Monday, September 26, 2022

Causes Of Ventilator Associated Pneumonia

Ventilator Complications: Other Risks

Ventilator Associated Pneumonia (VAP) Explained Clearly | Part 1

Delirium: Youre usually unconscious or heavily sedated when you’re on a ventilator. Either way, you take strong medications. Sometimes, these drugs may take some time to wear off even after the tube is removed from your airway.

You may have a hard time reading, writing, or thinking clearly. You also might notice a poor memory, have trouble sleeping, feel anxious, or have unusual emotions like paranoia. Talk to your doctor about these effects, which should fade over time.

Immobility: Because you’re sedated, you dont move much when you’re on a ventilator. That can lead to bedsores, which may turn into skin infections. You’re more likely to get blood clots for the same reason. Your muscles, including those that normally help you breathe for yourself, may get weak. You might need rehab with a physical or respiratory therapist.

Vocal cord problems: When your doctor removes the breathing tube to take you off the ventilator, it can damage your vocal cords. Expect some soreness and a raspy voice at first. But let your doctor know if its hard to breathe or speak after the tube comes out.

Preventing Colonization And Aspiration

Regular oral care, assessment of the need for proton-pump inhibitor and histamine-2-receptor blocker therapy, and early identification and treatment of dysphagiaâespecially in the elderly and in patients with recent stroke or surgical proceduresâare key features to preventing oropharyngeal colonization of pathogenic organisms, aspiration, and ensuing HAP or VAP. A systematic review and meta-analysis including 2 studies of critically ill, nonventilated patients reported significant risk reduction in HAP through the use of chlorhexidine oral cleansing, electric tooth-brushing, and oral hygiene instruction.

Data supporting oral care in VAP prevention are more robust, with several institutions worldwide reporting reduced VAP incidence in association with ICU âbundlesâ including an oral care component.

One institution implemented a protocol involving twice-daily chlorhexidine oral cleansing in addition to elevating the head of the bed to more than 30 degrees, once-daily respiratory therapy-driven weaning attempts, and conversion from a nasogastric to an orogastric tube as feasible for all ventilated trauma patients. One year after this protocol was implemented, the incidence of VAP had declined, and patients without VAP accrued fewer total ventilator days, ICU days, and hospital days, although their mortality rate was no lower than in patients with VAP.

Aspiration Is An Important Cause Of Hap And Vap

Aspiration is an important contributor to the pathogenesis of HAP and VAP. Further, proton-pump inhibitors and histamine-2 receptor blockers, by suppressing acid production, can allow nosocomial pathogens to colonize the oropharynx and endotracheal tube and be aspirated. VAP-specific risk factors such as age, recent surgery, and admission for neurologic causes or cardiovascular failure all increase the risk of aspiration.,

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Ventilator Associated Pneumonia An Overview

Harshal Wagh and Devaraja Acharya

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Abstract

Ventilator Associated Pneumonia is pneumonia occurring in a patient within 48 hours or more after intubation with an endotracheal tube or tracheostomy tube and which was not present before. It is also the most common and fatal infection of ICU. VAP increases length of ICU stay by 28% and each incidence of VAP is estimated to generate an increased cost of £6000- £22000. The NICE in collaboration with NPSA is examining four technical patient safety solutions for the prevention of VAP. The Department of Health published a High impact intervention for ventilated patients in June 2007. Eliminating or reducing the unnecessary use of antibiotics should be the primary goal in reducing antibiotic-resistant nosocomial infections.

Ventilator Associated Pneumonia is defined as pneumonia occurring in a patient within 48 hours or more after intubation with an endotracheal tube or tracheostomy tube and which was not present before1, 2. Early onset VAP occurs within 48 hours and late onset VAP beyond 48 hours of tracheal intubation.

Incidence

Between 5-15% of hospital in-patients develop infection during admission to ICU3. Patients are 5-10 times more likely to acquire nosocomial infections than patients in the wards4and approximately 86% of hospital associated pneumonia is linked with mechanical ventilation5.

Diagnosis

Pathogenesis:

The pathogenesis of VAP usually requires that two important processes take place:

Prevention:

Why You Might Need A Ventilator

Ventilator associated pneumonias

You may need to be on a ventilator for days, weeks, or more if you have an injury or illness that makes it hard to breathe.

A ventilator also may help you breathe during surgery where you are asleep , but this is usually for no more than a few hours. Doctors sometimes use ventilators for operations because anesthesia drugs can interfere with your breathing.

