Anaesthesia Machine, Monitoring L.Dadák ARK FNUSA & LF MU Anaesthesia Machine is able to ventilate the patient by defined mixture of gasses O2 Gas – ISO norm O2 - white lfractionally distill liquefied air into its various components, (N2 distilling as a vapor, oxygen O2 is left as a liquid. Stored as compressed gas. N20 - blue lpressure 5 MPa Air white/gray CO2 - gray gas liguid + gas N2O Anesthesia Machine is able to ventilate the patient by defined mixture of gasses Parts: 1.High pressure system 2.Low pressure system 3.Breathing circuit – in/expiratory part 4.Ventilation systems (manual and mechanical) 5.Scavenging system Parts of anesth. machine 1 2 3 4 5 High pressure system Compressed gas lCylinder Supply lPipeline Supply lOxygen Supply Pressure Failure Safety pO2 > pN2O lPressures regulator lmanometr Low pressure system lflowmeter O2, AIR, N2O lOxygen flush valve = Bypass, lVaporizer lAPL valve to deliver appropriate concentration, flow Flow of Anest. gasses lold machines 2..4 l/min llow flow > 1 l/min lminimal flow > 0,5l/min lclosed system .. amount of metabolized O2 Vaporizer – easy model Obsah obrázku interiér, stůl, vsedě, přepážka Popis se vygeneroval automaticky. Obsah obrázku stůl Popis se vygeneroval automaticky. Obsah obrázku doprava, světlo, zastavit, vsedě Popis se vygeneroval automaticky. Vaporizers Energy is needed during evaporation. Q (termal energy from outside) T (the gas temperature is lower at the outlet than at the inlet) Compensation inside bimetal Totaly different one … Desfluran Breathing Circuit linspiratory valve lmanometr lY connector lexpiratory valve lvolumetr lCO2 absorber ltubes lAPL valve to rebreath expired gas without CO2 – low flow inspiratory + exp. valve 1 dirrection flow manometr Y connector, filter, tubing ISO volumetr CO2 absorber > tubing Obsah obrázku interiér, vsedě, stůl, malé Popis se vygeneroval automaticky. APL Works during manual ventilation only Adjustable Pressure Limiting valve l(APL, "pop-off" valve) lis located at a position such that it is in pneumatic conection with the breathing circuit only during manual ventilation llimits the amount of pressure buildup that can occur during manual ventilation. When the user adjusts the APL valve to trap more gas inside the breathing circuit, a spring inside the APL valve is compressed according to how much the user turns the APL valve. The degree of spring compression exerts a proportional force on a sealing diaphragm in the APL valve. The pressure inside the breathing circuit must generate a force that exceeds the spring compression force for the APL valve to open. As pressure continues to build from the combination of fresh gas flow and manual compression of the breathing bag, the opening pressure of the APL valve will be exceeded and excess gas will be vented to the scavenging system. Breathing Circuit Ventilation system lventilator (bellow, chamber) (Volum Controled Ventilation, (PCV) Vt 6 (..10) ml/kg, f according EtCO2, PEEP 5 fiO2 40% I:E 1:2 lmanualy - bag Ventilation system lpower source -gas -electricity -both lDrive Mechanism, Circuit degign -double-circuit ventilator (patient and drive gas) l Parametry na obrazovce ventilátoru Bellow Blease Genius MRI Scavenging system lKeep clean OR atmosphere Scavenging system Non rebreathing systems (do not learn) Monitoring system monere, "to warn" systematic control Patient monitoring has been a key aspect of anesthesiology since its beginnings as a medical specialty. Figure 30-1 Optical illusions. We perceive the circles to be different sizes because we infer the size by relative dimensions. The closeness of the smaller circles makes the inner circle appear smaller, and vice versa. The lines appear to be different sizes because we use straight-line perspective to estimate size and distance. This illusion reportedly does not work in cultures where straight lines are not used. Therefore, our internal perceptions lead us to err in estimating size and length. In the same way, the internal programming of our monitors can lead us to misinterpret results. Downloaded from: Miller's Anesthesia (on 12 March 2009 08:22 PM) © 2007 Elsevier Optical illusions … it is not possible without eye Monitoring 1) Presence of anesth. / nurse lAirway + Breathing -patent A. -quality of B., auscultation lCirculation -quality, f, CRT, color of skin, BP ldepth of A. –pupils, sweating, movement Goal: prevent problem >>>> Alarm <<<< < ?? What should I do ??