Central Venous Pressure Monitoring

Central venous pressure (CVP) describes the pressure of blood in the thoracic vena cava, near the right atrium of the heart. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system. It is a good approximation of right atrial pressure, which is a major determinant of right ventricular end diastolic volume (right ventricular preload).

CVP can be measured by connecting the patient's central venous catheter to a special infusion set which is connected to a small diameter water column. If the water column is calibrated properly the height of the column indicates the CVP.

Factors which increase CVP are:

• Hypervolemia
• forced exhalation
• Tension pneumothorax
• Heart failure
• Pleural effusion
• Decreased cardiac output

Factors which decrease CVP are:

• Hypovolemia
• Deep inhalation

Chest Tube Thoracostomy (CTT)

The free end of the tube is usually attached to an underwater seal, below the level of the chest to allow the fluid or air to move from the pleural space, preventing anything returning to the chest.

Sizes of Chest Tube:
Newborn = 12-14 Fr
Child = 18 Fr
Adult or Teen Male = 28-32 Fr
Pp Adult or Teen Female = 28 Fr

A chest tube is a flexible plastic tube that is inserted through the side of the chest into the pleural space.

Indications

Pneumothorax: accumulation of air in the pleural space
Pleural effusion: accumulation of fluid in the pleural space
Chylothorax: a collection of lymphatic fluid in the pleural space
Empyema: a pyogenic infection of the pleural space
Hemothorax: accumulation of blood in the pleural space
Hydrothorax: accumulation of serous fluid in the pleural space

Contraindications

Contraindications to chest tube placement include refractory coagulopathy, lack of cooperation by the patient, and diaphragmatic hernia. Additional contraindications include scarring in the pleural space (adhesions)

Insertion site
- 5th intercostal space slightly anterior to the mid axillary line, or
- in an area described as the "safe zone", a region bordered by: the lateral border of pectoralis major, a horizontal line inferior to the axilla, the anterior border of latissimus dorsi and a horizontal line superior to the nipple

Procedure

A small incision is made over the "safe zone" after injection of a local anesthesia, and a passage is made through the skin and muscle into the chest. The tube is placed through this passage.

Once the tube is in place it is sutured to the skin to prevent it falling out and a dressing applied to the area.

A chest radiograph confirms the location of the drain.

The tube stays in for as long as there is air or fluid to be removed, or risk of air gathering.

Chest Drainage Canister

There are generally three chambers.
1. The first chamber is a collecting chamber.
2. The second is the "water seal" chamber which acts as a one way valve. Air bubbling through the water seal chamber is usual when the patient coughs or exhales but may indicate, if continual, a pleural or system leak that should be evaluated critically. It can also indicate a leak of air from the lung.
3. The third chamber is the suction control chamber. The height of the water in this chamber determines the negative pressure of the system. Bubbling should be kept a gentle bubble to limit evaporating the fluid. Increased wall suction does not increase the negative pressure of the system.

Complications

Major complications are hemorrhage, infection, and reexpansion pulmonary edema. Chest tube clogging can also be a major complication if it occurs in the setting of bleeding or the production of significant air or fluid. When chest tube clogging occurs in this setting, a patient can suffer from pericardial tamponade, tension pneumothorax, or in the setting of infection, an empyema. All of these can lead to prolonged hospitilization and even death. To minimize potential for clogging, surgeons often employ larger diameter tubes. These large diameter tubes however, contribute significantly to chest tube related pain. Even larger diameter chest tubes can clog.[4] In most cases, the chest tube related pain goes away after the chest tube is removed, however, chronic pain related to chest tube induced scarring of the intercostal space is not uncommon.

Injury to the liver, spleen or diaphragm is possible if the tube is placed inferior to the pleural cavity. Injuries to the thoracic aorta and heart have also been described.

Minor complications include a subcutaneous hematoma or seroma, anxiety, shortness of breath (dyspnea), and cough (after removing large volume of fluid).

Subcutaneous emphysema indicates backpressure created by a clogged drain or insufficient negative pressure.

