Thomas Anderson
@respiratorytom.bsky.social
Respiratory Therapist | #MechanicalVentilation | #Resuscitation | #Airway | #Education | #emimcc
2+3: Yes, the concern is that the respiratory alkalosis exposes the patient to risk of decreased cerebral blood flow, which at its worst would be a stroke. I believe there’s some literature to suggest an increased risk of stroke in DKA pts.
March 11, 2025 at 5:06 PM
2+3: Yes, the concern is that the respiratory alkalosis exposes the patient to risk of decreased cerebral blood flow, which at its worst would be a stroke. I believe there’s some literature to suggest an increased risk of stroke in DKA pts.
Great questions!
1. No, I don’t particularly care what the pCO2 is. I care about the amount of mechanical power I’m introducing into the system. I think that a mild resp acidosis is preferable to a mild resp alkalosis, because the acidosis comes with less mechanical power.
1. No, I don’t particularly care what the pCO2 is. I care about the amount of mechanical power I’m introducing into the system. I think that a mild resp acidosis is preferable to a mild resp alkalosis, because the acidosis comes with less mechanical power.
March 11, 2025 at 5:06 PM
Great questions!
1. No, I don’t particularly care what the pCO2 is. I care about the amount of mechanical power I’m introducing into the system. I think that a mild resp acidosis is preferable to a mild resp alkalosis, because the acidosis comes with less mechanical power.
1. No, I don’t particularly care what the pCO2 is. I care about the amount of mechanical power I’m introducing into the system. I think that a mild resp acidosis is preferable to a mild resp alkalosis, because the acidosis comes with less mechanical power.
by degree. My understanding is mild/moderate acidoses are well tolerated, and maybe not worth the above risks. A severe acidosis wherein the patient is otherwise moribund is an easier sell. Harm associated with P-SILI in this setting also makes the addition of NIV a little more attractive.
March 11, 2025 at 2:07 PM
by degree. My understanding is mild/moderate acidoses are well tolerated, and maybe not worth the above risks. A severe acidosis wherein the patient is otherwise moribund is an easier sell. Harm associated with P-SILI in this setting also makes the addition of NIV a little more attractive.
So there’s risk of VILI, risk inherent to the equipment, and risk associated with the intention of the treatment. The likelihood of any of these risks becoming harm is variable, and most of them have some degree of mitigation.
On the other side of the ledger, the risk of the acidosis increases
On the other side of the ledger, the risk of the acidosis increases
March 11, 2025 at 2:07 PM
So there’s risk of VILI, risk inherent to the equipment, and risk associated with the intention of the treatment. The likelihood of any of these risks becoming harm is variable, and most of them have some degree of mitigation.
On the other side of the ledger, the risk of the acidosis increases
On the other side of the ledger, the risk of the acidosis increases
which exacerbates all the usual cardiovascular insults.
My understanding is even though CO2 is the main driver of CSF pH, they also have separate effects on cerebral circulation: a compensated, severe resp alkalosis still causes cerebral vasoconstriction which presumably carries some risk of CVA.
My understanding is even though CO2 is the main driver of CSF pH, they also have separate effects on cerebral circulation: a compensated, severe resp alkalosis still causes cerebral vasoconstriction which presumably carries some risk of CVA.
March 11, 2025 at 2:07 PM
which exacerbates all the usual cardiovascular insults.
My understanding is even though CO2 is the main driver of CSF pH, they also have separate effects on cerebral circulation: a compensated, severe resp alkalosis still causes cerebral vasoconstriction which presumably carries some risk of CVA.
My understanding is even though CO2 is the main driver of CSF pH, they also have separate effects on cerebral circulation: a compensated, severe resp alkalosis still causes cerebral vasoconstriction which presumably carries some risk of CVA.
In terms of IMV, the risk profile is a little more clear. For patients with ALI, there is a strong association between driving pressure or resp rate and mortality. To alkalotize the patient is to court that association. Increasing either of these variables also increases intrathoracic pressure
March 11, 2025 at 2:07 PM
In terms of IMV, the risk profile is a little more clear. For patients with ALI, there is a strong association between driving pressure or resp rate and mortality. To alkalotize the patient is to court that association. Increasing either of these variables also increases intrathoracic pressure
Causing an aspiration pneumonitis with NIV is just about the worst outcome of the therapy besides death. Adding the machine itself also creates potential risk: it aerosolizes the pathogen and dislodged tubing turns the mask into a pillow when there’s no fresh gas source.
March 11, 2025 at 2:07 PM
Causing an aspiration pneumonitis with NIV is just about the worst outcome of the therapy besides death. Adding the machine itself also creates potential risk: it aerosolizes the pathogen and dislodged tubing turns the mask into a pillow when there’s no fresh gas source.
To generate an alkalosis on NIPPV, we’re mostly talking about augmenting Vt, as overriding a spontaneously breathing patient’s intrinsic rate is likely to just create asynchrony. Adding driving pressure to the system carries risk: cardiac effects, lung stress, insufflation of the esophagus.
March 11, 2025 at 2:07 PM
To generate an alkalosis on NIPPV, we’re mostly talking about augmenting Vt, as overriding a spontaneously breathing patient’s intrinsic rate is likely to just create asynchrony. Adding driving pressure to the system carries risk: cardiac effects, lung stress, insufflation of the esophagus.
