a diagnostic examination, enhances the blunt dissection and can potentially break down locu lations, if present. Take hold of the drain tip with the forceps by placing them in through the distal side hole and out through the end hole. Prior to drain insertion consider disco nnecting the patient from any positive pressure ventilation to reduce the chance of intrapu lmonary lung placement. Gently insert the drain with the forceps and release. Try to positi on the drain apically for a pneumothorax and posterior-basally for \202 uid. Be cautious of intrapulmonary and mediastinal drain place- ment. To ensure adequate position and to obt ain any desired specimens, aspirate using a bladder-tipped syringe and/or connect to an und erwater sealed drainage bottle. Suture one end of the incision and place an anchoring sutur e around the drain. Avoid purse string sutures and use mono \201 lament suture material. P ad and stick to the skin using a small dressing, ensuring that the drain will not kink. One possible technique is to stick the drain in line with the ribs directed anteriorly. Removal Remove the drain as soon as it is no longer required or has failed. Close the drain site with a suture if required. If there continues to be a leak through the drain site, pl ace a stoma bag over it. If this fails to contain the situation, then either insert a new d rain or seek surgical advice. Complications \200 Bleeding from an intercostal vessel or a damaged viscous/organ. This is rare, but can be fa tal. Trauma to lung (including formation of bronchopleural fistula), heart, liver, spleen o r kidney. Again serious trauma is rare, but can be fatal. Infection: from super \201 cial drain site infection to empyema and lung abcess. Management Following insertion, obtain a CXR to assess the position. If functionally inadeq uate, regardless of radiological posi- tion, manipulate the drain accordingly or remove and , if necessary, re-insert. In dif \201 cult circumstances, seek radio- logical advice and consider CT guidance or thoracic surgi- cal assistance. Draining \202 uid off at too high a rate can result in re-expansion pulmonary oedema. This is rare, especially in patients r eceiving positive pressure ventilation. The risk can be minimized by limiting drainage to a maximum of 1500ml/h by clamping the drain. In all other instances, clamping of the Further reading Bouhemad B, Zhang M, Lu Q, et al. Clinical review: bedside lung ultrasound in critical care practice. Crit Care 2007; 11: 205. Laws D, Neville E, Duffy J, et al. BTS guidelines for the insertion of a chest drain. Thorax 2003; B Suppl 2: ii53 \200\2239. 40 J BALL Pleural aspiration Insert the needle/cannula, whilst aspirating using a syringe, until air/fluid is freely wit hdrawn. Having entered the pleural space, if there is a signi \201 cant volume of air/ \202 uid to be aspirated, attach a 3-way tap on a short extension to facilitate syringe cha nge over. If no \202 uid/air is aspirated, remove the needle/cannula and re-image with ul trasound. If necessary, reposition the patient. For a simple pneumothorax, aspirate as much air as possi- ble, making note of the volume. If, having drained 1000ml, air is still free ly aspiratable, consider inserting a pleural drain. If in doubt, re-image with X-ray or ult rasound. For a pleural effusion, aspirate suf \201 cient \202 uid for all diag- nostic t ests. Continue to aspirate further \202 uid if there is a significant residual volume. Me asure the total volume removed and be conscious of the possibility of re-expan- sion pulmon ary oedema. Once completed, remove the needle/cannula and cover the puncture site with a si mple dressing if required. If \202 uid starts to leak through the puncture site, cover wi th a small stoma bag or consider inserting a drain. Pleural aspiration or thoracocentesis is the removal of air or \202 uid from the pleural space (see also Chapter 1.17). Indications \200 \200 \200 Diagnosis of the nature of a pleural effusion Treatment of a simple pneumothorax Treatment of pleural effusion of suf \201 cient size to impair or compromise respiratory mechanics T reatment of an empyema Equipment preparation Depending upon the size, site and anticipated nature of the pleural c ollection, select an appropriately sized needle or cannula. This procedure should always be performed with strict adherence to aseptic precautions. Suggested items: \200 \200 \200 \200 \200 Bedside ultrasound 2% chlorhexidine-based skin cleaning \202 uid and reservoir. Sterile g auze Local anesthetic, syringe and needle. Chosen needle/cannula, t3-way tap on a short ext ension, an appropriately sized syringe for sampling/aspiration (20 \200\22360ml). Sterile s ample pots, blood gas syringe, glucose testing strip or blood glucose ( \202 uoride) sampl e bottle, blood culture bottles (aerobic and anaerobic), blood chemis- try/enzyme assay sam ple bottle Small dressing Specimens For