The Hemodynamic and Respiratory Effects of “Spacemaker” Facilitated Thoracoscopy vs. Conventional Facilitated Thoracoscopy in a Porcine Model
Pieter W. Lozekoot1, Paul B. Kwant1, Paul F. Gründeman2, Jos G. Maessen1.
1Maastricht University Medical Center, Maastricht, Netherlands, 2University Medical Center Utrecht, Utrecht, Netherlands.
OBJECTIVE: Minimally invasive cardiothoracic surgery, requires carbondioxide (CO2) -insufflation and/or single lung ventilation (SLV) to gain surgical exposure. These techniques may coincide with a firm drop in hemodynamic and respiratory parameters. We invented an inflatable lung retractor called “Spacemaker”, which should facilitate thoracoscopy without the homeostatic sequellae associated with conventional techniques.
We present an experimental study evaluating the physiological effects of this novel tool in comparison with the effects of conventional techniques.
METHODS: Fourteen anesthetized pigs (90-100kg) were allocated to either “Spacemaker” facilitated left-sided thoracoscopy (n=7) or a sequence of thoracoscopy (control n=7) with two lung ventilation (TLV) or SLV with or without CO2-insufflation up to 12 mmHg. “Spacemaker” introduction was performed trough a soft-tissue port in the fifth intercostal space, gently pushing the lung dorsally, creating similar surgical exposure as observed with conventional techniques. Control group animals received a 10mm trocar in the fifth intercostal space for CO2-insufflation, while SLV was achieved through a bronchial blocker in the left main bronchus. During experiments hemodynamic and ventilatory functions were monitored.
RESULTS: SLV did not significantly alter stroke volume (SV), mean arterial pressure (MAP), paO2 or paCO2. Additional intrathoracic CO2-insufflationdiminished SV. During TLV, similar effects were observed, but did not reach significance at 4mmHg CO2-insufflation. “Spacemaker” positioning initially led to a decrease in SV which almost recovered at follow up. These observations did only translate into a decrease in MAP’s during CO2-insufflation both in SLV as also in TLV, but not in the “Spacemaker” group. During insufflations of various pressures of CO2, paO2 decreases were observed in both SLV as TLV, but not in the “Spacemaker” group. The “Spacemaker” group showed a decrease of paCO2 after 2 and 3 hours.
CONCLUSIONS: “Spacemaker” facilitated thoracoscopy, obviating SLV and/or CO2-insufflation, showed an equal decrease in hemodynamic function as observed with current clinical practice (SLV + CO2 8 mmHg). Optimization of the model, is expected to further preserve the hemodynamic homeostasis and possibly offer an alternative to conventional techniques.
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