Access GNS 320.pptx by Azi Bulus Samuel BNSc, MSc Pharm.

Access (invasive and non-invasive) in critical care setting

1. Critical Care nursing ACCESSES MED-SURG IV (GNS 320) By Mr. Azi B. S.

2. Accesses Venous accesses Arterial accesses Peripheral Venous A ccesses (PVC) also known as peripheral venous catheter positioning: antecubital fossa forearm dorsum of the hand external jugular vein Indication: Patients been monitored (unless there is already a CVC) no programmed regular replacements (only in case of signs of inflammation) special cases: dialysis patients needing resuscitation in emergency situation (at least not proximal of the shunt) however, the shunt may be punctured in dialysis patients in whom venous access is often difficult due to the mostly poor vascular status stroke patients: not into the paretic arm

3. S izes (G: Gauge) The achievable flow rate in a white PVC (17 G) is just as high as in a CVC (flow rate approximately 120 ml/ min), in a grey (16 G) and orange (14 G) PVC even higher so that in case of emergency one or more large PVCs are completely adequate for a rapid volume application (above all, loss of time due to the positioning of the CVC!).

4. PVC connected to an infusion should be saved in addition to a plaster with a cob rein which is sticked over a 10cm long loop of the infusion tube, in order to reduce the risk of dislocation. Ultrasound (linear array) can be very helpful to find a vein in the antecubital fossa or in the proximal upper arm (medial) if positioning of a PVC is not possible. The puncture can then be performed under sonographic view.

5. U ltrasound guided positioning of a PVC with the linear array probe in the proximal medial upper arm: good option in case of poor venous status in the emergency room or in the intensive care unit (there should always be an ultrasound device!)

6. Central Venous A ccess Def: is the positioning of catheter in the caval vein (superior or inferior) Flow rate: approximately 100-150 ml/min for polyurethane catheter coated with hydromer , and 300-400 ml/min for Shaldon catheter

7. L umens A single catheter incorporates separate, non-communicating access lumens within its body. CVCs may have a single lumen or multiple lumens (2-7 lumens). In ICU you should at least use triple-lumen catheters, especially in the internal intensive care medicine. Multiple lumens catheter are needed for the administration of catecholamines, parenteral nutrition or for advanced hemodynamic monitoring (e.g. PiCCO ) and or when the dwelling time of > 48 hours. A five-lumen CVC is not more expensive than a triple, but risk of infection increases with the number of lumens.

8. Multiple Lumen CVC Central V enous C atheters (CVC): triple-lumen Central V enous C atheters (CVC): five -lumen

9. Indications diagnostic: measurement of central venous pressure (CVP) in hemodynamic monitoring but not solely for CVP measurement. measurement of the central venous oxygen saturation (ScvO2) therapeutic: hyperosmolar solutions ( p.d. > 900 mosmol /l) parenteral nutrition - Administration of fats, amino acids and glucose up to a concentration of 10%. electrolytes (e.g. potassium) sodium carbonate chemotherapy catecholamine therapy long-term infusion therapy impossibility to place a peripheral venous access due to poor venous status

10. Central Venous Pressure (CVP) Def: CVP is a measure for the right ventricular end-diastolic pressure (RVEDP; filling pressure of the right ventricle) and thus a measure for the right ventricular preload. Normal value: 8-12 cmH 2 O (discontinuous measurement) 5-10 mmHg (continuous measurement 1 mmHg/1.36 cmH 2 O) The CVP corresponds to the filling pressure of the right ventricle. T ransmural pressure difference between the pressure inside and the outside of the superior caval vein Only the pressure on the inside can be measured. For the pressure on the outside the atmospheric pressure is taken as a surrogate parameter which is why a zero adjustment must be made.

11. Determinants of CVP The CVP depends on the following factors: intravascular volume status peripheral vascular tone right ventricular compliance pulmonary vascular resistance intrathoracic pressure (mechanical ventilation) inspiration → CVP ↓; if CVP ↑: Kusmaul sign (constrictive pericarditis, restrictive endocarditis) expiration → CVP ↑ Confounders: pleural effusion, increased intra-abdominal pressure, mediastinal edema) CVP only inadequately correlates with the preload.

