How do you Ventilate your patients in the Operating room?

[BLADEMDA]

Here is how I do it:

Typical ASA 3 patient (which is my usual) gets 7 ml/kg (predicted body weight) with a Peep of 6. I don't always stress a recruitment maneuver to the midlevels but I encourage at least one.

I figure some of you are sticking with the old strategy of 10-12 ml/kg with zero peep while others are utilizing 6 mg/kg with Peep of 8-10 plus regular interval recruitment maneuvers.

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[BLADEMDA]

Lancet. 2014 Aug 9;384(9942):495-503. doi: 10.1016/S0140-6736(14)60416-5. Epub 2014 Jun 2.
High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial): a multicentre randomised controlled trial.
PROVE Network Investigators for the Clinical Trial Network of the European Society of Anaesthesiology, Hemmes SN, Gama de Abreu M, Pelosi P, Schultz MJ.
Collaborators (104)

Abstract
BACKGROUND:
The role of positive end-expiratory pressure in mechanical ventilation during general anaesthesia for surgery remains uncertain. Levels of pressure higher than 0 cm H2O might protect against postoperative pulmonary complications but could also cause intraoperative circulatory depression and lung injury from overdistension. We tested the hypothesis that a high level of positive end-expiratory pressure with recruitment manoeuvres protects against postoperative pulmonary complications in patients at risk of complications who are receiving mechanical ventilation with low tidal volumes during general anaesthesia for open abdominal surgery.

METHODS:
In this randomised controlled trial at 30 centres in Europe and North and South America, we recruited 900 patients at risk for postoperative pulmonary complications who were planned for open abdominal surgery under general anaesthesia and ventilation at tidal volumes of 8 mL/kg. We randomly allocated patients to either a high level of positive end-expiratory pressure (12 cm H2O) with recruitment manoeuvres (higher PEEP group) or a low level of pressure (≤2 cm H2O) without recruitment manoeuvres (lower PEEP group). We used a centralised computer-generated randomisation system. Patients and outcome assessors were masked to the intervention. Primary endpoint was a composite of postoperative pulmonary complications by postoperative day 5. Analysis was by intention-to-treat. The study is registered at Controlled-Trials.com, number ISRCTN70332574.

FINDINGS:
From February, 2011, to January, 2013, 447 patients were randomly allocated to the higher PEEP group and 453 to the lower PEEP group. Six patients were excluded from the analysis, four because they withdrew consent and two for violation of inclusion criteria. Median levels of positive end-expiratory pressure were 12 cm H2O (IQR 12-12) in the higher PEEP group and 2 cm H2O (0-2) in the lower PEEP group. Postoperative pulmonary complications were reported in 174 (40%) of 445 patients in the higher PEEP group versus 172 (39%) of 449 patients in the lower PEEP group (relative risk 1·01; 95% CI 0·86-1·20; p=0·86). Compared with patients in the lower PEEP group, those in the higher PEEP group developed intraoperative hypotension and needed more vasoactive drugs.

INTERPRETATION:
A strategy with a high level of positive end-expiratory pressure and recruitment manoeuvres during open abdominal surgery does not protect against postoperative pulmonary complications. An intraoperative protective ventilation strategy should include a low tidal volume and low positive end-expiratory pressure, without recruitment manoeuvres.

 

[BLADEMDA]

Role of Recruitment Maneuvers for Lung-protective Ventilation in the Operating Room Remains Unclear
Tanja A. Treschan, M.D.; Martin Beiderlinden, P.D., M.D.

The Journal of the American Society of Anesthesiologists 2 2015, Vol.122, 472-473. doi:10.1097/ALN.000000000000054

1 about lung-protective ventilation in the operating room. We congratulate the authors for their word of caution and farsightedness. We fully agree that low tidal volumes (VT) are an essential part of lung-protective ventilation in patients with acute respiratory syndrome, but we would like to point out that even VT of 6 ml/kg ideal body weight have been shown to be too high in severe cases.2 This emphasizes that the concept of protective ventilation is far more complex than often suggested when referred to protective ventilation as using low VT.
3 However, only very few trials, including our own study,4 restricted their intervention to this factor. Goldenberg et al. acknowledged our work but incorrectly stated that “no recruitment maneuvers” were performed. All patients received a lung expansion maneuver consisting of three manual bag ventilations with a maximum pressure of 40 cm H2O shortly before extubation.4 Despite this effort, significantly more patients ventilated with low VT had atelectasis directly after surgery. Thus, a single recruitment maneuver with manual bag inflations before extubation is not sufficient to counterbalance the effects of low VTwhen a low positive-end expiratory pressure (PEEP) of 5 cm H2O is used. Therefore, we call into question the conclusion by Goldenberg et al. that “during anesthesia, protective ventilation is beneficial when both lower VT and a recruitment strategy are included, but not when lower VT used alone.” We would rather stress that neither the optimal combination of PEEP and VT nor the best recruitment strategy is known yet.5 In this study, 900 patients undergoing upper abdominal surgery were ventilated with 8 ml/kg ideal body weight and randomly assigned to PEEP of 12 cm H2O plus multiple recruitment maneuvers or PEEP of 2 cm H2O or less without recruitment maneuvers. There was no difference in postoperative pulmonary complications between the two groups, but in patients ventilated with high PEEP, intraoperative hypotension was a major problem. As a consequence, neither high PEEP nor regular recruitment maneuvers per se are lung protective with regard to postoperative pulmonary complications but cause clinically important adverse effects.6 or inspiratory oxygen concentration,7 we believe that their conclusion cannot be overemphasized.
Competing Interests

