The systematic review

The systematic review

What is it?

A systematic review¹ ( Chalmers, I. &Altman, D.G. (eds) (1995) Systematic Reviews. British Medical Journal Publishing Group, London) is a formalized and stringent process of combining the information from all relevant studies (both published and unpublished) of the same health condition; these studies are usually clinical trials (Topic 14) of the same or similar treatments but may be observational studies (Topics 15 and 16). Clearly, a systematic review is an integral part of evidence based medicine (EBM; Topic 37), which applies the results of the best available evidence, together with clinical expertise, to the care of patients. So important is its role in EBM, that it has become the focus of an international network of clinicians, methodologists and consumers who have formed the Cochrane Collaboration. They have created the Cochrane ControlledTrials Register, and publish continually updated systematic reviews in various forms (e.g. on CD ROM).

What does it achieve?

• Refinement and reduction - large quantities of information are refined and reduced to a manageable size.
• Efficiency -the systematic review is usually quicker and less costly to perform than a new study. It may prevent others embarking on unnecessary studies, and can shorten the time lag between medical developments and their implementation.
• Generalizability and consistency-results can often be generalized to a wider patient population in a broader setting than would be possible from a single study. Consistencies in the results from different studies can be assessed, and any inconsistencies determined.
• Reliability - the systematic review aims to reduce errors,
• and so tends to improve the reliability and accuracy of recommendations when compared with haphazard reviews or single studies.
• Power and precision- the quantitative systematic review (see meta-analysis) has greater power (Topic 18) to detect effects of interest and provides more precise estimates of them than a single study.

Meta-analysis

What is it?

A meta-analysis or overview is a particular type of systematic review that focuses on the numerical results. The main aim of a meta-analysis is to combine the results from individual studies to produce, if ppropriate, an estimate ofthe overall or average effect of interest (e.g. the relative risk, RR; Topic 15). The direction and magnitude of this average effect, together with a consideration of the associated confidence interval and hypothesis test result, can be used to make decisions about the therapy under investigation and the management of patients.

Statistical approach

• We decide on the effect of interest and, if the raw data are available, evaluate it for each study. However, in practice, we may have to extract these effects from published results. If the outcome in a clinical trial comparing two treatments is:
• numerical-the effect may be the difference in treatment means. A zero difference implies no treatment effect;
• binary (e.g. died1survived)-we consider the risks of the outcome (e.g. death) in the treatment groups. The effect may be the difference in risks or their ratio, the RR. If the difference in risks equals zero or RR = 1 then there is no treatment effect.
• Obtain an estimate of statistical heterogeneity and check for statistical homogeneity -we have statistical heterogeneity when there is considerable variation between the estimates of the effect of interest from the different studies. We can measure it, and perform a hypothesis test to investigate whether the individual estimates are compatible (i.e. homogeneous). If there is significant statistical heterogeneity, we should proceed cautiously, investigate the reasons for its presence and modify our approach accordingly.
• Estimate the average effect of interest (with a confidence interval), and perform the appropriate hypothesis test on the effect (e.g. that the true RR = 1)-you may come across the terms 'fixed-effects' and 'random-effects' models in this context. Although the underlying concepts are beyond the scope of this book, note that we generally use a fixed-effects model if there is no evidence of statistical heterogeneity, and a random-effects model otherwise.
• Interpret the results and present the findings-it is helpful to summarize the results from each trial (e.g. the sample size, baseline characteristics, effect of interest such as the RR, and related confidence intervals, CI) in a table (see Example). The most common graphical display is a forest plot (Fig. 38.1) in which the estimated effect (with CI) for each trial, and their average, are marked along the length of a vertical line which represents 'no treatment effect' (e.g. this line corresponds to the value 'one' if the effect is a RR). Initially, we examine whether the estimated effects from the different studies are on the same side of the
• line. Then we can use the CIS to judge whether the results are compatible (if the CIS overlap), to determine whether incompatible results can be explained by small sample sizes (if CIS are wide) and to assess the significance of the individual and overall effects (by observing whether the vertical line crosses some or all of the CIS).

