Patients who undergo laparoscopic surgery often experience increased intracranial pressure (ICP). In laparoscopic colectomy surgery, the duration always exceeds 2h with more liability to changes in arterial blood gases, hemodynamics, also the patient is in Trendelenburg position about 30° head down, Trendelenburg position is believed to create changes in hemodynamics, respiratory mechanics, metabolic response, and ICP as it affects vital organs especially if steep positioning. Various modes of mechanical ventilation have been experimented to achieve good intraoperative oxygenation which may cause changes in arterial blood gas values and hemodynamic parameters that might lead to changes in the ICP. In this study we will measure ONSD, basal, intraoperative, and in the PACU to evaluate the effect of different ventilation modes (both VCV mode and PCV-VG mode) on intracranial pressure.
The aim of the current study is to compare the effect of volume control ventilation (VCV) versus pressure control ventilation-volume guaranteed (PCV-VG) as modes of mechanical ventilation on ICP by US guided ONSD measurement during laparoscopic colectomy,
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
78
Volume control ventilation mode
Pressure control ventilation-volume guaranteed mode
Mansoura University
Al Mansurah, DK, Egypt
Changes in ONSD O(optic) N(nerve) S(sheath) D(diameter)
ONSD is the acronym of O(optic) N(nerve) S(sheath) D(diameter), that ONSD is a non invasive method for measurement of intracranial pressure The optimal cutoff value has not been established, they vary between 4.85 and 5.9 mm and \>5.9 mm is a sure sign of increased intracranial tension
Time frame: Changes from baseline, till 30 minutes after recovery from anaesthesia
Heart rate
is allowed to swing within 20% of the basal value
Time frame: Changes from baseline, till 30 minutes after recovery from anaesthesia
Mean arterial blood pressure
is allowed to swing within 20% of the basal value
Time frame: Changes from baseline, till 30 minutes after recovery from anaesthesia
Peak airway pressure
Peak airway pressure values should not exceed 30 cm H2O. Values greater than 40 cm H2O may be harmful to the normal lung. Peak pressure applies when there is airflow in the circuit, i.e.the maximum pressure during inspiration . What determines the peak pressure is the airway resistance in the lungs. So if there is a problem with the airways the peak pressure will rise.
Time frame: intra-operative changes from time of induction of anesthesia and intubation (post induction), till the end of surgery (before extubation).
Plateau airway pressure
Plateau pressure is the pressure applied to small airways and alveoli during positive-pressure mechanical ventilation.when there is no air flow in the circuit. That is when inspiration is complete. This pressure is determined by the lung compliance. So it follows that if there is a problem with the compliance the plateau pressure will rise. Plateau pressure is measured during an inspiratory pause on the mechanical ventilator. Pplat is never bigger than PIP and is typically \<10 cm H2O lower than PIP when airway resistance is not elevated.
Time frame: intra-operative changes from time of induction of anesthesia and intubation (post induction), till the end of surgery (before extubation).
mean airway pressure
mean airway pressure typically refers to the mean pressure applied during positive-pressure mechanical ventilation. Mean airway pressure correlates with alveolar ventilation, arterial oxygenation, hemodynamic performance, and barotrauma
Time frame: intra-operative changes from time of induction of anesthesia and intubation (post induction), till the end of surgery (before extubation).
Dynamic Lung compliance
dynamic lung compliance Cdyn = VT / (PIP - PEEP)…..change in volume/change in pressure, where airflow resistance becomes a factor. which ranges physiologically in adults between 50 - 80 ml/cm H2O while for intubated, mechanically ventilated adults is about 30 to 40 ml/cm H2O
Time frame: intra-operative changes from time of induction of anesthesia and intubation (post induction), till the end of surgery (before extubation).
Static Lung compliance
static compliance and dynamic compliance static lung compliance....Cstat = VT/ ( Pplat - PEEP) ….change in volume/change in pressure when there is no air flow..... The physiological Cstat for adult is 70 - 100 while for intubated, mechanically ventilated adults is about 50 to 60 ml/cm H2O
Time frame: intra-operative changes from (post induction) just after induction of anesthesia and intubation, till the end of surgery (before extubation).
pH
PH ranges normally between 7.35 - 7.45 when \>7.45 it is alkalosis when \<7.35 it is acidosis
Time frame: Changes from baseline, till 30 min after recovery from anesthesia.
PaCO2 (carbon dioxide tension)
PaCo2 which ranges normally between 35 -45 mmHg it increase above 45 with causes of hypercapnia as hypoventilation and insufflation with Co2 and decrease below 35 with hypotension, hypo-perfusion and excessive hyperventilation Normal PaCO2-EtCO2 difference is 2-5 mmHg
Time frame: Changes from baseline, till 30 min after recovery from anesthesia.
Headache
the severity of headache will be recorded using visual analogue score (where 0 = no pain and 10 = worst pain imaginable), mild headache pain will be defined by scores 1-4, moderate; by scores 5-7, and severe; by scores 8-10.
Time frame: for 24 hour after surgery
Postoperative nausea and vomiting
Nausea will be explained to all patients, where ( 0 = no symptoms, 1 = mild symptoms, 2 = moderate symptoms, 3 = severe symptoms ) and also the incidence of vomiting will be recorded by asking a questionnaire to all patients; is vomiting present or absent.
Time frame: for 24 hour after surgery
PaO2 (partial pressure of arterial oxygen)
PaO2 should= FiO2 x 500 (e.g. 0.21 x 500 = 105 mmHg)
Time frame: Changes from baseline, till 30 min after recovery from anesthesia
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