This guidance does not override the individual responsibility of health professionals to make appropriate decision according to the circumstances of the individual patient in consultation with the patient and /or carer. Health care professionals must be prepared to justify any deviation from this guidance. INTRODUCTION This guideline covers the use of Volume Targeted ventilation for neonates requiring mechanical ventilation on the neonatal unit. This is a mode of ventilation which aims to reduce the risk of ventilator-induced trauma to the lungs by targeting a set tidal volume and limiting the maximum peak inspiratory pressure delivered. THIS GUIDELINE IS FOR USE BY THE FOLLOWING STAFF GROUPS : This Guideline is to be used by all qualified nurse practitioners, senior nursing staff and paediatric medical staff Lead Clinician(s) Dr Peter van der Velde Locum Consultant Paediatrician Approved by Quality Improvement Meeting on: 24 July 2015 This guideline should not be used after end of: 24 July 2017 Key amendments to this guideline Date Amendment Approved by: (name of committee or accountable director) WAHT-NEO-056 Page 1 of 8 Version 1
INTRODUCTION Preterm and term infants may require mechanical ventilation while on the neonatal unit for a number of reasons, including RDS, congenital pneumonia, systemic sepsis etc. Mechanical ventilation can induce lung injury, and is an important cause of morbidity and mortality in the neonatal period. Mechanisms of lung injury include barotrauma (pressure-induced), volutrauma (volume induced), atelectotrauma (due to alveolar collapse and re-expansion) and biotrauma (due to inflammation). Volutrauma is generally felt to be the most damaging. Excessive tidal volumes (TV) may occur with pressure controlled ventilation, where the ventilator is programmed to deliver a set peak inspiratory pressure. Volume Targeted ventilation (also called pressure control-volume guarantee (PC-VG) or volume controlled ventilation, with subtle differences depending on the ventilator manufacturer) aims to minimise the risk of lung injury by targeting a set TV, rather than pressure, while still limiting the maximum inspired pressure. In addition, decreasing TV fluctuations, and reducing variations in minute volume, leads to a more stable PaCO2 and less hypocarbia. Avoiding a very low TV may reduce risks of atelecto-trauma and hypercarbia. It is a modality which works very well in synchronous ventilator modes, such as SIMV, where the ventilator senses and supports the infants own breaths, and is already used extensively in neonatal units around the UK, and world-wide. A Cochrane review published in 2010, analysed 12 randomized trials comparing Volume Targeted ventilation (VTV) to traditional Pressure-Limited ventilation (PLV) in infants less than 28 days corrected age, and concluded that infants ventilated using VTV modes had reduced rates of death and chronic lung disease compared with infants ventilated using PLV modes. DETAILS OF GUIDELINE Tidal Volume refers to the amount of air that moves in and out of the chest, with each breath, during normal quiet respiration. While ventilated, this is the volume of air delivered into the lungs with each breath. This is dependant both on pressures delivered by the ventilator (PPeak and PEEP), and the compliance of the lungs and chest. For a given peak pressure, a ventilator will deliver a larger tidal volume to more compliant lungs. With traditional pressure-limited ventilation using a fixed inflation pressure, the tidal volume delivered can vary widely. With Volume Targeted ventilation the following are set : Tidal Volume (TV) PEEP Maximum allowed Positive Pressure (PMax) Backup rate Inspiratory time (Tinsp) fio2 The PPeak (Max pressure delivered) will be variable (up to the maximum allowed), and will be dependent on a number of factors, but mainly lung compliance. WAHT-NEO-056 Page 2 of 8 Version 1
ADVANTAGES OF VOLUME TARGETED VENTILATION Decreased risk of overdistension, and volutrauma, particularly after surfactant administration when compliance can fall rapidly Immediate response to sudden changes in compliance and resistance Automatic decrease of PPeak during weaning More stable tidal and minute volumes. VTV can be used in any neonate in whom pressure limited ventilation could be used. DISADVANTAGES OF VOLUME TARGETED VENTILATION To use VTV, it is necessary for the ventilator to determine the tidal volume with each breath, using a flow sensor, which measures both flow and volume, usually in exhalation for improved accuracy. If there is a large air leak around the tube, this measurement becomes inaccurate, and a set volume cannot be guaranteed for each breath. Leaks above 60% are particularly problematic, and may make VTV difficult. If the flow sensor becomes blocked/dirty with secretions, it may read incorrectly, and affect the pressures delivered. It should be removed during surfactant administration. SETTING UP VOLUME TARGETED VENTILATION This guideline will deal with the use of SIMV+PC-VG on the Engstrom Carestation. Other similar modalities are sometimes used (SIPPV, assist control, pressure support etc.), but for the sake of simplicity, will not be mentioned here. SIMV is a synchronised mode, which will support a number of breaths per minute equal to the backup rate, triggered by the baby. If the baby is breathing below the backup rate, extra, nontriggered breaths will be delivered. Spontaneous breaths above the backup rate will not be supported. With SIMV+VG, The ventilator will attempt to deliver the targeted tidal volume for all supported breaths, triggered or non-triggered. Infants can be converted from Pressure Limited Ventilation or started immediately on VTV. The below ventilator settings are a guide only, and individual settings should be considered on a case-by-case basis depending on the neonate, the pathology involved and response to ventilation. te Pmax is the maximum inspired pressure the vent is allowed to deliver. Ppeak is the actual maximum pressure delivered to achieve the desired TV. WAHT-NEO-056 Page 3 of 8 Version 1