The authors declare no competing interests.
Tanja A. Treschan, M.D., Martin Beiderlinden, P.D.,
M.D. Duesseldorf University Hospital, Heinrich-Heine University
Duesseldorf, Duesseldorf, Germany (T.A.T.).
tanja.treschan@med.

 

[BLADEMDA]

N Engl J Med. 2013 Aug 1;369(5):428-37. doi: 10.1056/NEJMoa1301082.
A trial of intraoperative low-tidal-volume ventilation in abdominal surgery.
Futier E1, Constantin JM, Paugam-Burtz C, Pascal J, Eurin M, Neuschwander A, Marret E, Beaussier M, Gutton C, Lefrant JY,Allaouchiche B, Verzilli D, Leone M, De Jong A, Bazin JE, Pereira B, Jaber S; IMPROVE Study Group.
Collaborators (50)

Author information

Abstract
BACKGROUND:
Lung-protective ventilation with the use of low tidal volumes and positive end-expiratory pressure is considered best practice in the care of many critically ill patients. However, its role in anesthetized patients undergoing major surgery is not known.

METHODS:
In this multicenter, double-blind, parallel-group trial, we randomly assigned 400 adults at intermediate to high risk of pulmonary complications after major abdominal surgery to either nonprotective mechanical ventilation or a strategy of lung-protective ventilation. The primary outcome was a composite of major pulmonary and extrapulmonary complications occurring within the first 7 days after surgery.

RESULTS:
The two intervention groups had similar characteristics at baseline. In the intention-to-treat analysis, the primary outcome occurred in 21 of 200 patients (10.5%) assigned to lung-protective ventilation, as compared with 55 of 200 (27.5%) assigned to nonprotective ventilation (relative risk, 0.40; 95% confidence interval [CI], 0.24 to 0.68; P=0.001). Over the 7-day postoperative period, 10 patients (5.0%) assigned to lung-protective ventilation required noninvasive ventilation or intubation for acute respiratory failure, as compared with 34 (17.0%) assigned to nonprotective ventilation (relative risk, 0.29; 95% CI, 0.14 to 0.61; P=0.001). The length of the hospital stay was shorter among patients receiving lung-protective ventilation than among those receiving nonprotective ventilation (mean difference, -2.45 days; 95% CI, -4.17 to -0.72; P=0.006).

CONCLUSIONS:
As compared with a practice of nonprotective mechanical ventilation, the use of a lung-protective ventilation strategy in intermediate-risk and high-risk patients undergoing major abdominal surgery was associated with improved clinical outcomes and reduced health care utilization. (IMPROVE ClinicalTrials.gov number, NCT01282996.

 

[BLADEMDA]

Despite some great studies on this subject over the past 5 years we still don't know what the BEST ventilation strategy is for a particular patient in the operating room. Perhaps, each subgroup has their own best strategy? Or, are the variables so numerous we can't predict which group benefits the most a particular strategy? At this time there are just as many questions as answers which is why we must refrain from criticizing our colleagues doing a case (ASA 2) utilizing the time tested 10 ml/kg strategy with minimal to no PEEP.

While I myself have a good grasp of the literature from our Journals as well as the Critical Care literature the Operating room is not the ICU and we must refrain from proclaiming the low tidal Volume strategy in the operating room as proven fact. Is this the new Dogma of the 21st Century?


http://www.ncbi.nlm.nih.gov/pubmed/23542800

http://www.ncbi.nlm.nih.gov/pubmed/22661750

http://www.ncbi.nlm.nih.gov/pubmed/19933173

 

[Stank811]

Not much that I am aware of that suggest that lung protective strategies 4-8cc/kg (predictive body weight) with titrated PEEP results in more harm compared with "traditional" ventilation strategies 10-15cc/kg (PBW). Multiple studies suggest that you cause less inflammation to the lung which often seems to correlates with decreased pulmonary complications (upper abdominal surgery, CPB, OLV) in the peri-operative period if you use lung protective strategies....so what supports ventilating anyone with TV of 1200cc at a RR of 8 and no peep?

 

[Noyac]

I do exactly as you described. Lowish PEEP (5 for me), 6-8 ml/ kg, and a rate of 12 usually. I usually have ETCO2 around 35-45 excluding laproscopic cases. If the case was longer than 2 hrs then I may give some recruitment maneuvers.

