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Chapter 6 Patient Monitors

Chapter 6 Patient Monitors. 마취통증의학과 1 년차 성 준 경. Outline. Cardiac monitors Arterial BP Non invasive Invasive EKG Central venous catheterization Pulmonary artery catheterization Cardiac output Pulmonary monitors Precordial & esophageal stethoscopes Pulse oximetry Capnography

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Chapter 6 Patient Monitors

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  1. Chapter 6Patient Monitors 마취통증의학과 1년차 성 준 경

  2. Outline • Cardiac monitors • Arterial BP • Non invasive • Invasive • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Pulmonary monitors • Precordial & esophageal stethoscopes • Pulse oximetry • Capnography • Anesthetic gas analysis • Neurologic system monitors • Electroencephalography • Evoked potentials • Miscellaneous monitors • Temperature • Urinary output • Peripheral nerve stimulation

  3. Cardiac Monitors :Arterial BPNIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Introduction • Mean arterial BP (MAP) • Time weighted avg. of arterial pr during a cycle • (SBP+2DBP)/3 • Factors that induces in BP differences • Proximity • Gravity • Lt & Rt

  4. Cardiac Monitors :Arterial BPNIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Ix & CIx • Absolute Ix in use of any anesthetics • Freq: 환자 상태와 수술 종류에 따라 다르지만 대개는 3-5min 마다 측정 • Vascular abnormalities(eg, dialysis shunt), IV line 있을 시 피하는게 좋다. • Techniques • Palpation • Doppler probe • Auscultation • Oscillometry • Arterial tonometry

  5. Cardiac Monitors :Arterial BPNIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • A. Palpation • Underestimation • Unable to check DBP and MAP • B. Doppler Probe • 위의 Palpation 과 같은 개념이나 촉지 대신 doppler probe 이용 • Obese pt, 소아 환자, in shock pt, 에 유용 • 역시 SBP만 check 가능 • C. Auscultation • Korotkoff sound • Cuff pr를 수축기와 이완기 pr 사이로 맞추면 turbulent flow 가 생기며 특징적인 korotkoff sound가 cuff 아래 위치시킨 청진기를 통해 들린다. • SBP, DBP, MAP check 가능

  6. Cardiac Monitors :Arterial BPNIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • D. Oscillometry • Pulse  Oscillation 유발 • Microprocessor가 특정 algorithm을 통해 SBP, MAP, DBP 를 계산해 냄. • SBP lv로 cuff pr 가 맞춰졌을때 oscillation 증가 • MAP시 oscillation highest • Limitations • 부정맥이 있을시 unreliable할 수 있다. • Cardiopulmonmary bypass시 사용하면 안됨 • 전세계적으로 추천되는 NIBP method • E. Arterial tonometry • Pr transducer 를 동맥이 지나는 피부위에 위치시킴. A-line과 유사한 waveform을 나타내며 지속적인 감시가 가능하다. 하지만 movement artifact에 민감해 잦은 calibration을 요하는 단점이 있다.

  7. Cardiac Monitors :Arterial BPNIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Clinical consideration • BP  organ blood flow • But, Flow = Pr/resistance • pr높아도 저항도 같이 높아지는 경우 flow 는 늘어나지 않게 된다. • 단순히 indicator 로만 봐야 하지 절대적이지는 않다. • Proper cuff size • Automated BP monitor 사용시 주의사항 • 너무 잦은 측정, 부정확한 사용 방법 • Nerve palsy, 정맥으로 주입한 제제의 extensive extrarvasation 유발 가능.

  8. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Ix & CIx • Ix: • induced hypotension • wide BP swing 예상 • end-organ dz로 정확한 BP조절이 필요한 경우 • 잦은 ABGA가 필요한 경우 • CIx • collateral이 없는 곳 • preexisting vascular insufficiency 예상되는 경우 (ex. Raynaud’s phenomenon)

  9. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Techniques & Cx : Selection of an artery • Radial artery • Superficial • Collateral 존재 • 5%에서 insufficient collateral flow • Allen test • Palpation • Doppler probe • Plethysmography • Pulse oximetry • Ulnar artey • Deeper & more tortuous • 보통은 선택하지 않는다.

