The document discusses biphasic cuirass ventilation (BCV) as a treatment for various forms of respiratory failure, emphasizing its benefits such as improved gas exchange, decreased work of breathing, and reduced hospitalization rates. Studies also reveal the efficacy of combining positive and negative ventilation strategies, particularly in patients with acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). Overall, BCV and related strategies show promise in enhancing patient outcomes by preventing intubations and decreasing medical costs.

1. Biphasic Cuirass Ventilation for
Respiratory Failure and ARDS

2. Open Lung Concept
With BCV
• Optimizing lung volume by recruiting and
stabilizing unstable airways and lung units with
negative lung inflation
• Most homogeneous distribution of ventilation
possible
• Benefits:
– Improved pulmonary compliance
– Improved gas exchange
– Decreased work of breathing
– Better flow of secretions
– Decreased shunt and deadspace
– Improved pulmonary perfusion

3. Acute/Chronic Respiratory Failure
• pO2 <60 mm Hg or SpO2 (pulse oximetry)
<91% breathing room air
• pCO2 >50 mm Hg and pH <7.35 (hypercapnic)
• pH partially or fully compensated if chronic
and advancing from stable to unstable with
increased symptoms
• P/F ratio (pO2 / FIO2) <300
• pO2 decrease or pCO2 increase by 10 mm Hg
from baseline (if known).
https://acphospitalist.org/archives/2013/11/coding.htm

4. COPD

5. COPD Case Study
• 75 yo f
• Hx chronic respiratory failure, COPD, Cor Pulmonale
• Admitted with respiratory distress
• CO2 retention and dyspnea increased on floor
• Moved to ICU with high potential intubation-trach
• Severe mask intolerance
• BCV initiated with near immediate improvement of
dyspnea
• BCV utilized through to acute discharge, intubation/trach
avoided
• BCV utilized at LTAC then SNF
• High potential for short term readmission avoided

7. Readmission Prevention
• Long-term effects of a hospital-based PR program coupled with NPV support in
patients with COPD on clinical outcomes evaluated.
• One hundred twenty-nine patients with COPD were followed up for more than 5
years
• NPV group receiving the support of NPV (20–30cm H2O delivery pressure for 60
min) and unsupervised home exercise program of 20 to 30 min daily walk
• Control group only received unsupervised home exercise program.
• Pulmonary function tests and 6 min walk tests (6MWT) were performed every 3 to
6 months. Emergency room (ER) visits and hospitalization with medical costs were
recorded.
• ER exacerbations and hospitalizations decreased by 66% (P<0.0001) and 54%
(P<0.0001) in the NPV group, respectively.
• Patients on PR program coupled with NPV had a significant reduction of annual
medical costs
• Our hospital-based multidisciplinary PR coupled with NPV reduced yearly decline
of lung function, exacerbations, and hospitalization rates, and improved walking
distance and medical costs in patients with COPD during a 5-year observation

10. decreased by 66% decreased by 54%

11. Carpagnano GE, Sabato R, Lacedonia D, Di Gioia
R, Saliani V, Vincenzi U, Foschino-Barbaro MP
Department of Medical and Surgical Sciences, Institute of Respiratory
Diseases, University of Foggia, ItalybIntermediate Intensive
Respiratory Disease Unit, D'Avanzo Hospital, Foggia, Italy
New non invasive ventilator strategy applied to
COPD patients in acute ventilator failure
Pulmonary Pharmacology & Therapeutics (2017), doi: 10.1016/j.pupt.2017.08.009

