A comparison of the acute hemodynamic effects of inhaled nitroglycerin and iloprost in patients with pulmonary hypertension undergoing mitral valve surgery.

BACKGROUND: Since the presence of pulmonary hypertension (PHT) affects the prognosis of the patients, it is important to manage and evaluate PHT. The aim of this study was to compare the hemodynamic effects of inhaled nitroglycerin and iloprost during early postoperative period, in patients with PHT undergoing mitral valve replacement surgery. MATERIALS AND METHODS: One hundred patients with PHT (mean pulmonary artery pressure (MPAP) >25 mmHg at rest), were randomized to receive either inhalation of nitroglycerin (group I; n=50) or iloprost (group II; n=50) in the postoperative period. In both groups, baseline hemodynamic parameters were recorded before the treatment (T(0)). Then, patients in group I received 20 microg.kg(-1) nitroglycerin and those in group II received 2.5 microg.kg(-1) iloprost. The same parameters were recorded immediately after the end of the treatment (T(1)). RESULTS: In both study groups MPAP and pulmonary vascular resistance (PVR) were found to be significantly lower at T(1) when compared to that of T(0) period (p<0.05). MPAP and PVR were significantly lower and mean arterial pressure (MAP) was significantly higher in group II when compared to group I at T(1) period (p<0.05). In addition to decreases in PVR and MPAP, iloprost also increased cardiac output (CO)(4.9+/-1.3 vs 5.1+/-0.9, p<0.05) and stroke volume (SV)(48+/-13 vs 56+/-13, p<0.05). CONCLUSION: Inhaled iloprost and nitroglycerin, both effectively reduce MPAP and PVR without affecting MAP, systemic vascular resistance (SVR) and CO. However, iloprost seems to be a more powerful pulmonary vasodilator, therefore we suggest iloprost inhalation in patients with severe PHT.

Continuous positive airway pressure does not improve lung function after cardiac surgery.

PURPOSE: Despite the well-documented impairment of pulmonary function after cardiopulmonary bypass, effective precautions and ideal management strategies for this problem are still under debate. This study aimed to evaluate the effects of continuous positive airway pressure (CPAP) applied during cardiopulmonary bypass on respiratory and hemodynamic variables. METHODS: In this randomized, prospective, controlled trial, 120 male patients, aged 45 to 70 yr undergoing first-time elective bypass surgery, were randomly assigned to receive either 10 cm H2O of CPAP (Group I; n = 60) during cardiopulmonary bypass, or serve as control (Group II; n = 60), where the patient's lungs were vented to atmosphere during the bypass period. RESULTS: Alveolar-arterial oxygen partial pressure difference and shunt fraction were significantly higher in the control group compared with the CPAP group after cardiopulmonary bypass (T2) and after closure of sternum (T3), (P < 0.05). No differences between groups with respect to hemodynamic variables were observed at any time. Postoperative pulmonary function variables were lower in both groups compared to baseline values. CONCLUSIONS: Continuous positive airway pressure administered during cardiopulmonary bypass decreased shunt fraction and alveolar-arterial oxygen partial pressure difference during surgery, but had no sustained effect on either variable postoperatively. We conclude that, in patients with normal preoperative pulmonary function, application of 10 cm H2O CPAP does not improve lung function after cardiac surgery.

Sternal wound complications in bilateral internal thoracic artery grafting: a comparison of the off-pump technique and conventional cardiopulmonary bypass.