  10. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Brachial artery • Antecubital fossa 에 위치 • Proximity  less distorted waveform • Elbow에 위치  kingking 가능 • Femoral artery • Pseudoaneurysm • Atheroma • Infection • Arterial thrombosis • Aseptic necrosis of the femur head in children • Excellent access

  11. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Dorsalis pedis and posterior tibial arteries • Most distorted waveform • Modified Allen’s test • Axillary artery • Hematoma, traumatic cannulation  nerve damage • Air, thrombi

  12. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Technique of radial a. cannulation • Supination & extension • A-line setting • Palpation of artery • 0.5ml Lidocaine inject directly above the artery with 25,27 gauge needle • 45도로 촉지부위를 향해 advance • Blood flashback이 확인되면 needle 각을 30도 낮추고 1-2mm더 advance. Needle 뿐만 아니라 카테터 팁이 확실히 들어가게 하기 위해. • Catheter 삽입 • 카테터를 “Spinning” 해주는 것이 도움이 되기도. • 3번째, 4번째 손가락으로 동맥위에 압력을 가함 • Transducer tubing의 확실한 고정 • Fixation

  13. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Complications • Examples • Hematoma • Bleeding • Unstable fixation • Vasospasm • Arterial thrombosis • Embolization of air bubble or thrombi • Necrosis of skin overlying the catheter • Nerve damage • Infection • Loss of digits • Unintentional drug injection • 증가요인 • Prolonged cannulation • Hyperlipidemia • Repeated insertion attempts • Female gender • Extraecorporal circulation • Use of vasopressors

  14. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Clinical consideration • Arterial waveform의 정확한 측정을 위해서는 catheter-tubing-transducer sys.이 arterial waveform의 highest frequency에 적절하게 반응하여야 함. • Decrease the frequency of the system (Damping) : addition of tube, stopcocks, air • Overdamping시 : underestimating systolic pr. • Underdamping시 : falsely high SBP • Damping coefficient : 0.6 ~ 0.7 이 적절. High pr. Flush test로 구함.

  15. Cardiac Monitors :Arterial BPIBP monitoring • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • 정확한 측정값을 위해서는 • Tube length 최소화, 불필요한 stopcocks제거, air bubble제거, Low compliance tubing 사용 • 정확한 위치에서의 zeroing • Arterial waveform을 통해 얻을 수 있는 정보 • Upstroke  contractility • Downstroke  pph vascular resistance • 호흡주기동안 size의 과장 및 variation  hypovolemia

  16. Cardiac MonitorsEKG • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Ix & CIx • All patients • No contraindications • Techniques & Cx • Lead II • Parallel to axis atria  largest P wave • Arrythmia • Inf wall ischemia • Lead V5 • Rearranged three limb lead (Modified V5) • Ant & lat wall ischemia

  17. Cardiac MonitorsEKG • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Clinical considerations • Electrical potential generated by myocardial cells • Usage • Heart rate • Arrhythmias • Myocardial ischemia • Conduction abnormalities • Pacemaker malfunction • Electrolyte disturbance • Limitation • Artifacts • Patient or lead-wire movement • Use of electrocautery • Faulty electrodes • Monitoring filters • Lessen artifacts • ST seg distortion  impede the diagnosis of ischemia

  18. Cardiac MonitorsEKG • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Preinduction rhythm strip • Intraoperative EKG change 와의 비교 • ST segment changes • ECG must be standardized so that a 1mV signal results in a deflection of 10mm on a standard strip monitor • WPW synd, BBB, extrinsic pacemaker capture, digoxin therapy  ST seg 관련 정보의 이용이 불가능 할 수 있다. • Myocardial ischemia • Criteria • Flat or downsloping of ST seg. Depression exceeding 1 mm, 60 or 80 ms after the J point(QRS complex 의 마지막), particularly in conjunction with T wave inversion. • ST seg. Elevation with peaked T wave • Audible beep • Make sure its loud enough!  detect rate & rhythm changes

