Effects Of Continuous Positive Pressure Ventilation Research Articles

Continuous Negative Extrathoracic Pressure Ventilation, Lung Water Volume, and Central Blood Volume: Studies in Dogs with Pulmonary Edema Induced by Oleic Acid

The effect of continuous positive-pressure ventilation (CPPV) on extravascular lung water volume has been investigated, but there is only one report which studied the effect of continuous negative extrathoracic pressure ventilation (CNETPV). The effect of CNETPV on central blood volume (CBV) has not been studied. Changes in intrathoracic pressure by CNETPV may alter lung water volume and CBV. In this study the effects of CNETPV on lung water volume and CBV were compared with those of intermittent positive-pressure ventilation (IPPV) and CPPV in dogs with pulmonary edema induced by oleic acid. Nine mongrel dogs were anesthetized and given oleic acid at 0.06 ml/kg intravenously to induce pulmonary edema; CNETPV was applied with a cuirass and a negative thoracic pressure ventilator (Kimura OKT-100) for 1 h. Extravascular lung water volume (as extravascular thermal volume [EVTV]) and CBV were estimated with the double-indicator dilution method using thermal-sodium; PEEP and continuous negative extrathoracic pressure were matched to produce the same increments in FRC. The EVTV increased during CNETPV but did not change during CPPV. The CBV decreased during CPPV but did not change during CNETPV. An increase of transmural pulmonary microvascular pressure was thought to be one of the reasons for the increase in EVTV with CNETPV.

Effect of continuous positive-pressure ventilation on oxygenation after pulmonary microemboli in dogs.

We infused starch microemboli (63 to 74-mu diameter) into the external jugular vein of 28 dogs, to observe the effects of continuous positive-pressure ventilation (CPPV) on gas exchange and hemodynamics during hypoxemia (PaO2 53 +/- 3 torr). CPPV at both 10 and 15 cm H2O end-tidal pressure improved PaO2. CPPV 15 returned PaO2 and pulmonary shunt to control values but reduced cardiac output, O2 transport, and O2 consumption. In spite of these changes suggesting inadequate tissue oxygenation with CPPV 15, mixed venous oxygenation was not reduced. We conclude that: (a) hypoxemia after microemboli infusion is improved by CPPV and therefore likely caused by ventilation/perfusion abnormalities; (b) the improvement in PaO2 produced by CPPV after microemboli is not beneficial if CPPV reduces perfusion and O2 transport; and (c) mixed venous oxygenation does not appear to be an adequate measure of oxygen transport to tissues when CPPV is applied in this high pulmonary vascular resistance setting.

A case of drowning

AnaesthesiaVolume 31, Issue 9 p. 1296-1297 Free Access A case of drowning Jerome H. Modell, Jerome H. Modell Department of Anesthesiology, University of Florida, Gainesville, FloridaSearch for more papers by this author Jerome H. Modell, Jerome H. Modell Department of Anesthesiology, University of Florida, Gainesville, FloridaSearch for more papers by this author First published: November 1976 https://doi.org/10.1111/j.1365-2044.1976.tb11999.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References 1 Calderwood, H.W., Modell, J.H. & Ruiz, B.C. (1975) The ineffectiveness of steroid therapy for treatment of fresh-water near-drowning. Anesthesiology, 43, 642. 2 Modell, J.H., Graves, S.A & Ketover, A. (1976) Clinical course of 91 consecu tive near-drowning victims, Abstract, Critical Cure Medicine, 4, 127. 3 Chapman, R.L., Downs, J.B., Modell, J.H. & Hood, C.I. (1974) The ineffectiveness of steroid therapy in treating aspiration of hydrochloric acid. Archives of Surgery, 108, 858. 4 Chapman, R.L., Modell, J.H., Ruiz, B.C., Calderwood, H.W., Hood, C.I. & Graves, S.A. (1974) Effect of continuous positive-pressure ventilation and steroids on aspiration of hydrochloric acid (pH 1.8) in dogs. Anesthesio arid Analgesia, Current Researches, 53, 556. 5 Downs, J.B. Chapman, R.L., Modell, J.H. & Hood, C.I. (1974) An evaluation of steroid therapy in aspiration pneumonitis. Anesthesiology, 40, 129. 6 Modell, J.H., Moya, F., Newby, E.J., Ruiz, B.C. & Showers, A.V. (1967) The effects of fluid volume in seawater drowning. Annals of Internal Medicine, 67, 68. 7 Modell, J.H. & Moya, F. (1966) Effects of volume of aspirated fluid during chlorinated fresh water drowning. Anesthesiology, 27, 662. 8 Modell, J.H. & Davis, J.H. (1969) Electrolyte changes in human drowning victims. Anesthesiology, 30, 414. 9 Swann, H.G. & Spafford, N.R. (1951) Body salt and water changes during fresh water and sea water drowning. Texas Reports on Biology arid Medicine, 9, 356. 10 Rutz, B.C., Calderwood, H.W., Modell, J.H. & Brogdon, J.E. (1973) Effect of ventilatory patterns on arterial oxygenation after near-drowning with fresh water. 11 Modell, J.H., Calderwood, H.W., Rutz, B.C., Downs, J.B. & Chapman, R.L. (1974) Effects of ventilatory patterns on arterial oxygenation after near-drowning in sea water. Anesthesiology, 40, 376. Volume31, Issue9November 1976Pages 1296-1297 ReferencesRelatedInformation

