释义 |
pericardiocentesis
Pericardiocentesis DefinitionPericardiocentesis is the removal by needle of pericardial fluid from the sac surrounding the heart for diagnostic or therapeutic purposes.PurposeThe pericardium, the sac (or membrane) that surrounds the heart muscle, normally contains a small amount of fluid that cushions and lubricates the heart as the heart expands and contracts. When too much fluid gathers in the pericardial cavity, the space between the pericardium and the outer layers of the heart, a condition known as pericardial effusion occurs. Abnormal amounts of fluid may result from:- pericarditis (caused by infection, inflammation)
- trauma (producing blood in the pericardial sac)
- surgery or other invasive procedures performed on the heart
- cancer (producing malignant effusions)
- myocardial infarction, congestive heart failure
- renal failure
Possible causes of pericarditis include chest trauma, systemic infection (bacterial, viral, or fungal), myocardial infarction (heart attack), or tuberculosis. When pericarditis is suspected, pericardiocentesis may be advisable in order to obtain a fluid sample for laboratory analysis to identify the underlying cause of the condition.Pericardiocentesis is also used in emergency situations to remove excessive accumulations of blood or fluid from the pericardial sac, such as with cardiac tamponade. When fluid builds up too rapidly or excessively in the pericardial cavity, the resulting compression on the heart impairs the pumping action of the vascular system. Cardiac tamponade is a life-threatening condition that requires immediate treatment.PrecautionsWhenever possible, an echocardiogram (ultrasound test) should be performed to confirm the presence of the pericardial effusion and to guide the pericardiocentesis needle during the procedure. Because of the risk of accidental puncture to major arteries or organs in pericardiocentesis, surgical drainage may be a preferred treatment option for pericardial effusion in non-emergency situations.DescriptionThe patient's vital signs are monitored throughout the procedure, and an ECG tracing is continuously run. If time allows, sedation is administered, the puncture site is cleaned with an antiseptic iodine solution, and a local anesthetic is injected into the skin to numb the area. The patient is instructed to remain still. The physician performing pericardiocentesis will insert a syringe with an attached cardiac needle slowly into the chest wall until the needle tip reaches the pericardial sac. The patient may experience a sensation of pressure as the needle enters the membrane. When the needle is in the correct position, the physician will aspirate, or withdraw, fluid from the pericardial sac.When the procedure is performed for diagnostic purposes, the fluid will be collected into specimen tubes for laboratory analysis. If the pericardiocentesis is performed to treat a cardiac tamponade or other significant fluid build-up, a pericardial catheter may be attached to the needle to allow for continuous drainage.After the cardiac needle is removed, pressure is applied to the puncture site for approximately five minutes, and the site is then bandaged.PreparationPrior to pericardiocentesis, the test procedure is explained to the patient, along with the risks and possible complications involved, and the patient is asked to sign an informed consent form. If the patient is incapacitated, the same steps are followed with a family member.No special diet or fasting is required for the test. After the patient changes into a hospital gown, an intravenous line is inserted into a vein in the arm. The IV will be used to administer sedation, and any required medications or blood products. Leads for an electrocardiogram (ECG) tracing are attached to the patient's right and left arms and legs, and the fifth lead is attached to the cardiac needle used for the procedure. The patient is instructed to lie flat on the table, with the upper body elevated to a 60 degree angle.AftercareThe site of the puncture and any drainage catheter should be checked regularly for signs of infection such as redness and swelling. Blood pressure and pulse are also monitored following the procedure. Patients who experience continued bleeding or abnormal swelling of the puncture site, sudden dizziness, difficulty breathing, or chest pains in the days following a pericardiocentesis procedure should seek immediate medical attention.RisksPericardiocentesis is an invasive procedure, and infection of the puncture site or pericardium is always a risk. Possible complications include perforation of a major artery, lung, or liver. The myocardium, the outer muscle layer of the heart, could also be damaged if the cardiac needle is inserted too deeply.Normal resultsNormal pericardial fluid is clear to straw-colored in appearance with no bacteria, blood, cancer cells or pathogens. There is typically a minimal amount of the fluid (10-50 ml) in the pericardial cavity.Abnormal resultsA large volume of pericardial fluid (over 50 ml) indicates the presence of pericardial effusion. Laboratory analysis of the fluid can aid in the diagnosis of the cause of pericarditis. The presence of an infectious organism such as staphylococcus aureus is a sign of bacterial pericarditis. Excessive protein is present in cases of systemic lupus erythematosus or myocardial infarction (heart attack). An elevated white blood count may point to a fungal infection. If the patient has a hemorrhage, a cardiac rupture, or cancer, there may be blood in the pericardial fluid.ResourcesBooksWeinstock, Doris et al. eds. "Body system Tests: Cardiovascular System." In Illustrated Guide to Diagnostic Tests, 2nd edition. Springhouse, PA: Springhouse Corporation, 1998.OrganizationThe American Heart Association. National Center. 7272 Greenville Avenue, Dallas, Texas 75231. (800) AHA-USA 1. http://www.americanheart.org.Key termsCardiac tamponade — Compression and restriction of the heart that occurs when the pericardium fills with blood or fluid. This increase in pressure outside the heart interferes with heart function and can result in shock and/or death.Catheter — A long, thin, flexible tube used to drain or administer fluids.Echocardiogram — An imaging test using high-frequency sound waves to obtain pictures of the heart and surrounding tissues.Electrocardiogram — A cardiac test that measures the electrical activity of the heart.Myocardium — The middle layer of the heart wall.Pericardium — A double membranous sac that envelops and protects the heart.pericardiocentesis [per″ĭ-kahr″de-o-sen-te´sis] surgical puncture into the pericardial space and aspiration of fluid for therapeutic or diagnostic purposes. Therapeutically, the procedure is used as an emergency measure to relieve life-threatening cardiac tamponade. Other clinical situations in which it may be done include pericardial effusion, traumatic perforation or rupture of the myocardium, and effusion secondary to a tumor or chest injury. Since serious dysrhythmias can develop, cardiac monitoring is necessary throughout the procedure. Blood pressure, pulse, and heart rhythm also are monitored during it and for 24 hours afterwards. Serious and life-threatening immediate complications are possible, such as perforation of a ventricle, laceration of a coronary artery, aspiration of blood from a heart chamber, or air embolism. Infection and hydropneumothorax can develop later. per·i·car·di·o·cen·te·sis (per-i-kar'dē-ō-sen-tē'sis), Needle or catheter drainage of the pericardium. Synonym(s): pericardial tap, pericardicentesis [peri- + G. kardia, heart, + kentēsis, puncture] pericardiocentesis Cardiology Insertion of a long needle in the pericardial sac to obtain fluids and cells for analysis of inflammation or tumor cells Indications Controversial; experts believe pericardiocentesis should be limited to emergencies, and advocate an open–surgical approach, it is used to detect bacterial or tuberculous pericarditis or CA Complications Laceration of coronary arteries, lungs, or liver, arrhythmia due to needle irritation, vasovagal arrest, pneumothorax, infection Pericardiocentesis--Normal values Appearance Clear to straw-colored Cells RBCs None WBCs < 300/mm3 Glucose 70-100 g/dL Protein < 4 0 g/L Volume Minimal, usually ±20 mL per·i·car·di·o·cen·te·sis (per'i-kahr'dē-ō-sen-tē'sis) Needle or catheter drainage of the pericardium. [peri- + G. kardia, heart, + kentēsis, puncture] |