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CASE REPORT
Year : 2009  |  Volume : 53  |  Issue : 3  |  Page : 344-347 Table of Contents     

Use of Adaptive Support Ventilation (ASV) in Ventilator Associated Pneumonia (VAP) - A Case Report


1 Assistant Professor, Department of Anaesthesiology & Critical Care, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh 517507, India
2 Dean & HOD, Department of Anaesthesiology & Critical Care, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh 517507, India

Date of Web Publication3-Mar-2010

Correspondence Address:
Bipphy Kath
Department of Anaesthesiology & Critical Care, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh 517507
India
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Source of Support: None, Conflict of Interest: None


PMID: 20640145

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Prolonged ventilation leads to a higher incidence of ventilator associated pneumonia(VAP) resulting in ventilator dependency, increased costs and subsequent weaning failures. Prevention and aggressive treatment of VAP alongwith patient friendly newer modes of ventilation like adaptive support ventilation go a long way in successful management of these cases.

Keywords: Adaptive support ventilation, Ventilator associated pneumonia, Nosocomial infection


How to cite this article:
Kath B, Hemanth N, Marella P, Rao M H. Use of Adaptive Support Ventilation (ASV) in Ventilator Associated Pneumonia (VAP) - A Case Report. Indian J Anaesth 2009;53:344-7

How to cite this URL:
Kath B, Hemanth N, Marella P, Rao M H. Use of Adaptive Support Ventilation (ASV) in Ventilator Associated Pneumonia (VAP) - A Case Report. Indian J Anaesth [serial online] 2009 [cited 2020 Apr 7];53:344-7. Available from: http://www.ijaweb.org/text.asp?2009/53/3/344/60301


   Introduction Top


Ventilator associated pneumonia (VAP) in the re­cent past has been threatening to be the most common and catastrophic nosocomial infection attributing to sig­nificant mortality and morbidity with severe impact on the healthcare costs incurred by the society [1] . VAP pre­sents to the clinician along with diagnostic dilemmas, difficulties in the ventilatory management of the patient as the source of the disease is the ventilator itself! We present a case report of successful management of VAP by using adaptive support ventilation (ASV), a newer novel mode of ventilation known to increase patient ventilator synchrony in a cost effective manner [2] .




   Case report Top


A 35-year-old man was admitted in emergency with head injury following road traffic accident. Patient presented with left ear bleed, nasal bleed and uncon­sciousness with GCS 3. Endotracheal intubation was performed and CT scan revealed right fronto-temporo­parietal acute sub dural haematoma and left parietal extradural haematoma with midline shift. Emergency craniotomy and evacuation was done and patient was electively ventilated for the next 24 hours. Post opera­tive CT scan showed diffuse axonal injury (DAI) with poor neurological recovery. Day 2 onwards patient required higher FiO 2 and so weaning was deferred [Table 1]. Elective tracheostomy was done on the 4th post operative day. Day 6 chest x-ray revealed con­solidation of left middle and lower lobes [Figure 1] with deteriorating PaO 2 / FiO 2 (P/F) ratios [Table 1]. Provi­sional diagnosis of ventilator associated pneumonia (VAP) was made with the Clinical Pulmonary Infection Score (CPIS) [3] of 7.

Patient was ventilated with volume controlled ven­tilation with high inspired oxygen concentration and PEEP. Endotracheal aspirates were sent for culture and sensitivity. Tracheal aspirate showed gram positive cocci in clusters and occasional gram negative bacilli. Broad spectrum antibiotics were already started. Rig­orous chest physiotherapy was instituted. Culture re­ports confirmed the growth of Pseudomonas aeruginosa and Staphylococcus aureus. Appropriate antibiotics were administered according to culture sensitivity.

Weaning was attempted over the next 4 days on SIMV (12 breaths) +Pressure support (15cm H 2 O) but failed as seen by worsening of blood gases. On the 10 th postoperative day mode of ventilation was changed to Adaptive support ventilation (Galileo ventilator by Hamilton medical systems). Minute volume was sup­ported 100% to start with and the response was moni­tored by clinical improvement and arterial blood gases. Over the next 4 days oxygenation improved (P/F ra­tios) [Table 1]. Support on minute volume was reduced in decrements of 10%. Chest physiotherapy, antibiot­ics and supportive measures (enteral feeds) were con­tinued. The 14th day chest x-ray showed clearing of lung zones [Figure 2]. On the 15 th day patient was on mini­mal ASV support (FiO2< 0.4, PEEP = 5cm of H2O, minute ventilation supported at 30%). Spontaneous breathing trial was given over the next few days by al­ternating between ASV and T-piece initially in the ratio of 2:1, followed by 1:1 and then 1:2. On day 19, pa­tient was weaned off the ventilator and shifted out of Neurosurgical ICU on 21st day [Figure 3]