12. Measurement discontinuous (connection of central venous catheter to a special infusion set connected to a diameter water column [method of water column; thorax-caliper]; method according to Burri and Perren) horizontal position hydrostatic zero point: right atrium at the height of the confluence of the coronary sinus alignment of the position of the zero point with the position of the right atrium (3/5 of the dorsoventral diameter); the pressure transducer must be positioned at the height of the right atrium: If it is placed too high, a too low CVP is measured if it is placed too low, a too high CVP is measured. The CVP changes by 1 cmH2O or 0.75 mmHg per cm of deviation from the zero point. only in spontaneously breathing patients (not in mechanically ventilated patients

13. Measurement continuous (electrically via transducer; pressure element; standard today) Wave form: waves (pressure increases in the right atrium): a wave: through contraction of the right atrium (a: a trial) high a wave: pulmonary hypertension (e.g. pulmonary embolism), tricuspid valve stenosis; even giant / cannon-a wave: AV dissociation (atrioventricular fusion: The right atrium contracts against the closed tricuspid valve which massively increases the pressure in the right atrium). several a waves: atrial flutter missing a wave: atrial fibrillation

14. Measurement c wave: contraction (c: c ontraction; other explanation: c losure of the tricuspid valve of the right ventricle which increases pressure in the right atrium. v wave: passive filling of the right atrium with closed tricuspid valve (influx of venous blood [v: v enous]); high v wave: severe tricuspid valve regurgitation, acute right-sided heart failure, pericardial tamponade descents (pressure drop in the right atrium)

15. Measurement: x-descent: pressure drop through downward movement movement of the valvular plane (displacement of the valvular plane), relaxation of the right atrium (x: rela x ation; filling of the right atrium) missing x-descent: atrial fibrillation flattened x-descent: tricuspid valve regurgitation (Mueller's sign: ventricularization of the CVP curve upon inspiration, i.e. the pressure curve of the CVP is similar to that of the right ventricle; typical for a severe tricuspid valve regurgitation; pressure may also increase upon inspiration [ Kusmaul sign]) y-descent: pressure drop through influx of blood from the right atrium to the right ventricle (relaxation of the right ventricle in the early diastole [y: earl y ]) deep y-descent: right-sided myocardial infarction, hypervolemia, constrictive pericarditis (typical M-configuration), restrictive cardiomyopathy flattened y-descent: pericardial tamponade, tricuspid valve stenosis

16. CVP pressure curve (pressure curve of the right atrium [RA]; normal finding) CVP pressure curve (RA pressure) in patient with atrial flutter: Several (and regular) a waves can be seen

17. CVP pressure curve: RA pressure in patient with atrial fibrillation: There is no a wave and no x -descent . CVP pressure curve : RA pressure in patient with severe tricuspid valve regurgitation (e.g. as a result of a right ventricular load): The v wave is higher than the a wave. The v wave is usually lower than the a wave. The x -descent is also reduced. The curve of the right atrium looks like the curve of the right ventricle (" ven-tricularized "). In the physical examination, the high v wave can be seen as a systolic prominent ("pulsating") jugular vein which is referred to as the Lancisi sign.

18. CVP pressure curve RA pressure in patient with impaired atrial-ventricular synchronization e.g. with AV dissociation in case of AV block III or with ventricular pacemaker sti-mulation . The right atrium contracts against the closed tri-cuspid valve which massively increases the pressure in the right atrium. It results in a very high a wave (fusion wave; giant / cannon-a wave). CVP pressure curve: RA pressure in patient with pericardial tamponade: It shows a reduction or even a loss of the y -descent, with maintained x -descent , d ue to the increased intrapericardial pressure the right ventricle can no longer be filled during diastole. Consequently, no more blood can flow from the right atrium into the right ventricle and there is no loss of pressure in the right atrium.

