Tag: fraction of inspired oxygen

Basic Intensive Care Nursing

Intensive Care Nursing Principles include care of the following immediate care aspects: airway safety, breathing, circulation, disability a.k.a. level of consciousness, and exposure. Basic ABCDE assessments of the patient in intensive care increases the patient’s survival rate.

Airway Safety in Intensive Care Nursing

In intensive care nursing, one may observe two types of airways used on patients, both of which are considered to be invasive: an endotracheal tube or a tracheostomy.

An endotracheal tube is usually indicated for patients in respiratory failure who are unable to breathe adequately by themselves, or who are experiencing physiological disturbances, leaving their airway unprotected.

A tracheostomy is a planned procedure indicated for patients in need of a prolonged period of mechanical ventilation.

• Both devices deliver ventilation to the patient through a closed system
• Both devices deliver oxygen from the trachea directly into the lungs
• Both devices have an inflatable cuff near the tube end which provides a seal to avoid air from escaping as well as protection from aspiration of gastric content into the lungs.

Endotracheal Tube

To ensure proper care of an intubated patient, the following measures need to be taken:

Tube Sizing

• tube size is identifiable on the cuff balloon
• tube is usually tied at the lips
• a standard ETT is around 26mm long

Cuff Pressure

• cuff pressure must be checked every 4 hours using a manual device
• cuff pressure must stay between 20-30cm of water
• an over-inflated cuff causes tracheal pressure damage; an under-inflated cuff causes air to escape and the ventilator to sound its alarm for inadequate ventilation
• cuff leaks may happen due to inadequate air in the cuff, damage to the cuff, higher pressure from ventilator exceeding pressure in the cuff, wrong tube fit for the person’s anatomy, or positional leaks on patient movement

ETT Securing

• ensure that the endotracheal tube is secure (unplanned extubation or tube misplacement can jeopardise the patient’s safety)
• note length mark at teeth/lips and document clearly on the nursing report
• ensure tube is tied appropriately with tapes or devices used within your clinical area
• recheck tapes regularly to ensure they do not become loose – only two fingers may be inserted between the patient’s face and ties; if ties become loose, re-tie using a two-person technique to ensure prevention of extubation: one person holds the tube in place whilst the other ties the tapes
• do not tie tapes around the connector at the tube’s end since this can easily become disconnected
• call for assistance if the tube becomes dislodged or if you are concerned

Breathing

Ventilation is the in-out air movement within the lungs’ alveoli during which gas exchange occurs.

During normal breathing, ventilation occurs through negative pressure – energy causes the respiratory muscles to contract, which then lead the respiratory muscles to enlarge the thoracic cavity, creating a negative intra-thoracic pressure, which then results in airflow from atmospheric pressure to enter the lungs…

In simple terms, during normal breathing, air is sucked into the lungs.

Mechanical ventilation uses a positive pressure approach in which a pneumatic system delivers gas into the lungs during the inspiration phase. Following inspiration, the patient exhales to the level of PEEP which is set on the ventilator, thus, expiration happens passively.

In simple terms, during positive pressure ventilation (PPV), air is blown into the lungs.

NOTE: PEEP stands for Positive End Expiratory Pressure, which is the pressure set on the ventilator – pressure set above the atmospheric pressure – aimed to improve oxygenation through the recruit of collapsed alveoli.

Mechanical Ventilation Indications

Respiratory failure can be classed in 2 categories:

1. Type 1: Acute Respiratory Failure
2. Type 2: Hypercapnic Respiratory Failure

NOTE: Occasionally patients may have both.

Type 1: Acute Respiratory Failure

Acute respiratory failure occurs when arterial oxygen level is <8kPa, which is then reflected in a significant drop in the oxygen saturation level – hypoxaemia.

In hypoxaemia, the patient becomes visibly short of breath, with rapid shallow breathing usually accompanied by anxiety and confusion due to insufficient oxygen saturation within the tissues.

Acute respiratory failure typically happens due to conditions affecting gas exchange within the alveoli, such as in COVID-19 which can result in severe pneumonia, commonly bilateral pneumonia affecting both lungs, Acute Respiratory Distress Syndrome (ARDS) which causes the lungs to become waterclogged like sponges, and Pulmonary Embolism.

Type 2: Hypercapnic Respiratory Failure

In hypercapnic respiratory failure, respiratory demand is not met due to inability to breathe in enough air or breathe quickly enough, and so, the patient experiences hypoventilation.

Hypercapnic respiratory failure causes a rise in carbon dioxide along with a decrease in oxygen level; PaCO2 >6.6kPa (50mmHg) with pH of <7.25; pH fall happens due to the rise in carbon dioxide causing acidity in the blood.