To put you on a ventilator, your doctor sedates you. Then, they put a tube down your throat and into your windpipe. This makes it easier to get air into and out of your lungs. The process is called intubation.

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The 2013 Cdc Vae/vac Definitions

Most preventive strategies have shown a reduction in the incidence of VAP, but this has not translated to a definite outcome benefit such as a reduction in duration of ventilation, LOS, or mortality. As ICU patients are a heterogeneous group of patients with multiple factors affecting their individual outcome, it is often difficult to show an outcome benefit from a single intervention. Another complicating factor is that the criteria used for diagnosis of VAP vary from study to study. Often, they are based on clinical criteria only. This cannot solely be blamed on study design as critical care societies and other governing bodies have so far not been able to agree upon common diagnostic criteria. As VAP rates are related to surveillance and carry monetary fines, it has become imperative that a common overarching definition is agreed upon. It was with this intention that a new official multisociety definition was created last year .

2013 CDC VAE/VAC definitions

2013 CDC VAE/VAC definitions

Other problems with the new definition that will require modification include adjustments in the level of PEEP due to non-respiratory conditions, use of antibiotics for non-respiratory conditions, excluding manoeuvres used to provide comfort care in terminally ill patients from constituting a VAC.

Pearls And Other Issues

  • Summary of risk factors for ventilator-associated pneumonia and the area of focus for prevention include: treatment factors that promote colonization of oropharynx or stomach, factors that promote gastric reflux and aspiration like depressed mental status, supine position, nasogastric tubes, duration of intubation and mechanical ventilation, and factors that interfere with adequate pulmonary toilet, thoracic or abdominal surgery or immobilization.
  • Methods for decreasing the incidence of ventilator-associated pneumonia include but are not limited to the following, and most institutions utilize prevention bundles to reduce the risk: judicious use of reflux medications, removal of unnecessary nasogastric tubes, and daily evaluation of readiness to extubate, pain-control, and maintenance of mechanical ventilation system are all part of protocols ICUs use to decrease the rate of ventilator-associated pneumonia.

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Sampling Of Secretions In The Distal Airway

Distal airway samples may be obtained by using bronchoscopic or nonbronchoscopic techniques. With nonbronchoscopic techniques, a catheter is blindly advanced through the endotracheal tube or tracheostomy and wedged in the distal airway. Various sampling methods include blind bronchial suction , blind bronchoalveolar lavage , and blind protected-specimen brush sampling. Their sensitivities and specificities, respectively, are as follows :

  • BBS – 74-97% and 74-100%

  • Blind BAL – 63-100% and 66-96%

  • Blind PSB sampling – 58-96% and 71-100%

When nonbronchoscopic techniques are used, the diagnostic threshold may vary according to the method used. Cultures tend to be above the diagnostic threshold with bronchoscopic procedures more often than they are with nonbronchoscopic procedures.

Enhancing Healthcare Team Outcomes

What is VAP? (Ventilator-Associated Pneumonia) | Medical Definition

Ventilator-associated pneumonia is usually managed by an interprofessional team that includes an intensivist, pulmonologist, respiratory therapy, ICU nurse, dietitian, pharmacist, and thoracic surgeon. The key with VAP is to reduce the risk by enforcing preventive techniques in patient care. All the modifiable risk factors should be addressed such as endotracheal and tracheostomy suctioning, use of gastric acid modifying agents, enteral nutrition, hand washing and single use of equipment. The supine position should be avoided, and one should minimize transport of the patient in and out of the ICU. The cuff pressure of the endotracheal tube should be at 20 mmHg or above, to help prevent passage of oropharyngeal contents into the lower airways. The pharmacist should ensure that the right antibiotics are selected and that there is a recycling of the medications to avoid the development of resistant organisms. The patient must be fed enterally whenever possible. Finally, there should be protocols for weaning and early extubation in order to avoid VAP.

Outcomes

In general, VAP is associated with a higher mortality when the patient has numerous comorbidities. However, younger patients with no additional organ involvement do tend to have a good prognosis without any major sequelae. Higher mortality rates have been reported in older patients, diabetics, those with COPD, smokers and poor functional status.

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Management Of Hap And Vap

Although delaying the start of antibiotic therapy is associated with a higher risk of death in the context of sepsis, recent studies argue that antibiotics may not be immediately required in every patient with suspected HAP or VAP.

Two different strategiesâclinical and bacteriologicâcan be used in this decision. In the clinical strategy, antibiotics are started in patients with a new pulmonary infiltrate concerning for HAP or VAP if they meet 2 of the following 3 criteria: fever, productive cough, and leukocytosis. In the bacteriologic strategy, antibiotics are held until quantitative cultures of lower respiratory tract samples confirm a diagnosis of HAP or VAP.

