Category Archives: Critical Care

Critical Care: Emergency Medications

I. SODIUM CHANNEL BLOCKERS – ↓ conduction velocity in the atria, ventricles, His-Purkinje

  • Class 1A: Norpace/disopyramide, Pronestyl/procainamide, Quinora/quinidine
    – action: delays repolarization
    – effect on EKG: wide QRS, prolonged QT
  • Class 1B: Xylocaine/lidocaine, Mexitil/mexiletine, Dilantin/phenytoin
    – action: accelerates repolarization
    – effect on EKG: little to no effect
  • Class 1C: Tambocor/flecainide, Rythmol/propafenone
    – action: decreases impulse conduction
    – effect on EKG: pronounced prodysrhythmic actions, wide QRS, prolonged QT

II. BETA ADRENERGIC BLOCKERS

  • Tenormin/atenolol, Coreg/carvedilol, Brevibloc/esmolol, Lopressor/metropolol, Betapace/sotalol
    action: ↓ automaticity of SA node, ↓ conduction velocity of AV node,  atrial and ventricular contractility
    effect on EKG: bradycardia, prolonged PR, AV block

III. POTASSIUM CHANNEL BLOCKERS

  • Cordarone/amiodarone, Bretylol/bretylium, Tikosyn/dofetilide, Corvert/ibutilide, Betapace/sotalol
    action: delay repolarization, resulting in prolonged action potential and refractory period
    effect on EKG: prolonged PR and QT, wide QRS, bradycardia

IV. CALCIUM CHANNEL BLOCKERS

  • Cardizem/diltiazem, Calan/verapamil
    action: ↓ automaticity of SA node, delay AV node conduction, ↓ myocardial contractility
    effect on EKG: bradycardia, prolonged PR, AV block

V. OTHER

  • Adenocard/adenosine, Lanoxin/digoxin, Magnesium
    action: ↓ conduction through AV node, ↓ automaticity of SA node
    effect on EKG: prolonged PR, AV block
Image Source.
Content derived from Medical-Surgical Nursing: Assessment and Management of Clinical Problems, 8th Edition.
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Critical Care: Mechanical Ventilator Basics

I. MODES OF VENTILATION

  • Controlled: ventilator does the work of breathing (WOB) FOR the patient
  • Assist-control: patient and ventilator share WOB, patient initiates a spontaneous breath and a tidal volume is delivered
  • Synchronized Intermittent Mandatory Ventilation (SIMV): patient receives a preset tidal volume at a preset frequency, synchronous with the patient’s own breathing; patient can still breathe spontaneously in between ventilator breaths
  • Pressure support ventilation (PSV): positive airway pressure (PAP) applied during inspiration; patient must be able to initiate a spontaneous breath
  • Pressure-control inverse ratio ventilation (PC-IRV): prolonged PAP applied to increase inspiratory time and decrease expiratory time; normal inspiration/expiration (I:E) ratio is 1:2, with PC-IRV it is reversed to 2:3, 3:1, 4:1, etc1

II. VENTILATOR SETTINGS

  • Rate (f) – number of breaths per minute (usual: 6-20)
  • Tidal volume (Tv) – volume of air delivered with each breathe (usual: 6-10 mL/kg)
  • Fraction of Inspired Oxygen (FiO2) – oxygen concentration (usual: 21%-100%)
  • Positive End-Expiratory Pressure (PEEP) – positive pressure applied at the end of expiration (usual 5 cm H2O)
  • Pressure support – positive pressure applied to keep airway open and facilitate inspiration (usual: 6-18 cm H2O)
  • I:E ratio – inspiration:expiration ratio (usual: 1:2, 1:1.5), if IMV desired – 2:1, 3:1

III. VENTILATOR ALARMS

  • High pressure alarm: kinking of the tubing, patient biting on endotracheal (ET) tube, secretions pooling in tubing, patient “fighting” the ventilator, bronchospasms, pulmonary edema
  • Low pressure alarm: air leak from tube, ET tube cuff has deflated, total or partial extubation,

IV. PREVENTING VENTILATOR-ASSOCIATED PNEUMONIA (VAP)

  • Head-of-bed (HOB) elevated at minimum, 30-45 degrees
  • NO routine changes of ventilator circuit tubing
  • Use of an ET tube with dorsal lumen to facilitate suctioning
  • Hand hygiene

V. WEANING PARAMETERS

  • Negative Inspiratory Force (NIF) = 20-30
  • Minute ventilation (Ve) = < 10 L/min
  • Pressure of carbon dioxide (PaCO2) = 35-45 (or within normal limits [COPD patients])
  • Pressure of oxygen (PaO2) = 60+
  • Fraction of inspired oxygen (FiO2) = 50% or less
  • Positive end-expiratory pressure (PEEP) = < 5
  • Pressure support ventilation (PSV) = 10 or less

VI. COMPLICATIONS OF MECHANICAL VENTILATION

  • Decreased cardiac output due to increase intrathoracic pressure resulting from high PEEP
  • Barotrauma/volutrauma due to over distension of the lungs from high inspiratory pressures or high PEEP; can lead to pneumothorax
  • Hypo/hyperventilation which can lead to acid base imbalances
  • Ventilator-associated pneumonia (VAP)
  • Fluid and electrolyte imbalances due to low cardiac output, low kidney perfusion
Image Source.
Content derived from Medical-Surgical Nursing: Assessment and Management of Clinical Problems, 8th Edition.