Glasgow Coma Scale

Best eye response (E)

There are 4 grades starting with the most severe:

1. No eye opening
2. Eye opening in response to pain. (Patient responds to pressure on the patient’s fingernail bed; if this does not elicit a response, supraorbital and sternal pressure or rub may be used.)
3. Eye opening to speech. (Not to be confused with an awaking of a sleeping person; such patients receive a score of 4, not 3.)
4. Eyes opening spontaneously

Best verbal response (V)

There are 5 grades starting with the most severe:

1. No verbal response
2. Incomprehensible sounds. (Moaning but no words.)
3. Inappropriate words. (Random or exclamatory articulated speech, but no conversational exchange)
4. Confused. (The patient responds to questions coherently but there is some disorientation and confusion.)
5. Oriented. (Patient responds coherently and appropriately to questions such as the patient’s name and age, where they are and why, the year, month, etc.)

Best motor response (M)

There are 6 grades starting with the most severe:

1. No motor response
2. Extension to pain (abduction of arm, internal rotation of shoulder, pronation of forearm, extension of wrist, decerebrate response)
3. Abnormal flexion to pain (adduction of arm, internal rotation of shoulder, pronation of forearm, flexion of wrist, decorticate response)
4. Flexion/Withdrawal to pain (flexion of elbow, supination of forearm, flexion of wrist when supra-orbital pressure applied ; pulls part of body away when nailbed pinched)
5. Localizes to pain. (Purposeful movements towards painful stimuli; e.g., hand crosses mid-line and gets above clavicle when supra-orbital pressure applied.)
6. Obeys commands. (The patient does simple things as asked.)

Interpretation

Individual elements as well as the sum of the score are important. Hence, the score is expressed in the form "GCS 9 = E2 V4 M3 at 07:35".

Generally, brain injury is classified as:

• Severe, with GCS ≤ 8
• Moderate, GCS 9 - 12
• Minor, GCS ≥ 13.

Tracheal intubation and severe facial/eye swelling or damage make it impossible to test the verbal and eye responses. In these circumstances, the score is given as 1 with a modifier attached e.g. 'E1c' where 'c' = closed, or 'V1t' where t = tube. A composite might be 'GCS 5tc'. This would mean, for example, eyes closed because of swelling = 1, intubated = 1, leaving a motor score of 3 for 'abnormal flexion'. Often the 1 is left out, so the scale reads Ec or Vt.

The GCS has limited applicability to children, especially below the age of 36 months (where the verbal performance of even a healthy child would be expected to be poor). Consequently the Pediatric Glasgow Coma Scale, a separate yet closely related scale, was developed for assessing younger children.

Revisions

• Glasgow Coma Scale: While the 15 point scale is the predominant one in use, this is in fact a modification and is more correctly referred to as the Modified Glasgow Coma Scale. The original scale was a 14 point scale, omitting the category of 'abnormal flexion'. Some centres still use this older scale, but most (including the Glasgow unit where the original work was done) have adopted the modified one.

Tracheal intubation

Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequently performed in critically injured, ill or anesthetized patients to facilitate ventilation of the lungs, including mechanical ventilation, and to prevent the possibility of asphyxiation or airway obstruction. The most widely used route is orotracheal, in which an endotracheal tube is passed through the mouth and vocal apparatus into the trachea. In a nasotracheal procedure, an endotracheal tube is passed through the nose and vocal apparatus into the trachea. Other methods of intubation involve surgery and include the cricothyrotomy (used almost exclusively in emergency circumstances) and the tracheotomy, used primarily in situations where a prolonged need for airway support is anticipated.

USE OF ANESTHESIA
Intubation is usually performed after administration of general anesthesia and a neuromuscular-blocking drug. It can however be performed in the awake patient with local or topical anesthesia, or in an emergency without any anesthesia at all.

PROCEDURE
1. An anesthesiologist opens the patient's mouth by separating the lips and pulling on the upper jaw with the index finger. Holding a laryngoscope in the left hand, he or she inserts it into the mouth of the patient with the blade directed to the right tonsil.
2. Once the right tonsil is reached, the laryngoscope is swept to the midline, keeping the tongue on the left to bring the epiglottis into view. The laryngoscope blade is then advanced until it reaches the angle between the base of the tongue and the epiglottis.
3. Next, the laryngoscope is lifted upwards towards the chest and away from the nose to bring the vocal cords into view. Often an assistant has to press on the trachea to provide a direct view of the larynx.
4. The anesthesiologist then takes the endotracheal tube, made of flexible plastic, in the right hand and starts inserting it through the mouth opening. The tube is inserted through the cords to the point that the cuff rests just below the cords.
5. Finally, a balloon cuff is typically inflated just above the far end of the tube to help secure it in place, to prevent leakage of respiratory gases, and to protect the tracheobronchial tree from receiving undesirable material such as stomach acid.
6. The tube is then secured to the face or neck and connected to a T-piece, anesthesia breathing circuit, bag valve mask device, or a mechanical ventilator.
6. Using a stethoscope , the anesthesiologist listens for breathing sounds to ensure correct placement of the tube.