Effects of continuous positive-pressure ventilation in experimental pulmonary edema.

We compared the effects of continuous positive-pressure ventilation (CPPV), using 10 cmH2O positive end-expiratory pressure (PEEP), with intermittent positive-pressure ventilation (IPPV), on pulmonary extravascular water volume (PEWV) and lung function in dogs with pulmonary edema caused by elevated left atrial pressure and decreased colloid osmotic pressure. The PEWV was measured by gravimetric and double-isotope indicator dilution methods. Animals with high (22-33 mmHg), moderately elevated (12-20 mmHg), and normal (3-11 mmHg) left atrial pressures (Pla) were studied. The PEWV by both methods was significantly increased in the high and moderate Pla groups, the former greater than the latter (P less than 0.05). There was no difference in the PEWV between animals receiving CPPV and those receiving IPPV in both the high and moderately elevated Pla groups. However, in animals with high Pla, the Pao2 was significantly better maintained and the inflation pressure required to deliver a tidal volume of 12 ml/kg was significantly less with the use of CPPV than with IPPV. We conclude that in pulmonary edema associated with high Pla, PEEP does not reduce PEWV but does improve pulmonary function.

Effect of Continuous Positive-Pressure Ventilation and Steroids on Aspiration of Hydrochloric Acid (pH 1.8) in Dogs

Forty mongrel dogs were studied to determine whether pharmacologic doses of methylpredniso-lone sodium succinate alone, or in combination with continuous positive-pressure ventilation (CPPV), would alter the course of pneumonitis after aspiration of hydrochloric acid (HCl) of pH 1.8. The dogs were anesthetized and divided into four equal groups. One group aspirated 2 ml./kg. of HCl and was not treated. A second group was treated 21 minutes after aspiration with 30 mg./kg. of methylprednisolone intravenously (I.V.) every 8 hours for 72 hours. A third group received mechanical ventilation (15 ml./kg. VT) with 10 cm. of water PEEP (CPPV) until 300 minutes after aspiration. The last group received CPPV plus steroid therapy. Half of the animals in each group were sacrificed after 300 minutes for lung examination. The remaining animals were sacrificed after 2 weeks. The Pao2 fell in all animals after aspiration of HCl; however, Pao2 improved with time, 95 percent of the animals surviving the experiment. No beneficial effect of methylprednisolone was demonstrated in improving arterial oxygenation, pathologic changes in lungs, or survival rate, but CPPV dramatically improved the gross appearance of the lungs compared to those of dogs allowed to breathe spontaneously following aspiration. Both cardiac output and mean arterial blood pressure decreased following aspiration and still further decreased following the institution of CPPV. The authors recommend that when CPPV is indicated in the treatment of aspiration pneumonitis, attention be given to maintenance of an adequate blood volume and cardiac output.

Effects of continuous positive-pressure ventilation on gas exchange in acute pulmonary edema.

Effects of continuous positive-pressure ventilation on gas exchange in acute pulmonary edema.