  19. Cardiac MonitorsCentral Venous Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Ix • CVP monitoring • Fluid administration • Drugs infusion, TPN • Air emboli aspiration • Gain venous access • Insertion of pacing leads • CIx • Renal cell tumor extension into the RA • Fungating TV vegetations • Relate to cannulation site & patient condition • Ex) anticoagulation tx pt – int jugular vein cannulation

  20. Cardiac MonitorsCentral Venous Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Techniques & Cx • SVC와 RA와의 junction 바로 위 • Intrathoracic pr.에 exposed • CVP change according to ventilation method • Spontaneous : 흡기시 CVP 증가 호기시 감소 • Controlled : 흡기시 CVP 감소 호기시 증가 • Should be measured during end expiration • Various sites • Subclavian • Cx • Pneumothorax • Infection • Right int jugular vein • Left int jugular vein • Cx • Vascular erosion • Pleural effusion • Chylothorax

  21. Cardiac MonitorsCentral Venous Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Procedure • Trendelenburg position • Full aseptic technique • Triangle • Local anesthetic • Locator needle aspiration • 18G thin-wall needle • J-wire • Needle removal & Pliable silastic catheter • Guidewire removal • Catheter tubing connection & Secure • CXR confirmation • Caution • Cannulation into a artery • Transducing vessel’s pr waveform • Comparing color or PaO2 • Heart chamber 내로의 migration • Should be changed every 72 hrs • Risk of central venous cannulation • infection, air or thrombus embolism, arrhythmia, hematoma, pneumothorax, hemothorax, hydrothorax, chylothorax, cardiac perforation, cardiac tamponade, nerve trauma

  22. Cardiac MonitorsCentral Venous Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Clinical considerations • CVP는 RVEDV의 주요 결정인자인 Rt. Atrial pr.와 거의 동일 • Healthy heart에서 Rt and Lt ventricular performance가 같다고 할 수 있으므로 CVP로 Lt. ventricular filling을 평가할 수 있다. • a wave : atrial contraction • c wave : ventricular contraction시 TV의 elevation • v wave : TV가 닫혀있을 때 venous return • x descent : systole시의 TV의 downward displacement • y descent : diastole시 TV opening

  23. Cardiac MonitorsPulmonary Artery Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Ix • ASA에서는 PAC의 사용 적절성은 operation, setting 그리고 환자와 관련된 risk를 종합적으로 고려해서 결정된다고 하였다. • CI, preload, volume status, mixed venous vol의 산소화 정도를 알고야 할 때 • Hemodynamical instability • Hemodynamic Cx이 발생할 가능성이 높은 수술

  24. Cardiac MonitorsPulmonary Artery Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • CIx • Relative CIx • Complete BBB  complete heart block 가능 • WPW synd, Ebstein malformation  tachyarrhythmia 발생 가능 • Pt prone to hypercoagulation  thrombus formation • Bacteremic pt  nidus of infection

  25. Cardiac MonitorsPulmonary Artery Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Techniques • Swan-Ganz catheter: • 110cm long • 7.5FR catheter • Polyvinylchloride body • Five lumen • Thermistor • Air channel • Proximal port • Ventricular port • Distal port

  26. Cardiac MonitorsPulmonary Artery Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • 15cm : RA • Central venous tracing 확인  ballooning • EKG monitoring • Sudden increase systolic pr. : RV • Sudden increase diastolic pr.(35~45 cm) :pulmonary a. • Minimal advancement : PAOP • Pulmonary a. rupture • Pr waveform monitoring  wedge reading (= catheter migration) • Difficult case • Deep inspiration • Head up position • Rt lat tilting position • Ice saline injection  stiffen catheter • Inotropic agent  CO증가