A single-center observational study comparing these 2 strategies noted that, while patients managed with the clinical strategy were rapidly started on antibiotics, they experienced a lower chance of receiving initially appropriate therapy, a longer duration of treatment, and a significantly higher rate of in-hospital mortality, possibly due to selection of resistant organisms. However, certain patients do merit prompt and aggressive antibiotic therapy even before culture results become available: those with hemodynamic or respiratory instability, those with immunocompromised status, and those for whom timely sampling of lower respiratory tract secretions is not feasible.

Initial Empiric Coverage Of Mrsa Gram

Once the decision to treat a patient with suspected HAP or VAP is made, an institution-specific antibiogram should guide the selection of an empiric antibiotic regimen that best addresses local organism prevalence and antibiotic resistance patterns. If such an antibiogram is not readily available, a regimen with empiric coverage of methicillin-susceptible S aureus and gram-negative bacilli such as P aeruginosa should be selected, eg, piperacillintazobactam, cefepime, levofloxacin, imipenem, or meropenem.

One antipseudomonal agent or two? Patients who recently received intravenous antibiotics or are at high risk of death merit double coverage of P aeruginosa with antibiotics from 2 different classes for empiric treatment of HAP. Placement in an ICU where more than 10% of gram-negative isolates are resistant to an agent being considered for monotherapy is an additional indication for the initiation of 2 antipseudomonal agents to treat VAP. Patients with P aeruginosa pneumonia complicated by bacteremia who receive empiric antipseudomonal combination therapy have a lower mortality rate than those who receive antipseudomonal monotherapy. Combination therapy ensures timely initiation of at least 1 active agent. Patients who receive anti pseudomonal monotherapy may experience delays to the initiation of an appropriate antipseudomonal agent if resistance to the chosen agent is present.

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Antimicrobial Treatment Of Ventilator

What is not controversial?

Immediate initiation of appropriate antimicrobial treatment has a significant impact on clinical outcome of patients with VAP. In a paradigmatic study, Luna et al. illustrated that inappropriate initial empiric antimicrobial treatment was significantly associated with increased mortality. Moreover, excess mortality could not be reduced by correction of inappropriate regimens according to results of microbial investigation. On the other hand, it was also shown that antimicrobial pretreatment may favour the selection of multiresistant pathogens and, thereby, cause excess mortality . Thus, any policy of empiric antimicrobial treatment must outweigh potentially associated benefits and risks.

What is still controversial?

Whereas the criterion admission to the ICU, suggested in the ATS guidelines, can identify patients who are at risk of PDRMs, it does not seem to be a satisfactory criterion for severe VAP. Accordingly, the definition of severity needs to be validated. Another issue that might have been underestimated is the differentiation of the nonventilated from the ventilated patient. Possibly, the algorithm should start from this differentiation.

What should be investigated?

Bacteriological And Histological Aspects Of Ventilator

PPT

What is not controversial?

Polymicrobial and multifocal VAP is one of the major unresolved diagnostic issues. More than one pathogen is found in around 3070% of VAP cases. Not only is there a scattered distribution of inflammation throughout the lung, but also of different pathogens, e.g. Rouby et al. showed that in monomicrobial bronchopneumonia, causative micro-organisms were found in all lobes in 50%, and in only one of the two lobes in 50% of cases. In polymicrobial pneumonias, all bacteria involved in the infectious process were found in all lobes in only one third of the cases, whereas different bacteria were found in lower and upper lobes in 25% of the cases. The authors also noted partial discrepancies in the remaining 42% of polymicrobial bronchopneumonias with all bacteria found in one lobe and only some of them in the other lobe . Another problem is the unequal distribution of infection in central and peripheral areas of the lung. In one study it was shown that in several cases, pneumonia was absent from peripheral lung samples while more central areas of the same segment displayed pneumonia .

What is controversial?

What has to be investigated?

In order to cope with these extremely demanding investigational aims, one important point is to adhere to recommendations concerning lung tissue processing as given in one of the previous consensus conferences .

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Leakage Prevention: Subglottic Secretions Drainage And Ett Cuff Modifications

ETT modifications have been proposed to target the prevention of micro-aspiration. One strategy is based upon the preemptive evacuation of the fluid collected upon the cuff through suctioning before the fluid passes the cuff. Others innovations apply to the cuff itself, in attempting to improve its performance in sealing the tracheal lumen.

