Positive pressure ventilation

Lung Stretch and Ventilator-Induced Lung Injury 

PPMV can also affect cardiovascular function (20,51,52) by decreasing right ventricular filling, cardiac output, and pulmonary perfusion. This complication is the rationale for using volume repletion to maintain cardiac output in the setting of high intrathoracic 

Dyspnea, anxiety, and discomfort from inadequate ventilatory support can lead to stress-related catechol release with subsequent increases in myocardial oxygen demands and dysrhythmias (54). Coronary blood vessel oxygen delivery can also be compromised by inadequate gas exchange from the lung injury coupled with low mixed venous P02 due to high oxygen consumption of the ventilatory muscles. 

Oxygen concentrations approaching 100% cause oxidant injuries in airways and lung parenchyma (55). However, the safe oxygen concentration or duration of exposure is unclear, with a consensus that a fraction of inspired oxygen (F102) 0.4 is safe and an F102 0.8 should be avoided (13). 

During interactive modes, insufficient unloading from either inadequate support levels or from dys-synchronous flow can produce or perpetuate muscle dysfunction, from imposed loading (35-38). Mechanical ventilation can also produce muscle dysfunction if only controlled ventilation is used for prolonged periods. This ventilator-induced diaphragmatic dysfunction is akin to muscle atrophy in other skeletal muscles (33,34). 

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FPN No. 1) In some cases, hazards may be reduced or hazardous (classified) locations limited or eliminated by adequate positive-pressure ventilation from a source of clean air in conjunction with effective safeguards against ventilation failure. 

Discharge from the intensive care unit requires maintenance of the preceding parameters in the absence of ongoing IV infusion therapy, mechanical circulatory support, or positive-pressure ventilation. 

Noninvasive positive-pressure ventilation (NPPV) provides ventilatory support with oxygen and pressurized airflow using a face or nasal mask with a tight seal but without endotracheal intubation. In patients with acute respiratory failure due to COPD exacerbations, NPPV was associated with lower mortality, lower intubation rates, shorter hospital stays, and greater improvements in serum pH in 1 hour compared with usual care. Use of NPPV reduces the complications that often arise with invasive mechanical ventilation. NPPV is not appropriate for patients with altered mental status, severe acidosis, respiratory arrest, or cardiovascular instability. 

Apply Positive Pressure Ventilation using PEEP at 4 cm/water or CPAP mask. 

Anesthetic techniques that have minimized adverse effects include the use of muscle relaxants and, more recently, nerve stimulators to assess adequacy of relaxation, the introduction of very rapid acting, short-duration barbiturates, and the use of atropinic agents to minimize the cardiovascular response to a combination of a seizure and anesthesia (93). In addition, 100% oxygenation (adequacy monitored by a pulse oximeter) with positive-pressure ventilation can minimize related cardiac events and memory disruption. 

Rarely, prolonged apnea may occur in those susceptible because of an inability to adequately metabolize succinylcholine (i.e., increased pseudocholinesterase levels). This condition requires continued positive-pressure ventilation until the patient begins spontaneous respiration. 

Pieters T, Amy JJ, Burrini D, Aubert G, Rodenstein DO, Collard Ph. Normal pregnancy in primary alveolar hypoventilation treated with nocturnal nasal intermittent positive pressure ventilation. Eur Respir J 1995 8 1424—1427. 

Figure 2. Respiratory protective equipment. One-piece positive pressure ventilated suits. Mine Safety Appliances Company...

Intubation and positive pressure ventilation may complicate pneumothoracies and tension pnuemothoracies. 

How should hospitals increase their capacity to provide mechanical ventilation for a surge of patients with acute respiratory failure during a mass casualty event or influenza pandemic Rubinson and colleagues address this issue in a recently published article (Rubinson, Branson, Pesik, Talmor, 2006). Their report is based on an evaluation and assessment of a wide range of positive pressure ventilation (PPV) equipment, with the goal of determining the suitability of each device for mass casualty care. The article provides information useful for determining which types of PPV equipment would be the best choice for hospitals in need of a serviceable alternative to full feature ventilators, which will be in short supply and are too expensive for hospitals to stockpile. 