microbiology, send raw \202 uid for microscopy, culture and sensitivities. If suspicious, also request staining and culture for mycobacteria. To increase the sensitiv ity of bacterial culture, inoculate a set of blood culture bottles with 10ml of \202 uid per bottle. Unless the \202 uid is frankly purulent, take a specimen in a blood gas syrin ge and put it through a blood gas analyzer to measure the pH. A pH <7.20 is consistent with an empyema and probably the most sensitive test. The two other assays consistent with this diagnosis is a \202 uid glucose of <3.35mmol/l and/or a lactate dehydrogenase level >3 t imes the upper limit of normal for serum. Determination of the fluid total protein to estab lish whether the effusion is a transudate or exudate is not of any great value and is unrel iable in diagnosing empyema. Patient preparation Whenever practical, inform the patient regarding the proposed procedure and gain their consent. Position the patient such that they are comfortable and the area i n which the procedure is to be performed is easily accessible and, for fluid collections, i s gravitationally dependent. This may be dif \201 cult in sedated and intubated patients o n positive pressure ventilation. Sitting the patient in as near an upright posture as possi ble with unhindered access to the posterior and/or lateral chest walls is ideal. Ensure tha t whatever the position, the operator is in an ergonomic position with access to the equipm ent. Complications and their management The most common complication of pleural aspiration is a small pneumothorax. This requires no action other than vigilance for increasing size, which is rare unless the lung has been punctured. If this has occurred, it is usually obvi- ous, as air is unexpectedly aspirated during the procedure. The risk of an enlarging.significan t pneumothorax is increased if the patient is on positive pressure ventilation. Under these circumstances, watch for an evolving tension pneumothorax and be prepared for immediate de com- pression and chest drain insertion. The second most common complication is damage to t he intercostal neurovascul;ar bundle. To avoid this, use the superior border of the rib as the landmark for the punc- ture site and maintain an insertion angle that minimizes the ris k of damage to the bundle associated with the rib above. Be aware that damage to the interc ostal artery can result in a signi \201 cant haemothorax and require surgical ligation. Procedure Though not obligatory, it is undoubtedly best practice to perform a thoracic ultr asound immediately prior to aspiration to de \201 ne the anatomy and avoid visceral injury . When aspirating small or complex collections, continuous ultrasound guidance is essential . For further information on thoracic ultrasound, see Bouhemad et al. (2007). A classic ima ge of a signi \201 cant pleural effusion is shown in Fig. 1.18.1. Clean the area and apply sterile towels. Infiltrate a small volume of local anesthetic into the subcutaneous and in tradermal spaces, avoiding the neuro- vascular bundle which runs along the inferior border of the rib. 41 CHAPTER 1.18 Pleural aspiration Fig 1.18.1 Ultrasound still image demonstrating a 4.04cm rim of pleural \202 uid between the chest wall (apex of image) and underlying consolidated lung. The value of ultrasound as sessment and, where necessary, ultrasound guidance in pleural aspiration cannot be overstat ed. Further reading Bouhemad B, Zhang M, Lu Q, et al. Clinical review: bedside lung Puncture of and/or damage to adjacent structures is easily avoided by ultrasound guidance. There are case reports of serious complications from pleural aspiration procedures in which the liver, spleen, kidneys, diaphragm and myocar- dium have been injured. Such iatrogenic injuries are rare with this procedure but have a signi \201 cantly higher incidence associ ated with pleural drain insertion. ultrasound in critical care practice. Crit Care 2007; 11: 205. Light RW. Parapneumonic effusions and empyema. Proc Am Thorac Soc 2006; 3: 75 \200\22380. 42 J BALL Flexible bronchoscopy Patient preparation Whenever practical, inform the patient regarding the pro- posed procedu re and gain their consent. Depending upon the indication, likely duration and clinical cond ition of the patient, an appropriate plan regarding topical anesthesia, sedation and neurom uscular blockade should be made. At a minimum, continuous ECG and SpO2 monitoring together with intermittent, automated non-invasive blood pressure should be used. The FiO2 should be increased to 100% (or as high as possible). If ventilated, a pressure con- trol mode is pr eferable although a strictly pressure-limited volume control mode can be used. Hypoventilat ion is an inevitable occurrence during the procedure. In patients in whom even transient hy percapnia needs to be avoided, a series of timed, short bronchoscopies can usually be safel