> -notice -interpret -reaction = change something lalarm off? lchange limits of alarm? Auscultator + available lventilatory problem (bronchospasm, laryngospasm - LM) - SpO2, EtCO2, ECG detect problem easier than continual auscultation. Basic monitoring in case of Fail of Anest. Machine Manometr lPressure in cuff (tr. tube / TS kanyla) … 20 cm H2O lPressure in SGD cuff (LM, LT) < 60 cm H2O ECG lHeart Frequency lrhytm lextrasystols lST - ischemia FIGURE 28–30 Why the ECG is so small. Multiple resistances and capacitances in the body decrease the potential and distort the waveform before the EMF reaches the surface. Positioning of electrodes sinus rythm SVT: (no P, QRS narrow, regular) Fibrilation of Atrii irregular , QRS narrow Ventricular rythm Stimulation spike, komplex ECG … Heart frequency l45/min or 150/min or ?? Amann et al. BioMedical Engineering OnLine 2005 4:60 doi:10.1186/1475-925X-4-60 ECG – complication of monitoring lelectric interference () l50Hz coross ECG cabel lcabel as anntena (loop) lno signal 10s after defibrilation Figure 32-2 Effect of cuff size on manual blood pressure measurement. An inappropriately small blood pressure cuff yields erroneously high values for blood pressure because the pressure within the cuff is incompletely transmitted to the underlying artery. Downloaded from: Miller's Anesthesia (on 12 March 2009 08:22 PM) © 2007 Elsevier NIBP – effect of cuff size Figure 32-3 Comparison of blood pressure measurements by Korotkoff sounds and oscillometry. Oscillometric systolic blood pressure is recorded at the point where cuff pressure oscillations begin to increase, mean pressure corresponds to the point of maximal oscillations, and diastolic pressure is measured when the oscillations become attenuated. Note the correspondence between these measurements and the Korotkoff sounds that determine auscultatory systolic and diastolic pressure. (Redrawn from Geddes LA: Cardiovascular Devices and Their Applications. New York John Wiley, 1984, Fig 34-2. Reprinted by permission of John Wiley & Sons, Inc.) Downloaded from: Miller's Anesthesia (on 12 March 2009 08:22 PM) © 2007 Elsevier NIBP Complications : * Pain * Petechie * Edema of extremity * Venous stasis, thrombophlebitis * Peripheral neuropathy * Compartment syndrome lUneasy measurement lmovements ltransport lbradycardia < 40/min lobesity lshock - vasoconstriction IBP, Canylation of artery * real-time, beat to beat * rapid changes - drugs / mechanic * repeated bload samples [BGasses] * failure of NIBP * additional information from puls curve •Pulse Pressure Variation Figure 32-4 Percutaneous radial artery cannulation. A, The wrist is positioned and the artery identified by palpation. B, The catheter-over-needle assembly is introduced through the skin and advanced toward the artery. C, Entry of the needle tip into the artery is identified by the flash of arterial blood in the needle hub reservoir. D, The needle-catheter assembly is advanced at a lower angle to ensure entry of the catheter tip into the vessel. E, If blood flow continues into the needle reservoir, the catheter is advanced gently over the needle into the artery. F, The catheter is attached to pressure monitoring tubing while maintaining proximal occlusive pressure on the artery. Downloaded from: Miller's Anesthesia (on 12 March 2009 08:22 PM) © 2007 Elsevier Invasive Pressure a. radialis / a. femoralis / a. brachialis arterie – hose – cell – infusion (cont. flush of cannyla ml/h) lfluid is not compressible X air lcloat of blood / cranking increase ressistance !!Alarm!! Low BP Figure 32-1 Digital heart rate (HR) displays may fail to warn of dangerous bradyarrhythmias. Direct observation of the electrocardiogram (ECG) and the arterial blood pressure traces reveals complete heart block and a 4-second period of asystole, whereas the digital display reports an HR of 49 beats/min. Note that the ECG filter (arrow) corrects the baseline drift so that the trace remains on the recording screen. (From Mark JB: Atlas of Cardiovascular Monitoring. New York, Churchill Livingstone, 1998, Fig. 13-2.) HR: 49/min, ECG: AV blok III Figure 36-1 Oxygen transport cascade. A schematic view of the steps in oxygen transport from the atmosphere to the site of utilization in the mitochondrion is shown here. Approximate Po2 values are shown for each step in the cascade, and factors determining those partial pressures are shown within the square brackets. There is a distribution of tissue Po2 values depending on local capillary blood flow, tissue oxygen consumption, and diffusion distances. Mitochondrial