Subglottic Secretions Drainage.

SSD is performed through a specially modified ETT equipped with a suctioning channel opening just above the inflated cuff. Suctioning can be delivered continuously or intermittently to remove the secretions. The benefit of one technique over the other has not been established. In a meta-analysis, the relative risk reduction was similar for the continuous and intermittent suctioning. CSSS, despite using lower negative pressure than the intermittent strategy, has been associated with tracheal mucosal lesions in all animals treated with CSSS for 72 hours, and no study has shown its safety in humans. Most of the literature confirms some beneficial effect on pneumonia development associated with SSD, but low impact has been found on clinical outcomes., Despite the usefulness of SSD as a prevention tool in VAP management, controversial evidence about its utility and concerns about safety may limit its use in clinical settings.,

ETT Cuffs.

Care Of Airway Equipment

Studies have shown that TT colonization and biofilm formation begins within 24 h of intubation. Strict attention to hand hygiene when handling the TT, closed-circuit suction systems, use of heat and moisture exchangers, and limiting ventilator tube changes to whenever they are soiled, all contribute towards reducing biofilm formation.

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Prevention Of Deep Venous Thrombosis

Measures should be taken to prevent deep venous thrombosis. The selection for the method of deep venous thrombosis prevention should be based on individual patient characteristics and comorbid illnesses. Heparin, low-molecular-weight heparin, and compression stockings are means to help prevent deep venous thrombosis.

Sampling Of Secretions In The Proximal Airway

Community-Acquired Pneumonia (Medical Definition) | Quick Explainer Video

Qualitative endotracheal aspirates are easy to obtain but have a high false-positive rate in ICU patients because of airway colonization. When quantitative endotracheal-aspirate cultures are used, a cutoff value of 106 is the most accurate, with a sensitivity of 38-82% and a specificity of 72-85%. However, when this cutoff is used, approximately 33% of patients with ventilator-associated pneumonia may be missed. Only 40% of endotracheal-aspirate cultures coincide with results of protected brush sampling. Therefore, adjusting antibiotics on the basis of findings from endotracheal aspirates may lead to inadequate coverage of the causative pathogens.

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Common Causes Of Ventilator Associated Conditions

Grace Lee, MD, MPH, associate medical director, Infection Control, Boston Childrens Hospital, discusses the different causes of ventilator-associated conditions in adult populations and neonatal intensive care units.

Grace Lee, MD, MPH, associate medical director, Infection Control, Boston Childrens Hospital, discusses the different causes of ventilator-associated conditions in adult populations and neonatal intensive care units.

Interview Transcript

Ventilator-associated conditions are events that are indicated by worsened oxygination for patients who are on a ventilator. The surveillance definition was put into place by National Healthcare Safety Network in January 2013 for the adult population. There is currently a proposed definition on the table for neonates and children, that will be adapted from the adult VAC definition in the near future.

The most common causes of VAC in the adult population include pneumonia, pulmonary edema, atelectasis and . Were doing some preliminary work in neonates and children, and finding that while there are some common causes, such as pneumonia, pulmonary edema and atelectasis, there also some different causes, particularly in the neonatal , where respiratory distress syndrome and bronchopulmonary dysplasia, as well as sepsis or shock are more common causes of VAC.”

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How To Prevent Ventilator

Even if a patient needs intubation, caregivers and home care nurses can implement many different strategies and practices to lessen the chances of VAP occurring. The care teams can implement these practices:

  • Elevate the patients head at an angle of 30 to 45 degrees

  • Thoroughly wash hands before and after touching a ventilator

  • Regularly clean the inside of the patients mouth, including regular use of an antiseptic solution

  • Only use a ventilator when necessary

  • Minimize sedation

  • Regularly remove fluids out of the airway

  • Aspiration of patient secretions, keeping equipment clean, and propping up patients in bed can go a long way toward maintaining the health of those on ventilators. The CDC also recommends using positive-pressure ventilation via a face or nose mask combined with proactive surveillance of the ventilated patient. For some patients, a continuous airway pressure or a bilevel positive airway pressure machine effectively provides sufficient oxygen and eliminates the need for intubation.

    Keeping the patient propped at the proper angle can reduce the occurrence of VAP by up to 67 percent during the first 24 hours of intubation. Several observational or randomized studies confirm that patient position can affect the incidence of VAP. Thats not the only way to help reduce it. Other strategies involve techniques and monitoring by respiratory therapists. Nevertheless, you should be aware of what can be done. These include:

  • Clean the ventilator twice daily

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