19. Interpretation CVP ↓: hypovolemia (lack of volume); further reasons: venodilatation (e.g. as a result of a reduction of the sympathetic tone [vegetative regulation], administration of vasodilators), reduction of pressure in the thorax (e.g. in case of forced inspiration, inspiratory stridor) CVP ↑: Hypervolemia cardiac insufficiency pulmonary embolism pericardial tamponade (fluid resuscitation required here [in addition to pericardial puncture]) venous constriction (e.g. as a result of a vasopressors like noradrenaline) pressure increase in the chest mechanical ventilation with (high) PEEP (PEEP increases the CVP. A rule of thumb is: In order to calculate the true CVP, half of the set PEEP has to be deducted from the measured CVP [given a normal compliance and resistance of the lung). auto-PEEP (syn.: intrinsic-PEEP; i.e. as a result of hyperinflation in patients with obstructive pulmonary disease) tension pneumothorax Trendelenburg positioning

20. Positioning CVC can be placed in: Internal jugular vein (to right vein at 15 cm, to left vein at 18 cm); preferably use the right internal jugular vein; CVC-positioning in the left internal jugular vein carries a high risk of brachiocephalic vein wall perforation. T horacic duct may be injured, especially with proximal puncture. subclavian vein (No.2; sew to right vein at 17 cm, to left vein at 22 cm) femoral vein (caution: increased rate of thrombosis and infection!) Others : cephalic vein, basilic vein, brachiocephalic vein (fixed on tissue → also open during hypovolemic shock), external jugular vein (fixed on tissue → also open during hypovolemic shock)

21. Peripherally Inserted C entralvenous Catheter (PICC) C entral venous catheter with the top in the superior caval vein which is introduced via peripheral puncture (mostly cubital or brachial) L ength 60 cm, 1-2 lumens, made of polyurethane or silicone A ll types of infusions (including parenteral nutrition and chemotherapy) special form: midline catheter (shorter version of the PICC: peripheral placement, the tip of the catheter is only in the axillary and subclavian vein, but not in the superior caval vein)

22. PICC (C.R. Bard, Inc.) C omponents of a CVC set

23. Procedure C heck coagulation (platelets > 50,000/ μl , Quick > 50% or INR < 1.5; but this is only optional: The insertion of a CVC is definitely also possible in the case of reduced coagulation if necessary (at best ultrasound guided) L owering of head (Trendelenburg positioning) to prevent air embolism Note: but caution in spontaneously breathing obese patients: The apical relocation of fat mass in the Trendelenburg positioning may cause a reduction of the lung volumes and quickly lead to acute respiratory insufficiency (OSDS [obesity supine death syndrome]). L owering of the head is contraindicated in patients with increased intracranial pressure (ICP).

24. Procedure Cont… sterile conditions (including hand disinfection, sterile gloves, sterile coat, cap, surgical mask) disinfection of the puncture site ECG monitoring, turning on of the systole beep tone tapering with sterile gauze local anesthesia e.g. with lidocaine ( Xylocain ) possibly also for mechanically ventilated patients When the local anesthesia has been conducted, the syringe containing lidocaine should be put to the other end of table to avoid confusing syring e containing saline with that containing lidocaine. F ill the syringe with 1-2 ml saline solution, aspirate and observe whether venous or arterial blood in the syringe.

25. Procedure Cont… Puncture of the vein, aspiration of blood insertion of the Seldinger wire small skin incision with scalpel pre-stretching with the dilator (to expand the channel) insertion of the catheter over guide wire ( Seldinger technique) start insertion of the catheter into patient after appearance of the wire (caution: loss of wire); insertion up to the corresponding mark internal jugular vein: right 15 cm, left 18 cm subclavian vein: right 17 cm, left 22 cm removal of Seldinger wire sew with a thread aspiration of blood and flushing of all lumens

26. Puncture of Internal J ugular V ein L ateral positioning of the head puncture site: based on landmark ("blind technique") lateral to the palpable carotid artery Normally, the internal jugular vein is located lateral to the common carotid artery. T his rule only applies if the head lies in a straight position. The head is often turned to the side during CVC insertion. In this position the vein is often directly anterior to the artery and therefore ventral instead of lateral to the artery. lead structure: medial edge of the sternocleidomastoid muscle

27. Puncture of Internal J ugular V ein… B ased on sonography: Insertions of CVC or Shaldon catheter into the internal jugular vein are best done under sonographic control (ultrasound guided). This minimizes the chances of error and multiple punctures are avoided (even in obese patients). application of a sterile cover over probe (transducer) and cable, use of sterile ultrasound gel or skin disinfectant 7.5 MHz transducer (linear array probe) compression ultrasonography (B-mode image): The vein can be compressed, but not the artery. i.a. exclusion of thrombus

