B3 SIM Lab ICM · 2021. 1. 17. · Title: Microsoft Word - B3 SIM Lab ICM.docx Author: mmlcek Created Date: 3/12/2017 5:01:02 PM

Phys SIM Labs B3 – ICM Basics ver 12032017 Page | 1

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Handout

SIM Lab: ICM Basics ICM = Intensive Care Medicine

THIS TEXT WILL BE UPDATED BY MAR 21

3. Blok (LS)

Here you find some self-study notes for ICM SIM Lab

List of competencies Block 1: Intensive Care Monitoring – Respiration, Capnography, BP Block 3: Basics of Advanced life support

The information provided here is simplified, tailored for the purpose of Physiology SIM Labs The more you know before coming to the SIM lab, the more time we can spend hands-on… ;-)

Thanks to Michal Pisinger for the translation.


KNOWLEDGE AND GOALS Required knowledge: SIM I1, B1 , B2, I2: Basic examination of the patient without aids including hearing. Evaluating conditions. SBAR. Examination with aids: ECG, NIBP, SpO2, basics of capnometry. Normal ranges of parameters. Basics of respiratory regulation. Basics of measuring IBP, normal curve. Basics of respiratory masks, giving O2. First aid: BLS, AED Goals:

The basics of anesthesia, resuscitation, and intensive care. (On simulations) o Continual monitoring of patients in anesthesia or in intensive conditions, evaluating

conditions o Recognizing serious/critical situations and timely decisions to intervention, o Execution of some interventions, principles

Cooperation in a group, basics of CRM (crisis resource management). The dynamics of conditions; integrating other physiological parameters.

Purpose: To prepare for practicals with anesthetized rats, where we cannot rule out life threatening

complications. To illustrate the context of physiological functions and parameters on clinical cases.

Knowledge (after completing the lab): Knowledge of principles and usage of all listed parameters, methods of monitoring and interventions. 1. Vital monitoring. Orientation on an expanded monitor of an intensively monitored patient (ECG,

IBP, CVP, SpO2, RR, capno, T). Principles, context, norms, indications, limits. a. CVP is a relatively easy to monitor parameter. Is an indicator of (-volemia, preload,

pumping function of the right heart). b. ARTerial pressure in serious disorders of hemodynamics commonly needs to be

measured invasively (advantages: continual measuring, reliable even with very low values)

c. Respiration (RR) can be continually monitored with capnometry or impedance. d. Capnometry (CO2) allows evaluating the adequacy of ventilation, along with diffusion

and perfusion. 2. Urgent conditions: circulatory and respiratory arrest.

a. Deciding when to begin and end urgent resuscitation (monitored patient) b. Basics of expanded resuscitation (ALS), execution c. Defibrillation - principle, indication (rhythms which can be defibrillated)

3. Anesthesia (general) a. Anesthetics commonly inhibit the respiratory center. The result of that can be hypoxia

and cardiac arrest. b. Anesthetics may inhibit the vasomotor center and ANS. That can lead to hypotension,

bradycardia, ev. cardiac arrest. It can even prevent the manifestation of a stress reaction (↑HR a BP).

c. Anesthesia is risky => need to monitor continually 4. Serious conditions (bradycardia, hypoxia, hypotension, dehydration/hypovolemia, insufficient

analgosedation). Recognition, principles of correction, chosen reactions. a. Generally in hypoxia (SpO2 < 95% *) you need to give oxygen. b. Hypoxia and pain significantly stimulate the sympathicus.


BLOK 1 = Continuous Monitoring, Response The basics of examination and monitoring (ECG, SpO2, NIBP, T) which have been repeatedly gone through. Now we'll complete respiration and pressure.

1. Monitoring respiration.

RR imp - measuring respiratory rate with impedance

After connecting ECG leads, not only will you see an ECG curve on the patient monitor, but also the value of respiratory rate, maybe even a respiratory curve. The monitor determines these values on the basis of continually measuring electrical conductance of the thorax (more precisely impedance). The change of conductance here is because of the change of air in the lungs (more air = less conductance). This method is very useful as a continual record of respiratory rate. However, it isn't sufficiently precise and robust, so you cannot measure spirometric parameters (lung volumes and flow) from the impedance curve. Questions, tasks

Measure RR imp on yourselves (one from the group) with the help of a patient monitor.

