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49 terms

Test 4 mech. vent. -Ch13

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When would you want to change Vt and rate?
to correct resp. alkalosis or acidosis
To correct resp. acidosis you could do what to the Va?
increase it
Causes of acute resp. acidosis
pulm. edema, pneumonia, aw disease, pleural effusions, chest wall abnormalities, neuromuscular disorders
There are two ways you could correct resp. acidosis in VV?
increase the vt to 12 ml/kg of ideal body weight, or if vt is already set at 12 ml/kg of ideal body weight, you could chg the f to correct high Co2
How could you correct resp. acidosis in PV?
increase or decrease the pressure to achieve Vt of 12 ml/kg IBW. then measure the exVt
Causes of Respiratory Alkalosis
hypoxia with compensated hyperventilation, meds, mech. vent., CNS disorders, anxiety, metabolic problems
To correct Resp. Alkalosis in VV, you could?
decrease the f to decrease the Vt
How could you correct resp. alkalosis in PV?
decrease f then set pressure. When you get to a Vt of 12 ml/kg IBW, leave pressure setting there. bc in PV pressure and volume are directly measured
metabolic acidosis
pts at risk for developing resp. muscle fatigue
causes of metabolic acidosis
ketoacidosis, uremic acidosis, diarrhea, renal loss, lactic acidosis, toxins
causes of metabolic alkalosis
vomiting, diuretic, potassium deficiency, bicarb administration
If pure respiratory acidosis persists even after Va has been increased, the pt may have a problem with
increased deadspace
causes of increased deadspace
pulmonary embolism, decreased CO-resulting in low pulmonary perfusion
increased deadspace can also occur when vent support reduces pulmonary blood flow to the lungs by causing
high alveolar pressure, such as application of high peep
Normal Vd/Vt
O.2 to 0.4
EQ for Vd/Vt
Paco2-Peco2/ Paco2
Historically, iatrogenic hyperventilation was used in pts with
acute head injury and increased ICP
Normal ICP
0-5
hyperventilaiton reduces Co2 in the blood which is assc. with constriction of cerebral blood vessels and a
decrease in blood flow to the brain
For head injury's with increased ICP
do not recommend prophylactic hyperventilation (Paco2 <25 mmhg) during the 1st 24 hrs
Iatrogenic hyperventilation is only used for _________ when ICP is elevated
brief periods
Pt has a increased ICP, hyperventilated them will
decrease CO2, blood flow to brain
Mild hyperventilation (Paco2 30-35 mmhg) may be used for
longer periods in situations in which increased ICP is refractory to standard txs of sedation, analgesia, neuromuscular block, cerebralspinal fluid drainage
Paco2 should at least be maintained at normal levls for
1st 24 hrs
Occasionally it becomes impossible to maintain normal vent. without risking
lung damage from high pressure and volumes
Pts with ARDS or Status asthmaticus and sometimes COPD, who require vent support are at risk for
vent-induced injury
With permissive hypercapnia you want to
sedate pt (b/c increased Co2 stimulates the drive to breath), let Co2 rise (>50 to 150 mm hg), PH fall ( >7.10 to 7.30), gradually rise not abruptly
Co2 >200 mmhg can result in
Co2 narcosis
Efforts to keep Paco2 near a pts normal might include
removing sources of mech. deadspace, increasing the f
When the decision is made to allow Paco2 to increase, the following may be used
Allow Co2 to increase and Ph to decrease with out changing rate or vol, avoid high vent pressure and maintain O2, administer sodium bicarb-THAM-or carbicarb to keep Ph > 7.25
to decrease Co2 production you can
use a paralytic, cooling pt, restrict glucose intake
Co2 is a powerful
vasodilator of cerebral vessels
increased Co2 levels can result in
cerebral edema and increase ICp
PHY (permissive hyperventilation) is contraindicated in
head traum, intra cranial disease
PHY (permissive hyperventilation) is also contraindicated in
pts with closed head injury and ARDS; so you would want to change to PV, increase rate slightly to maintain PH, then let the Co2 rise
Circulatory effects with PHY
decreased MI contractility, arrythmias, vasodilation- which results in increased CO, pulmonary hypertension
During mech. vent several techniques can be used to help
clear secretions from the AW
You clear secretions from an artifical aw by
suctioning
Suctioning is performed
PRN, based on assessment of the pt (BS) and visibility examing the artificial aw ( if you can see it)
Acute CHF pts
often have pink frothy secretions that do not block the aw, so suctioning is not necessary. secretions will continue until the cause has been treated.
suctioning CHF pts with pulmonary edema will only worsen the
hypoxemia, which is commonly seen in these pts
Suctioning should be preceded and followed by
hyperoxygenation with 100% O2 for 30sec (before), then 1 min after
hyperoxygenating and hyperventilating pts before/after suctioning can be done by
resusctitation bag
Sx must not exceed how long
15 sec
What are the suctioning pressure for adults
-100 to -120 mmhg
what are the suctioning pressure for a child
-80 to -100 mmhg
what are the suctioning pressure for an infant
-60 to -100 mmhg
Complications with suctioning
can cause pt= discomfort, anxiety, coughing, bronchospasm, hemmorrhage, AW edema, ulceration of the mucosal wall (atelectasis), arrythmias, tachycardia, bradycardia
What is the #1 most common hazard of suctioning?
hypoxemia