28. Also, it is not uncommon to incidentally discover a thrombus in the internal jugular vein (especially in case of a previously inlying CVC) which would not be seen otherwise without ultrasonography and which would then be pushed further along by the guide wire or the dilator (risk of pulmonary embolism). In collapsing Vein (due to exsiccosis) and therefore cannot be seen well, the PEEP can be increased for a short time for the puncture in mechanically ventilated patients (e.g. to 10 cmH 2 O) Overstretching of the alveoli leads to compression of the neighboring capillaries, with the result that that the right ventricular afterload and thus the pressure in the right heart and consequently also in the internal jugular vein increases.

29. Anatomy of subclavian vein Schematic representation of the anatomy

30. Puncture of Subclavian V ein P uncture site: 3 cm below the clavicle exactly in midclavicular line (MCL) in the direction of the clavicula ultrasound guided (imaging of the vein in the longitudinal view is more difficult than in internal jugular vein) Advantages: The ligamentous apparatus keeps the vessel open (also during hypovolaemic shock). L owest risk of infection and thrombosis compared to internal jugular vein and femoral vein. N o hindrance of cerebral venous drainage: primarily in neurosurgical intensive care units (avoidance of raise intracranial pressure).

31. D isadvantages: H ighest risk pneumothorax (compared to internal jugular vein and femoral vein, therefore be careful with patients suffering from severe respiratory insufficiency. no possibilty of compression in the case of mistakenly arterial puncture ultrasound guided insertion more difficult (no compressibility) than with internal jugular vein.

32. Puncture of Femoral Vein Puncture site: 3 cm below the inguinal ligament location of the vein medial to the artery (mnemonic "IVAN": inner vein - artery - nerve) preferably also ultrasound guided in patients with coronary artery disease (CAD) if possible, on the left side (The right groin should be spared for establishment of an access for cardiac catheterization procedures!) D isadvantages: I ncreased rate of thrombosis and infection H indrance in mobilization of the patient

33. Position control intracardiac ECG recording (most common method; endo-ECG, e.g. Alpha-Card) chest X-ray The tip of the CVC should be at the height of the tracheal bifurcation (main carina). Only administer isotonic solutions through the CVC before checking its position (e.g. by X-ray examination)! contralateral CVC puncture of subclavian vein only after exclusion of a pneumothorax ipsilateral (otherwise risk of double-sided pneumothorax which may be lethal) The CVC should always be inserted on the side which looks worse in the chest X-ray: If a pneumothorax occurs, only the already sick lung will collapse and not the healthy lung. echocardiography (transthoracic) BGA (especially pO 2 ) gravity infusion (When the catheter is in the artery, no fluids can be infused by gravity alone). connection to the pressure bag

34. Intracardiac ECG recording • evaluation of P wave - -superior caval wein : normal P wave (correct position) - -right atrium: peaked P wave (incorrect [too deep] position) • only possible in sinus rhythm (not in atrial fibrillation)

35. Alpha-Card: intracardiac ECG recording for position control of the CVC Intracardiac ECG recording for position control of the CVC

36. Complications Ha ematoma : especially in compromised coagulation; caution: difficult intubation in case of a large hematoma in the neck Pneumothorax (most frequently in puncture of the subclavian vein), hemothorax, pleural effusion due to infusion of fluids (" infusothorax ") C hylothorax (leakage from the thoracic duct; particularly in puncture the left subclavian vein) A ir embolism (see page 674; especially when removing the CVC, which may only be performed in lying and never in sitting position [exception: CVC in the femoral vein]) N erve injuries: i njury of the vagus nerve (passes medial to the internal jugular vein) → phrenic paralysis (one-sided diaphragmatic eventration) injury of the cervicothoracic ganglion either by puncture or by local anesthesia (unintended block) → Horner's syndrome (triad: ptosis, miosis, enophthalmus )

37. Complications A rterial puncture → bleeding (Bleeding into the neck may cause a compression of the airway!), via falsa insertion (e.g. into the aortic arch instead of subclavian vein), dissection, arterio-venous fistula (continuous, i.e. systolic + diastolic murmur [machinery murmur = Gibson murmur]) cardiac arrhythmia (The Seldinger wire often causes premature ventricular contractions [ventricular extrasystoles] in the right atrium and right ventricle, maybe even ventricular tachycardia.) myocardial perforation, pericardial tamponade C atheter-related infections, sepsis T hrombosis (most common in femoral vein) Loss of the wire (guidewire embolism) or the CVC which then dislocates into the right heart or pulmonary artery (therapy: retrieval via right heart catheter using the GooseNeck snare,"right heart catheter retrieval of foreign bodies).

