Effects of preserved spontaneous breathing activity during mechanical ventilation in experimental intra-abdominal hypertension

Dietrich Henzler

Nadine Hochhausen

Ralf Bensberg

Alexander Schachtrupp

Sonja Biechele

Rolf Rossaint

Ralf Kuhlen

Electronic Supplemental Material

Table 1. Control- group without intra-abdominal hypertension: Respiratory mechanics (cumulative data during 24h of ventilation)

Control- group / p-value
BIPAPPC / BIPAPSB
PIP
(mmHg) / 22±4 / 18±2* / <0.0001
RR_tot
(min-1) / 24±3 / 29±3* / 0.001
Ve_tot
(l/min) / 8.4±0.9 / 8.6±1.2 / 0.449
Cdyn
(ml/cmH2O) / 26.2±6.0 / 36.7±9.1* / <0,0001
WOB_tot
(cmH2O) / 42.9±9.6 / 36.5±6.2* / 0.002

BIPAPPC = biphasic positive airway pressure without spontaneous breathing; BIPAPSB = with spontaneous breathing; IAP = intraabdominal pressure; PIP = peak inspiratory pressure; RR_tot = total respiratory rate; Ve_tot = total minute ventilation; Cdyn = dynamic compliance; WOB_tot = total work of breathing

*indicates difference between groups

Table 2:Control group without intra-abdominal hypertension: Gas exchange (cumulative data during 24h of ventilation)

Control- group / p-value
BIPAPPC / BIPAPSB
paO2
(mmHg) / 140±26 / 125±33 / 0.079
paCO2
(mmHg) / 35±5 / 43±11* / 0.001
DO2
(ml/min) / 420±94 / 530±109* / <0.0001
Qva/Qt
(mmHg) / 3.8±4.3 / 5.8±7.2 / 0.129

BIPAPPC = biphasic positive airway pressure without spontaneous breathing; BIPAPSB = with spontaneous breathing; paO2 = arterial partial oxygen pressure, paCO2 = arterial partial carbon dioxide pressure, DO2 = oxygen delivery, Qva/Qt = venous admixture

*indicates difference between groups

Table 3. Control group without intra-abdominal hypertension: Hemodynamics (cumulative data during 24h of ventilation)

Control- group / p-value
BIPAPPC / BIPAPSB
HR
(min-1) / 96±10 / 98±21 / 0.575
MAP
(mmHg) / 107±15 / 113±17 / 0.108
MPAP
(mmHg) / 19±5 / 27±31 / 0.137
CVP
(mmHg) / 6±3 / 9±2* / <0.001
PAOP
(mmHg) / 7±3 / 10±3* / <0.001
CO
(l/min) / 4.4±1.1 / 5.2±1.1* / 0.004
SV
(ml) / 45.6±11.1 / 53.8±11.5* / 0.005
PVR
(dyn*sec/Cm5) / 234.3±58.3 / 187.2±96.2* / 0.019

BIPAPPC = biphasic positive airway pressure without spontaneous breathing; BIPAPSB = with spontaneous breathing; IAP = intraabdominal pressure; HR = heart rate; MAP = mean arterial pressure; MPAP = mean pulmonary artery pressure; CVP= central venous pressure; PAOP =pulmonary artery occlusion pressure; CO = cardiac output; SV = stroke volume; PVR = pulmonary vascular resistance. *indicates difference between groups

Figure 1 Cardiac output during 24 hours of BIPAP ventilation without (BIPAPPC) and with spontaneous breathing (BIPAPSB)in control animals without intra-abdominal hypertension

Figure 2 Cardiac output during two 9 h phases of intra-abdominal hypertension duringBIPAP ventilation without (BIPAPPC) and with spontaneous breathing (BIPAPSB; data from 3 animals in second IAP phase only)


Figure 3 Work of breathing during 24 hours ofBIPAP ventilation without (BIPAPPC) and with spontaneous breathing (BIPAPSB) in control animals without intra-abdominal hypertension.


Figure 4 Work of breathing during two 9 h phases of intra-abdominal hypertension duringBIPAP ventilation without (BIPAPPC) and with spontaneous breathing (BIPAPSB; data from 3 animals in second IAP phase only)

Figure 5Histology of lower lobe lung of ventilation with biphasic positive airway pressure with unsupported spontaneous breathing (BIPAPSB). HE staining, magnification 100x. a) after 24 h (control) b) after two phases of 9 h with intra-abdominal hypertension and 3h of pressure relief. Note the loss of airspace, alveolar edema and neutrophils infiltration in b).

Figure 5Histology of upper lobe lung after two phases of 9 h with intra-abdominal hypertension. HE staining, magnification 40x. a) ventilation with biphasic positive airway pressure with unsupported spontaneous breathing (BIPAPSB) b) ventilation without spontaneous breathing (BIPAPPC). Note areas of loss of airspace and neutrophil infiltration in a).