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What is a mechanical ventilator? How are mechanical ventilators classified? Why are there so many different ways to ventilate a patient? What is the difference between PEEP and CPAP? What do I need to know about volume-controlled ventilators? What is volume assist-control ventilation? What is (synchronized) intermittent mandatory ventilation (IMV / SIMV)? What is the difference between constant, decelerating and sinusoidal flow waveforms? How do I set the peak flow (PF)? What is pressure controlled ventilation (PCV)? What is Pressure Support and How does it work? What is the Plateau Pressure? What causes dysynchrony? Why do some physicians say that you should not mix volume with pressure? What is the difference between Inverse Ratio Ventilation (IRV) and Airway Pressure Release Ventilation (ARPV), Bilevel and Proportional Assist Ventilation? How do I analyze ventilator waveforms? Positive-pressure ventilation means that airway pressure is applied at the patient's airway through an endotracheal or tracheostomy tube. The positive nature of the pressure causes the gas to flow into the lungs until the ventilator breath is terminated. As the airway pressure drops to zero, elastic recoil of the chest accomplishes passive exhalation by pushing the tidal volume out. Classifications of Positive-Pressure Ventilators Modern ventilators are classified by their method of cycling from the inspiratory phase to the expiratory phase. That is, they are named after that parameter that signals the termination of the positive-pressure inspiration cycle of the machine. The signal to terminate the inspiratory activity of the machine is either a preset volume (for a volume-cycled ventilator), a preset pressure limit (for a pressure-cycled ventilator), or a preset time factor (for a time-cycled ventilator). Volume-cycled ventilation is the most common form of ventilator cycling used in adult medicine because it provides a consistent breath-to-breath tidal volume. Termination of the delivered breath is signaled when a set volume leaves the ventilator. Indications for Mechanical Ventilation Many factors affect the decision to begin mechanical ventilation. Because no mode of mechanical ventilation can cure a disease process, the patient should have a correctable underlying problem that can be resolved with the support of mechanical ventilation. This intervention should not be started without thoughtful consideration because intubation and positive-pressure ventilation are not without potentially harmful effects. Mechanical ventilation is indicated when the patient's spontaneous ventilation is inadequate to sustain life. In addition, it is indicated as a measure to control ventilation in critically ill patients and as prophylaxis for impending collapse of other physiologic functions. Physiologic indications include respiratory or mechanical insufficiency and ineffective gas exchange. Common indications for mechanical ventilation include the following: * Bradypnea or apnea with respiratory arrest * Acute lung injury and the acute respiratory distress syndrome * Tachypnea (respiratory rate >30 breaths per minute) * Vital capacity less than 15 mL/kg * Minute ventilation greater than 10 L/min * Arterial partial pressure of oxygen (PaO2) with a supplemental fraction of inspired oxygen (FIO2) of less than 55 mm Hg * Alveolar-arterial gradient of oxygen tension (A-a DO2) with 100% oxygenation of greater than 450 mm Hg * Clinical deterioration * Respiratory muscle fatigue * Obtundation or coma * Hypotension * Acute partial pressure of carbon dioxide (PaCO2) greater than 50 mm Hg with an arterial pH less than 7.25 * Neuromuscular disease The trend of these values should influence clinical judgment. Increasing severity of illness should prompt the clinician to consider starting mechanical ventilation. Initial Ventilator Settings Mode of ventilation After deciding to start positive-pressure ventilation with a volume-cycled ventilator, the clinician must now select the safest initial mode of machine operation. In most circumstances, the initial mode of ventilation should be the assist-control mode, in which a tidal volume and rate are preset and guaranteed. The patient can affect the frequency and timing of the breaths. If the patient makes an inspiratory effort, the ventilator senses a decrease in the circuit pressure and delivers the preset tidal volume. In this way, the patient can dictate a comfortable respiratory pattern and may trigger additional machine-assisted breaths above the set rate. If the patient does not initiate inspiration, the ventilator automatically