  27. Cardiac MonitorsPulmonary Artery Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Cx • Hemoptysis • May herald pulm a. rupture • Double lumen tracheal tube insertion • Increases according to duration • Should not exceed 72 hr

  28. Cardiac MonitorsPulmonary Artery Catheterization • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Clinical considerations • CVP나 P/E에 비해 보다 정확한 Lt. ventricular preload를 얻을 수 있음 • Mixed venous blood의 sampling이 가능 • Air embolism이나 myocardial ischemia의 detection이 가능 • Cardiac output측정 가능하여 여러가지 hemodynamic value 유추 가능 • PAOP는 LV 의 기능을 간접적으로 볼 수 있는 indicator이다

  29. Cardiac MonitorsCardiac Output • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Ix & CIx • PAC를 통해 얻은 정보를 가장 효과적으로 사용하기 위해서는 CO을 꼭 알아야 함. • No contraindications • Techniques & Cx • Thermodilution • Method • Fluid injection into RA • Change in blood temperature (inversely proportionate to CO) • Thermodilution curve • Computer processing • Rapid & smooth injection • Exact temperature and volume of the injectant • Precise calibration • Avoidance of electrocautry use

  30. Cardiac MonitorsCardiac Output • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Ultrasonography • TEE • LV filling • Ejection fraction • Contractility • Abnormal wall motion • Detection of myocardial infarction • Limitations • After anesthesia • Increased afterload vs ischemia • Variability of interpretation • Aortic compression in small children • Pulse doppler • Velocity of blood flow • TEE (aortic cross sectional area)와 병행  SV, CO 산출 • Continuous-wave suprasternal doppler • Velocity of blood flow • Uses nomogram (age, sex, weight)  estimates aortic cross sectional area • Transtracheal doppler • Doppler transducer  aorta diameter, velocity  CO

  31. Cardiac MonitorsCardiac Output • Cardiac monitors • Arterial BP • EKG • Central venous catheterization • Pulmonary artery catheterization • Cardiac output • Fick principle • Oxygen consumption = 동맥과 정맥의 oxygen content 차이 X CO • CO = Oxygen consumption = VO2 a-v O2 content difference CaO2-CvO2 • Oxygen consumption • Differenece between the oxygen content in inspired and expired gas • a-v O2 content difference • PAC와 A-line이 있으면 쉽게 구할 수 있다. • Clinical consideration • CO  indices reflecting function of circulatory system • Difficulty in interpreting pulmonary artery pressure • Effective pharmacological manipulation

  32. Pulmonary MonitorsPrecordial & Esophageal Stethoscopes • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Ix & CIx • Replaced by capnography & pulse oximeter • Esophageal varix, stricture • Techniques & Cx • Precordial • Esophageal • Better breath & heart sound • Intubated patient • Temperature probe, ECG lead, ultrasound probe, atrial pacemaker electrode

  33. Pulmonary MonitorsPulse Oximetry • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Ix & CIx • Mandatory monitor • Particularly useful in • Preexisting lung disease • Specific surgery (hiatal hernia repair…) • Special anesthesia (One lung ventilation…) • ROP 가능 neonate • No contraindications • Techniques & Cx • Sensor • Light source • Light detection • Hb의 red light 와 infrared light 흡수율 차이를 가지고 SpO2 산출 • Oxyhemoglobin  absorbs more infrared light (960nm) • Deoxyhemoglobin  absorbs more red light (660nm) • Arterial pulsation은 plethysmography를 통해서 확인이 가능하고 이는 non-pulsating venous blood나 조직으로부터의 light absorption을 보정해 준다.