12. • Abstract Introduction: There is no evidence in the literature regarding the
combined use of positive ventilation with negative ventilation. A recent study
reported that the two techniques can be combined in patients with ARDS, who
undergo ventilatory support for severe acute respiratory failure (ARF). There is
experience of non-invasive ventilation in patients with chronic respiratory
diseases and ARF. The aim of this study was to test the efficacy of a non-
invasive ventilatory strategy based on the combined use of negative (N) and
positive ventilation (P) in bi-level mode (PN). Methods: We enrolled 8 patients
with severe COPD exacerbations and exacerbated chronic respiratory failure
admitted in a monitored setting of an intermediate-intensive respiratory Unit.
Results: Patients underwent combined positive/negative ventilation and at
different times, in place of the two singular ventilation modes (P and N). After
each cycle, in the combined P/N ventilatory mode, gas exchanges were
significantly increased compared to the two singular P/N mode: pH (7.42 vs
7.40 and 7.40); PCO2 (85.01 vs 72.05 and 66.81 mmHg); FiO2/PO2 (488.75 vs
352.62 and 327.87). All patients well tolerated the application of the double
ventilation mode. Conclusions: In conclusion, the use of dual mode ventilation
appears well tolerated and superior to the individual modes in patients with
COPD exacerbations and ARF.
Carpagnano GE, Sabato R, Lacedonia D, Di Gioia R, Saliani V, Vincenzi U, Foschino-Barbaro MP, New non invasive ventilator strategy applied to COPD patients in
acute ventilator failure, Pulmonary Pharmacology & Therapeutics (2017), doi: 10.1016/j.pupt.2017.08.009.

13. Pulmonary Pharmacology & Therapeutics (2017), doi: 10.1016/j.pupt.2017.08.009

14. Findings
• Gas exchanges were significantly increased
compared to the two singular
• All patients well tolerated the application of the
double ventilation mode
• Conclusion: The use of dual mode ventilation
appears well tolerated and superior to the
individual modes in patients with COPD
exacerbations and ARF
Pulmonary Pharmacology & Therapeutics (2017), doi: 10.1016/j.pupt.2017.08.009

15. Asthma

16. BCV cited as a Benefit for Asthma
#K59 - INVESTIGATION OF THE EFFICACY OF BIPHASIC CUIRASS
VENTILATION FOR CHILDREN HOSPITALIZED WITH A MODERATE
BRONCHIAL ASTHMA ATTACK
Minato TM.1, Okada KO.2
1. Pediatrics, Toyooka Hospital Toyooka, Japan
2. Pediatrics, Okada Kodomonomori Clinic Saitama, Japan
We have seen that the combination of CN and SC modes can
deliver rapid and effective relief for moderate exacerbations of
bronchial asthma (BA), characterized by limited airflow due to
contraction of bronchial smooth muscle, swelling of respiratory
mucosa, and increased secretions. Therefore, we investigated
the efficacy of BCV.
PEDIATRIC PULMONOLOGY Volume 51 • Supplement 43 • June 2016 Proceedings #K59 pp S83

17. BCV cited as a Benefit for Asthma
14 patients admitted to our hospital for moderate BA
attacks and subsequently treated with BCV as an add-
on to conventional BA therapy (Group A).
The results of these patients were compared to those
of a control group consisting of 15 patients hospitalized
for moderate BA attacks before the hospital had
introduced the use of BCV (Group B).
PEDIATRIC PULMONOLOGY Volume 51 • Supplement 43 • June 2016 Proceedings #K59 pp S83

18. Results:
•The BCV group showed a significant improvement in both
HR Group A: 26.2/min Group B:13.9/min
RR Group A: 13.3 /min Group B: 6.4 /min
•Number of days on oxygen was significantly shorter in BCV
group
O2 days Group A: 2.9 ± 1.3 days Group B: 5.2 ± 1.8 days
•Length of hospitalization was significantly shorter in the
BCV group
Hosp days Group A: 5.7 ± 1.7 days, Group B: 7 ± 1.4 days
PEDIATRIC PULMONOLOGY Volume 51 • Supplement 43 • June 2016 Proceedings #K59 pp S83

19. BCV cited as a Benefit for Asthma
Discussion:
BCV as an add-on to conventional therapy for pediatric
BA attacks enabled significant stabilization of the
patients’ cardio respiratory condition from the day after
commencement.
Furthermore, BCV reduced the length of hospitalization
and oxygen administration and proved useful from a
health economic perspective.
Conclusion: BCV is effective for moderate BA attacks.
PEDIATRIC PULMONOLOGY Volume 51 • Supplement 43 • June 2016 Proceedings #K59 pp S83