delivers the preset rate and tidal volume, ensuring minimum minute ventilation. In the assist-control mode, the work of breathing is reduced to the amount of inspiration needed to trigger the inspiratory cycle of the machine. This trigger is adjusted by setting the sensitivity of the machine to the degree of pressure decrease desired in the circuit (see Media File 2). The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for assist-control ventilation. The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for assist-control ventilation. Assist-control differs from controlled ventilation because the patient can trigger the ventilator to deliver a breath and, thereby, adjust their minute ventilation. In controlled ventilation, the patient receives only breaths initiated by the ventilator at the preset rate (see Media File 3). The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for controlled ventilation. The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for controlled ventilation. Although the work of breathing is not eliminated, this mode gives the respiratory muscles the greatest amount of rest because the patient needs only to create enough negative pressure to trigger the machine. An added advantage is that the patient can achieve the required minute ventilation by triggering additional breaths above the set back-up rate. In most cases, a minute ventilation that provides a reasonable pH based on the respiratory rate is determined by the patient's chemoreceptors and stretch receptors. The respiratory center in the central nervous system receives input from the chemical receptors (arterial blood gas tensions) and neural pathways that sense the mechanical work of breathing (mechanoreceptors). The respiratory rate and respiratory pattern are the result of input from these chemoreceptors and mechanical receptors, which allow the respiratory center to regulate gas exchange. In the assist-control mode, this process is accomplished with the minimum work of breathing. A second possible advantage of this mode of mechanical ventilation is that cycling the ventilator into the inspiratory phase maintains normal ventilatory activity and, therefore, prevents atrophy of the respiratory muscles. A potential disadvantage of the assist-control mode is respiratory alkalosis in a small subset of patients whose respiratory drive supersedes the chemoreceptors and mechanical receptors. Patients with a potential for alveolar hyperventilation and hypocapnia in the assist-control mode include those with end-stage liver disease, those in the hyperventilatory stage of sepsis, and those with head trauma. These conditions are typically identified with the first arterial blood gas results, and the assist-control mode of ventilation can then be changed to an alternate mode. Another possible disadvantage is the potential for serial preset positive-pressure breathes to retard venous return to the right side of heart and to affect global cardiac output. Nevertheless, the assist-control mode may be the safest initial choice for mechanical ventilation. It may be switched to another option if hypotension or hypocarbia are evident from the first arterial blood gas results. Tidal volume and rate For a patient without preexisting lung disease, the tidal volume and rate are traditionally selected by using the 12-12 rule. A tidal volume of 12 mL for each kilogram of lean body weight is programmed to be delivered 12 times a minute in the assist-control mode. For patients with chronic obstructive pulmonary disease (COPD), the tidal volume and rate are slightly reduced to the 10-10 rule to prevent overinflation and hyperventilation. A tidal volume of 10 mL/kg lean body weight is delivered 10 times a minute in the assist-control mode. In acute respiratory distress syndrome (ARDS), the lungs may function best and volutrauma (see Complications of Mechanical Ventilation) is minimized with low tidal volumes of 6-8 mL/kg. Tidal volumes are preset at 6-8 mL/kg of lean body weight in the assist-control mode. This ventilatory strategy is called lung-protective ventilation. These lowered volumes may lead to slight hypercarbia. An elevated PCO2 is typically recognized and accepted without correction, leading to the term permissive hypercapnia. However, the degree of respiratory acidosis allowable is a pH not less than 7.25. The respiratory rate of the ventilator may need to be adjusted upward to increase the minute ventilation lost by using smaller tidal volumes. Double-checking the selected tidal volume After a tidal volume is selected, the peak airway pressure necessary to deliver a single breath should be determined. As the tidal