Page 427 - ACCCN's Critical Care Nursing

404 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

and extubation readiness. 243-247 Recently, coupling of a difficulty. 260 These patients are most likely to benefit from
sedation and weaning protocol was found to result an individualised and structured approach to weaning
in a three-day reduction in the duration of ventilation using progressive lengthening of tracheostomy trials with
compared to standard care in four North American supportive ventilation in between in combination with
hospitals. 248 A recent systematic review and meta-analysis early physical therapy.
of 11 weaning protocol trials including 1971 patients
demonstrated a reduction in the duration of mechani-
cal ventilation. 249 However, the authors cautioned that
the effect of weaning protocols may vary according Practice tip
to the ICU organisational characteristics such as
an intensivist-led ICU model, high levels of physician Tachypnoea and decreased tidal volumes during weaning are
staffing, structured ward rounds, collaborative discus- clear indicators that a patient is not ready for extubation.
sion and more frequent medical review; all character-
istics reported for ICUs in Australia and New
Zealand. 250,251 Complications of Mechanical Ventilation
Physiological complications associated with mechanical
Automated weaning ventilation include ventilator-associated lung injury
Automated computerised systems potentially enable (VALI) and nosocomial infection (VAP). 116,122 VALI occurs
more efficient weaning by providing improved adapta- through alveolar over-distension and cyclic opening
tion of ventilatory support through continuous monitor- and closing of alveoli resulting in diffuse alveolar
ing and real-time intervention. 252 One such system, damage, increased permeability, pulmonary oedema,
SmartCare™/PS, monitors three respiratory parameters, cell contraction and cytokine production. 122,130,136,261-263
frequency, V T and end-tidal carbon dioxide (ETCO 2 ) con- VAP substantially increases the duration of ICU stay
centration, every two or five minutes and periodically and is associated with an attributable mortality of
adapts pressure support (PS). 252,253 SmartCare/PS estab- 5.8–8.5%. 264-266 Additional complications associated
lishes a respiratory status diagnosis, based on evaluation with mechanical ventilation are listed in Table 15.8.
of the three parameters, and may either decrease or Complications can occur due to inappropriate applica-
increase PS, or leave it unchanged to maintain the patient tion of mechanical ventilation. This may result in extra-
in a defined ‘respiratory zone of comfort’. 254,255 Once alveolar gas causing pneumothoraces or subcutaneous
SmartCare/PS has successfully minimised the level of PS, emphysema due to high peak inspiratory pressures, and
a one-hour observation period occurs. For patients who alveolar stretch and oedema formation as the result of
remain within the respiratory zone of comfort through- large tidal volumes. 68
out the observation period, SmartCare/PS recommends
to ‘consider separation’, indicating the patient’s respira- SUMMARY
tory status now suggests the patient will tolerate
extubation. Support of oxygenation and ventilation during critical
illness are key activities for nurses in ICU. Oxygen therapy
SmartCare/PS substantially reduced the duration of ven- promotes aerobic metabolism but has adverse effects that
tilation and ICU length of stay when compared to need to be considered. Various oxygen delivery devices
physician-controlled weaning using local guidelines in provide low or variable flows of oxygen.
five European ICUs. 256 These effects were not confirmed
when the SmartCare/PS system was compared to weaning Strong evidence supports the use of NIV for COPD and
managed by experienced critical care nurses in a single CHF, but caution is required when used for other
Australian setting. 257 diagnoses such as pneumonia. NIV success is dependent
on patient tolerance, with common complications
including pressure ulcers, conjunctival irritations, nasal
The difficult-to-wean patient congestion, insufflation of air into the stomach and
International reports indicate patients that require claustrophobia.
mechanical ventilation for ≥21 days account for less than
10% of all mechanically-ventilated patients, but occupy Airway support can be provided with oro- or nasopharyn-
40% of ICU bed days and accrue 50% of ICU costs. 258,259 geal airways, laryngeal mask airways and endotracheal
A recommendation from the National Association for intubation; oral intubation is the preferred method. For
Medical Direction of Respiratory Care (NAMDRC) states a patient with an ETT, the key points for practice are:
that prolonged mechanical ventilation should be defined ● ETT placement should be confirmed with end-tidal
as ‘≥21 consecutive days of ventilation required for ≥6 CO 2 monitoring
230
hours per day’. Prolonged weaning has been defined as ● the aim of endotracheal cuff management is to prevent
greater than 7 days of weaning after the first SBT or more airway contamination and enable positive pressure
230
than three SBTs. Little evidence defines the optimal ventilation
method for managing the difficult-to-wean patient. One ● closed suctioning reduces alveolar derecruitment
trial found no difference in weaning duration or success compared to opening suctioning
when comparing tracheostomy trials to low-level pressure ● instillation of normal saline is not recommended
support in patients with COPD experiencing weaning during routine tracheal suctioning.