Why isn't RR imp a useful method for measuring ventilation? [Impedance is greatly influenced by many factors other than just breathing. The amount of water/blood, resistance of electrodes, movement, … They're involved in every measurement of impedance]

Ventilation

In patients with artificial ventilation, the ventilator measures many parameters including pressure in airways (Paw) and flow (from this we can for example calculate minute ventilation (MV). These parameters cannot be continually measured other than with a ventilator. Questions, tasks

Examine the circle of the ventilator

Capnography (provides the parameters RR aw, etCO2)

Methods which provide a lot of information, for example respiratory rate (RRaw) and alveolar concentration (etCO2), which shows the adequacy of ventilating relative to metabolic demands. What is it: Continual record of pCO2 in air which we are breathing (inhalation and exhalation). etCO2 depends esp. on: i) production of CO2, ii) circulation - bringing CO2 into the lungs iii) pulmonary diffusion, iv) minute ventilation see the diagram. Significance: Especially evaluating the adequacy of ventilation. ATTENTION, capno also depends on perfusion and others see below. Normal values cca 40 +/- 4 mmHg (cca 5.2 kPa) Indication: in all patients with secured airways, when ventilating with a mask (not always, but is becoming more common) Principle: CO2 is calculated spectophotometrically (infrared) in the air, which flows through a breathing tube. The sensor is located in a way that it can continually sample inhaled and exhaled air. (Where is it?) The output is typically: i) curve of pCO2 over time ii) value of pCO2 at the end of exhalation (EtCO2) iii) respiratory rate value (RR)

Capnometry is an analogous method, however, it only provides EtCO2 a RR, not a curve (graph).


Questions, tasks

Measure capnography (one from the group), notice the values of etCO2 and RRaw. Reach hypo- and hypercapnia. What influences the value of EtCO2: (for starters evaluate every parameter individually)

o Circulatory arrest o Defect of pulmonary diffusion, o Hyperventilation, o Hypoventilation. o Disproportion of ventilation-perfusion

2. Monitoring blood pressure (NON/INVASIVE)

NONINVASIVE:

CVP can be roughly estimated just by looking at the filling level of the neck veins. It isn't very handy for continual monitoring.

ARTerial pressure can be monitored noninvasively with a cuff from the patient monitor, which can be programmed to repeatedly measure in intervals according to need (typically minutes up to hours) Output: SYS/DIA (mean)


INVASIVE: Invasive (direct, bloody) measuring of pressure is directly in the blood vessels (ev. heart). Significance: i. Continual measurement (important especially in failing circulation).

ii. Reliable measuring even in very low pressure (for ex. in shock), when measuring with a cuff is complicated. iii. Is the only precise method of measuring CVP

Principle: percutaneous introduction of catheter into blood vessels. The sensor is usually on the outside of the patient's body, at heart level Why?. The sensor and catheter are connected with a tube (similar to a saline one) filled with physiological solution which must be without air (vented) Why?.

Central venous pressure (CVP)

CVP is the pressure in large veins at heart level. CVP depends mostly on i) venous return, ii)filling of blood vessels and iii) pumping function of the right heart iv) venous tone/pressure of the thorax Significance: Lowered values CVP are for example in hypovolemia, lowered return, increased during hypervolemia and conditions, where the heart is failing to pump blood. It's possible to come up with it ;-) Normal values of CVP are around 2-8 mmHg.

CVP - Execution

For measuring CVP, it is necessary to introduce a catheter where the distal end is in the caval vein at heart level. The typical access point is the jugular or subclavial vein. Cathetrization of central veins is mostly standard in many departments because of long term infusion therapy, parenteral nutrition etc. (ICU, surgery, ARO). Cathetrization of central veins carries certain risks (infections, thrombosis, pneumothorax during introduction). It must be smaller than expected benefit.

Output of invasive measuring CVP is a curve on the monitor labelled as CVP and a numbered value of mean pressure, typically in mmHg.

Arterial blood pressure (ABP, ART, RAD, FEM, Ao, …)

ART is the pressure in the arterial vessels (at the end of the catheter, but it is relative to heart level) ART typically depends on: i) cardiac output, ii) peripheral vascular resistance, iii) volume of circulating fluids Significance: evaluating hemodynamics, managing treatment with vasopressors, estimating organ perfusion Indications: Hemodynamically unstable patients (ICU, ARO, operations), cardiovascular operations Risks. Injuring arteries, ischemia of vessels, air embolism, bleeding. Risks are bigger than in CVP and must be assessed against benefit. In unstable hemodynamics, IBD is completely indicated. Output of invasive measuring ART is a curve on the monitor labelled as ABP or ART or according to the respective artery, RAD, FEM, Ao, PAP,… or heart section (LVP, RVP, RAP …) along with numbered values of SYS/DIA (mean), typically in mmHg.