   Discussion Top


Based on data from the National Nosocomial In­fection Surveillance System, VAP represents the most common nosocomial infection seen in the intensive care unit (ICU). The incidence of VAP varies from 10% to 30% and crude mortality rates in VAP exceed 50% [4] . The attributable costs of VAP approach $20,000 as per western literature. A joint committee of the Ameri­can Thoracic society (ATS) and Infectious Diseases Society of America (IDSA) has defined the various terms associated with VAP. VAP refers to pneumonia that arises more than 48-72 hours after endotracheal intubation [4] . Hospital acquired pneumonia (HAP) is defined as pneumonia that occurs 48 hours or more after admission, which was not incubating at the time of admission. Healthcare-Associated Pneumonia (HCAP) includes any patient who was hospitalized in an acute care hospital for two or more days within 90 days of the infection 4 . VAP is caused by a diverse range of patho­gens. The microbiological profile of VAP varies across ICUs and hospitals. Pseudomonas aeruginosa and Sta­phylococcus aureus occur with similar frequency and when pooled account for nearly 30% of all cases of VAP [4] . VAP is typically categorized as early-onset VAP (occurring in the first 3-4 days of mechanical ventila­tion) and late-onset VAP (> 5 days). Early-onset VAP is commonly caused by antibiotic-sensitive community­acquired organisms (e.g., Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus). Late-onset VAP is commonly caused by antibiotic-re­sistant nosocomial organisms (e.g., Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, Acinetobacter species, and Enterobacter species) [4] .

VAP develops from aspiration of oropharyngeal secretions containing potentially pathogenic organisms, aspiration of gastric secretions and mechanical ventila­tion a major risk factor. Pugin and colleagues devel­oped Clinical Pulmonary Infection Score (CPIS) as a diagnostic tool for pneumonia [3] . Mean score for pa­tients with confirmed VAP was 6.5 for unconfirmed cases CPIS was 5.9.

The laboratory diagnosis for confirmation includes microbiological examination of endotracheal aspirate (EA) specimen, Blind protected telescoping catheter (PTC) sampling and BAL (bronchoalveolar lavage) [5] . Difficult weaning is a term reserved for patients who fail initial weaning and require up to three spontaneous breathing trials (SBT) or as long as 7 days from the first SBT to achieve successful weaning [6] . Sixth Inter­national Consensus Conference on Intensive Care Medicine stated that pressure support or assist-con­trol ventilation modes should be favored in patients fail­ing initial trial/trials.

Adaptive support ventilation (ASV) is a micro­processor-controlled mode (closed loop ventilation) of mechanical ventilation that maintains a predefined minute ventilation and an optimal breathing pattern (tidal volume and rate) by automatically adapting inspiratory pressure and ventilator rate to changes in the patient's condition [1] . When ASV was used on passive patients with different respiratory system mechanics (normal lungs, restrictive disease, or obstructive disease), the ventilatory pattern applied by the automatic controller was markedly different: frequency and I:E ratio were adapted as expected, according to the type and sever­ ity of the respiratory disease [1] .Adaptive Support Ven­tilation has been studied as the sole mode of ventilatory support in chronically ventilated patients and has been shown to be cost effective with minimal settings required to be altered for accomplishment of effective weaning process [7] . ASV has the capability to adjust automati­cally to the patients ventilatory requirements by select­ing different VT-RR combinations based on respira­tory mechanics in passive, mechanically ventilated pa­tients [8] and hence can be successfully applied to any subset of patients. The improved respiratory mechan­ics even allow for fast tracheal extubations in post car­diac surgery patients [9] . To conclude, VAP is a fatal nosocomial infection which besides antibiotic cover and supportive measures requires lung protective advanced mode of ventilation which can be provided by effec­tively by ASV.



 
   References Top

1.Camargo LFA, DeMarco FV, Barbas CSV etal. Ventilator associated pneumonia: comparison between quantita­tive and qualitative cultures of tracheal aspirates. Criti­cal Care 2004, 8:422-430.  Back to cited text no. 1      
2.Brunner JX, Iotti A. Adaptive Support Ventilation (ASV). Minerva Anestesiol 2002;68:365-8.  Back to cited text no. 2      
3.Pugin J, Auckenthaler R, Mili N, Janssens JP, Lew PD, Suter PM. Diagnosis of ventilator-associated pneumo­nia by bacteriologic analysis of bronchoscopic and nonbronchoscopic "blind" bronchoalveolar lavage fluid. Am Rev Respir Dis 1991;143:1121-9.  Back to cited text no. 3      
4.American Thoracic Society; Infectious Diseases Soci­ety of America. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med 2005;171: 388-416.  Back to cited text no. 4      
5.Muscedere J, Dodek P, Keenan S, Fowler R, et al. Com­prehensive evidence-based clinical practice guidelines for ventilator-associated pneumonia: Diagnosis and treatment. Jr of Critical Care 2008; 23:138-147.  Back to cited text no. 5      
6.Boles JM, Bion J, Connors A, et al. Weaning from me­chanical ventilation. Eur Respir J 2007; 29: 1033-1056.  Back to cited text no. 6      
7.Linton Dm, Renov G, Lafair J, Vasiliev L, Friedman G. Adaptive support ventilation as the sole mode of venti­latory support in chronically ventilated patients. Criti­cal Care and Resuscitation 2006; 8: 11-14.  Back to cited text no. 7      
8.Arnal JM, Wysocki M, Nafati C, Donati S, Granier I, Corno G, Gasselin JD. Automatic selection of breathing pattern using adaptive support ventilation. Intensive Care Med 2008;34:75-81.  Back to cited text no. 8      
9.Christopher S, Rene C, Pierre-Guy C, Xavier M, Jean­Pierre R. Adaptive support ventilation for fast tracheal extubation after cardiac surgery: A Randomized Con­trolled Study. Anesthesiology 2001;95:1339-1345.  Back to cited text no. 9      


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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