y performed. In such circumstances, continuous end-tidal capnography is essential. Alternat ively, consider using HFV. Flexible bronchoscopy is an essential diagnostic and thera- peutic procedure in the ICU. Th e majority of procedures are performed in intubated patients receiving mechanical ventilati on. ICU indications \200 Direct visualization of the upper airway in difficult endotracheal intubation. Direct endot racheal visualization and guidance during percutaneous tracheostomy. Inspection of the dist al portion of an endotracheal or tracheostomy tube to assess patency and position. Inspecti on of the distal trachea and proximal bronchial tree for mucosal pathology/extrinsic compre ssion. Removal of material obstructing one or more major bronchi. Performing sampling of di stal airways for microbiological and/or cytological specimens. Guiding the placement of an endobronchial blocking/ isolation catheter. Procedure Before starting, ensure all necessary equipment is available and working, the pat ient is comfortable and the broncho- scopist is ergonomically positioned. Consider slowly i njecting 3 \200\2235ml of sterile saline into the endotracheal/ tracheostomy tube to lubric ate the passage of the scope. At least one assistant must be present to watch the patient, the ventilator and the monitoring, in addition to being able to assist the bronchoscopist. First navigate the endotracheal/tracheostomy tube and ascertain whether the tube is encrust ed with secretions. If so, this may both inhibit the procedure and present the patient with unwanted additional resistance. It may be pos- sible to clean the tube effectively using t he scope; however, electively changing the tube is usually preferable. Next, consider wheth er the tube opens centrally within the trachea and is a suf \201 cient distance from the m ain carina. If this is not so, reposition the tube under bronchoscopic guidance and make no te of the optimal position using the visible reference markers on the tube. Always consider whether moving the patient will adversely affect the position of the distal end of the tub e, and leave a detailed description in the patient \200\231s notes. Then go on to examine t he distal trachea, in particular, looking for mucosal trauma caused by the distal tip of th e tube and blind suction catheter insertion. Continue by inspecting the remainder of the ac cessible bronchial tree in a logical order. It should be possible to visualize the \201 r st 2 \200\2235 divisions of each lobar bronchus. For visible secretions, try to sample/remo ve without causing trauma to the mucosa and without using saline lavage. If required, colle ct a specimen for microbiological examina- tion. Dif \201 cult to clear secretions can oft en be removed piecemeal. Large pieces can often be held against the tip of the scope by app lication of continuous suction. The scope, together with the offending mass, can then be re moved en masse, by slowly withdrawing the scope whilst maintain- ing suction. Obstructing a ggregations of inspissated secretions, blood clots or mucosal sloughing may require prolong ed or multiple procedures. The use of biopsy forceps and cytology brushes may be useful but require Equipment preparation and aftercare Prior to use, the bronchoscope should be thoroughly cle aned and disinfected. Cross-infection between patients is a serious hazard. If stored, this should be in a dedicated clean environment. The scope should be handled aseptically and tr ansported in an appropriate enclosed container. All the remaining equipment should be clean or sterile single use. Essential equipment: \200 \200 \200 \200 \200 \200 \200 \200 \200 \200 Light source Camera/videoscope stack (optional) Cleaning brush for working channel A packet of sterile gauze A sterile 1 liter jug. A 500ml bag of 0.9% sodium chloride A 20ml syringe Sputum traps Dedicated suction A bronchoscopy catheter mount The scope should be checked for clear vision and a function- ing suction system immediately prior to use. The outside of the scope should be wiped with saline-soaked gauze. Avoid wat er-based gel lubricants as these can dry out and become sticky rather that lubricate. In si tuations where there is problematic sticking of the scope to the inside of an endotracheal or tracheostomy tube, use sterile liquid paraf \201 n. The bronchoscopist and any assistan ts should wear full protective clothing including gowns, gloves and face/eye cover. Appropr iate and sensible precautions should be made regarding the potential aerosolization of infe cted material. At the end of the procedure, the suction channel of the scope should be imme diately brushed through and then rinsed. The outside of the scope should be cleaned. The sc ope should then be sent for full decontamination. Any other reusable equipment should be cl eaned and stored appropriately. 