Advantages and disadvantages

• As a meta-analysis is a particular form of systematic review, it offers all the advantages of the latter (see 'what does it achieve?'). In particular, a meta-analysis, because of its inflated sample size, is able to detect treatment effects with greater power and estimate these effects with greater precision than any single study. Its advantages, together with the introduction of meta-analysis software, have led meta-analyses to proliferate. However, improper use can lead to erroneous conclusions regarding treatment efficacy. The following principal problems should be thoroughly investigated and resolved before a meta-analysis is
• performed.
• Publication bias-the tendency to include in the analysis only the results from published papers; these favour statistically significant findings.
• Clinical heterogeneity-in which differences in the patient population, outcome measures, definition of variables, and/or duration of follow-up of the studies included in the analysis create problems of non-compatibility.
• Quality differences-the design and conduct of the studies may vary in their quality. Although giving more weight to the better studies is one solution to this dilemma, any weighting system can be criticized on the grounds that it is arbitrary.
• Dependence-the results from studies included in the analysis may not be independent, e.g. when results from a study are published on more than one occasion.

Submandibular Gland Anatomy

Submandibular Gland Anatomy

• within the submandibular triangle (inferior to mylohyoid muscle, superior to the digastrics)
• superficial layer of the deep cervical fascia envelops the gland and contains the marginal mandibular nerve
• hypoglossal nerve runs deep to the digastric tendon and medial to the deep layer of the deep cervical fascia
• facial artery arises from the external carotid artery and courses medial to the posterior digastric muscle then hooks over the muscle to enter the gland and exits into the facial notch of the inferior mandible
• lingual artery runs along the lateral aspect of the middle constrictors, deep to the digastrics, and anteriorly and medially to the hyoglossus
• Histological Cell Type: mixed cells (serous and mucinous)
• Wharton’s Duct: opens lateral to frenulum in the anterior portion of the floor of mouth, behind the incisors

Parotid Gland Anatomy

Parotid Gland Anatomy

• located between the ramus of the mandible and the external auditory canal and mastoid tip, overlies the masseter muscle (anteriorly) and sternocleidomastoid muscle (posteriorly)
• facial nerve divides the parotid gland artificially into deep and superficial lobes
• the superficial layer of the deep cervical fascia forms the parotid gland fascia which incompletely surrounds the gland
• Histological Cell Type: basophilic, serous cells
• Stylomandibular Ligament: formed by the fascial envelope between the styloid process and the mandible, separates the parotid gland from the submandibular gland
• Stenson’s Duct: passes over masseter, through buccinator muscle, and opens opposite to the second upper molar (follows along plane from external auditory canal to columella and buccal branch of CN VII)



Venous Drainage
• superficial temporal vein + maxillary vein ➝ retromandibular vein
• retromandibular vein ➝ passes deep to the facial nerve ➝ anterior and posterior branches
• anterior retromandibular vein + facial vein ➝ common facial vein ➝ internal jugular vein
• posterior retromandibular vein + posterior auricular vein (over SCM) ➝ external jugular vein

Tracheotomy

---

---

Definition

A tracheotomy is a surgical procedure that opens up the windpipe (trachea). It is performed in emergency situations, in the operating room , or at bedside of critically ill patients. The term tracheostomy is sometimes used interchangeably with tracheotomy. Strictly speaking, however, tracheostomy usually refers to the opening itself while a tracheotomy is the actual operation.

Purpose

A tracheotomy is performed if enough air is not getting to the lungs, if the person cannot breathe without help, or is having problems with mucus and other secretions getting into the windpipe because of difficulty swallowing. There are many reasons why air cannot get to the lungs. The windpipe may be blocked by a swelling; by a severe injury to the neck, nose, or mouth; by a large foreign object; by paralysis of the throat muscles; or by a tumor. The patient may be in a coma, or need a ventilator to pump air into the lungs for a long period of time.

Demographics

Emergency tracheotomies are performed as needed in any person requiring one.

Description

Emergency tracheotomy

There are two different procedures that are called tracheotomies. The first is done only in emergency situations and can be performed quite rapidly. The emergency room physician or surgeon makes a cut in a thin part of the voice box (larynx) called the cricothyroid membrane. A tube is inserted and connected to an oxygen bag. This emergency procedure is sometimes called a cricothyroidotomy .

