intro to critical care- clin med

clin med 1

ways to deliver oxygen to pts

nasal cannula

simple face mask

venturi mask

mid flow nasal cannula

non-rebreathing mask

HiFlow

CPAP

BiPAP

ventilators

nasal cannula

ways to deliver oxygen to pts

nasal cannula

simple face mask

venturi mask

mid flow nasal cannula

non-rebreathing mask

HiFlow

CPAP

BiPAP

ventilators

nasal cannula

if the NC is set to < 4 lpm . . .

humidity is not required

a simple face mask delivers

35-50% O2 at flows of 6-10 lpm

a simple face mask is used for

short term use only

what can you not use a simple face mask at?

flows of less than 6 lpm

a simple face mask does not require

humidity

simple face mask

a simple face mask can be used for delivery of

inhaled medications

• bronchodilators, steroids, narcan

venturi mask

venturi masks deliver

24-50% O2 depending on which connector is used

a venturi mask is an accurate way to

deliver O2

venturi masks are ideal for

CO2 retainers or hypoxic drive pts

when using a venturi mask be sure to

ensure connectors are not covered

never use bubbler humidifier

mid flow nasal cannula

a mid flow nasal cannula

provides higher fiO2 than traditional NC

mid flow NC

O2 flow 7-15 lpm

humidified

non-rebreathing mask

NRB delivers

80-100% O2 at flows of 12-15 lpm

with a NRB, the reservoir bag must

not collapse during inspiration, if it does you should increase the flow

with a NRB you should

never humidify

do not remove one-way valves

HiFlow

HiFlow delivers the

highest percentage of O2

how does HiFlow work?

oxygen is blended with compressed air up to 50 psi

gas is heated to 37 C and humidified to near 100%

cannula should occlude approx. 50% of nares

normal pH in an ABG

7.40 (7.35-7.45)

normal PCO2 in ABG

40 (35-45 mmHg)

normal HCO3- in ABG

24 (22-26 mmol/L or meq/L)

normal Na+

135-145 mEq/L

normal K+

3.5-5.0 mEq/L

normal Cl-

96-109 mEq/L

normal total CO2

24-30 mEq/L

if pH is less than 7.4

acidosis

if pH is greater than 7.4

alkalosis

if acidotic and CO2 is increased

respiratory

if acidotic and CO2 is decreased

metabolic

if alkalosis and CO2 decreased

respiratory

if alkalosis and CO2 increased

metabolic

if pCO2 and Bicarb move in the saME direction, it’s

primary MEtabolic

if pCO2 and Bicarb more in a diffeREnt direction, it’s

primary REspiratory

Aa Gradient

normal Aa gradient is

Normal= age/4 + 4

CPAP is a

fixed positive pressure throughout the respiratory cycle

CPAP appears to be more

effective in reducing the need for tracheal intubation and possibly mortality in pts presenting with ACPE

CPAP is the first line tx for

OSA

BiPAP

when the ventilator delivers different levels of pressure during inspiration (IPAP) and expiration (EPAP)

BiPAP ventilation appears to be more effective in

reducing mortality and the need for tracheal intubation in pts with an acute decompensation of COPD

CPAP/BiPAP indications

• respiratory distress secondary to suspected CHF

• acute cardiogenic pulmonary edema

• pneumonia

• COPD (asthma, bronchitis, emphysema)

• OSA

CPAP/BiPAP contraindications

• unconsciousness

• suspected PTX

• inadequate respiratory drive

• shock/hypotension

• chest wall trauma

• persistent N/V

• active upper GI bleed or hx of recent gastric surgery

CPAP/BiPAP problems related to pressure

• sinus pan

• gastric insufflation

• PTX

CPAP/BiPAP problems related to airflow

• dryness

• nasal congestion

• eye irritation

CPAP/BiPAP other complications

• claustrophobia

• air leaks from poor mask seal

• pressure sores at nasal bridge or face

CPAP settings

• pts suspected with ACPE set to 10 cm H2O

• oxygen should be titrated based on PCO2, PaO2, and titrated to the pt SpO2 @ bedside with a target of 88-92%

BiPAP settings

• For patients receiving BiPAP start with an IPAP of between 10-15cm H2O (generally not to exceed 25cmH2O), and EPAP of between 4-7cm H2O.

  • Default 10/5cmH2O

• This pressure can be titrated up or down depending on the combination of clinical effect as well as patient comfort.

• Failure to improve oxygenation should prompt an increase in fractional inspired oxygen and EPAP.

  • Oxygenation

• Failure to improve the hypercarbia should lead to an increase in IPAP.

  • Ventilation

  • Improved ventilation with greater IPAP-EPAP

what is preferred for acute exacerbations of COPD?

BiPAP

interventions that decreased mortality

Noninvasive Ventilation

Mild hypothermia after cardiac arrest (32-34C)

Prone Positioning in ARDS

Low tidal volume ventilation in ARDS

TXA in patients with or at high risk of traumatic hemorrhagic shock

Daily interruption of sedatives in critically ill patients

Albumin in cirrhotic patients with SBP

Assist Control v. PRVC/VC + ventilators

• minimize risk of barotrauma d/t high pressure peaks

• guarantees delivery of desired tidal volume

• decelerating flow pattern may provide better distribution of ventilation and oxygenation

• can better meet pt’s inspiratory flow demands

when doing AC/PRVC ventilators what do you need to determine the settings for/what parameters?

RR

tidal volume (Vt)

PEEP

FiO2

inspiratory time and flow trigger

with a NC, the O2 concentration will vary with

pt breathing patterns

NC 1 lpm

24%

NC 2 lpm

27%

NC 3 lpm

30%

NC 4 lpm

33%

NC 5 lpm

35%

NC 6 lpm

38%

the max a NC can be set to is

6 lpm

AC/PRVC- RR

you should use pt hx as well as any lab data available to guide decision

normal RR in adults

12-24 bpm

for a higher pCO2 values on ABG→ AC/PRVC RR

choose a higher initial RR to aid ventilation and correct respiratory acidosis

average total lung capacity of an adult

about 6 L

the tidal volume (Vt) is

the volume of air that is inhaled or exhaled in a single breath

tidal volume

Vt

factors that affect lung volumes→ larger volumes

taller height

higher altitudes

non-obese

factors that affect lung volumes→ smaller volumes

shorter height

lower altitudes

obese

selecting appropriate Vt→ AC/PRVC

volumes > 10 ml/kg can cause severe and accelerated complications such as volutrama, barotrauma, biotrauma; leading to ARDS

standard Vt selection

6-8 mL/kg

Vt selection

calculate predicted body weight (PBW)

Vt selection→ males

males= 50 +2.3 (height (in) - 60)

Vt selection→ females

females= 45.5 +2.3 (height(in) -60)

ARDSnet

strategy using high RR and low Vt (ARDS)

goals of ARDSnet

• Vt at 6 mL/kg PBW

• PaO2 55-80mmHg or SpO2 88-95%

• Plateau pressure </= 30 cm H2O

• pH 7.15-7.45

PEEP→ AC/PRVC

a small amount of end-expiratory pressure, my convention 5cm H2O, is used to mitigate alveolar collapse

complications of PEEP

decreased venous return, barotrauma, increased ICP

higher levels of PEEP

can be used to improve hypoxemia or reduce ventilator associated lung injury as in ARDS

FiO2 in AC/PRVC is initially set at

100%

goal of FiO2

titrate down to a goal of <60% as tolerated to avoid complication of O2 toxicity

FiO2 is ideal at . . .

generally at <50% and ideally at 40% before initiating SBT