20. Negative-Pressure Ventilation Better
Oxygenation and Less Lung Injury
• Francesco Grasso, Doreen Engelberts, Emma
Helm, Helena Frndova, Steven Jarvis, Omid
Talakoub, Colin McKerlie, Paul Babyn, Martin
Post & Brian P. Kavanagh from Hospital for Sick
Children in Toronto
• American Journal Of Respiratory And Critical
Care Medicine VOL 177 pp412-418, 2008

21. Negative-Pressure Ventilation Better
Oxygenation and Less Lung Injury
• Rationale: Conventional positive-pressure ventilation
delivers pressure to the airways; in contrast, negative
pressure is delivered globally to the chest and abdomen.
• Objectives: To test the hypothesis that ventilation with
negative pressure results in better oxygenation and less
injury than with positive pressure.
• Methods: Anesthetized, surfactant-depleted rabbits were
ventilated for 2.5 hours in pairs (positive or negative).
Tidal volume was 12 ml /kg, normocapnia was
maintained by adjusting respiratory rate, and FIO2 was
1.0.

22. Lung Inflation via TPP
In Healthy Lungs
= TPP = Same VT
whether TPP
– or +

23. In Sick Lungs
Not So Simple
• Lung inflation is mal-distributed due to
heterogeneous lung obstruction and injury
patterns
• Much more so with + lung inflation than - lung
inflation
• Same volume exchange with + lung inflation
more injurious than - lung inflation
• Same volume exchange with - lung inflation
results in better oxygenation

24. 5 Experimental Series Were Performed
• Series 1: Lung Injury and Oxygenation
• Series 2: Global Pulmonary Perfusion
• Series 3: Regional Pulmonary Perfusion
• Series 4: Transpulmonary Pressures, Lung
Volumes, and Oxygenation
• Series 5: CT Scan

25. Series 1: Lung Injury and Oxygenation
With Negative Lung Inflation
• Oxygenation significantly better
• Significantly decreased PaCO2-PetCO2
gradient due to decreased dead space
ventilation
• Composite histologic lung injury score
significantly lower

28. Series 2: Global Pulmonary Perfusion
“with the negative pressure chest device, the global
pulmonary perfusion was significantly greater”

29. Series 3: Regional Pulmonary Perfusion
• Cuirass could conceivably augment right ventricular
preload thereby increase lung perfusion and
improve oxygenation

30. Series 4: Transpulmonary Pressures,
Lung Volumes, and Oxygenation
• The transpulmonary pressure generated by
negative end expiratory pressure was consistently
less than that generated for a comparable level of
PEEP.
• For given levels of transpulmonary pressure, the
overall EELV achieved was consistently greater
when distension was negative versus positive
pressure.
• Finally, for a given level of EELV, the resultant
PaO2 was greater where the EELV was achieved
by NPV compared with PPV

31. Series 5: CT Scan
• The spatial differences were striking, with dependent
atelectasis persisting over most of the respiratory cycle in
PPV. Such patterns have previously been reported in
patients undergoing PPV in the setting of acute lung injury
• In contrast, with NPV, we observed a different topographic
distribution, in which normally aerated lung volumes were
greater and atelectasis was reduced.
• The findings in the current study are similar to the altered
distribution of lung volume as has been demonstrated for
ventilation in the prone versus supine position

32. Spatial Differences Striking
Less dependent atelectasis over breath cycle

33. Clinical Implications
• The clinical implications of any approach that
improves oxygenation or diminishes lung
injury are potentially very great.

34. Conclusion
• Use-or incorporation- of NPV should be
reinvestigated in the clinical context in which
oxygenation is problematic or lung injury is
likely

35. BCV Case Studies
• 84 y.o. M with laryngeal cancer and R apical mass with nearly complete R
lung atelectasis on AM chest X-ray.
• BCV initiated with goal of increasing aeration of R lung and improving
atelectasis.
• BCV started with CNEP of -30 for 30 minutes to initiate lung recruitment.
• Secretion clearance treatment executed for 35 minutes with results of
production of copious amounts of dark beige sputum.
• CNEP resumed after secretion clearance at -20 for 1.5 hrs at which time
secretion clearance and cough assist was repeated.
• Sputum production: large volumes of cream colored suctioned.
• Patient was maintained on CNEP of -28 pending afternoon chest X-ray.
• Pre and post 3.5 hours of BCV rad studies below.