Surgical tracheotomy

The second type of tracheotomy takes more time and is usually done in an operating room. The surgeon first makes a cut (incision) in the skin of the neck that lies over the trachea. This incision is in the lower part of the neck between the Adam's apple and top of the breastbone. The neck muscles are separated and the thyroid gland, which overlies the trachea, is usually cut down the middle. The surgeon identifies the rings of cartilage that make up the trachea and cuts into the tough walls. A metal or plastic tube, called a tracheotomy tube, is inserted through the opening. This tube acts like a windpipe and allows the person to breathe. Oxygen or a mechanical ventilator may be hooked up to the tube to bring oxygen to the lungs. A dressing is placed around the opening. Tape or stitches (sutures) are used to hold the tube in place.

After a nonemergency tracheotomy, the patient usually stays in the hospital for three to five days, unless there is a complicating condition. It takes about two weeks to recover fully from the surgery.

Diagnosis/Preparation

Emergency tracheotomy

In the emergency tracheotomy, there is no time to explain the procedure or the need for it to the patient. The patient is placed on his or her back with face upward (supine), with a rolled-up towel between the shoulders. This positioning of the patient makes it easier for the doctor to feel and see the structures in the throat. A local anesthetic is injected across the cricothyroid membrane.

Nonemergency tracheotomy

In a nonemergency tracheotomy, there is time for the doctor to discuss the surgery with the patient, to explain what will happen and why it is needed. The patient

For a tracheotomy, an incision is made in the skin just above the sternal notch (A). Just below the thyroid, the membrane covering the trachea is divided (B), and the trachea itself is cut (C). A cross incision is made to enlarge the opening (D), and a tracheostomy tube may be put in place (E). (

Illustration by GGS Inc.

)

is then put under general anesthesia. The neck area and chest are then disinfected and surgical drapes are placed over the area, setting up a sterile surgical field.

Aftercare

Postoperative care

A chest x ray is often taken, especially in children, to check whether the tube has become displaced or if complications have occurred. The doctor may prescribe antibiotics to reduce the risk of infection. If the patient can breathe without a ventilator, the room is humidified; otherwise, if the tracheotomy tube is to remain in place, the air entering the tube from a ventilator is humidified. During the hospital stay, the patient and his or her family members will learn how to care for the tracheotomy tube, including suctioning and clearing it. Secretions are removed by passing a smaller tube (catheter) into the tracheotomy tube.

It takes most patients several days to adjust to breathing through the tracheotomy tube. At first, it will be hard even to make sounds. If the tube allows some air to escape and pass over the vocal cords, then the patient may be able to speak by holding a finger over the tube. Special tracheostomy tubes are also available that facilitate speech.

The tube will be removed if the tracheotomy is temporary. Then the wound will heal quickly and only a small scar may remain. If the tracheotomy is permanent, the hole stays open and, if it is no longer needed, it will be surgically closed.

Home care

After the patient is discharged, he or she will need help at home to manage the tracheotomy tube. Warm compresses can be used to relieve pain at the incision site. The patient is advised to keep the area dry. It is recommended that the patient wear a loose scarf over the opening when going outside. He or she should also avoid contact with water, food particles, and powdery substances that could enter the opening and cause serious breathing problems. The doctor may prescribe pain medication and antibiotics to minimize the risk of infections. If the tube is to be kept in place permanently, the patient can be referred to a speech therapist in order to learn to speak with the tube in place. The tracheotomy tube may be replaced four to 10 days after surgery.

Patients are encouraged to go about most of their normal activities once they leave the hospital. Vigorous activity is restricted for about six weeks. If the tracheotomy is permanent, further surgery may be needed to widen the opening, which narrows with time.

Risks

Immediate risks

There are several short-term risks associated with tracheotomies. Severe bleeding is one possible complication. The voice box or esophagus may be damaged during surgery. Air may become trapped in the surrounding tissues or the lung may collapse. The tracheotomy tube can be blocked by blood clots, mucus, or the pressure of the airway walls. Blockages can be prevented by suctioning, humidifying the air, and selecting the appropriate tracheotomy tube. Serious infections are rare.

