Khalil Jabbour

Pulse Pressure Variation Predicts Fluid Responsiveness in Elderly Patients After Coronary Artery Bypass Graft Surgery

OBJECTIVE To assess the ability of pulse pressure variation to predict fluid responsiveness in mechanically ventilated elderly patients after coronary artery bypass graft surgery. DESIGN A prospective, interventional study. SETTING An academic, tertiary referral hospital. PARTICIPANTS Sixty patients >70 years old and mechanically ventilated after coronary artery bypass graft surgery. INTERVENTIONS Intravascular volume expansion using 6% hydroxyethyl starch solution, 7 mL/kg over 20 minutes. MEASUREMENTS AND MAIN RESULTS Heart rate, arterial blood pressure, pulse pressure variation, central venous pressure, pulmonary artery occlusion pressure, and stroke volume index were measured immediately before and after volume expansion. Fluid responsiveness was defined as an increase in stroke volume index ≥ 15% after volume expansion. Forty-one patients were fluid responders and 19 patients were nonresponders. In contrast to central venous pressure or pulmonary artery occlusion pressure, pulse pressure variation was higher in the responders than in the nonresponders (22 ± 6% v 9.3 ± 3%, p = 0.001) and correlated with the percent changes in the stroke volume index after volume expansion (r = 0.47, p = 0.001). The area under the receiver operating characteristic curve for pulse pressure variation was 0.85 (95% confidence interval 0.75-0.94). The threshold value of 11.5% allowed the discrimination between responders and nonresponders with a sensitivity of 80% and a specificity of 74%. CONCLUSIONS Pulse pressure variation is a reliable predictor of fluid responsiveness in mechanically ventilated elderly patients after coronary artery bypass graft surgery.

The effect of low-dose intravenous ketamine on continuous intercostal analgesia following thoracotomy

Ketamine, a noncompetitive N-methyl-d-aspartate antagonist, provides analgesia and prevents chronic pain following thoracotomy. The study was aimed to assess the effect of intravenous low-dose ketamine on continuous intercostal nerve block analgesia following thoracotomy. The study was a prospective, randomized, double-blinded, and placebo-controlled clinical study, performed in a single university hospital. Sixty patients, undergoing elective lobectomy through an open posterolateral thoracotomy, were included. For postoperative pain, all patients received a continuous intercostal nerve block with bupivacaine plus intravenous paracetamol and ketoprofen. In addition, patients were randomized to have intravenous ketamine (0.1 mg/kg as a preincisional bolus followed by a continuous infusion of 0.05 mg/kg/h) in group 1 or intravenous placebo in group 2. Patients reporting a visual analog scale pain score at rest ≥40 mm received intravenous morphine sulfate as rescue analgesia. The following parameters were assessed every 6 hours for 3 postoperative days: Visual analog scale pain scores at rest and during coughing, requirement of rescue analgesia with morphine, Ramsay sedation scores and psychomimetic adverse effects. Both the groups were statistically comparable regarding visual analog scale pain scores at rest (P=0.75) and during coughing (P=0.70), number of morphine deliveries (P=0.17), cumulative dose of rescue morphine (P=0.2), sedation scores (P=0.4), and psychomimetic adverse effects (P=0.09). Intravenous low-dose ketamine, when combined with continuous intercostal nerve block, did not decrease acute pain scores and supplemental morphine consumption following thoracotomy.

Correlation between central venous oxygen saturation and oxygen delivery changes following fluid therapy

Background: The rationale for using central venous oxygen saturation (ScvO2) in various clinical scenarios is that it reflects the balance between oxygen delivery (DO2) and demands. In this study, we evaluated the correlation between ScvO2 and DO2 changes (ΔDo2, ΔScvO2) in patients receiving fluid therapy following coronary surgery. We also correlated the changes of mean arterial pressure (ΔMAP) and central venous pressure (ΔCVP), with ΔDO2.