I notice that in my group for all MD's we all have different styles of ventilation.

 

[BLADEMDA]

Not much that I am aware of that suggest that lung protective strategies 4-8cc/kg (predictive body weight) with titrated PEEP results in more harm compared with "traditional" ventilation strategies 10-15cc/kg (PBW). Multiple studies suggest that you cause less inflammation to the lung which often seems to correlates with decreased pulmonary complications (upper abdominal surgery, CPB, OLV) in the peri-operative period if you use lung protective strategies....so what supports ventilating anyone with TV of 1200cc at a RR of 8 and no peep?

As you can read from this thread I utilize a reduced TV strategy with PEEP; some of my colleagues are still using 10 ml/kg with no PEEP. While I think there are some studies suggesting benefit with a lower TV strategy combined with PEEP the evidence isn't quite there yet to describe it as "standard of care."


Goldenberg et al. summarize “that the ideal approach to intraoperative ventilation…remains unknown.” Taking into account that so many open questions remain, even without discussing the role of hypercapnia6 or inspiratory oxygen concentration,7 we believe that their conclusion cannot be overemphasized.

 

[BLADEMDA]

Not much that I am aware of that suggest that lung protective strategies 4-8cc/kg (predictive body weight) with titrated PEEP results in more harm compared with "traditional" ventilation strategies 10-15cc/kg (PBW). Multiple studies suggest that you cause less inflammation to the lung which often seems to correlates with decreased pulmonary complications (upper abdominal surgery, CPB, OLV) in the peri-operative period if you use lung protective strategies....so what supports ventilating anyone with TV of 1200cc at a RR of 8 and no peep?

I am aware of the studies which show decreased inflammation to the lung. But, not all the evidence is a crystal clear as you would like to believe. Here is a study done on pigs for example:


Anesth Analg. 2010 Jun 1;110(6):1652-60. doi: 10.1213/ANE.0b013e3181cfc416. Epub 2010 Jan 26.
Low tidal volume and high positive end-expiratory pressure mechanical ventilation results in increased inflammation and ventilator-associated lung injury in normal lungs.
Hong CM1, Xu DZ, Lu Q, Cheng Y, Pisarenko V, Doucet D, Brown M, Aisner S, Zhang C, Deitch EA, Delphin E.
Author information

Abstract
BACKGROUND:
Protective mechanical ventilation with low tidal volume (Vt) and low plateau pressure reduces mortality and decreases the length of mechanical ventilation in patients with acute respiratory distress syndrome. Mechanical ventilation that will protect normal lungs during major surgical procedures of long duration may improve postoperative outcomes. We performed an animal study comparing 3 ventilation strategies used in the operating room in normal lungs. We compared the effects on pulmonary mechanics, inflammatory mediators, and lung tissue injury.

METHODS:
Female pigs were randomized into 3 groups. Group H-Vt/3 (n = 6) was ventilated with a Vt of 15 mL/kg predicted body weight (PBW)/positive end-expiratory pressure (PEEP) of 3 cm H(2)O, group L-Vt/3 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 3 cm H(2)O, and group L-Vt/10 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 10 cm H(2)O, for 8 hours. Hemodynamics, airway mechanics, arterial blood gases, and inflammatory markers were monitored. Bronchoalveolar lavage (BAL) was analyzed for inflammatory markers and protein concentration. The right lower lobe was assayed for mRNA of specific cytokines. The right lower lobe and right upper lobe were evaluated histologically.

RESULTS:
In contrast to groups H-Vt/3 and L-Vt/3, group L-Vt/10 exhibited a 6-fold increase in inflammatory mediators in BAL (P < 0.001). Cytokines in BAL were similar in groups H-Vt/3 and L-Vt/3. Group H-Vt/3 had a significantly lower lung injury score than groups L-Vt/3 and L-Vt/10.

CONCLUSION:
Comparing intraoperative strategies, ventilation with high PEEP resulted in increased production of inflammatory markers. Low PEEP resulted in lower levels of inflammatory markers. High Vt/low PEEP resulted in less histologic lung injury.

 

[Planktonmd]

I give a tidal volume that does not produce a PIP higher than 20 cm H2O, that's it!
It's very stupid to think that the tidal volume should be a number derived from body weight.
I mean how on earth does body weight determine the amount of air that should enter the lungs?

 

[jwk]

No pressure-control fans? I haven't set tidal volumes on a vent in quite a while.

 

[deleted171991]

I give a tidal volume that does not produce a PIP higher than 20 cm H2O, that's it!
It's very stupid to think that the tidal volume should be a number derived from body weight.
I mean how on earth does body weight determine the amount of air that should enter the lungs?

That's a misconception that I also used to have.

However, the studies tend to show that there is no real barotrauma without volutrauma. As in the tidal volume is more important than the PIP or the plateau pressure.