volume increases, so does the pressure required to force that volume into the lung. Persistent breath-to-breath peak pressures greater than 45 cm water are a risk factor for barotrauma (see Complications of Mechanical Ventilation). The tidal volume suggested by the above rules may need to be decreased in some patients to keep the peak airway pressure less than 45 cm water (see Media File 4). The components of mechanical ventilation inflatio... The components of mechanical ventilation inflation pressures. Paw is airway pressure, PIP is peak airway pressure, Pplat is plateau pressure. The components of mechanical ventilation inflatio... The components of mechanical ventilation inflation pressures. Paw is airway pressure, PIP is peak airway pressure, Pplat is plateau pressure. Some researchers have suggested that plateau pressures should be monitored as a means to prevent barotrauma in the patient with ARDS. Plateau pressures are measured at the end of the inspiratory phase of a ventilator-cycled tidal volume. The ventilator is programmed not to allow expiratory airflow at the end of the inspiration for a set time, typically half a second. The pressure measured to maintain this lack of expiratory airflow is the plateau pressure. Barotrauma is minimized when the plateau pressure is maintained at less than 30-35 cm water (see Media File 4). Monitoring the peak and plateau pressures allows physicians to make clinical judgments on the progress of their patient (see Media File 5). The effects of increased airway resistance (A) an... The effects of increased airway resistance (A) and decreased respiratory system compliance on the pressure-time waveform. The effects of increased airway resistance (A) an... The effects of increased airway resistance (A) and decreased respiratory system compliance on the pressure-time waveform. Sighs Because a spontaneously breathing individual typically sighs 6-8 times each hour to prevent microatelectasis, some investigators once recommended that periodic machine breaths that were 1.5-2 times the preset tidal volume be given 6-8 times per hour. However, the peak pressure often needed to deliver such a volume was high enough to predispose the patient to barotrauma. At present, accounting for sighs is not recommended if the patient is receiving tidal volumes of 10-12 mL/kg or if the patient requires positive end-expiratory pressure (PEEP). When a low tidal volume is used, sighs are preset at 1.5-2 times the tidal volume and delivered 6-8 times an hour if the peak and plateau pressures are within acceptable limits. Initial FIO2 The highest priority at the start of mechanical ventilation is providing effective oxygenation. For the patient's safety after intubation, the FIO2 should always be set at 100% until adequate arterial oxygenation is documented. A short period with an FIO2 of 100% is not dangerous to the patient receiving mechanical ventilation and offers the clinician several advantages. First, an FIO2 of 100% protects the patient against hypoxemia if unrecognized problems occur as a result of the intubation procedure. Second, using the PaO2 measured with an FIO2 of 100%, the clinician can easily calculate the next desired FIO2 and quickly estimate the shunt fraction. The degree of shunt with 100% FIO2 can be estimated by applying this general rule: The measured PaO2 is subtracted from 700 mm Hg. For each difference of 100 mm Hg, the shunt is 5%. A shunt of 25% should prompt the clinician to consider the use of PEEP. Inadequate oxygenation despite the administration of 100% oxygen should lead to a search for complications of endotracheal intubation (eg, mainstem intubation) or positive-pressure breathing (pneumothorax). If such complications are not present, PEEP is needed to treat the intrapulmonary shunt pathology. Because only a few disease processes can create an intrapulmonary shunt, a clinically significant estimated shunt should narrow the potential source of hypoxemia to the following conditions: * Alveolar collapse - Major atelectasis * Alveolar filling with something other than gas - Lobar pneumonia * Water and protein - ARDS * Water - Congestive heart failure * Blood - Hemorrhage Positive end-expiratory pressure PEEP is a mode of therapy used in conjunction with mechanical ventilation. At the end of mechanical or spontaneous exhalation, PEEP maintains the patient's airway pressure above the atmospheric level by exerting pressure that opposes passive emptying of the lung. This pressure is typically achieved by maintaining a positive pressure flow at the end of exhalation. This pressure is measured in centimeters of water. PEEP therapy can be effective