43 CHAPTER 1.19 Flexible bronchoscopy airway secretions. It is worth discussing the optimal handling of specimens with the labs r eceiving them, in particular if qualitative or semi-quantative microscopy are required or s peci \201 c pathogens are suspected. If a good quality, large volume specimen is obtained, this can often be divided in the laboratory for both microbiological and cytological exami nation if required. This prevents repeated saline lavage and scope trauma, both of which ar e injurious Blind brush specimens may be useful in both cytological and microbiological tes ting. Brush and biopsy specimens of visible lesions can also be taken. In patients receivin g positive pressure ventilation, transbronchial biopsy and transbronchial needle aspiration specimens carry a signi \201 - cant risk of pneumothorax and pneumomediastinum and are be st avoided. Protected lavage and brush catheters are available, but are of questionable val ue. There is con \202 icting evidence regarding the value of bronchoscopic specimens over and above those obtained by blind endotracheal suctioning, most especially in the diagnosis of ventilator-associated pneumonia. skill and patience. Should \202 exible bronchoscopy fail, con- sider using a rigid scope. Nebulized 0.9% saline, 3% saline, N-acetyl cysteine (10 \200\22320%), unfractionated hepar in (10 000 \200\22325 000IU 4 \200\22312 hourly), 4.2% sodium bicarbonate and dornase alfa have all been described as useful adjuncts, but none has been proven to have superior ef \201 cacy over the others in ventilated patients. There is also no evidence to suggest a su perior ef \201 cacy for direct instillation vs nebulization. For visible mucosal bleeding, haemostasis will usually occur spontaneously. Haemostasis can be augmented by topical vaso constriction using adrenaline (epinephrine). Gently instill/irrigate with a 1 in 10 000 (0. 1mg/ml) solution. Topical anti \201 brinolytics, such as neat tranexamic acid (100mg/ml) c an also be useful. If the bleeding is distal to the main carina and unstoppable and/or dist al to the limit of visualization, temporary isolation and tamponade can be achieved by wedg ing the tip of the bronchoscope into the origin of the identi \201 ed bronchus. The ef \201 cacy of instilling vasoconstrictors and/or antifibrinolytics is uncertain. The value o f prolonged continuous suction is also debatable. If this fails to achieve haemostasis, the n a balloon-tipped bronchial isolation catheter can be inserted parallel to the bronchoscop e, which can then be used to guide catheter placement. This can be a dif \201 cult procedu re due to the aerosolization of blood within the airway masking any vision. Be careful not to dislodge the blocking catheter when withdrawing the scope. Consider paralyzing the patie nt and applying a high level of PEEP. If practical, turn the patient bleeding side down. As a further adjunct, connect and instill oxygen through the bronchoscope suction channel at a high \202 ow rate. De \201 nitive treatment for persistent hemorrhage is either select ive bronchial angiography and embolisation or surgery. Complications The following complications can occur and should be prepared for: \200 Displacement of the endotracheal/tracheostomy tube out of the trachea. Obstruction of the e ndotracheal/tracheostomy tube. Obstruction of the trachea or major bronchus Hypoxia/derecru itment/increasing ventilatory require- ments post-procedure Hypercapnia/underventilation Co ughing Bronchospasm Hemorrhage Pneumothorax Pneumomediastinum Sepsis secondary to transloca tion (bacteraemia) (see Yigla et al., 1999) Hypo- or hypertension/cardiac arrhythmias \200 \200 \200 \200 \200 \200 \200 \200 Specimens Whenever possible, send undiluted secretions for micro- biological investigation. To obtain a specimen from a region of interest beyond visualization, \201 rst locate the nearest lobar, segmental or subsegmental division, then gently wedge the tip of the bronch oscope into it. Before any sampling, ensure that the suction channel is clear of any proxim al secretions, which might contaminate the specimen. This may require the scope to be fully with- drawn, the channel cleaned with a brush and rinsed with clean saline, and the scope reinserted and positioned. Next, apply the specimen trap as close to the broncho- scope as possible. Slowly instill 20 \200\22360ml of 0.9% sterile saline, wait for a few seconds, th en apply continuous suction. If the airway completely collapses, ask an assistant gently to turn the strength of the suction down until some \202 uid is drawn into the specimen tra p. When no further \202 uid \202 ows, slowly withdraw the scope whilst maintaining cont inuous suction. Make a note of the volume instilled and the volume of the specimen. Examine the specimen for adequacy, looking for the presence of mucoid or infected Further reading BTS. British Thoracic Society guidelines on diagnostic \202 exible bron- choscopy. Thorax 2001; 56 Suppl 1: i1 \200\22321. Ernst A, Silvestri GA, Johnstone D, et al. Interventional pulmonary procedures: guidelines from the American College of Chest Physicians. Chest 2003; 123: 1693 \200\223717. Mehta AC, Prakash UB, Garland R, et al. American College of Chest Physicians and American A ssociation for Bronchology [corrected] consensus statement: prevention of flexible bronchos copy- associated infection. Chest 2005; 128: 1742 \200\22355. Yigla M, Oren I, Bentur L, et al. Incidence of bacteraemia following \201 breoptic bronchoscopy. Eur Respir J 1999; 14: 789 \200\22391. 