Spontaneous ventilation

This graph can be used to explain a number of different aspects of compliance. The axes as shown are for spontaneous ventilation as the pressure is negative. The curve for compliance during mechanical ventilation looks the same but the x axis should be labelled with positive pressures. The largest curve should be drawn first to represent a vital capacity breath. 

PAOP This must be lower than the PA diastolic pressure to ensure forward flow. It is drawn as an undulating waveform similar to the CVP trace. The normal value is 6-12 mmHg. The values vary with the respiratory cycle and are read at the end of expiration. In spontaneously ventilating patients, this will be the highest reading and in mechanically ventilated patients, it will be the lowest. The PAOP is found at an insertion length of around 45 cm. 

Fig. 15. Relationship between the alfentanil plasma concentrations and the probability of needing naloxone to restore adequate spontaneous ventilation. The diagram at the upper part shows the alfentanil plasma concentrations of the patients who required naloxone (upward deflection) or did not require naloxone (downward deflection). The plasma concentration-effect curve for this clinical endpoint (lower part) was defined from the quantal data shown in the upper diagram using logistic regression. Bars indicate SE of C5o%. (From Ausems ME, Hug CC, Stanski DR, Burm AGE. Plasma concentrations of alfentanil required to supplement nitrous oxide anaesthesia for general surgery. Anaesthesiology 1986 65 362-73, reproduced by permission.)...

Halothane (Fluothane) depresses respiratory function, leading to decreased tidal volume and an increased rate of ventilation. Since the increased rate does not adequately compensate for the decrease in tidal volume, minute ventilation will be reduced plasma PaCOz rises, and hypoxic drive is depressed. With surgical anesthesia, spontaneous ventilation is inadequate, and the patient s ventilation must be controlled. 

In critically ill patients who have ventilatory failure from various causes (eg, severe bronchospasm, pneumonia, chronic obstructive airway disease), it may be necessary to control ventilation to provide adequate gas exchange and to prevent atelectasis. In the ICU, neuromuscular blocking drugs are frequently administered to reduce chest wall resistance (ie, improve thoracic compliance) and ineffective spontaneous ventilation in intubated patients. 

After collecting the last sample (90 min after intrathecal administration of test substance) the catheters were removed, and all incisions were sutured. Isoflu-rane was discontinued, and the lungs were ventilated with 100% oxygen. Extubation of the trachea was performed when adequate spontaneous ventilation occurred. The animals were allowed to recover with infusion of Ringer s solution and antibiotic treatment. 

Beloeil H, Corsia G, Coriat P, Riou B. Remifentanil compared with sufentanil during extra-corporeal shock wave lithotripsy with spontaneous ventilation a double-blind, randomized study. Br J Anaesth 2002 89(4) 567-70. 

A healthy 22-year-old woman at 41 weeks gestation presented for urgent cesarean section following fetal heart rate deceleration (20). She was given sufentanil 10 micrograms plus 0.1% bupivacaine 10 mg intrathe-cally and 8 minutes later became unrousable and apneic. After 3 minutes spontaneous ventilation resumed. 

A mother with eclampsia was unsuccessfully treated with diazepam, total dose 120 mg, and phenytoin 750 mg she received thiopental and had an emergency cesarean section at 33 weeks gestation (12). The infant was unresponsive and floppy, requiring intubation and ventilation. At 10 hours after delivery a flumazenU infusion was begun the baby responded with facial and limb movements within 30 seconds, resumed spontaneous ventilation, and was extubated 4 hours later. She was maintained on a slowly reducing flumazenil infusion over the next 4 days while the benzodiazepines were metabolized. 

Tojitna, H., Kubin, L, Kimura, H, and Davies, R. 0. (1992), Spontaneous ventilation and respiratory motor output during carbachol-induccd atonia of REM sleep in the decerebrate cat. Sleep 15,404—414. 

Hydromorphone. Early respiratory depression has been reported when droperidol was given 10 minutes before epidural hydromorphone 1.25 mg the patient beeame apnoeic 15 minutes after the epidural was given. Naloxone did not reverse the respiratory depression, but spontaneous ventilation resumed within 3 minutes of a 1-mg intravenous dose of physostigmine. ... 

Mandatory Ventilation Adaptive Pressure Control Adaptive Support Ventilation Spontaneous Ventilation Continuous... 

As in the case of mandatory ventilation, several modes of spontaneous ventilation have been devised by therapists. Two of the most important and popular spontaneous breath delivery modes are described below. 

Continuous positive airway pressure (CPAP) A spontaneous ventilation mode in which the ventilator maintains a constant positive pressure, near or below PEEP level, in the patient s airway while the patient breathes at will. 

Synchronous intermittent mandatory ventilation (SIMV)—this mode permits the patient to breathe on their own (spontaneous ventilation), but supplements the volume that the patient breathes according to a set breathing rate. For example, the SIMV rate may be set to 4 breaths per minute while the patient is breathing low volumes at a rate of 20 breaths/min. Every 12 s, the ventilator will assist a patient-triggered breath and deliver an adequate tidal volume. If the patient stops breathing, then the ventilator will deliver a set volume of gas 4 times/min. 

Nitrous oxide/oxygen (70% 30%). Spontaneous ventilation. Rats sedated but conscious (Sakurada et al. cited in Ingvar et al., 1980.)... 

Relative not recommended for use in spontaneous ventilation anesthesia not recommended as an analgesic in the immediate post-operative period except in ventilated patients. 

Shen X, Hu CB, Ye M, Chen YZ. Propofol-remifentanil intravenous anesthesia and spontaneous ventilation for airway foreign body removal in children with preoperative respiratory impairment. Paediatr Anaesth 2012 22 1166-70. 

Respiratory rehabilitation including facilitation of bronchial drainage, progressive weaning from controlled ventilation, and switching to assisted or spontaneous ventilation... 

The patients who required a tracheostomy may subsequently manage spontaneous ventilation with improvements in their underlying condition and respiratory muscle strength and endurance. Resolution of dynamic hyperinflation also improves the length-tension relationships of the inspiratory muscles (56). Strengthening of the upper extremities or the inspiratory muscles has provided mixed results (57,58). 

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