ICU Protocols: A Step-wise Approach, Vol I

By Rajesh Chawla

The second edition of this highly successful book includes up-to-date notes on the step-wise management of clinical emergencies encountered in everyday intensive care units (ICU). Each thoroughly revised chapter provides concise information for point-of-care treatment, making it a practical guide clinicians can refer to on a daily basis at work or while traveling, or just to expand their knowledge. 

Volume 1 of ICU Protocols covers topics in pulmonology, cardiology, neurology, gastroenterology, nephrology and infectious diseases. The endocrine and metobolic systems, oncology, trauma, toxicology, envenomation and thermodysregulation, obstetrics, and perioperative care are covered in the second volume of ICU Protocols. 

This two-volume book is a must-read for intensivists, critical care specialists, junior trainees and residents working in ICUs. It is also relevant as course material for workshops on critical care, and essential for all hospital-based libraries. 

 “This book provides junior trainees with an introduction to the management of problems common to the critical care unit.” David J Dries, Doody’s Book Reviews, March, 2013, for the first edition of ICU Protocols. 

• Language: English
• Publisher: Springer
• Release date: Dec 31, 2019
• ISBN: 9789811508981

Book preview

Part IRespiratory System

© Springer Nature Singapore Pte Ltd. 2020

R. Chawla, S. Todi (eds.)ICU Protocolshttps://doi.org/10.1007/978-981-15-0898-1_1

1. Airway Management

Sheila Nainan Myatra¹  , Nirmalyo Lodh¹   and Jigeeshu V. Divatia¹  

(1)

Department of Anaesthesia, Critical Care and Pain, Tata Memorial Hospital, Mumbai, India

Sheila Nainan Myatra (Corresponding author)

Nirmalyo Lodh

Jigeeshu V. Divatia

A 60-year-old morbidly obese diabetic male patient with a left lobar pneumonia was shifted from the ward to the intensive care unit (ICU). He had history of progressive breathlessness and altered mental status for 6 h. He was drowsy but arousable, and had a respiratory rate of 33 breaths/min. SpO2 was 92% with facemask using 6 L of oxygen per min. Heart rate was 110/min and blood pressure was 90/60 mmHg.

Tracheal intubation is one of the most commonly performed procedures in the ICU. In the ICU, unlike in the operating room with controlled conditions, a significant proportion of these procedures can be associated with life-threatening complications. This chapter gives a stepwise approach to airway management in the ICU, along with a detailed description of the preparation, assessment, procedure, precautions, maintenance, and complications associated with tracheal intubation.

Step 1: Be Prepared for Airway Management Before Patient Arrival

History from the treating team will tell you about the condition of the patient and give you some idea of the equipment and expertise needed for airway management (e.g., mental state, respiratory and hemodynamic status, time of last meal, comorbidities that might complicate airway management etc.)

Check oxygen source, availability of a properly working suction, airway tray/cart, monitors, drugs, and personal protection equipment are kept ready.

Step 2: History and Initial Stabilisation

The incidence of complications during intubation in critically ill patients in the ICU ranges from 22% to 54%, significantly higher than the operating room, making tracheal intubation in ICU a high risk procedure.

Provide oxygen therapy on arrival to ICU while evaluating the patient. Attach the cardiac monitor, noninvasive blood pressure, and pulse oximeter and secure an intravenous line.

A quick history and assessment of the airway, breathing and circulation is required. History should include that related to the present illness, presence of co-morbidities, fasting status, contraindications to use succinylcholine/other drugs and previous history of a difficult intubation.

Critically ill patients, requiring airway support often present with hypotension and may be hypovolemic. The induction of general anaesthesia for intubation increases the intra-thoracic pressure during positive pressure ventilation, which may further worsen the hemodynamics especially in a hypovolemic patient, leading to precipitous fall in blood pressure, arrhythmias and sometimes cardiac arrest. Keeping this in mind, it is important to provide adequate volume support and keep vasopressor agents ready for use prior to tracheal intubation.

Step 3: Assess the Need for Tracheal Intubation

Look for clinical signs of acute respiratory failure: anxiousness, sweating, restlessness, cyanosis, shortness of breath, rapid breathing, air hunger, use of accessory muscles of ventilation, paradoxical abdominal breathing, exhaustion, confused state or drowsiness. The respiratory system examination findings are important

Lung ultrasound facilitates fast and accurate bedside examinations of most of the acute respiratory disorders.

The oxygen saturation by pulse-oximetry, an arterial blood gas analysis and a chest X-ray/CT scan if performed, can help assess the disease severity. However, this should not replace clinical evaluation or delay an airway intervention.

Common indications for endotracheal intubation are as follows:

Facilitation of invasive mechanical ventilation (inadequate oxygenation/ventilation, shock, cardiac arrest, avoidance of hypercarbia, controlled hyperventilation, need for neuromuscular paralysis, postoperative elective ventilation)

Protection of the respiratory tract from aspiration of gastric contents

Tracheobronchial toilet

Relief of upper airway obstruction

Step 4: Assessment for a Difficult Intubation

Several methods and tests are available; however, they are often impractical to use and also difficult to assess in the ICU unlike in the operating room, especially during emergency airway management.

Generally accepted, independent predictors of difficult airway in controlled setting which can be quickly and easily assessed are as follows:

Length of upper incisor—relatively long

Interincisor distance—less than two fingers (3 cm)

Overbite—maxillary incisors override mandibular incisors

Temporomandibular joint translation—cannot place mandibular incisors anterior to maxillary incisors

Mandibular space compliance—small, stiff, indurated, or occupied by mass

Thyromental distance—less than three fingers (6 cm)

Mallampati class—III and IV (Table 1.1 and Fig. 1.1)

Neck—short, thick

Limited neck mobility—cannot touch chin to chest or cannot extend neck

MACOCHA Score: This is a simple score developed for ICU patients which has been shown to differentiate between a difficult from a non difficult airway in ICU patients. The MACOCHA score has seven easily identifiable variables which are clinically relevant, it takes into account not only the anatomical difficulty (using the variable commonly tested in the operating room), but in addition physiological derangements like hypoxia and coma and also factors the skill of the airway operator. This makes it very relevant for use in ICU (Table 1.2)

A history of difficult intubation is the most reliable predictor of future difficult intubation.