36. BCV Case Studies

37. P/F Ratio
• PO2/FiO2
• P/F ratio <300 is equivalent to a pO2 <60 mm
Hg on room air (acute respiratory failure)
• P/F ratio <250 is equivalent to a pO2 <50 mm
Hg on room air (severe respiratory failure)
• P/F ratio <200 is equivalent to a pO2 <40 mm
Hg on room air (extreme respiratory failure)
https://acphospitalist.org/archives/2013/11/coding.htm

38. Types of respiratory failure.
C. Roussos, and A. Koutsoukou Eur Respir J 2003;22:3s-14s

41. The Role of Biphasic Cuirass
Ventilation in Acute Respiratory
Failure
• Retrospective review of 41 cases of patients with
Respiratory Failure ventilated with BCV
• From various sources including a patient with
ARDS with a VAP for whom bronchoscopic
suctioning would not clear obstruction, but BCV
with secretion clearance was able to recruit the
lung
• CNEP was able to prevent intubation for COPD
patients probably due to decreased WOB and
deadspace ventilation

42. Alveolar Recruitment
American Journal of Respiratory and Critical Care Medicine, May 2007 A435

46. Intubation Avoidance 95%
• 258 consecutive patients with acute respiratory failure on chronic
respiratory disorders
• (77%) were treated exclusively with non-invasive mechanical
ventilation (40% with NPV, 23% with NPPV, and 14% with the
sequential use of both)
• In patients in whom NPV or NPPV failed, the sequential use of the
alternative non-invasive ventilatory technique allowed a significant
reduction in the failure of non-invasive mechanical ventilation (from
23.4 to 8.8%, p=0.002, and from 25.3 to 5%, p=0.0001, respectively)
• the hospital mortality (21%) was lower than that estimated by
APACHE II score (28%)
CONCLUSIONS:
• Using NPV and NPPV it was possible in clinical practice to avoid
endotracheal intubation in the large majority of unselected
patients with acute respiratory failure on chronic respiratory
disorders needing ventilatory support. The sequential use of both
modalities may increase further the effectiveness of non-invasive
mechanical ventilation.

47. Similar Results With HFO2
• BCV’s ability to work synergistically with the
high flow cannula systems can make both
devices more effective.
• Improvement often more quickly than
expected
• This combination may be your most powerful
1-2 punch for respiratory support ever. This
pair can dramatically decrease intubations
• Saving the bigger guns of PPV brought in to
replace the nasal device when failure
escalates.

48. Acute respiratory distress syndrome
• Acute respiratory distress syndrome (ARDS) is
a life-threatening lung condition that prevents
enough oxygen from getting to the lungs and
into the blood. Infants can also have
respiratory distress syndrome.
https://medlineplus.gov/ency/article/000103.htm

49. Acute respiratory distress syndrome
Causes
• ARDS can be caused by any major direct or indirect
injury to the lung. Common causes include:
• Aspiration
• Chest wall impact
• Near drowning
• Chemical inhalation injury
• Lung transplant
• Pneumonia
• Septic shock
• Trauma
https://medlineplus.gov/ency/article/000103.htm

50. Acute respiratory distress syndrome
• Depending on the amount of oxygen in the blood and
during breathing, the severity of ARDS is classified as:
– Mild
– Moderate
– Severe
• ARDS leads to a buildup of fluid in the air sacs (alveoli). This
fluid prevents enough oxygen from passing into the
bloodstream.
• The fluid buildup also makes the lungs heavy and stiff. This
decreases the lungs' ability to expand. The level of oxygen
in the blood can stay dangerously low, even if the person
receives oxygen from a breathing machine (ventilator)
through a breathing tube (endotracheal tube).
• ARDS often occurs along with the failure of other organ
systems, such as the liver or kidneys. Cigarette smoking and
heavy alcohol use may be risk factors for its development.
https://medlineplus.gov/ency/article/000103.htm

51. Acute respiratory distress syndrome
Outlook (Prognosis)
• About one third of people with ARDS die of the
disease. Those who live often get back most of
their normal lung function, but many people have
permanent (usually mild) lung damage.
• Many people who survive ARDS have memory
loss or other quality-of-life problems after they
recover. This is due to brain damage that
occurred when the lungs were not working
properly and the brain was not getting enough
oxygen.

