Which nursing intervention is most important, for a male client in the oliguric phase of acute renal failure (ARF)?

Limiting fluid intake.
A client in oliguric phase of acute renal failure (ARF) already has low urine output. Fluid intake will increase the overall volume of fluid in the body and this may cause many complications in the body like pulmonary enema.
Encouraging coughing and deep breathing is not an intervention in a client with ARF.

Promoting carbohydrate intake will not do much for the client. Providing pain relief will measures will not change the present condition of renal failure as pain relief do not alleviate the condition. ARF does not cause pain to the client.

Limiting fluid intake

During the oliguric phase of arf, urine output decreases markedly, possibly leading to fluid overload. Limiting oral and i.v. fluid intake can prevent fluid overload and its complications, such as heart failure and pulmonary edema. Encouraging coughing and deep breathing is important for clients with various respiratory disorders. Promoting carbohydrate intake may be helpful in arf but doesnt take precedence over fluid limitation. Controlling pain isnt important because arf rarely causes pain.