Kao et al[3] conducted a retrospective cohort study to investigate in-hospital mortality and long-term survival rates in critically ill patients with AKI or ESRD receiving renal replacement therapy. This study found that overall in-hospital mortality was 66.5% and there was no significant difference in mortality rates between AKI and ESRD groups (adjusted odds ratio: 0.93; 95%CI: 0.84-1.02)[3]. Hypertension was found to be a high-risk factor for in-hospital mortality in patients with AKI while older age, chronic liver disease and history of cancer were found to be independent risk factors for in-hospital mortality in both AKI and ESRD groups[3]. In addition, older age, coronary artery disease, and ICU admissions were found to be risk factors in AKI patients for long-term dialysis dependence[3]. In another study, Bagshaw et al[4] investigated risk factors and outcomes associated with critically ill septic AKI patients in ICU. Compared to non-septic AKI group, septic AKI group had greater severity of illness (P = 0.0001), hypotension (P = 0.0001), tachycardia (P = 0.0001), worse lung function measures (P = 0.0001), higher white cell counts (P = 0.0001) and significant acidemia (P = 0.0001)[4]. Also, septic AKI group was associated with a higher crude mortality rate in the ICU (19.8% vs 13.4%, P ≤ 0.001) and in the hospital (29.7% vs 21.6%, P < 0.001) compared to non-septic AKI group[4]. Furthermore, a recent prospective cohort study involving septic AKI patients undergoing dialysis in the ICU found that norepinephrine use, hepatic failure, medical condition, blood lactate, and pre-dialysis creatinine level were associated with early mortality (seven days)[5].

Palliative care should be considered for all high-risk AKI patients in the ICU determined by the presence risk factors associated with poor outcome or high mortality rates as discussed earlier. Three palliative care models have evolved over two decades with an aim to improve quality of care and reduce suffering in the ill patients[6]. These models of care may be considered in the ICU setting for AKI patients as appropriate.

Conventional model of care: This is also called as the traditional dichotomous model of palliative care where ICU patients receive curative or disease-specific care for AKI till it fails following which palliative care will be initiated[7]. This dichotomous model offers AKI patients either curative/disease-specific care or palliative care but not both simultaneously, which leads to a sudden transition from curative to palliative care without enough transition time (Figure 1)[6,7]. The Conventional model of care is suitable for young AKI patients in the ICU without high-risk factors associated with the poor outcome such as septic shock, acidemia, hypertension, coronary artery disease, chronic liver disease and history of malignancy. Given higher resolution rates in this patient population, curative or disease-specific therapy is given first for the management of AKI till it is unsuccessful and then palliative care is initiated.

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Figure 1 Conventional model of care. Patients receive curative or disease-specific care till it fails following which palliative care will be initiated.

Comprehensive model of care: This is also called as the overlapping model of palliative care where ICU patients receive both curative or disease-specific care for AKI and palliative care simultaneously (Figure 2)[7]. Although this model of care is dichotomous, it offers both curative/disease-specific and palliative care simultaneously to the patients with a gradual increase in palliative care over time and slow withdrawal of curative/disease-specific care[6,7]. However, both of these dichotomous models of care have the disadvantage of providing one model of care at the cost of the other[6]. The Comprehensive model of care is suitable for older AKI patients in the ICU with multiple comorbid conditions in addition to the presence of high-risk factors for the poor outcome such as septic shock, acidemia, hypertension, coronary artery disease, chronic liver disease, history of malignancy and history of prior ICU admissions. Due to the poor outcome and higher mortality rates in this patient population, concurrent initiation of palliative care early in the course of medical management helps to prevent and relieve suffering from pain and other physical, psychological, emotional and spiritual distress[7].

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Figure 2 Comprehensive model of care. Patients receive both curative/disease-specific and palliative care simultaneously with a gradual increase in palliative care over time and slow withdrawal of curative/disease-specific care.