Long-term risks

Over time, other complications may develop following a tracheotomy. The windpipe itself may become damaged for a number of reasons, including pressure from the tube, infectious bacteria that forms scar tissue, or friction from a tube that moves too much. Sometimes the opening does not close on its own after the tube is removed. This risk is higher in tracheotomies with tubes remaining in place for 16 weeks or longer. In these cases, the wound is surgically closed. Increased secretions may occur in patients with tracheostomies, which require more frequent suctioning.

High-risk groups

The risks associated with tracheotomies are higher in the following groups of patients:

• children, especially newborns and infants
• smokers
• alcoholics
• obese adults
• persons over 60
• persons with chronic diseases or respiratory infections
• persons taking muscle relaxants , sleeping medications, tranquilizers, or cortisone

Normal results

Normal results include uncomplicated healing of the incision and successful maintenance of long-term tube placement.

Morbidity and mortality rates

The overall risk of death from a tracheotomy is less than 5%.

Alternatives

For most patients, there is no alternative to emergency tracheotomy. Some patients with pre-existing neuromuscular disease (such as ALS or muscular dystrophy) can be sucessfully managed with emergency noninvasive ventilation via a face mask, rather than with tracheotomy. Patients who receive nonemergency tracheotomy in preparation for mechanical ventilation may often be managed instead with noninvasive ventilation, with proper planning and education on the part of the patient, caregiver, and medical staff.

Resources

BOOKS

Bach, John R. Noninvasive Mechanical Ventilation. NJ: Hanley and Belfus, 2002.

Fagan, Johannes J., et al. Tracheotomy. Alexandria, VA: American Academy of Otolaryngology-Head and Neck Surgery Foundation, Inc., 1997.

"Neck Surgery." In The Surgery Book: An Illustrated Guide to 73 of the Most Common Operations , ed. Robert M. Younson, et al. New York: St. Martin's Press, 1993.

Schantz, Nancy V. "Emergency Cricothyroidotomy and Tracheostomy." In Procedures for the Primary Care Physician , ed. John Pfenninger and Grant Fowler. New York: Mosby, 1994.

Read more: Tracheotomy - procedure, blood, tube, pain, complications, adults, time, infection, operation, medication, risk, children, Definition, Purpose, Demographics, Description, Diagnosis/Preparation http://www.surgeryencyclopedia.com/St-Wr/Tracheotomy.html#ixzz0karjE5qB

REF: http://www.surgeryencyclopedia.com

Endotracheal intubation

---

---

Definition

Endotracheal intubation is the placement of a tube into the trachea (windpipe) in order to maintain an open airway in patients who are unconscious or unable to breathe on their own. Oxygen, anesthetics, or other gaseous medications can be delivered through the tube.

Purpose

Specifically, endotracheal intubation is used for the following conditions:

• respiratory arrest
• respiratory failure
• airway obstruction
• need for prolonged ventilatory support
• Class III or IV hemorrhage with poor perfusion
• severe flail chest or pulmonary contusion
• multiple trauma, head injury and abnormal mental status
• inhalation injury with erythema/edema of the vocal cords
• protection from aspiration

Description

To begin the procedure, 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. 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. 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. 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. Finally, the cuff is inflated to provide a minimal leak when the bag is squeezed. Using a stethoscope , the anesthesiologist listens for breathing sounds to ensure correct placement of the tube.

Preparation

For endotracheal intubation, the patient is placed on the operating table lying on the back with a pillow under the head. The anesthesiologist wears gloves, a gown and goggles. General anesthesia is administered to the patient before starting intubation.

Risks

The anesthesiologist should evaluate and follow the patient for potential complications that may include edema; bleeding; tracheal and esophageal perforation; pneumothorax (collapsed lung); and aspiration. The patient should be advised of the potential signs and symptoms associated with life-threatening complications of airway problems. These signs and symptoms include but are not limited to sore throat, pain or swelling of the face and neck, chest pain, subcutaneous emphysema, and difficulty swallowing.