Call for help in advance if difficulty in oxygenation, ventilation or intubation is anticipated.

Table 1.1

Mallampati classificationa (modified by Samsoon and Young)

aBy S. Rao Mallampati

../images/301581_2_En_1_Chapter/301581_2_En_1_Fig1_HTML.jpg

Fig. 1.1

Mallampati classification (modified by Samsoon and Young)

Table 1.2

MACOCHA score

Score from 0 to 12: 0 = easy; 12 = very difficult

Mallampati classification is based on the structures seen with maximal mouth opening and tongue protrusion without phonation in the sitting position. The observer’s eye should be at the level of the patient’s mouth. This classification correlates with intubation difficulty.

Step 5: Use a Checklist Before Tracheal Intubation

Providing adequate oxygenation is a priority over intubation. Hence, do not attempt intubation until everything is ready.

It is preferable to use an intubation checklist before intubation in the ICU. The checklist may be modified according to the needs of the ICU

The pre-intubation check list should include the following basic checks.

Patient preparation: Fasting status, drug allergies, contraindication to use succinylcholine and other drugs, intravenous access, fluid loading, patient optimization, preoxygenation and proper patient position,

Equipment check: Apply monitors (cardiac monitor, noninvasive blood pressure, pulse oximeter. Intra-arterial pressure monitoring is preferable and may be considered prior to nonemergency intubations especially in patients with shock) check all airway equipment (Table 1.3), including oxygen supply mechanical ventilator and circuit and a good working suction, check that all required drugs are drawn and kept ready (Table 1.4)

Team preparation: Allocate roles and responsibilities to the team members. A plan for who to call for help and who will note the time should be made, Check that personal protective equipment is being used

Preparation for airway difficulty: Discuss the airway plan, further plan in case of failed intubation and address any concerns the team members may have before proceeding for tracheal intubation

Table 1.3

Intubation tray/portable intubation cart—basic equipment

Table 1.4

Drugs used to facilitate intubation

Step 6: Patient Positioning for Tracheal Intubation

The Ramp position (alignment of the external auditory meatus and sternum Fig. 1.2) or the head elevated laryngoscopy position (HELP), a 25-degree head-elevation or back-up position is recommended over the classic sniffing position for tracheal intubation in ICU. This position is more comfortable for a patient to breathe. In the supine position, the posterior portions of the lung become more prone to collapse and atelectasis, thus reducing the oxygen reserves and shortening the safe apnoea time.

In patients with suspected cervical spine injury, maintain the head in neutral position and give manual in-line cervical stabilization. Use the cervical collar at all times during airway manipulations.

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Fig. 1.2

Ramp position: external auditory meatus and sternum should be in same alignment

Step 7: Preoxygenation and Apnoic Oxygenation

Remember, failure to intubate will not harm a patient but failure to oxygenate will. Ensure adequate oxygenation at all times.

Optimal pre-oxygenation increases the non-hypoxic apnoea time and provides a safety margin before desaturation occurs. Thus preoxygenation for at least 3 min is recommended to prolong the safe apnoea time before intubation.

Critically ill patients may have oxygen transport limitation and time-consuming airway management. During apnea, the time for oxyhemoglobin desaturation below 85% is much faster in these patients.

Though preoxygenation may not be feasible at all times, especially during an emergency tracheal intubation, every attempt should be made to preoxygenate the patient if time permits. In addition, it is important to remember that the response to preoxygenation may not always be good in critically ill patients, especially in those with respiratory conditions as compared to patients with normal lung function.

Pre-oxygenation with 100% oxygen prior to tracheal intubation can be done by one of the following methods:

Bag valve mask device with a reservoir bag (minimum 12–15 L/min of oxygen)

High flow nasal cannula oxygen (HFNCO)

Non invasive ventilation (NIV)

Use of NIVfor preoxygenation has been presently shown to be superior in case of acute respiratory failure, compared to other methods of preoxygenation in ICU. The NIV settings recommended for preoxygenation are: Pressure support ventilation with FiO2 of 1.0, inspiratory pressure support from 5 to 15 cm H2O, to obtain an expiratory tidal volume between 6 and 8 mL/kg and positive end-expiratory pressure of 5 cm H2O.

Apnoic oxygenation (oxygen delivery during the apnoea time). Providing nasal oxygen during intubation can help further prolong the safe apnoea time. Hence whenever feasible apnoic oxygenation should be provided. This can be provided using a nasal cannula with high flow oxygen. Two methods are available

Using High Flow Nasal Canula Oxygen (HFNCO). This is a special device which provides up to 60 L/min of heated humidified oxygen (100%). This can be used for preoxygenation first and then continued during apnoea until tracheal intubation. This requires dedicated equipment with oxygen humidification unit, nasal cannula and tubing connecting standard oxygen regulator to the transnasal oxygen cannula. This technique provides CPAP during pre-oxygenation and apnoeic oxygenation with gas exchange by flow-dependent flushing of the dead space. This method significantly prolongs the safe apnoea time, thus allowing securing a definitive airway during a difficult intubation or failed intubation to be done in an unhurried manner. HFNCO should be used when available, especially when a difficult airway is anticipated.

Alternatively, a simple nasal cannula may be used to deliver 15 L/min of oxygen during apnea when attempts at tracheal intubation are performed. This technique is called NO DESAT (Nasal Oxygen During Efforts at Securing A Tube). It is not as effective as HFNCO in ICU.

Step 8: Proceed with Tracheal Intubation

Check that personal protection gear used is adequate (gloves, mask, and eye protection) and expert help is available in case of an anticipated difficult airway.