Questions, tasks: Examine the model of direct blood pressure measurement. Try changing the position of the

sensor and aeration to see how it affects measurement. Color the ART curve (from memory). Why is measuring art more dangerous than CVP? Why must the sensor for IBP be at heart level while a sphygmomanometer for NIBD doesn't? What is the difference between a IBP curve and SpO2 (more precisely plethysmographic)? What is "zeroing pressure“? [calibrating the sensor according to atmosphere. Atmospheric

pressure is set as 0 mmHg] Can coagulation/thrombosis endanger the catheter, embolism/thrombosis of blood vessels?

[YES. The catheter is usually continually flushed by a physiological solution with heparin. Very slowly]

Would you be capable of willfully changing your CVP value? Note: The sensor must be zeroed to the value of atmospheric pressure before introduction

(also continually).


3. ICM TROUBLESHOOTING HINTS (monitored patient) In patients who are monitored continuously the decision making process differs from Basic Life Support algorithms. In monitored patients there often is a lot more reliable data available - both anamnestic and real-time, continuous. Thus the priority often is checking CIRCULATION (vs. BREATHING in BLS) The table below gives brief overview how to assess and troubleshoot various issues in intensive care. This is NOT an algorithm or prioritized list. Thus it is essential to understand the principles to be able to respond adequately in various circumstances.

Symptom Check Possible solutions (FIX TECH. ISSUES FIRST)

D danger

Many… Don't underestimate unexpected risks.

R response

Movement Pain response

Reaction to pain (depth of anesthesia)

Pulse, pressure

Consider deepening anesthesia

A airway

WHEEZING NOT BREATHING

Airways (head-tilt, secretion, aids securing airways)

Head-tilt Sucking up secretion of

airways

B breathing

still NOT BREATHING NORMALLY

Mask + resusci bag Breathing tube (airtight?) Ventilator

Begin breathing with bag

C circulation

Signs of arrest HR < ~40 bpm Cyanosis/pale

ECG, skin color, pulse, pressure Quality of monitoring

CPR Circulation Support?

ECG unreadable VT/VF HR < ~40 bpm

Attachment of electrodes. Gel? Settings of leads Manipulation with the patient?

Tremor?

VF/VT => CPR + DEFI Circulation support (HR)

SpO2 < 95% Signal Low Inaccessible 100%

Attachment of sensor Peripheral hypoperfusion? (cold

extremities, hypotension, strangulation,..)

Breathing incl. hearing Inhaled oxygen (FiO2)

Options: Secure airways Administer O2 Ventilation support Circulation Support Treat acral parts

BP Not recording High Low

Cuff Link IBP Manipulation/is the patient moving?

Options in hypotension: Administer fluids Cardiac support Vasopressors Options in hypertension: Remove Stressor Vasodilation

etCO2 Not recording High Low

Location of the sensor Breathing circuit tight? (no leak?) Breathing incl. auscultation Hemodynamics Metabolism

-> ventilation adjust. -> hemodynamic support -> see later.

T Low (High) Check thermometer location Check thermometer connection

Warm up (solutions, air)


BLOCK 2 = ICM Simulations

This part is aimed at experiential learning and has no self-study text.

Basic competencies in simulation medicine and relevant chapters from ALS and Physiology are expected (See the Knowledge section above.)


BLOCK 3 = ALS essentials We presume the knowledge of basics life suppotr (BLS). Let's shortly summarize some differences between ALS and BLS. The essential difference is that in ALS we have various aids at hand, often including monitoring. Priorities based on urgency:

Recognizing cardiac arrest. Beginning chest compression. Connecting a monitor/defibrillator - timely defibrillation (if it is indicated). Ventilation Oxygenation, eventually securing the airways Getting entry into the vasculature, pharmacological support. The main priority is circulation, but we often make our decisions based on ventilation. That may cause

confusion.

1. Recognizing cardiac arrest and deciding to initiate resuscitation In real life situations the decisions aren't that trivial even for professionals. Decisions is mainly based on: 4. Presence of unconsciousness (however in patients under anesthesia this isn't really meaningful) 5. ECG: asystole or ventricular fibrillation (VF) 6. ECG + central pulse in other rhytms when we suspect circulatory arrest. Note: If we don't have machines: the way we make our decisions is like in BLS. Gasping or no breathing (not checking pulse)

2. Chest compression

7. The principles and procedure are the same as in BLS: o Begin as soon as possible trying to substitute the mechanical function of the heart, therefore

securing circulation o It is vital to compress with the minimal amount of interruptions. How see below.

8. There is a difference from BLS if we are simultaneously ventilating with a bag and mask: o Ratio of compressions:breaths is 30:2 o during inspirations we interrupt the compressions for about 5 s.

3. Defibrillation The principle of defibrillation is a discharge which causes a synchronized depolarization of all

cardiomyocytes that then become refractory, thus an opportunity appears of making a new heart rhythm capable of generating perfusion (ideally a sinus one).