44 M NORRENBERG Chest physiotherapy and improve ventilation for patients with reduced inspira- tory volumes, e.g. following sur gery. Expiratory breathing techniques (forced expirations, huf \201 ng and coughing) are u sed to increase expiratory flow rates and, thereby, enhance airway clearance and mobilize s ecretions from the peripheral to upper airways. Thus, expiratory breathing exercises may ne ed to be accompanied by interventions that increase inspiratory volume, if reduced inspirat ory volumes are contributing to an ineffective cough. To evacu- ate the sputum, physiothera pists help the patient with cough techniques or perform tracheal suctioning. Forced expirat ory maneuvers should be used with caution in patients with bronchospasm, to avoid exacerbat ion of spasm, or cardiac dysfunction. Critical illness is associated with high morbidity and mor- tality rates, and the associate d care is a major determinant of healthcare costs. Critically ill patients cared for on the ICU can have prolonged periods of immobility, with critical illness lasting from hours to months, depending on the underlying pathophysiology and the patient \200\231s response to t reatment. Respiratory dysfunction is one of the most common causes of critical illness nece ssitating ICU admission. The aims of chest physiotherapy (CPT) are to clear secretions, to pre- vent pulmonary complications, to improve ventilation and/ or regional ventilation and lung compliance, and to reduce airway resistance and the work of breathing. CPT in mechanically ventilated patients Such patients are especially at risk of complicatio ns. They are generally sedated, with an arti \201 cial airway and some- times inadequate h umidi \201 cation. These three components alter mucociliary clearance. Instrumental techniques Manually assisted cough, using thoracic or abdominal com- pression, may be indicated for patients with expiratory muscle weakness or fatigue (e.g. neuromuscul ar conditions) An inspiratory/expiratory insuf \202 ator is a device that delivers inspira tory pressure followed by a high negative expiratory force, via a mouthpiece or face mask. It is indicated when a patient is unable to clear secretions using other interven- tions. I t has been applied with success in the management of patients with retained secretions seco ndary to respira- tory muscle weakness (e.g. muscular dystrophy). Incentive spirometry (IS) can be used to encourage improved lung volumes and \202 ow rates. IS is believed to impr ove the distribution of ventilation by increasing lung volumes and encouraging prolonged sl ow inspiration. IS may be pre- scribed for patients after major surgery to either prevent o r treat post-operative pulmonary complications; however, it has not been shown to be of add ed bene \201 t (beyond body position and early mobilization) in the management of routine post-operative patients. An intrapulmonary percussive ventilator (IPV) is a mode of ventila tion that can be used in the management of intu- bated or non-intubated patients using a mo uthpiece. IPV is believed to increase mucociliary clearance. A recent review has shown that this technique has no effect on sputum weight, mucociliary transportation or pulmonary fun ction. Adverse effects include bronchospasm, haemoptysis, hypoxaemia and bradycardia, thus appropriate monitoring is indicated. Positive expiratory pressure (PEP) refers to a device to aug- ment oxygenation and airway clearance in non-intubated patients and can be applied with a face mask or mouth- piece. PEP is used mostly for medical patients with exces- sive airway secretions (e.g. cystic \201 brosis). PEP in critical care could assist in secreti on removal in COPD patients requiring NIPPV. Flutter valve device. The Flutter valve is contained within a pipe-shaped device with an opening at the mouthpiece and small outlets at the top of the bowl. As the patient exhales, a steel ball is displaced, generating PEP a nd oscil- lating waves of pressure within the airways (high-frequency oscillations). The Fl utter device is indicated in spontane- ously breathing patients who have excessive airway secretions (e.g. cystic \201 brosis). The role of the Flutter device in critically ill patients has not been studied, but may be limited by the patient \200\231s capacity to coo perate. Increase of expiratory \202 ow CPT maneuvers involve inspiratory and expiratory tech- niq ues, with and without the aid of positive pressure devices. The physiotherapist applies ext ernal forces during expiration, inducing an increase in expiratory \202 ow and therefore an increase in mucus transportation. These techniques of increased expiratory \202 ow can be used passively in venti- lated, sedated patients or actively in more alert, coopera- ti ve patients. Patients are often placed in the lateral decubitus position for these maneuver s. To evacuate the sputum, physiotherapists perform tracheal suctioning. Some may also add manual hyperin \202 ations, manual vibra- tions, etc. Manual hyperin \202 ation (MHI) or ventilator hyperin \202 ation (VHI) The aims of hyperi n \202 ation are to prevent pulmonary atel- ectasis, re-expand collapsed alveoli, improve oxygenation, improve lung compliance and facilitate movement of pul- monary secretions towa rds the central airways. MHI is per- formed by delivering a large tidal volume combined wit h an expiratory plateau and a fast release of the resuscitator bag. The quick release of th e bag enhances expiratory \202 ow and mimics a forced expiration. MHI can result in marke d haemodynamic changes associated with a decreased car- diac output, which result from larg e fluctuations in intrathoracic pressure. A pressure of 40cm H2O has been recommended as an upper limit. MHI can also ICP and mean arterial pressure (MAP) which has implications for patients with brain injury. These increases are usually lim- ited, however, so that the cer ebral perfusion pressure com- monly remains stable. Prevention of pulmonary complications in mechanically ventilated patients In mechanically v entilated patients there is a decrease in VAP in patients treated with physiotherapy and st andard nursing care in comparison with those managed with standard nursing care alone. CPT in patients without endotracheal intubation Breathing exercises Inspiratory breathing e xercises coupled with mobilization and body positioning are used to increase lung volumes 45 CHAPTER 1.20 Chest physiotherapy suf \201 cient to elicit acute physiological effects that enhance ventilation, central and peripheral perfusion, circulation, muscle metabolism and alertness. Respiratory muscle training Comparably with other skeletal muscles, respiratory mus- cles c an be trained to enhance contraction performance (force, endurance, velocity of shortening and metabolic ef \201 ciency). Because ventilatory failure can be related to respiratory m uscle dysfunction, improving the function of the respiratory muscles is a rational treatmen t goal. Recent uncontrolled trials of inspiratory muscle training in criti- cally ill patie nts suggest that it improves inspiratory muscle function and, hence, may contribute to succ essful weaning. Conclusions CPT clears secretions, prevents pulmonary complications, and improves ventilati on and lung compliance. Physiotherapists must choose their therapeutic interven- tions as a function of a preliminary clinical examination to be sure that their treatment will be the rapeutic and safe. Unstable patients should be monitored continuously dur- ing physiotherap y. Finally, physiotherapists can contribute to the patient \200\231s overall well-being by providing emotional support and enhancing communication. Positioning Patient positioning can be used to increase gravitational stress and associated \202 uid shifts, through head tilt and other positions that approximate the upright posi tion. The upright position increases lung volumes and gas exchange, stimulates autonomic ac tivity and can reduce cardiac stress from compression. The semi-recumbent, prone and latera l position are used, respectively, to decrease the risk of nosocomial pneumo- nia, and to i mprove gas exchange in ARDS and in unilateral lung disease. It has been suggested that good positioning combined with CPT in the treatment of acute lobar atel- ectasis is as effectiv e as \201 breoptic bronchoscopy. Further reading Denehy L. The use of manual hyperin \202 ation in airway clearance. Eur Respir J 1999; 14: 958 \200\22365. Devroey M. Percussion intrapulmonaire: une aide pour le kin si- th rapeute? In: Actualit s en kin sith rapie de r animation. Elsevier,2000; 74 \200\2237. Gosselink R.K, Schrever P, Cops H, et al. Incentive spirometry does not enhance recovery af ter thoracic surgery. Crit Care Med 2000; 28: 679 \200\22383. Martin AD, Davenport PD, Franceschi AC, et al. Use of inspiratory muscle strength training to facilitate ventilator weaning: a series of 10 consecutive patients. Chest 2002; 122: 192 \200\2236. Mobilization Although part of physiotherapy, mobilization cannot be included as part of CPT , but it can in \202 uence ventilation and can play a role in pulmonary complications. Mob ilization has been part of the physiotherapy management of acutely ill patients for several decades and refers to physical activity Stiller K. Physiotherapy in Intensive Care. Towards an evidence based practice. Chest 2000; 118: 1801 \200\22313. Van der Schans CP, Postma DS, Koeter BK. Physiotherapy and bron- chial mucustransport. Eur Respir J 1999; 13: 1477 \200\22386. 