Causes of hypercapnic respiratory failure include: upper airway obstruction, epiglottis obstructive sleep apnoea, asthma, bronchospasm, narcotic overdose, chest trauma, flail chest, pleural effusion, pneumothorax, haemothorax, CVA, cranial trauma, Guilllain-Barre Syndrome, and spinal cord injury.

Respiratory Assessment & Physical Examination – Look, Feel & Listen!

Look…

Look at the patient’s chest:

• can you see any obvious deformities?
• is chest expansion equal on both sides?
• are accessory muscles being used?
• is there paradoxical chest wall movement in comparison to the ventilator?

Along with the above observations, take note of the patient’s rate, rhythm, and quality of respirations.

Feel…

Palpate the patient’s chest:

• can you feel both sides of the chest expand?
• can you feel any vibrations within the chest? If yes, this may be an indication of respiratory secretions or fluid – check further by auscultating with a stethoscope

Listen…

• auscultate for breath sounds by pressing the diaphragm side of the stethoscope firmly against the patient’s skin directly
• normal breathing sound a.k.a. vesicular, is soft and low pitched, with inspiration lasting longer than the expiration sound
• crackles are intermittent non-musical sounds which are caused by collapsed or fluid-filled alveoli, most commonly heard on inhalation; crackles may not clear up following coughing or suctioning
• wheezing is a high-pitched musical sound caused by airway narrowing, commonly heard in COPD, Asthma, chest infection or heart failure
• if no chest sounds can be auscultated and chest expansion is absent or limited, call for urgent assistance

Measuring the Effects of Mechanical Ventilation on Gas Exchange

Oxygen saturations and carbon dioxide levels are shown on the monitor and ventilator, as well as on an ABG result strip. Capnography is another way of monitoring carbon dioxide. A CO2 waveform can confirm that the tube is in the right position and that the patient is being ventilated. Flat or dampened waveforms require adjustments.

NOTE: sick patients may be aimed for a higher CO2 than normal – permissive hypercapnia.

Ventilation Risks

• increased pressure in the thoracic cavity can cause lung trauma
• increased risk of ventilator acquired pneumonia – a secondary lung infection; a good precautionary measure is to keep the patient’s head elevated to 30 degrees

Sputum Management

Intubated and ventilated patients cannot cough to clear their own secretions. For this reason, humidification, which is attached to the ventilator and should be checked regularly, is vital. In addition, closed suctioning of the ETT enables secretions to be suctioned out without breaking the circuit to atmospheric pressure.

Related Terminology

• FiO2 – the fraction of inspired oxygen eg. 0.3 = 30% oxygen
• Peak Pressure – airway pressure + alveolar pressure
• PEEP -Positive End Expiratory Pressure
• Tidal Volume – volume of air expired in one breath
• Minute Volume – total volume of air expired in one whole minute

Circulation

As a nurse working in the ICU setting you need to make sure you go through a lot of ‘checks’ prior to starting your shift:

• get a good handover by the nurse who was taking care of your newly assigned patient so that you know the patient’s normal parameter values
• set the alarm limits based on the values given by the handover nurse; set alarms just above the highest and just below the lowest parameters taken during the previous shift
• check all equipment to make sure all is in good working order

Setting alarms related to the cardiovascular system

• heart rate – usually set between 60-100bpm; observe the patient’s ECG trace for a whole minute to know its normal trend
• mean arterial pressure (MAP) – usually set between 60-65mmHg, however, these values are normally based on the patient’s normal limits to allow space for patient movement, coughing, etc
• arterial line trace – observe the A-line trend for a minute so you familiarise yourself with it and be able to notice any differences straight away

Checking Equipment related to the Cardiovascular system

• arterial line – needs to be monitored at all times; related alarms need to be always switched on; check for air bubbles and if any are visible, make sure you remove them; arterial line site needs to be kept clean, dressed with an intact see-through dressing, and kept visible at all times for easy monitoring

NOTE: the Arterial Line is marked with a red line all the way down the side so as to alert healthcare professionals that it is not a regular line.

IMPORTANT: Never inject anything into an arterial line! Special caps are used for arterial lines with the aim of preventing this!

• central venous pressure line (CVP) – certain infusions need to be administered via a CVP line since if injected into smaller veins, these can be destroyed
• check that all lines attached to the patient are clearly labelled with the medication being administered, and dated; this helps identify which line is which, in case a medication needs to be abruptly stopped or disconnected

NOTE: the Central Venous Pressure line may be clear or it may have a blue line running all the way down the side for easier recognition.

