Patient Positioning and Monitoring for Laparoscopy

Patients must be positioned (see Chapter 28 ) with great care to prevent nerve injuries; padding should protect from nerve compression, and shoulder braces, if needed, should be placed overlying the coracoid process. Patient tilt should be reduced as much as possible and should not exceed 15 to 20 degrees. Tilting must be slow and progressive to avoid sudden hemodynamic and respiratory changes. The position of the endotracheal tube must be checked after any change in patient position. Induction and release of the pneumoperitoneum must be smooth and progressive. Mask ventilation before intubation can inflate the stomach with gas, which must be aspirated before trocar placement to avoid gastric perforation, particularly for supramesocolic laparoscopy. The bladder should be emptied before pelvic laparoscopy or prolonged procedures.

During laparoscopy, arterial blood pressure, heart rate, electrocardiogram, capnometry, and pulse oximetry must be continuously monitored. Although this level of monitoring is valuable for detection of cardiac arrhythmias, gas embolism, CO₂ subcutaneous emphysema, and pneumothorax, it provides only indirect evidence of the hemodynamic changes induced by the pneumoperitoneum. Although more invasive hemodynamic monitoring may be necessary in patients with cardiac diseases, increased intrathoracic pressure complicates the interpretation of measured central venous and pulmonary artery pressures. Transesophageal echocardiography may be more helpful in patients with severe cardiac disease (see Table 57-2 ), PETCO₂ and SpO₂ reliably reflect PaCO₂ and arterial oxygen saturation (SaO₂ ). However, the Δa-ETCO₂ may vary from patient to patient and during the course of laparoscopy in the same patient. PETCO₂ must be monitored carefully to avoid hypercapnia and to detect gas embolism. Because Δa-ETCO₂ may increase more in patients with cardiac and pulmonary diseases, cannulation of a radial artery may be helpful to allow direct measurement of PaCO₂ from an arterial blood sample.