaphor has positive connotations, the “vegetable” metaphor clearly does not. What does this latter metaphor mean? Which characteristics of a vegetable are highlighted and transposed to the patient, in the doctor’s mind? Obviously, this metaphor illustrates the inability of a comatose patient to think and speak. However, on a deeper level, it also illustrates dehumanization of the patient in the doctor’s mind. Vegetables do not think, have no history, nor do they feel pain or sadness. Dehumanization consists in denying the essence of the other human: intelligence, spirit, language. Dehumanization is a common attitude of humans during intergroup relations, even in the absence of conflict. It is unfortunately quite frequent in medicine, and the risk is particularly salient in the context of highly technical critical care.

The problem is that metaphors are powerful. As written by Gillis and Loughlan, “Metaphors can shape how we conceive the essence of our practice”. In turn, how we think can modify how we act. Speaking of comatose patients using the “vegetable” metaphor is highly problematic. By denying the humanity of a patient, there could be a risk that all precautions have not been taken to identify the exact prognosis of the patient, the best options, or the best way to avoid pain or anxiety during the final hours of life (indeed, vegetables are not anxious or in pain). In addition, the dying patient is not alone, their family is still there, and is very sensitive to the language used. We must make every effort to avoid ambiguity in these highly emotional contexts. Families frequently etch into their memories the words used by the doctor to announce their loved-one’s end-of-life. In this context, the “vegetable” metaphor creates an abyss between the family, who still see the complexity and history of their loved-one, as well as mental pictures of their previous healthy life, and the doctor, who has dehumanized the patient to keep his/her mind free for the remaining patients in the ICU.

Clinicians should be aware of the power of metaphors. They should think of the beneficial and efficient metaphors that can help them when delivering care, and that may help patients and families understand the difficulties and risks. They should also be mindful of the harmful effect of some metaphors, and should teach this important point to their students during formal training in communication. Finally, every practitioner should think about the metaphors, sometimes used unconsciously, that characterize their practice. They might consider reinventing and creating new metaphors that could help them think about things in a new light, and improve their practice of medicine.