Ensure that there is adequate monitoring with the cardiac monitor, noninvasive blood pressure, and pulse oximeter

Secure an intravenous line and give volume support

If the patient is to be ventilated, set up the ventilator and prepare drugs for long-term sedation.

Awake or asleep tracheal intubation can be performed. Awake intubation is the gold standard for an anticipated difficult intubation using a flexible bronchoscope (FOB) or video laryngoscope (VL). However, this may not be feasible in most ICU patients as they may be uncooperative due to their critical illness and administration of local anesthetic agents to facilitate the procedure may also be difficult. Asleep intubation can be performed after administering general anaesthesia using a direct laryngoscope (DL) or a vidolaryngoscope (VL). The use of VL improves glottic visualization as compared to DL, making it an important tool for difficult airway management in ICU, especially in expert hands.

Drug therapy(preintubation): The choice of agents (Table 1.4) will depend on the hemodynamic status of the patient and the anticipated nature of difficulty in intubation.

Patients may be given intravenous fentanyl, morphine, or midazolam. Physicians with appropriate experience may choose to use anesthetic induction agents such as ketamine, thiopentone sodium, propofol, or etomidate. These drugs should be given slowly to effect with or without muscle relaxants.

Intravenous ketamine, unless contraindicated, is the preferred induction agent, especially in hemodynamically unstable patients.

Etomidate is a cardiostable agent, but there are concerns of adrenal insufficiency following even a single dose.

Propofol can cause profound hypotension and myocardial depression and should be used with extreme caution.

Rapidly acting muscle relaxants such as succinylcholine/rocuronium may be used for rapid sequence intubation. Succinylcholine is used only in absence of hyperkalemia, severe acidosis, acute or chronic neuromuscular disease, extensive burn, and cervical trauma.

Longer-acting muscle relaxants (e.g., atracurium and vecuronium) should be given only after confirming that ventilation is possible.

Note that in sick, fatigued patients, very small drug doses may be sufficient. Inject drugs very slowly and until effect (do not give calculated/standard induction doses).

Clearupper airway obstructionif present:

Snoring, gurgling sound, paradoxical movement of the chest wall (inward movement during inspiration) and abdomen and inadequate/absent chest rise during ventilation may suggest upper airway obstruction.

Perform an oral or nasal (with soft malleable catheter) suctioning for no more than 10 s at a time and resume oxygenation soon after.

Use an oropharyngeal or nasopharyngeal airway if obstruction is not cleared by suctioning. The airway should have a length equivalent to distance from the tip of the nose/angle of the mouth to the tragus. Nasopharyngeal airway diameter should be less than the patient’s nostril. It should be avoided if the patient has risk of nasal trauma/bleeding or cerebrospinal fluid rhinorrhea.

Rapid sequence intubation (RSI): Most ICU patients are at a risk of aspiration. Critically ill patients may be not be fasted or have a slower gastric emptying (gastroparesis of critical illness, other medical conditions like diabetes etc.). Thus, conventionally, a rapid sequence induction (RSI), i.e. administration of rapid onset agents and avoidance of ventilation between induction and intubation, to limit gastric insufflation and aspiration is indicated. However, hypoxemia during this period is a concern these patients. The recent landmark PREVENT study showed that patients receiving gentle ventilation during RSI experienced lesser desaturation compared to controls, without suffering from an increased rate of pulmonary aspiration. Thus a modified RSI using gentle ventilation can be used to limit hypoxia during RSI.

After giving adequate preoxygenation and proper position, cricoid pressure (Sellick maneuver) is given just before the beginning of induction. As soon as the patient is asleep, increase the pressure.

Use only rapidly acting muscle relaxants (suxamethonium or rocuronium) while maintaining cricoid pressure.

Data from a large dataset suggests that the use of muscle relaxants in associated with fewer complications, including in patients with difficult airways.

Give gentle positive pressure ventilation (modified RSI) to maintain the oxygen saturation, especially in hypoxic patients.

Ensure adequate chest rise during mask ventilation. Hold the mask with both hands if ventilation is difficult.

Mask ventilation may be difficult in the following cases: BONES (B = beard, O = obese N = no teeth E = elderly (>55 years) or cathectic (sunken cheeks or edentulous) S = snores.

Apnoeic oxygenation using nasal oxygen (using oxygen flow of 15 L/min or HFNC) should be continued during attempts at intubation.

Perform laryngoscopy and intubation. Hold the laryngoscope handle in the left hand. Open the mouth of the patient with the thumb and the index finger of the right hand. Insert the laryngoscope blade gently into the mouth from the right-side angle of the mouth and move it to the left side taking the tongue along with the blade as it is inserted further inside the mouth. When the epiglottis is visualized, insert the curved blade into the vallecula and pull the laryngoscope forward and upward to expose the glottis (Fig. 1.3). Now, insert the ETT using the right hand between the vocal cords under direct vision.

For nasal intubation, use prior nasal mucosal vasoconstrictors and lubrication; Magill’s forceps may be used to guide the tube into the trachea.

Optimal external laryngeal manipulation (OELM) with the right hand or by an assistant by quickly pressing in both cephalad and posterior direction over the thyroid, cricoids or hyoid cartilage may be used to further optimize laryngoscopic view.

Use of stylet in ETT, bougie (a thin long plastic/rubber cylinder with a bent tip that is passed through the partially visible glottic opening and then the ETT is guided over it), or other airway adjunct can aid oral intubation.

After intubation, inflate the ETT cuff just enough (usually 4–6 mL) to avoid pharyngeal leak during ventilation.

Release cricoid pressure only after intubation, cuff inflation, and confirmation of tube placement.

Confirm tracheal tube placement (clinically by auscultation over the stomach and lungs (5-point auscultation): The gold standard to confirm correct tube placement is by using end-tidal CO2 with a portable capnograph (wait to see five to six consistent sine capnogram waveforms, without any decline before confirmation). Disposable calorimetric CO2 detectors devices may be used but are not as reliable. If still in doubt confirm by direct visualization of the ETT between cords using laryngoscopy or visualization of the trachea using bronchoscopy or simply take out the ETT and continue bag-mask ventilation.

