It appears you have not yet registered with our community. To register for free click here
Rebreather World
       

Go Back   Rebreather World RBW Members General Section Dive Medicine Dive Medicine

Reply
 
LinkBack Thread Tools Display Modes
Old 20th November 2008, 18:28   #1 (permalink)
RBW Member
 
craige's Avatar

 
Join Date: Nov 2007
Location: Devon, England
Posts: 22
craige is an unknown quantity at this point
Hypercapnia and High Blood Pressure

I have just been listening to Alex Deas interview about his rebreather Alex Deas Interview, OR Apocalypse mCCR, eurotek '08 on Vimeo during this he states (about 15mins in to his talk) about carbon dioxide retention leading to significantly raised blood pressure.

My understanding is that carbon dioxide retention (ie hypercapnia) causes a respiratory acidosis. As breathing is mainly controlled via the brain stem in the respiratory centre where the drive to breathe is principally led by levels of carbon dioxide acting on chemoreceptors (secondary systems are hydrogen ions and oxygen). Hypercapnia thus leads to acute shortness of breath, headache and confusion. At a chronic level it can also act to increase the risk of oxygen toxicity and nitrogen narcosis.

However, I know nothing of how it can raise blood pressure. Particularly in such a short time of during a dive. Is Mr Deas confusing himself with pulmonary hypertension - this can happen in people with such as Chronic Obstructive Airways Disease (COAD). However, I am not aware that this relates directly to Blood Pressure.

Anyone able to shed some light?
(Offline)
 
Digg this Post!Add Post to del.icio.us
Reply With Quote
Old 21st November 2008, 02:27   #2 (permalink)
Dave Tomblin

 
wedivebc's Avatar

 
Hollis Prism 2, Megalodon
CCR Instructor Trainer
Join Date: Feb 2005
Location: Vancouver Island BC Canada
Posts: 3,565
wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute
Re: Hypercapnia and High Blood Pressure

Quote: (Originally Posted by craige) View Original Post
I have just been listening to Alex Deas interview about his rebreather Alex Deas Interview, OR Apocalypse mCCR, eurotek '08 on Vimeo during this he states (about 15mins in to his talk) about carbon dioxide retention leading to significantly raised blood pressure.

My understanding is that carbon dioxide retention (ie hypercapnia) causes a respiratory acidosis. As breathing is mainly controlled via the brain stem in the respiratory centre where the drive to breathe is principally led by levels of carbon dioxide acting on chemoreceptors (secondary systems are hydrogen ions and oxygen). Hypercapnia thus leads to acute shortness of breath, headache and confusion. At a chronic level it can also act to increase the risk of oxygen toxicity and nitrogen narcosis.

However, I know nothing of how it can raise blood pressure. Particularly in such a short time of during a dive. Is Mr Deas confusing himself with pulmonary hypertension - this can happen in people with such as Chronic Obstructive Airways Disease (COAD). However, I am not aware that this relates directly to Blood Pressure.

Anyone able to shed some light?
Good question. I wish I knew the answer but I will be watching this thread.
__________________
Cheers,

Dave....

www.wedivebc.com
(Offline)
 
Digg this Post!Add Post to del.icio.us
Reply With Quote
Old 21st November 2008, 19:56   #3 (permalink)
Pedant
 
dteubner's Avatar

 
Join Date: Mar 2005
Location: Adelaide, Australia
Posts: 258
dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all dteubner is a name known to all
Re: Hypercapnia and High Blood Pressure

Why does it matter? Lots of things (exercise for example) dramatically increase blood pressure but so what?
(Offline)
 
Digg this Post!Add Post to del.icio.us
Reply With Quote
Old 22nd November 2008, 22:55   #4 (permalink)
New Member
 
solocavediver's Avatar

 
Join Date: Apr 2006
Location: Leeds UK
Posts: 136
solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light solocavediver is a glorious beacon of light
Re: Hypercapnia and High Blood Pressure

Hi,

I googled a bit. I found an article on
with title High output heart failure.
It says in its abstract: The symptoms and signs of heart failure can occur in the setting of an increased cardiac output and has been termed 'high output heart failure'. An elevated cardiac output with clinical heart failure is associated with several diseases including chronic anaemia, systemic arterio-venous fistulae, sepsis, hypercapnia and hyperthyroidism. The underlying primary physiological problem is of reduced systemic vascular resistance either due to arterio-venous shunting or peripheral vasodilatation. Both scenarios can lead to a fall in systemic arterial blood pressure and neurohormonal activation leading to overt clinical heart failure.

So it seems to be saying the BP falls rather than rises (because of vasodilation) but, what the heck, it kills you anyway. In a diving scenario I guess "high output heart failure" might well end up simply being labelled "heart attack"...... and we do get a lot of those.

Extract from hypercapnia: Definition from Answers.com :

Hypercapnia


Symptoms

Symptoms of early hypercapnia, where arterial carbon dioxide pressure, PaCO2, is elevated but not extremely so, include flushed skin, full Rebreather World - Rebreathers for Scuba Diving - the next step, extrasystoles, muscle twitches, hand flaps, reduced neural activity, and possibly a raised blood pressure. In severe hypercapnia (generally PaCO2 greater than 10 kPa or 75 mmHg), symptomatology progresses to disorientation,


No mention of the reason why though.










Googling elsewhere I found someone (Therapeutic Hypercapnic Acidosis: Pushing the Envelope -- Swenson 169 (1): 8 -- American Journal of Respiratory and Critical Care Medicine) experimenting on rabbits (had ideas for therapeutic use of hypercapnia): "Their control and sick hypercapnic rabbits had higher blood pressures, lesser lactic acidosis, and better oxygenation than did the normocapnic controls."

(Doesn't tell you what the mechanism is either).









Also isn't it generally accepted that anything which stresses you out is likely to raise your BP - and hypercapnia certainly does that, I speak from experience.


Hmm. Dunno. Your guess is better than mine!

Cheers,

Charles.

Last edited by solocavediver; 22nd November 2008 at 23:02..
(Offline)
 
Digg this Post!Add Post to del.icio.us
Reply With Quote
Old 25th November 2008, 21:33   #5 (permalink)
RBW Member
 
craige's Avatar

 
Join Date: Nov 2007
Location: Devon, England
Posts: 22
craige is an unknown quantity at this point
Re: Hypercapnia and High Blood Pressure

Thanks for the responses.
(Offline)
 
Digg this Post!Add Post to del.icio.us
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT. The time now is 06:23.


RebreatherWorld.Com 2005 - 2013
Rebreather World, RBW and the Rebreather World Logo are Trademarks
All rights reserved, no republishing of content without written permission.
By using this website you have agreed to our Terms & Conditions of Use

free counters

Search Engine Optimization by vBSEO 3.1.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791