  34. Pulmonary MonitorsPulse Oximetry • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Clinical consideration • Limited to detection of gross abnormality • Oxygen-Hb dissociation curve에 따라 실제 PaO2가 65mmHg 정도 밖에 않되는 경우에도 산소포화도는 90이 나올 수 있음. • 특별한 폐질환 있거나 FiO2가 낮지 않는 한 bronchial intubation의 detection이 어려울 수 있다. • 대개 oximeter는 low SpO2에서 부정확하며 SaO2와 SpO2 간에는 delay가 존재한다 • Purpose • Detecting esophageal intubation • Monitoring oxygen delivery to vital organs • Detecting postoperative pulmonary problems in recovery room • Severe hypoventilation • Bronchospasm • Atelectasis

  35. Pulmonary MonitorsPulse Oximetry • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Artifacts • CO poisoning  SpO2가 과대 측정 가능 • HbO2와 같이 COHb 역시 660nm의 빛 흡수율이 동일 • Methemoglobinemia  SpO2가 85%근처로 측정됨 (lidocaine, nitrates, sulfa제, metoclopramide 등을 사용하는 환자에서 흔히 증가) • Red light와 infrared light의 흡수율 차이가 거의 없다 • 실제 SaO2 high  실제보다 낮게 측정 • 실제 SaO2 low  실제보다 높게 측정 • 과도한 외부 조명, 형광등 • 형광등의 깜빡임 진동수가 oximeter의 발광 diode의 진동수와 일치 시 SpO2 과대 평가 • 움직임, malposition sensor (M/C) • Methylene blue dye, bluish nail polish • 660nm에서 red light와 근접 흡광도 가지는 푸른색  SpO2 과소평가 • Low perfusion • Hypothermia, severe anemia, low CO, high systemic vascular resistance  국소혈류 감소로 측정 어려움  nitroglycerin연고 사용 가능하나 저혈압 악화 가능

  36. Pulmonary MonitorsPulse Oximetry • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Pulse oximetry technique의 응용 • Mixed venous blood oxygen saturation (SvO2) • Noninvasive brain oximetry (rSO2) • Regional O2 saturation of Hb in brain • All regional microvasculature의 Hb • 정상치 : 약 70% • Cardiac arrest, cerebral embolization, deep hypothermia, severe hypoxia  rSO2 감소

  37. Pulmonary MonitorsCapnography • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Ix & CIx • 모든 마취에 유용. 특히 GA • 급격한 감소는 sitting craniotomy의 major Cx인 air embolism의 민감한 지표임 • No contraindications • Techniques & Cx • Infrared light absorption technique을 이용 (이산화탄소의 농도는 4.3um파장의 적외선의 흡수 정도에 비례) • Nondiverting (flowthrough) • Breathing circuit에 adaptor거치  여기를 통과하는 gas를 분석해 모니터에 표시 • Diverting (aspiration) • Breathing circuit 에서 sample line을 통해 monitor내의 sample cell내로 지속적으로 흡인 분석 • High aspiration rate(250ml/min) & low-dead-space sampling tubing  increases sensitivity and lowers lag time • Low tidal volume with high aspiration rate (eg. 소아 환자)  circuit 에서 fresh gas 유입  ETCO2희석 • 단점  Aspiration tube와 sampling cell내의 water precipitation  obstruction • 흡기시 CO2 gas의 detection • Expiration valve malfunction • exhausted CO2 absorbent

  38. Pulmonary MonitorsCapnography • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Clinical consideration • Esophageal intubation detection에 유용하나 bronchial intubation시에는 ETCO2만으로는 발견이 힘들다. • Sudden cessation  circuit disconnection • Rise in ETCO2  malignant hyperthermia 등에서 대사 증가시 • PaO2와 ETCO2와의 차이 • 약 2-5mmHg (Alveolar dead space 의미) • Decreased Lung perfusion (ex. Air embolism, CO감소, BP 감소) • Alveolar dead space 증가 • Expired CO2의 희석 • ETCO2 감소

  39. Pulmonary MonitorsCapnography • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Various conditions • Severe COPD • No plateau is reached before the next inspiration • The gradient between ETCO2 and PaCO2 is increased • Normal capnograph • Phase I: dead space • Phase II: mixture of dead space & alveolar gas • Phase III: alveolar gas plateau