Propertube positioning (ideally 2.5–4 cm above carina): Confirm bilaterally equal chest expansion and air entry in the lungs by auscultation. Using depth of tube insertion (i.e. tube fixation at 20 cm. mark for females and 22 cm. mark for males at the incisor level) is most superior method to determine proper tube position in adults. When all the above 3 methods are combined, the sensitivity is 100% and the specificity is 95%. Make a note of the exact distance of the ETT at the lips/nose on the case notes and ICU chart. This position should be noted daily during every nursing shift.

Tube fixation: Secure the ETT with two tube tapes and preferably also a tube tie or use a commercial ETT fixator. Insert an oro/nasogastric tube under direct vision.

Anticipate and treat hypotension with vasopressors and fluid therapy as appropriate.

../images/301581_2_En_1_Chapter/301581_2_En_1_Fig3_HTML.jpg

Fig. 1.3

Glottic view during laryngoscopy

Step 9: Intubation Care Bundle Management

The use of the following 10 elements of the intubation care bundle proposed by Jaber et al., has been shown to reduce severe life-threatening complications associated with tracheal intubation in ICU patients when performed collectively. The 10 components of the bundle are listed below.

Pre-Intubation

1.

Presence of two operators

2.

Fluid loading in absence of cardiogenic pulmonary oedema

3.

Preparation of long-term sedation

4.

Pre-oxygenation for 3 min with NIV in case of acute respiratory failure (FiO2 100%, pressure support ventilation level between 5 and 15 cm H2O to obtain an expiratory tidal volume between 6 and 8 mL/kg and PEEP of 5 cm H2O)

During Intubation

5.

Rapid sequence induction: Etomidate 0.2–0.3 mg/kg or ketamine 1.5–3 mg/kg combined with succinylcholine 1–1.5 mg/kg in absence of allergy, hyperkalaemia, severe acidosis, acute or chronic neuromuscular disease, burn patient for more than 48 h and spinal cord trauma

6.

Sellick maneuver

Post-Intubation

7.

Immediate confirmation of tube placement by capnography

8.

Norepinephrine if diastolic blood pressure remains low

9.

Initiate long-term sedation

Initial protective ventilation: Tidal volume 6–8 mL/kg of ideal body weight, PEEP 5 cm H2O and respiratory rate between 10 and 20/min, FiO2 100%, plateau pressure <30 cm H2O.

Step 10: Use of Guidelines for Tracheal Intubation in ICU

Recognizing the high risk of airway management in ICU, guidelines specific to tracheal intubation in ICU have been recently formulated by various international societies. These guidelines have subtle differences, however the broad principles are the similar with a focus on strategies to enhance safety during tracheal intubation.

The first guidelines on tracheal intubation in ICU was published by the All India Difficult Airway Association (AIDAA) in 2016 (Fig. 1.4). This guideline gives a stepwise approach to tracheal intubation in ICU using evidence based recommendations. These include the presence of two operators during intubation, hemodynamic optimization, preoxygenation, apnoiec oxygenation, use of a modified rapid sequence intubation with gentle ventilation to prevent hypoxia during intubation and limiting attempts at intubation to avoid life threatening complications.

These guidelines also provide a stepwise approach to the management of failed intubation being, continuation of mask ventilation, insertion of a supraglottic airway, one last attempt at mask ventilation if this fails and finally performing an emergency cricothyroidotomy to maintain the oxygenation while a tracheostomy is performed to establish a definite airway management. Unlike in the operating room, waking up the patient and postponing the surgery is not an option.

../images/301581_2_En_1_Chapter/301581_2_En_1_Fig4_HTML.jpg

Fig. 1.4

AIDAA guidelines for tracheal intubation in ICU

Step 11: Steps After Tracheal Intubation

Initiate mechanical ventilation if required.

Give analgesia and sedation as required.

Obtain chest radiograph to confirm tube position, bilateral lung expansion, and oro/nasogastric tube position.

Do not start feeding the patient until the position of oro/nasogastric tube is confirmed on chest radiograph.

Check the ETT cuff pressure using the cuff pressure machine and maintain it below 20 mmHg at all times.

Step 12: Watch for and Treat Immediate Complications of endotracheal intubation

Immediate complications

Esophageal intubation/endobronchial intubations/accidental ETT disconnections—atelectasis formation/collapse in the unventilated lung and hyperinflation and barotrauma with development of pneumothorax of the intubated lung (in endobronchial intubations) can cause profound hypoxemia manifesting as bradycardia and even progressing to cardiac arrest

Hypertension, tachycardia, raised intracranial pressure, and myocardial ischemia due to stimulation from laryngoscopy and intubation

Hypotension due to loss of sympathetic tone from drugs for intubation or dynamic hyperinflation due to hyperventilation or relative dehydration

Aspiration of gastric contents

Airway trauma, bleeding

Negative pressure pulmonary edema after sudden relief of severe airway obstruction

Cardiac arrest

Following an unanticipated difficult tracheal intubation, post procedure monitoring for complications is required. Watch for airway odema. Documentation of airway difficulty along with counseling of the patient/family is essential.

Step 13: Follow a Protocol for Airway Maintenance

Proper maintenance of the airway will reduce the incidence of accidental extubations, disconnections, tube blockage, and nosocomial pneumonia.

Keep the head elevated at 30–45°.

All ETT and tracheostomy tubes (TT) should be checked for position at incisor teeth/alae nasi, adequate fixation, patency, tracheal cuff pressure (<20 mmHg), and pharyngeal leak during each shift and should be documented.

In case of oral ETTs, secure firmly at the angle of the mouth and change position preferably every 24 h to avoid sores/ulcers.

Oral ETTs (without subglottic suction) should be cut 2–3 cm from the angle of the mouth.

The universal connector should be pushed right down to its shoulder to avoid accidental disconnections.

Confirm correct positioning of ETTs above the carina on the X-ray and document in the case notes.