Correlation between Central Venous - Arterial Carbon Dioxide Tension Gradient and Oxygen Delivery Changes Following Fluid Therapy

Background: Central venous-arterial carbon dioxide (CVA-CO2) tension gradient was related to low cardiac output after coronary surgery. The objective of this study was to assess the correlation between CVA-CO2 tension gradient and oxygen delivery (DO2) changes following fluid therapy in coronary surgery. Methods: A prospective interventional study was conducted in a cardiac surgery intensive care unit. Forty consecutive sedated and mechanically ventilated adult patients, with a cardiac index < 2.3 L/min/m² and a pulmonary artery occlusion pressure ≤ 12 mmHg following coronary surgery, were included. All patients received a 500 ml bolus of an isotonic crystalloid solution over 20 min. Concomitant hemodynamic parameters, arterial and central venous blood gases were measured before (T0) and after (T1) volume loading. Means were compared by Student’s test and correlations by Spearmen coefficient”. P ≤ 0.05 was considered to be significant. Results: CVA-CO2 gradient decreased (12.6 ± 3.0 vs 10.2 ± 3.7 mmHg; p = 0.01) and DO2 increased (312 ± 57 vs 357 ± 81 l/min/m²; p = 0.001) significantly from T0 to T1. The correlation between CVA-CO2 gradient changes and DO2 changes was negative and statistically significant (r = -0.38; p=0.015). Conclusion: CVA-CO2 gradient and DO2 changes were inversely and significantly correlated in patients receiving fluid therapy following coronary surgery. In this context, CVA-CO2 gradient changes could be used as an indicator to guide volume loading and to assess its effect on DO2.

Generalized Skin Mottling: An Early Sign of Acute Mesenteric Infarction After Cardiac Surgery

To the Editor: Acute mesenteric infarction after cardiac surgery is uncommon (0.1%-0.3%) but associated with a very high mortality rate (60%-90%).1-3 Early diagnosis is of critical importance in patients with mesenteric infarction because the only chance of cure is prompt surgical intervention.4 However, critically ill patients after cardiac surgery are often ventilated and sedated, and, therefore, signs and symptoms of abdominal pathology are masked. The difficulty in making the diagnosis of mesenteric infarction after cardiac surgery contributes heavily to its catastrophic mortality. We are reporting the cases of 2 cardiac surgery patients who presented generalized skin mottling as an early clinical sign of postoperative acute mesenteric infarction. The first patient was a 73-year-old man with a medical history of heavy smoking, hyperlipidemia, and cerebral vascular disease. He had an uneventful triple-vessel revascularization with extracorporeal circulation and was transferred to our intensive care unit under deep sedation and mechanical ventilation. On admission, the patient had generalized skin mottling characterized by unevenly distributed colored areas of different shades all over the lower limbs, the abdomen, and the thorax. Physical examination was negative. Hemodynamic parameters, urine output, arterial and mixed venous blood gases, standard bicarbonate, and lactate were within normal limits. After tracheal extubation at the 8th postoperative hour, the patient complained of abdominal pain progressively associated with oliguria and metabolic acidosis. The diagnosis of mesenteric ischemia was confirmed by an abdominal computed tomography scan and colonoscopy showing ischemic changes in the colon. An emergency laparotomy showed diffuse necrosis of the large intestine. The patient had a total colon resection with end ileostomy but died on the 4th postoperative day as a result of multiple-organ failure. The second patient was an 84-year-old man with a medical history of chronic renal failure and diabetes who had an uneventful mitral and aortic valves replacement. He presented in the immediate postoperative period with generalized skin mottling with no other clinical, hemodynamic, or metabolic disorder. After extubation, on day 1, the patient showed peritonitis signs associated with dramatic increases in leukocyte count, arterial lactate, and serum amylase. An exploratory laparotomy revealed massive necrosis of the small and large intestine. The patient had a subtotal bowel resection with stoma. He died on the 11th postoperative day as a result of sepsis. In critically ill patients, skin mottling is a clinical sign of vasoconstriction and tissue hypoperfusion. Mottling was reported as one of the presenting symptoms in 46% of patients from a general population undergoing surgery for mesenteric infarction.5 It is caused by the release of vasoactive products from the ischemic intestinal mucosa. These cases show that generalized skin mottling might be an early sign of mesenteric infarction in ventilated and sedated patients after cardiac surgery. It appeared several hours before abdominal clinical signs, hemodynamic deterioration, and metabolic acidosis. We conclude that mesenteric infarction should be suspected in sedated patients with generalized skin mottling after cardiac surgery. Patients presenting with this clinical sign should be woken up rapidly so that abdominal symptoms can be accurately evaluated and further diagnostic investigations undertaken.

Acute thrombosis of abdominal aortic aneurysm during cardiac surgery.

Aortic thrombosis has been described in the medical literature as a rare and catastrophic complication of abdominal aortic aneurysms. However, it has only been reported once in cardiac surgical settings. We report a unique case of thrombosis of an abdominal aortic aneurysms during the course of cardiac surgery, in a fully anticoagulated patient on cardiopulmonary bypass. Prompt diagnosis and immediate surgical management were critical for a successful outcome.

