Initiation and Modification of Therapeutic Interventions
From order to titration
Every intervention item yields to the same sequence: confirm the indication, select the device, set the parameter, set alarm limits that bracket the goal, reassess, then document. Know your targets: SpO2 94–98% for most adults and 88–92% for patients at risk of hypercapnic respiratory failure.
Devices and settings
Low-flow oxygen (nasal cannula, simple mask) delivers a variable, estimated FiO2; air-entrainment and high-flow devices (Venturi mask, high-flow nasal cannula) deliver a set FiO2 and, with HFNC, flow-dependent dead-space washout plus low-level positive pressure. For lung expansion, understand incentive spirometry targets, IPPB indications, and CPAP/PEP pressures. For bronchial hygiene, match the technique to the problem: secretion mobilization (modified postural drainage, oscillating PEP, high-frequency chest wall oscillation) versus secretion clearance (cough augmentation, suctioning, mechanical insufflation-exsufflation).
Mechanical ventilation
Initial settings should be reasoned, not memorized: mode, tidal volume 6–8 mL/kg predicted body weight (6 mL/kg in ARDS), rate to match needed minute ventilation, PEEP, and FiO2 titrated down as tolerated. Set alarms within about 10–20% of delivered values. Weaning combines daily spontaneous breathing trials with readiness measures: RSBI below about 105, NIF more negative than –20 to –25 cm H2O, and vital capacity above 10–15 mL/kg.
Traps
Do not chase saturation with FiO2 alone once it is already high - look for the cause and consider PEEP. Do not read a rising EtCO2 as improvement when it reflects hypoventilation. Beware "increase FiO2" as the answer when the real problem is a mucus plug or a worsening shunt.
Worked rule
RSBI = respiratory rate divided by tidal volume in liters. Rate 30 with VT 300 mL (0.3 L) gives 100, below 105: a favorable weaning sign, but only if the rest of the readiness picture fits.