All ventilated patients should receive humidification (with HME (Heat and Moisture Exchanger) filter or using a heated humidifier circuit).

ETT/TT suction should be done only when required and preferably using a closed suction system.

Sedate patients well when they need to remain intubated. Do not allow them to get restless.

Start weaning the patient off sedation, only in the daytime when ICU staff is in adequate strength.

Do not leave the patient unattended when sedation has been turned off and the patient is just about waking up. Reassure patients as they wake up from sedation.

Apply boxer gloves/restraints to those patients who appear agitated. Refrain from tying patient’s limbs.

Report any airway accident as a critical incident.

Step 14: Extubation of the Airway

Perform a good oral and endotracheal suction prior to extubation.

Keep all equipment ready for reintubation/noninvasive ventilation if required.

Do a cuff-leak test (especially after prolonged intubations)—deflate the ETT cuff and check for air leak around the cuff or tidal volume loss on the ventilator. If absent, suspect laryngeal edema. Consider the use of steroids and plan extubation at a later date over a tube exchanger.

Intravenous methylprednisolone started 12 h before a planned extubation has been shown to substantially reduce the incidence of postextubation laryngeal edema and reintubation in patients intubated for more than 36 h and having absent cuff leak.

In a patient with a difficult airway, ensure that expert airway help is available prior to extubation and extubate preferably over a tube exchanger FOB. Oxygenate the patient through the exchanger and remove it only when you are sure that the airway is not compromised/obstructed. If in doubt, pass the ETT back inside over the tube exchanger or FOB and secure in place.

Step 15: Continue to Watch for and Treat Complications of Tracheal Intubation (Days to Months After Extubation)

Sore throat

Airway edema

Airway infections/pneumonia

Laryngeal damage/granuloma

Tracheal stenosis, tracheomalacia, trachea-esophageal fistula

Suggested Reading

Casey JD, Janz DR, Russell DW, et al. Bag-mask ventilation during tracheal intubation of critically ill adults. N Engl J Med. 2019;380:811–21. https://​doi.​org/​10.​1056/​NEJMoa1812405. Critically ill adult patients receiving bag-mask ventilation had higher oxygen saturations and a lower incidence of severe hypoxemia, than those receiving no ventilation during tracheal intubation an increased risk of pulmonary aspirationCrossrefPubMedPubMedCentral

François B, Bellissant E, Gissot V, Desachy A, Normand S, Boulain T, Brenet O, Preux PM, Vignon P. Association des Réanimateurs du Centre-Ouest (ARCO). 12-h pretreatment with methylprednisolone versus placebo for prevention of postextubation laryngeal oedema: a randomised double-blind trial. Lancet. 2007;369(9567):1083–9. Methylprednisolone started 12 h before a planned extubation substantially reduced the incidence of postextubation laryngeal oedema and reintubation. Such pretreatment should be considered in adult patients before a planned extubation that follows a tracheal intubation of more than 36 hCrossref

Frat J-P, Ricard J-D, Quenot J-P, et al. Non-invasive ventilation versus high-flow nasal cannula oxygen therapy with apnoeic oxygenation for preoxygenation before intubation of patients with acute hypoxaemic respiratory failure: a randomised, multicentre, open-label trial. Lancet Respir Med. 2019;7:303–12. https://​doi.​org/​10.​1016/​S2213-2600(19)30048-7. Use of non-invasive ventilation or high-flow nasal cannula oxygen therapy with apnoeic oxygenation for preoxygenation before intubation. Severe hypoxaemia occurred less frequently after preoxygenation with non-invasive ventilation than with high-flow oxygenCrossrefPubMed

Higgs A, McGrath BA, Goddard C, et al. Guidelines for the management of tracheal intubation in critically ill adults. Br J Anaesth. 2018;120:323–52. https://​doi.​org/​10.​1016/​j.​bja.​2017.​10.​021. Guidelines for the management of tracheal intubation in critically ill adultsCrossrefPubMed

Jaber S, Jung B, Corne P, Sebbane M, Muller L, Chanques G, Verzilli D, Jonquet O, Eledjam JJ, Lefrant JY. An intervention to decrease complications related to endotracheal intubation in the intensive care unit: a prospective, multiple-center study. Intensive Care Med. 2010;36(2):248–55. The implementation of an intubation management protocol can reduce immediate severe life-threatening complications associated with intubation of ICU patientsCrossref

Kaufman D. Etomidate versus ketamine for sedation in acutely ill patients. Lancet. 2009;374(9697):1240–1. Ketamine is a safe and valuable alternative to etomidate for endotracheal intubation in critically ill patients and should be considered in those with sepsisCrossref

Myatra SN, Ahmed SM, Kundra P, et al. Republication: All India Difficult Airway Association 2016 Guidelines for Tracheal Intubation in the Intensive Care Unit. Indian J Crit Care Med. 2017;21:146–53. https://​doi.​org/​10.​4103/​ijccm.​IJCCM_​57_​17. Indian Guidelines for Tracheal Intubation in the Intensive Care UnitCrossrefPubMedPubMedCentral

Sitzwohl C, Langheinrich A, Schober A, Krafft P, Sessler DI, Herkner H, Gonano C, Weinstabl C, Kettner SC. Endobronchial intubation detected by insertion depth of endotracheal tube, bilateral auscultation, or observation of chest movements: randomised trial. BMJ. 2010;341:c5943. The highest sensitivity and specificity for ruling out endobronchial intubation, however, is achieved by combining tube depth, auscultation of the lungs, and observation of symmetrical chest movementsCrossref

© Springer Nature Singapore Pte Ltd. 2020

R. Chawla, S. Todi (eds.)ICU Protocolshttps://doi.org/10.1007/978-981-15-0898-1_2

2. Acute Respiratory Failure

Randeep Guleria¹  , Jaya Kumar¹   and Rajesh Chawla²  

(1)

Department of Pulmonary Medicine, All India Institute of Medical Sciences, New Delhi, India

(2)

