The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts

THE UTILIZATIONOF THE VOLUMETRIC DIFFUSIVE RESPIRATOR TO IMPROVE OXYGENATION AND CONTROL INTRACEREBRALPRESSURE.

Kenneth Miller,RRT,MEd;William Dougherty, MD; Steven Pyne, RRT,BS; Kristin Sedler, RRT; Ronnie Wihlem,RN.Lehigh Valley Hospital. Allentown, PA 18105

Introduction: Themanagement of the patient who presents with a significant intracerebral injuryand who later develops pulmonary decompensation can be very challenging. Attemptsto promote mucokinesis via pulmonary drainage or external percussion can causesignificant increases in the intracerebral pressure (ICP). Pulmonary decompensationleads to poor oxygenation and inadequate ventilation that can contribute toan increase in ICP. Ventilator management, which is directed at elevating themean airway pressure, can impair cerebral venous blood and play a role in risingthe ICP1 . The challenge that the clinician faces is how to promotegood pulmonary hygiene and oxygenation without negatively influencing the ICP.We present a case study in which these clinical endpoints were achieved by utilizingthe Volumetric Diffusive Respirator (VDR).

Case Summary: Aneighteen year old female who was involved in a MVA was admittedto the Trauma-Neuro unit. On admission the diagnosis of several small punctatehemorrhages was made. The patient responded to noxious simulate but did notfollow simple commands, a Glascow Score of nine was assigned. Intubation andplacement of an intraventricular drain was inserted for intra-cerebral pressurecontrol. PIO2/FIO2 (P/F) ratio was 600 and chest x-rayunremarkable upon admission. Pedestrian ventilatory parameters were set to maintaina PaC02 around 30 torr and FIO2 of 30% to maintain a PaO2around 100 torr or P/F ratio 330. Lung compliance was 50cc/cm/H20.Three days post admission chest x-ray revealed small bilateral infiltrates andthe P/F ratio dropped to 200. There was a noticeable increase in ICP and thepatient was placed in a chemically induced coma along with aggressive diuresis.Twenty-four hours later bilateral infiltrates were noted on chest x-ray andthe P/F ratio dropped to 81 on FIO2 100%. Lung compliance deteriorated to 30cc/cm/H20.Secretions were noted to be mucopurulent and attempts to facilitate mucus removalwith manual hand-ventilation was terminated secondary to increased ICP. Effortsat positioning to enhance pulmonary drainage or perform external percussionwere terminated secondary to significant elevations in the ICP. The decisionwas made to change the ventilator strategy from conventional ventilation andutilize the VDR. Initial parameters were peak inspiratory pressure of 42cm/H20,PEEP 14cm/H20, rate of 15, 1:1 inspiratory/expiratory ratio and FI02100%. Upon initiation of the VDR secretion removal was enhanced without increasein ICP. Within sixteen hours after initiation of the VDR the P/F ratio increasedto 280 on 45% FIO2. Within thirty-six hours there was a visible decreasein pulmonary infiltrates via chest x-ray. ICP was reduced to an acceptable level.The FIO2 was reduced lower with no reduced in the P/F ratio.

Conclusion: Managementof the patient with intracerebral injury and respiratory decompensation is complexand problematic. The VDR provides solutions to some of the problems associatedwith this type of clinical picture. By providing internal pulmonary percussionvia its oscillatory mechanics and improving oxygenation with its diffusive functionpulmonary endpoints can be achieved without significant negative effect on theICP. Davis and associates2 demonstrated this previously and our casesummary supports their findings.

1. Schedl R. VentilatorDependent Modification of the Intercranial Pressure Curve. J. Clinical Monitor1987;3:326.

2. Davis K, Hurst J,Branson R. High FrequencyPercussive Ventilation. Problems in Respiratory Care; 1989; 39-47.

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