Intrathoracic pressure regulation (IPR) therapy, delivered by impedance threshold devices (ITDs) or intrathoracic pressure regulators (ITPRs), increases venous return, preload, cardiac output, blood pressure, and cerebral perfusion pressure by intermittently creating negative intrathoracic pressure, which improves circulation in hypotensive animals and humans. By increasing systemic pressure and cerebral perfusion as well as promoting venous return, IPR therapy potentially improves cerebral oxygenation. The lower intrathoracic pressures may also reduce pulmonary artery pressure, although there is currently little evidence one way or the other. Use of an ITPR can counteract the multifactorial intraoperative hypotension common during surgeries under general anesthesia, and reduce the need for other measures to treat such hypotension; however, they might simultaneously promote pulmonary complications. The investigators will therefore assess whether the use of intrathoracic pressure regulation in adults having shoulder surgery under general anesthesia in the sitting position reduces vasoactive medication requirements compared with routine clinical practice. Simultaneously, the investigators will assess the effect of intrathoracic pressure regulation on pulmonary circulation, cerebral oxygenation, and postoperative atelectasis.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
CirQPOD is connected between the wye piece on ventilator/anesthesia machine tubing and the patient's airway and generates negative intrathoracic pressure during the expiratory phase of ventilation which has been shown to improve blood flow.
Standard airway management during surgery (PEEP of +5 cmH2O)
Outcomes Research, Anesthesia Institute, Cleveland Clinic
Cleveland, Ohio, United States
Phenylephrine use
Amount of phenylephrine required to maintain MAP of 80±5 mmHg
Time frame: from device placement to start of wound closure, a period of up to four hours
Pulmonary artery pressure
pressure in the pulmonary artery as measured by transesophageal echocardiography (TEE)
Time frame: at least two minutes after IPR level of -10 cmH2O has been set
Atelectasis
presence and amount of atelectasis as determined by chest computerized tomography (CT)
Time frame: first day post-op
PaO2
post-operative partial arterial oxygen pressure measured by arterial blood gas (ABG)
Time frame: at least 20 minutes, but not more than 2 hours, after patient is free of oxygen supplementation
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