Critical Care: Heart Blocks

**With heart blocks, the AV node is sick. Therefore the P-R INTERVAL will be abnormal.

I. FIRST DEGREE HEART BLOCK

  • HEART RATE: Variable
  • RHYTHM: Regular
  • P WAVES: Normal
  • P-R INTERVAL: consistently longer than 0.20 seconds
  • QRS WIDTH: Usually normal
  • INTERVENTIONS: Continue to monitor, IV, O2

II. SECOND DEGREE HEART BLOCK, TYPE I (WENCKEBACH, MOBITZ I)

  • HEART RATE: Variable
  • RHYTHM: Irregular
  • P WAVES: Normal; # of P’s > # of QRS
  • P-R INTERVAL: progressive lengthening on consecutive beats until you drop one QRS
  • QRS WIDTH: Usually normal, absent when blocked
  • INTERVENTIONS: Continue to monitor, IV, O2

III. SECOND DEGREE HEART BLOCK, TYPE II (MOBITZ II)

  • HEART RATE: Variable, slow
  • RHYTHM: Irregular
  • P WAVES: Normal; # of P’s > # of QRS
  • P-R INTERVAL: consistent when it happens, absent with blocked beats
  • QRS WIDTH: Usually normal, absent when blocked
  • INTERVENTIONS: transcutaneous pacemaker; *closely monitor, as it may lead to complete heart block!

IV. THIRD DEGREE (COMPLETE) HEART BLOCK

  • HEART RATE: Variable, slow
  • RHYTHM: Regular
  • P WAVES: Normal; # of P’s > # of QRS
  • P-R INTERVAL: Random
  • QRS WIDTH: Wide
  • INTERVENTIONS: transcutaneous pacemaker; may then need permanent pacemaker
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Critical Care: Atrial Rhythms

I. PREMATURE ATRIAL CONTRACTIONS (PACs)

  • HEART RATE: Variable
  • RHYHTM: Irregular
  • P WAVES: Abnormal configuration, 1:1 ratio
  • P-R INTERVAL: Variable, may be shorter
  • QRS WIDTH: Usually normal
  • INTERVENTIONS: Continue to monitor, check pulse

II. PAROXYSMAL/SUPRAVENTRICULAR TACHYCARDIA (P/SVT)

  • HEART RATE: 100-300
  • RHYTHM: Regular
  • P WAVES: Abnormal, may be hidden
  • P-R INTERVAL: Variable, may be hidden
  • QRS WIDTH: Usually normal
  • INTERVENTIONS: Continue to monitor, may use vagal maneuvers and adenosine, cardioversion if other measures are ineffective

III. ATRIAL FIBRILLATION

  • HEART RATE: Atrial – >350, Ventricular – depends on AV block
  • RHYTHM: Irregular
  • P WAVES: Fibrillatory waves, “scribble”
  • P-R INTERVAL: Absent
  • QRS WIDTH: Usually normal
  • INTERVENTIONS: Prevent clots with anticoagulants, rate control with calcium channel blockers

IV. ATRIAL FLUTTER

  • HEART RATE: Atrial – 250-300, Ventricular – depends on AV block
  • RHYTHM: Atrial – regular, Ventricular – varies with AV
  • P WAVES: “Sawtooth” flutter waves
  • P-R INTERVAL: Absent
  • QRD WIDTH: Usually normal
  • INTERVENTIONS: Prevent clots with anticoagulants, rate control with calcium channel blockers
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Critical Care: Sinus Rhythms

I. NORMAL SINUS

  • HEART RATE: 60-100
  • RHYTHM: Regular
  • P WAVES: Normal
  • P-R INTERVAL: Normal
  • QRS WIDTH: Normal
  • INTERVENTIONS: Continue to monitor, check pulse

II. SINUS BRADYCARDIA

  • HEART RATE: <60
  • RHYTHM: Regular
  • P WAVES: Normal
  • P-R INTERVAL: Normal
  • QRS WIDTH: Normal
  • INTERVENTIONS: Symptomatic? (low BP, pale, dizzy) – may need atropine; otherwise, monitor and check pulse

III. SINUS TACHYCARDIA

  • HEART RATE: >100
  • RHYTHM: Regular
  • P WAVES: Normal
  • P-R INTERVAL: Normal
  • QRS WIDTH: Normal
  • INTERVENTIONS: Determine causes (anxiety? pain?); may need beta blockers, calcium channel blockers, analgesics or antipyretics as appropriate

IV. SINUS ARRHYTHMIA

  • HEART RATE: Variable
  • RHYTHM: Irregular
  • P WAVES: Normal
  • P-R INTERVAL: Normal
  • QRS WIDTH: Normal
  • INTERVENTIONS: Continue to monitor, check pulse
Image Source: #1, #2.

