Cause Of Hemodynamic Instability Research Articles

Mechanisms of hemodynamic changes during off-pump coronary artery bypass surgery.

To describe the mechanisms of hemodynamic changes during off-pump coronary artery bypass graft surgery (OP-CABG). Pertinent medical literature in the English and French languages was identified through a Medline computerized literature search and a manual search of selected articles, using off-pump coronary artery surgery, beating heart surgery, hemodynamic, and transesophageal echocardiography as key words. Human and animal studies were included. Hemodynamic variations in OP-CABG may be due to mobilization and stabilization of the heart, or myocardial ischemia occurring during coronary occlusion. Suction type and compression type stabilizers produce hemodynamic effects through different mechanisms. Heart dislocation (90 degrees anterior displacement) and compression of the right ventricle to a greater extent than the left ventricle are responsible for hemodynamic alterations when using suction type stabilizers. Compression of the left ventricular outflow tract and abnormal diastolic expansion secondary to direct deformation of the left ventricular geometry are proposed mechanisms for hemodynamic derangements with compression type stabilizer. Coronary occlusion during the anastomosis can have additional effects on left ventricular function, depending on the status of collateral flow. The value and limitations of electrocardiographic (ECG), hemodynamic and echocardiographic monitoring modalities during OP-CABG are reviewed. In summary, hemodynamic changes which can either be secondary to the stabilization technique or to transient ischemia represent an important diagnostic challenge during off-bypass procedures. The mechanism can vary according to the stabilization system. Current monitoring such as ECG and hemodynamic monitoring are used but remain limited in establishing the cause of hemodynamic instability. Transesophageal echocardiography is used in selected patients to diagnose the etiology of hemodynamic instability and can direct therapy, particularly in those with severe myocardial systolic and diastolic dysfunction, mild to moderate mitral regurgitation, or for patients who are unstable during the procedure.

Transesophageal echocardiography in critically ill patients.

To evaluate the safety and utility of transesophageal echocardiography performed by intensive care physicians in critically ill patients. Retrospective chart review. A 24-bed multidisciplinary adult intensive care unit in a 692-bed tertiary referral teaching hospital. Two hundred fifty-five intensive care patients. We studied 255 consecutive intensive care patients who underwent transesophageal echocardiography between January 1996 and January 2000. Three hundred eight transesophageal echocardiography studies were successfully performed; the probe could not be passed in one patient with a cervical fracture. The indications included unexplained hypotension (40%), known or suspected endocarditis (27%), assessment of ventricular function (15%), pulmonary edema (5%), source of embolus (4%), assessment of aorta (4%), and other (5%). In 67% of hypotensive patients, transesophageal echocardiography revealed the cause of hemodynamic instability, leading to a management change and improvement in blood pressure in 31%. This included surgery in 22% without the need for additional tests. Overall, transesophageal echocardiography findings led to a significant change in management in 32% of all studies performed. One patient receiving continuous positive airways pressure suffered pulmonary aspiration during tracheal intubation before transesophageal echocardiography, two patients had hypotension associated with sedative medication, and there was one case of oropharyngeal bleeding after probe insertion. Transesophageal echocardiography when performed by intensive care physicians is a safe procedure and provides useful information for the evaluation and management of critically ill patients.

Circulatory management of the unstable cardiac patient.

The objective of this article is to provide an orderly and concise approach to the treatment of the unstable cardiac surgery patient. The common causes of hemodynamic instability in this patient population are reviewed. The various pharmacologic, mechanical, and electric therapeutic options available for each clinical situation are explored, and a sequential treatment algorithm is developed.

Incidence of Venous Air Embolism During Craniectomy for Craniosynostosis Repair

BackgroundInvestigations to determine the incidence of venous air embolism in children undergoing craniectomy for craniosynostosis repair have been limited, although venous air embolism has been suspected as the cause of hemodynamic instability and sometimes death. A precordial Doppler ultrasonic pr

Incidence of venous air embolism during craniectomy for craniosynostosis repair.

Investigations to determine the incidence of venous air embolism in children undergoing craniectomy for craniosynostosis repair have been limited, although venous air embolism has been suspected as the cause of hemodynamic instability and sometimes death. A precordial Doppler ultrasonic probe is an accepted method for detection of venous air embolism and is readily available at most institutions. A prospective study was conducted using a precordial Doppler ultrasonic probe in children undergoing craniectomy for craniosynostosis repair. The Doppler signal was continuously monitored intraoperatively for characteristic changes of venous air embolism. A recording was made of the precordial Doppler probe pulses, which was later reviewed by a neuroanesthesiologist, blinded to the intraoperative events. This information was correlated with the intraoperative events and episodes of venous air embolism were graded. Twenty-three patients were enrolled in the study during the 2-yr study period. Nineteen patients (82.6%) demonstrated 64 episodes of venous air embolism; six patients (31.6%) had hypotension associated with venous air embolism. Thirty-two episodes of hypotension were demonstrated in eight patients (34.7%). None of the patients developed cardiovascular collapse. The incidence of venous air embolism in our study of 23 children undergoing craniectomy for craniosynostosis was 82.6%. Though most episodes of venous air embolism during craniosynostosis repair are without hemodynamic consequences, the preemptive placement of a precordial Doppler ultrasonic probe is a noninvasive, economic, and safe method for the detection of venous air embolism. Prompt recognition may allow for the early initiation of therapy, thereby decreasing morbidity and mortality rates related to venous air embolism.

Contaminated platelets as a cause of hemodynamic instability after cardiopulmonary bypass

Contaminated platelets as a cause of hemodynamic instability after cardiopulmonary bypass