Where do the numbers come from? From the average tidal volumes for spontaneous negative-pressure ventilation. They pretty much correlate with the IBW. Humans tend to breath at around 14-18 breaths/minute and less than 6 ml/kg.

Let me put it this way: if you take 8 ml/kg x 10-12 breaths/min and divide it by the physiologic 14-18 breaths/min, you get less than 6 ml/kg.

 

[deleted171991]

No pressure-control fans? I haven't set tidal volumes on a vent in quite a while.

Huge PCV fan here (and I don't have a volume-guarantee on my vents either). It's the more physiologic method of PPV.

 

[Noyac]

SIMV

 

[sevoflurane]

I use a flux capacitor with 1.21 GW...

 

[sevoflurane]

It just depends on the patient IMO. Some form of peep on everyone.

 

[Noyac]

So I for one have fully bought in to the "volutrauma" theory. I don't ventilate anyone with more than 8ml/kg anymore. I give everyone some PEEP. Some need more PEEP than others but everyone gets some.

I use SIMV because it allows me to paralyze less. I rarely ever have a pt "buck" on the vent any longer. That is a thing of the past. Even with using less paralysis these days I don't get pts fighting the vent.

How do I know this works well? Or better? Well taking a page out of Blade's book, I've been doing this for a long time now and I have thousands of anesthetics under my belt. This is the system I have come up with that works best for me. It is smooth and pts do extremely well. But it's not just me that says this. Every surgeon and nurse I work with will agree. I know this comes across as arrogant but so be it. If I can give someone a pearl the it is worth it.

 

[deleted171991]

I use SIMV because it allows me to paralyze less. I rarely ever have a pt "buck" on the vent any longer. That is a thing of the past. Even with using less paralysis these days I don't get pts fighting the vent.

Now take the next step, and switch to PCV. Because it's physiologic (just look at the flow curves for PCV and spontaneous ventilation), plus it allows overbreathing, you get the no-bucking effect on pressure-control, too.

 

[BLADEMDA]

http://forums.studentdoctor.net/threads/pressure-control-volume-guarantee.839564/


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4057867/

 

[BLADEMDA]

My preference is for PC-VG mode:


ORIGINAL ARTICLE
Year : 2014 | Volume : 7 | Issue : 2 | Page : 96-100
Does pressure-controlled ventilation-volume guaranteed differ from pressure-controlled ventilation in anesthetized patients

Nermin S. Boules, Mohamed A El Ramely
Department of Anesthesiology and Pain Management, National Cancer Institute, Cairo University, Cairo, Egypt



Background
General anesthesia causes depression of both respiratory centers and respiratory muscles. Hence, patients under general anesthesia require ventilatory support to maintain arterial oxygenation and eliminate carbon dioxide. Mechanical ventilation can improve patients outcome. The purpose of this study was to determine whether pressure-controlled ventilation-volume guaranteed (PCV-VG) provide better oxygenation than pressure-controlled ventilation (PCV) in anesthetized patients.
Patients and methods
A total of 30 patients scheduled for abdominal cancer surgery under general anesthesia were enrolled in the study. Mechanical ventilation was started with PCV for 60 min then PCV-VG was applied to all patients with the same parameters, targeting the obtained tidal volume (Vt). Arterial blood pressures, heart rate, ETCO 2 , SpO 2 , pH, PaCO 2 , and PaO 2 were measured after 60 min of intubation during PCV and after 60 min of initiation of PCV-VG. Vt, mean airway pressure, and peak airway pressure (during PCV-VG) were recorded. Oxygenation index calculation was performed at the preset times.
Results
All parameters were comparable with no significant difference between both modes of ventilation in anesthetized patients ( P ≥ 0.05).
Conclusion
While maintaining constant Vt and I/E ratio, there were no significant differences in respiratory and ventilatory parameters, and also the oxygenation index was comparable between both PCV and PCV-VG modes of ventilation.

 

[BLADEMDA]

Int J Clin Exp Med. 2014 Aug 15;7(8):2242-7. eCollection 2014.
Ventilation during laparoscopic-assisted bariatric surgery: volume-controlled, pressure-controlled or volume-guaranteed pressure-regulated modes.
Dion JM1, McKee C1, Tobias JD1, Sohner P1, Herz D2, Teich S3, Rice J1, Barry ND1, Michalsky M3.
Author information

Abstract
INTRODUCTION:
Managing ventilation and oxygenation during laparoscopic procedures in severely obese patients undergoing weight loss surgery presents many challenges. Pressure-controlled ventilation, volume-guaranteed (PCV-VG) is a dual-control mode of ventilation and an alternative to pressure (PC) or volume (VC) controlled ventilation. PCV-VG features a user-selected tidal volume target, that is auto-regulated and pressure controlled. We hypothesized that PCV-VG ventilation would provide improved oxygenation and ventilation during laparoscopic bariatric surgery with a lower peak inflating pressure (PIP) than either PC or VC ventilation.

