need to know Flashcards
(9 cards)
Normal flow volume loop
PEFR at top
TLC. on the line at left
RV on the line at right
and FVC is the difference
COPD/ emphysema flow volume loop
Leftwards, higher TLC, higher RV, decreased PEFR, coving of expiratory curve
Restrictive lung disease flow volume loop
Lower PEFR, rightwards TLC, less RV, and circular
Fixed upper airway obstruction flow volume loop
Decreased PEFR, Increased RV an adjust flat inspiration and expiration limbs
Nocturnal hypoventilation
Breathing during sleep differs from the awake state. Can be caused by obesity.
For most people the change in alveolar ventilation is insignificant (2% baseline O2 sat
drop), however for those patients whose daytime respiration is restricted nocturnal
hypoventilation can be catastrophic.
These patients can be considered as 2 groups
1) Patients with lung parenchyma involvement in their disease. e.g. COPD, emphysema
and Fibrosing Alveolitis.
2) Patients with extra-pulmonary restriction - ‘a bellows problem’
e.g. Kyphoscoliosis, muscle disease, childhood polio.
It is this second group who are best treated with NIPPV (Nasal Intermittent Positive
Pressure Ventilation)
Untreated these patients are unable to maintain normal O2 and CO2 levels during
sleep. (especially REM sleep when huge falls in O2 sat and large CO2 rises can be
seen.) Their daytime breathing is often barely sufficient to maintain normal blood
gases and each night they are plunged into respiratory failure.
(NB THIS IS TYPE II RESPIRATORY FAILURE AND IS NOT APPROPRIATELY
TREATED WITH O2 THERAPY. THESE PATIENTS BREATH PRIMARILY ON
HYPOXIC DRIVE. INCREASING THEIR O2 REDUCES RESPIRATORY DRIVE
LEADING TO FATAL RISES IN CO2)
Eventually the patient will be unable to ventilate themselves to normal during the day
and will enter long term ventilatory failure (often precipitated by infection.)
The patient’s lungs are relatively normal, the problem is one of alveolar ventilation. The
effective lung volumes are small and dead-space occupies a disproportionate
percentage of each breath.
NIPPV is designed to counteract the hypoventilation associated with sleep.
Each breath is augmented by the ventilator to wake or better levels by pumping air into
the lungs under pressure. This often means that previously unventilated lung volume is
recruited.
The recent increase in the numbers of patients with COPD treated in the acute
exacerbative phase with nasal ventilation has seen the widespread use of Bi-level
ventilators (most commonly the BI-PAP or VPAP). These machines produce a high
inspiratory pressure (typically up to 25 – 30 cm H2O) with a lower expiratory pressure
(similar to PEEP). These machines are most commonly used in spontaneous mode
where the patients more variable respiratory rate may be imposed on the ventilator
rather than trying to ‘force’ a patient to breath in a regular imposed pattern during the
exacerbative state. The primary aim is to support the patients breathing during the
exacerbation and so reduce in-patient time and reduce the need for ICU admission with
the consequent problems of weaning patients from intubated ventilation.
Upper airways resistance syndrome
The compliance of snorers is not as good as that of SAHS patients. (? due to less sleep
disruption - This leads to the critical question of what constitutes sleep disruption and
what is the best way to measure this? Some snorers complain of significant symptoms
whereas others have no complaints.)
Those snorers with significant symptoms when studied over night are usually found to
have upper airways resistance syndrome (UARS). This is similar to SAHS but each
respiratory irregularity is not associated with a 4% drop in oxygen saturation. The
events are however terminated by arousal causing sleep disruption
- lower BMI patients
Upper Airway Resistance Syndrome (UARS) can be treated with lifestyle changes, oral appliances, and in some cases, surgery. The primary treatment is often continuous positive airway pressure (CPAP), which helps to maintain an open airway during sleep. Other options include mandibular advancement splints (MAS) to reposition the jaw, and in severe cases, surgery to correct anatomical issues in the upper airway.
Treatment Options:
Lifestyle Changes:
Weight loss, if overweight, can help reduce narrowing in the throat. Sleeping on your side or front may also be helpful.
CPAP Therapy:
CPAP is a common and effective treatment that involves wearing a mask during sleep that delivers a continuous stream of pressurized air to keep the airway open.
Oral Appliances:
MAS and other oral appliances can be used to reposition the jaw and tongue, opening the airway and reducing resistance.
Surgery:
Surgical procedures to correct anatomical issues in the upper airway, such as nasal or palatal surgery, may be an option for those who don’t tolerate CPAP or other treatments.
Orthodontic Treatments:
Functional orthodontics can address dental malocclusion, a common factor in UARS.
Other Treatments:
Other oral appliances like tongue retaining devices and soft palate lifters may be used.
Normal blood gas values
Normal values
PO2 10.0 – 13.3 kPa
pH 7.35 – 7.45
PCO2 4.6 – 6.0 kPa
Base Excess (BE) -5 – 5 mmol
Standard Bicarbonate (HCO3) 20 – 30 mmol
Difference between type 1 and type 2 respiratory failure?
Type 1 respiratory failure, also known as hypoxemic respiratory failure, is characterized by low blood oxygen levels (hypoxemia) with normal or low carbon dioxide levels (normal or low PaCO2). Type 2 respiratory failure, also called hypercapnic respiratory failure, involves both low blood oxygen and high carbon dioxide levels in the blood (hypercapnia).
if patient is obese ? obesity hypoventilation syndrome. Patients with particularly severe nocturnal hypoventilation are also likely to present with hypercapnia on blood gases due to the significant drop in ventilation overnight.