COMPLICATIONS
Tracheal intubation can be associated with minor complications such as broken teeth or lacerations of the tissues of the upper airway. It can also be associated with potentially fatal complications such as pulmonary aspiration of stomach contents which can result in a severe and sometimes fatal chemical aspiration pneumonitis, or unrecognized intubation of the esophagus which can lead to potentially fatal anoxia.

INDICATIONS

Depressed level of consciousness - Damage to the brain (such as from a massive stroke, non-penetrating head injury, intoxication or poisoning) may result in a depressed level of consciousness. When this becomes severe to the point of stupor or coma (defined as a score on the Glasgow Coma Scale of less than 8),[3] dynamic collapse of the extrinsic muscles of the airway can obstruct the airway, impeding the free flow of air into the lungs. Furthermore, protective airway reflexes such as coughing and swallowing may be diminished or absent. Tracheal intubation is often required to restore patency (the relative absence of blockage) of the airway and protect the tracheobronchial tree from pulmonary aspiration of gastric contents.

Hypoxemia - Intubation may be necessary for a patient with decreased oxygen content and oxygen saturation of the blood caused when their breathing is inadequate (hypoventilation), suspended (apnea), or when the lungs are unable to sufficiently transfer gasses to the blood. Such patients, who may be awake and alert, are typically critically ill with a multisystem disease or multiple severe injuries.[1] Examples of such conditions include cervical spine injury, multiple rib fractures, severe pneumonia, acute respiratory distress syndrome (ARDS), or near-drowning. Specifically, intubation is considered if the arterial partial pressure of oxygen (PaO2) is less than 60 millimeters of mercury (mm Hg) while breathing an inspired O2 concentration (FIO2) of 50% or greater. In patients with elevated arterial carbon dioxide, an arterial partial pressure of CO2 (PaCO2) greater than 45 mm Hg in the setting of acidemia would prompt intubation, especially if a series of measurements demonstrate a worsening respiratory acidosis. Regardless of the laboratory values, these guidelines are always interpreted in the clinical context.[5]

Airway obstruction - Actual or impending airway obstruction is a common indication for intubation of the trachea. Life-threatening airway obstruction may occur when a foreign body becomes lodged in the airway; this is especially common in infants and toddlers. Severe blunt or penetrating injury to the face or neck may be accompanied by swelling and an expanding hematoma, or injury to the larynx, trachea or bronchi. Airway obstruction is also common in people who have suffered smoke inhalation or burns within close to the airway or epiglottitis caused by infection. Sustained generalized seizure activity and angioedema are other common causes of life-threatening airway obstruction which may require tracheal intubation to secure the airway.[1]

Manipulation of the airway - Diagnostic or therapeutic manipulation of the airway (such as bronchoscopy, laser therapy or stenting of the bronchi) may intermittently interfere with the ability to breathe; intubation may be necessary in such situations.[4]

EQUIPMENT

Laryngoscopes

Laryngoscope handles with an assortment of Miller blades (large adult, small adult, child, infant and newborn)










This device is designed to allow the laryngoscopist to directly view the larynx. It consists of a handle containing batteries that power a light and a set of interchangeable blades, which are either straight or curved.


Laryngoscope handle with an assortment of Macintosh blades (large adult, small adult, child, infant and newborn)











The Macintosh blade is the most widely used curved laryngoscope blade,[8] while the Miller blade[9] is the most popular style of straight blade.[10] Both Miller and Macintosh laryngoscope blades are available in sizes 0 (infant) through 4 (large adult).

Stylets

An intubating stylet is a malleable metal wire designed to be inserted into the endotracheal tube to make the tube conform better to the upper airway anatomy of the specific individual. This aid is commonly used with a difficult laryngoscopy.