METHODS:
This was a prospective cross-over cohort trial (n = 20). In random sequence each patient received the three modes of ventilation for 20 minutes during the laparoscopic portion of the procedure. For all modes of ventilation the goal tidal volume was 6-8 mL/kg, and the respiratory rate was adjusted to achieve normocarbia. The PIP, exhaled tidal volume, respiratory rate, and oxygen saturation were recorded every five minutes. At the end of 20 minutes, an arterial blood gas was obtained. Data were analyzed using a paired t-test.

RESULTS:
PCV-VG and PC ventilation both resulted in significantly lower PIP (cmH2O) than VC ventilation (30.5 ± 3.0, 31.6 ± 4.9, and 36.3 ± 3.4 mmHg respectively; p < 0.01 for PCV-VG vs. VC and PC vs. VC). There was no difference in oxygenation (PaO2), ventilation (PaCO2) or hemodynamic variables between the three ventilation modes.

CONCLUSIONS:
In adolescents and young adults undergoing laparoscopic bariatric surgery, PCV-VG and PC were superior to VC ventilation in their ability to provide ventilation with the lowest PIP.

 

[lunaire]

I stick somewhat close to the ARDS net protective lung ventilation: initially start with 8mL/kg, rate of 12. Weight used is ideal body weight, so it's actually more height based, which should predict the physiologic lung volume better than actual weight. If the EtCO2 is lower than goal, I would decrease the TV until 6mL/kg, if higher than goal, I increase the RR, with TV at max 8mL/kg.

My hospital is a bariatric referral center, so >50% obese. We basically have to use PCV to get the pressure below 30cmH2O. For the patients with BMI >50, we sometimes have to decrease the I:E ratio & give high insp. flow to keep EtCO2 sensible.

WIth that said, some other people just go VC at 500, allow PIP to go up to 40. They haven't had any significant comorbidities, afaik.

 

[Planktonmd]

That's a misconception that I also used to have.

However, the studies tend to show that there is no real barotrauma without volutrauma. As in the tidal volume is more important than the PIP or the plateau pressure.

Where do the numbers come from? From the average tidal volumes for spontaneous negative-pressure ventilation. They pretty much correlate with the IBW. Humans tend to breath at around 14-18 breaths/minute and less than 6 ml/kg.

Let me put it this way: if you take 8 ml/kg x 10-12 breaths/min and divide it by the physiologic 14-18 breaths/min, you get less than 6 ml/kg.

Trying to predict positive pressure tidal volumes from spontaneous tidal volumes makes no sense, completely different physiology.
And it's also funny that people can give dissertations about volume trauma and the advantages of smaller volumes then they say that their preferred mode of ventilation is pressure control !!!
If you think that pressure is not relevant why would you use PC???

 

[deleted171991]

Trying to predict positive pressure tidal volumes from spontaneous tidal volumes makes no sense, completely different physiology.
And it's also funny that people can give dissertations about volume trauma and the advantages of smaller volumes then they say that their preferred mode of ventilation is pressure control !!!

As I said, I used to think like you, until recently. The reason volutrauma is more important than barotrauma are the studies comparing them. It's the Vt that really matters. I too did not expect this conclusion. I used to think that me ventilating 8-10 ml/kg at a PIP of 20 is better than others ventilating 6-8 ml/kg at 25. But, in the end, you are distending the alveoli more with PCV than VCV, for the same PIP, because PCV is more efficient (not surprisingly, since the flow and pressure curves are closer to NPV). I would expect that PCV simply generates less turbulence in the conducting airways.

I bet that both PCV and VCV end up generating about the same amount of intra-alveolar pressure and volume to for the same Vt. And probably that unmeasurable intra-alveolar pressure is the one responsible for trauma, not the PIP, which includes a lot of variables related to the conducting airways. At least that would be the logical explanation why measured tidal volumes (which don't depend on how one insufflates) correlate better with outcomes than peak pressures (which are clearly dependent on the type of flow-curve and the turbulence created).

If you think that pressure is not relevant why would you use PC???

I use pressure control because:
1. it needs smaller pressures to achieve the same volume, hence limiting barotrauma, too (at least theoretically), although I am not sure anymore that there is such a thing as barotrauma without volutrauma;
2. it has the same pressure-/flow-curves as spontaneous breathing, so it's more physiologic;
3. it allows the patient to overbreathe the vent.

 

[BLADEMDA]

I utilize PC with volume guarantee for many of my ASA3 and 4 patients:

1. I can dial in my desired tidal volume of 7-8 ml/kg with a peep of 5-6
2. PC reduces the peak pressure to the lung compared to volume control
3. Oxygenation may be improved with PC vs VC

 

[BLADEMDA]

http://www3.gehealthcare.com/~/medi...ure-control-ventilation-volume-guaranteed.pdf

This is worth reading. Take a look

 

[Planktonmd]

As I said, I used to think like you, until recently. The reason volutrauma is more important than barotrauma are the studies comparing them. It's the Vt that really matters. I too did not expect this conclusion. I used to think that me ventilating 8-10 ml/kg at a PIP of 20 is better than others ventilating 6-8 ml/kg at 25. But, in the end, you are distending the alveoli more with PCV than VCV, for the same PIP, because PCV is more efficient (not surprisingly, since the flow and pressure curves are closer to NPV). I would expect that PCV simply generates less turbulence in the conducting airways.