when used in patients with a diffuse lung disease that results in an acute decrease in functional residual capacity (FRC), which is the volume of gas that remains in the lung at the end of a normal expiration. FRC is determined by primarily the elastic characteristics of the lung and chest wall. In many pulmonary diseases, FRC is reduced because of the collapse of the unstable alveoli. This reduction in lung volume decreases the surface area available for gas exchange and results in intrapulmonary shunting (unoxygenated blood returning to the left side of the heart). If FRC is not restored, a high concentration of inspired oxygen may be required to maintain the arterial oxygen content of the blood in an acceptable range. Applying PEEP increases alveolar pressure and alveolar volume. The increased lung volume increases the surface area by reopening and stabilizing collapsed or unstable alveoli. This splinting, or propping open, of the alveoli with positive pressure improves the ventilation-perfusion match, reducing the shunt effect. After a true shunt is modified to a ventilation-perfusion mismatch with PEEP, lowered concentrations of oxygen can be used to maintain an adequate PaO2. PEEP therapy may also be effective in improving lung compliance. When FRC and lung compliance are decreased, additional energy and volume are required to inflate the lung. By applying PEEP, the lung volume at the end of exhalation is increased. The already partially inflated lung requires less volume and energy than before for full inflation. When used to treat patients with a diffuse lung disease, PEEP should improve compliance, decrease dead space, and decrease the intrapulmonary shunt effect. The most important benefit of the use of PEEP is that it enables the patient to maintain an adequate PaO2 at a low and safe concentration of oxygen (<60%), reducing the risk of oxygen toxicity (see Complications of Mechanical Ventilation). Because PEEP is not a benign mode of therapy and because it can lead to serious hemodynamic consequences, the ventilator operator should have a definite indication to use it. The addition of external PEEP is typically justified when a PaO2 of 60 mm Hg cannot be achieved with an FIO2 of 60% or if the estimated initial shunt fraction is greater than 25%. No evidence supports adding external PEEP during initial setup of the ventilator to satisfy misguided attempts to supply prophylactic PEEP or physiologic PEEP. Many clinicians use the least-PEEP philosophy, which recommends using the lowest positive pressure that provides an adequate PaO2 with a safe FIO2. Another manner of selecting the optimal PEEP is based on identifying the low inflection point on the volume-pressure curve generated breath to breath by using modern mechanical ventilators. PEEP should be set 1-2 cm of water pressure above this measured low inflection point to obtain the optimal PEEP (see Media File 6). Because PEEP basically resets the baseline of the pressure-volume curve, the peak and plateau pressures will be affected. The clinician should pay close attention to the status of these pressure measurements (see Media File 6). Determination of the lower inflection point to es... Determination of the lower inflection point to estimate the best (optimal) positive end-expiratory pressure (PEEP) from the pressure-volume hysteresis curve. Determination of the lower inflection point to es... Determination of the lower inflection point to estimate the best (optimal) positive end-expiratory pressure (PEEP) from the pressure-volume hysteresis curve. Summary of initial ventilator setup Initial settings for ventilation may be summarized as follows: * Assist-control mode * Tidal volume set depending on lung status o Normal = 12 mL/kg ideal body weight o COPD = 10 mL/kg ideal body weight o ARDS = 6-8 mL/kg ideal body weight * Rate of 10-12 breaths per minute * FIO2 of 100% * Sighs rarely needed * PEEP only as indicated after first arterial blood gas determination, ie, shunt greater than 25% * Inability to oxygenate with an FIO2 less than 60% Adjustments and Withdrawal Prone positioning Prone positioning has been used in patients with ARDS and severe hypoxia and improves FRC, postural drainage of secretions, and ventilation-perfusion matching. Moving the intubated patient from the supine position to the prone position requires a coordinated effort from the nursing staff, respiratory therapists, and physicians to prevent inadvertent extubation or loss of various lines and tubes. Prone positioning may improve oxygenation in greater than 50% of such patients, but no survival benefit has been documented. Sedation, protocols, and