  40. Pulmonary MonitorsCapnography • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Spontaneous respiratory effort • Incompetent expiratory valve or exhausted CO2 absorbent • Incompetent inspiratory valve

  41. Pulmonary MonitorsAnesthetic Gas Analysis • Pulmonary monitors • Precordial & Esophageal Stethoscopes • Pulse Oximetry • Capnography • Anesthetic Gas Analysis • Ix • 모든 흡입마취제를 이용하는 마취에 유용 • No contraindications • Techniques • mass spectrometry • Raman spectroscopy • Infrared spectrophotometry • piezoelectric crystal (quartz) oscillation • Oxygen analysis : do not absorb infrared light (nonpolar gases) • Galvanic cell • Paramagnetic analysis • Polarographic electrode • Airway pressure • low peak inspiratory pr.  ventilator or circuit disconnection • high peak inspiratory pr.  airway obstruction

  42. Neurological System MonitorsElectroencephalography • Neurological System Monitors • Electroencephalography • Evoked Potentials • Ix & CIx • Cerebral cortex cell에 의해 생성된 electrical potential의 recording • Cerebrovascular surgery중 cerebral oxygenation monitoring을 위해 종종 사용됨. • Monitoring of depth of anesthesia만을 위해서는 사용 안 함 • No contraindications • Techniques & Cx • International 10-20 system (Montage) : 각 electrode사이의 electrical potency 차이를 여과, 증폭하여 표시함.

  43. Neurological System MonitorsElectroencephalography • Neurological System Monitors • Electroencephalography • Evoked Potentials • Clinical considerations • EEG change during ischemia  high frequency activity • Mimicked by hypothermia, anesthetic agents, electrolyte disturbance, marked hypocapnia • Detection of this change  immediate review of possible causes of cerebral ischemia before irreversible brain damage occurs • BIS: correlates wit depth of anesthesia • Sedation : 65-85 • GA : 40-65 • Reduce patients awareness during anesthesia • Reduce resource utilization • Facilitate fast wake up time  shorter stay in recovery room

  44. Neurological System MonitorsEvoked Potentials • Neurological System Monitors • Electroencephalography • Evoked Potentials • Ix & CIx • Surgical procedures associated with possible neurological injury • Limited by availability of monitoring sites, equipment, and trained personnel • Techniques & Cx • Sensory/motor stimulation electrophysiological response • Brain stem auditor evoked responses (BAERs) • Somatosensory-evoked potentials (SEPs) • Motor-evoked potentials (MEPs) • 파형은 감각기관계의 해부 생리학적 구조 또는 상태에 의해 형성 • 유발전위 파형이 제대로 유발 형성되는지 여부 • 유발된다 하더라도 자극 후 유발 특정파형이 나타나는데 걸리는 시간이 지연되었는지 여부 각각의 감각기관계의 신경 생리학적 이상 유무를 평가

  45. Neurological System MonitorsEvoked Potentials • Neurological System Monitors • Electroencephalography • Evoked Potentials • Clinical considerations • Altered by many variables (anesthetics) • Balanced anesthetic techniques • Avoidance or constant low dose usage of volatile agents • Persistent obliteration of EPs  Predictive of postoperative neurologic deficit

  46. Miscellaneous MonitorsTemperature Miscellaneous Monitors Temperature Urinary Output Peripheral Nerve Stimulation • Ix & CIx • Advised in every patients undergoing general anesthesia over 15 min. • No contraindications • Techniques & Cx • Thermistor: semiconductor • Thermocouple: circuit of two dissimilar metals joined • Cx: trauma caused by the probes (ex. Tympanic membrane, rectal) • Clinical considerations • Hypothermia • Body temperature <36 • Metabolic oxygen requirements  protective during times of cerebral or cardiac ischemia • Deleterious physiological effects of unintentional hypothermia (Increases with 고령, 복부수술, 긴 수술, 낮은 수술 방 온도) • Post-op shivering • 5배까지 oxygen consumption  SaO2 , 심근허혈, 협심증 증가와 관련 • Tx: Meperidine 25mg • Maintain normothermia during op.

