3.2: Choosing Initial Settings for a Control Mode

Last updated
Save as PDF

Page ID: 101814

Yvonne Drasovean
Fanshawe College

$ \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } $

$ \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} $

$ \newcommand{\dsum}{\displaystyle\sum\limits} $

$ \newcommand{\dint}{\displaystyle\int\limits} $

$ \newcommand{\dlim}{\displaystyle\lim\limits} $

$ \newcommand{\id}{\mathrm{id}}$ $ \newcommand{\Span}{\mathrm{span}}$

( \newcommand{\kernel}{\mathrm{null}\,}\) $ \newcommand{\range}{\mathrm{range}\,}$

$ \newcommand{\RealPart}{\mathrm{Re}}$ $ \newcommand{\ImaginaryPart}{\mathrm{Im}}$

$ \newcommand{\Argument}{\mathrm{Arg}}$ $ \newcommand{\norm}[1]{\| #1 \|}$

$ \newcommand{\inner}[2]{\langle #1, #2 \rangle}$

$ \newcommand{\Span}{\mathrm{span}}$

$ \newcommand{\id}{\mathrm{id}}$

$ \newcommand{\Span}{\mathrm{span}}$

$ \newcommand{\kernel}{\mathrm{null}\,}$

$ \newcommand{\range}{\mathrm{range}\,}$

$ \newcommand{\RealPart}{\mathrm{Re}}$

$ \newcommand{\ImaginaryPart}{\mathrm{Im}}$

$ \newcommand{\Argument}{\mathrm{Arg}}$

$ \newcommand{\norm}[1]{\| #1 \|}$

$ \newcommand{\inner}[2]{\langle #1, #2 \rangle}$

$ \newcommand{\Span}{\mathrm{span}}$ $ \newcommand{\AA}{\unicode[.8,0]{x212B}}$

$ \newcommand{\vectorA}[1]{\vec{#1}} % arrow$

$ \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow$

$ \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } $

$ \newcommand{\vectorC}[1]{\textbf{#1}} $

$ \newcommand{\vectorD}[1]{\overrightarrow{#1}} $

$ \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} $

$ \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} $

$ \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } $

$\newcommand{\longvect}{\overrightarrow}$

$ \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} $

$\newcommand{\ket}[1]{\left| #1 \right>}$
$\newcommand{\bra}[1]{\left< #1 \right|}$
$\newcommand{\braket}[2]{\left< #1 \vphantom{#2} \right| \left. #2 \vphantom{#1} \right>}$
$\newcommand{\braopket}[3]{\left< #1 \vphantom{#2}\vphantom{#3} \right| #2 \vphantom{#1}\vphantom{#3} \left| #3 \vphantom{#1}\vphantom{#2} \right>}$
$\newcommand{\qmvec}[1]{\mathbf{\vec{#1}}}$
$\newcommand{\op}[1]{\hat{\mathbf{#1}}}$
$\newcommand{\expect}[1]{\langle #1 \rangle}$
$\newcommand{\dfn}[1]{\emph{\textbf{#1}}}$