Normal results

The endotracheal tube inserted during the procedure maintains an open passage through the upper airway and allows air to pass freely to and from the lungs in order to ventilate them.

Alternatives

Alternatives to endotracheal intubation include:

• Esophageal tracheal combitube (ETC). The ETC is a double-lumen tube, combining the function of an esophageal obturator airway and a conventional endotracheal airway. The esophageal lumen has an open upper end, perforations at the pharyngeal level, and a closed distal end. The tracheal lumen has open ends. The lumens are separated by a wall and each is linked via a short tube with a connector. An oropharyngeal balloon serves to seal the oral and nasal cavities after
  

  The doctor inserts the laryngoscope into the patient's mouth, advancing through the trachea to the vocal cords (A). An endotracheal tube is inserted into the airway (B). The balloon cuff is inflated, and the laryngoscope is removed (C). (

  Illustration by GGS Inc.

  )
  insertion. At the lower end, a second cuff serves to seal either the trachea or esophagus.
• Laryngeal mask airway (LMA). The LMA consists of an inflatable silicone ring attached diagonally to a flexible tube. The ring forms an oval cushion that fills the space around and behind the larynx. It achieves a low-pressure seal between the tube and the trachea without insertion into the larynx.
• Tracheostomy. A tracheostomy is a surgically created opening in the neck that allows direct access to the trachea. It is kept open with a tracheostomy tube. A tracheostomy is performed when it is not possible to intubate the patient.

See also Anesthesia evaluation .

Resources

BOOKS

Finucane, B. T., and A. H. Santora. Principles of Airway Management. New York: Springer Verlag, 2003.

Roberts, J. T. Fundamentals of Tracheal Intubation. New York: Grune & Stratton, 1983.

Stewart, C. E. Advanced Airway Management. St. Louis: Quality Medical Publishing, 2002.

Read more: Endotracheal Intubation - procedure, tube, pain, complications, Definition, Purpose, Description, Preparation, Risks, Normal results, Alternatives http://www.surgeryencyclopedia.com/Ce-Fi/Endotracheal-Intubation.html#ixzz0karC1vXC

REF: http://www.surgeryencyclopedia.com

Cricothyroidotomy

---

---

Definition

Cricothyroidotomy is usually regarded as an emergency surgical procedure in which a surgeon or other trained person cuts a hole through a membrane in the patient's neck into the windpipe in order to allow air into the lungs. Cricothyroidotomy is a subtype of surgical procedure known as a tracheotomy ; in some situations, it is considered an elective alternative to other types of tracheotomy.

Purpose

The primary purpose of a cricothyroidotomy is to provide an emergency breathing passage for a patient whose airway is closed by traumatic injury to the neck; by burn inhalation injuries; by closing of the airway due to an allergic reaction to bee or wasp stings; or by unconsciousness. It may also be performed in some seriously ill patients with structural abnormalities in the neck. Some surgeons consider a cricothyroidotomy to be preferable to a standard tracheotomy in treating patients in an intensive care unit .

Demographics

The demographics of cricothyroidotomies are difficult to establish because the procedure is relatively uncommon in the general population, even in emergency situations. In the emergency room, the incidence varied between 1.7% and 2.7%. A study found that nine of a group of 1,560 patients admitted for blunt or penetrating injuries of the neck required emergency cricothyroidotomies, or about 0.5%.

Another study found that the most important single cause of injuries requiring emergency cricothyroidotomy was traffic accidents (51%), followed by gunshot and knife wounds (29%); falls (5%); and criminal assault (5%).

Most cricothyroidotomies are performed on adolescent and young adult males, because this group accounts for the majority of cases of neck trauma in the United States. It is estimated that injuries to the neck account for 5–10% of all serious traumatic injuries.

Description

There are two basic types of cricothyroidotomy: needle cricothyroidotomy and surgical cricothyroidotomy.

Needle cricothyroidotomy

In a needle cricothyroidotomy, a syringe with a needle attached is used to make a puncture hole through the cricothyroid membrane that overlies the trachea. After the needle has reached the trachea, a catheter is passed over the needle into the windpipe and attached to a bag-valve device.