Department of Respiratory, Critical Care & Sleep Medicine,Indraprastha Apollo Hospitals, New Delhi, India

Randeep Guleria (Corresponding author)

Jaya Kumar

Rajesh Chawla

Case scenario 1A 30-year-old male patient presented with acute onset of breathlessness, dry cough, fever, myalgia, and malaise for 4 days. On examination, he was found to be febrile and restless, with respiratory rate of 46/min and pulse rate of 124/min. His oxygen saturation was 80% on room air, and chest skiagram showed bilateral parenchymal infiltrate.Case scenario 2A 60-year-old male patient with chronic obstructive airway disease presented with increasing shortness of breath, cough, and expectoration for 5 days and drowsiness with confusion for 1 day. On examination, he was found to be drowsy, cyanosed with respiratory rate of 30/min, tachycardia, and flapping tremors. His oxygen saturation was 80% on initial evaluation, and a chest radiograph showed hyperinflated lung fields and right lower zone infiltrates.Case scenario 3A 30-year-old female patient with anxiety disorder presented to the emergency department in a comatosed condition with history of ingestion of some unknown tablets. On examination, she was found to be E2M4V1, with pulse rate of 64/min, respiratory rate of 14/min, and blood pressure of 90/60 mmHg.

Acute respiratory failure results from the failure of respiratory system in one or both of its gas exchange functions—oxygenation and carbon dioxide elimination. It is a major cause of morbidity and mortality in intensive care units (ICUs). There are two types—type 1 hypoxic respiratory failure and type 2 hypercapnic respiratory failure.

Step 1: Initiate Cardiopulmonary Resuscitation

All patients should be resuscitated as mentioned in Chap.Vol. 2.

Airway: In all patients with altered sensorium, a secure airway should be the first priority. This includes clearing the upper airway and keeping it patent. If the patient cannot maintain an airway, endotracheal intubation should be performed to keep the airway patent.

Breathing: Once the airway is patent, the breathing has to be assessed. If it does not result in adequate gas exchange, oxygen supplementation and assisted ventilation may be required.

Circulation: An intravenous access should be established and intravenous fluids should be started.

Step 2: Clinical Assessment Including History and Detailed Physical Examination

Take appropriate history and do detailed examination to distinguish whether the etiology is pulmonary or extrapulmonary and to know whether it is type 1 or type 2 respiratory failure (Tables 2.1 and 2.2). Assess the severity and find out the underlying cause and/or precipitating cause. Specific focus should be on the following:

A detailed respiratory system and neurological assessment.

Look for clinical features of hypoxia and hypercapnia (Tables 2.1 and 2.2).

Signs of pulmonary hypertension and right ventricular failure: Engorged neck veins, Pedal edema, Enlarged tender liver.

Clinical features of drug overdose.

Chest wall deformity, obesity.

Table 2.1

Hypoxia-related clinical features

Table 2.2

Hypercapnia-related clinical features

Step 3: Check Pulse Oximetry and Do Arterial Blood Gas Analysis

Pulse oximetryand arterial blood gases are the mainstay of diagnosis and essential to decide on the therapeutic intervention.

Oximetry is a rapid technique to know if there is significant hypoxia, but it gives no clue about the presence or absence of hypercapnia. In patients on supplemental oxygen, deteriorating pulmonary function is difficult to ascertain by pulse oxymetry as oxygen saturation in the flat part of oxyhemoglobin dissociation curve may not decrease appreciably with substantial decrease in PaO2.

Arterial blood gas analysis is essential for both diagnostic and therapeutic decisions.

Type 1 respiratory failure is recognized by hypoxemia (PaO2 < 60 mmHg). With or without widening of alveolar-arterial oxygen gradient, PaCO2 is either low or normal.

Type 2 respiratory failure is diagnosed when a PaO2 of less than 60 mmHg is associated with a PaCO2 of more than 45 mmHg and respiratory acidosis.

This needs to be followed by an assessment of the pH and HCO3 to decide whether the type 2 respiratory failure is acute, acute on chronic, or chronic.

Type II acute respiratory failure presents with low pH, high PaCO2, and normal HCO3; acute on chronic presents with low pH, high PaCO2, and high HCO3; while chronic respiratory failure presents with normal pH along with raised PaCO2 and HCO3.

This should be followed by an assessment of alveolar-arterial oxygen gradient, which helps to narrow down the cause of respiratory failure (see Appendix B).

A-a gradient = PAO2 − PaO2

A-a gradient = [FiO2 × (Patm − PH2O) − (PaCO2/0.8)] − PaO2

Step 4: Differentiate Between Type 1 and Type 2 Respiratory Failures

Type 1 respiratory failure occurs when the gas exchange is inadequate at rest or during exercise, leading to hypoxemia, and PaO2 is less than 60 mmHg (Table 2.3).

Table 2.3

Causes of hypoxemic respiratory failure

Type 2 respiratory failure occurs as a result of alveolar hypoventilation, which can be due to a pulmonary or extrapulmonary cause. Chronic obstructive pulmonary disease is the commonest cause of type 2 respiratory failure, but various other conditions listed below can also lead to hypercapnia and respiratory failure (Table 2.4).

Table 2.4

Causes of type 2 respiratory failure

An approach to a patient with acute hypoxemic respiratory failure is summarized in Fig. 2.1.

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Fig. 2.1

An approach to hypoxemic respiratory failure to know the etiology

Step 5: Send Investigations

Complete hemogram and biochemistry

Lung function tests (if possible) that helps to differentiate between obstructive, restrictive, and mixed ventilatory defects

Chest radiograph that may help to identify hyperinflation, pulmonary edema, pneumonia, pneumothorax, neoplasm and others to give a clue to the underlying etiology

Electrocardiogram to identify cardiac disorders

Computed tomography (CT) or magnetic resonance imaging (MRI) if indicated for interstitial lung disease, neoplasm, stroke, and other neurological disorders

Two-dimensional echocardiography for identification of cor pulmonale, intracardiac shunt, patent ductus arteriosus, and pulmonary embolism

Step 6: Initiate Specific Treatment

The primary aim is to maintain oxygenation and adequate alveolar ventilation and treatment for the underlying etiology. The key principles in the management of respiratory failure are as follows:

Optimized oxygen therapy.