Critical Care: Ventricular Rhythms, Asystole, PEA

I. PREMATURE VENTRICULAR CONTRACTIONS (PVCs)

  • HEART RATE: Variable
  • RHYTHM: Irregular
  • P WAVE: Normal
  • P-R INTERVAL: Normal
  • QRS WIDTH: Wide
  • INTERVENTIONS: Monitor; watch for sequences of PVCs which may lead to VTac

II. VENTRICULAR TACHYCARDIA (VTac)

  • HEART RATE: > 100
  • RHYTHM: Regular
  • P WAVES: None
  • P-R INTERVAL: None
  • QRS WIDTH: Wide
  • INTERVENTIONS: Check for pulse: if none, proceed to CPR & shock; otherwise, monitor; may need antidysrhythmics (Amiodarone, Procainamide)

III. VENTRICULAR FIBRILLATION (VFib)

  • HEART RATE: Variable, rapid
  • RHYTHM: Irregular
  • P WAVES: None
  • P-R INTERVAL: None
  • QRS WIDTH: Wild
  • INTERVENTIONS: EMERGENCY! Proceed to defibrillation, CPR & ACLS measures

IV. ASYSTOLE

  • NO heart rate; NO P waves, P-R intervals or QRS complexes
  • INTERVENTIONS: Check for causes*DO NOT shock!

V. PULSELESS ELECTRICAL ACTIVITY (PEA)

  • Any organized rhythm (other than VTac, VFib, asystole) with NO PULSE
  • INTERVENTIONS: First, CPR, intubation & ACLS measures; then look for causes
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Critical Care: Phases of Burn Care

PHASES OF CARE FOR THE BURN PATIENT:

  • Pre-hospital Phase
  • Emergent Phase
  • Acute Phase
  • Rehab Phase

I. PRE-HOSPITAL PHASE – primary concerns are ABC’s (airway, breathing, circulation)

  • Remove from the burn source
  • Check patency of airway and for adequate ventilation
  • Check for adequate circulation
  • Treat as needed – flush the skin for chemical injuries, remove clothing, 100% O2 for carbon monoxide poisoning
  • Prevent hypothermia – only cool for < 10 minutes

II. EMERGENT PHASE – main concerns are hypovolemic shock and edema

  • Airway management: may need intubation R/T edema or swelling of the airway, 100% humidified O2
  • Fluid resuscitation: 2 large bore IVs if 15% burn, central line if 30% burn
    Parkland (Baxter) Formula: 4 mL X kg X % Total Body Surface Area Burned (TBSAB)
    1/2 total in 1st 8 HRS
    1/4 total in 2nd 8 HRS
    1/4 total in 3rd 8 HRS
    Example: For a 70 kg patient with 50% TBSAB → 4 mL X 70 kg X 50 TBSAB = 14,000 mL in 24 hrs
    1/2 total in 1st 8 hrs = 7000 mL (875 mL/hr) ← to calculate, just divde 7000 mL/8 hrs
    1/4 total in 2nd 8 hrs = 3500 mL (437.5 mL/hr)
    1/4 total in 3rd 8 hrs = 3500 mL (437.5 mL/hr)
  • Wound care: debridement, escharatomies (an incision on the skin to relieve pressure due to edema), multiple dressing changes, room needs to be kept warm (85 degrees F), may need artificial skin
  • Pain management: analgesics, nonsystemic antimicrobial agents (Silverlon, Acticoat, Silvadene, Sulfamylon), thromboembolism prophylaxis (Lovenox), tetanus immunization
  • Nutrition: assess gastric residuals frequently, bowel sounds q8h, feedings usually started slowly at 20-40 mL/hr; may give calcium-containing supplements and milkshakes; supplemental vitamins in the emergent phase, iron in the acute phase

