الفهرس 
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Abstract
Pulmonary hypertension is a significant predictor of major
perioperative cardiovascular complications in patients undergoing
cardiac surgery. The PH is commonly considered to exist when the
mean pulmonary artery pressure exceeds 25 mm Hg at rest and 30 mm
Hg during exercise. PH is a frequent and serious complication of
mitral valve disease, resulting from elevated left atrial pressure.
Management of these patients is challenging due to their tenuous
hemodynamic status. Recent advances in the understanding of the
patho-physiology, risk factors, monitoring, and treatment of the
disease provide an opportunity to reduce the morbidity and mortality
associated with PH in the peri-operative period.
Weaning from cardiopulmonary bypass can be difficult in
cardiac surgery patient due to various reasons such as intrinsic
mycordial dysfunction, inadequate myocardial protection, both
ischemia-reperfusion of pulmonary vascular endothelium, activation
of inflammatory and vasoconstrictor cascades or high pulmonary
vascular resistance. Current management is aimed at minimizing risk
factors, optimizing hemodynamics (right ventricular preload,
afterload, and contractility), and aggressively treating complications.
Strategies to reduce pulmonary vascular tone aim to enrich vascular smooth muscle cyclic adenosine monophosphate (cAMP) levels by Badrenoreceptors
or with phosphodiesterase type III inhibitors.
Alternatively, increasing cyclic guanine monophosphate (c GMP) with
nitroso vasodilators (sodium nitroprusside, nitroglycerin, inhaled nitric
oxide [NO]) also reduces pulmonary vascular tone.
The aim of this work was to compare the effect of dobutamine
and nitroglycerin versus milrinone in perioperative management of
pulmonary hypertension associated with mitral valve disease in
patients undergoing mitral valve replacement.
We studied 40 patients scheduled for MVR surgery.All the
patients had a PAP > 50 mmHg to be enrolled in the study. The
patients were randomly divided by closed envelope method into two
equal groups according to the drugs given during weaning from CPB.
group І: Twenty patients received dobutamine 5-20 μg / kg/
min and nitroglycerin 0.5-5 μg / kg/ min. group П: Twenty patients received milrione, loading dose of 50
μg/kg over 10 min followed by a maintenance dose of 0.25- 0.75
μg/kg /min.
General anesthesia was started by inserting an 18 Gauge
peripheral intravenous cannula and the patients were premedicated
with midazolam 2-4 mg I.V. A radial arterial line was inserted under
local anesthesia. The following monitors were applied: ECG leads II
and V, pulse oximetry and invasive arterial blood pressure. During anesthetic induction each patient received 250-500 mL
of Ringer’s lactate to maintain a peripheral venous access and infusion
of drugs. Anethesia was induced with fentanyl (10-15 μg/kg),
thiopentone (3-5 mg/kg) and pancuronium (0.08 mg/kg).Ventilation
was maintained via face mask till the patient was fully relaxed and
then a cuffed endotracheal tube with suitable size was introduced and
fixed. Capnography was applied.
An 8.5-Fr introducer was inserted into the right jugular vein and
a 7.5-Fr 4-lumen- pulmonary artery catheter, (Baxter Critical Care, California, USA) (Arrow Swan Ganz catheter) was inserted and
connected to the hemodynamic monitor (Drager monitor). The
catheter was advanced into the PA guided by the pressure curves.
Correct positioning was confirmed postoperatively by chest
radiograph. All transducers were positioned at the midaxillary line and
zeroed to atmospheric pressure.
Measurements were included: Demographic data: age, sex,
weight, height and BMI, Echocardiographic data.
For Hemodynamic measurements, heart rate (HR), systolic,
diastolic and mean arterial pressures (SBP, DBP and MAP) along with
central venous pressures (CVP). Using the Swan Ganz catheter; cardiac output, pulmonary artery
pressure and pulmonary capillary wedge pressure were measured; in
addition to taking blood samples for mixed venous blood gas tensions.
Both pulmonary and systemic vascular resistances were calculated. In
the ICU, a 12-lead ECG was done 6 and 12 hours postoperatively. In
addition, all the previous measurements by the Swan Ganz catheter
were done every 4 hours for 12 hours
Hemodynamic data were collected at 7 stages: Baseline (after
induction of anesthesia), before cardiopulmonary bypass, after coming
off bypass and starting the drug infusions, before patient transfer to
ICU and every 4 hours in ICU for 12 hours.
The demographics of patients who received study medication
show that both groups were comparable for age, height, weight, sex,
and type of surgery.
A comparable hemodynamic baseline was required, allowing a
meaningful comparison of the hemodynamic effects of both groups of drug. Examination of the baseline data suggests that the goal was
achieved.
Serial measurements of MPAP, PCWP and CVP revealed
statistically significant decreases in the Milrinone group than the
Dobutamine & Nitroglycerin group at all times points after CPB
(before patient transfer and 1st 12hs ICU). Statistically significant
increases in HR, MAP, CO and PV’O2 in the Dobutamine &
Nitroglycerin group than the Milrinone group which become more
obvious by time. In both group there were statistically significant
decreases in SVR and PVR at all times. There were no differences
regarding ischemic time, by pass time and time of extubation in both
groups.