IICP (Increased Intracranial Pressure)

• ICP: (intracranial pressure)is defined as the pressure within the craniospinal compartment(skull), a closed system that comprises a fixed volume of neural tissue, blood, and cerebrospinal fluid(CSF)
• The upper limit of normal ICP in adults and older children is given as 15~20mmHg, although the usual range is 5~15mm Hg. Transient physiologic changes resulting from coughing or sneezing often produce pressures exceeding 30~50mm Hg, but ICP returns rapidly to baseline levels. When ICP increases to more than 20mmHg, the patient needs immediate medical treatment. (1mmHg=1.36cm H2O)
• The human skull is very hard and it is limited in how much it can expand when something changes inside. There are 3 structures inside the skull that can increase the ICP: the brain, the CSF, and the blood within the brain. The CSF flows around the brain and down through the spinal cord. 

What are some factors that influence ICP?

• body temperature
• Oxygen status, especially CO2 & O2 levels
• Body position: Head elevation 30~35 degree, head midline, no flexion neck or hips
• arterial and venous pressure
• anything that increases intra-abdominal/ thoracic pressure ( vomiting, bearing down)

Monro-Kellie Hypothesis: understanding of how the body tries to compensate when our body is experiencing increased ICP. The Monroe-Kellie hypothesis states that the sum of the intracranial volumes of blood, brain, CSF, and other components is constant, and that an increase in any one of these must be offset by an equal decrease in another. 

 

The body will try to move the CSF somewhere else in the brain or into the spinal or it can affect the cerebral arteries to perform vasoconstriction in order to decrease cerebral blood flow (the amount of blood going to brain tissue)

 

However, the body can only do this up to a certain point and if the ICP continues to buid, it will get to a point the body will start to make things worse => Cushing’s Triad. 

 

Cerebral Perfusion Pressure (CPP): pressure that pushes the blood to the brain

• normal CPP is 60~100mmHg

when CP falls too low, the brain is not perfused and the brain tissue dies (ischemia)

 

How to calculate CPP?

CPP=MAP - ICP 

          MAP = [systolic + (diastolic ^ 2)] / 3

 

How is Monroe-Kellie Hypothesis related to Cushing’s Triad?

• Monroe-kellie Hypothesis explains the compensatory relationship among the structures in the skull that play a role with ICP (Bood, CSF, Brain). If the compensation doesn't work well it undergoes Cushing's Triad. 
• Cushing’s Triad: systolic BP increase, pulse decrease, respiration decrease. 

Causes/ Risk factors of increased ICP:

• brain injury
• high CSF
• bleeding
• Hematoma
• Hydrocephalus

Clinical Manifestation ( signs & symptoms ) - MIND CRUSHED

• Mental status changes: restless, confused, responding to question
• Irregular breathing: cheyne -stokes(rapid breath and apnea)
• Nerve change to optic & oculomotor: (double vision, swelling of optic nerve=papilledema, unequal pupils, abnormal doll’s eye, oculocephalic reflex.

  

• Decerebrate or Decorticate posture or Flaccid

• Cushing’s Triad: increase SBP- widening pulse pressure ( SBP increase, DBP decrease), HR decreased, RR decreased (abnormal)
• Reflex & Babinski
• Unconscious
• Seizure
• Headache
• Emesis (vomiting without nausea)
• Deterioration of motor function: hemiplegia(one side paralysis)

Nursing Interventions: “PRESSURE”

Focus on preventing further increasing of ICP and Monitor ICP

• Position HOB: 30~35 degree, head midline, no flexion neck or hips
• Respiratory: prevent Hypoxia & hypercapnia, mech-ventilation (PaCO2 30~35), suction prn( no more than 15 sec), O2 level, keep PEEP low
• Elevated temperature prevention: damage to hypothalamus, infection, dehydration, etc. monitor temp=>unconscious? antidiuretics, cool bath, remove extreme blanket, decrease room temp. cool blankets. 
• Symptoms to monitor: neurological symptoms/ GCS (15 normal, less than 8 comatose, 3-unresponsive), ventriculostomy, external ventricular drain.(>20mmHg)
• Straining activities should be avoided: vomiting/ sneezing, coughing, valsalva, keeping the environment calm & avoiding restraints. 
• Unconscious patient Care: avoid over sedating, lung sounds, immobile (skin breath, nutrition, renal sterns, constipation, ROM, eye care, GI tubes, blood clots)
• Rx: medications: 

Barbiturates help decrease brain metabolism -> helps to decrease ICP

Use of Vasopressors/ IV fluids/ antihypertensives to maintain SBP at >90 but <150 => maintain the MAP => maintain CPP (MAP: 60~100)

Anticonvulsants for seizure precautions

Hyperosmotic drugs - Mannitol (concentrated sugar)

• Edema management - Mannitol ( concentrated sugar) 

            Mannitol draws water that is pooling in the brain into the blood 

            ㄴthis helps to dehydrate the brain and tissue swelling

            ㄴ this puts patients at risk for fluid volume overload initially

            ㄴ Need to monitor FF and pulmonary edema

            ㄴ list to lung sound and monitor HR

           Mannitol is filled through the Glomerulus

             ㄴWater, and electrolytes (sodium and chloride) will not be reabsorbed and             

                  secreted out of the body

             ㄴShould not bemused on patients who are anuric or have cerebral hemorrhaging

             ㄴNurse needs to monitor for s/s of thirst and dry mouth

             ㄴ Monitor renal functions

             ㄴMonitor urinary output and electrolytes