Slide 1 VENTILATOR MADNESS.. MAKING SENSE OF IT ALL!! Maryann M Brogden ND, MSN, RN, APN-C, CCNS, SCRN Slide 2 I have nothing to disclose. Slide 3 Objectives: Identify Criteria for Intubation Differentiate common modes of mechanical ventilation Identify and troubleshoot common ventilator alarms
Slide 4 Normal Ventilation Normal ventilation without supportive mechanical ventilation requires : Intact rib cage Diaphragm and respiratory muscles that can contract Ability to maintain a patent airway No interference with intrapleural or intraalveolar pressures All must be present to facilitate normal gas exchange. Slide 5 Indications for Mechanical Ventilation Most common indication- acute respiratory failure/respiratory acidosis Others: Unable to stabilize the chest (trauma, penetrating injuries) Cardiogenic or septic shock Severe asthma/anaphylaxis Acute respiratory distress syndrome(ards) Pneumonia Burns/smoke inhalation Neuromuscular disease Slide 6 Indications for Mechanical Ventilation Overdose Brainstem injury Chronic obstructive pulmonary disease (COPD) So when we focus on respiratory failure it is essential to determine the underlying cause. Is it a ventilation issue, an oxygenation issue, or both???
Slide 7 Ventilation issue An example of a ventilation issue would include conditions that cause massive atelectasis. In this case the ventilation demand exceeds the ventilation supply and the respiratory muscles fatigue with the increase work of breathing This condition is referred to hypercapnic respiratory failure. Slide 8 Perfusion issue Pulmonary embolus-perfusion issue within the lungs Oxygenation issue or hypoxemic respiratory failure Creates a physiologic shunt in which ventilation is not interfacing with the pulmonary capillaries, increasing hypoxemia Slide 9 Reasons for Intubation Severe acidosis or hypoxemia Severe dyspnea Respiratory arrest Cardiovascular instability Aspiration risk Copious/viscous secretions Facial trauma Extreme obesity
Slide 10 Physiologic Indications Acute respiratory failure - pt unable to maintain acidbase balance and the normal exchange of CO2 and O2 Reflected in arterial blood gas PaO2 <60mmHg FiO2 > than 0.50 ph of < than 7.25 Arterial PaCO2 < 30 > 50 Respiratory rate >35/min In addition to worsening ABGs, the patient may demonstrate clinical signs of deterioration. If not reversed, pt tires and cannot maintain respiratory effort Slide 11 Pathophysiologic Causes of Acute Respiratory Failure Four most common causes: 1. Hypoventilation pt retains CO2 becomes hypoxic Examples: damage or depression neurologic system, head injury, hemorrhage, cerebral thrombosis, COPD 2. V/Q mismatch Examples: asthma, pneumonia, tumors, PE, excessive PEEP 3. Shunting-blood bypasses the alveolar-capillary unit (anatomic shunt), or blood goes through the alveolar capillary unit but is nonfunctional (physiologic shunt)-oxygenation does not take place Examples: physiologic shunt-atelectasis, pneumothorax, pneumonia, cardiac, pulmonary edema 4. Diffusion effects Examples: emphysema, tumors Slide 12 Common Ventilator Modes Mode of Ventilation: Method of inspiratory support provided by the mechanical ventilator Specific combination of breathing pattern and control variables to deliver inspiration Five Basic Modes: Volume control Volume assist Pressure control Pressure assist Pressure support Other modes: High frequency oscillatory ventilation(hfov) Continuous positive airway pressure (CPAP)
Slide 13 Volume-targeted Modes Tidal Volume (V T ) is the targeted parameter Fixed V T is delivered with each breath Most commonly used modes May be labeled by different names including Controlled mandatory ventilation Continuous mandatory ventilation Assist/Control (A/C) mode ventilation Slide 14 Volume-Targeted Modes The V T is preset and is delivered by the ventilator until the preset volume is reached In this mode the ventilator performs all the work of breathing, without the patient initiating any effort This mode is useful when patient experiencing apnea (neurological condition or drug overdose) Slide 15 Volume-Targeted Modes Can be used to fully rest the patient s diaphragm and respiratory muscles to allow healing of the underlying respiratory condition To promote patient comfort, the sensitivity dial is set at -1 to -2 cm to permit the pt to trigger a ventilator breath with little effort If the pt is attempting to initiate a breath and the flow rate does not match inspiratory efforts, this can Increase the work of breathing Create anxiety Cause shortness of breath This requires immediate alteration of the flow-rate setting!