46 M NORRENBERG Humidi \201 cation Introduction Water vapor is contained in the air and its amount is in \202 uenced by atmos pheric conditions. While the normal temperature of the atmosphere never reaches the boiling point of water (100 C), variation in air temperature is certainly the most important para meter in \202 uencing water vapor content. Water vapor capacity is the maximum amount of w ater that a gas can hold at a particular tem- perature. Two other concepts are important co ncerning water vapor content: one is the absolute humidity (AH) de \201 ned as the weight of water vapor contained in a given volume of gas. The second is the relative humidity (RH) , de \201 ned as the relationship between the content of water in air at a speci \201 c t emperature and the capacity of water that air can hold at the same temperature RH = (conten t/capacity) \227 100 breathing circuit). An ideal system generates the required amount of humidity, in the form of water vapor, at the correct temperature, and transports it to the patient without the lo ss of either heat or moisture. The most effective way to achieve this is to use a large hea ted water surface for the generator, and heating ele- ments within the delivery system to p revent condensation. There are three types of active humidi \201 ers: Bubble: unheated hum idi \201 ers most generally dedicated to simple oxygen therapy. At body temperature, the R H of the inspired gas never exceeds 40%. Humidi \201 cation with this device is a function of the temperature in the room, the volume of water in the humidi \201 er and the gas \202 ow (most ef \201 cient with \202 ows <5l/min). Passover and wick: these two heated humidifiers are used for patients being treated by mechanical ventilation. They are designe d to bring the gas in the airways to a temperature between 34 and 37 C with an RH of 100%. Nevertheless, ventilatory settings may influence the humidity of the inspired gas. Condens ation in ventilator circuits is limited by using heated circuits. Humidi \201 cation during spontaneous breathing and mechanical ventilation With natural ai rways The upper airways ensure that inspired gasses are heated or cooled to body temperatur e (37 C) and humidi \201 ed to an RH of 100% at body temperature. More speci \201 cally , when inspired gasses arrive at the con- chae, turbulent \202 ow is created. The archite cture of the conchae consists of three turbinates covered by a folded mucous membrane, repr esenting a volume of only 20ml but a surface area of 160cm2. Therefore, each gas molecule i s likely to come into contact with the surface area of the vascular nasal mucous membrane. The moist mucous membrane heats inspired gasses to body temperature and, producing up 650 \200\2231000ml of H2O per day, brings inspired gasses to an RH of 80% on leaving the nose t o enter the nasopharynx. Mucus produced in the nasal cavity is also responsible for the hum idi \201 cation of inspired gasses Heat and moisture exchangers (HMEs) This system, which is placed close to the patient at th e end of the dead space, preserves the water vapor contained in the gas exhaled by the pati ent. During the subsequent inspiration, the water maintained in the HME is used to humidify the inspired gas. There are two types of HME: hygroscopic and hydropho- bic. The ef \201 ciency of these two types of HME is quite simi- lar, close to 70%. Hydrophobic HMEs can \201 lter bacteria. Contraindications of HME \200 \200 Thick, copious or bloody secretions Leaks in the circuit creating an expired tidal volume < 70% of the inspired tidal volume. Patients with a body temperature <32 C High minute volum es (>10l/min) With arti \201 cial airways The gas arriving from the ventilator is cold (15 C) and dry ( 2% RH), and the ETT bypasses the physiological humidi \201 - cation and heating of inspire d gasses. Absence of humidi \201 ca- tion induces alterations in mucus transportation, dec reased mucus clearance, lesions of the epithelium and mucosa, and changes in ventilatory pa rameters (decreased compli- ance and functional residual capacity, increased resistance). T herefore, artificial devices must be installed during mechanical ventilation. There is a re lationship between air- way mucosal dysfunction and the combination of inspired gas humidit y and temperature with exposure time to a given humidity An arti \201 cial humidi \201 er replaces the humidifying function of the upper airways by increasing the water vapor conte nt of a dry gas. \200 Comparison between active and passive humidi \201 ers Le Bourdell s et al. observed a sig ni \201 cant decrease in alveolar ventilation