$\newcommand{\avec}{\mathbf a}$ $\newcommand{\bvec}{\mathbf b}$ $\newcommand{\cvec}{\mathbf c}$ $\newcommand{\dvec}{\mathbf d}$ $\newcommand{\dtil}{\widetilde{\mathbf d}}$ $\newcommand{\evec}{\mathbf e}$ $\newcommand{\fvec}{\mathbf f}$ $\newcommand{\nvec}{\mathbf n}$ $\newcommand{\pvec}{\mathbf p}$ $\newcommand{\qvec}{\mathbf q}$ $\newcommand{\svec}{\mathbf s}$ $\newcommand{\tvec}{\mathbf t}$ $\newcommand{\uvec}{\mathbf u}$ $\newcommand{\vvec}{\mathbf v}$ $\newcommand{\wvec}{\mathbf w}$ $\newcommand{\xvec}{\mathbf x}$ $\newcommand{\yvec}{\mathbf y}$ $\newcommand{\zvec}{\mathbf z}$ $\newcommand{\rvec}{\mathbf r}$ $\newcommand{\mvec}{\mathbf m}$ $\newcommand{\zerovec}{\mathbf 0}$ $\newcommand{\onevec}{\mathbf 1}$ $\newcommand{\real}{\mathbb R}$ $\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}$ $\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}$ $\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}$ $\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}$ $\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}$ $\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}$ $\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}$ $\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}$ $\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}$ $\newcommand{\laspan}[1]{\text{Span}\{#1\}}$ $\newcommand{\bcal}{\cal B}$ $\newcommand{\ccal}{\cal C}$ $\newcommand{\scal}{\cal S}$ $\newcommand{\wcal}{\cal W}$ $\newcommand{\ecal}{\cal E}$ $\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}$ $\newcommand{\gray}[1]{\color{gray}{#1}}$ $\newcommand{\lgray}[1]{\color{lightgray}{#1}}$ $\newcommand{\rank}{\operatorname{rank}}$ $\newcommand{\row}{\text{Row}}$ $\newcommand{\col}{\text{Col}}$ $\renewcommand{\row}{\text{Row}}$ $\newcommand{\nul}{\text{Nul}}$ $\newcommand{\var}{\text{Var}}$ $\newcommand{\corr}{\text{corr}}$ $\newcommand{\len}[1]{\left|#1\right|}$ $\newcommand{\bbar}{\overline{\bvec}}$ $\newcommand{\bhat}{\widehat{\bvec}}$ $\newcommand{\bperp}{\bvec^\perp}$ $\newcommand{\xhat}{\widehat{\xvec}}$ $\newcommand{\vhat}{\widehat{\vvec}}$ $\newcommand{\uhat}{\widehat{\uvec}}$ $\newcommand{\what}{\widehat{\wvec}}$ $\newcommand{\Sighat}{\widehat{\Sigma}}$ $\newcommand{\lt}{<}$ $\newcommand{\gt}{>}$ $\newcommand{\amp}{&}$ $\definecolor{fillinmathshade}{gray}{0.9}$

When setting the ventilator, a “one-size-fits-all” mentality should not be used. We have talked a lot about mechanical ventilation as a trauma. Every patient is different and must be approached based on their individual needs and the pathophysiology that they are dealing with. A clinician must consider their patient and the reason for intubation when they are setting up their initial settings. Let’s walk through a systematic approach to choosing your control mode settings based on your patient and their presenting illness.

PEEP and FiO₂

We have discussed in depth the importance of maintaining an SPO₂ of more than $A simple black outline of a tree with a thick trunk and broad, leafy canopy.$ but less than $A simple design featuring an abstract human figure in a yoga pose with outstretched arms.$ , so we do not over-oxygenate and cause the release of oxygen free radicals (see Chapter 2). We have also discussed the relationship between PEEP and FiO₂ and how they both contribute to oxygenation (see Chapter 2). FiO₂ can be increased or decreased to deliver a higher concentration into the lungs with every breath. The higher the oxygen level being delivered, the more oxygen will be present to diffuse across the alveolar-capillary membrane into the blood. PEEP contributes by recruiting (opening) collapsed alveoli—allowing more lung surface to exchange oxygen with every breath and increasing the oxygen getting into the blood with every breath, as well as increasing the driving pressure to push the oxygen across the alveolar-capillary membrane. Both FiO₂ and PEEP can directly increase the amount of oxygen that gets into the blood to circulate to the vital organs. If any of this is unclear, review Chapter 2, and then come back and read this section again.