Slide 16 Volume-Targeted Modes An example of this mode is A/C ventilation The clinician orders the following: Respiratory rate V T Sensitivity FiO2 Positive End Expiratory Pressure (PEEP) When the patient initiates a breath, it will be delivered at the full preset V T Slide 17 Volume-Targeted Modes Synchronized Intermittent Mandatory Ventilation (SIMV) is also a volume-targeted mode of ventilation Similar to A/C, the SIMV pt will receive a preset V T at a preset rate The pt may initiate spontaneous breaths above the preset rate at the pts own spontaneous V T This mode is helpful for the pt with an intact respiratory drive but with weakened respiratory muscles Slide 18 Pressure-Targeted Modes A mode in which the volume of gas is delivered until the preset pressure has been reached Breaths are triggered by the patient Mode may be used independently or in conjunction with other modes The pt may receive a variable V T, depending on Lung compliance Airway compliance Circuit compliance
Slide 19 Pressure-Targeted Modes Two of the most common: Pressure-support (PS) Pressure-controlled (PC) With PS the pt s spontaneous breaths are augmented with a preset amount of inspiratory pressure To utilize this mode the pt s respiratory drive must be intact in order for the pt to initiate spontaneous breaths Using PS negates the resistance of the artificial airway and ventilator circuit, resulting in decreased work of breathing Slide 20 Pressure-Targeted Modes Clinicians orders parameters for: PS level Sensitivity FiO2 PEEP When high levels of PS are required, it is considered to be full ventilator support Can also be utilized in conjunction with other modes to supplement spontaneous breaths, as well as with SIMV The main advantage of this mode is the control the pt has over the ventilatory process Slide 21 Pressure-Targeted Modes PC ventilation is the mode in which a respiratory rate is set and every breath is augmented by a preset amount of inspiratory pressure. Once triggered, the gas is delivered until the preset pressure is reached If pt takes spontaneous breaths, those breaths are also augmented by the preset inspiratory pressure
Slide 22 Pressure-Targeted Modes The clinician orders parameters for: Inspiratory-pressure limit Respiratory rate Inspiratory time Sensitivity FiO2 PEEP This mode is useful as a lung-protective strategy for the pt with low lung compliance, such as acute respiratory distress syndrome (ARDS). This mode also helps in controlling high-plateau pressures, which prevent the pt from developing barotrauma. Slide 23 Pressure-Targeted Modes Inverse-ratio ventilation (IRV) This mode is useful when the pt has poor oxygenation despite high FiO2, PEEP, and positioning. The clinician orders: Respiratory rate Sensitivity FiO2 PEEP The inspiratory time is set to provide a longer inspiration in order to improve oxygenation. Uncomfortable to pt, sedation and possibly paralytics are required to prevent pt-ventilator dyssynchrony and desaturation. Slide 24 Other Modes High Frequency Oscillatory Ventilation-(HFOV) This is a type of ventilation known as a rescue mode for a pt experiencing refractory hypoxemia This mode of ventilation delivers small V T at a rapid rate of 300 to 400 breaths per minute The ventilator delivers this high rate with a highfrequency oscillation known as hertz (Hz)
Slide 25 HFOV-continued This creates a wave or oscillation that promotes the elimination of carbon dioxide and improves oxygenation by preventing alveolar collapse. (Bartolotto & Makic, 2012; Haas & Bauser, 2012) This mode diminishes the phenomenon known as stacking of breaths during exhalation. Slide 26 HFOV-cont When the breath is not fully exhaled, air is trapped in the non-compliant lung, which is known as auto PEEP. Auto PEEP can cause increased intrathoracic pressures, leading to decrease in cardiac output, or barotrauma. Requires special ventilator that uses a piston to drive the gas flow in and out of the lung Utilized in moderate-to-severe ARDS Oscillate Trial Slide 27 Other Modes-CPAP Continuous Positive Airway Pressure (CPAP) Refers to delivery of a continuous level of positive airway pressure maintained throughout the respiratory cycle The ventilator does not provide any breaths during CPAP; the pt must initiate all breaths If a pt is on CPAP of 5cm H2O, 5cm of positive pressure is applied to the airway on inspiration and expiration
Slide 28 Other Modes-CPAP CPAP similar to PEEP, is used to restore and maintain the amount of air left in the lungs at end expiration, or functional residual capacity. The application of positive pressure to the airways during expiration may keep alveoli open and prevent early closure during expiration. The presence of an artificial airway allows intrathoracic pressure to decrease to zero, which is below the usual level of intrathoracic pressure. Slide 29 Other Modes-CPAP PEEP/CPAP levels of 5 cm H2O are often used to provide physiologic PEEP. May be used in last step in the process of discontinuing mechanical ventilation or used as a noninvasive method of providing a pneumatic splint to the airways in pts with obstructive sleep apnea (OSA) Opening the airways with positive pressure prevents the upper airway from collapsing with each breath. Slide 30 Trouble-Shooting Common Alarms The trouble shooting process is guided by the severity of the distress and the stability of the pt s condition If the pt is in severe respiratory distress or hemodynamically unstable, the pt should be immediately disconnected from the ventilator and manually bagged with 100% O2. If the pt rapidly improves most likely the problem is in the vent settings or circuit. If pt appears anxious, short of breath, or the alarms sound, immediate systemic assessments should occur.