BACKGROUND: Sternal wound complication is a major concern in bilateral internal thoracic artery grafting. The purpose of this study was to assess whether avoiding cardiopulmonary bypass has beneficial effects with fewer wound complications in patients receiving bilateral internal thoracic artery grafting. METHODS: Retrospective review was performed using prospectively gathered data of 69 patients who had undergone elective coronary artery bypass grafting and received conventional pedicled bilateral internal thoracic artery grafting from December 2002 through April 2004 by the same surgical team. The patients were divided into 2 groups: those who underwent coronary artery bypass grafting without cardiopulmonary bypass (off-pump group, n = 41), and those who underwent coronary artery bypass grafting with cardiopulmonary bypass (CPB group, n = 28). Chart review and 3-month follow-up were obtained for all patients. These 2 groups were compared for sternal wound complications and preoperative, intraoperative, and postoperative variables. RESULTS: Deep sternal wound infection (SWI) was seen in 1 patient (2.4%), superficial SWI in 2 patients (4.8%), and sternal dehiscence in 1 patient (2.4%) in the off-pump group. Deep SWI was seen in no patients, superficial SWI in 2 patients (7.1%) and sternal dehiscence in 2 patients (7.1%) in the CPB group. No statistically significant difference in the frequency of occurrence of sternal complications was detected between the 2 study groups. CONCLUSIONS: The results suggest that the avoidance of CPB has no beneficial effect on the number of sternal wound complications in patients receiving bilateral internal thoracic artery grafting. However, further prospective, randomized studies on large patient groups are required to assess this finding.

Effect of nitroglycerin inhalation on patients with pulmonary hypertension undergoing mitral valve replacement surgery.

BACKGROUND: The aim of this study was to investigate the postoperative hemodynamic effects of nitroglycerin inhalation on patients with pulmonary hypertension undergoing mitral valve replacement surgery. METHODS: Twenty patients who underwent mitral valve replacement surgery were included in the study. In the surgical intensive care unit, at T0 (before the inhalation of nitroglycerin), basal systemic and pulmonary hemodynamics were recorded. Then, 2.5 microg x kg-1 x min-1 nitroglycerin liquid nebulized by a 2-l gas flow of 40% oxygen and air mixture was administered to the patients who were diagnosed as having pulmonary hypertension (mean pulmonary arterial pressures > 25 mmHg). The same parameters were measured at the first (T1), third (T2), and fifth (T3) hours after the beginning of this treatment and 1 h after the end of nitroglycerin inhalation (T4). RESULTS: There were no statistically significant differences at T0, T1, T2, T3, or T4 with respect to heart rate, mean arterial pressure, systemic vascular resistance, cardiac index, mixed venous oxygen saturation, arteriovenous oxygen content difference, or arterial carbon dioxide tension. However, mean pulmonary artery pressure, pulmonary vascular resistance, and intrapulmonary shunt fraction were significantly lower, and the arterial oxygen tension/fraction of inspired oxygen ratio was higher at T1, T2, and T3 when compared to that of T0 and T4. CONCLUSION: The results suggest that nitroglycerin inhalation produces a significant reduction in both mean pulmonary artery pressure and pulmonary vascular resistance in patients after mitral valve operations without reducing mean arterial pressure and systemic vascular resistance. Therefore, it might be a safe and useful therapeutic intervention during the postoperative course.

Effect of timing of chest tube removal on development of pericardial effusion following cardiac surgery.

BACKGROUND: There are no standard criteria for the timing of drain removal. The objective of this study was to determine whether the macroscopic appearance of chest tube drainage fluid to serosanguineous may be used as a criteria for drain removal. METHODS: 2,359 patients were assessed retrospectively and 80 randomized patients were followed prospectively who underwent cardiac surgery. In both parts of the study, patients were divided into two groups according to the timing of drain removal. Group I consisted of patients whose chest tubes were removed as soon as the macroscopic appearance of the drainage fluid turned to serosanguineous. Group II consisted of patients whose chest tubes were removed at the second postoperative day when the drainage output declined to less than 50 mL in a five-hour period. In the retrospective part, cases of hemodynamically significant pericardial effusion observed within seven days postoperatively were reviewed. In the prospective part, just before the drain removal, the fluid sample hematocrit obtained from the drain lines and patients' blood hematocrit were measured and recorded. Patients were evaluated with echocardiography for pericardial effusion. RESULTS: No statistically significant difference was detected in the frequency of hemodynamically significant pericardial effusion and incidence or amount of pericardial effusion between the two study groups. The drain hematocrit to blood hematocrit ratios before drain removal showed a significant correlation with pericardial effusion. The strength of correlation between the drain hematocrit to blood hematocrit ratios before drain removal and pericardial effusion was also studied using receiver operating characteristic curve, which suggests that a drain hematocrit to blood hematocrit ratio of < or = 0.3 is strongly predictive that pericardial effusion would be absent or mild between the fifth and seventh postoperative days. CONCLUSIONS: It is safe to remove the chest tubes as soon as the macroscopic appearance of the drainage fluid turns to serosanguineous since this practically indicates cessation of active bleeding.