I bet that both PCV and VCV end up generating about the same amount of intra-alveolar pressure and volume to for the same Vt. And probably that unmeasurable intra-alveolar pressure is the one responsible for trauma, not the PIP, which includes a lot of variables related to the conducting airways. At least that would be the logical explanation why measured tidal volumes (which don't depend on how one insufflates) correlate better with outcomes than peak pressures (which are clearly dependent on the type of flow-curve and the turbulence created).

I use pressure control because:
1. it needs smaller pressures to achieve the same volume, hence limiting barotrauma, too (at least theoretically), although I am not sure anymore that there is such a thing as barotrauma without volutrauma;
2. it has the same pressure-/flow-curves as spontaneous breathing, so it's more physiologic;
3. it allows the patient to overbreathe the vent.

I think you should have waited for a few more studies before changing your mind
Now you might have to change your mind again when studies come out proving the exact opposite concerning pressure versus volume trauma.

 

[Planktonmd]

http://www3.gehealthcare.com/~/medi...ure-control-ventilation-volume-guaranteed.pdf

This is worth reading. Take a look

I like PC-VG and I think it offers the advantages of both VC and PC

 

[Depakote]

Here is how I do it:

Typical ASA 3 patient (which is my usual) gets 7 ml/kg (predicted body weight) with a Peep of 6. I don't always stress a recruitment maneuver to the midlevels but I encourage at least one.

I figure some of you are sticking with the old strategy of 10-12 ml/kg with zero peep while others are utilizing 6 mg/kg with Peep of 8-10 plus regular interval recruitment maneuvers.

This is how I've been trained. I usually run 6-8ml/kg with 5 (PEEP) and occasional recruitment breaths. FiO2 40-50% as tolerated.

I can't think of a single attending at my training program who wants a tidal volume of 10ml/kg or greater on an adult.

 

[deleted171991]

I think you should have waited for a few more studies before changing your mind
Now you might have to change your mind again when studies come out proving the exact opposite concerning pressure versus volume trauma.

It really doesn't matter, because I pay attention to both. I ventilate both with low PIP and low Vt. All I did was to increase the RR.

I like PC-VG and I think it offers the advantages of both VC and PC

I agree. Unfortunately, the vents I work with now don't have it, so my vigilance is the volume guarantee. I actually like it this way.

 

[pgg]

I use pressure control because:
1. it needs smaller pressures to achieve the same volume, hence limiting barotrauma, too (at least theoretically), although I am not sure anymore that there is such a thing as barotrauma without volutrauma;
2. it has the same pressure-/flow-curves as spontaneous breathing, so it's more physiologic;
3. it allows the patient to overbreathe the vent.

I don't find your argument very convincing.

I don't think (1) is really true for the most part, if you use sufficiently long inspiration times, volumes in the 6 mL/kg range, and recognize that plateau pressure is the important number. PIP is nearly irrelevant; that pressure is not what the alveoli see. You're not causing baro/volutrauma above the bronchiole level. I can't remember the last time I had trouble delivering low-volume, acceptable pressure breaths on VC ... and then realized any benefit to switching to PC. The answer in that case is usually permissive hypercarbia.

I don't know what you mean by (2). Same pressure curve as spontaneous breathing? How that? PC is positive pressure ventilation, spontaneous breathing is negative pressure. The flow curves for PC and spontaneous resemble each other, in that flow isn't constant the way VC is. It may be intuitive to think that a controlled ventilation curve that sorta generally resembles spontaneous ventilation is somehow safer, but the history of medicine is littered with intuitive ideas that just ain't so.

(3) is irrelevant. Every modern ventilator allows patients to breathe over the set rate on volume control too. What kind of stone age 1990s bellows-driven machinery are you using?


The best argument I've ever heard for PC ventilation is that old ventilators weren't very good at delivering small tidal volumes. When the machine isn't precise, and dead space and tubing compliance are a large fraction of the desired TV, then pressure control is certainly safer. I think this is why it's so popular amongst older anesthesiologists ... 15-20 years ago, they had a good reason not to use VC.

 

[Mad Jack]

Here is how I do it:

Typical ASA 3 patient (which is my usual) gets 7 ml/kg (predicted body weight) with a Peep of 6. I don't always stress a recruitment maneuver to the midlevels but I encourage at least one.

I figure some of you are sticking with the old strategy of 10-12 ml/kg with zero peep while others are utilizing 6 mg/kg with Peep of 8-10 plus regular interval recruitment maneuvers.