So how do you approach setting FiO₂ and PEEP? The easiest way to approach FiO₂ is to start at $Icon of a hand with an extended index finger, indicating the gesture for "number one" or "pointing."$ or $A simple black silhouette of a butterfly.$ . If the patient was requiring high oxygen before intubation, start at $A simple black outline of a light bulb representing an idea or inspiration.$ . If the patient was not requiring a lot or any oxygen prior to intubation, then start at $A simple black silhouette of a microphone on a white background.$ . But you don’t stop here! Within minutes of starting ventilation, titrate (increase or decrease) the FiO₂ by $A simple black silhouette of a DNA double helix.$ based on the SpO₂ as you learned in Chapter 2. Within 5 minutes, you should be able to settle on an FiO₂ that correlates to an $A simple black silhouette of a fish facing to the right.$ (and $A minimalist design of a light bulb with lines representing rays of light emanating from it.$ ). Leave the FiO₂ at this level until you get arterial blood gas (ABG) results and can make further changes from there.

Key Takeaway

FiO₂ is the only setting that you will change frequently when you first set up the ventilator. It is common that a clinician could start at $A simple black outline of a light bulb representing an idea or inspiration.$ and over the span of 5 min, wean the FiO₂ to $An outline of a friendly, cartoon-style dog, standing and facing forward.$ to target their SpO₂. For all other settings, in most cases, you will set them and then wait until you asses arterial blood gases (ABGs) after waiting a minimum of 30 minutes.

Initial PEEP settings should be anywhere from $Abstract spiral design in black on a white background, resembling a modern artistic pattern.$ . Remember, the minimum PEEP is $A simple black silhouette of a tree with a round canopy and a thick trunk.$ . It is always better to start low and go up after you take an ABG and the patient has had some time on the ventilator. People with healthy lungs should be started at a PEEP of $A simple black silhouette of a rabbit facing to the right.$ . Higher PEEP should be considered for, on an individual basis, as initial settings when you have patients with known atelectasis, pulmonary edema or evidence of thickening of the alveolar-capillary membrane in their diagnosis.

Remember, increasing PEEP is not without its dangers. If PEEP is increased too much, it can decrease blood return to the heart and also decrease lung compliance. Ensure the patient’s pathophysiology would benefit from PEEP prior to initiating at 8 or 10. You can always increase the PEEP after you take a blood gas. It is better to allow the patient to settle on the ventilator with lower PEEPs and gradually increase later, if you are not sure whether they would benefit from higher PEEPs.

Refer to this summary table for FiO₂ and PEEP initial settings:

Table 3.2.1: FiO₂ and PEEP Initial Settings
Setting	Patient Status	Initial Settings
FiO₂	Hypoxic prior to intubation	$A simple black outline of a cactus in a pot.$
FiO₂	No/little need for supplemental oxygen	$Icon of a hand with an extended index finger, indicating the gesture for "number one" or "pointing."$
PEEP	Most patients	$A simple black silhouette of a rabbit facing to the right.$
PEEP	Known atelectasis or thickening of their alveolar-capillary membrane	$A simple black silhouette of a cat sitting with its tail curved.$

Respiratory Rate

One of the cornerstones of both control modes—both volume and pressure—is that the clinician sets the minimum respiratory rate the patient must breathe every minute. Remember, the patient can trigger additional breaths above that set rate, but all breaths will be delivered the exact same based on what the clinician sets in the other settings.

When choosing a respiratory rate for adult patients, you always want to be within the normal physiologic respiratory rates. An adult person breathing normally at rest usually breathes $A simple black silhouette of a person walking.$ when there are no issues with their lungs. When setting the respiratory rate on the ventilator, initial respiratory rates should be chosen within that range.

So how do you choose what number to actually set? The best way to do this is to look at how your patient was breathing prior to intubation and think about what physiologic process was going on. Do they have an issue with their lungs? Why did we intubate them?

If the patient was breathing normally and was only intubated for airway protection, but their respiratory rate was in the lower end of normal, this patient can safely be initiated with a lower $A simple black silhouette of a tree with a broad canopy and visible trunk.$ (still within those normal limits).