prophylaxis Most patients receiving mechanical ventilation need sedation given by means of continuous infusion or scheduled dosing to help with anxiety and psychological stress inherent with this intervention. Daily interruption of sedation, when clinically allowable, decreases the number of days of mechanical ventilation. This sedation holiday helps the patient become reoriented and prevents the unintended prolonged effects of sedation. Such interruptions also help in assessing the patient for the appropriateness of weaning and hasten the transition to spontaneous respiration. Studies have demonstrated that protocols driven by respiratory therapy safely decrease the number of ventilator days. These protocols allow the respiratory therapists to begin spontaneous breathing trials (SBTs) when they consider the patient a candidate for weaning. Elevating the head of the patient's bed by greater than 30° decreases the risk of ventilator-associated pneumonia (VAP). Likewise, rates of VAP can be decreased with implementation of GI prophylaxis with histamine-2 blocking agents or proton-pump inhibitors, as well as deep vein thrombosis prophylaxis. Each of these measures should be undertaken in all patients receiving mechanical ventilation unless a contraindication is present. PEEP adjustment A PEEP level of less than 10 cm water rarely causes hemodynamic problems in the absence of intravascular volume depletion. The cardiodepressant effects of PEEP are often minimized with judicious intravascular volume support or cardiac inotropic support. Although peak pressure is related to the development of barotrauma, arterial hypotension is related to the mean airway pressure that may decrease venous return to the heart or decrease right ventricular function. A PEEP level greater than 10 cm water is generally an accepted indication to monitor cardiac output by using a Swan-Ganz catheter. However, if the patient remains clinically stable with an adequate urine output, then hemodynamic monitoring may not be necessary. When PEEP greater than 10 cm water is necessary, the left atrial filling pressure can be estimated after an adjustment is made for the effect of the PEEP on the transducer of the catheter. The equation commonly used is LAP = PCWP - (PEEP/3), where LAP is left atrial pressure and PCWP is pulmonary capillary wedge pressure. Withdrawal of PEEP from a patient should not be attempted in most clinical situations until the patient has achieved satisfactory oxygenation with an FIO2 of 40% or less. Formal weaning from PEEP is then undertaken by reducing the PEEP in 3- to 5-cm of water decrements while the hemoglobin-oxygen saturations are monitored. An unacceptable decrease in the hemoglobin-oxygen saturation should prompt the clinician to immediately reinstitute the last PEEP level that provided good hemoglobin-oxygen saturation. When to withdraw mechanical ventilation Weaning or, as some physicians prefer, "liberation from mechanical ventilation," is an important issue. Unnecessary delays in the withdrawal of mechanical ventilatory support increase the patient's risks for complications and increase the length of ICU stay and hospital costs. However, premature withdrawal from the ventilator can also be deleterious. Weaning should be considered when the event that precipitated the patient's need for mechanical support is adequately addressed. Patients should be evaluated each day to determine if they are a candidate for weaning. Patients who may be able to support their own ventilation and oxygenation can often be recognized by assessing objective measurements or by asking the following questions: * Is the process responsible for the patient's respiratory failure resolving or improving? * Is the patient hemodynamically stable? Is the patient free of active cardiac ischemia or unstable arrhythmias, and vasopressor support absent or minimal? * Is oxygenation adequate with a PaO2 of greater than 60 mm Hg with an FiO2 of less than 40% and a PEEP of less than 5 cm water? * Are mental and neuromuscular statuses appropriate with the patient on minimal or no sedation? Does the patient have adequate strength of the respiratory muscles? * Are the acid-base status and electrolyte status optimized? * Is the patient afebrile? * Are the patient's adrenal and thyroid functions adequate to allow for weaning? Numerous weaning parameters can be used to help predict successful extubation. However, no weaning protocol is 100% accurate in predicting successful weaning and extubation. These weaning parameters must be tailored for each clinical scenario. For instance, if the rapid, shallow breathing index (the respiratory