Input patient weight, by going through system setup then patient setup. Select SIMV+PC-VG, by going through the Vent setup menu. Set initial TV 4-5 ml/kg (Avoid if possible TV <3.5ml/kg, or >8ml/kg) Set PEEP 4-6 cm Set Tinsp 0.35 s Set backup rate 45-60 bpm (or previous rate on PLV) Set the Pmax ~22 to 25 cm on a new infant, (or no more than 4 cm above the previous PIP if converting from PLV). Set fio2 as required to maintain targeted saturations. Start ventilating Observe the Ppeak required to deliver the set TV over the next few minutes If required TV is not achieved, it may be necessary to cautiously increase the Pmax Aim to set the Pmax ~20% above the observed Ppeak (ensure Pmax is not excessive) With SIMV, the PIP should wean automatically as lung compliance improves. If further weaning is required, reduce the rate in the first instance. With rates <30 bpm, consider dropping the TV by 0.5 ml/kg at a time, but avoid dropping below 3.5 ml/kg. ALARMS Low Tidal Volume (not achieving set TV ) Look for obstruction Consider air leak around ETT (may need to reposition/upsize tube) Ensure Tinsp is not too short Low minute Volume Minute volume is the amount of air delivered per minute (TV x Rate) Consider increasing rate or TV dependent on blood gas analysis Consider resetting minute volume alarm thresholds if gases and ventilator settings are acceptable should aim for 01.-0.45 l/kg/min High minute volume TV may be set too low for adequate alveolar ventilation, causing tachypnoea and raising the MV Water in the ventilator circuit can cause abnormal breath triggering, causing gas trapping May need to cautiously raise the trigger sensitivity if triggering too easily WAHT-NEO-056 Page 4 of 8 Version 1
REFERENCES Klingenberg C, Wheeler KI, Davis PG and Morley CJ.(2011) A practical guide to neonatal volume guarantee ventilation. Journal of Perinatology, 2011 Sep;31(9):575-85. doi: 10.1038/jp.2011.98. Epub 2011 Jul 14. McCallion N, Davies P. and Morley C.(2009) Volume Targeted versus pressure-limited ventilation in the neonate. The Cochrane Library (2009), Issue 1. Southern West Midlands Newborn Network; Staffordshire, Shropshire & Black Country Newborn and Maternity Network; Neonatal Guidelines 2013-2015 Neonatal Coordinating Group (2006): Volume guarantee ventilation & VIVE. Neonatology Clinical Care Unit Guidelines. King Edward Memorial/Princess Margaret Hospitals. Perth, WA. WAHT-NEO-056 Page 5 of 8 Version 1
CONTRIBUTION LIST Key individuals involved in developing the document Name Designation Dr Peter van der Velde Locum Consultant Paediatrician Circulated to the following individuals for comments Name Designation Consultant Paediatricians Heads of neonatal nursing Circulated to the following CD s/heads of dept for comments from their directorates / departments Name Directorate / Department Dr Andrew Gallagher Children s directorate Dr Andrew Short Divisional medical director Circulated to the chair of the following committee s / groups for comments Name Committee / group WAHT-NEO-056 Page 6 of 8 Version 1
Supporting Document 1 - Equality Impact Assessment Tool To be completed by the key document author and attached to key document when submitted to the appropriate committee for consideration and approval. Yes/ Comments 1. Does the policy/guidance affect one group less or more favourably than another on the basis of: Race Ethnic origins (including gypsies and travellers) Nationality Gender Culture Religion or belief Sexual orientation including lesbian, gay and bisexual people Age 2. Is there any evidence that some groups are affected differently? 3. If you have identified potential discrimination, are any exceptions valid, legal and/or justifiable? 4. Is the impact of the policy/guidance likely to be negative? 5. If so can the impact be avoided? 6. What alternatives are there to achieving the policy/guidance without the impact? 7. Can we reduce the impact by taking different action? If you have identified a potential discriminatory impact of this key document, please refer it to Human Resources, together with any suggestions as to the action required to avoid/reduce this impact. For advice in respect of answering the above questions, please contact Human Resources. WAHT-NEO-056 Page 7 of 8 Version 1
WAHT- This guideline has been printed from the Worcestershire Acute Hospitals NHS Trust intranet on 06/10/2015,12:32 It is the responsibility of every individual to check that this is the latest version/copy of this document. Supporting Document 2 Financial Impact Assessment To be completed by the key document author and attached to key document when submitted to the appropriate committee for consideration and approval. Title of document: 1. Does the implementation of this document require any additional Capital resources 2. Does the implementation of this document require additional revenue Yes/ 3. Does the implementation of this document require additional manpower 4. Does the implementation of this document release any manpower costs through a change in practice 5. Are there additional staff training costs associated with implementing this document which cannot be delivered through current training programmes or allocated training times for staff Other comments: If the response to any of the above is yes, please complete a business case and which is signed by your Finance Manager and Directorate Manager for consideration by the Accountable Director before progressing to the relevant committee for approval WAHT-NEO-056 Page 8 of 8 Version 1