If the patient has compromised lungs or was breathing rapidly prior to intubation and is being intubated due to oxygenation or ventilation failure, we know the chemoreceptors in the brain were stimulating them to breathe rapidly, most likely because of elevated CO₂ levels or low oxygen. They will be tachypneic, breathing at a higher $A simple black silhouette of a tree with a broad canopy and visible trunk.$ than normal ( $Black silhouette of a person holding a trophy, representing achievement or victory.$ usually). The patient may also be showing signs of increased work of breathing with accessory muscle use. When you note signs of tachypnea in a patient prior to intubation, they are most likely requiring the higher $A simple black silhouette of a tree with a broad canopy and visible trunk.$ to fix an abnormality in their CO₂ or O₂ levels. Even without an ABG to confirm this diagnosis, initial settings can still be set based on this observation. We, as clinicians, need to mimic a patient’s physiologic breathing.

Now, the aim of mimicking physiologic breathing does not mean that you should always copy a patient’s $A simple black silhouette of a tree with a broad canopy and visible trunk.$ . Some of these patients are breathing faster than $A simple black outline of a house with a triangular roof, featuring a chimney and a rectangular door.$ . With positive pressure ventilation, that is difficult to do without causing extra damage to the lungs because, remember, we are pushing the air into the lungs, and the patient is not spontaneously pulling the air in which is less traumatic to their alveoli (see Chapter 1). Therefore, do not copy a too-high rate of breathing, which would cause trauma. Instead, choose a $A simple black silhouette of a tree with a broad canopy and visible trunk.$ on the high side of normal. So, if normal is $A simple black silhouette of a light bulb, symbolizing ideas or creativity.$ , a clinician should start at $A simple, black silhouette of a pine tree with a triangular shape and a flat base.$ for this patient’s $A simple black silhouette of a tree with a broad canopy and visible trunk.$ .

With positive pressure ventilation, an $A simple black silhouette of a tree with a broad canopy and visible trunk.$ of higher than $A simple black silhouette of a cat sitting, facing to the right.$ can start causing patient asynchrony and potentially contribute to gas trapping and damage to the lungs. It takes a trained eye to look at ventilator waveforms and patient respiratory efforts to ensure this outcome is not happening. Clinicians who are not as experienced with ventilation should try to stay below $A simple black silhouette of a cat sitting, facing to the right.$ . A physician and/or RRT should be consulted to ensure a higher $A simple black silhouette of a tree with a broad canopy and visible trunk.$ is appropriate.

Remember, these are your initial settings only. You would start with this $A simple black silhouette of a tree with a broad canopy and visible trunk.$ and then do an ABG to assess how well the CO₂ and O₂ levels are after 30-60 minutes on the ventilator and make changes accordingly (we will discuss this further in Chapters 8 and 9).

Table 3.2.2: Initial Settings – $A simple black silhouette of a tree with a broad canopy and visible trunk.$
Setting	Patient Status	Initial Settings
$A simple black silhouette of a tree with a broad canopy and visible trunk.$	Normal lungs/intubated for airway protection only or slow $A simple black silhouette of a tree with a broad canopy and visible trunk.$ prior to intubation.	$A simple, black outline of a megaphone, symbolizing communication or announcement.$
	Compromised lungs/intubated due to oxygenation or ventilation issues or tachypnea prior to intubation.	$A simple, black silhouette of a pine tree with a triangular shape and a flat base.$

Key Takeaway

For both Pressure and Volume control modes, the clinician needs to set FiO₂, PEEP and $A simple black silhouette of a tree with a broad canopy and visible trunk.$ . Additional settings will differ based on whether you have chosen Volume or Pressure Control.

“Choosing Initial Settings for a Control Mode” from Basic Principles of Mechanical Ventilation by Melody Bishop, © Sault College is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Search

Text Color

Text Size

Margin Size

Font Type

Key Takeaway

Key Takeaway

PEEP and FiO2

Respiratory Rate

PEEP and FiO₂