Defibrillation therefore has a purpose if the electrical activity of the ventricles is preserved which is albeit chaotic or quite fast (more than the max. effective frequency). We call these rhythms defibrillatable rhythms: o ventricular fibrillation (VF) o ventricular tachycardia without an effective circulation (pVT).

Defibrillation is not indicated (is not meaninfful) in: o asystole (no electrical activity – there is nothing to synchronize) o arrests with a normal or organized rhythm (this already are synchronous, so nothing to

synchronize) o severe bradycardia or blocks (also is synchronous)

Defibrillation must occur as soon as possible, but it is usually preceded by compressions (before a defibrillator is available).

Beware! Timely defibrillation increases secondary survival with a good neurological result in up to 40 % (in asystole it is 6-15 %).

How see further studies.


4. Ventilation In sudden cardiac arrests tha tis witnesssed or the duration is short and clearly documented it is

possible to omit ventilations for about 5 minutes (cf. O2 stores in the body and also gasping). We can ventilate with a bag or ventilator through a mask or with another aid that secures the airways. Ventilation with a bag and a mask is done synchronically with compressions with a ratio of 30:2 A breath should last at max.1s, interrupting compressions at max. 5s. Ventilating with a positive overpressure isn't physiological and has its risks:

o worsens venous return o may lead to an inflation of the stomach with a risk of aspiration.

How to ventilate with a mask see the introductory lab protocol for the summer semester. Beware! The preparation of a resuscitation bag or securing the airways musn't delay the start of chest

compressions or cause long term interruptions.

5. Teamwork We can presume that in ALS there will be a cooperation of some professionals. For teamwork to be effective, it must be coordinated (and practiced). Otherwise a group can be counterproductive. Managing critical situations in medicine is for now partly neglected. It's called CRM (crisis resource management) and it has sophisticated methodics, especially in the military, and critical . Here are just the principles, the details will be in higher grades. And what is even more important here is practice

One leads regardless the number of team members. Ideally the leader doesn't do anything else. If 2 rescuers:

o the leader is behind the head, monitors, ventilates and compresses the chest o the second member of the team does everything else (see below)

If more rescuers: o one monitors breathing and circulation - if the team is small, it is always the leader o one provides ventilation, takes care of the airways, eventually secures them with aids (this is

also usually done by the leader, who again is standing behind the head) o one simply compresses the chest. o one connects and works with the monitor along with the defibrillator o one secures the entrance to the vasculature and administeres drugs per instruction by MD o eventually one takes care of the protocol

More on Chest Compressions The main goal is to substitute the function of the mechanical function of the heart as soon as possible, Compressions by themselves usually don't renew heart functions. Procedure:

o Begin immediately, definitely and without delay o In the middle of the chest, between the nipples, straight down. (Compare the location of the heart in

the chest) We usually compress with both of our palms together. What is significant is obviously the result, not the technique. (it's possible to do it with one hand, two hands, from the side, head…)

o Depth 5-6 cm, child 1/3 anteroposterior line of the chest. Beware! insufficient depth decreases effectiveness significantly.

o Frequency 100 – 120 /min Beware! Slow frequencies cause an insufficient cardiac output, the return is quite fast and insufficient along with the filling of the heart.

o Do not interrupt (or for just a few seconds only!). Beware! There needs to be a sufficient pressure for perfusion. The pressure becomes sufficient after about 1 minute of good uninterrupted compressions, During interruptions the pressure falls to zero after a few seconds. That's why it's very important not to interrupt compressions and to uphold the ratio of compressions:ventilation 30:2 (compared to the former 5:1 or 15:2).


Did you get stuck? Try the concept "10 seconds -for-10 minutes“ (M. Rall, modified)h

1. Problem?

Ask yourself and all of your team members, ‘What is the biggest problem right now?’ – ‘What is the most dangerous aspect of the problem?’ (‘What outcome would I like to have least?’).

2. Opinions? Clarify the above with all available team members. 3. Facts? Gather available information. 4. Plan?

Using input from the team, make a treatment plan. This includes the plan as well as the sequence of actions. On many occasions we observed team leaders giving orders as ideas came to mind, not necessarily in order of priority.

5. Distribute?

Distribute the workload by assigning tasks and responsibilities. This may include such activities as reporting on thresholds, e.g.: ‘Keep an eye on O2 saturation and let me know if it falls below 94%.’

6. Check!

Before diving into work, involve all team members again to encourage them to raise any further concerns or suggestions for improvement or refinement.

Documents

B3 SIM Lab ICM · 2021. 1. 17. · Title: Microsoft Word - B3 SIM Lab ICM.docx Author: mmlcek Created Date: 3/12/2017 5:01:02 PM