52. P/F Ratio
ARDS Severity PaO2/FiO2* Mortality**
Mild 200 – 300 27%
Moderate 100 – 200 32%
Severe < 100 45%
https://lifeinthefastlane.com/ccc/acute-respiratory-distress-syndrome-ards-definitions/

53. Acute respiratory distress syndrome
Possible Complications
• VILI mechanisms are associated with a loss of
expiratory lung volume and stability
• Problems that may result from ARDS or its
treatment include:
– Failure of organ systems
– Ventilator Induced Lung Injury (VILI) due to injury
from the ventilator needed to treat the disease
– Pulmonary fibrosis (scarring of the lung)
– Ventilator-associated pneumonia
– PTSD
– PMV
– Death

54. Acute respiratory distress syndrome
• Alveolar instability and collapse result from inflammatory changes
as well as from loss of surfactant function.
• These changes plus edema formation from increased permeability
produce right-to-left shunting of blood and ventilation-perfusion
mismatching, both producing severe hypoxemia.
• Pulmonary hypertension occurs commonly in ARDS secondary to
vasoconstriction, thrombosis, perivascular edema and
inflammation, and eventual interstitial fibrosis.
• Overt right ventricular failure may develop if pulmonary
hypertension is severe.
• Although reported ARDS mortality rates today are less than
30%, recovery is often complicated by superimposed infections,
hyperoxic injury, ventilator-induced lung injury, and barotrauma.
Even with recovery, lung fibrosis may result in irreversible lung
dysfunction.
https://www.medscape.org/viewarticle/514525

55. Acute respiratory distress syndrome
• ARDS is sometimes classified as primary or
secondary.
• Primary ARDS describes lung injury from a
direct lung insult (eg, aspiration).
• Secondary ARDS describes lung injury as part
of a systemic process (ie, the lung is one of
many organs injured by a systemic
inflammatory response such as sepsis).
https://www.medscape.org/viewarticle/514525

56. BCV Opens the Lung Naturally to
Decrease Intensity of Illness
Applied when ARF recognized through peak of
illness to resolution offers the injured lungs
the least chance of further damage and the
best chance to recover as quickly as possible

57. BCV in
Combination Therapy
BCV CAN BE USED TO EFFECTIVELY ENHANCE
RESULTS IN COMBINATION
With Continuous or Intermittent Nebulization
With HFO2/Hi-VNI
With Mask NIPPV
With Heliox
With PPV in any mode
With HFOV
With ECMO
https://www.researchgate.net/Hayek-RTX-including-power-unit-and-cuirass-attached-to-an-intubated-patient-not_fig1_320639816

58. Pushmepullyou

59. BCV Case Studies
• 56 y.o. M with history of morbid obesity and chronic ETOH
abuse admitted with altered mental status, severe liver
disease and peritonitis with possible illeus. Chest X-ray
severe R lung atelectasis/infiltrates/effusions.
• Patient was on positive pressure ventilation with Assist
Control rate of 25, PEEP 15 and O2 at 100%. O2 saturation
was 80-82%. P/F low 60s.
• BCV was requested with goal of improving oxygenation.
BCV was set with largest size chest shell at CNEP of -20
with no initial adjustment to PPV settings
• After 14 hrs of BCV O2 had been weaned to 50% with O2
saturation of 98%. Serial ABGs obtained show patient
progressing throughout this time.

60. 14 hrs CNEP with PPV
P/F = 64 inc to 177
in 14 hrs
FiO2 PaO2
AADO2Settings

61. Critical Care 2012, 16:R37

62. NPV vs PPV in ARDS
• 6 patients monitored on NPV and PPV 2 hrs each
• 6 ml/kg and controlled for equal EELV for both
• NPV resulted in better oxygenation compared to
PPV with mean P/F of 345 mmHg vs 256 mmHg
• NPV airway pressures were considerably lower at
inspiration -1.5 cmH2O vs 34.5 cmH2O
• During NPV, intraabdominal pressures decreased
from 20.5 mmHg to 1 mmHg
• Conclusions:
NPV improved gas exchange in patients with
ARDS at lower transpulmonary, airway and
intraabdominal pressures