38. Infections Definition • colonization p.d. > 15 CFU (colony-forming units [semiquantitative methode according to Maki]) on the catheter tip • designations (synonyms): - - CRBSI (catheter related blood stream infection) - - CABSI (catheter associated blood stream infection) - - CVCBSI (central venous catheter blood stream infection) Epidemiology • frequency: - - 1 case per 1,000 catheter days (DEVICE-KISS) - - 8,400 cases of CVC-associated sepsis only in Germany every year

39. third most common nosocomial infection (after urinary tract infection and pneumonia) • CVCs via the subclavian vein have the lowest risk of infection (3-SITES study: Parienti et al, N Engl J 2015). • CVCs cause 90% of all blood stream infections. • increase after the first week (especially from the 10th day on); before that, it is unlikely that the CVC in the cause of fever) • mortality: 11.5%

40. Pathogens • coagulase-negative staphylococci ( CoNS ; No.1): primarily staphylococcus epidermidis (90% methicillin-resistant [MRSE: methicillin-resistant staphylococcus epidermidis]) • staphylococcus aureus (No.2; usually M R SA [methicillin-resistant staphylococcus aureus]) • gram-negative bacteria ( v.a. E. coli, Klebsiella, Pseudomonas) • candida (No.3) • enterococci

41. Symptoms • fever of unknown origin, occurring after longer CVC dwell time (After approximately a dwell time of the CVC of 10 days the CVC can be considered as a cause of fever, before that rather not!) • reddened puncture site, pus • sepsis

42. Diagnosis • smear of puncture site • separate blood cultures (central [CVC] and peripheral) • removal of CVC and microbiological examination - - Cut off the tip of the CVC (3-5 cm) and then put it into a sterile tube (without transport medium)! - - The CVC tip is then rolled over an agar plate with sterile tweezers. - - CVC tips should not be tested in the laboratory routinely) only in the case of suspected CVC infection).

43. D-TTP • differential time to positivity • simultaneous examination of peripheral and central (CVC) blood cultures • D-TTP = TTPCVC - TTPperipheral • D-TTP > 2h → → catheter infection (90% sensitivity, specificity 98%) Therapy • removal of CVC and if necessary, placement of a new catheter • only fever without further symptoms → no antibiosic treatment necessary ("watchful waiting") • antiinfectives

44. Antiinfectives • CoNS : - - means of choice: vancomycin (alternative: daptomycin) - - duration of therapy: 5-7 days - - If only one blood culture is positive with CoNS , an antibiotic treatment is not generally yet indicated (after removal of the CVC), provided there is no intravascular, intracardiac ( i.g. prosthetic valve) or orthopedic foreign material. In most cases it is only a contamination (especially if blood cultures are only positive after 48h). Antibiotic treatment is only indicated if futher blood cultures (CVC and peripheral respectively peipheral after removal of the CVC) are positive. • staphylococcus aureus (duration of therapy: 14 days) - - MSSA: flucloxacillin, cefazolin - - MRSA: vancomycin, daptomycin • candida: - - fluconazol or echinocandin - - duration of therapy: 14 days after the last negative blood culture • possibly antibiotic lock (in-situ therapy, e.g. infection of a port) - - gram-positive (e.g. CoNS ): vancomycin 2 mg/ml - - gram-negative: ciprofloxacin 2 mg/ml