Conceptualization model of care: This is also called as the individualized integrated model of palliative care where ICU patients concurrently receive both palliative care and curative or disease-specific care for AKI, but individualized to suit the needs of the AKI patients and family members[7]. In this model of care, palliative care extends beyond the death of the patient to include bereavement care for the family members[7]. In addition, the intensity of palliative care varies based on the needs of the patient or family member during the course of management[7]. Conceptualization model of palliative care is best suited for poor prognostic AKI patients in the ICU with multiple comorbidities and multi-organ failure. This model of care classifies all the interventions and options of care based on goals allowing more flexible management[6]. Once the palliative care is consulted for the impending death of a family member or friend that entails life-changing events and dynamics, the conceptual model helps in supportive intervention to educate family caregivers about stress coping strategies and creates a perception that they have necessary skills to confront problematic situations. (1) Cure-seeking care: Aim to eliminate the underlying disease/medical problem with medical treatment[6]. For example, treatment of sepsis, hypotension, acidosis, electrolyte imbalance, and underlying connective tissue and immunological disorders in AKI patients; (2) Life-extending care: Aim to prolong life in chronic disease states with the help of medical treatment while also enhancing the quality of life[6]. For examples, AKI patients with long-term dialysis dependence; (3) Quality of life and comfort maximizing care: Aim to improve function, reduce suffering and enhance the quality of life in AKI patients in the ICU, and these interventions may also prolong life[6]; (4) Family supportive care: Aim to address the grief and emotions of the family members from the time of diagnosis to past death[6]. The key variables that should be considered for supportive care interventions for family members are[8]; preparedness of the caregivers for the tasks and demands of the role, mastery to manage stress, competence to adapt more quickly to the situation, self-efficacy to manage a situation with coping behaviors, social support to the caregivers, positive emotions to reframe the stressful situations in a positive way, optimism of caregivers to neutralize some potentially negative aspects of caregiving[8]; (5) Healthcare staff supportive care: Aim to address the grief and emotions related to the management of these AKI patients in the ICU[6].

Patel et al[9] described outcomes and decision-making process for nephrologists in the management of AKI in the ICU setting. Expected outcomes and prognosis for patients with AKI remain poor with the mortality rate of 28%-90%[10]. The highest prognostic indicators for mortality were concomitant multi-organ failure, mechanical ventilation, liver-failure, and malignancy[9,11,12]. These prognostic indicators aid physicians to offer palliative care at an appropriate time in this patient population. Furthermore, the use of the RIFLE (Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease) criteria to establish predicted mortality was around 80%-85% and that, while not perfect, could still be an acceptable tool to help establish the prognosis for AKI patients in the ICU[9,13]. However, in those patients who survive, 70%-90% have a recovery of kidney function[12,13]. Hence RIFLE criteria can be considered when making clinical decisions regarding the discontinuation of dialysis in AKI patients[12,13]. The Renal Physicians Association/American Society of Nephrology (RPA/ASN) guideline, Shared Decision-Making in the Appropriate Initiation of and Withdrawal from Dialysis, helps to establish general recommendations in certain situations in which dialysis may be discontinued[14]. These situations are: (1) a patient with full capacity for judgment who asks for dialysis to be discontinued; (2) a patient who lacks capacity but previously expressed a desire not to continue dialysis; (3) a patient without capacity but power of attorney asking to withdraw dialysis; (4) a patient who has irreversible, profound neurological impairment; (5) a patient who has a terminal illness (severe cirrhosis, end stage pulmonary disease, advanced stage of cancer) with a life expectancy of ≤ 6 mo. In these situations, it is appropriate to consult palliative care and develop a plan to proceed with the discontinuation of dialysis.

Advance directives also play an important role in clinical decision-making. The presence of an advance directive gives clinicians a guide as to what patient wishes are, and those decisions should be respected[9]. However, one study involving cancer patients in the ICU demonstrated that the presence of an advance directive did not alter decision-making regarding life-supporting interventions[15]. This alone is concerning; however, this issue becomes more complex when it is considered that most advance directives typically do not directly address acute dialysis in the setting of AKI. Nephrologists are often left without a guide for advance directives to determine the continuity of care in this specific setting.

Cost is another factor, which must be considered in these patients. The SUPPORT trial helped to establish the cost-effectiveness of AKI treatment involving 490 patients[1]. This trial determined that overall cost of renal replacement therapy per quality-adjusted-life-year in AKI patients in the ICU was $128200 with $274100 for patients in worst prognostic group and $61900 for patients in the best prognostic group. However, it surpassed the cost-effective limit of $50000 per quality-adjusted-life-year[1]. In another study by Gopal et al[16], the outcomes of 85 survivors of multi-organ failure who required the use of renal replacement therapy in ICU found that the cost of each year of survival was $50000, and the majority of survivors felt that their treatment was worthwhile and their quality of life was satisfactory. With a high mortality rate of up to 90% for ICU patients with AKI[10], the ethical principle of justice and the equitable distribution of resources must be considered when treating these patients. In these situations, a palliative care consult would provide a more cost-effective treatment apart from better symptom management and a better quality of life.