• pressure bag + saline bag – the arterial line AND the CVP line should both be connected to a bag of 500ml normal saline 0.9% which sits in a pressure bag; pressure bag needs to be set at a pressure of 300mmHg which is clearly indicated by a green section on the pressure bag gauge
• before zeroing the set, ensure that the bags of saline have enough fluid within them, and that they are up to pressure

• transducer – this needs to be zeroed, sitting approximately in line with the right atrium, so as to ensure that both the arterial line and the cvp line are monitored continuously and accurately; zeroing needs to be done at every change of shift as well as whenever the patient is disconnected
• both the arterial line and the cvp line need to be switched off to the patient, and be open to air, at the correct height, and with the pressure bag blown up, following which ‘zero all’ should be set on the monitor; then, both should be switched back on to the patient, caps should be put back on , and both should be reading correctly

Checking the patient

• check that the patient’s heart rate corresponds to the ECG and arterial line trace and to the radial pulse of the patient
• check that the ECG tabs are correctly placed and have good contact with the patient
• check every line insertion site for any signs of infection or migration
• re-check any significant heart rate change with a manual pulse, blood pressure output and a 12 lead ECG
• check the patient’s limbs and note capillary refill time of all four
• check for skin pallor, warmth, sweating, dry skin, wounds, and bleeding
• check the MAP is reading adequately and whether it needs any fluids or drugs to maintain it
• check the patient’s temperature: >39 degrees celsius needs to be taken care of; on the other hand, a patient can easily become cold in an ICU setting…avoid hypothermia – keep your patient warm!
• ASK FOR HELP IF IN DOUBT AT ANY TIME!

NOTE: In the ICU setting, 5-lead ECG monitoring is used!

Check Urine Output

• a urinary catheter is inserted in every sedated and ventilated patients
• an average person’s urine output should be about 0.5ml/kg/hr; an inadequate blood pressure may later lead to a decrease in urine output, thus, check urine output every hour
• a patient with a low blood pressure and poor urine output may be commenced on inotropes
• common inotropes include Noradrenaline, Adrenaline, and Metaraminol

Inotropes:

• are calculated in mcg/kg/min and titrated according to patient parameters to maintain an adequate MAP
• should be administered through a central line
• use should be accompanied with patient monitoring through an arterial line
• are short-acting, thus, should be set to infuse continuously without running out; if left empty, patient’s blood pressure may drop dangerously low, possibly leading to a cardiac arrest
• IV fluid boluses may also be prescribed, though usually, this is done more in other ward settings

Electrolytes

• electrolytes which have a direct effect on the heart’s conduction, contraction and rhythm need to be closely monitored in intensive care nursing
• potassium level should be >4 – 5.5mmols/L
• magnesium level should be >1.0mmols/L
• phosphate level should be >0.7mmols/L

Disability

Sedating the patient – why?

Sedation level is always decided by the ICU consultant. Reasons for patient sedation include:

• ventilation facilitation
• anxiety relief
• acute confusion management
• treatment implementation
• diagnostic procedures
• reduction of tachycardia, hypertension, or raised intracranial pressure

Commonly used Sedative drugs

• Propofol – anaesthetic agent (negative inotrope)
• Morphine – opiate
• Midazolam – benzodiazepine
• Fentanyl – synthetic opiate
• Remifentanyl – short half life
• Atracurium – muscle relaxant

The Non-Sedated Patient

• assess and document the non-sedated and awake patient using the GCS or the AVPU scale to find out the patient’s level of consciousness and current mental state
• assess and document the patient’s pupillary size and reaction
• identify changes within the patient’s neurological state; if a patient becomes newly confused or difficult to wake up, check for any respiratory issues or medical condition deterioration

The Sedated Patient

• assess the sedated patient using the GCS; include pupillary size and reaction in your assessment and documentation
• document at which level is your patient sedated using the Richmond Agitation Sedation Scale (RASS)
• assess patient at the beginning of your shift; continue performing assessments throughout your shift especially since the necessity for patient sedation level may change

NOTE: always check thoroughly syringe drivers with sedation, including rate and time; ensure replacement syringes are ready to be replaced prior to stopping. Sedation which is abruptly stopped may lead to patients waking up frightened and disoriented, leading to unplanned extubating or high levels of distress and anxiety!

Glucose Level Check

Whilst a patient may not be diabetic, one may still be on insulin in Intensive Care Nursing. This is because in ICU, patients often require an insulin infusion so as to keep their blood glucose level between 4-10mmols.

Thus, it is important to check the patient’s blood glucose levels frequently as per local guidelines, especially since in sedated patients, noticing hypoglycaemia is quite difficult.

Pain Assessment

Pain assessment is vital in intensive care nursing, especially since it may be a good indication of a newly evolving critical condition such as a Myocardial Infarction or an infection.