45. Prophylaxis • aseptic insertion (MBP: maximum barrier precautions) - - the most important prophylactic measure - - cap, surgical mask, sterile gown, sterile gloves, large fenestrated drape, disinfection of the skin - - This includes the clear recommendation to disinfect hands before putting on sterile gloves which is unfortunately often neglected. - - If you use the ultrasound, not only the transducer (probe) must be within the sterile cover, but also the supply cable. - - In patients with a tracheostoma a CVC in the internal jugular vein should be avoided. • The less lumens a CVC has, the lower the risk of infection. • guidewire exchange of the CVC allowed up to a maximum of 48 h after placement (then new CVC insertion necessary!) • lowest risk of infection in case of CVC insertion via subclavian vein (but highest risk of pneumothorax) • daily inspection of the puncture site • daily check, whether a CVC is still necessary and if not removal

46. A routinely exchange of CVCs (e.g. placement of a new CVC every 10 days) does not have any advantage. A new catheter should only be inserted in case of clinically suspected infection. • If sealing plugs are removed from the CVC ( i.g. for the injection of a drug), it is not allowed to put the same plug on again. They have to be rejected and changed by a new one. • change of infusion systems: - - If blood products are applied, the systems should be changed no later than 6h. - - If lipid solutions are applied, the systems should be changed no later than 24h. - - Otherwise they should be changed no more often than after 96h.

47. possibly using CVCs with anti-infective coating: In a French multicenter study (Timsit et al, JAMA 2009) significantly less catheter-associated infections could be observed at the CVC puncture sites of approximately 1,600 patients due to the use of chlorhexidine-impregnated sponges ( Biopatch ). Meta-analyses (Hockenhull et al, Crit Care Med 2009; Safdar et al, Crit Care Med 2014; Maunoury et al, PLoS One 2015) also showed a reduction of the infection rate due to the use of CVCs with anti-infective coating. In Germany they are recommended from the Commission for Hospital Hygiene and Infection Prevention for patients at high risk (especially with severe immunosuppression).

48. Thrombosis Thrombosed CVCs should always be changed or removed because of the increased risk of infection If necessary, local lysis of thrombosed and urgently needed lumens (e.g. highly catecholamine-dependent patient; also a good option in port-a- cath system) with 2 mg Alteplase ( Actilyse ) in 2 ml normal saline (recanalization rate: 90% 0.2 ml urokinase 5,000 U/ml (recanalization rate: 75%. N o advantage of systemic anticoagulation with heparin

49. Intranasal Drug A pplication Definition: intranasal drug application is especially recommended if intravenous access is difficult or impossible: seizures (especially in children) pain (especially suitable for children, e.g. for pain treatment in case of burns / scalding [An out-of-hospital placement of an intravenous access is rarely necessary in these cases!) aggressiveness (e.g. intoxicated patient who flails around and can only be held down by several persons [recommendation: intranasal application of 15 mg midazolam]) heroin intoxication (intranasal application of the antidote naloxone) The drug is absorbed in the olfactory region by the mucous membrane.

50. apply drugs with a 2 ml syringe (max. 1 ml per nostril [otherwise it runs back down the throat and would be swallowed]), always spread on both nostrils (larger absorption surface and therefore faster absorption) only use highly concentrated drug solutions (no dilutions), e.g. midazolam 5 mg/ml (not 1 mg/ml), ketamine 50 mg/ml or S-ketamine 25 mg/ml especially suitable for low-molecular and lipophilic drugs phases of absorption: early phase: nasal absorption late phase: gastrointestinal absorption (because a certain amount is always swallowed) not effective in sniff or nosebleed (epistaxis) The intranasal application of a drug, however, constitutes an off-label use.

51. Applicators Mucosal Atomizatio (MAD): The applicator is inserted into the nose. Carpuject OptiNose Accuspray Nasal Automizer Dosage midazolam: 5 mg/ ml Fentanyl & sufentanil 0.05 mg/ ml, 2 μ g/kg morphine 10 mg/ ml (0.1 mg/ml). K etamine: 50 mg/ ml, (apply 1 ml); 1-5 mg/kg (0.02-0.10 ml/kg) S-ketamine ( Esketamin ) 25 mg/ ml. Naloxone 0.4 mg/ ml, (0.4-0.8 mg) F lumazenil: 1 ml = 0.1 mg G lucagon : 2 mg dissolved 1 ml of liquid (e.g. in the case of hypoglycemia if no venous access is possible).