Po2 values are depicted as a range because reported levels vary widely. (Adapted from Nunn JF: Nunn's Applied Respiratory Physiology, 4th ed. Boston, Butterworth-Heinemann, 1993.) Downloaded from: Miller's Anesthesia (on 12 March 2009 08:46 PM) © 2007 Elsevier O2 in the body Figure 36-1 Oxygen transport cascade. A schematic view of the steps in oxygen transport from the atmosphere to the site of utilization in the mitochondrion is shown here. Approximate Po2 values are shown for each step in the cascade, and factors determining those partial pressures are shown within the square brackets. There is a distribution of tissue Po2 values depending on local capillary blood flow, tissue oxygen consumption, and diffusion distances. Mitochondrial Po2 values are depicted as a range because reported levels vary widely. (Adapted from Nunn JF: Nunn's Applied Respiratory Physiology, 4th ed. Boston, Butterworth-Heinemann, 1993.) Oxygenation of tissues lmonitoring of inspired O2 lSpO2 lArterial blood gasses - low cardiac output and good oxygention function of lung Saturation, SpO2 A pulse oximeter is a particularly convenient noninvasive measurement instrument. Typically it has a pair of small light-emitting diodes (LEDs) facing a photodiode through a translucent part of the patient's body, usually a fingertip or an earlobe. One LED is red, with wavelength of 660 nm, and the other is infrared, 905, 910, or 940 nm. Absorption at these wavelengths differs significantly between oxyhemoglobin and its deoxygenated form; therefore, the oxy/deoxyhemoglobin ratio can be calculated from the ratio of the absorption of the red and infrared light. The absorbance of oxyhemoglobin and deoxyhemoglobin is the same (isosbestic point) for the wavelengths of 590 and 805 nm; earlier oximeters used these wavelengths for correction for hemoglobin concentration. Figure 36-10 Principle of pulse oximetry. Light passing through tissue containing blood is absorbed by tissue and by arterial, capillary, and venous blood. Usually, only the arterial blood is pulsatile. Light absorption may therefore be split into a pulsatile component (AC) and a constant or nonpulsatile component (DC). Hemoglobin O2 saturation may be obtained by application of Equation 19 in the text. (Data from Tremper KK, Barker SJ: Pulse oximetry. Anesthesiology 70:98, 1989.) Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Principle of pulse oximetry l1000 absorption of light of different wave lenght Light passing through tissue containing blood is absorbed by tissue and by arterial, capillary, and venous blood. Usually, only the arterial blood is pulsatile. Light absorption may therefore be split into a pulsatile component (AC) and a constant or nonpulsatile component (DC). Hemoglobin O2 saturation may be obtained by application of Equation 19 in the text. (Data from Tremper KK, Barker SJ: Pulse oximetry. Anesthesiology 70:98, 1989.)Odlišit pulzující = arteriální nepulzující = ..... absorbci světla Figure 30-34 Hemoglobin extinction curves. Pulse oximetry uses the wavelengths of 660 and 940 nm because they are available in solid-state emitters (not all wavelengths are able to be emitted from diodes). Unfortunately, HbCO and HbO2 absorb equally at 660 nm. Therefore, HbCO and HbO2 both read as Sao2 to a conventional pulse oximeter. In addition, Hbmet and reduced Hb share absorption at 660 nm and interfere with correct Sao2 measurement. (Courtesy of Susan Manson, Biox/Ohmeda, Boulder, Colorado, 1986.) Downloaded from: Miller's Anesthesia (on 20 March 2009 08:47 AM) © 2007 Elsevier 2 wavelength , 2 absorptions for Hb a HbO2 AC660 / DC660 S = ---------------- aprox. % HBO/(HB+HBO) AC940 / DC940 Figure 30-34 Hemoglobin extinction curves. Pulse oximetry uses the wavelengths of 660 and 940 nm because they are available in solid-state emitters (not all wavelengths are able to be emitted from diodes). Unfortunately, HbCO and HbO2 absorb equally at 660 nm. Therefore, HbCO and HbO2 both read as Sao2 to a conventional pulse oximeter. In addition, Hbmet and reduced Hb share absorption at 660 nm and interfere with correct Sao2 measurement. (Courtesy of Susan Manson, Biox/Ohmeda, Boulder, Colorado, 1986.) SpO2 = HbO2 = O2 in the tissue loxygenation, not ventilation, linaccuracy 5% Falsely low readings: lhypoperfusion lincorrect sensor application; lhighly calloused skin lmovement (such as shivering) Falsely high: l carbon monoxide poisoning Figure 36-11 Effect of pulse oximeter probe replacement on delay from onset of hypoxemia to a drop in the measured Spo2. During cold-induced peripheral vasoconstriction in normal volunteers, the onset of hypoxemia was detected more quickly using an oximeter probe on the forehead compared with the finger. Other studies have shown a similar advantage for pulse oximeter probes placed on the ear. (From Bebout DE, Mannheimer PD, Wun C-C: Site-dependent differences in the time to detect changes in saturation during low perfusion. Crit Care Med 29:A115, 2002.) Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier SpO2 and low temperature Ventilation lP,V, flow; lPV curve lGas Analysis -O2, -EtCO2 – capnometry -N2O, [%] volatile anesthetics Parametry na obrazovce ventilátoru Flow Figure 36-24 Flow (ordinate) versus volume (abscissa). A, Closed-chest positive-pressure ventilation under general anesthesia in a patient with severe airways obstruction and hyperinflation before surgery to reduce lung volume. The flow-volume curve shows inspiratory (negative) and expiratory (positive) flow on the ordinate, plotted clockwise from zero volume on the abscissa. Expiratory flow started with a sharp upward peak and then fell immediately to a low flow rate with convexity toward the volume axis, suggesting expiratory flow limitation. expiratory flow rate was so low that inflation of the next positive-pressure breath was initiated before expiratory flow reached zero. Because expiratory flow continued up to this point, there must have been intrinsic positive end-expiratory pressure (PEEPi). B, A similar closed-check flow-volume curve after lung resection shows that the characteristic pattern of expiratory flow limitation has disappeared and that expiratory flow rate fell to zero before inflation started for the next breath (i.e., no suggestion of PEEPi). (Adapted from Dueck R: Assessment and monitoring of flow limitation and other parameters from flow/volume loops. J Clin Monit Comput 16:425, 2000.) Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Figure 57-1 Change in total respiratory compliance during pneumoperitoneum for laparoscopic cholecystectomy. The intra-abdominal pressure was 14 mm Hg, and the head-up tilt was 10 degrees. The airway pressure (Paw) versus volume (V) curves and data were obtained from the screen of a Datex Ultima monitoring device. Curves are generated for before insufflation (A) and 30 minutes after insufflation (B). Values are given for tidal volume (TV, in mL); peak airway pressure (Ppeak, in cm H2O); plateau airway pressure (Pplat, in cm H2O); total respiratory compliance (C, in mL/cm H2O); and end-tidal carbon dioxide tension (PetCO2, in mm Hg). Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier PV curve during capnoperitoneum Flow in time Výsledek obrázku pro airway flow in time Výsledek obrázku pro airway flow in time Pressure Flow Gas analyzers Main-stream Side-stream only CO2, méně přesné zpoždění light Monitoring of gas Main-stream Side-stream Figure 36-13 Paramagnetic oxygen analyzer. Two sealed spheres filled with nitrogen are suspended in a magnetic field. Nitrogen (N2) is slightly diamagnetic, and the resting position of the beam is such that the spheres are displaced away from the strongest portion of the field. If the surrounding gas contains oxygen, the spheres are pushed further out of the field by the relatively paramagnetic oxygen. The magnitude of the torque is related to the paramagnetism of the gas mixture and is proportional to the partial pressure of oxygen (Po2). Movement of the dumbbell is detected by photocells, and a feedback current is applied to the coil encircling the spheres, returning the dumbbell to the zero position. The restoring current and output voltage are proportional to the Po2. (Courtesy of Servomex Co., Norwood, MA.) Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier O2 paramagnetic gas (side stream monitor) Minimal fiO2: 21% safe 30% usualy : up to 60% in case of hypoxy: 100% preoxygenation: 100% Capnometr, Capnograph lInfra-red Spectrography http://www.capnography.com/Physics/Physicsphysical.htm CO2 emits IR radiation Figure 36-18 Examples of capnograph waves. A, Normal spontaneous breathing. B, Normal mechanical ventilation. C, Prolonged exhalation during spontaneous breathing. As CO2 diffuses from the mixed venous blood into the alveoli, its concentration progressively rises (see Fig. 36-19). D, Increased slope of phase III in a mechanically ventilated patient with emphysema. E, Added dead space during spontaneous ventilation. F, Dual plateau (i.e. tails-up pattern) caused by a leak in the sample line.325 The alveolar plateau is artifactually low because of dilution of exhaled gas with air leaking inward. During each mechanical breath, the leak is reduced because of higher pressure within the airway and tubing, explaining the rise in the CO2 concentration at the end of the alveolar plateau. This pattern is not seen during spontaneous ventilation because the required increase in airway pressure is absent. G, Exhausted CO2 absorbent produces an inhaled CO2 concentration greater than zero. H, Double peak for a patient with a single lung transplant. The first peak represents CO2 from the transplanted (normal) lung. CO2 exhalation from the remaining (obstructed) lung is delayed, producing the second peak. I, Inspiratory valve stuck open during spontaneous breathing. Some backflow into the inspired limb of the circuit causes a rise in the level of inspired CO2. J, Inspiratory valve stuck open during mechanical ventilation. The "slurred" downslope during inspiration represents a small amount of inspired CO2 in the inspired limb of the circuit. K and L, Expiratory valve stuck open during spontaneous breathing or mechanical ventilation. Inhalation of exhaled gas causes an increase in inspired CO2. M, Cardiogenic oscillations, when seen, usually occur with sidestream capnographs for spontaneously breathing patients at the end of each exhalation. Cardiac action causes to-and-fro movement of the interface between exhaled and fresh gas. The CO2 concentration in gas entering the sampling line therefore alternates between high and low values. N, Electrical noise resulting from a malfunctioning component. The seemingly random nature of the signal perturbations (about three per second) implies a nonbiologic cause. Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Figure 36-18 Examples of capnograph waves. A, Normal spontaneous breathing. B, Normal mechanical ventilation. C, Prolonged exhalation during spontaneous breathing. As CO2 diffuses from the mixed venous blood into the alveoli, its concentration progressively rises (see Fig. 36-19). D, Increased slope of phase III in a mechanically ventilated patient with emphysema. E, Added dead space during spontaneous ventilation. F, Dual plateau (i.e. tails-up pattern) caused by a leak in the sample line.325 The alveolar plateau is artifactually low because of dilution of exhaled gas with air leaking inward. During each mechanical breath, the leak is reduced because of higher pressure within the airway and tubing, explaining the rise in the CO2 concentration at the end of the alveolar plateau. This pattern is not seen during spontaneous ventilation because the required increase in airway pressure is absent. G, Exhausted CO2 absorbent produces an inhaled CO2 concentration greater than zero. H, Double peak for a patient with a single lung transplant. The first peak represents CO2 from the transplanted (normal) lung. CO2 exhalation from the remaining (obstructed) lung is delayed, producing the second peak. I, Inspiratory valve stuck open during spontaneous breathing. Some backflow into the inspired limb of the circuit causes a rise in the level of inspired CO2. J, Inspiratory valve stuck open during mechanical ventilation. The "slurred" downslope during inspiration represents a small amount of inspired CO2 in the inspired limb of the circuit. K and L, Expiratory valve stuck open during spontaneous breathing or mechanical ventilation. Inhalation of exhaled gas causes an increase in inspired CO2. M, Cardiogenic oscillations, when seen, usually occur with sidestream capnographs for spontaneously breathing patients at the end of each exhalation. Cardiac action causes to-and-fro movement of the interface between exhaled and fresh gas. The CO2 concentration in gas entering the sampling line therefore alternates between high and low values. N, Electrical noise resulting from a malfunctioning component. The seemingly random nature of the signal perturbations (about three per second) implies a nonbiologic cause. Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Normal ventilation spont. mandatory Figure 36-18 Examples of capnograph waves. A, Normal spontaneous breathing. B, Normal mechanical ventilation. C, Prolonged exhalation during spontaneous breathing. As CO2 diffuses from the mixed venous blood into the alveoli, its concentration progressively rises (see Fig. 36-19). D, Increased slope of phase III in a mechanically ventilated patient with emphysema. E, Added dead space during spontaneous ventilation. F, Dual plateau (i.e. tails-up pattern) caused by a leak in the sample line.325 The alveolar plateau is artifactually low because of dilution of exhaled gas with air leaking inward. During each mechanical breath, the leak is reduced because of higher pressure within the airway and tubing, explaining the rise in the CO2 concentration at the end of the alveolar plateau. This pattern is not seen during spontaneous ventilation because the required increase in airway pressure is absent. G, Exhausted CO2 absorbent produces an inhaled CO2 concentration greater than zero. H, Double peak for a patient with a single lung transplant. The first peak represents CO2 from the transplanted (normal) lung. CO2 exhalation from the remaining (obstructed) lung is delayed, producing the second peak. I, Inspiratory valve stuck open during spontaneous breathing. Some backflow into the inspired limb of the circuit causes a rise in the level of inspired CO2. J, Inspiratory valve stuck open during mechanical ventilation. The "slurred" downslope during inspiration represents a small amount of inspired CO2 in the inspired limb of the circuit. K and L, Expiratory valve stuck open during spontaneous breathing or mechanical ventilation. Inhalation of exhaled gas causes an increase in inspired CO2. M, Cardiogenic oscillations, when seen, usually occur with sidestream capnographs for spontaneously breathing patients at the end of each exhalation. Cardiac action causes to-and-fro movement of the interface between exhaled and fresh gas. The CO2 concentration in gas entering the sampling line therefore alternates between high and low values. N, Electrical noise resulting from a malfunctioning component. The seemingly random nature of the signal perturbations (about three per second) implies a nonbiologic cause. obstruction of airway expirium inspirium Figure 36-19 Mechanisms of airways obstruction producing an upsloping phase III capnogram. In a normal, healthy person (upper panel), there is a narrow range of [Vdot]a/[Qdot] ratios with values close to 1. Gas exchange units therefore have similar Pco2 and tend to empty synchronously, and the expired Pco2 remains relatively constant. During the course of exhalation, the alveolar Pco2 slowly rises as CO2 continuously diffuses from the blood. This causes a slight increase in Pco2 toward the end of expiration, and this increase can be pronounced if the exhalation is prolonged (see Fig. 36-18C). In a patient with diffuse airways obstruction (lower panel), the airway pathology is heterogeneous, with gas exchange units having a wide range of [Vdot]a/[Qdot] ratios. Well-ventilated gas exchange units, with gas containing a lower Pco2, empty first; poorly ventilated units, with a higher Pco2, empty last. In addition to the continuous rise in Pco2 mentioned previously, there is a progressive increase caused by asynchronous exhalation. Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Figure 57-2 Ventilatory changes (pH, Paco2, and PetCO2) during CO2 pneumoperitoneum for laparoscopic cholecystectomy. For 13 American Society of Anesthesiologists (ASA) class I and II patients, minute ventilation was kept constant at 100 mL/kg/min with a respiratory rate of 12 per minute during the study. Intra-abdominal pressure was 14 mm Hg. Data are given as the mean ± SEM.*, P .05 compared with time 0. Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier CO2 during Capnoperitoneum Figure 36-20 The effect ofNaHCO3- administration on end-tidal Pco2. A continuous tracing of end-tidal Pco2 is shown as a function of time. Intravenous administration of 50 mEq followed by 30 mEq of NaHCO3 results in an abrupt increase in expired CO2 because of neutralization of bicarbonate by hydrogen ions. Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Capnograph Sudden fall to 0: lno ventilation - obstruction lerror gradual decrease: lpartial obstruction lhyperventilation ldecrease of metabolism ldecrease of perfusion of the lung 0 etCO2 lintubation to oesophagus Body temperature l> 60 minut in anesthesia lchildren lactive warming – bed, warm air Figure 40-7 Hypothermia during general anesthesia develops with a characteristic pattern. An initial rapid decrease in core temperature results from a core-to-peripheral redistribution of body heat. This redistribution is followed by a slow, linear reduction in core temperature that results simply from heat loss exceeding heat production. Finally, core temperature stabilizes and subsequently remains virtually unchanged. This plateau phase may be a passive thermal steady state or might result when sufficient hypothermia triggers thermoregulatory vasoconstriction. Results are presented as means ± SD. Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Redistribution of heat peripheral vasodilatation Lower generation of heat constant heat loss New steady state 15 minutes after EPI anestesia: decrease in core temperature, increase in feeling of thermal comfort (visual analog scale -VAS). Interestingly, however, maximal thermal comfort coincided with the minimum core temperature. Tympanally measured temperature. (Redrawn with modification from Sessler DI, Ponte J: Shivering during epidural anesthesia. Anesthesiology 72:816-821, 1990.) Downloaded from: Miller's Anesthesia (on 19 March 2009 11:18 PM) © 2007 Elsevier Monitoring of muscle block * single-twitch * train-of-four (TOF) * tetanic, post-tetanic count (PTC) * double-burst stimulation (DBS) Single-twitch * 1Hz .. 0,1Hz, continually Figure 39-1 Pattern of electrical stimulation and evoked muscle responses to single-twitch nerve stimulation (at frequencies of 0.1 to 1.0 Hz) after injection of nondepolarizing (Non-dep) and depolarizing (Dep) neuromuscular blocking drugs (arrows). Note that except for the difference in time factors, no differences in the strength of the evoked responses exist between the two types of block. Downloaded from: Miller's Anesthesia (on 12 March 2009 08:46 PM) TOF * 4 stimuls á 0,5s (2Hz) Downloaded from: Miller's Anesthesia (on 12 March 2009 08:46 PM) Figure 39-2 Pattern of electrical stimulation and evoked muscle responses to TOF nerve stimulation before and after injection of nondepolarizing (Non-dep) and depolarizing (Dep) neuromuscular blocking drugs (arrows). Tetanic stimulation * painfull; * 50Hz na 5s Figure 39-3 Pattern of stimulation and evoked muscle responses to tetanic (50-Hz) nerve stimulation for 5 seconds (Te) and post-tetanic stimulation (1.0-Hz) twitch. Stimulation was applied before injection of neuromuscular blocking drugs and during moderate nondepolarizing and depolarizing blocks. Note fade in the response to tetanic stimulation, plus post-tetanic facilitation of transmission during nondepolarizing blockade. During depolarizing blockade, the tetanic response is well sustained and no post-tetanic facilitation of transmission occurs. Downloaded from: Miller's Anesthesia (on 12 March 2009 08:46 PM) © 2007 Elsevier Posttetanic facilitation Figure 39-4 Pattern of electrical stimulation and evoked muscle responses to TOF nerve stimulation, 50-Hz tetanic nerve stimulation for 5 seconds (TE), and 1.0-Hz post-tetanic twitch stimulation (PTS) during four different levels of nondepolarizing neuromuscular blockade. During very intense blockade of the peripheral muscles (A), no response to any of the forms of stimulation occurs. During less pronounced blockade (B and C), there is still no response to stimulation, but post-tetanic facilitation of transmission is present. During surgical block (D), the first response to TOF appears and post-tetanic facilitation increases further. The post-tetanic count (see text) is 1 during intense block (B), 3 during less intense block (C), and 8 during surgical block (D). Downloaded from: Miller's Anesthesia (on 12 March 2009 08:46 PM) © 2007 Elsevier Double-burst stimulation * 2 short sequences of 50-Hz tetanic stimulation, separated by 750 ms pause * nonrelaxed muscle – 2 equal contractions * patialy relaxed m. – 2nd contr. is weaker Figure 39-7 Pattern of electrical stimulation and evoked muscle responses to TOF nerve stimulation and double-burst nerve stimulation (i.e., three impulses in each of two tetanic bursts, DBS3,3) before injection of muscle relaxants (control) and during recovery from nondepolarizing neuromuscular blockade. TOF ratio is the amplitude of the fourth response to TOF divided by the amplitude of the first response. DBS3,3 ratio is the amplitude of the second response to DBS3,3 divided by the amplitude of the first response. (See text for further explanation.) Downloaded from: Miller's Anesthesia (on 12 March 2009 09:47 PM) © 2007 Elsevier Awarrenes during GA lto remember moments of GA l0,1 – 0,2% population (1:800) -Extracorporal circulation -Caesarean operation -trauma report: -filling of weakness, unable to move -conversation -anxiety, pain, powerlessness Monitoring of depth of anaesthesia lEEG – matematics → BIS .. Level of awareness 100 .. 0 Next? ... pharmacology