rate/tidal volume, or frequency/tidal volume [f/Vt]) is less than 105, the patient is likely to be weaned from mechanical ventilation. The investigators who derived this number examined primarily middle-aged patients. However, data from follow-up studies of patients older than 70 years suggest that a slightly higher rapid, shallow breathing index of less than 130 may be acceptable. These parameters give no insight into whether a patient can protect his or her airway or clear secretions. Clinical judgment and experience play a large role in the physician's decision to withdraw mechanical ventilatory support. If a patient cannot be extubated and/or if the results of the rapid, swallow breathing test are not satisfactory, the reason for the failure must be evaluated and treated. Parameters commonly used to assess a patient's readiness to be weaned from mechanical ventilatory support include the following: * Respiratory rate less than 25 breaths per minute * Tidal volume greater than 5 mL/kg * Vital capacity greater than 10 mL/k * Minute ventilation less than 10 L/min * PaO2/FIO2 greater than 200 * Shunt (Qs/Qt) less than 20% * Negative inspiratory force (NIF) less than (more negative) -25 cm water * f/Vt less than 105, or less than 130 in elderly patients How to withdraw mechanical ventilation Weaning from mechanical ventilation is intended to shift the work of breathing from the ventilator back to the patient over time. An issue separate from discontinuing ventilator support is determining if the patient can maintain his or her airway and be extubated safely. The weaning process must ensure the patient's safety while avoiding undue delay that might increase the risk of VAP. The 3 general approaches to weaning are synchronized intermittent mandatory ventilation (SIMV), pressure-support ventilation (PSV), and an SBT. In SIMV, breaths are either a mandatory ventilator-controlled breath or a spontaneous breath with or without pressure support. The original intent of SIMV was to let the patient's respiratory muscles rest during the mandatory breaths and to work during the spontaneous breaths (see Media File 8). Weaning is accomplished by decreasing the number of mandatory breaths, gradually increasing the workload of the respiratory muscles. Weaning is typically done by 2 breaths every 12 hours. The patient's heart rate, respiratory rate, and oxygen saturation indicate his or her ability to accept the work of breathing. The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for synchronized intermittent mandatory ventilation (SIMV). The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for synchronized intermittent mandatory ventilation (SIMV). Evidence now suggests that the respiratory muscles are not able to rest during the mandatory breaths and that this mode may actually result in muscle fatigue and prolonged mechanical ventilation. Findings from randomized trials suggest that SIMV weaning delays extubation compared with PSV and SBT and that it should not be the primary mode of weaning in most patients. However, SIMV weaning does ensure that the patient receives some ventilatory support, and it may be favored in institutions where the staffing level of respiratory therapists is not optimal. In PSV weaning, all breaths are spontaneous and combined with enough pressure support to ensure that each breath is a reasonable tidal volume. The pressure support lowers the work of breathing for the patient. Weaning is performed by gradually decreasing the amount of pressure support and by transferring an increased proportion of the work to the patient. This transfer is continued until the pressure support approaches 5-6 cm water. When the patient can tolerate this level of ventilatory support, extubation is usually successful. Studies have demonstrated that PSV weaning reduces the number of days on mechanical ventilation compared with SIMV alone. PSV can be used in conjunction with SIMV when a patient is weaned from mechanical ventilation (see Media File 9). The coupling of these 2 modes is an especially attractive option in frail patients with underlying chronic illnesses. The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for synchronized intermittent mandatory ventilation (SIMV) with pressure-support ventilation. The pressure, volume, and flow to time waveforms ... The pressure, volume, and flow to time waveforms for synchronized intermittent mandatory ventilation (SIMV) with pressure-support ventilation. The preferred method of weaning is the SBT. This is an attempt to gauge how the patient might do if he or she is immediately removed from the ventilator. This method is also referred to as