52. ARTERIAL ACCESS Indications continuous invasive blood pressure measurement (IBP) frequent blood gas analyses (e.g. non-invasive ventilation in case of COPD exacerbation) access (sheath) to coronary angiography cannulation for va -ECMO

53. Principle The mechanical energy of the pulse wave (pressure wave) gets to a water column in the catheter which is connected to a liquid-filled hose system. The pulse wave is transmitted to a transducer, where the pulse wave of the water column is transduced into an electric signal. There is a waterproof membrane (silicone) in the transducer which gets deformed by the pressure wave. There are strain gauges in the membrane, which electrical resistance is altered due to the deformation. The change of the resistance is mathematically transformed and linearized and finally demonstrated as a continuous pressure curve on the monitor.

54. Principle cont … The monitor amplifies the output signal from the transducer, filters the noise and displays the arterial waveform on a screen. The arterial catheter (line) is connected to a measuring system, a pressure transducer, a transmission module and then with a monitor. First, a zero calibration is required: The three-way stopcock between the arterial catheter and the pressure transducer must be open to the atmosphere so that a pressure equalization with the environment (atmospheric air pressure) can take place. This is taken as the reference point for setting the transducer to zero. To prevent thrombosis the measuring system is connected to a continuous catheter flushing apparatus (3 ml/h with 500 ml of sodium chloride 0.9% and 500 IU of UFH). But this is no longer usual in our ICU.

55. P ressure transducer; P ressure bag with saline; C atheter [arterial line] in radial artery; Pressure transducer C onnections for a Swan-Ganz catheter; C ressure cable; M onitor; Triple- devided line Principle of invasive blood pressure measurement

56. Indications management of catecholamine treatment management of antihypertensive treatment (e.g. sodium nitroprusside) peri-operative in patients with ASA > 3 (ASA: American Society of Anesthesiology)

57. Possible Errors incorrect placement of the pressure transducer missing zero calibration abnormal damping of the system Underdamping: Natural oscillations may occur spontaneously in liquid-filled systems. If their frequency is in the range of the resonant frequency of the measuring system, the oscillations may be superimposed. too high amplitude (too high blood pressures are measured), sharp peaks O verdamping ("moderate peak"): air bubbles, blood clots, contrast medium, thrombosis, suction of the catheter to the vessel wall, kinked catheter, too low flushing pressure in the flushing solution, too long pressure line (distance to pressure transducer too long > 1 meter) amplitude too low (too low blood pressures measured), rounded peaks

58. Flush Test A nalysis flush-test is conducted in order to check, whether there is a normal or abnormal damping of the system. Snap flush to generate square wave. After flushing, the arterial curve is studied ( known as decay phase) Normal damping usually causes only one oscillation before returning to baseline (one negative and one positive amplitude). U nderdamping: two or more oscillations before returning to baseline O verdamping: no oscillations (response speed is too slow)

59. Different blood pressure measurement results depending on the position of the transducer: If the pressure transducer is located above heart level, too low blood pressure values will be measured. If the pressure transducer is located below heart level, too high blood pressure values will be measured. A: normal damping; B: underdamping (too high amplitude, sharp peaks); C: overdamping (too low amplitude, rounded peaks)

60. flush-test Done to check if the system is damped correctly, the flush-test is carried out and the decay phase (after the flush stop; oscillations return to baseline) is observed. (A) There is only one oscillation during decay phase in normal damping (B) there are several oscillations during decay phase in underdamping and (C) you find no oscillation during decay phase in ov erdamping.

61. Placement R adial artery (standard) Femoral artery (at the level of the inguinal ligament) ulnar artery brachial artery axillary artery

62. Femoral Artery (at the level of the inguinal ligament) A dvantage: can often also be punctured in case of shock (in contrast to radial artery) D isadvantages: increased rate of thrombosis and infection reduced mobility of patient The right femoral artery is often used as an access (sheath) for coronary angiography and should therefore be spared in patients which may soon have to undergo cardiac catheter examination. But the standard access nowadays for coronary angiography is the radial and no more the femoral artery .