Identification of the underlying cause and adequate treatment for the same.

Clinical assessment and arterial blood gases to help decide the severity.

Treatment for any precipitating cause.

Appropriate pharmacological treatment e.g. Bronchodialators.

Ventilatory support—noninvasive and invasive.

Oxygen therapy (see Chap. 14, Vol. 1).

The primary goal is to correct the hypoxemia to maintain adequate tissue oxygenation.

Oxygen has to be given cautiously with monitoring as uncontrolled high-flow oxygen can lead to respiratory depression and worsening hypercapnia in type 2 respiratory failure. Oxygen saturation around 90% should be maintained.

Supplemental oxygen can be provided through nasal prongs at a flow rate of 1–3 L/min or through a Venturi mask to deliver 24–28% oxygen in hypercapnic failure.

Nasal prongs are better tolerated but provide less predictable oxygen concentration in comparison to the Venturi mask.

The aim is to maintain oxygen saturation above 90%, PaO2 more than 60 mmHg, and pH more than 7.35.

Assisted ventilation, either noninvasive or invasive, is indicated if there is clinical deterioration or if respiratory acidosis persists despite optimum oxygen and medical therapy. Refer to specific Chaps. 3 and 4, Vol. 1 for further details.

Step 7: Further Management

Optimum treatment for the underlying etiology must be undertaken simultaneously.

Suggested Reading

Baudouin S, Blumenthal S, Cooper B, et al. Role of non-invasive ventilation in management of acute respiratory failure in emergency department. Thorax. 2002;57:192–211. BTS standards of care committee—noninvasive ventilation in acute respiratory failureCrossref

Epstein SK. Acute respiratory failure. In: Bope ET, Kellerman R, Rakel RE, editors. Conn’s current therapy 2011, , Section 4. 1st ed. Philadelphia: Elsevier Saunders; 2011. p. 233–8. This chapter discusses causes and treatment strategies for acute respiratory failure.

Goldman L. Goldman’s Cecil medicine, Chapter 104. 24th ed. Philadelphia: Elsevier Saunders; 2011. p. 629–38. This chapter discusses the physiology and algorithmic approach for acute respiratory failure

Lellouche F. Non-invasive ventilation in patients with hypoxemic acute respiratory failure. Curr Opin Crit Care. 2007;13(1):12–9. This article discusses the role of noninvasive ventilation in management of acute respiratory failureCrossref

Yeow ME, Santanilla JI. Non-invasive positive pressure ventilation in the emergency department. Emerg Med Clin North Am. 2008;26:835–47.Crossref

© Springer Nature Singapore Pte Ltd. 2020

R. Chawla, S. Todi (eds.)ICU Protocolshttps://doi.org/10.1007/978-981-15-0898-1_3

3. Noninvasive Positive-Pressure Ventilation

Rajesh Chawla¹   and Subhash Todi²  

(1)

Department of Respiratory, Critical Care & Sleep Medicine, Indraprastha Apollo Hospitals, New Delhi, India

(2)

Department of Critical Care & Emergency Medicines, A.M.R.I. Hospital, Kolkata, India

Rajesh Chawla (Corresponding author)

Subhash Todi

A 56-year-old male patient, a known case of chronic obstructive pulmonary disease (COPD), presented with acute breathlessness, cough with increase in expectoration, and low-grade fever. On examination, he was found to be in acute respiratory distress, with respiratory rate (RR) of 28/min. He was using his accessory muscles, was slightly drowsy, and breath sounds were diminished on both sides.

Noninvasive positive-pressure ventilation (NIV) augments spontaneous ventilation using the tight-fitting nasal or oronasal mask without endotracheal intubation. This can be used in a large number of conditions if there is no contraindication. The application of NIV should not delay clinically indicated endotracheal intubation.

Step 1: Initial Resuscitation

The patient should be resuscitated as mentioned in Chap. Vol. 2.

The first step after resuscitation would be to quickly examine the patient in detail.

Look for hemodynamic instability, sensorium, and oxygenation by pulse oximetry.

If SpO2 is low, give oxygen—not more than 1–2 L/min. Titrate oxygen to minimum flow to keep SpO2 at 88–92%.

Check arterial blood gas (ABG) and initiate other investigations as mentioned below:

Hemogram, blood urea, serum creatinine, and serum electrolytes

Blood and sputum culture if infection is suspected

Chest skiagram

Electrocardiogram (ECG) and Echocardiogram (Echo)

Disease-specific treatment such as bronchodilators (salbutamol and ipratropium nebulization), antibiotics, corticosteroids should be started.

Step 2: Assess the Need of NIV

In addition to the rest of the medical treatment, NIV should be applied simultaneously to a patient in acute respiratory failure (ARF), based on the clinical criteria (Table 3.1), provided there is no contraindication.

There are no absolute contraindications for the use of NIV. Some contraindications have, however, been suggested (Table 3.2).

NIV is indicated in patients with appropriate diagnosis and proven evidence of effectiveness of NIV(Table 3.3) if clinical criteria are fulfilled (Table 3.1).NIV has been found to be most effective in COPD, Cardiogenic pulmonary oedema and weaning in COPD. NIV should be initiated in COPD when pH < 7.35 and pCO2 > 45 mmHg persist or develop despite optimal medical therapy. Severe acidosis is not a contraindication to NIV so long as the expertise to perform safe endotracheal intubation is readily available. The lower the pH the more chances of failure, one should not delay intubation when it is indicated.

Table 3.1

Clinical criteria

Table 3.2

Contraindications

Table 3.3

Effectiveness for NIV in ARF from different causes

A strong, B intermediate, C weak

Step 3: Application of NIV

Protocol for application of NIV : For successful NIV, it is important to fine-tune the patient, interface, and ventilator.