Daily comparison of respiratory functions between on-pump and off-pump patients undergoing CABG.

OBJECTIVE: Widespread application of on-pump revascularization procedures is increasing due to the thought of elimination of untoward effects of cardiopulmonary circuit. Thus, whether off-pump coronary artery surgery eliminates side effects especially related to respiratory functions is still controversial. Although many previous studies have evaluated these respiratory functions, daily comparison of 12 parameters was not included in any of the studies. The aim of our prospective study was to ascertain whether off-pump coronary operation improves pulmonary functions and postoperative recovery period when compared with on-pump technique and whether early discharge of patients with off-pump surgery is the result of respiratory improvement. METHODS: Eighteen patients in each group were included: on-pump group underwent coronary revascularization with cardiopulmonary bypass and off-pump with stabilization. Respiratory function tests and arterial blood gas analyses were performed preoperatively and daily after operation function tests included forced expiratory volume (FEV) in 1s, forced vital capacity (FVC), expiratory reserve volume, vital capacity, quotient of FEV in 1s to FVC, maximal voluntary ventilation (MVV), tidal volume, and forced midexpiratory flow. Blood gas analyses included partial arterial oxygen and carbon dioxide pressure, arterial pH and hematocrit (Hct). RESULTS: Preoperative pulmonary functions and arterial blood gases were not statistically significant between groups except MVV and partial arterial oxygen pressure. MVV was slightly higher in on-pump group and partial arterial oxygen pressure was slightly lower in on-pump group. During postoperative first day Hct (P=0.004) and FEV in 1s (P=0.049) values and third day partial arterial oxygen pressure (P=0.011) and Hct (P=0.011) values were lower in on-pump group. Mean extubation, duration in postoperative suit and hospital discharge times, mean blood loss were not statistically significant between groups postoperatively. CONCLUSION: Pulmonary functions and arterial blood gases were not improved in off-pump patients when compared with on-pump patients. Patients going to be surgically revascularized should not be altered to off-pump surgery merely with the hope of improving respiratory functions with off-pump technique. As the postoperative stay times at surgical theatre and hospital is not different and the extubation times were similar, early discharge of patients with off-pump surgery cannot be related merely to better preservation of respiratory functions.

Endotoxemia in coronary artery bypass surgery: a comparison of the off-pump technique and conventional cardiopulmonary bypass.

OBJECTIVES: The endotoxemia associated with cardiac surgery is thought to be dominantly influenced by the use of cardiopulmonary bypass. The objectives of this study were to assess the relative contribution of cardiopulmonary bypass on endotoxemia apart from cardiac surgical access and to improve our understanding of the potential benefits of off-pump procedures. METHODS: Thirty patients undergoing coronary artery bypass grafting were followed up prospectively. The patients were divided into 2 equal groups: those who underwent bypass grafting through a sternotomy incision without cardiopulmonary bypass (off-pump group) and those who underwent bypass grafting through a sternotomy incision with cardiopulmonary bypass (CPB group). Blood sampling for endotoxin, lactate, and cardiac index measurements were performed during the following time points: (1) after sternotomy; (2) during the coronary occlusion period in the off-pump group and during aortic clamping in the CPB group; (3) after removal of the coronary occlusion sutures in the off-pump group and after removal of the aortic clamp in the CPB group; (4) 30 minutes after the completion of all distal anastomoses in the off-pump group and immediately after weaning from cardiopulmonary bypass in the CPB group; (5) 1 hour postoperatively; and (6) 12 hours postoperatively. RESULTS: Endotoxin and lactate levels were significantly (P <.05) lower in the off-pump group at all sampling time points, except after sternotomy. CONCLUSIONS: In conclusion, this study has shown that endotoxemia during coronary artery bypass surgery seems mainly to be associated with cardiopulmonary bypass procedure. The relatively lower endotoxin levels observed in off-pump surgery might contribute to improved postoperative recovery.