63. Radial Artery D orsoflexion of the wrist and immobilization D isinfect the puncture site, cover with fenestrated drape L ocal anesthesia with lidocain (Xylocaine; possibly also in mechanically ventilated patients) P uncture 30-45° with the needle tip points upwards, not downwards • in case of difficulties (e.g. hardly detectable pulse) sultrasound guided • when blood flows out of the needle: advance wire (without resistance), remove the needle, pass the plastic cannula over the wire, remove the wire, sew with a thread - if necessary (In our ICU, the radial artery catheter is only glued, the femoral artery catheter is sewn.) • connection to flushing system and pressure sensor

64. Allen Test and Barbeau Test Allen’s test is done to evaluate the patency of the ulnar artery before puncture of the radial artery. Procedure: The examiner places digital occlusive pressure over the radial and ulnar arteries at the wrist for one minute. The patient repeatedly makes a fist. The hand becomes pale. The digital pressure over the artery is released, the test is negative if hand turns pink within 5-7s, puncture of the radial artery can be done. N o longer strongly recommended except for legal and forensic purposes Barbeau test is done to test for collateral blood supply to the hand Here a saturation clip is applied to the thumb and then the radial artery is compressed for two minutes. If there is sufficient collateralization, neither the curve ( pletysmography ) nor the saturation value (oximetry) should change.

65. Techniques • direct (artery cannula) • indirect ( Seldinger technique)

66. Curve The arterial pressure curve typically shows the following characteristics: high dicrotic notch large area under the curve no cardiac cycling (amplitude fluctuation of the arterial pressure curve) Form of arterial pressure curve: The maximum marks the systolic, the minimum the diastolic blood pressure. The mean arterial blood pressure (MAP) corresponds to the area under the arterial pressure wave and is calcu-lated according to the equation MAP = (SBP + 2x DBP) / 3. The systole ranges from the anacrotic notch (opening of the aortic valve) to the dicrotic notch (closing of the aortic valve), the diastole ranges from the dicrotic to the anac-rotic notch (Greek: " dikrotos " double-beating; " anakrot ": upstroke, upbeat). The increase after the dicrotic notch is due to the Windkessel effect.

67. H ypovolemia (volume depletion) -the arterial pressure curve shows the following characteristics: low dicrotic notch small area under the curve cardiac cycling (syn: systolic pressure variation [SPV]; = amplitude fluctuation of the arterial pressure curve) [possible only when sinus rhythm]) Arterial pressure curve in case of hypovolemia: You can see the classic "cardiac cycling" syn.: systolic pressure variation ( SVR)

68. Complications B leeding, hematoma - The artery catheter system must always be connected to the monitor and must never (e.g. for transport) be plugged. vasospasm (especially in radial artery), ischemia thrombosis with ischemia, embolism infection nerve lesion mistakenly administered intra-arterial injections with necrosis (note: only use red and never blue three-way stopcocks and plugs) compartment syndrome (puncture of radial artery)

69. Complications R etroperitoneal hematoma (puncture of femoral artery). definition: bleeding into the retroperitoneal space (especially in the case of a too high puncture of the femoral artery) symptoms: back pain, groin pain, ipsilateral leg weakness, paleness (drop in hemoglobin), hypovolemic shock therapy: conservative (mostly sufficient; i.a. administration of RCC, FFP) interventional (radiological; especially in hemodynamically unstable patients): balloon occlusion, embolisation with coils, implantation of a covered stent surgical (rarely necessary)

70. A neurysm spurium (especially in the case of a too low puncture of the femoral artery) H ematoma (aneurysm sac) with a connecting channel (aneurysm neck) to the femoral artery a pseudoaneurysm symptoms: groin pain, pulsatile swelling D iagnostic: auscultation: systolic murmur duplex-sonography T herapy: manual compression of the channel with the linear transducer (for at least 30 minutes; mostly sufficient; then application of a compression dressing for 12 hours) injection of thrombin (ultrasound guided) in the aneurysm sac surgical (ligation of the connecting channel)

71. dissection arterio-venous fistula (AV fistula) auscultation: continuous, i.e. systolic and diastolic murmur (machinery murmur [Gibson murmur]) therapy: spontaneous closure (in most cases) endovascular implantation of a covered stent (only rarely necessary [e.g. in volume load due to the left-right-shunt in pre-existing congestive heart failure])