Tracheal tube

The endotracheal tube has a fitting designed to be connected to a source of pressurized gas such as oxygen. At the other end is an orifice through which such gases are directed into the lungs and may also include a balloon (referred to as a cuff). The tip of the endotracheal tube is positioned above the carina (before the trachea divides to each lung) and sealed within the trachea so that the lungs can be ventilated equally.


Originally made from latex rubber,[28] most modern endotracheal tubes today are constructed of polyvinyl chloride. Tubes constructed of silicone rubber, wire-reinforced silicone rubber or stainless steel are also available for special applications. For human use, tubes range in size from 2 to 10.5 mm (0.1 to 0.4 in) in internal diameter. The size is chosen based on the patient's body size, with the smaller sizes being used for infants and children.

METHODS TO CONFIRM PLACEMENT

No single method for confirming tracheal tube placement has been shown to be 100% reliable. Accordingly, the use of multiple methods for confirmation of correct tube placement is now widely considered to be the standard of care.[32] Such methods include direct visualization as the tip of the tube passes through the glottis. With a properly positioned tracheal tube, equal bilateral breath sounds will be heard upon listening to the chest with a stethoscope, and no sound upon listening to the area over the stomach. Equal bilateral rise and fall of the chest wall will be evident with ventilatory excursions. A small amount of water vapor will also be evident within the lumen of the tube with each exhalation and there will be no gastric contents in the tracheal tube at any time.[31]

Ideally, at least one of the methods utilized for confirming tracheal tube placement will be a measuring instrument. Waveform capnography has emerged as the gold standard for the confirmation of tube placement within the trachea. Other methods relying on instruments include the use of a colorimetric end-tidal carbon dioxide detector, a self-inflating esophageal bulb, or an esophageal detection device.[33] The distal tip of a properly positioned tracheal tube will be located in the mid-trachea, roughly 2 cm (1 in) above the bifurcation of the carina; this can be confirmed by chest x-ray. If the tracheal tube is inserted too far into the trachea, the tip will often be located within the right main bronchus, because this bronchus has a less acute angle than the left.[34]

4 Ways to Strengthen Your Immune System

Hype about immune boosters can end up putting a real pinch your wallet. Here are tips you can bank on.

By Christopher Woolston

1. Go nuts for E. Immune cells can’t function without proper nutrition, says Simin Meydani, PhD, director of the USDA Human Nutrition Research Center at Tufts University. "In an outbreak, a deficiency of nutrients can be as dangerous as not washing your hands," she says. But many people don't get enough vitamin E, a proven immune enhancer, says Patricia Sheridan, PhD, at the University of North Carolina at Chapel Hill. You need at least 15 mg of E daily, she says, which you can get in a generous handful of almonds (7 mg of E per ounce). The elderly and people with weakened immune systems may need a supplement of 200 mg of E, Meydani believes.



Most people don't get enough vitamin E, a proven immune enhancer.


In her study of nursing home residents, supplementing with that amount cut the risk of colds and flu by about 20 percent. Don't take more, though: One highly publicized study suggested that high doses (400 mg per day or more) can increase the risk of death.

2. Don't stint on selenium. This trace mineral helps build immune system enzymes. Most people in the United States aren't deficient but could use a little extra to sharpen their immune systems, Sheridan says. She recommends about 55 micrograms, which you can get in a tuna sandwich.

3. Consider popping the "sunshine vitamin." Vitamin D is needed to produce certain germ-killing proteins (a recent study suggests that low levels raise the risk of respiratory infection by more than 35 percent). But many people fall short, says Michael Holick, MD, professor of medicine at Boston University. You can't get much vitamin D from food, so Holick recommends that adults supplement with 1,000 IU a day, plus a multivitamin containing another 400 IU.

4. Work out (but don’t burn out). Even a little exercise can wake up the immune system, says Thomas Lowder, PhD, at the University of Houston. (Exercise that wrecks you for days can actually make you more vulnerable, though.) In a 2006 study, women either exercised moderately five times a week or stretched once a week. By study's end, the exercisers were only one third as likely as the stretchers to be sniffling and sneezing. "Nobody can say for sure how much exercise it takes to improve the immune system," Lowder says. "But it's not much, and it happens very quickly."