 

[Urzuz]

Regarding the use of pressure control, I think it's important to note that all studies that I am aware of (ARDS studies or even the NEJM article that Blade posted regarding low tidal volumes intraoperatively) showing an outcome difference have been done using volume control settings. While PC may potentially improve oxygenation at lower pressures, etc, as far as I know, no outcomes (morbidity/mortality) have been shown to be different using pressure control (versus they HAVE been shown using volume control). I'm not saying that outcomes wouldn't be improved if a study was done, because intuitively it would make sense that they would be...but we all know how dangerous "if A=B, and B=C, then A=C" statements are in medicine. Just my 2 cents.

Two more quick things: 1) I'm a fan of volume control in almost all cases unless I'm having difficulty ventilating the patient and I think permissive hypercapnea may be damaging to that particular patient's physiology, 2) I want to stress what Plankton already mentioned above for new residents and others out there who haven't grasped it -- your lungs don't grow proportionally with your belly!!! (ie: ml/kg refers to ideal body weight for the patient's height and gender, not actual body weight! You are doing your patients a disservice if you're ventilating the 5'0" 400 lb lady at 600 ml tidal volumes!).

 

[deleted171991]

I don't find your argument very convincing.

I don't think (1) is really true for the most part, if you use sufficiently long inspiration times, volumes in the 6 mL/kg range, and recognize that plateau pressure is the important number. PIP is nearly irrelevant; that pressure is not what the alveoli see. You're not causing baro/volutrauma above the bronchiole level. I can't remember the last time I had trouble delivering low-volume, acceptable pressure breaths on VC ... and then realized any benefit to switching to PC. The answer in that case is usually permissive hypercarbia.

What is acceptable pressure? For PCV, PIP = PPlat, so I don't have to worry about measuring Pplat.

I don't know what you mean by (2). Same pressure curve as spontaneous breathing? How that? PC is positive pressure ventilation, spontaneous breathing is negative pressure.

Got me here. I was referring to the shape of the curve.

(3) is irrelevant. Every modern ventilator allows patients to breathe over the set rate on volume control too. What kind of stone age 1990s bellows-driven machinery are you using?

The Aestiva 5 ventilators from my residency were associated with more bucking during VCV than PCV. (I am talking about CMV here, not SIMV.)

The best argument I've ever heard for PC ventilation is that old ventilators weren't very good at delivering small tidal volumes. When the machine isn't precise, and dead space and tubing compliance are a large fraction of the desired TV, then pressure control is certainly safer. I think this is why it's so popular amongst older anesthesiologists ... 15-20 years ago, they had a good reason not to use VC.

Funny thing is that I was trained mostly with VCV. I haven't used PCV until I became an attending. Which reminds me of another advantage:

4. Because it requires lower pressures, for LMAs, PCV is easier to use than VCV.

 

[BLADEMDA]

Evidence based medicine suggests that PC-Volume guaranteed Ventilation may be better for one lung Ventilation and Bariatric Surgery/Obese Patients undergoing Laparoscopic/Robotic surgery.

For other types of surgery we are merely speculating that one type of ventilation (VC) with low Vt vs another type (PC) with low Vt makes any difference at all.


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4057867/


http://www.ncbi.nlm.nih.gov/pubmed/25232415

http://www.ncbi.nlm.nih.gov/pubmed/18407943

http://medind.nic.in/iad/t12/i3/iadt12i3p276.htm

 

[BLADEMDA]

PCV with VG is an excellent mode to try when you are having trouble with oxygenating an extremely, morbidly obese patient.

1. Try to re-exapand the alveoli with recruitment maneuvers. Sometimes very high PIP is needed for the expansion in this population.

http://bariatrictimes.com/mechanical-ventilation-in-patients-with-morbid-obesity/

2. Try switching to PC-VG mode on your ventilator. This has worked for me frequently.

https://books.google.com/books?id=bnOdfmNf9jAC&pg=PA306&lpg=PA306&dq=pressure control ventilation for obese patients&source=bl&ots=L228yvE_24&sig=Av2g6MSxifiikiWIR4g0jIT9RBM&hl=en&sa=X&ei=BhvEVKyeGMeMNvijgsgI&ved=0CDQQ6AEwBTgU#v=onepage&q=pressure control ventilation for obese patients&f=false
3. Switch to 1:1 (I:E) ratio on your ventilator.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3657935/

 

[pd4emergence]

This is one of my pet peeves. Just about every room I start, I turn down the vent. press/volume or both. I think that volume/pressure matters in certain patients. I feel that trauma and this at risk for sepsis/sirs should probably be ventilated in the 5-8cc/kg category. The problem is (excluding trauma) a lot of the time its hard to know who is gonna be at risk for sepsis/sirs. Because of this I try to ventilate in the 5-8cc category with 4-6 of peep for everybody. It's easy to do. Doesn't seem to cause any harm. Makes you actually pay attention to your machine and may be beneficial.

 

[jwk]

We don't have PC-VG available on our vents - hell, half of them don't have pressure support, just PC or VC.