with HMEs (as indicated by an increase in mi nute ventilation and respiratory rate, but an increase in PaCO2) in comparison with heated humidi \201 ers during weaning from mechanical ventilation in a pressure support mode. The se observations should be taken into account during dif \201 cult weaning . Other authors reached the same conclusions. HME sin- crease work of breathing (WOB), respiratory rate and minute ventilation in pressure support in comparison with heated humidi \201 ers. On the basis of these observations, one may recommend increasing the level of pressure sup- port ( by 5 \200\22310cm H2O) to maintain the WOB constant. For all these reasons, HME is not reco mmended for patients with COPD. In non-COPD patients receiving prolonged mechanical ventila tion, Ricard et al. compared a group of patients where the HME was changed every 48h with a group with a change after 7 days. There was no difference in resistance Humidi \201 ers There are two types of humidi \201 er: active and passive. Active humidi \201 ers add water vapor to inspired gasses, whereas passive humidi \201 ers exchange hea t and moisture by preserving the moisture and heat in the gas exhaled by the patient. Active humidi \201 ers Active humidifiers consist of a humidity generator (or water reserv oir) and humidity delivery system (or 47 CHAPTER 1.21 Humidi \201 cation During weaning from mechanical ventilation in pressure support mode and in NIV, HMEs are no t recommended because of increases in dead space, PaCO2 and WOB, unless one signi \201 can tly increases the pressure support level. Passive and active devices seem to be equivalent in terms of ef \201 cacy and prevention of infection. in the ETT or in infection, indicating that the HME can be changed only once a week, which represents a substantial cost saving. Nevertheless, few studies have studied the problem of the reduction in diameter of the ETT. Two different methods have been used (measurement of internal pressure and \202 ow along the tube, and an acoustic re \202 ection method), a nd both concluded that there was a progressive reduction in ETT patency with active and pas sive humidi \201 cation, but this occurred to a greater extent with HMEs than with active humidi \201 ers. The effect of these systems on the incidence of VAP is con- troversial. T hree recent reviews or meta-analyzes reached different conclusions: Ricard et al. and Ni l -Weise et al. concluded that the type of humidi \201 cation device does not in \202 uence the incidence of VAP. If an active humidi \201 er is used, Ni l-Weise et al. recommended using a heated wire circuit because less condensate reduces colonization. On the other han d, Kola et al. reported a signi \201 cant reduction in the occurrence of VAP with HMEs, pa rticularly for patients ventilated for >7 days, but they excluded patients at high risk of airway occlusion (COPD). Finally, in NIV, if humidi \201 cation is mandatory (i.e. with an ICU ventilator using cold and dry gasses), a heated humidi- \201 er is recommended over HMEs because HMEs decrease the bene \201 cial effects of NIV on WOB. Further reading Jaber S, Pigeot J, Fodil R, et al. Long-term effects of different humid- i \201 cation systems on endotracheal tube patency: evaluation by the acoustic re \202 ecti on method. Anesthesiology 2004; 100: 782 \200\2238. Kola A, Echmanns T, Gastmeier P. Ef \201 cacy of heat and moisture exchangers in preventin g ventilator-associated pneumonia: meta- analysis of randomized controlled trials. Intensiv e Care Med 2005; 31: 5 \200\22311. Le Bourdell s G, MierL, Fiquet B, et al. Comparison of the effects of heat and moisture ex changers and heated humidi \201 ers on ventila- tion and gas exchange during weaning trial s from mechanical ventilation. Chest 1996; 110: 1294 \200\2238. Ni l-Weise BS, Wille JC, van den Broeck PJ. Humidi \201 cation policies for mechanically ventilated intensive care patients and prevention of ventilator-associated pneumonia: a sys tematic review of rand- omized controlled trials. J Hosp Infect 2007; 65: 285 \200\22391. Ricard JD, Boyer A, Dreyfuss D. The effect of humidi \201 cation on the incidence of venti lator-associated pneumonia. Respir Care Clin N Am 2006; 12: 263 \200\22373. Ricard JD, Le Mi re E, Markowicz P, et al. Ef \201 ciency and safety of mechanical ventil ation with a heat and moisture exchanger changed only once a week. Am J Respir Crit Care Me d 2000; 161: 104 \200\2239. Conclusions Regardless of their type, humidifiers are essential for mechanically ventilated patients. For at risk patients (e.g. COPD, copious secretions, etc.), one may prefer activ e humidi \201 ers with heated wire circuits. Villafane MC, Cinnella G, Lofaso F, et al. Gradual reduction of endotracheal tube diameter during mechanical ventilation via different humidification devices. Anesthesiology 1996; 85 : 1341 \200\2239. 48 M PINSKY Heart \200\223lung interactions