III. ACUTE PHASE

  • Wound care: debridement, topical antimicrobial creams (silver sulfadiazine, silver-impregnated dressings)
  • Excision and grafting: after 1-2 days, wound exicsion performed – important to maintain blood conservation and observe for circulation problems, coverage achieved with cultured epithelial autografts (grow skin from the patient’s own cells) or artificial skin
  • Pain management: 2 kinds of pain – background pain and treatment-induced pain, will need continuous IV opioids, around-the-clock management and may be even anxiolytics to potentiate pain relief, patient-controlled analgesia may also be used
  • Physical therapy: maintain joint function and prevent contractures, best times to perform active/passive range-of-motion exercises are during and after wound cleansing; patient’s with neck burns should sleep without pillows or neck dangling off the bed to hyperextend the neck

IV. REHAB PHASE

  • Range of motion exercises
  • Pressure bandages: used to keep scars flat, never worn over unhealed wounds
  • Relieve itching
  • Psychological support: patient may have permanent disfigurement due to scarring, assess for coping skills and family support
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Content derived from Medical-Surgical Nursing: Assessment and Management of Clinical Problems, 8th Edition.

Critical Care: Hemodynamics

HEMODYNAMIC MONITORING: BASIC SETUP
Hemodynamic monitoring measures the oxygenation, flow and pressure of the cardiovascular system. Data obtained helps to assess trends over time concerning the patient’s fluid volume, response to cardiovascular medications and improvement of therapy.

PRINCIPLES
Referencing
 is the positioning of the pressure transducer so that it is at the level of the heart
Phlebostatic Axis is the landmark for referencing of the pressure transducer at the 4th intercostal space, midchest

Zeroing is the confirmation of the pressure within the system; procedure: open stopcock to off TO the patient and observe the monitor for a reading of zero. Zeroing is typically performed at the beginning of the shift, when the validity of reading is questioned or after position changes.

HEMODYNAMIC PARAMETERS [THERAPEUTIC VALUES] 
Preload:
Central Venous Pressure (CVP) or Right Atrial Pressure (RAP) [2-8 mmHg] 
Pulmonary Artery Wedge Pressure (PAWP) or Left Atrial Pressure (LAP) [6-12 mmHg]
Pulmonary Artery Pressure (PAP) [4-12/25 mmHg] 

Afterload:
Systemic Vascular Resistance (SVR) [800-1200 dynes]
Pulmonary Vascular Resistance (PVR) [<250 dynes]

Other:
Stroke Volume (SV) [60-150 mL/beat]
Cardiac Output (CO) [4-8 L/min]
Cardiac Index (CI) [2.2-4 L/min/m2]

Arterial Hemoglobin Oxygen Saturation [95-100%]
Venous Hemoglobin Oxygen Saturation [70%]

 

Image Sources: #1, #2.
Content derived from Medical-Surgical Nursing: Assessment and Management of Clinical Problems, 8th Edition

Critical Care: Basics of EKGs

Interpretation:

  • 1 small square = 0.04 seconds horizontally and 0.1 mV vertically
  • 1 large square =  0.20 seconds horizontally and 0.5 mV vertically

To calculate heart rate (HR), there are 3 methods:

  • Count the number of R waves in a 6 second strip (30 large squares)
  • Count the number of large squares between two QRS complexes and divide into 300.
  • Count the number of small squares between two QRS complexes and divide into 1500

The process of interpreting a rhythm:

  1. Look for the P wave – is it upright or inverted? is there one for every QRS? are there flutter of fibrillatory waves present?
  2. Measure the PR interval – is it normal or prolonged?
  3. Measure duration of QRS complex – is it normal of prolonged?
  4. Assess the ST segment – is it flat, elevated or depressed?
  5. Note the T wave – is it upright or inverted?

Overall, you want to know: what is the dominant rhythm, what is the clinical significance and what is the appropriate treatment?

Normal EKG durations:

  • P wave = 0.06-0.12 seconds
  • P-R Interval = 0.12-0.20 seconds
  • QRS complex = 0.06-0.10 seconds
  • ST segment = 0.12 seconds
  • T wave = 0.16 seconds
  • QT interval = 0.34-0.43 seconds

Types of dysrhythmias (general names and classifications, more detail covered in your theory classes)

  • Sinus rhythms:
    Normal sinus rhythm
    Sinus tachycardia
    Sinus bradycardia
    Sinus arrhythmia
  • Atrial rhythms:
    Premature atrial contractions (PACs)
    Paroxysmal supraventricular tachycardia (P/SVT)
    Atrial flutter
    Atrial fibrillation
  • Heart blocks (the AV node is sick!):
    1st degree heart block
    2nd degree heart block, Type I (Wenckebach)
    2nd degree heart block, Type II
    3rd degree heart block or complete heart block
  • Ventricular rhythms:
    Premature ventricular contractions (PVCs)
    Ventricular tachycardia
    Ventricular fibrillation
    Asystole
    Pulseless electrical activity (PEA)

In studying for each of the dysrhythmias, you need to not only learn how to identify them, but also what to do next once you have identified the rhythm (treatment? monitor? IV? O2?)

Image Source: #1, #2.