I run just about all of my patients on PC (or PSV with an LMA). I start most patients at 12-15 cmH2O, add a little PEEP on most, and adjust everything from there based on EtCO2 and SaO2. On laparoscopic/robotic cases, I frequently roll back the IE ratio to 1:2.5 or even 1:1. I note the Vt, but in most cases, it's just not a concern, except that I'm surprised how well a lot of patients ventilate with fairly low pressures AND volumes. Recruitment maneuvers - fancy name for a "sigh" breath that I was taught more than 35 years ago. We used to have vents with a sigh function - they'd deliver a Vt x1.4 breath every few minutes. Some vents also had a sigh button on them.

 

[scudrunner]

Seems all risk and no benefit to ventilate with 10mL/kg or more- it's not physiologic.

 

[BLADEMDA]

Anaesthesia. 2012 Sep;67(9):999-1008. doi: 10.1111/j.1365-2044.2012.07218.x. Epub 2012 Jun 18.
A multicentre observational study of intra-operative ventilatory management during general anaesthesia: tidal volumes and relation to body weight.
Jaber S1, Coisel Y, Chanques G, Futier E, Constantin JM, Michelet P, Beaussier M, Lefrant JY, Allaouchiche B, Capdevila X,Marret E.
Author information

Abstract
We conducted an observational prospective multicenter study to describe the practices of mechanical ventilation, to determine the incidence of use of large intra-operative tidal volumes (≥10 ml.kg(-1) of ideal body weight) and to identify patient factors associated with this practice. Of the 2960 patients studied in 97 anaesthesia units from 49 hospitals, volume controlled mode was the most commonly used (85%). The mean (SD) tidal volume was 533 (82) ml; 7.7 (1.3) ml.kg(-1) (actual weight) and 8.8 (1.4) ml.kg(-1) (ideal body weight)). The lungs of 381 (18%) patients were ventilated with a tidal volume>10 ml.kg(-1) ideal body weight. Being female (OR 5.58 (95% CI 4.20-7.43)) and by logistic regression, underweight (OR 0.06 (95% CI 0.01-0.45)), overweight (OR 1.98 (95% CI 1.49-2.65)), obese (OR 5.02 (95% CI 3.51-7.16)), severely obese (OR 10.12 (95% CI 5.79-17.68)) and morbidly obese (OR 14.49 (95% CI 6.99-30.03)) were the significant (p ≤ 0.005) independent factors for the use of large tidal volumes during anaesthesia.

Anaesthesia © 2012 The Association of Anaesthetists of Great Britain and Ireland.

 

[pgg]

What is acceptable pressure? For PCV, PIP = PPlat, so I don't have to worry about measuring Pplat.

To me, acceptable depends on a number of factors. Obesity, steep trendelenberg, insufflation, lung health, the procedure, duration of surgery, etc. Generally, I prefer under 20, will tolerate under 30, will make changes when it gets into the 30s. (Plateau pressures.)

I've never found measuring plateau pressure to be trouble. Some vents will do it for you. Though I've found, on Dragers, it doesn't always pick out the difference between PIP and plateau if you leave the inspiratory pause at the default 10%. Sometimes needs 20%.

 

[Random Anesthesiologist]

I do exactly as you described. Lowish PEEP (5 for me), 6-8 ml/ kg, and a rate of 12 usually. I usually have ETCO2 around 35-45 excluding laproscopic cases. If the case was longer than 2 hrs then I may give some recruitment maneuvers.

I notice that in my group for all MD's we all have different styles of ventilation.

I do the same, adjusting rate for EtCO2

 

[fakin' the funk]

I do the same, adjusting rate for EtCO2

This.

 

[fakin' the funk]

Seems all risk and no benefit to ventilate with 10mL/kg or more- it's not physiologic.

This.

The data on small tidal volumes in the ICU comes from patients WHO HAVE ARDS! Back in the day that was a 40% mortality diagnosis.

Obviously many, if not most, of our OR patients have normal lungs or are undergoing low or moderately "lung-injuring' procedures, and our mortality is somewhat lower than 40%. I doubt you could ever show a benefit to a certain ventilatory strategy in this unselected population.

That's where the Futier study from NEJM steps in. They selected for a medium-to-quite sick population undergoing what might be expected to be a "lung-injuring" associated type of procedure. And they showed a significant benefit.

 

[Noyac]

I do the same, adjusting rate for EtCO2

What's your ETCO2 target? Generally speaking.

 

[fakin' the funk]

Here is how I do it:

Typical ASA 3 patient (which is my usual) gets 7 ml/kg (predicted body weight) with a Peep of 6. I don't always stress a recruitment maneuver to the midlevels but I encourage at least one.

I figure some of you are sticking with the old strategy of 10-12 ml/kg with zero peep while others are utilizing 6 mg/kg with Peep of 8-10 plus regular interval recruitment maneuvers.

And just emphasize: IDEAL BODY WEIGHT!