63. Combined Negative- and Positive-PressureVentilation for the Treatment of ARDS
Case Reports in Critical Care; Volume 2015, Article ID 714902,

64. Combined Negative- and Positive-
PressureVentilation for the Treatment
of ARDS
• 75 YO M with ARDS unresponsive to high PEEP
• External negative-pressure ventilation combined
with conventional pressure support using a
PEEP of about 8 cm H2O and a pressure support
of 4–12 cm H2O
• Alveolar infiltrates disappeared rapidly
• PaO2/FiO2 values surpassed 300mmHg after the
first application and 500mmHg after the second.
• Negative-pressure ventilation was used for 6–18
hours/day over five days.Combined Negative- and Positive-PressureVentilation for the Treatment of ARDS
Case Reports in Critical Care; Volume 2015, Article ID 714902,

65. What a Difference a Day and Negative
Lung Inflation Makes
Combined Negative- and Positive-Pressure Ventilation for the Treatment of ARDS

66. New Options
The possibility of effectively applying this and similar
concepts, not only in intubated but also in
nonintubated patients with ARDS, offers new options
that may genuinely differ from the present
therapeutic approaches. Therefore, these options
may have the potential to decrease the ongoing high
mortality rate associated with ARDS.
Combined Negative- and Positive-PressureVentilation for the Treatment of ARDS

68. Acute lung injury: how to stabilize a
broken lung
• The lung is designed to function optimally only
when fully inflated and thus the ideal situation
would be to cast the open lung and let it heal at
its biologically natural volume.
• Studies have shown that elevated airway
pressure with levels known to cause VILI is
relatively benign if the lung is not allowed to fall
significantly below FRC.
• Maintaining adequate FRC has also been shown
to be protective in the normal lung
• VILI mechanisms are associated with a loss of
expiratory lung volume and stability
Acute lung injury: how to stabilize a broken lung
Crit Care. 2018; 22: 136.

69. Acute lung injury: how to stabilize a
broken lung
• opening and stabilizing alveoli would prevent all
three mechanical mechanisms of VILI
• progression to ARDS is often silent with normal
blood gases in the presence of ARDS with unstable
alveoli leading clinicians to believe the lung is “fine”
• by the time this level of lung pathology is present,
there is already considerable tissue and surfactant
damage resulting in a significant loss of lung volume
predisposing the lung to VILI
• “Never give the lung a chance to collapse” and by
doing so eliminate most VILI pathophysiology
Acute lung injury: how to stabilize a broken lung
Crit Care. 2018; 22: 136.

70. Extra-thoracic Lung Casting
• Open lung with BCV
• Use of Continuous Negative or highly negative Control
Mode settings to set a guard against loss of FRC
• Use of Extrathoracic Lung Casting (ELC) initiated at
early signs of respiratory distress to prevent lung
contracture and prevent illness escalation that would
be resultant from loss of FRC/atelectasis
• ELC can be maintained through mask to intubation and
PPV potentiall shortening duration and lessening
intensity of illness and PPV settings
• Goal: Earlier extubation and more rapid recovery for
larger number of survivors

71. The effectiveness of continuous negative
abdominal pressure management in a patient
with severe obesity experiencing respiratory failure
The effectiveness of continuous negative abdominal pressure management
in a patient with severe obesity experiencing respiratory failure
J Jpn Soc Intensive Care Med 2018;25:26-30

72. The effectiveness of continuous negative
abdominal pressure management in a patient
with severe obesity experiencing respiratory
failure
The effectiveness of continuous negative abdominal pressure management in a patient with severe obesity experiencing respiratory
failure
J Jpn Soc Intensive Care Med 2018;25:26-30