Slide 31 Trouble-Shooting Alarms Always place the initial focus on the pt and not the ventilator!! Avoid the false sense of security that because a pt is supported by the ventilator, that he/she is receiving adequate ventilation The ventilator alarm can be silenced for up to 2 minutes, plenty of time to perform an assessment Assessment includes: Hemodynamic stability Excessive secretions Anxiety Pain Securement of tubing Appropriateness of vent functions and settings Slide 32 Trouble-shooting alarms High pressure alarm is triggered because 2 consecutive breaths are limited when they reach the high pressure setting Inspiratory pressure phase ends (no more volume is delivered) Exhalation valve opens to prevent excess pressure (determined by upper pressure alarm limit) Causes: Blocked or kinked tube Other increased airway resistance Decreased lung compliance factors Anything that increases peak pressure to above limit, resulting in established volumes not being delivered Slide 33 Trouble-Shooting: High Pressure Alarm Examples of factors that increase resistance: Biting down on tube Obstructed endotracheal tube (ETT) Coughing Secretions Increased respiratory rate Examples of factors that decrease lung compliance: Pulmonary edema Pneumonia Atelectasis Displacement of ETT Pneumothorax
Slide 34 Trouble-Shooting: High Pressure Alarm Interventions: Suction secretions as needed Make sure that condensation does not drain into pt s airway Prevent tube jarring and movement with positioning Administer bronchodilators as ordered Slide 35 Trouble-Shooting Alarms Low exhaled tidal volume alarm occurs if delivered tidal volume is less than delivered tidal volume alarm setting for 3-4 consecutive breaths. Causes: Air leaks in ventilator or nebulizer circuit Tear or crack in tubing Cuff leak Interventions: Evaluate that pt is connected to the vent Check all tubing connections Make sure that prescribed tidal volume is delivered Call for help when needed Evaluate Inflate cuff as needed for leaks Correct high pressure problems Slide 36 Trouble-shooting Alarms Low inspiratory pressure alarm occurs if monitored circuit pressure is low-below the setting on lowinspiratory pressure dial. Cause: Air leaks causing volume leaks. Interventions: Assess Correct air leaks in ETT, tracheotomy cuff, ventilator system Make sure prescribed tidal volume is delivered Call for help as needed
Slide 37 Trouble-shooting Alarms Apnea alarm occurs if the pt has not triggered a breath within the 20 second apnea interval This can only occur in spontaneous mode-pressure support ventilation Causes: Apnea Unstable ventilatory drive secondary to medications depressing the central nervous system Interventions: Check pt Ventilate manually Call respiratory therapy Slide 38 Questions??? Slide 39 References: Baird, M., & Bethel, S. (2011). Manuel of critical care nursing: Nursing interventions and collaborative management (6 th ed.). St. Louis, MO: Elsevier. Bortolotta, S., & Makic, M. (2012). Understanding advanced modes of mechanical ventilation. Critical Care Nursing Clinics, 24(3), 443-456. Brown, C.A. (2013). The decision to intubate. Retrieved from www.uptodate.com Hyzy (2013). Modes of Mechanical Ventilation. Retrieved from www.uptodate.com Grossbach, I.,Chlan, L., & Tracy, M. F. (2011). Overview of Mechanical Ventilatory Support and Management of Patient-and Ventilator-Related Responses. Critical Care Nurse, Vol.31, (3), 30-44. Goldsworthy, S., Graham, L. (2104). Compact clinical guide to Mechanical Ventilation: Foundations of Practice for Critical Care Nurses. New York, NY. Springhouse Publishing Company. High-Frequency Oscillation in Early Acute Respiratory Distress Syndrome. Niall D. Ferguson, M.D., Deborah J. Cook, M.D., Gordon H. Guyatt, M.D., Sangeeta Mehta, M.D., Lori Hand, R.R.T., Peggy Austin, C.C.R.A., Qi Zhou, Ph.D., Andrea Matte, R.R.T., Stephen D. Walter, Ph.D., Francois Lamontagne, M.D., John T. Granton, M.D., Yaseen M. Arabi, M.D., Alejandro C. Arroliga, M.D., Thomas E. Stewart, M.D., Arthur S. Slutsky, M.D., and Maureen O. Meade, M.D. for the OSCILLATE Trial Investigators and the Canadian Critical Care Trials Group N Engl J Med 2013; 368:795-805February 28, 2013DOI: 10.1056/NEJMoa1215554