Emergency Oxygen Therapy - PowerPoint Presentation

Slide1

Emergency Oxygen Therapy

Is there a problem?

Clinical Case

No. 1

79-year-old female, diabetic, morbidly obese

Admitted with ‘

LVF

’

Overnight ‘

Reduced GCS ?cause

’

15L oxygen via non-rebreathe in situ

ABG showed pH 6.9, pCO2 15.9kPa

normal range 4.5-6.0kPa

Woke up when oxygen removed!

Oxygen prescribed with target SpO

2

88-92%, documented in notes

Following morning on AMU GCS 3/15 and 15L NRB back in situ!

Not a candidate for NIV

→

RIP

Clinical Case

No. 2

75-year-old male, cervical myelopathy (cord compression due to OA)

Admitted with reduced GCS (9/15)

pH 7.1, pCO

2

9.6kPa (respiratory acidosis)

Improved with controlled O

2

24-28%

Treated for pneumonia

Became drowsy again with rising pCO

2

and low RR

Miotic

(small) pupils

Covered in fentanyl patches

Improved once patches removed and naloxone given!

Clinical Case

No. 3

86-year-old female from RH, osteoporosis

Admitted with pneumonia

Asked to see on AMU because of ‘

fitting

’

Hypotensive, myoclonic jerks, bounding pulse

On 10L O

2

via NRB since admission

ABG showed pH 7.23, pCO

2

12.9kPa

Minimal improvement with reduced FiO

2

Not a candidate for HDU or NIV on the respiratory ward

→

RIP

Oxygen —there is a problem!

Published national audits have shown;

Doctors and nurses have a poor understanding of how oxygen should be used

Oxygen is often given without any prescription

If there is a prescription, it is unusual for the patient to receive what is specified on the prescription

Monitoring of oxygen administration is often poor

→OXYGEN IS DANGEROUS

NPSA alert 2009

Emergency Oxygen Use in Adult Patients

BTS Guideline 2009

Prescribing by target oxygen saturation

Keeping SpO

2

within

normal

limits

Target SpO

2

94-98% for most patients

92-98% if >70

Target SpO

2

88-92% (pO

2

6.7-10kPa) for those with or

at risk of

hypercapnic

(high CO

2

) respiratory failure

Aims of Emergency Oxygen Therapy

To correct or prevent potentially harmful hypoxaemia

To alleviate breathlessness

only if

hypoxaemic

Increasing FiO

2

(inspired oxygen concentration) is only one way of increasing overall O

2

carrying capacity of blood:

Protect airway

Enhance circulating volume and cardiac output

Correct severe anaemia

Avoid or reverse respiratory depressants

e.g. morphine

Treat underlying cause

e.g. LVF, asthma

Indications for Emergency Oxygen

SpO

2

<94%

<88% if risk of hypercapnia

Critical illness

e.g. septic shock, major trauma, anaphylaxis, acute LVF

during initial ABCDE

Carbon monoxide poisoning

irrespective of SpO

2

Too much O2

can be harmful…

Risk of hypercapnia (high CO

2

) in selected patients

some patients with chronic hypercapnia are dependent on

hypoxaemia

to maintain respiratory drive

Constriction of coronary arteries

high O

2

levels INCREASED mortality in survivors of cardiac arrest

Constriction of cerebral arteries

high O

2

levels INCREASED mortality in non-hypoxic patients with mild-moderate stroke

Patients at risk of hypercapnia?

COPD

not all patients with COPD —elevated HCO

3

-

on ABG is a useful clue to chronic CO

2

retention

Morbid obesity

OHS and OSA

Neuromuscular weakness

MND, myasthenia, GBS

Chest wall deformity

kyphoscoliosis

Reduced conscious level

Morphine

and other respiratory sedatives

How should oxygen be delivered to…

Critically unwell / severely

hypoxaemic

patients?

h

igh-concentration reservoir / non-rebreathe mask

delivers 60-80% O2 at 10-15L/min

SHORT-TERM

use only

e

nsure bag is filled with oxygen before attaching to patient

DO NOT

turn down oxygen flow below 10L/min

How should oxygen be delivered to…

Most other patients?

n

asal

cannulae

/ specs

c

omfortable, well-tolerated, low-cost and no risk of re-breathing

2-6L/min gives ~24-50% oxygen

concentration actually delivered also depends on patient’s:

tidal volume

respiratory rate

patients with COPD tend to breath disproportionately more oxygen than air with every breath

→ risk of hypercapnia

How should oxygen be delivered to…

P

atients at risk of

hypercapnic

respiratory failure?

Venturi

/ fixed performance masks

increasing oxygen flow does NOT increase FiO

2

accurate between 24-40%

60%

venturi

delivers ~50% oxygen

less affected by tidal volume and respiratory rate (useful in COPD)

Monitoring and Titration of O2

ALWAYS

question whether oxygen is actually required and if so, what is the target saturation range

monitor oxygen saturations frequently / continuously

t

itrate flow rate and / or device up or down until target saturations achieved

use minimum flow rate required

seek to wean off oxygen as soon as possible

NEVER

leave patients on high-concentration O

2

without repeating ABGs

use non-rebreathe masks with flow rates <10L/min

adjust the flow rate through a

Venturi

device without changing the mask

suddenly stop high-concentration oxygen in a

hypercapnic

patient without titrating down first (35%)

BTS National Oxygen Audits

Audit

Year

2008

2009

2010

2011

2012

2013

2015

Oxygen prescribed with a target range?

10%

40%

41%

43%

46%

51%

53%

Percent of drug rounds on which

oxygen was signed for on the

drug chart?

5%

27 %

16 %

20%

20%

21%28%

Percentage of patients within target range where this was prescribed 69%9% of patents at risk of iatrogenic hypercapnia due to being >2% above their target range (despite recognised hypercapnic risk)

How can we improve?

N

urse-led and delivered process —ask yourself these key questions:

Does this patient actually need oxygen?

check saturations on air

oxygen won’t help unless

hypoxaemic

only give oxygen if patient is outside of their target range

if in doubt, ask somebody!

Is oxygen prescribed on the drug chart?

immediately ask a clinician to prescribe if not

Which device is best for my patient

nasal

cannulae

for majority,

Venturi

mask if risk of hypercapnia

What is the target saturation range and is this being achieved?

titrate oxygen up or down until target SpO

2

is achieved

Key Learning Points

Oxygen is a drug —if it’s not prescribed,

DON’T GIVE IT

except in an emergency —like most drugs, oxygen has the potential to kill

Consider risk of CO

2

retention

not just COPD patients

Select best device for delivery

nasal

cannulae

>

Venturi

> non-rebreathe

Frequent monitoring of SpO

2

is required in all patients on oxygen

Titrate O

2

up or down to achieve target SpO

2

94-98%

88-92% if high risk

Avoid

hyperoxaemia

risk of hypercapnia and adverse cerebral / coronary effects

Wean down oxygen at the earliest opportunity once stable

NEVER leave patients on high-concentration O2 for prolonged periods