73. Continuous Negative Abdominal Pressure Recruits
Lungs at Lower Distending Pressures
• Ventilator-induced lung injury in acute respiratory distress
syndrome (ARDS) occurs mostly in ventilated, nondependent lung
regions, termed the baby lung
• Recruitment of dependent atelectasis involves transient elevations
of airway pressure to increase the size of the baby lung and reduce
its susceptibility to injury from inspiratory stretch. Clinical studies of
these techniques, however, have resulted in only marginal benefit
possibly because increased airway pressure first overinflates (and
potentially injures) already aerated regions before recruiting
atelectatic lung.
• Abdominal pressure is a key factor that increases the propensity to
dependent atelectasis. Negative pressure applied outside the
abdomen can lower the intra-abdominal pressure in patients and
could potentially decrease dorsal atelectasis by caudal shift of the
diaphragm.
American Journal of Respiratory and Critical Care Medicine Volume 197 Number 4 | February 15 2018

74. Continuous Negative Abdominal
Pressure Recruits
Lungs at Lower Distending Pressures
American Journal of Respiratory and Critical Care Medicine Volume 197 Number 4 | February 15 2018

75. Continuous Negative Abdominal
Pressure Recruits
Lungs at Lower Distending Pressures
American Journal of Respiratory and Critical Care Medicine Volume 197 Number 4 | February 15 2018

76. Continuous negative abdominal pressure:
mechanism of action and comparison
with prone position
We recently reported that continuous negative
abdominal pressure (CNAP) could recruit
dorsal atelectasis in experimental lung injury
and that oxygenation improved at different
transpulmonary pressure values compared
with increases in airway pressure
Continuous negative abdominal pressure: mechanism of action and comparison with prone position.
J Appl Physiol (1985). 2018 Jul 1;125(1):107-116.

77. Continuous negative abdominal pressure:
mechanism of action and comparison
with prone position
• The mechanism of recruitment with CNAP is
uncertain, and its impact compared with a
commonly proposed alternative approach to
recruitment, prone positioning, is not known.
• We hypothesized that CNAP recruits lung by
decreasing the vertical pleural pressure (P )
gradient (i.e., difference between dependent
and nondependent P ), thought to be one
mechanism of action of prone positioning.
Continuous negative abdominal pressure: mechanism of action and comparison with prone position.
J Appl Physiol (1985). 2018 Jul 1;125(1):107-116.

78. Continuous negative abdominal pressure:
mechanism of action and comparison
with prone position
• CNAP lowered the P in dependent but not in
nondependent lung, and therefore, in contrast
to PEEP, it narrowed the vertical P gradient.
CNAP increased respiratory system
compliance and oxygenation and appeared to
selectively displace the posterior diaphragm
caudad (computerized tomography images).
Continuous negative abdominal pressure: mechanism of action and comparison with prone position.
J Appl Physiol (1985). 2018 Jul 1;125(1):107-116.

79. Continuous negative abdominal pressure:
mechanism of action and comparison
with prone position
• Compared with prone position without CNAP, CNAP in the
supine position was associated with higher arterial partial
pressure of oxygen and compliance, as well as greater
homogeneity of ventilation.
• The mechanism of action of CNAP appears to be via
selective narrowing of the vertical gradient of P . CNAP
appears to offer physiological advantages over prone
positioning.
• NEW & NOTEWORTHY Continuous negative abdominal
pressure reduces the vertical gradient in (dependent vs.
nondependent) pleural pressure and increases oxygenation
and lung compliance; it is more effective than prone
positioning at comparable levels of positive end-expiratory
pressure
Continuous negative abdominal pressure: mechanism of action and comparison with prone position.
J Appl Physiol (1985). 2018 Jul 1;125(1):107-116.

80. Lung recruitment: The combined effect
of pressures North and South of the
Diaphragm
• PEEP alone did not result in lung recruitment,
whereas PEEP+CNAP did open a significant
volume of lung, especially in the
diaphragmatic lung regions
• They concluded that CNAP might be a
potential adjunct to PEEP in the recruitment
of diaphragmatic atelectasis
Lung recruitment: the combined effect of pressures "North" and "South" of the diaphragm
Crit Care Med. 2012 Jun;40(6)

81. BCV for ARDS
• Few improvements in mortality since
ARDSNET
• Oxygenation and compliance benefit from
successful restoratin/maintenance of FRC
• BCV works well with HFO2, NIPPV, and PPV for
better result in ARDS
• BCV improves P/F
• BCV increases FRC

82. Questions
82 Gary.Mefford@hayekmedical.com
hayekmedical.com