I do, in fact, think it’s bonkers to use positive pressure to create a respiratory alkalosis to compensate for a metabolic acidosis. I perceive a pretty meaningful difference between positive pressure breathing and negative pressure breathing.
March 11, 2025 at 3:14 AM
I do, in fact, think it’s bonkers to use positive pressure to create a respiratory alkalosis to compensate for a metabolic acidosis. I perceive a pretty meaningful difference between positive pressure breathing and negative pressure breathing.
I’ve seen a couple patients develop malignant hyperthermia after sux. It’s a real bummer to manage in NICU where we don’t have immediate access to dantrolene in the middle of the night.
March 3, 2025 at 5:42 PM
I’ve seen a couple patients develop malignant hyperthermia after sux. It’s a real bummer to manage in NICU where we don’t have immediate access to dantrolene in the middle of the night.
Permissive hypercapnea FTW.
January 20, 2025 at 3:01 PM
Permissive hypercapnea FTW.
In any case, I’ll end it here. Thanks for reading, and please read through the quoted thread, it is a very good introduction to NIPPV for clinicians who maybe have to interact with it very occasionally.
December 15, 2024 at 8:21 PM
In any case, I’ll end it here. Thanks for reading, and please read through the quoted thread, it is a very good introduction to NIPPV for clinicians who maybe have to interact with it very occasionally.
I think there’s also a great deal of individualization you can do with rise time and Ti (which is usually a Ti max: the longest inspiration can last, but the patient is free to cycle before it reaches that time).
December 15, 2024 at 8:21 PM
I think there’s also a great deal of individualization you can do with rise time and Ti (which is usually a Ti max: the longest inspiration can last, but the patient is free to cycle before it reaches that time).
trapped behind bronchoconstriction or collapse to be exhaled. This is free ventilation because it doesn’t cost any additional driving pressure, but removes CO2.
December 15, 2024 at 8:21 PM
trapped behind bronchoconstriction or collapse to be exhaled. This is free ventilation because it doesn’t cost any additional driving pressure, but removes CO2.
exchange, but are being distorted by nearby hyperinflated & collapsed units. I think by finding a “best EPAP” we reduce both shunt and deadspace by giving the COPD lung some structure it has otherwise lost. EPAP that exceeds a critical opening pressure allows CO2 that is…
December 15, 2024 at 8:21 PM
exchange, but are being distorted by nearby hyperinflated & collapsed units. I think by finding a “best EPAP” we reduce both shunt and deadspace by giving the COPD lung some structure it has otherwise lost. EPAP that exceeds a critical opening pressure allows CO2 that is…
less pressure per unit of volume. We also, presumably, delivery lung-protective ventilation. In my practice, EPAP becomes intolerable around 10 cmH2O.
In the context of AECOPD, I think individualizing EPAP can stabilize lung units that can otherwise participate in gas…
In the context of AECOPD, I think individualizing EPAP can stabilize lung units that can otherwise participate in gas…
December 15, 2024 at 8:21 PM
less pressure per unit of volume. We also, presumably, delivery lung-protective ventilation. In my practice, EPAP becomes intolerable around 10 cmH2O.
In the context of AECOPD, I think individualizing EPAP can stabilize lung units that can otherwise participate in gas…
In the context of AECOPD, I think individualizing EPAP can stabilize lung units that can otherwise participate in gas…
same tidal volume and is thus presumably lung protective. Applying the same logic to NIPPV, I believe we should use the highest EPAP that is tolerable and doesn’t reduce Vt for the same IPAP (overdistention). In doing so, we maximize compliance and thus offload WOB by making each breath cost…
December 15, 2024 at 8:21 PM
same tidal volume and is thus presumably lung protective. Applying the same logic to NIPPV, I believe we should use the highest EPAP that is tolerable and doesn’t reduce Vt for the same IPAP (overdistention). In doing so, we maximize compliance and thus offload WOB by making each breath cost…
and collapsing of lung units, a low EPAP and high IPAP could lead to exactly that. Additionally, it currently seems as though driving pressure is the variable that predominantly drives VILI. We know that improving lung compliance reduces driving pressure for the…
December 15, 2024 at 8:21 PM
and collapsing of lung units, a low EPAP and high IPAP could lead to exactly that. Additionally, it currently seems as though driving pressure is the variable that predominantly drives VILI. We know that improving lung compliance reduces driving pressure for the…
3. I think there’s value in setting EPAP with significantly more consideration than it typically receives. I don’t think the fact that we’re using a mask instead of an ETT absolves us of considering the causes of VILI. If we consider atelectrauma to be the repeated opening…
December 15, 2024 at 8:21 PM
3. I think there’s value in setting EPAP with significantly more consideration than it typically receives. I don’t think the fact that we’re using a mask instead of an ETT absolves us of considering the causes of VILI. If we consider atelectrauma to be the repeated opening…
making breathing harder. And presumably we’re using NIPPV because breathing is already hard and for the explicit purpose of making it less hard. Measurements of opening pressure vary, and different sources cite pressures as low as 15 cmH2O and as high as 45 cmH2O. I just try to limit total pressure.
December 15, 2024 at 8:21 PM
making breathing harder. And presumably we’re using NIPPV because breathing is already hard and for the explicit purpose of making it less hard. Measurements of opening pressure vary, and different sources cite pressures as low as 15 cmH2O and as high as 45 cmH2O. I just try to limit total pressure.