Rubinson, L., Branson, R.D., Pesik, N., Talmor, D. (2006). Positive pressure ventilation equipment for mass casualty respiratory failure. Biosecarity and Bioterror, 4, 1-11. 

Sleeplessness in ALS has numerous causes. Respiratory insufficiency, difficulty repositioning in bed, anxiety and depression can all contribute to poor sleep. Treatment of depression with sedating antidepressants such as mirtazapine, tricyclic antidepressants, or trazadone can help promote sleep. Zolpidem, a non benzodiazepine sleep aid, is effective and carries a low risk of respiratory depression. Other medications that can be helpful include anithistamines, chloral hydrate and selective use of benzodiazepines (Gordon and Mitsumoto, 2006). Non-invasive positive pressure ventilation can help relieve orthopnea in those with respiratory muscle weakness, and special equipment, such as a hospital bed, can reduce nighttime discomfort. 

Keller C, Sparr HJ, Brimacombe JR. Positive pressure ventilation with the laryngeal mask airway in non-paralysed patients comparison of sevoflurane and propofol maintenance techniques. Br J Anaesth 1998 80(3) 332-6. 

When nasal sufentanil was used to induce anesthesia in children, ventilatory compliance was mildly or markedly reduced and one child required suxamethonium, oxygen, and positive pressure ventilation (SEDA-16, 86). 

Hall SV, Johnson EE, Hedley-Whyte J. Renal hemodynamics and function with continuous positive-pressure ventilation in dogs. Anesthesiology 1974 41 (5) 452-61. 

Harvard rodent positive pressure ventilator (Harvard Apparatus Co.). 

Intubate via a tracheotomy and ventilate with room air at a tidal volume of 18-22 mL and 46-50 strokes/min using a Harvard rodent positive pressure ventilator. Continuously monitor the ECG (Fig. 4). 

Positive pressure ventilation via a face mask, such as biphasic intermittent positive airway pressure violation or continuous positive airway pressure ventilation... 

Positive airway pressure ventilation some experts recommend using positive pressure ventilation during the early, asymptomatic phase following phosgene exposure to prevent pulmonary edema. While positive pressure ventilation may reduce fluid accumulation, stabilize the intra-alveolar surfactant film and suppress arteriovenous shunts, many asymptomatic patients will find the treatment unacceptable (34). In addition, resources for providing prophylactic positive pressure ventilation may not be available in a mass-casualty situation. 

Nebulized aerosol is introduced to the patient by compressed air, either from a constant source or from a device known as intermittent positive-pressure ventilator. Nebulized aerosols rely less on the patient s own breathing pattern. Under some circumstances the dose administered to the patient by nebulizer is inconsistent or unpredictable. In a hospital setting, the aerosol administration can be supervised by qualified individuals. Home administration is not always supervised, and there is, therefore, a potential for misuse. 

When exposure to 1,1,1-trichloroethane ceases, regardless of route of exposure, the compound is rapidly cleared from the body, predominantly by exhalation of unchanged 1.1.1-trichloroethane in expired air (see Section 2.3.). Very little metabolism of the compound takes place, and despite a preferential distribution of absorbed 1,1,1 -trichloroethane to fatty tissues, significant retention does not occur without continued exposure. Thus, continued ventilation by the lungs will eliminate the compound from the body. Suggested methods to assist in lung ventilation include orotracheal and nasotracheal intubation for airway control and positive pressure ventilation techniques (Bronstein and Currance 1988 Ellenhorn and Barceloux 1988). 

C31. Cross, K. W., Dawes, G. 8., Hyman, A., and Mott, J. C., Hyperbaric oxygen and intermittent positive-pressure ventilation in resuscitation. Lancet II, 560-562 (1964). 

Use of Positive Pressure Ventilation (PPV) Fans to Reduce the Hazards of Entering Chemically Contaminated Buildings Summary Report (October 1999). Chemical Weapons Improved Response Program, U.S. Army Soldier and Biological Chemical Command. 

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