To perform a cricothyroidotomy, the surgeon makes an incision into the cricoid cartilage of the throat (B). The incision is held open while an endotracheal tube is inserted (C). The tube is secured in the trachea to maintain an airway for the patient (D). ( Illustration by GGS Inc. )

Surgical cricothyroidotomy

In a surgical cricothyroidotomy, the doctor or other emergency worker makes an incision through the cricothyroid membrane into the trachea in order to insert a piece of tubing for ventilating the patient.

Diagnosis/Preparation

The primary concerns in emergency medical treatment are sometimes known as the ABCs: Airway patency (openness), Breathing, and Circulation. Keeping the airway patent is critical to an injured person's survival. The signs of a blocked airway in people are obvious, including a bluish complexion (cyanosis); noisy breathing, unusual breath sounds, or choking; emotional agitation or panic; and often loss of consciousness.

In an emergency situation, the following are considered reasons for performing a cricothyroidotomy first rather than attempting to open or clear the patient's airway by other methods:

• Major injuries to the face or jaw, such as multiple fractures of the jawbone or severe fractures of the patient's midface. In many cases of facial injury, the airway is blocked by broken teeth or fragments of bone from the jaw and cheekbones.
• Burns in or around the mouth.
• A neurological disorder or damage that has caused the patient's teeth to clamp shut.
• Fractured larynx. Fractures of the larynx most commonly result from automobile or motorcycle accidents, but also occur in cases of strangulation or attempted suicide by hanging.
• Larynx swollen shut by allergic reaction to bee or wasp venom.

Preparation

The first steps in preparation are the same for needle and surgical cricothyroidotomies. The patient is positioned lying on the back with a towel under the shoulders and the neck stretched backward (hyperextended). If the patient is conscious, he or she is given a local anesthetic. The doctor then palpates, or feels, the patient's throat for the thyroid cartilage, or Adam's apple. This piece of cartilage is an anatomical landmark for this procedure, which means that it is a structure that is relatively easy to identify and serves as a reference point for other structures. In men, the Adam's apple is easy to find by running the finger down the center of the neck. In women, however, the thyroid cartilage is less prominent. Below the thyroid cartilage is a softer area about the width of a finger; this is the cricothyroid membrane, which is a piece of tissue lying between the thyroid cartilage above it and the cricoid cartilage below it.

When the doctor has located the cricothyroid membrane, he or she will scrub the skin over it with a povidone-iodine solution to prevent infection.

Needle cricothyroidotomy

In a needle cricothyroidotomy, the doctor uses a 12- or 14-gauge catheter and needle assembly. The needle is advanced through the cricothyroid cartilage at a 45-degree angle until the trachea is reached. When the doctor is able to withdraw air through the syringe, he or she knows that the catheter is in the correct spot. The catheter is then pushed forward over the needle, which is then removed. An endotracheal tube connector is then fitted onto the end of the catheter and connected to a bag-valve unit with an oxygen reservoir.

A needle cricothyroidotomy will supply the patient with enough oxygen for about 40–45 minutes; it is a time-limited technique because it does not allow the efficient escape of carbon dioxide from the bloodstream. It will, however, help to ventilate the patient until he or she can be taken to a hospital or trauma center.

Needle cricothyroidotomy is the only form of this procedure that can be done in children under 12 years of age. The reason for this restriction is that the upper part of the trachea is not fully developed in children, and a surgical incision through the cricothyroid membrane increases the risk of the child's developing subglottic stenosis, which is a condition in which the trachea is abnormally narrow below the level of the vocal cords due to an overgrowth of soft tissue. It is often seen in children who were intubated as infants.

Surgical cricothyroidotomy

In a surgical cricothyroidotomy, the doctor steadies the patient's thyroid cartilage with one hand and makes a horizontal (transverse) incision across the cricothyroid membrane. The incision is deepened until the airway is reached. The doctor then rotates the edge of the scalpel 90° in order to open the incision to receive an endotracheal or tracheotomy tube. A hemostat or surgical clamp may be used to hold the incision open while the doctor prepares to insert the tube through the opening into the trachea. After checking the tube to make certain that it is in the proper location, the doctor tapes it in place. If necessary, the doctor may use suction to clear the patient's airway.