Tissue Oxygen Saturation (StO2) Is Not Correlated with Mixed Venous Oxygen Saturation (SvO2) and Fails to Detect Adverse Events during and after Coronaryartery Bypass Graft (CABG) Surgery

Introduction : Mixed venous oxygen saturation (SvO2), is an invasive monitoring technique that reflects the balance between systemic oxygen transport and tissue oxygen consumption. Whereas tissue oxygen saturation (StO2) is a noninvasive technique that allows early detection of tissue hypoperfusion. The purpose of this study is to evaluate StO2 in patients undergoing elective coronary surgery: single cardiopulmonary bypass (CPB), and to find a correlation between StO2 and SvO2. Material and Methods : All patients scheduled for elective coronary surgery from May to July 2013, were included in the study. The anesthetic management and hemodynamic monitoring were the same. The following parameters: BP, HR, CI, SaO2, SvO2, StO2 at the eminence thenar, Hb and ΔPCO2 were monitored at the following times : T1: before anesthesia induction, T2 : after induction, T3 : 30 min after the beginning of CPB, T4 : after the weaning from CBP, T5 : H 12, at D1, D2 and at the occurrence of an adverse outcome such as anemia, hypotension, arrhythmia, hypoxia, fever with or without chills.. Results : Forty-five patients were included in this prospective study. Forty patients had 63 events : low cardiac output, isolated hypotension, hypoxia, anemia, AFib and atrial flutter. There was no statistically significant difference in StO2 from pre-induction till up to 2 days postoperatively, except after the weaning from CPB and 12 hours postoperatively. No correlation was noted between SvO2 and StO2 during the events that occurred both during and after the operation. Conclusion : Microcirculation at the eminence thenar may be altered after CPB. This fact is reflected by the decrease in StO2 that was noted immediately after CPB and that returned to normal 12 hours postoperatively. However, StO2 is not correlated with SvO2 upon the occurrence of an event during or after elective cardiac surgery. Further studies are needed to show the benefit of this noninvasive monitoring in cardiac surgery.

Hemodynamics With Postoperative Pacing

the carotid artery indeed needed surgical intervention.7 Ultrasound guidance for the placement of central catheters has increased in operating rooms. It is a very helpful tool in placing central venous catheters. However, as this case shows, ultrasound can further be useful in managing the complications such as accidental carotid artery punctures. The intimal tear with a pseudoaneurysm, which may not have been recognized from external examination alone, can be identified quickly and assessed by using ultrasound. Routine ultrasound examination of the carotid artery after its accidental puncture should be encouraged.

Combined sciatic, femoral and obturator nerve blocks for an infra-inguinal arterial bypass graft surgery

Sir, Acute transient swelling of the parotid gland after general anesthesia, referred to as anesthesia mumps, is a rare clinical entity. It is a benign and noninfectious complication. A 26-year-old male was operated due to a T4 burst fracture. General anesthesia was induced, and the patient was placed in the prone position. The head was turned to the right side and the left side of the face was placed on a soft pad. Posterior stabilization, which lasted about 5 h, was performed and the patient was extubated without any problem. Four hours after the surgery, a painful swelling on the left pre-auricular and post-auricular areas extending to the angle of the mandible was noted. Clinical examination showed diffuse edema and induration over the parotid gland. We performed ultrasonography, which showed enlargement of the left parotid gland and dilatation of the parotid duct. The swelling started to resolve at 48 h and subsided completely on day 6. The etiology of anesthesia mumps is unclear. Among the implicated mechanisms are the increase in intra-oral pressure due to straining and/or coughing during anesthesia and retrograde passage of air into the parotid gland via the Stenon duct, obstruction of the Stenon duct due to head positioning, retention of secretions and dehydration. In our case, not only mechanical compression but also manipulation of the oropharyngeal cavity due to endotracheal intubation may be considered. When we first saw the case, we thought that the swelling might be subcutaneous emphysema. However, there was no crepitation by palpation. Besides, chest roentgenogram had no evidence of pneumothorax. What can be done to prevent such a problem? The most important measure is to use soft pads to prevent the parotid gland from being subjected to direct compression when the patients undergo a lengthy surgery and lie in the prone position. Furthermore, it is critical to keep the patient normovolemic. In conclusion, anesthesia mumps may occur in the first few hours of the post-operative period. It has no clinical significance and patients fully recover within a few days without any treatment. The main priority should be to eliminate the anxieties of both the patient and the family.