Patient interface: Many interfaces like nasal, oronasal mask, full face mask, nasal prongs (pillows) and Helmet can be used for the application of NIV.

Mode of ventilation: NIV can be applied using Portable pressure ventilators or Conventional ICU ventilators. NIV can be applied using the same modes that are used for invasive mechanical ventilation, however certain modes are used more frequently.

In portable pressure ventilators Bilevel positive airway pressure (BPAP)—spontaneous or spontaneous/timed mode are used for application of NIV.

Pressure support/pressure control/volume control modes are used more commonly when conventional ventilators are used for NIV application. Conventionally for the application of NIV in acute respiratory failure, pressure-targeted modes are the modes of choice.

Both pressure support (PS) and pressure control modes are effective. Pressure modes are preferred because there are many advantages of pressure targeted modes like pressure delivered is constant and pressure targeted ventilation compensates for air leak

During application of NIV through portable pressure ventilator in spontaneous mode, when patient initiates a breath, he gets pressure from the machine which is called Inspiratory Positive Airway Pressure (IPAP) which is applied all through inspiration. When the flow falls to a predetermined value set on the ventilator, patient gets a pressure which is applied all through expiration which is called Expiratory Positive Airway Pressure(EPAP). IPAP Improves ventilation and increases tidal volume. and helps in CO2 removal. EPAP improves oxygenation, opens up the Upper airway and neutralize auto PEEP. Pressure Support applied is the difference between IPAP and EPAP(PS = IPAP-EPAP).

Application of NIV Using Portable Pressure Ventilators

Explain the therapy and its benefit to the patient in detail. Also, discuss the possibility of intubation.

Choose the correct size interface. There are many types of interfaces like nasal mask, oronasal mask, total face mask and Helmet The oronasal mask is preferred in ARF.

Set the NIV portable pressure ventilator in spontaneous or spontaneous/timed mode.

Try to set machine parameters which are comfortable for the patient.

Always set the back up respiratory rate 2 to 3 less than patient respiratory rate.

Set I:E ratio 1:2 in COPD and 1:1 in OHS, NMD, CWD.

Rise Time is the time taken from EPAP to IPAP. In obstructive patients set Rise time 100 ms to 400 ms(1 to 4) and in restrictive disease patient, set rise time 300 ms to 600 ms (from 3 to 6).

Set max Inspiratory time 0.8 to 1.2 s (COPD) and 1.2 to 1.4 s in OHS,NMD,CWD.

Now Start titration with very low settings, low inspiratory positive airway pressure (IPAP) of 6–8 cm H2O with 2–4 cm H2O of expiratory positive airway pressure (EPAP). The difference between IPAP and EPAP should be at least 4 cm H2O at all times.

To start with administer oxygen at 2 L/min.

Hold the mask with the hand over the face. Do not fix it.

It is important to select proper size mask. Use the smallest possible mask. Increase EPAP by 1–2 cm increments until the patient’s inspiratory efforts are able to trigger the ventilator.

If the patient is making inspiratory effort and the ventilator does not respond, it indicates that the patient has not generated enough respiratory effort to counter auto-PEEP and trigger the ventilator (in COPD patients). Increase EPAP further until this happens. Most of the patients require EPAP of about 4–6 cm H2O. Patients who are obese or have obstructive sleep apnea require higher EPAP to trigger the ventilator.

When the patient’s effort is triggering the ventilator, leave EPAP at that level.

Now, start increasing IPAP in increments of 1–2 cm up to a maximum pressure, which the patient can tolerate without discomfort and there is no major mouth or air leak.

Now, secure interface with head straps. Avoid excessive tightness. If the patient has a nasogastric tube, put a seal connector in the dome of the mask to minimize air leakage.

After titrating the pressure, increase oxygen to bring oxygen saturation to around 88 to 92% in hypercapnic respiratory failure. Oxygen should be entrained as close to the patient as possible. Adjust regularly oxygen flow required to maintain Spo2 between 88 to 92%.

As the settings may be different in wakefulness and sleep, readjust them accordingly.

When NIV is being initiated for ARF, close monitoring and the capability to initiate endotracheal intubation and other resuscitation measures should be available in the same setup. Start NIV preferably in the intensive care unit or in the emergency room in ARF.

Humidification is not routinely required. Heated humidification can be used in cases of mucosal dryness or if respiratory secretions are thick and tenacious

If the patient is dependent on NIV, bronchodilator drugs can be given via a nebuliser inserted into the ventilator tubing.

Application of NIV Using a Critical Care Ventilator

There are several advantages of using NIV through standard ICU ventilator like one can give precise and also high concentration of oxygen. Separate inspiratory and expiratory tubing decrease the rebreathing of carbon dioxide. Large mask leaks and/or patient disconnections are appreciated quickly and it has better alarms and monitoring features.

The first step is to select a ventilator, which is capable of fulfilling the needs of the patient.

Explain the therapy to the patient.

Choose the NIV mode. Pressure support or pressure control modes are preferred. Standard critical care ventilators using flow-by system (noninvasive mode option) allow the patient to breathe without expending effort to open valves. In selected patients, such as those suffering from neuromuscular diseases, volume assist or volume control mode may be used.

Choose an appropriate interface.

Silent ventilator alarms.

Keep FiO2 at 0.5.

Using pressure support approach

Start with low settings such as inspiratory pressure support at 5–6 cm H2O and PEEP at 4 cm H2O.

Initiate NIV while holding the mask in place and confirm optimum fit. If it is big or small or loose, change it.

Hold the mask. Do not fix the headgear.

Now, increase PEEP until inspiratory efforts are able to trigger the ventilator.

If the patient is making inspiratory effort and the ventilator does not respond, it indicates that the patient has not generated enough respiratory effort to counter auto-PEEP and trigger the ventilator (in COPD patients). Increase PEEP further until this happens.

Once the patient’s inspiratory efforts trigger the ventilator, start increasing pressure support further,