If a sedated patient exhibits physical stress responses such as an increased heart rate, blood pressure or agitation, consider pain as a possible culprit. A good Critical Care Pain Observations Tool (CPOT) may be used to assess pain in sedated patients. This considers the following aspects:

• facial expression
• body movements
• ventilator compliance
• muscle tension

If pain is suspected, analgesia should be administered. Whilst all ventilated patients are already on sedation and analgesia, an increased rate or a bolus may be considered, followed by a reassessment to check for improvement.

Exposure

Nutrition

In intensive care nursing, the patient should ideally be fed early. If awake and extubated and can eat and drink, assist in doing so. Remember that invasive lines and air mattresses can restrict patient mobility, and some assistance can go a long way!

Following intubation or tracheostomy, a patient needs to undergo a swallow assessment to ensure oral intake is advisable. At times, a nasogastric tube or jejuno tube may be indicated.

Positioning needs to be checked well whenever a new shift is taking over, as well as before oral intake is administered:

1. note tube position and compare current length with the previously documented length
2. ensure tube is well secured so as to prevent migration; change adhesive holder if necessary
3. checking pH of patients in intensive care nursing may be misleading; aspirate gastric contents every 4 hours and replace or discard as per local policy
4. to help with absorption, motility agents may be prescribed
5. tube feeding prescriptions are based on body weight and caloric and electrolyte needs; electrolytes, magnesium and phosphate replacement is usually prescribed together
6. cartridge may need to be changed every 24 hours
7. new lines should always be labelled with date and time of change

If enteral feeding fails, total parenteral nutrition is usually considered. TPN is administered via a PICC line or Central Line through a specific lumen – a white port. Medications are not administered via the same line.

NOTE: TPN is lipid based and so it requires strict asepsis when lines and bags are changed. New lines need to be labelled clearly with the date and time of change.

Nausea & Vomiting

An abdominal assessment needs to be performed on the patient in intensive care nursing …

LOOK at the shape and for distension, masses, ascites, prominent veins, bruising, scars, drains, or stomas.

LISTEN for bowel sounds using your stethoscope over the right lower quadrant.

FEEL and assess for localised or radiating pain and masses.

Bowel Assessment

• check the last documented bowel action – patients in the Intensive Care Setting are prone to becoming constipated due to reduced bowel motility
• administer any prescribed aperients (drugs to help with constipation) which are usually started early on in this setting to promote regular bowel movements
• promote dignity especially in the case of incontinence
• take positioning into consideration – assisting the patient with a hoist to a more natural defecation position can help conscious patients
• if patient experiences uncontrolled diarrhoea, rectal tubes may be indicated to protect the skin and to measure fluid loss
• record frequency and consistency

Assessing for Venous thromboembolism (VTE)

Patients in the intensive care setting are often provided with intermittent compression boots eg. flowtron, to help stimulate blood flow to deep veins, so as to help prevent thrombosis. Such devices need to be removed at least once per shift so the underlying skin is thoroughly assessed.

Mouth Care in the ICU Setting

Mouth care in the intensive care setting provides the patient with comfort. Additionally, it helps prevent Ventilator Associated Pneumonia. Toothpaste and baby toothbrushes are used twice daily. Ideally, water is given every 4 hours, and vaseline is applied to the patient’s lips every time.

Eye Care in the ICU Setting

Sedated patients are not able to blink, which leads to an increased risk of corneal sores. Use recommended eye drops as per local policy for this reason. Check the patient for redness, pus, dryness, and Scleroderma. Use eye drops and lacrilube.

Patient Skin Care

• check for skin breakdown, redness, blistering surgical sites, existing pressure sores, wounds, dressings, or rashes; if needed, change the type of mattress they are currently on
• encourage position changes or move sedated patients regularly to avoid formation of pressure sores
• check the skin beneath flotrons or devices to avoid thrombosis at least when starting your shift
• check the NGT for any markings onto the nostrils
• check ETT and holders, repositioning / pressure alleviating devices; check tapes’ last change and note any ulcerations, bleeding gum or loose teeth
• change saturation probe position at least every 2 hours
• check for any lines or drain catheters underneath the patient
• minimise shear and friction damage whilst handling the patient
• ensure no creases are on the bed sheets since these may cause pain and sores
• change any IV lines and feeding tubes as per local policy

Reference

Critical Care Outreach Team (2020). Basic Principles of Intensive Care Nursing. Royal Berkshire NHS Foundation Trust. Retrieved from https://www.baccn.org/media/resources/Basic_principles_of_Intensive_Care_Nursing.pdf on 18th October 2022

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