the sink-or-swim trial. The key is to withdraw ventilatory support while oxygenation is continued. The simplest form of SBT is the T-piece trial. The patient is disconnected from the ventilator, and the endotracheal or tracheostomy tube is hooked to a flow-by oxygen system, usually from the wall. The transition from the ventilator tubing to the new tubing attached to the wall oxygen outlet requires extra work and patient monitoring by the respiratory therapist. The same assessment can be made by using the continuous positive-airway pressure (CPAP) mode while the patient is still connected to the ventilator. This is a relatively common method of assessing the patient's ability to do the work of breathing by himself or herself. Variations on this theme include adding a small amount of pressure and using a CPAP of 5 cm water or a CPAP of 0 but with a PSV of 5-6 cm water to offset the resistance from the artificial airway. To the authors' knowledge, no controlled studies have shown any superiority in assessing the outcomes of weaning between these approaches. In some studies, approximately 80% of patients receiving mechanical ventilation do not require prolong weaning. This observation explains why SBT is both useful and practical. This approach has had the most success with weaning in randomized controlled trials. Therefore, it is a preferred approach to removing patients from mechanical ventilation. The SBT should last 30-90 minutes. At the end of the SBT, the patient should be evaluated for possible extubation, as his or her blood pressure, respiratory rate, heart rate, and gas exchange are also considered. An SBT should be performed only once a day. Several SBTs a day offer no benefit. Complications of Mechanical Ventilation Complications can occur at any stage of mechanical ventilation and are sometimes life threatening. Complications of intubation Complications that can occur during placement of an endotracheal tube include upper airway and nasal trauma, tooth avulsion, oral-pharyngeal laceration, laceration or hematoma of the vocal cords, tracheal laceration, perforation, hypoxemia, and intubation of the esophagus. Inadvertent intubation of the right mainstem bronchus is reported in 3-9% of all intubations in adults. Aspiration rates are 819% in intubations performed in adults without anesthesia. Sinusitis, tracheal necrosis or stenosis, glottic edema, and VAP may occur with prolonged use of endotracheal tubes. Additionally, the following guidelines from the American Association for Respiratory Care may be helpful: Removal of the endotracheal tube2007 revision update. Additionally, Solsona et al reported that observation of intercostal retraction after adding dead space may A mechanical ventilator is a machine that assists breathing. This article discusses the use of mechanical ventilators in infants. WHY IS A MECHANICAL VENTILATOR USED? A ventilator is used to provide breathing support for ill or immature babies. Sick or premature babies often have breathing problems, and cannot breathe adequately on their own. They need assistance from a ventilator to provide “good” air (oxygen) to the lungs and to remove “bad” air (carbon dioxide). HOW IS A MECHANICAL VENTILATOR PLACED? A ventilator is a bedside machine that is attached to the breathing tube that is placed into the windpipe of sick babies. Caregivers can adjust the ventilator as needed, depending on the baby's physical findings, blood gas measurements, and x-rays. WHAT ARE THE RISKS OF A MECHANICAL VENTILATOR? Most babies who need ventilator assistance have some degree of lung problems, including fragile lungs, which are at risk for injury. Sometimes the delivery of oxygen under pressure can result in damage to the fragile air sacs. This can lead to air leaks, which can make it difficult for the ventilator to help the baby breathe. * The most common type of air leak occurs when air gets into the space between the lung and inner chest wall. This is called a pneumothorax. This air can be removed with a tube placed into the space until the pneumothorax heals. * A less common kind of air leak occurs when many tiny pockets of air are found in the lung tissue around the air sacs. This is called a pulmonary interstitial emphysema. This air cannot be removed but usually slowly goes away on its own. Long-term damage may also occur, resulting in a form of chronic lung disease that is called bronchopulmonary dysplasia. This is why the caregivers closely monitor and attempt to “wean” or decrease the settings on the ventilator whenever possible. It is the baby's needs, however, that determine the level of support needed in most circumstances. |