  47. Miscellaneous MonitorsTemperature Miscellaneous Monitors Temperature Urinary Output Peripheral Nerve Stimulation • Core temperature • Phase I: 전신 마취 후 첫 1시간. 1~2도 하강 • Phase II: more gradual decrease during 3~4th hour • Phase III: point of steady state or equilibrium (heat loss = metabolic heat production) • Hypothermia 기전 • Initial decrease in temperature  Redistribution of heat from warm central compartment to cooler peripheral tissues (anesthetic–induced vasodilators) • 전신마취시,  interfere hypothalmic function  inhibit central thermoregulation • 국소마취시 ( Spinal & epidural )  vasodilation (phase I 촉진), altered perception of blocked dermatome (phase II 촉진)

  48. Miscellaneous MonitorsTemperature Miscellaneous Monitors Temperature Urinary Output Peripheral Nerve Stimulation • Solutions for hypothermia • Pre-warming (convective forced-air warming blanket)  중심-말초간 체온 차이를 없앰으로써 phase I hypothermia를 예방 • Forced-air warming blanket, warm water blanket, heated humidification of inspired gas, warming of IV fluid, raising ambient OR temperature  phase II hypothermia 예방 • Heated cotton blankets (space blankets)  전신을 덮지 않는 이상 little effect • Monitoring sites (advantages & disadvantages) • Tympanic membrane • Reflects brain temperatture • Trauma • Rectal temperature • Slow response • Nasopharyngeal probes • Epistaxis • Thermister on PAC • Axillary temperature: skin perfusion • Liquid crystal adhesive strips placed on skin: inadequate • Esophageal temperature sensor • Best combination of economy, performance, and safety • Should be positioned behind the heart in the lower 1/3 of esophagus

  49. Miscellaneous MonitorsUrinary Output Miscellaneous Monitors Temperature Urinary Output Peripheral Nerve Stimulation • Ix & CIx • Congestive heart failure / renal failure / advanced hepatic disease / shock Cardiac surgery / aortic or renal vascular surgery / craniotomy / major abdominal surgery / large fluid shift가 예상되는 수술 / 긴 수술 • 감염의 위험이 높은 환자에게선 주의 • Techniques & Cx • Urine reflux와 infection risk의 최소화를 위해서 chamber는 항상 방광보다 낮은 곳에 위치시켜야 함 • Cx: Urethral trauma, infection, rapid decompression of a distended bladder  Hypotension유발 가능 • Clinical considerations • Foley catheter • Thermister 부착 가능 (urinary output 이 높게 유지되는 한 core temp 정확하게 반영) • Urometer: electronically monitor and record U/O & temp. • Urine output • Reflection of kidney perfusion & function • Renal , cardiovascular, and fluid volume status • Oliguria • Output less than 0.5mL/kg/hr (arbitrary) • Function of the patient’s concentrating ability and osmotic load

  50. Miscellaneous MonitorsPeripheral Nerve Stimulation Miscellaneous Monitors Temperature Urinary Output Peripheral Nerve Stimulation • Ix & CIx • Variation in patient sensitivity to neuromuscular blocking agents • Assessing paralysis in rapid sequence induction or continuous infusion of short acting neuromuscular blocking agents • Regional anesthesia  locate nerve to be blocked • No contraindications • Techniques & Cx • EKG silver chloride pad / subcutaneous needle  evoked mechanical or electrical response • Electromyography < Visual or tactile observation • Ulnar nerve stimulation  adductor pollicis m. • Facial nerve stimulation  orbicularis oculi • Direct muscle simulation should be avoided • Cx is limited to skin irritation and abrasion at the site of electrode attachment

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