In some emergency situations, the doctor or other medical professional may not have an antiseptic available to cleanse the skin over the patient's throat, and may have to use any sharp-edged implement that is handy to make the incision. Emergency cricothyroidotomies have been performed with scissors, hunting or pocketknives, razor blades, broken glass, and the jagged edges of a lid from a tin can. The airway has been held open with such objects as paper clips, nail clippers, the plastic barrel from a ballpoint pen, and a piece of plastic straw from a sports water bottle.

Aftercare

Needle cricothyroidotomy

A needle cricothyroidotomy must be replaced by a formal surgical tracheotomy or other means of ventilating the patient within 45 minutes.

Surgical cricothyroidotomy

A surgical cricothyroidotomy can be left in place for about 24 hours, but should be replaced within that time period by a formal tracheotomy performed in a hospital operating room .

Other aspects of aftercare depend on the cause of the airway blockage and the nature of the patient's injuries. The head and neck contain major blood vessels, a large portion of the central nervous system, the organs of sight, smell, hearing, and taste, and the central airway—all within a relatively small area. Injuries to the face and neck often require treatment by specialists in neurology, trauma surgery, otolaryngology, ophthalmology, and plastic surgery as well as by specialists in emergency medicine.

Risks

Needle cricothyroidotomy

The risks of a needle cricothyroidotomy include:

• external scar from needle puncture
• bleeding
• accidental perforation of the esophagus
• hypercarbia (overly high levels of carbon dioxide in the blood)

Surgical cricothyroidotomy

The risks of surgical cricothyroidotomy include:

• large visible external scar from the incision
• subglottic stenosis
• bleeding
• accidental perforation of the esophagus
• fracture of the larynx
• pneumothorax, which is a condition in which air has entered the space around the lungs
• damage to the vocal cords resulting in hoarseness or a changed voice

Normal results

Needle cricothyroidotomy

Normal results for a needle cricothyroidotomy would be adequate ventilation of a patient with a blocked airway for a brief period of time of about 45 minutes.

Surgical cricothyroidotomy

Normal results of a surgical cricothyroidotomy would be adequate ventilation in emergency circumstances of a patient with a blocked airway for a period of about 24 hours.

Morbidity and mortality rates

In general, cricothyroiditomy has a very low mortality rate, even when performed outside a hospital. By contrast, the mortality rate for patients who lose airway patency is 33%. Overall, emergency cricothyroidotomy is considered an effective way to create an emergency surgical airway with low overall morbidity.

Alternatives

Cricothyroidotomy is generally considered a procedure of last resort, to be performed when other ways of opening the patient's airway have failed or are unavailable. It is frequently done if endotracheal intubation has been attempted and failed, or if intubation cannot be performed due to the nature of the patient's injuries. Endotracheal intubation is a procedure in which a breathing tube is introduced directly into the trachea through the patient's mouth or nose with the help of a laryngoscope. It is most commonly done during general anesthesia, but can also be performed to help the patient breathe.

One alternative to cricothyroidotomy is a technique known as transtracheal jet ventilation (TTJV). In TTJV, a syringe is used to introduce a catheter through the patient's cricothyroid membrane. The catheter is connected to a high-pressure oxygen supply. In hospital settings, TTJV has about the same rate of complications as a surgical cricothyroidotomy. Its disadvantages are that it cannot be used outside a hospital setting and it takes longer to perform. A surgical cricothyroidotomy can be performed in 30 seconds to two minutes; TTJV takes twice to three times as long to perform.

See also Endotracheal intubation ; Tracheotomy .

Resources

BOOKS

Gomella, Leonard G., and Alan T. Lefor. Surgery On Call, 3rd ed. New York: McGraw-Hill/Appleton & Lange, 2001.

Read more: Cricothyroidotomy - procedure, blood, tube, complications, time, infection, types, risk, children, rate, Definition, Purpose, Demographics, Description, Diagnosis/Preparation, Aftercare, Risks http://www.surgeryencyclopedia.com/Ce-Fi/Cricothyroidotomy.html#ixzz0kaqJpbzZ



REF:
http://www.surgeryencyclopedia.com