Acute Asthma management



Background

Consider the following for all patients with severe asthma

  1. Nasal prongs and highest tolerable O2flow. This can be given in addition to the 6 litres O2/min driving the nebuliser.
  2. IV fluids (2 l for average adult) on basis that the patient is dehydrated.
  3. IV magnesium 2g over 5 - 10 minutes has been shown to be useful [Cochrane]
  4. Start systemic steroids early [Cochrane]
  5. The use of intravenous beta 2 antagonists is controversial [Cochrane]

BTS Asthma Assessment
Near Fatal Asthma

↑PaCO2 and/or requiring mechanical ventilation with raised inflation pressures

Life Threatening Asthma Any one of the following in a patient with severe asthma:
  • PEF <33% best/predicted
  • SpO2 <92%
  • PaO2 <8 kPa
  • normal PaCO2 (4.6-6.0 kPa)

  • silent chest
  • cyanosis
  • feeble resp effort
  • bradycardia
  • dysrhythmia
  • hypotension
  • exhaustion
  • confusion/coma
Acute severe asthma Any one of:
  • PEF 33-50% best or predicted
  • resp rate >25/min
  • heart rate >110/min
  • inability to complete sentences in one breath
Moderate asthma exacerbation
  • Increasing symptoms
  • PEF >50-75% best or predicted
  • No features of acute severe asthma
Brittle asthma
  • Type 1: wide PEF variability (>40% diurnal variation for >50% of the time over a period >150 days) despite intense therapy
  • Type 2: sudden severe attacks on a background of apparently
    well-controlled asthma

Joint BTS SIGN algorithm management of acute asthma in adults
BTS / SIGN Mx algorithm

Normal Peak Flow Rates in Men

Height (top row = metres, Second row =inches)

MALE

1.55

1.6

1.65

1.7

1.75

1.8

1.85

Age

61

63

65

67

69

71

73

25

515

534

552

570

589

607

625

30

502

520

539

557

576

594

612

35

489

508

526

544

563

582

600

40

476

495

513

531

550

568

586

45

463

482

501

519

537

556

574

50

450

469

487

505

524

543

561

55

438

456

475

493

511

530

548

60

424

443

462

480

498

517

535

Normal Peak Flow Rates in Women

Height (top row = metres. Second row =inches)

FEMALE

1.45

1.5

1.55

1.6

1.65

1.7

1.75

Age

57

59

61

63

65

67

69

25

365

383

400

416

433

449

466

30

357

374

390

407

423

440

456

35

348

365

381

398

414

431

447

40

339

356

372

389

405

422

438

45

330

347

363

380

397

413

429

50

321

338

354

371

388

404

420

55

312

329

345

362

379

395

411

60

303

320

336

353

370

386

402



Content by Dr Íomhar O' Sullivan 23/04/2004. Reviewed by Dr ÍOS 20/07/2005, 30/04/2007. Last review Dr. Kanti Dasari, Dr. ÍOS 28/09/17.