These same authors usefully define the terminology they employ and give approximate time-spans for each:
“Delirium is defined by the presence of disturbed consciousness (reduced clarity of awareness of the environment with reduced ability to focus, sustain, or shift attention) and a change in cognition (such as memory deficit, disorientation, or language disturbance) or the development of a perceptual disturbance that is not better accounted for by a pre-existing, established, or evolving dementia. Emergence delirium occurs on emergence from anaesthesia and sedation, with no lucid interval, and lasts approximately 30 minutes. Postoperative delirium lasts hours or longer, with or without lucid intervals. Postoperative cognitive decline refers to a more subtle cognitive impairment noted on neuropsychological tests that typically assess attention and memory.”
They regard postoperative delirium as the most severe. They describe the phenomenon as “brain failure” and draw an analogy with failure of any major organ – e.g. kidney or liver.
There is no universally accepted mechanism thought to be responsible for the development of postoperative delirium. Very often there is a period of normality, followed by a dramatic change. Patients may become very lethargic and uncooperative or exceedingly agitated, aggressive and violent. They are at risk of lethal self-harm at this stage. In our view this is a medical emergency and help is required immediately. Signs include fluctuating levels of consciousness, inattention, disorganised thinking, and perceptual disturbances such as hallucinations and delusions.
Some factors are thought to predispose to the development of postoperative delirium. In one prospective study of the incidence of post operative delirium in an intensive care unit preoperative benzodiazepines, breast and abdominal surgery and surgery of long duration were found to be risk factors for emergence delirium. Thankfully in this study the incidence was uncommon. Sixty -four (4.7%) patients developed delirium in the PACU. Other prospective studies have found a higher incidence (20% +-). Other authors report incidence rates in medical inpatients as high as 42%. Other studies have failed to demonstrate benefit from identifying high-risk patients preoperatively. Introducing the delirium prevention protocol did not reduce delirium incidence although it was good at identifying those at greater risk. In this same study, the use of prophylactic medication (haloperidol) in high-risk patients failed to reduce the incidence of delirium prevention protocol did not reduce delirium incidence although it was good at identifying those at greater risk. In this same study, the use of prophylactic medication (haloperidol) in high-risk patients failed to reduce the incidence of delirium.
The doctors and nurses may not know your relative as well as you will, or may not even have met them before (new shift). You may have noticed some of these initial signs or changes in your relative before anyone else. It is important to bring your observations to the attention of the nurses or doctors.
Where possible, a new history should be taken. If the patient has periods of lucidity and insight then the history may be obtained from the patient themselves but very often the next of kin, relatives or accompanying person are the best source of information. This information should include discrete questions about drugs, alcohol use, other illnesses especially diabetes, head injury and previous mental state. It is likely that these lines of personal medical history will not have been explored previously if, for example, a patient’s initial purpose for admission to hospital had been for a joint replacement in the knee. Do not be offended by these questions, some of which may be very personal.
A score of less than 6 suggests impaired cognition. Having diagnosed impaired cognition it is important to identify the cause and start appropriate treatment. Depending on the cause the period required to recover once treatment is started may vary between hours to months.
Remember however, a good doctor will not be offended by a request for a second opinion or referral to a specialist experienced in general or internal medicine. You always have the right to ask.